Gearshifting, What do YOU do

Wondering how you shift gears, do you 1) keep full throttle while shifting 2) release throttle while shifting 3) use a clutch device (and release throttle) 4) use automatic shifting I was wondering this, because keeping full throttle tends to upset the car, that's bad in the middle of a corner. (I know, you're not supposed to shift there). Besides, it's overrevving the engine, and it will definetly blow in the final version. But releasing throttle is so difficult (at least to me), and it costs time. Please give me your opinion Martijn Keizer

#2 TB..and here's why. Most of the motley crue that drives today has been spoonfed on our modern Gearbox racers. F1 cars shift on the fly in microseconds...CART CHAMP cars sequential gearbox also has shift on the fly capabilities...The N2 model did address the clutch for several reasons...mainly, cuz they probably didn't have a clue how to do it back then. And controllers are very limited in the clutch pedal area. TSW I have heard will be bringing that option out. Now...finally my reason...You will have to learn the most basic of racing techniques if you use a clutch...Heel-Toe footwork. Your heal on the brake, toes on the gas, and the left foot on the brake...Learn it now or be left behind by the big shots. So while lifting off the gas may seem foreign to you...after a day or two of concentrating on it...you'll be feeling odd driving the other sims where you keep the gas mashed. Good luck dave henrie

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> Wondering how you shift gears, do you > 1) keep full throttle while shifting > 2) release throttle while shifting > 3) use a clutch device (and release throttle) > 4) use automatic shifting > I was wondering this, because keeping full throttle tends to upset the car, > that's bad in the middle of a corner. (I know, you're not supposed to shift > there). Besides, it's overrevving the engine, and it will definetly blow in > the final version. But releasing throttle is so difficult (at least to me), > and it costs time. > Please give me your opinion > Martijn Keizer

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> Wondering how you shift gears, do you > 1) keep full throttle while shifting > 2) release throttle while shifting > 3) use a clutch device (and release throttle) > 4) use automatic shifting > I was wondering this, because keeping full throttle tends to upset the car, > that's bad in the middle of a corner. (I know, you're not supposed to shift > there). Besides, it's overrevving the engine, and it will definetly blow in > the final version. But releasing throttle is so difficult (at least to me), > and it costs time. > Please give me your opinion

As you make mention of, I normally go thru a corner in one gear. On a good lap I change from 3rd to 4th as I begin turning into T3. T4 is the ***e though. Changing from 2nd to 3rd seems necessary about 2/3 thru T4 but if you hang on tight you can do it. It's more a matter of wheel control than anything. Or maybe I should be trying going thru it in 3rd. Like I need to stop trying to get thru the last turn in 2nd instead of 1st. Seems compression lockup is a big part of this sim as it should be :)

History lesson, folks....... It was the normal practice to NOT take the foot off the accelerator when changing UP. In fact, most up changes were made without even using the clutch. A good driver could change gear without incurring the slightest "crunch" simply by sensing the engine revs to the last 10 rpm!!

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> Wondering how you shift gears, do you > 1) keep full throttle while shifting > 2) release throttle while shifting > 3) use a clutch device (and release throttle) > 4) use automatic shifting > I was wondering this, because keeping full throttle tends to upset the car, > that's bad in the middle of a corner. (I know, you're not supposed to shift > there). Besides, it's overrevving the engine, and it will definetly blow in > the final version. But releasing throttle is so difficult (at least to me), > and it costs time. > Please give me your opinion > Martijn Keizer

-- Bruce. (At home)

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>Date: 4/8/98 2:41 PM Pacific Daylight Time<BR> ><BR> >History lesson, folks.......<BR> ><BR> >It was the normal practice to NOT take the foot off the accelerator when<BR> >changing UP. In fact, most up changes were made without even using the<BR> >clutch. A good driver could change gear without incurring the slightest<BR> >"crunch" simply by sensing the engine revs to the last 10 rpm!!<BR> ><BR> ><BR> >> Wondering how you shift gears, do you<BR> >><BR> >> 1) keep full throttle while shifting<BR> >> 2) release throttle while shifting<BR> >> 3) use a clutch device (and release throttle)<BR> >> 4) use automatic shifting<BR> >><BR> >> I was wondering this, because keeping full throttle tends to upset the >car,<BR> >> that's bad in the middle of a corner. (I know, you're not supposed to >shift<BR> >> there). Besides, it's overrevving the engine, and it will definetly blow >in<BR> >> the final version. But releasing throttle is so difficult (at least to >me),<BR> >> and it costs time.<BR> >><BR> >> Please give me your opinion<BR> >><BR> >> Martijn Keizer<BR> ><BR> ><BR> ><BR> >--<BR> >Bruce.<BR> >(At home)<BR> ><BR> ><BR> ></HTML>

All you have to do is fire up your copy of the movie Grand Prix and listen to how they shift, to see that Bruce is correct. In this sim at least, if you let off in a corner to shift, you will spin, period. Keep the hammer down! This is the first sim that I have wanted to shift manually. I'm fairly new to sim racing, and up till now, it's been all I can do to set the cars up and stay on the track ( ICR2, GP2, F1RS & TOCA )! You almost have to manually shift this car just to keep the engine up on the cams, otherwise it's dog slow. This thing reminds me of my first car, an old MGA, but with a whole lot more horsepower! It swivels and shakes and has no brakes but you gotta love it! One beef though, I hope, in the final version, the tach on the dash will be turned so that redline for the respective engine reads straight up.Look at most of the cars from that era, and the vintage cars run today, all the important gauges would be oriented so that when all was well, the needles pointed straight up. That way, the driver just had to glance at the instrument to check for trouble. Back to The Glen! Don

> One beef though, I hope, in the final version, the tach on the dash will be > turned so that redline for the respective engine reads straight up.Look at most > of the cars from that era, and the vintage cars run today, all the important > gauges would be oriented so that when all was well, the needles pointed > straight up. That way, the driver just had to glance at the instrument to check > for trouble. Spot on with that observation, Don. However, the "red line" in the demo is, in fact, the tell-tale. I haven't actually noticed a "red" area on the tach itself. Incidentally......you had an MGA. I have a TC and can relate to this sim like no other!! :-) -- Bruce (Fyshwick) "I hate music, especially when it's played." (Jimmy Durante)

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> History lesson, folks....... > It was the normal practice to NOT take the foot off the accelerator > when > changing UP. In fact, most up changes were made without even using > the > clutch. A good driver could change gear without incurring the > slightest > "crunch" simply by sensing the engine revs to the last 10 rpm!!

Hmm........With unsyncronized 'boxes it is common practice to upshift with no *clutch*, however, you let off the throttle an instant to avoid over-revving the engine, and in case you miss your shift. I am quite sure Papy has programmed something into this sim, like if you keep your foot down, the engine won't last a full distance. In these days, you can either get a switch that will "kill" the coil for an instant as you press (or nip) the cluch while shifting, stopping the engine. In the hi-tec sequential and F1 boxes, an engine cutout is programmed in. On downshift, one can also drop the clutch, however, it tends to ruin your dog-rings, and lock up the rears, hence heel-and toe shifting. I have tried an Hewland FGB box in a sports-prototype, and you can shift pretty dung fast, but you need to get off the gas..... remember, if your redline is at 11500, you shift at, say 11200, and if you keep the throttle in (without rev-limiter), you'll see 12000 in an instant:::) Isn't the wild cams of the Lotus/Ford engine programmed nicely? first, nothing, then take off::))) Matt -- Matthew Birger Knutsen Cheek Racing Cars (http://home.sn.no/~kareknut) "Racing cars is like dancing with a chainsaw" -Cale Yarborough

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> I work for a car company and, last night, I got to take a Mini Cooper > home. > It's the first time I've ever driven one and it reminded me very much > of GPL, > and vice-versa. Very direct and mechanical-feeling, and you really > have to > choose the right gear. The brakes didn't seem very good either, > though maybe > it's just the particular sample I had. > If only I could have driven it over to the Glen for some laps... > Mark

Well, buy it!!!:) Minis are probably the best production cars to demonstrate how much fun driving was once upon a time! ! Matt (Mini owner & racer::) -- Matthew Birger Knutsen Cheek Racing Cars (http://home.sn.no/~kareknut) "Racing cars is like dancing with a chainsaw" -Cale Yarborough

I agree!!!

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> > I work for a car company and, last night, I got to take a Mini Cooper > > home. > > It's the first time I've ever driven one and it reminded me very much > > of GPL, > > and vice-versa. Very direct and mechanical-feeling, and you really > > have to > > choose the right gear. The brakes didn't seem very good either, > > though maybe > > it's just the particular sample I had. > > If only I could have driven it over to the Glen for some laps... > > Mark > Well, buy it!!!:) > Minis are probably the best production cars to demonstrate how much fun > driving was once upon a time! ! > Matt > (Mini owner & racer::) > -- > Matthew Birger Knutsen > Cheek Racing Cars (http://home.sn.no/~kareknut) > "Racing cars is like dancing with a chainsaw" > -Cale Yarborough

Correct me if I am wrong, in a skip barber car, you only hit the clutch downshifting, but you keep the car full throttle upshifting

On Wed, 08 Apr 1998 22:47:44 -0700, Dave Henrie

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> #2 TB..and here's why. > Most of the motley crue that drives today has been spoonfed on our modern >Gearbox racers. F1 cars shift on the fly in microseconds...CART CHAMP cars >sequential gearbox also has shift on the fly capabilities...The N2 model did >address the clutch for several reasons...mainly, cuz they probably didn't have >a clue how to do it back then. > And controllers are very limited in the clutch pedal area. TSW I have heard >will be bringing that option out. > Now...finally my reason...You will have to learn the most basic of racing >techniques if you use a clutch...Heel-Toe footwork. Your heal on the brake, >toes on the gas, and the left foot on the brake...Learn it now or be left >behind by the big shots. So while lifting off the gas may seem foreign to >you...after a day or two of concentrating on it...you'll be feeling odd driving >the other sims where you keep the gas mashed.

Heel and Toe TOES on the brake and HEEL on the throttle. (Unless you're driving a truck with the throttle in the middle) I defy anyone to brake with as much modulation and feel using their heel compared to their toes. -- Nathan Wong http://www.nectar.com.au/~alfacors - Super Touring - Alfa Romeo - - V8Supercars - CART -

I think its called Flat shifting. Used to flat shift an rs200 Escort years ago. > Correct me if I am wrong, in a skip barber car, you only hit the clutch > downshifting, but you keep the car full throttle upshifting -- In a feeble attempt to thwart spammers I have altered my email address. Remove the obvious bit before replying. "... and the Information Superhighway gave us all the chance to find out Homer the Great

On Wed, 08 Apr 1998 22:47:44 -0700, Dave Henrie > Now...finally my reason...You will have to learn the most basic of racing >techniques if you use a clutch...Heel-Toe footwork. Your heal on the brake, >toes on the gas, and the left foot on the brake...Learn it now or be left >behind by the big shots. I'd like to see anyone learn to drive like that! Ouch! "Heel and toe" is simply braking with the majority of your right foot, while the right hand side of your right foot "blips" the throttle before engagin gear on the downshift. The "heel" part is simply the pivot as your foot moves from accelerator across to brake. Someone at a driving school once told me that the name came from the good old days when the accelerator was in the centre and the brake on the right, but I don't know for sure about that. Cheers! John

Totally agree, Nathan. That's the way I, and my colleagues, have practised it for the past 30 years.

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> Heel and Toe > TOES on the brake and HEEL on the throttle. (Unless you're driving a > truck with the throttle in the middle) > I defy anyone to brake with as much modulation and feel using their > heel compared to their toes. > -- > Nathan Wong http://www.nectar.com.au/~alfacors > - Super Touring - Alfa Romeo - > - V8Supercars - CART -

-- Bruce. (At home)

Oops.... Clicked on Post instead of File on the last message. "Dog" rings. ____________________________ |____________________________| |___| ___ |___| ___ |___| _______|___|_______|___|________ |_____________________________| This is a side view of two racing transmission gear engagement "dog" rings with straight cut teeth. One rotates with the engine and the other with the differential (rear wheels). When a gear is selected they are brought together and the teeth engaged. It may be possible to disengage them without lifting off the throttle and when the teeth start to wear they may slip out of engagement (Trans. "pop" out of gear). ____________________________ |____________________________| /___\ ____ /___\ ____ /___\ _______\___/__ ____\___/_______ |____________________________| These are "undercut" dog rings. The teeth are cut at an angle to give more positive engagement and prevent slipping out of gear. Nearly all new transmissions have this type. The teeth can not be disengaged unless power is reduced by either a slight lift on the throttle or an ignition cut out switch on the gear shifter. Both of these types of dog ring require "Blipping" or raising the throttle a slight bit on downshifts to match rear wheel dog ring speed to engine dog ring speed for a smooth engagement. Different types of pedal setups and foot sizes may use different methods of "heel and toe" to blip the throttle. Dog ring are usually the first thing to wear out in a transmission because of not matching the rpm's to the rear wheels. You probably don't have to worry about this in a racing sim unless it has a transmission damage setting. D Sport Racer #74

Correctomundo! I let literalness get in the way...the concept was right the explanation was way off. Thanks for the correction dave

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> On Wed, 08 Apr 1998 22:47:44 -0700, Dave Henrie > > Now...finally my reason...You will have to learn the most basic of racing > >techniques if you use a clutch...Heel-Toe footwork. Your heal on the brake, > >toes on the gas, and the left foot on the brake...Learn it now or be left > >behind by the big shots. > I'd like to see anyone learn to drive like that! Ouch! > "Heel and toe" is simply braking with the majority of your right foot, > while the right hand side of your right foot "blips" the throttle > before engagin gear on the downshift. The "heel" part is simply the > pivot as your foot moves from accelerator across to brake. > Someone at a driving school once told me that the name came from the > good old days when the accelerator was in the centre and the brake on > the right, but I don't know for sure about that. > Cheers! > John

> Correct me if I am wrong, in a skip barber car, you only hit the clutch > downshifting, but you keep the car full throttle upshifting You can, but it's needlessly *** the transmission and half-shafts/CVs (hard full-cycle stress reversals). Breathing out of the throttle for the instant of the change and then putting it back to the stop is no slower, makes it easier to get out of the old gear (by unloading the dogs), and makes the drivetrain last longer. I think the "official" line while in the school is to use the clutch, but from off-the-record discussions with instructors, they almost universally approved of clutch-less upshifts for everyone who wanted to and understood vaguely what to do. (You also can do clutchless downshifts, which is worth practicing for the day you lose clutch hydraulics, but expect to spend plenty of your early downshifts stuck in neutral hunting for a gear, and making lots of ugly sounding noises.) ---Jim

Sorry this is a little late... been away from my copy of Pine for a few weeks! > History lesson, folks....... > It was the normal practice to NOT take the foot off the accelerator when > changing UP. In fact, most up changes were made without even using the > clutch. A good driver could change gear without incurring the slightest > "crunch" simply by sensing the engine revs to the last 10 rpm!! Erm... you can't keep it floored *and* not use the clutch. One or the other. Keeping it floored whilst smacking the clutch is called 'powershifting', and was used extensively in Touring Cars until recent years. It works best with a rev limiter. Clutchless shifting requires a brief cut in power. This is now achieved in all Touring Cars and many other classes by cutting the ignition for a split second (F1 engine management does a similar trick). If you're driving an endurance race you should be both lifting the throttle and using the clutch - you'll break something otherwise. Jonny --------------------------------------------------------------------- | Jonathan Hodgson | TTech Predator | | than win by two laps | LSU Archery Club and Orchestra | ---------------------------------------------------------------------

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> Sorry this is a little late... been away from my copy of Pine for a few > weeks! > > History lesson, folks....... > > It was the normal practice to NOT take the foot off the accelerator when > > changing UP.

You may not have to take your foot off the accelerator, but you'd better take the accelerator off the high-limit pedal stop... :-) You "can", and you'll even get the gearbox to engage sometimes, but you'll be putting maximum fully-reversed stresses on the drivetrain, and you can expect to see the insides of the gearbox on a VERY regular basis. In order to match revs (and have the gearbox/drivetrain have a chance), the most elementary analysis reveals that you have to lift to match revs (barring drive-by-wire computer controlled shenanigans). It's still *** the clutch and drivetrain when there is no computer-controlled integration (other than a rev limiter) intervening on behalf of the driver. There's some differing schools of thought on that topic. Matching revs on shifts and not declutching may in fact create the highest probability of finishing an endurance race, particularly if the clutch is the weak link. School #1: Use the clutch to get underway from rest and from the pits and leave it alone otherwise; you can design a fairly light-duty (low reciprocating mass) clutch and pressure plate that can start the car once an hour. In modern endurance cars with purpose built gearboxes, I would predict this is a lower-risk approach (given talented drivers) than banging the clutch each time. School #2: Others (in the business) will claim that declutching every time is a win. (Probably depends on the drivers, and you can design the cars around the drivers' talents and educate the drivers around the limits of the machine to a certain extent.) ---Jim

(good stuff snip) IMO, School#3 Use the clutch when downshifting, to make sure the back end does'nt come around and bite yer feet off:-) "Heel & Toe". At the closest track to our workshop, there is a *tight* 2nd/1st gear bend leading onto the pit straight. Approaching this bend, you are flashing over a crest in a little S-turn, 4th gear, then you try to find a somewhat straight line towards the Apex to brake/downshift. One of my fav time wasters (when I am a spectator, that is!) is to sit and watch people handle this challenge. The F3 guys are the most fun to watch, too busy steering to use the clutch or listen to the revs-,approaching the bend at well over 110MPH,*** on the brakes, and start to downshift; Whiiine--crash !! the dog rings shout Wheeee-pop-pop the engine goes Screech-screech the locked rear wheels shout And sooner or later (in about 3 laps), they arrive at the turn looking *away* from the Apex! But they learn...., crawling out of their tire-stained Dallaras:))) Pardon the wacky sound effects!:)) Matt -- Matthew Knutsen Cheek Racing Cars [link lost in import: /~kareknut/]

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> IMO, School#3 > Use the clutch when downshifting, to make sure the back end does'nt come > around and bite yer feet off:-) "Heel & Toe". > At the closest track to our workshop, there is a *tight* 2nd/1st gear > bend leading onto the pit straight. Approaching this bend, you are > flashing over a crest in a little S-turn, 4th gear, then you try to find > a somewhat straight line towards the Apex to brake/downshift. > One of my fav time wasters (when I am a spectator, that is!) is to sit > and watch people handle this challenge. The F3 guys are the most fun to > watch, too busy steering to use the clutch or listen to the > revs-,approaching the bend at well over 110MPH,*** on the brakes, > and start to downshift; > Whiiine--crash !! the dog rings shout > Wheeee-pop-pop the engine goes > Screech-screech the locked rear wheels shout > And sooner or later (in about 3 laps), they arrive at the turn looking > *away* from the Apex! > But they learn...., crawling out of their tire-stained Dallaras:))) > Pardon the wacky sound effects!:)) > Matt > -- > Matthew Knutsen > Cheek Racing Cars > [link lost in import: /~kareknut/]

Hi Matt That would be Rudskogen Raceway you`re talking about right :-) If so, braking for that left IS difficult to get right ! I`ve driven enough laps in my roadcar to know THAT (I clutch both on the upchange AND the downchange btw :-), especially the first laps I did with my new engine, I suddenly had a "few" more mph coming over the crest :-), locking the right front because it is lightly loaded AND stone cold since it doesn`t do much work and then ask that same wheel to do the turn in for you, yeah right I`ve never gotten it quite right, although I don`t think I`ve ever lost it totally either, but I HAVE been in the sandtrap on the exit trying to get a jump on those darn Cosworths, it ain`t easy for them to get it right when you have that Turbo-lag :-), if I get it reasonably right I can usually tag onto their tail coming out of the carousell and onto the main straight, then it becomes a question of who is the most stupid when we brake for that righthander at the end, I HAVE been pretty far into the sandtrap there :-) Btw, do you do setup work on roadcars Matt ? I have some ideas for a 4 link rear suspension for my trusty old Opel Manta, but I`m not sure about lenghts and angles and stuff for the linkages. Beers and cheers (uncle) Goy UncleGoy on TEN

> I have some ideas for a 4 link rear suspension for my trusty old Opel > Manta, but I`m not sure about lenghts and angles and stuff for the > linkages. Now there's a plan! Could be pretty good... what've you done to the Manta so far? I'm getting into things like suspension geometry (I've run model race cars for the past nine years) so I'll see if I can manage a few pointers (though it's complicated - best do some reading up. Does Milliken and Milliken cover it?) Lower wishbones want to be as long as possible, for best control. They generally should run about horizontal as a first approximation. Top wishbones should be shorter (~1/2 - 3/4 as long) and should be angled downwards and inwards. They'll converge (if you imagine them extended) with the lower arms at a point somewhere the other side of the vehicle. The length out to that point is the swing axle length. A longer SAL is better in squat (acceleration) whilst a shorter one keeps the outside wheel more upright in roll (cornering) - like everything, it's a compromise! Bring a line from this point (the instantaneous roll centre) back to the centre of the tyre contact patch. Where this new line crosses the vehicle centreline is your rear roll centre. An equivalent construction can be made for the front, and in general the rear RC should be higher than the front - perhaps the front one at ground height and the rear a couple of inches higher? Don't know what Manta front suspension is... If you want maximum learning value, design brackets with several alternative mounting holes and move things around to feel what it does! I'm crossposting this to rec.autos.sport.tech - it might be an idea to move the discussion there, if you're serious about getting some answers! Jonny --------------------------------------------------------------------- | Jonathan Hodgson | TTech Predator | | than win by two laps | LSU Archery Club and Orchestra | ---------------------------------------------------------------------

For Racing Purposes only! The top links should be close to the same length as the lowers and to stay parallel to each other. The shorter the top links are cf the lowers the closer to the center of the axle (assuming the manta stillhas its live axle). The reason is mid corner or bump steer, causing snap oversteer. For reference see two simliar road cars the pre 86 Mazda Rx7 and the pre 86 Corrolla AE86 16V GT rwd. Both have 4 link rears (ok 5 with watts on RX and pan*** AE86). Both setups are similar with top links under 50% of lowers. The AE86 ties the top links to eitherside of the diff housing and has excellent handling for road. The RX7 ties them to the outer ends of the axle, causing serious wheelbase changes on the compressed side of the car after about 4 degs of roll! Mind you the lively feel adds to the cars 'character'! The panhard rod solution is simpler than the Watts and nearly as effective, though theoretically watts is better. The RX7 however has a questionable unequal length implementation. Another car to look at is the simpler design of the UK Rover SD1 1976-86. This has long lower arms, and mount on an extended diff nose. A li ecan be drawn through the chassis mounts of the arms and the chassis mount of the diff mount. The diff mount is designed to give the axle a slight nose down attitude. A watts linkage (equal length) provides the lateral control. I race an RX with the standard tail...the clerks of course are getting peed off with my spinning....the car of course...it couldn't be the driver! PS. the back end of the Manta isn't bad anyroad. Best options for modification are to lok at the Tarmac rally spec Manta 400 IanC

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> > I have some ideas for a 4 link rear suspension for my trusty old Opel > > Manta, but I`m not sure about lenghts and angles and stuff for the > > linkages. > Now there's a plan! Could be pretty good... what've you done to the Manta > so far? > I'm getting into things like suspension geometry (I've run model race cars > for the past nine years) so I'll see if I can manage a few pointers > (though it's complicated - best do some reading up. Does Milliken and > Milliken cover it?) > Lower wishbones want to be as long as possible, for best control. They > generally should run about horizontal as a first approximation. > Top wishbones should be shorter (~1/2 - 3/4 as long) and should be angled > downwards and inwards. They'll converge (if you imagine them extended) > with the lower arms at a point somewhere the other side of the vehicle. > The length out to that point is the swing axle length. A longer SAL > is better in squat (acceleration) whilst a shorter one keeps the outside > wheel more upright in roll (cornering) - like everything, it's a > compromise! > Bring a line from this point (the instantaneous roll centre) back to the > centre of the tyre contact patch. Where this new line crosses the vehicle > centreline is your rear roll centre. > An equivalent construction can be made for the front, and in general the > rear RC should be higher than the front - perhaps the front one at ground > height and the rear a couple of inches higher? Don't know what Manta > front suspension is... > If you want maximum learning value, design brackets with several > alternative mounting holes and move things around to feel what it does! > I'm crossposting this to rec.autos.sport.tech - it might be an idea to > move the discussion there, if you're serious about getting some answers! > Jonny > --------------------------------------------------------------------- > | Jonathan Hodgson | TTech Predator | > | than win by two laps | LSU Archery Club and Orchestra | > ---------------------------------------------------------------------

-- +------------------------------------------------------------------+ | Ian Cowley Network Design Consultant | | WWW [link lost in import: /;|] | | +------------------------------------------------------------------+

Hi Jonny Thanx for the input and the tip about the other newsgroup as well, but I have the feeling that you are talking about a "double wishbone" setup here, but I was talking about adding two more linkages to my "live axle" setup. Although I`d love the idea of your suggestion, that would really be out of my league Beers and cheers (uncle) Goy UncleGoy on TEN

> For Racing Purposes only! > The top links should be close to the same length as the lowers and to > stay parallel to each other. > The shorter the top links are cf the lowers the closer to the center of > the axle (assuming the manta stillhas its live axle). Stupid "torque-tube" suspension yes :-) I think I`ll go for the Corolla setup then :-) From what I`ve read, as long as the suspension doesn`t give TOO much wheel travel, there isn`t THAT much to be gained from converting to watts linkage anyway I`ll check at the breakers, but there not many of those cars here in Norway, not Corolla AE86 GT`s or RX7`s either for that matter Of course not :-) Manta 400 HAS 4 link suspension, rear axle from Opel Commodore with modified (?) linkages, a friend of mine once owned an Ascona 400 and I rember with joy how that one used to squat down at the rear when applying power through a corner, my car however raises the rear end and starts spinning the inner wheel in low-mid speed corners, luckily the LSD is only 40% or I`d have some really scary moments :-) The 400`s also uses modified front suspension angles (there are different wishbones for the 400`s, I`ve checked) wich means that even if I could get a good look at the rear suspension, there is the possibility that I could get it all wrong anyway and end up with something that handles badly, wich my car doesn`t do at the moment, it just doesn`t get the power down A friend of mine has a rear axle from an Opel Rekord/Vauxhall Carlton lying around, which is a 4 link setup, and it`s this axle that will be the base of my design, unless someone comes up with something better. There is the question of cost here too, I can`t go to a race shop and say; "Here are the keys to my car, sort out the suspension and send me the bill" :-), besides, a lot of the enjoyment comes from doing it yourself with the help from others of course, I know my limitations (roughly :-) Beers and cheers (uncle) Goy UncleGoy on TEN

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> > For Racing Purposes only! > > The top links should be close to the same length as the lowers and to > > stay parallel to each other. > > The shorter the top links are cf the lowers the closer to the center of > > the axle (assuming the manta stillhas its live axle). > Stupid "torque-tube" suspension yes :-) > > The reason is mid corner or bump steer, causing snap oversteer. > > For reference see two simliar road cars the pre 86 Mazda Rx7 and the pre > > 86 Corrolla AE86 16V GT rwd. > > Both have 4 link rears (ok 5 with watts on RX and pan*** AE86). > > Both setups are similar with top links under 50% of lowers. > > The AE86 ties the top links to eitherside of the diff housing and has > > excellent handling for road. > > The RX7 ties them to the outer ends of the axle, causing serious > > wheelbase changes on the compressed side of the car after about 4 degs > > of roll! > > Mind you the lively feel adds to the cars 'character'! > I think I`ll go for the Corolla setup then :-) > > The panhard rod solution is simpler than the Watts and nearly as > > effective, though theoretically watts is better. The RX7 however has a > > questionable unequal length implementation. > From what I`ve read, as long as the suspension doesn`t give TOO much > wheel travel, there isn`t THAT much to be gained from converting to > watts linkage anyway > > Another car to look at is the simpler design of the UK Rover SD1 > > 1976-86. > > This has long lower arms, and mount on an extended diff nose. A li ecan > > be drawn through the chassis mounts of the arms and the chassis mount of > > the diff mount. The diff mount is designed to give the axle a slight > > nose down attitude. A watts linkage (equal length) provides the lateral > > control. > I`ll check at the breakers, but there not many of those cars here in > Norway, not Corolla AE86 GT`s or RX7`s either for that matter > > I race an RX with the standard tail...the clerks of course are getting > > peed off with my spinning....the car of course...it couldn't be the > > driver! > Of course not :-) > > PS. the back end of the Manta isn't bad anyroad. Best options for > > modification are to lok at the Tarmac rally spec Manta 400 > Manta 400 HAS 4 link suspension, rear axle from Opel Commodore with > modified (?) linkages, a friend of mine once owned an Ascona 400 and I > rember with joy how that one used to squat down at the rear when > applying power through a corner, my car however raises the rear end and > starts spinning the inner wheel in low-mid speed corners, luckily the > LSD is only 40% or I`d have some really scary moments :-) > The 400`s also uses modified front suspension angles (there are > different wishbones for the 400`s, I`ve checked) wich means that even if > I could get a good look at the rear suspension, there is the possibility > that I could get it all wrong anyway and end up with something that > handles badly, wich my car doesn`t do at the moment, it just doesn`t get > the power down > A friend of mine has a rear axle from an Opel Rekord/Vauxhall Carlton > lying around, which is a 4 link setup, and it`s this axle that will be > the base of my design, unless someone comes up with something better. > There is the question of cost here too, I can`t go to a race shop and > say; "Here are the keys to my car, sort out the suspension and send me > the bill" :-), besides, a lot of the enjoyment comes from doing it > yourself with the help from others of course, I know my limitations > (roughly :-) > Beers and cheers > (uncle) Goy > UncleGoy on TEN

OK Lets work from your info: Mid corner lifts inside rear wheel and you feel as if it is raising the rear - not common to my knowledge on live axle however hear goes. With wheels on the ground, and with the car preferably stationary (vbg) measure all the suspension components and then draw them up on paper On a rear wheel drive car we normally want the front inner to lift before the rear. If you don't get squat under straight line power, then the geometry is giving you anti-squat. This normally means that the lower arm is higher at the front than rear. Measure how much. Put 50Kg of weight in the boot and try again! Repeat until squat occurs. this should happen within 150kg. Infact I'm sure an Opel Manta Berlinetta I drove always squatted. Might be worth looking for siezed components such as dampers. Once squat occurs test cornering, given the additional weight, and add weight to the front passenger foot well to lower front of car. Alternatively call PMC in UK and get a standard suspension kit. Changing the rear axle is a bit radical for DIY. If the dampers aren't damaged you basically need to lower the car. If ride height is important, lower the car and put larger wheels/tyres on. You guys need two sets of wheels any way so the summer wheels/tyres could be the standard 195/60/14 and the winters 195/70/14. IanCT -- +------------------------------------------------------------------+ | Ian Cowley Network Design Consultant | | WWW [link lost in import: /;|] | | +------------------------------------------------------------------+

>I'm crossposting this to rec.autos.sport.tech - it might be an idea to move the discussion there, if you're serious about getting some answers! > Jonny That's a great idea! How about NOT posting it to rec.autos.simulators, where the mysteries of Opel suspension mods are quite off topic? Just a helpful note: Milliken and Milliken is fine on theoretical stuff, but I think you'll find more practical information in Herb Adams' book on chassis and suspension design, as well as Forbes Aird's "Race Car Chassis Design and Construction", Allan Staniforth's "Competition Car Suspension", and even the venerable Carroll Smith's "Tune to Win". But please...not in rec.autos.simulators -- unless you're planning a chassis-design add-on to one (or more) of the current or future racing.sims. If that's so, please keep me informed! Bart Brown

> OK > Lets work from your info: > Mid corner lifts inside rear wheel and you feel as if it is raising the > rear - not common to my knowledge on live axle however hear goes. I didn`t give you much to work from did I :-) The Manta has what is called a "torque-tube" which goes from the diff housing and forward some distance and is then mounted to the body, this tube is what prevents "wind-up" in the axle when I apply power. This is a cheap way of locating the axle and works very well whith the original engines, once we get more power however, the picture changes. I now have enough power in the car to actually generate lift through that "torque-tube", not a big problem in a straight line on dry surface, but on loose surface and in corners, forget it I`ve never messured the length of it, but it is of course roughly the same lenght as the suspension linkages themselves Will do You`ve seen Ari Vaataanen drive Escorts on tarmac, haven`t you :-) Haven`t thought of that, but from my answer below, I`d say it wasn`t The car is lowered with progressive springs up front (40mm) and modified originals at the rear, yellow Konis all around and stiffer suspension ***s will be fitted soon. I also have a stiffer anti-roll bar at the front. The car is slightly lower at the rear than at the front for better weight distribution/transfer Don`t really want to lower it any further because then I`d limit the suspension travel too much, the rear bottoms out every now and then as it is Na, enjoy these things alot, ported the cylinder head on one of my previous engines myself with good results, although with afterthought I`d never do it again, at least not without the proper tools, too many hours wasted when you can get it done fairly cheaply even here in Norway See above I run 195/50/15, good compromise between grip, durablity (price) and comfort Basically my suspension is in good working order, or will be as soon as I get those ***s changed, there is nothing seized or rusted. The only other thing I can think of is the weight ditribution, the car weighs 1100 kg, about 550/450 front/aft, but unless I add a lot of weight at the rear there isn`t a whole lot I can do about that without going to extreme meassures, and this is a road car after all Thx again for taking the time Beers and cheers (uncle) Goy UncleGoy on TEN

> >I'm crossposting this to rec.autos.sport.tech - it might be an idea to move the discussion there, if you're serious about getting some answers! > > Jonny > That's a great idea! How about NOT posting it to rec.autos.simulators, > where the mysteries of Opel suspension mods are quite off topic? What do you mean off topic ? It`s recreational, at least for me. It`s autos And I try to simulate in my mind how to do this whithout getting totally broke Point taken I normally don`t crosspost either, but I didn`t know if Ian (the second responder) posted from this group or the other one, so I decided to keep it going in both groups for my own convenience, especially since there are many knowledegeable people in here as well. Anyone know if there is a way to tell which group ppl post from in a crossposted thread ? Beers and cheers (uncle) Goy UncleGoy on TEN