Gengis Posted March 17, 2019 Report Share Posted March 17, 2019 Hi I’m going to have the suspension set up soon and want to know ideal setting. The car is a Mk 2 Vitesse, with Gaz dampers all round, adjustable coil overs on the front, and adjustable top arms. Wheels are 6 inch mini lites with 185/60 tyres. It’s modified quite a bit so a fast road set up would be good. I understand you should put a weight on both seats What should that be? Car also has a limited slip diff if that makes a difference. Thanks Link to comment Share on other sites More sharing options...
SpitFire6 Posted March 17, 2019 Report Share Posted March 17, 2019 Hi, Sorry, I can't help with the settings you are looking for. I will also be interested in the settings that will soon be offered to you. Some additional info may be required; Original steel wheels or aftermarket? If aftermarket what ET? I used 185/60/13 tyres many moons ago and found the 10mm drop in ride height a pain over speed bumps. The 4% increase in speed reading made the car faster on the speedo though. Now I am 10% slower with my chosen combo. Good luck, Iain. Link to comment Share on other sites More sharing options...
Clive Posted March 17, 2019 Report Share Posted March 17, 2019 Not sure what is "best" but I can give you my figures. On a Spitfire but with (CV) rotoflex rear, and lowered front and rear...(car can be described as "fast road" but used for trackdays and autosolos as well as long distance touring etc Very stable at high speed on the autobahns, nimble on tests etc but still no Caterham) Front camber set to 1.5 degrees negative. Front and rear toe are zero Front and rear shocks (Koni!) set to approx 1/3rd front, and nearly the softest setting at the rear. Front sprints are 480lb, which is quite stiff but comfortable enough for european touring with the wife. The rear spring is std GT6 rotoflex, effectively using a 1" lowering block, but was used when fitted and really needs to be a bit stiffer. The steering rack has been raised by 5mm to reduce bumpsteer. Rear rotoflex inner wishbone mount holes are lower and 5mm further out than std. Car handles pretty well, just needs a stiffer rear spring as it is getting a bit too much movement (compression of the outer wheel) when doing fast/tight corners. However, car is needed nit to go too still. Likewise watch the front ARB. Do not be tempted to use the thicker one as that will increase understeer, especially with a 6 cylinder engine. The LSD will also increase the tendency to understeer (I have a viscous LSD which is quite forgiving, a plated or quaife diff will be less so) Sorry I can't give definitive answers. But do some reading on how to measure bump steer. There is also an article about reducing camber change at the rear (suspension sussed or something like that) Likewise JohnD is on here and will hopefully contribute, he races a Vitesse... Link to comment Share on other sites More sharing options...
SpitFire6 Posted March 17, 2019 Report Share Posted March 17, 2019 Hi Clive, What tyre size you have? Cheers, Iain. Link to comment Share on other sites More sharing options...
Clive Posted March 17, 2019 Report Share Posted March 17, 2019 I use 185/60 13 for autosolo and some summer trackdays. General use/touring and winter trackdays I am using the excellent 185/60 14 crossclimates. Link to comment Share on other sites More sharing options...
Gengis Posted March 17, 2019 Author Report Share Posted March 17, 2019 I should also say it is lowered 3/4 inch at the back and has adjustable rear wishbone mounts with c/v joints. Thanks Link to comment Share on other sites More sharing options...
Pete Lewis Posted March 18, 2019 Report Share Posted March 18, 2019 The triumph manuals are clear the load on EACH seat is 150 lbs to get the static ride settings . there are unladen specs in the gt6 manual which saves getting bags of coal of rent a crowd in Setting it up unladen with laden figures will give poor steering and bump steer at the back if the rear toe is incorrect The static load puts the suspn. In a average running position as the toe changes with suspension travel. Pete Link to comment Share on other sites More sharing options...
Clive Posted March 18, 2019 Report Share Posted March 18, 2019 This may help with bumpsteer setup: http://sideways-technologies.co.uk/forums/index.php?/topic/6158-bump-steer/ Link to comment Share on other sites More sharing options...
Nick Jones Posted March 18, 2019 Report Share Posted March 18, 2019 6 hours ago, Pete Lewis said: The triumph manuals are clear the load on EACH seat is 150 lbs to get the static ride settings And it's hard to think of anything more pointless than quoting laden figures as it is NEVER going to happen. What a stupid way to give the specs...…. Unladen is the only one that stands a chance of being adhered to. Nick Link to comment Share on other sites More sharing options...
Pete Lewis Posted March 18, 2019 Report Share Posted March 18, 2019 it is common practise in car manufacture to specifiy geometry setting at a known /desined suspension position , many marques have this whether its pulled down on blocks or loaded with weights , no car drives or behaves in its kerb weight situation once you have the static setting you can un load and re measure to see what you now have as unladen . its all down to the varying different working lengths of wish bones track rods and uncle tom cobbley an all. all can move through varying arc's and this changes their operational lengths . as the suspn. moves up and down due to the influence of road and load many tyre bays don't consider it as they really want you to wear them out ,buy some more . Pete Link to comment Share on other sites More sharing options...
Clive Posted March 18, 2019 Report Share Posted March 18, 2019 But surely it is possible to work back? ie the factory does its research, works out what s best, then can measure the car unladen? Can't be too hard... Maybe I ought to compare my car with 2 people in it against empty, see what happens... (I guess the GT6 specs mentioned above do that?) Link to comment Share on other sites More sharing options...
JohnD Posted March 18, 2019 Report Share Posted March 18, 2019 Not, when as the OP has said, he has diffremt wheels, tyres and springs from anythiung the factory ever saw. JOhn Link to comment Share on other sites More sharing options...
Clive Posted March 18, 2019 Report Share Posted March 18, 2019 Sorry John, I was referring to the WSM giving suspension figures in a laden state. But I think the caster/toe factory figures work well whatever the modifications. Front camber is odd being positive in the WSM (shopping trolley steering??) and rear camber is almost whatever you end up with, unless you commission a custom spring and/or lower wishbones. Bump steer is the one that catches so many people out and can make a car terrible to drive. I wonder if some (many?) people have tried lowered springs, not altered anything else and find the car terrible to drive, and blame the springs? Link to comment Share on other sites More sharing options...
Pete Lewis Posted March 18, 2019 Report Share Posted March 18, 2019 i did say you can work back we did in the factory as the vans needs a ton of weight blocks to sit on spacers to get the height , once bitten . unload and see what the result was to get it set on track in a suspended state needed 3/8 toe in on the tyre to get 1/16 laden they all said thats rubbish but it worked and solved early life tyre wear., and on checking toe on the rim or on the tyre , 3mm on rim is doubled on the tyre periphery where as parallel makes no difference triumph do not specifiy the diameter the toe is measured at !!! back to a simple like gunsons side slip gauge ( trakrite) tells you exactly whats going on between tread and road surface and at £45 from amazon its a winner , 1 Link to comment Share on other sites More sharing options...
SpitFire6 Posted March 18, 2019 Report Share Posted March 18, 2019 Hi, The Trakrite makes sense to me. So I bought one. Bump-steer; can this not be eliminated by having the bottom wishbones parallel to the ground by using adjustable spring height dampers? Cheers, Iain. Link to comment Share on other sites More sharing options...
Pete Lewis Posted March 18, 2019 Report Share Posted March 18, 2019 Im sure that helps but what is hard to define is where it all sits as the car rides the road , very different to parked on the level probably why some have very long wishbones pivoting near the centre of the floor didnt BMW copy the triumph 2000 rear end ,, trailing arms but quite long ones pete Link to comment Share on other sites More sharing options...
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