Jonmurgie Posted April 26, 2006 Report Share Posted April 26, 2006 Having just had some coilovers and adjustable top mounts fitted to our Rev 2 Tubby we're now experiencing some skittish-ness on the front end still, making it 'feel' unstable at speed and my wife is worried about driving it too fast! Also, the steering wheel doesn't flick back to centre with any great speed when you left go after going through a corner.. it just feels a little wrong! So, I thought I'd post up the alignment settings we went with and are looking for any advise on tweaking the settings to make the car feel a little more stable: front - left / right Camber: -0deg 48' / -0deg 48' Castor: +3deg 57' / +3deg 52' Toe: +0deg 04' / +0deg 04' Spring Rate: 170lbs Damper Setting: 6 out of 12 rear - left / right Camber: -1deg 20' / -1deg 10' Toe: +0deg 05' / +0deg 05' Spring Rate: 230lbs Damper Setting: 6 out of 12 I was also wondering whether it could be caused by worn bushes... the front shocks were clearly the originals and shot to hell, just wondering if the bushes could be the same and worth replacing? I should also point out that this is my Wife's every day car and not something we track so the settings are more for road use and tyre life... Any advice welcome please Cheers Jon Quote Link to comment Share on other sites More sharing options...
Tony Posted April 26, 2006 Report Share Posted April 26, 2006 Having just had some coilovers and adjustable top mounts fitted to our Rev 2 Tubby we're now experiencing some skittish-ness on the front end still, making it 'feel' unstable at speed and my wife is worried about driving it too fast! Also, the steering wheel doesn't flick back to centre with any great speed when you left go after going through a corner.. it just feels a little wrong! So, I thought I'd post up the alignment settings we went with and are looking for any advise on tweaking the settings to make the car feel a little more stable: front - left / right Camber: -0deg 48' / -0deg 48' Castor: +3deg 57' / +3deg 52' Toe: +0deg 04' / +0deg 04' Spring Rate: 170lbs Damper Setting: 6 out of 12 rear - left / right Camber: -1deg 20' / -1deg 10' Toe: +0deg 05' / +0deg 05' Spring Rate: 230lbs Damper Setting: 6 out of 12 I was also wondering whether it could be caused by worn bushes... the front shocks were clearly the originals and shot to hell, just wondering if the bushes could be the same and worth replacing? I should also point out that this is my Wife's every day car and not something we track so the settings are more for road use and tyre life... Any advice welcome please Cheers Jon Looks good so far?..... can you display The KPI aka SJI The wheel size and off-set (front) please. Quote Link to comment Share on other sites More sharing options...
Jap Devil Posted April 26, 2006 Report Share Posted April 26, 2006 Wheel size make a huge difference to the handling of the MR2....I was running 17 x 7 ET 40 all round with 215/35 front and 235/35 rear and suffered bad tramlining Changed to 16 x 7 front 16 x 8 rear with 205/45 and 245/45 respectively, had the geo done.....and bob's your uncle! Quote Link to comment Share on other sites More sharing options...
Jonmurgie Posted April 26, 2006 Author Report Share Posted April 26, 2006 Thanks guys... KPI 20deg is: +13deg 51' - left +13deg 38' - right Wheels are standard Revision 2/3 15's with the correct size tyres (195/55 front and 225/50 rears) with the tyres being fitted early Feb. I know what your saying about the wheels/tyres on the MR2 though, this is the 3rd one we've had (all Turbo as well) and have had 17's on the other ones and it took some time to get those right, and they always tramlined anyhow! I'm personally not a great fan of the MR2 and believe them to feel a little skittish on the front anyhow due to the total lack of weight up there! I also find the ABS on them a pain when your braking over bumpy ground as the front gets light so the abs kicks in etc... that was on the previous cars, not had that on our current one?! Quote Link to comment Share on other sites More sharing options...
Tony Posted April 26, 2006 Report Share Posted April 26, 2006 Thanks guys... KPI 20deg is: +13deg 51' - left +13deg 38' - right Wheels are standard Revision 2/3 15's with the correct size tyres (195/55 front and 225/50 rears) with the tyres being fitted early Feb. I know what your saying about the wheels/tyres on the MR2 though, this is the 3rd one we've had (all Turbo as well) and have had 17's on the other ones and it took some time to get those right, and they always tramlined anyhow! I'm personally not a great fan of the MR2 and believe them to feel a little skittish on the front anyhow due to the total lack of weight up there! I also find the ABS on them a pain when your braking over bumpy ground as the front gets light so the abs kicks in etc... that was on the previous cars, not had that on our current one?! Still everything looks good.... but lazey.. there is a hidden rule for your type of car regarding the castor and kpi... this rule is the 16 degree club? Their needs to be a constructed configuration between the castor/kpi angles generating an overall figure of about 16 degrees for a RWD car of this type, in your situation it's 13 deg kpi + near to 4 deg castor at almost 0 toe. Due to the lack of weight acting on the kpi the inclination is 'declined' hence the 13.38 position. This means any small reaction to the steering would 'incline' the kpi and make the angle active, but this reaction is shallow in the most desperate of cases.... so we are left with castor and toe.... The Mechanical castor trail is very low at 4 degrees with a very 'typical' small turning radius. Adding inertia with a bigger wheel would add a pneumatic trail and centrifugal resistance, but still to low to be of any value. Now we have just toe. At 0.4mm+ partial equals .8'+ total front toe this is to low.... 20' positive total is a conservative position... 40' is even possible without violating the tyres..... So in summery we could have FRONT camber: conical/ compression at 48'- and the reaction would be at about 30' intruding the kpi with equal values of 30'. castor, mechanical at near to 4 degrees, reactive to the rear bump/compression at about 20'.... this is very low due to the suspension modifications..... bump on/off would be low in support. castor, pneumatic and scrub radii -10 to 20 mm taken at the 0 off-set. Front toe seems to be the only evolution here.... 20' positive 'partial' 40' total seems wise to me. Quote Link to comment Share on other sites More sharing options...
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