Rake i.e. relative front and rear roll height
Discussion
Just had some new front shocks on my Tam and the handling on the drive home suggested the front is too low in relation to the rear. Measured sill to floor and got 125mm at the front and 135 mm at the rear (slight variance nearside/offside at rear of 3 mm with rear nearside measuring 138mm from sill to floor). As the rear sping/dampers are orginal this may be due to 15 years of extra weight from driver on the offside.
First off, does anyone know the desired rake and secondly what sort of tolerance is acceptable left / right across the axle?
First off, does anyone know the desired rake and secondly what sort of tolerance is acceptable left / right across the axle?
Hi measured to the sills my ride height is 145mm front and 155mm rear. How flat is your floor? my garage definitely is not within 3mm of flat.
I had new shocks and springs fitted in the winter and the ride height was raised 35mm at the front, to this level, this was a significant improvement instead of being twitchy it now tracks true and stable. (Dan Taylor is good). Corner weighting and geometry needs setting-up to match the shocks and any ride height change and the balance of damping front to rear adjusted.
Just replacing one ends shocks will take some time to get the adjustments right, which shocks do you have front and rear now?
I had new shocks and springs fitted in the winter and the ride height was raised 35mm at the front, to this level, this was a significant improvement instead of being twitchy it now tracks true and stable. (Dan Taylor is good). Corner weighting and geometry needs setting-up to match the shocks and any ride height change and the balance of damping front to rear adjusted.
Just replacing one ends shocks will take some time to get the adjustments right, which shocks do you have front and rear now?
Ok late reply. They were protech, so I'm matching the rear. The spring/dampers units are turning up circa Friday at my Dads (proven mill pond flat, horizontal garage floor) and I'll fit them. In the meantime I've been running the fronts down a few clicks.
Apart from ride height, inputting an offside bias (front and rear) for driver weight and a suirable rake (14 - 15 mm across the length of the sills?) Is there anything else i can consider?
Ps probably going for horizontal across the axles
Apart from ride height, inputting an offside bias (front and rear) for driver weight and a suirable rake (14 - 15 mm across the length of the sills?) Is there anything else i can consider?
Ps probably going for horizontal across the axles
Adjust the front dampers slightly stiffer than the rears.
Start in the middle, test, adjust stiffer or less always keeping the rear 3-4 clicks softer. Keep testing on the same bit of country road and you will feel the difference.
Agreed 10mm or thereabouts rake.
I always set up a few mm higher on the offside to allow for the driver as my car is generally driven, driver only.
Start in the middle, test, adjust stiffer or less always keeping the rear 3-4 clicks softer. Keep testing on the same bit of country road and you will feel the difference.
Agreed 10mm or thereabouts rake.
I always set up a few mm higher on the offside to allow for the driver as my car is generally driven, driver only.
Got protechs on mine and i have mine 158mm at the front and 175mm at the rear with -2 from full stiff at the front and -3 from full stiff at the rear.
That's running 26psi tires front and 29psi rear.
Mine was setup with neutral handling with A/B roads in mind.
Had mine a little higher than usual as my village has a million speed humps and at high speed an a B road i used to get some rubbing on the rear on very uneven roads.
Took mine to Centre Gravity for the setup, well worth the spend IMO.
That's running 26psi tires front and 29psi rear.
Mine was setup with neutral handling with A/B roads in mind.
Had mine a little higher than usual as my village has a million speed humps and at high speed an a B road i used to get some rubbing on the rear on very uneven roads.
Took mine to Centre Gravity for the setup, well worth the spend IMO.
potash4 said:
Got protechs on mine and i have mine 158mm at the front and 175mm at the rear with -2 from full stiff at the front and -3 from full stiff at the rear.
That's running 26psi tires front and 29psi rear.
Mine was setup with neutral handling with A/B roads in mind.
Had mine a little higher than usual as my village has a million speed humps and at high speed an a B road i used to get some rubbing on the rear on very uneven roads.
Took mine to Centre Gravity for the setup, well worth the spend IMO.
Seems high (for the reason you state) but also more rake than I would be comfortable with on a rwd car with 350 bhp and no TC. That's running 26psi tires front and 29psi rear.
Mine was setup with neutral handling with A/B roads in mind.
Had mine a little higher than usual as my village has a million speed humps and at high speed an a B road i used to get some rubbing on the rear on very uneven roads.
Took mine to Centre Gravity for the setup, well worth the spend IMO.
Lots of air in those rear tyres won't help when it comes to the rear getting loose - unless of course you want it too.
Is it set up for drifting on A/B roads
Ok after weeks of fettling I’ve gone for 5 5/16 - 5 3/4 taken from the sills (happy that the chassis out riggers are consistent with the fibreglass). Weighted the car with 55 kg on offside seat and 20kg on nearside (I weigh 75 kg).
Looks right and am happy with the relative roll heights and their effect on the balance front to rear (with 2 - 3 clicks difference on the dampers). Tried a smaller rake and was less happy with the front end in a straight line).
Exploring the dampers settings and am pleased that a supple rear gives better traction and not to much wobble under stress, even though it feels a "bit bouncy'. Surprised that hard settings are causing resonance if not by the tighter response at higher speeds on smoother roads.
The higher road height suggest earlier is useful (thanks guys) and allows me to contemplate two damper settings, having fitted the rear shocks with the damper dial facing outwards, adjustment is a pop; the front face inwards (hummmm, not sure a 180 will help).
The fundamental situational problem is urban living and open road driving (track time is infrequent).........however I'm loving the journey in all senses.
Ps got my first ever ticket, an SP70 the other day, used to pride myself on keeping my eyes open........I blame complacency due to sh*ty curtesy car....not my driving obviously
Looks right and am happy with the relative roll heights and their effect on the balance front to rear (with 2 - 3 clicks difference on the dampers). Tried a smaller rake and was less happy with the front end in a straight line).
Exploring the dampers settings and am pleased that a supple rear gives better traction and not to much wobble under stress, even though it feels a "bit bouncy'. Surprised that hard settings are causing resonance if not by the tighter response at higher speeds on smoother roads.
The higher road height suggest earlier is useful (thanks guys) and allows me to contemplate two damper settings, having fitted the rear shocks with the damper dial facing outwards, adjustment is a pop; the front face inwards (hummmm, not sure a 180 will help).
The fundamental situational problem is urban living and open road driving (track time is infrequent).........however I'm loving the journey in all senses.
Ps got my first ever ticket, an SP70 the other day, used to pride myself on keeping my eyes open........I blame complacency due to sh*ty curtesy car....not my driving obviously
I've been through a large number of 'trial' specs with my car, from new, for road and track. Neill Anderson who designed the suspension of this and the Sag was most helpful, and Guy who runs Nitron. Happy to share what I found.
Many owners have individual preferences for ride comfort vs firm handling of course, but several aspects are common throughout to get the best handling from the T350 in all conditions IMHO.
24psi is the correct pressure for any tyres on the T350, this is weight-related so doesn't change. If on track the tyres will heat up and need reducing back to 24 - again extensively tested by me and many others!
There needs to be more neg camber on fronts than backs, but rears benefit from more than standard with virtually no effect on tyre wear.
Rake was always a challenge for Neill, he said the rear roll centre was slightly too high relative to the front and he couldn't resolve that within the cost parameters of the design of the chassis. So the answer if you wanted optimum handling was to run it as low as you could at the rear to bring the lower wishbone arms close to parallel with the road. However you need firmer springs for that or you'll be on the bump-stops a lot (which are smaller & less lot developed than on the Sagaris), around 350-400lb rears and stiffer fronts. The front should be a sensible height - the dealers asked for it to be lower initially which caused poor handling. My heights & rake are 165mm front, 170mm rear measured up to the chassis tubes behind front wheels/in front of rears.
My handling eventually was quite transformed and has since been able to hold a drift very nicely with no snappiness on power or lift-off, helped to some degree by a very progressive Quaife torsen diff (which also helpfully gives no limited slip effect when torque is removed). Corner-weight adjustment will optimise the setup under hard braking as many will know, if your springs have adjustable platforms and you have a motorsport garage nearby to do it, with a driver on board.
Hope that's useful.
Many owners have individual preferences for ride comfort vs firm handling of course, but several aspects are common throughout to get the best handling from the T350 in all conditions IMHO.
24psi is the correct pressure for any tyres on the T350, this is weight-related so doesn't change. If on track the tyres will heat up and need reducing back to 24 - again extensively tested by me and many others!
There needs to be more neg camber on fronts than backs, but rears benefit from more than standard with virtually no effect on tyre wear.
Rake was always a challenge for Neill, he said the rear roll centre was slightly too high relative to the front and he couldn't resolve that within the cost parameters of the design of the chassis. So the answer if you wanted optimum handling was to run it as low as you could at the rear to bring the lower wishbone arms close to parallel with the road. However you need firmer springs for that or you'll be on the bump-stops a lot (which are smaller & less lot developed than on the Sagaris), around 350-400lb rears and stiffer fronts. The front should be a sensible height - the dealers asked for it to be lower initially which caused poor handling. My heights & rake are 165mm front, 170mm rear measured up to the chassis tubes behind front wheels/in front of rears.
My handling eventually was quite transformed and has since been able to hold a drift very nicely with no snappiness on power or lift-off, helped to some degree by a very progressive Quaife torsen diff (which also helpfully gives no limited slip effect when torque is removed). Corner-weight adjustment will optimise the setup under hard braking as many will know, if your springs have adjustable platforms and you have a motorsport garage nearby to do it, with a driver on board.
Hope that's useful.
Edited by tail slide on Tuesday 1st August 23:21
Gassing Station | Tamora, T350 & Sagaris | Top of Page | What's New | My Stuff