Need all your help guys & gals
Discussion
It seems positively impossible to find what the ride height should be for an S.
I know later cars ran higher, and I am sure the V8S and S4 were different again.
The help I am after means you'll need to get under your car with a measuring device as I want to build a picture of what height people are running their cars at.
The suggested measuring points are....
Rear - Centre of outer trailing arm bolt to floor
Front - Centre of front wishbone bolt to floor
If people are running non standard wheels and tyres please give details.
Mine is still running too low at the front and I'm interested to compare....that's all folks !!
Cheers
Mark
I know later cars ran higher, and I am sure the V8S and S4 were different again.
The help I am after means you'll need to get under your car with a measuring device as I want to build a picture of what height people are running their cars at.
The suggested measuring points are....
Rear - Centre of outer trailing arm bolt to floor
Front - Centre of front wishbone bolt to floor
If people are running non standard wheels and tyres please give details.
Mine is still running too low at the front and I'm interested to compare....that's all folks !!
Cheers
Mark
Mark
Don't know if this will help, but was sorting out a couple of things on my S4 this evening, so took the opportunity to roughly measure the points you mentioned.
Front w/bone bolt to floor 192mm
Rear trailing arm bolt 280 n/s 270mm o/s !!!
Tyres - Pirelli P6000
Think I'll have to get this looked at as well!
Btw, the car is booked in for a 12,000ml service at Peninsular on the 6th so could give you a report afterwards. I've not used them before but all the pointers suggest they are OK.
Hope the above helps
Cheers
Graham
Don't know if this will help, but was sorting out a couple of things on my S4 this evening, so took the opportunity to roughly measure the points you mentioned.
Front w/bone bolt to floor 192mm
Rear trailing arm bolt 280 n/s 270mm o/s !!!
Tyres - Pirelli P6000
Think I'll have to get this looked at as well!
Btw, the car is booked in for a 12,000ml service at Peninsular on the 6th so could give you a report afterwards. I've not used them before but all the pointers suggest they are OK.
Hope the above helps
Cheers
Graham
I'm sure you're right and it probably varies between
models and from year to year, maybe depends what day
of the week it was made for all I know. For what it's
worth I have quite a lot of readings from the V8S,
from the original standard settings up to the
current highly non-standard ones.
Measuring chassis height leaves quite a few variables
in there. If you're3 comparing different cars it
may be easier to work with damper lengths as this
takes out a lot of the variability from tyre size,
pressure, tread depth, camber and so on. It is also
easier to work with when it comes to specifing spring
and damper lengths.
As standard my V8S dampers were around 325mm between
centers at normal ride height and the fronts were
similar or maybe 5mm shorter. That was with the
original springs which were roughly 210/300 lb/in
front and 180/270 lb/in rear. Figures I've been
given for V6 cars suggest they may have used stiffer
springs but I can't say for sure.
I guess the ground clearance is the most important
factor for most V6 drivers, but there are several
other factors to bear in mind. The amount of bump
travel required all round depends on bump stops, spring
rates, damper/arb settings and how the car is driven
- this limits how far you can lower the car. As you
lower the front the roll center drops significantly
(reducing the effective front roll stiffness) and you
get increasing amounts of roll- and bump-induced
camber change. Incidently, whenever you change the
front ride height remember to reset the camber. From
the aerodynamic point of view you want the front as
low as possible and the rear relatively high. In order
to reduce axle tramp it is helpful to set it so the
trailing arm pivot axis intersects the rear center
line at axle height. There are lots of other things
to check if you are suffering axle tramp btw, but
that's another story ...
Cheers,
Peter Humphries (and a green V8S)
models and from year to year, maybe depends what day
of the week it was made for all I know. For what it's
worth I have quite a lot of readings from the V8S,
from the original standard settings up to the
current highly non-standard ones.
Measuring chassis height leaves quite a few variables
in there. If you're3 comparing different cars it
may be easier to work with damper lengths as this
takes out a lot of the variability from tyre size,
pressure, tread depth, camber and so on. It is also
easier to work with when it comes to specifing spring
and damper lengths.
As standard my V8S dampers were around 325mm between
centers at normal ride height and the fronts were
similar or maybe 5mm shorter. That was with the
original springs which were roughly 210/300 lb/in
front and 180/270 lb/in rear. Figures I've been
given for V6 cars suggest they may have used stiffer
springs but I can't say for sure.
I guess the ground clearance is the most important
factor for most V6 drivers, but there are several
other factors to bear in mind. The amount of bump
travel required all round depends on bump stops, spring
rates, damper/arb settings and how the car is driven
- this limits how far you can lower the car. As you
lower the front the roll center drops significantly
(reducing the effective front roll stiffness) and you
get increasing amounts of roll- and bump-induced
camber change. Incidently, whenever you change the
front ride height remember to reset the camber. From
the aerodynamic point of view you want the front as
low as possible and the rear relatively high. In order
to reduce axle tramp it is helpful to set it so the
trailing arm pivot axis intersects the rear center
line at axle height. There are lots of other things
to check if you are suffering axle tramp btw, but
that's another story ...
Cheers,
Peter Humphries (and a green V8S)
I'm sure you're right and it probably varies between
models and from year to year, maybe depends what day
of the week it was made for all I know. For what it's
worth I have quite a lot of readings from the V8S,
from the original standard settings up to the
current highly non-standard ones.
Measuring chassis height leaves quite a few variables
in there. If you're comparing different cars it
may be easier to work with damper lengths as this
takes out a lot of the variability from tyre size,
pressure, tread depth, camber and so on. It is also
easier to work with when it comes to specifing spring
and damper lengths.
As standard my V8S dampers were around 325mm between
centers at normal ride height and the fronts were
similar or maybe 5mm shorter. That was with the
original springs which were roughly 210/300 lb/in
front and 180/270 lb/in rear. Figures I've been
given for V6 cars suggest they may have used stiffer
springs but I can't say for sure.
I guess the ground clearance is the most important
factor for most V6 drivers, but there are several
other factors to bear in mind. The amount of bump
travel required all round depends on bump stops, spring
rates, damper/arb settings and how the car is driven
- this limits how far you can lower the car. As you
lower the front the roll center drops significantly
(reducing the effective front roll stiffness) and you
get increasing amounts of roll- and bump-induced
camber change. Incidently, whenever you change the
front ride height remember to reset the camber. From
the aerodynamic point of view you want the front as
low as possible and the rear relatively high. In order
to reduce axle tramp it is helpful to set it so the
trailing arm pivot axis intersects the rear center
line at axle height. There are lots of other things
to check if you are suffering axle tramp btw, but
that's another story ...
Cheers,
Peter Humphries (and a green V8S)
models and from year to year, maybe depends what day
of the week it was made for all I know. For what it's
worth I have quite a lot of readings from the V8S,
from the original standard settings up to the
current highly non-standard ones.
Measuring chassis height leaves quite a few variables
in there. If you're comparing different cars it
may be easier to work with damper lengths as this
takes out a lot of the variability from tyre size,
pressure, tread depth, camber and so on. It is also
easier to work with when it comes to specifing spring
and damper lengths.
As standard my V8S dampers were around 325mm between
centers at normal ride height and the fronts were
similar or maybe 5mm shorter. That was with the
original springs which were roughly 210/300 lb/in
front and 180/270 lb/in rear. Figures I've been
given for V6 cars suggest they may have used stiffer
springs but I can't say for sure.
I guess the ground clearance is the most important
factor for most V6 drivers, but there are several
other factors to bear in mind. The amount of bump
travel required all round depends on bump stops, spring
rates, damper/arb settings and how the car is driven
- this limits how far you can lower the car. As you
lower the front the roll center drops significantly
(reducing the effective front roll stiffness) and you
get increasing amounts of roll- and bump-induced
camber change. Incidently, whenever you change the
front ride height remember to reset the camber. From
the aerodynamic point of view you want the front as
low as possible and the rear relatively high. In order
to reduce axle tramp it is helpful to set it so the
trailing arm pivot axis intersects the rear center
line at axle height. There are lots of other things
to check if you are suffering axle tramp btw, but
that's another story ...
Cheers,
Peter Humphries (and a green V8S)
Peter,
As you may remember I have your old (prototype) Gaz dampers at all four corners now. What I don't seem to be able to sort is the front ride height. It sits too low on the o/s even with me adjusting it up. Both front springs are apparently fine but both front wheels catch the wheel arches on full lock.
They also catch if in a bend hard and hit a bump. This can't go on, unfortunate as the handling is great with brilliant turn in which I'm sure I'll lose if I go higher again at the front.
I need to get this set up right ready for Zolder !!
Are you going to feel generous in Belguim and take me for a flying lap to see what you can really do in a S ??
Cheers
Mark
As you may remember I have your old (prototype) Gaz dampers at all four corners now. What I don't seem to be able to sort is the front ride height. It sits too low on the o/s even with me adjusting it up. Both front springs are apparently fine but both front wheels catch the wheel arches on full lock.
They also catch if in a bend hard and hit a bump. This can't go on, unfortunate as the handling is great with brilliant turn in which I'm sure I'll lose if I go higher again at the front.
I need to get this set up right ready for Zolder !!
Are you going to feel generous in Belguim and take me for a flying lap to see what you can really do in a S ??
Cheers
Mark
quote:
It sits too low on the o/s even with me adjusting it up.
Measured how? I guess you know you can't rely on the bodywork height!
Happy to take you for a spin round Zolder, its a great circuit. There is some in-car video from 2001 at www.roop.ik.com.
Cheers,
Peter Humphries (and a green V8S)
quote:
If I were to stiffen the ARB bushes would this help prevent some of the issues I am having ???
Poly bushes to replace the original rubber ones ??
No. They don't change the geometries just prevent complience movement.
There is absolutely no standard ride height for these cars. One reason is that the chassis changed, the shocks chnaged and the springs changed. The bodies were not fitted straight...
The only way to measure the height is from a chassis pick up point because you want to measure from somewhere that doesn't change. If you need more clearance then it is possible that you may need different length springs to get that. This is not uncommon as the body fit on the chassis is not that great and there is often plenty of variation. Fortunately new springs are not expensive for those shocks.
If you adjust the ride height up and you find that the handling is not as good then you need to make a choice: either lower it again and take the consequences or leave it as is. I suspect that raising it slightly will not affect the handling noticeably.
The other things: is this a sign that you have something else wrong? Are you sure the bump is the wheel hitting the bodywork and not the shock hitting its bump stop? Have you tried increasing the shock stiffness?
I have adjusted the damper stiffnes to try and stop it. It is definitely the wheel catching the body and not the damper on the bump stops (evidenced on wheel arch)
The body fit is wrong and not square. The ride height hadn'y been changed from Peters car I suspect when they were fitted to mine as it looked a little like a 'hot rod' when I picked it up !!
I have lowered the rear and am just about happy with that. It just seems I am having to raise the front a large amount to get it to stop catching the bodywork.
Cheers for the suggestions I will return to it today and raise it some more and see how I get on.
Cheers
Mark
The body fit is wrong and not square. The ride height hadn'y been changed from Peters car I suspect when they were fitted to mine as it looked a little like a 'hot rod' when I picked it up !!
I have lowered the rear and am just about happy with that. It just seems I am having to raise the front a large amount to get it to stop catching the bodywork.
Cheers for the suggestions I will return to it today and raise it some more and see how I get on.
Cheers
Mark
quote:
quote:
It sits too low on the o/s even with me adjusting it up.
Measured how? I guess you know you can't rely on the bodywork height!
Happy to take you for a spin round Zolder, its a great circuit. There is some in-car video from 2001 at www.roop.ik.com.
Cheers,
Peter Humphries (and a green V8S)
Big thanx Peter, I look forward to that a lot. May even buy you a beer !!
See you at Zolder..
Mark
quote:
Peter,
As you may remember I have your old (prototype) Gaz dampers at all four corners now. What I don't seem to be able to sort is the front ride height. It sits too low on the o/s even with me adjusting it up. Both front springs are apparently fine but both front wheels catch the wheel arches on full lock.
They also catch if in a bend hard and hit a bump. This can't go on, unfortunate as the handling is great with brilliant turn in which I'm sure I'll lose if I go higher again at the front.
I need to get this set up right ready for Zolder !!
Thinking about this a bit further, I know how difficult it can be to get to grips with this sort of problem and maybe as somebody who has 'been there, done that' I can help. Sorry this is a bit long-winded, the 99.9% people who aren't interested in suspension setup should probably not bother reading any further ...
How much clearance you need depends on various factors like what spring/damper rates you have, what size wheels, what sort of roads you drive on and how you chuck it about. As you know, when I had those dampers on my V8S I had them wound up fairly firm which cuts down the amount of body motion, and I've got rigid ARB mounts which reduces roll somewhat. Also I tend to compete on reasonably smooth surfaces and don't chuck the car about as violently as I used to. I deliberately modified my driving technique to avoid excessive combinations of roll and dive which show up this sort of problem. All these factors would let me run the car lower without running out of bump travel.
If you want to do this properly you would be well advised to read a good book on car suspension, Fred Puhn's book is pretty good if you ignore the stuff about live axles and cross ply tyres! But in case you just want to get it to a good reasonable road setting, here's Pete's fifty cent course on suspension setup:
Suggest you start by getting the car level side-to-side. You *cannot* do this by eye. You need to find/make a completely flat surface, then measure the car up. It is surprisingly difficult to get a completely flat surface, half an inch change in height over the length of the car is impossible to see, so you will need to use a spirit level between the contact patches. Ideally you want a completely level surface (all four wheels at the same height) but all you really *need* to sort the ride height is a FLAT surface .e. no twist in it. If you're planning to check the camber as well then it *does* need to be level as well as flat. If it's fairly flat you can make up a small difference by packing up one wheel. If you know somebody with a workshop with a well prepared floor this can save you a lot of time here. Suggest you remember exactly where you did it and how much packing you needed in case you need to do it again in future. Also make quite sure all the tyre pressures are spot on and no obvious differences in tyre side to side, you are going to feel a right berk if you set it up with a flat tyre!
Once the wheels are on a flat surface, with the sort of spring rates you're using you can measure the corner wights by measuring the length between spring seats, and measure the corner heights by masuring the length between damper mounting bolts. If you can measure these dimensions within a mil or so that's fine, ideally go round the car twice and average the readings.
Set the left and right spring seats at the same position on the damper (front and rear) and with the car on your level surface measure the spring lengths to check there is no twist in the car. They won't be identical side-to-side, but the ratio of left-to-right should be the same at both ends. If not, this is a problem you need to sort before you do anything else. Either you have a duff spring, or a bent chassis, or your surface isn't as flat as you thought.
Assuming you have not got any measurable twist, the next step is to level the ride height side-to-side. Measure the damper lengths to see which side is low. Since the weight is almost exactly central on a typial S this is probably close enough to go with as it is, but if you do need to adjust it wind the front and rear spring seats on that side to bring it up to the height of the other side. If you do front and rear together you can do this without reintroducing twist, but remember the rear dampers run at higher leverage than the front (1.7 vs 1.4) so will need correspondingly less adjustment. After you've got it level, recheck there still isn't any twist, if the ride height was a long way out the ARB may have given you some twist which will now be apparent. Depending how far out it was in the first place you might want to go round a couple of times to get it completely level with no twist. But as I said, if you have a straight chassis and start with all the spring seats set the same I would be surprised if you had to make any significant adjustment.
Now you're ready to start playing with the ride height. This is largely a matter of trial and error to find how much travel/clearance you need in normal driving. If it tends to bottom out, your main options are fit stiffer springs, stiffen the dampers up, move the bodywork out the way or increase the ride height. It's always a compromise, but don't forget you have other options than just increasing the ride height.
When you adjust the ride height always adjust left and right spring seats together by the same amount to ensure you don't introduce twist or roll. If you're running it as low as possible and in danger of running out of travel you also need to make sure the suspension bottoms out on the bump stops before the wheel hits the body, and bear in mind the bump stops are flexible and will crush half an inch or so on impact. If you need to adjust the bump stops you can put C section spacers underneath (Merlin sell them, or make your own) or get longer bump stops. But you should have the car set high enough that you don't normally hit the bump stops as this strains the suspension, gives an uncomfortable ride and *really* messes up the car's handling!
Assuming you have got the initial settings right you can change the ride height just by adjusting the left and right spring seats the same amount, you don't need to go through the palaver of re-checking everything. But if you have made several adjustments or have any doubt whether you turned that spring seat clockwise or anticlockwise last night when you were as tired as a newt, it is worth rechecking the whole thing again. If you do check it, it is essential that you do it on completely flat ground or the results are meaningless. The check itself is a five minute job once you've got the car on a flat surface.
If you change the front ride height significantly you will need to correct the camber afterwards, as you lift the car you lose negative camber. Incidentally, running with the wrong camber will probably make more difference than the change in ride height, if you found the car doesn't feel as good after you increased the ride height this may well be what you're feeling. I'm running 2.8 degrees -ve camber but you will probably want about half this.
You can check and adjust the front camber yourself quite easily, you can buy commercial 'spirit level' type camber guages or make your own using a plumb line. If you're doing this, it is essential that the car is absoluely level so do it while you've got it on your level floor.
Hope this makes sense and you get it sorted. Feel free to give me a bell if you want to talk it through, number is in Sprint under helplines.
PS sorry the above is so long winded!
Cheers,
Peter Humphries (and a green V8S)
quote:
Once the wheels are on a flat surface, with the sort of spring rates you're using you can measure the corner wights by measuring the length between spring seats, and measure the corner heights by masuring the length between damper mounting bolts. If you can measure these dimensions within a mil or so that's fine, ideally go round the car twice and average the readings.
quote:
Peter,
Will there be any kind of ambient weight transfer left as I get out of the car. Am I best to bounce each corner a couple of times to make sure the car has settled level before I start. I doubt there would be but we are talking millimetres here ???
quote:
Set the left and right spring seats at the same position on the damper (front and rear) and with the car on your level surface measure the spring lengths to check there is no twist in the car. They won't be identical side-to-side, but the ratio of left-to-right should be the same at both ends.
quote:
By this you mean that if spring lengths are different then the difference should be equal front and rear on that side to compensate for any greater weight on that side ?
quote:
Assuming you have not got any measurable twist, the next step is to level the ride height side-to-side. Measure the damper lengths to see which side is low. Since the weight is almost exactly central on a typial S this is probably close enough to go with as it is, but if you do need to adjust it wind the front and rear spring seats on that side to bring it up to the height of the other side. If you do front and rear together you can do this without reintroducing twist, but remember the rear dampers run at higher leverage than the front (1.7 vs 1.4) so will need correspondingly less adjustment. After you've got it level, recheck there still isn't any twist, if the ride height was a long way out the ARB may have given you some twist which will now be apparent. Depending how far out it was in the first place you might want to go round a couple of times to get it completely level with no twist. But as I said, if you have a straight chassis and start with all the spring seats set the same I would be surprised if you had to make any significant adjustment.
quote:
Rather than the car being level, what in fact you are doing is making sure the damper lengths correspond to each other ? You could still end up with the front being lower or the reverse but the lateral level would be correct ??
quote:
Now you're ready to start playing with the ride height. This is largely a matter of trial and error to find how much travel/clearance you need in normal driving. If it tends to bottom out, your main options are fit stiffer springs, stiffen the dampers up, move the bodywork out the way or increase the ride height. It's always a compromise, but don't forget you have other options than just increasing the ride height.
quote:
I will be replacing the ARB mounts with Poly bushes before I start this exercise.
quote:
When you adjust the ride height always adjust left and right spring seats together by the same amount to ensure you don't introduce twist or roll. If you're running it as low as possible and in danger of running out of travel you also need to make sure the suspension bottoms out on the bump stops before the wheel hits the body, and bear in mind the bump stops are flexible and will crush half an inch or so on impact. If you need to adjust the bump stops you can put C section spacers underneath (Merlin sell them, or make your own) or get longer bump stops. But you should have the car set high enough that you don't normally hit the bump stops as this strains the suspension, gives an uncomfortable ride and *really* messes up the car's handling!
quote:
This doesn't happen at the front I'm quite sure. The rear is a different matter though. I have the ride height set so that there is 4 fingers clearance to the body work from the top of the tyre. Rough as a badgers butt I know but a starter from the old set up. With this the dampers are very near to the bump stops and can't do anything but hit them. It does effect the handling and in my limited knowledge I reckon the Gaz dampers are too long. I have blown 2 pairs apart at the rear, neither of which were wound right down at all. These seem to be far better.
If I wind the height up at the rear then I loose -ve camber and wind up with wheels like a 2CV !
quote:
PS sorry the above is so long winded!
Sorry the reply seems even longer. As for the camber I will let some pro adjust that one. I need to get the suspension back to base settings and go again from there. I am happy with the handling at the moment generally I just think it can be improved and with the roads and driving style I have I can't keep having wheels rubbing body work !!
Cheers
Mark
quote:
Peter,
Will there be any kind of ambient weight transfer left as I get out of the car. Am I best to bounce each corner a couple of times to make sure the car has settled level before I start. I doubt there would be but we are talking millimetres here ???
Yes, it's worth bouncing all four corners to take out any stiction, I don't think you will need to jack the car up but if you do then roll it back and forward a few feet to allow it to adjust to the change in track width.
quote:
By this you mean that if spring lengths are different then the difference should be equal front and rear on that side to compensate for any greater weight on that side ?
Oh dear reading it back I don't think I described this very well. The weight on the spring is proportional to the deflection, i.e. the difference between its free length and its loaded length. Assuming the left and right springs are identical and the car's center of gravity is on the center line (and it should be close) then all you need to know is the left and right springs should be the same length, and if they aren't then the shorter one has more weight on it. To get 'zero twist' you want to have both front springs taking equal weight, and both rear springs taking equal weight.
quote:Yes absolutely.
Rather than the car being level, what in fact you are doing is making sure the damper lengths correspond to each other ? You could still end up with the front being lower or the reverse but the lateral level would be correct ??
quote:
This doesn't happen at the front I'm quite sure. The rear is a different matter though. I have the ride height set so that there is 4 fingers clearance to the body work from the top of the tyre. Rough as a badgers butt I know but a starter from the old set up. With this the dampers are very near to the bump stops and can't do anything but hit them. It does effect the handling and in my limited knowledge I reckon the Gaz dampers are too long. I have blown 2 pairs apart at the rear, neither of which were wound right down at all. These seem to be far better.
With my springs I had to put the spring seats as low as they'd go and the car was at a roughly standard ride height. I didn't notice any problem with the rears bottoming out. But if your springs are shorter/softer it could be you're running them lower than I was. How wide is your hand, three inches or so? That suggests you have the rear quite a bit lower than standard. How much clearance do you reckon there is on the rear dampers between the bump stop and the damper body? When you're looking at it, remember the wheel is at about 1.7:1 leverage to the damper, and the bump stop crushes half an inch easily, so if you have an inch of free travel, half an inch plus of bump stop deflection and multiply this by 1.7 the total wheel motion might be more than you think. If you really haven't got enough, don't be afraid to pick the car up half an inch, the camber change at the rear is relatively small (I think it comes out something like half a degree per inch) and you can easily adjust the camber at the front.
quote:Wow, better lay in some cross ply tyres then! If you don't mind taking a spanner to it, it is relatively simple to shim the rear hubs to get any camber you want. But if the ride height is within the normal sort of range then I would be surprised if the camber was that far out. What may be happening is you have dropped the car lower than normal and got used to the appearance and handling of the extra camber this gives. I find the V8S handles a lot better with the extra camber (and stiffer springs etc) but it definitely increases tramlining and kick back and you need to change toe-in settings and so on, for most people this is the wrong answer.
If I wind the height up at the rear then I loose -ve camber and wind up with wheels like a 2CV !
I think it would be well worth measuring your actual damper and spring lengths and camber angles, it is extremely difficult to do this by eye, especially via email! Can describe how to make a very simple DIY camber gauge if you're interested.
Cheers,
Peter Humphries (and a green V8S)
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