Odd suspension question

[michaelw]

I have had my '95 car for 3 odd years now and when I first got it I noticed the car almost feels like it is understeering when you apply the power. If you are going round a right or left or hand corner and hold the stering on a certain ammount of lock when you accelarate the radius of the turn gets wider. When you back off it goes back to the trajectory it was on. The speed you take teh corner is irrelavant although it is more pronounced on long corners whatever the speed if that makes sense.

It does feel very odd to me and I had the tracking checked out. The garage adjusted the tracking etc it and all was OK except the caster. It appears that the closest they can get the caster on one side is 5.5 degrees and the other 7.5. This is effectively the limit at each end if you see what I mean i.e. they can make it 8.0 and 5.0 or whatever. I think this might be a red herring though and anyway the caster adjusters have now both seized.

My question is "Do they all do that sir" or could is there something wrong. It has been suggested that it could be the LSD but I have a Caterham with a very stiff LSD and that doesn't do this at all and no other car I have driven does it either as far as I can remember.

Sorry for the long drawn out explanantion but I find it difficult to describe. One part of me hopes there is something wrong as it does detract from the car IMHO but saying that I have got used to driving around it now.

Many thanks,


Michael.

[britlude]

so basically it's 'pushing on' if you apply power in a corner.....

does sound like the power being planted down, rears gripping nice and squarely and the nsx ready to pounce when the corner straightens!!!!

could be many factors like front tyre pressure too high, rear too low, tyres knackered, stock widths/offset wheels, tired dampers, etc...!!! castor is usually more related to the steering self-centering...

if it's any help, mine does it, and I love it!!!!

[simonprelude]

Sounds OK ish to me.

Can they not get the allignment correct due to seized bushes or something like that ??

I organised a full geometry and allignment day for S2000 owners (well Nick did but using my house) using a mobile company with very good equipment, the same as McLaren use apparently.

They said that they would be more than happy to arrange a day for NSX owners so if anyone is interested then let me know and we can start a new thread.

But basically we would probably need 4 people and prices would be between £150 and £200 per car.

Mine badly needs doing as was previously set up for someone elses personal preference which I really don't get on with at high speed.

[michaelw]

Thanks for the replies.

It has got aftermarket wheels and has spacers on the front (don't like that) and tellingly it has 2 spacers in the boot which may explain the problem although I am not sure whether they came off the front or rear. I will measure the offset. I didn't think that would do it but will try it out.

The caster is adjusted by moving the 2 castings that go to make up the compliance thing relative to each other and both these have seized and I think were £1200 each side + VAT - ouch.

I am going to get someone other than a dealer to look at it as all they said was you need to replace compliance thing but didn't appreciate that even doing that wouldn't get the caster back in tolerance. Someone has also suggested that the suspension can move on its mountings if given a bang.

As I said I have got used to it but its just a bit disconcerting if you have to come off the throttle half way through a corner as it does change line quite dramatically and yes I know you shouldn't do that.


Michael.

Edited to say: Simon, I would be very interested but would need to get the adjusters all free first if I can.

[simonprelude]

Try a regular application of duck oil on these, they may free up.


The caster is adjusted by moving the 2 castings that go to make up the compliance thing relative to each other and both these have seized and I think were £1200 each side + VAT - ouch.

[OLDMNSX]

Thanks for the replies.

It has got aftermarket wheels and has spacers on the front (don't like that) and tellingly it has 2 spacers in the boot which may explain the problem although I am not sure whether they came off the front or rear. I will measure the offset. I didn't think that would do it but will try it out.

Edited to say: Simon, I would be very interested but would need to get the adjusters all free first if I can.

Definitly get all adjustable parts free prior to trying to do an alignment. Leave the sledge hammer in the closet!!!!! Multiple applications of a good penetrating oil. Do you have any PB Blaster?

I am no suspension professional, but a few things that I have learned over the years.

1. You can do an alignment to specs and then install a set of spacers, or different wheels and put the car back on the alignment rack and the readings change considerably.

2. Your wheel offset / spacer combination may not allow the suspension adjustments to come into allowable range.

3. The factory suspension setup will set the rear wheels with a lot of negative camber (the top of the tires tilt to the inside of the car) so wears out the inside edge of the rear tires prematurely. I have my rear tires just about flat for maximum wear. Tires cost too much. That can also be translated as, "I'm CHEAP"

4. I have noticed that I can push the front end out from under the car in a corner by applying too much power. i.e. the car wants to go straight instead of turning. If I just let of the gas a little it gets back into the corner. The front end either needs more weight, or more rubber on the road or both. I have to keep telling myself that my NSX isn't a Formula 1 car!

I know that there are people out there that know a lot more about this than I do, PLEASE SPEAK UP. If I said something that was wrong here let's get it fixed. I have thick skin and I'm always willing to learn.

Brad

[cas]

When applying power going round a curve you generate centrifugal force pushing out. However if it is really large it suggests that your front shocks/ coils are a bit soft and the front is lifting - does the front lift when you apply power - you should see this even in a straight line.

[markc]

Hi Brad,

W.R.T to the comment that "Your wheel offset / spacer combination may not allow the suspension adjustments to come into allowable range," I was told that this does not in fact effect the measurements or the ability to set them.

Having thought about it a logically as I can, I think I do now see why this is the case.

It is however likely that removing and refitting the wheels or even driving the car between taking suspension measurements will show small changes and this would also show up if you changed the wheels or installed spacers.

Cheers

Mark

[michaelw]

Thanks again, loads to think about there. I have tried lubricating them but unfortunately got them free and they then siezed solid as I moved them to get them more free. I was then told I shouldn't have done that as the ally will have "picked up" and a small poece of ally has probably rolled from one casting to the other and wedged it solid - that's the end of that then.

Brad,

I am going to check the offset with and try and work out if I need teh spacers or not and get the suspension checked out. I hadn't thought that the suspension will need to be adjusted again so thanks. I am not sure it is sending the caster out of range though as one side is OK whereas the other isn't but more than happy to be corrected on this.

I should have said that I have thought about this for ages and have had people who sort of know hat they are doing help me out but all to no avail. I will let you know when/if anything comes of it.


Michael.

[Senninha]

It appears that the closest they can get the caster on one side is 5.5 degrees and the other 7.5. My question is "Do they all do that sir" or could is there something wrong.


I had the tracking checked on mine last week and the castor angles are very similar, LF at 5.8 and RF at 7.4. I was told that there was little by way of adjustment as this is done by an unusual shaped adjuster that limits what can be done :confused:

As for the 'pushing on' in the corners, have you checked the obvious things like tyre condition and pressure? Old tyres that have gone hard could be a factor if you are low mileage user as could over inflated fronts?

If you get the castor angles adjusted please let me know as I'll be going back to challenge the info I've been given.

HTH

[michaelw]

Thanks again for all the replies. It is definately not understeer as it happens well well below the limit as much as close to the limit, the tyres are fairly new and I use the car every day and it has been like this for 3 years now and I go through stages of forgetting about it.

Senninha,

Mine is LF 5 05 and RF 7 28 so it looks like we could have the same problem. I did watch teh guy do the tracking and he talked me through it. I will try and explain.

The camber is adjusted with a off-centre adjuster on the bottom wishbone in conjunction with what I see as the caster adjuster which is similar in that it is a off-centre adjuster but this rotates and moves the front of the botom wishbone sort of diagonally i.e. neither in/out or backwards/forwards if that makes sense.

If you can imagine a round disk with a hole drilled off-centre and as this rotates in the housing it moves whatever is attached through the off-centre hole. They are adjusted by another hexaganol hole which you turn with an allen key. Thats very difficult to picture from the rubbish explanation but if you look at where the bottom wishbone attaches to the inboard side of the car front and rear from underneath you will see what I mean.

Anyway the guy rotated this adjuster from one limit to another and he could only go from something like 4 20 to 5 05 or whatever but if you adjust the camber it also changes the caster if you see what I mean. The whole compliance adjuster is bolted to the car and I have wondered whether it has had a belt on my car and the whole assembly moved backwards on its bolts. This would tie in with the problem being on the kerb side as well.

Anyway sorry for the long winded explanation I hope it helps and, as you have probably noticed, I have been told conflicting things and don't really know what I am talking about .


Michael.