What does this adjust?

[michaelw]

Hi guys,

I have a question regarding the front compliance assembly. Sorry it is long and involved but it is difficult to explain.

When looked at from the side the compliance adjuster has a mushroom shaped casting half way up and this in turn is above another casting. The gap between these 2 castings is different from one side of the car to the other.

This effectively means that the complaince adjuster is higher one side of the car than the other (all apart from the bit attached to the chassis if you see what I mean). This means that the front mounts of the lower and upper wishbones and thus the angle of the wishbones to the road is different from one side of the car to the other.

This is much easier to see than explain.

Is this OK and if not can you adjust it? It looks as though it has a four pronged star shaped thing looking from underneath but whether that turns or not I can't say.

The caster on my car is 8 degrees one side and 4 the other and the caster adjusters are about in the same position if you see what I mean which would indicate that unless something is bent they are not the issue.

Please help before I have to explain this to someone else.

Many thanks,


Michael.

 

[titaniumdave]

Page 18-7 in the manual gives a very good discription of the adjustment that can be made to the front suspension and the order they need to be made in. Plus the pit falls of trying to do it with out the right tools.

I would take it to a good shop that is familiar with 4 wheel independent suspension cars, a Lotus shop maybe, the compilance links should have no effect on the alignment unless they are bent or broken, so any compitent shop should be able to deal with the alignment.

Check out the FAQ section about alignment, there is a wide range of options depending on the trade off between performance and tire wear. The NSX is very sensitive to minor changes in alignment as far as it's handling and general road feel from my experience.

 

[michaelw]

Thanks for that, I had looked at the manual and it didn't mention anything about this anywhere. All other parts it goes into great detail but not this.

It would effect the ride height but I don't know what else and whenver I speak to anybody over here (UK), they say they don't touch it and have no idea what it does.

It just worries me that the LH and RH don't match up and the car steers oddly.

Many thanks,


Michael.

 

[V12NSX]

Michael,
Not sure which part you are describing to us, but if the caster is out, it's easy enough to fix. Trouble is, most alignment shops do not know how to do this and their computers don't tell them either. Print the pages for alignment and take it to them. To set the caster requires loosening two nuts and using an allen wrench to turn the adjusting cam. Of course, you have to adjust everything else in the proper order as well.

S.L.

 

[michaelw]

No I don't think I would understand judging by my description either. One more go.

The compliance adjuster is bolted to the car at a fixed point, but the part of the compliance adjuster that the wishbones are attached to can be adjusted up and down by the looks of things.

This means that on my car the distance between the front of the wishbone and the ground is greater on the left-hand side than the right-hand side. In other words one wishbone is say 1.5 degrees away from horizontal, looking from the side of the car, and the other is say 2 degrees (those measurements aren't correct, it is just to give you idea).

The reason I want to know about this is that here in the UK I live near one of the biggest NSX dealers and they take the cars to the local tyre fitters. I am sure they are fine but have a feeling my car has been altered from factory in a way not even the dealer knows about.

If you are still reading thanks very much for persevering Any guidance would be greatly received.

Many thanks in advance,


Michael.

 

[j14nsx]

Who have you taken the car to?

Do you know about the NSXCB? www.nsxcb.co.uk

There are plenty of UK owners that know where to take their cars to for alignment. There's a place in Southampton, that makes alignment equipment. The guy that does alignments there also is a NSX trained mechanic.

 

[Larry Bastanza]

I have followed this since the morning and have been trying to understand it. Your last post helped enough to send me to the service manual. I agree with V12NSX you need to get the caster set correctly. EVEN is more important then absolute values, but you should try to achieve the 8 degrees on both.

But.... I do not think this is the main issue, I think you may have a ride height difference to deal with. I would check the ride height and look at your springs carefully. Do you have an OEM Setup, aftermarket??

HTH,
LarryB

 

[michaelw]

J14NSX, I have seen NSXCB now but only came acroos it recently - I will keep an eye on it. I was going to post re alignment but noticed someone else beat me to it. I was going to try Micheldever but I think I may try the Southampton guy as he sounds as though he may be able to help especially with his Honda knowledge, thanks very much.

Larry, I totally agree and am going to get it tracked but just wanted to get the low down before I do that. I think you are right, the ride height is out but can't see how to adjust it in the manual (I won't be attempting it though).

I am pretty sure the car is standard as all looks the same as the manual, nothing looks aftermarket under there and the ride height looks fairly standard.

Thanks again for all the replies,

Michael.

 

[Larry Bastanza]

The ride height is not adjustable. It is based on the spring length/position, unless you have adjustable coil overs (aftermarket).

BTW: If the springs are aftermarket, even if the height looks fairly standard, some brands do sag unevenly over time.

Best of Luck.

LarryB

 

[Gerard van Santen]

Compliance Pivot

What is the purpose of the compliance pivot. Here is an explanation:

For good ride quality and a minimum of steering kickback, particularly over transverse ruts, it is important to allow the front wheels to move rearwards slightly as they hit the bump or rut, by introducing some compliance between the suspension and the body to absorb the force. The challence with a high-performance sports car is to have some compliance but to prevent it upsetting the crucial wheel geometry. Too much compliance in the rubber bushes will make sterring feel vague and imprecise, exactly the characteristics the designer wants to eliminate. As the NSX's tyre hits a bump or rut, it is inevitable forced backwards, which in turn causes the compliance pivot to rotate outwards. The pivot will not turn more the 10 degrees because, as it rotates, the integral bushes become progressively firmer.

Thus the pivot improves the ride and eliminates steering kickback, but this compliance is not allowed to affect the handling.
When the pivot rotates, both top and bottom whisbones move backwards in unison so there is no change in wheel alignment. In fact, it barely changes over the entire lengthy wheel travel. And this suspension design makes it possible to have very firm bushes, for precise control, in the rearmost wishbone pivots which are subjected to the highest loads during cornering.

Excellent high-speed stability is ensured by eight degrees of castor, and the design also increases the camber angle of the outside wheel in cornering to improve grip.

A large castor angle usually results in steering that weights up markedly during cornering, something that makes for tiring fast driving. This has been avoided by offsetting the top and bottom steering pivots from the centre of the wheel.

 

[Larry Bastanza]

Gerard,


Great info. This explains what the compliance brackets Comptech sells does for a race setup, it eliminates the ability for this compliance pivot to operate as designed.

If you think about it, the steering "kickback" described should be felt by the race track driver, right??

Thanks,
LarryB

 

[michaelw]

Gerald, thanks for that as Larry says that does explain it very well. A typical Honda solution, complex but very clever. I have been on track once with the car and am amzed how flat it feels on a "Standard" setup but how good the ride is. I guess this is one of the main reasons.

I have now taken two pitures of the Complaince joints but can't attach them as they are bigger than 100k and believe it or not I have nothing to reduce their size on my laptop apart from Paint which I can reduce them to a certain size with but not small enough.

Many thanks,


Michael.

 

[Cees-Jan]

Gerard well explained, I didn't know about this.I do know that your cars drive extremely direct without tyring on high speed (265 km/h)

Having read your story I now know why you spend so many time with the allignement personel, they are used to standard family cars and not the high tech ..... which we are talking about here(designed 15 years ago.......!)

 

[michaelw]

Hi guys,

I have now managed to reduce the pictures so here goes - one last try:

If you look at the mushroom shaped casting in the centre of picture below (left hand side of the car) you will see that this casting is closer to the casting below it compared to the right hand side (next posting).

This will mean that as the mushroom shaped casting is attached to the car and the casting below it is attached to the wishbones and it appears that you can adjust their relative positions. This will mean in turn that the leading edges of the wishbones are higher on the left hand side than the right hence my concern.

Many thanks in advance again and I promise to shut up about this from now on.

Many thanks,


Michael.

 

[michaelw]

And here is the right hand side:

Many thanks,


Michael.

 

[michaelw]

Just had the car alignment done and there is not enough movement on the left hand side to get the required 8 degrees , the adjustment only allows a maximum of 5 degrees on full movement.

Any ideas what might cause this apart from something being bent? Nothing looks bent to me although I suppose it would not take much. I don't think the above problem (in the photos) could do this but am open to suggestions.

Many thanks,


Michael.

P.S. I know I said I would shut up but this has got me even more confused and would explain why the caster was so far out.

 

[Cees-Jan]

I am not sure but most of the time it is possible to "pull" the lower wishbone forward by loosening the frame bolts and sliding the whole thing forward,or by loosening the front cross bar and slide it forward.It is possible that it slided backwards when taking a bump (especially when hard braking)

 

[V12NSX]

Did the alignment shop actually know how to properly adjust the caster? Most places really do not. They simply adjust camber and toe and hope the caster works out. Or they try to adjust caster without loosening BOTH nuts that hold the cam in place. If they did this properly, then certainly something is either bent or out of place.

S.L.

 

[michaelw]

Thanks guys. Yes the allignment shop did know what to adjust as they do all the alignment for the local NSX dealer. Thanks for the tip on sliding the frame forwards I will have a look at that.

Presumably it moves the bottom of the compliance joint but not the top so that would make a lot of sense.

Michael.