Caster Adjustment Problem

[Bob Holmes]

I am trying to free all the adjusters ready for wheel alignment but cannot get this one to move, I have had penetrating fluid on and around the two rings ( that I presume turn round each other ) for a week now, I think this has been move from manufacture as the witness marks shown from where blue paint had been before the penetrating fluid softened and came off when I wiped the area clean.
I have had cooling spray on the inner area and heat ( as best I can ) on the outer ring, I am now of the mind to take the assembly off the car too better apply heat to the outer ring but thought best to ask if anyone has been here before and can better advise me, any help please would be appreciated.

[Kaz-kzukNA1]

Hi, Bob Holmes.

Please be careful with the heat on aluminium parts.
If you use excessive heat (like the burner), it could permanently change the alloy characteristic and weaken the parts itself.

Oxidation is the problem here and once it’s done, you have little chance of freeing it up as the two metal rings are attached with no gap.

Applying the force won’t work because it will be absorbed by several ball joints and the bush around the compliance pivot.
Removing the ball joint may cause you headache as some of them would be really tight.

Have you checked your existing caster angle at the moment?
Obviously, you won’t get the final figure until you have adjusted other parameters but quite often, they are seized at fairly close figure between the R & L.

Some NSX owners were not that lucky though......

The blue paint is indeed from the factory and quite often, even if it is seized, you can get them fairly close enough between R & L as mentioned above after adjusting the camber and toe.

The important thing is to match the R & L caster as much as possible instead of getting the OEM setting of about 8deg depending on the model.
NSX already has huge caster angle any way so personally, if you can get over 5 – 6deg and identical angle between R & L, you should not notice any differences when entering/exiting the left/right turn.


Before starting the alignment session, please check your SAI.
This will tell whether your front end has some sort of mechanical issue or not.
It can’t be adjusted without replacing the frame/parts and it will change every time when you bounce the car.
Should be about 8deg20 but it will change every time when you touch the car.

Unfortunately, seized caster adjuster is very common on our NSX.
Almost all of the NSX that I took for the alignment service showed this issue.

I was hoping to play with the compliance pivot off the car but unfortunately, the used parts didn’t become available so not done yet.

When I bought my NSX new, I had some noise from the compliance pivot.
It’s like 18 -19 years ago so I can’t remember the exact process and also if I remember correctly, you have to follow the specific sequence on re-assembly but you may have better chance of soaking the penetrating oil from above rather than just spraying it from bottom side by removing the long shaft bolt running through the centre of the compliance pivot (the big bolt at the right side of your photo surrounded by the rubber with star like base) and then remove two horizontal bolts at the side half way up the pivot.

This will allow you to remove the ‘T’ shaped tube just above the caster adjuster ring.
Again, my memory is very old and I may be missing something so please use this info with precaution.

Kaz

[NSXGB]

I was hoping to play with the compliance pivot off the car but unfortunately, the used parts didn’t become available so not done yet.

Kaz

I have a pair for that reason, but never got round to playing with them. Maybe if our paths cross at one of the events this year I can pass them to you for your experiments...

[mjames75]

Mine is a 2004 model and they were seized also regardless of how clean the underside is, (be careful not to round the hole on the adjuster! you cannot buy this part separate from the pivot!)
I basically took everything off, arms etc and removed the whole compliance pivot, i used a 10 tonne press on the pivot, managed to separate it (this was insanely difficult however, as theres not much room for the press to work as it just fits on the edge of the top of the pivot. It came apart, and i greased it up, after i put everything back together, the adjuster now moved everything freely :-), pretty magical to see the wheel moving forwards and backwards!

I only did this as I had a cambelt etc done at Honda, they did the alignment and the Passenger side was out quite a bit, drivers side was factory standard. Honda wanted to charge £2000 for a new pivot and told me it was impossible to unseize! Had to prove them wrong, took it back and got alignment spot on!

Hope my description makes some sort of sense...

Cheers,

Mike

[Bob Holmes]

Thanks Kaz and Mike for you replies, before I started this work I recorded the caster toe and camber reading once the new tyres had been fitted.
The rear off side toe adjustment arrows did not line up with each other, the near side caster has been changed from factory settings, three of the four old tyres had very uneven wear, toe and camber values for each wheel were a long way from factory settings and one side did not match the other in any way shape or form, only the caster on both sides was correct.
With new tyres all round, good time to sort this car, ride height in spec, car sat on four turning plates all levelled with each other, half tank of fuel, only missing 75kg from the drivers seat, I have now corrected the toe and camber back to factory settings and now the near side caster is out of specification, guess this is why it was moved in the first place, as the workshop manual gives the order each setting is done in, is this why the caster got moved I ask myself and so now have got the problem of freeing off the caster adjuster to correct this setting.
I will try your suggestions Kaz and if I struggle, move on to Mikes approach, I will let you know how it turns out, meanwhile, any help or suggestions are much appreciated.

[paulc]

Bob, off subject, but whereabouts in Suffolk are you?? I am just north of Norwich.

[Bob Holmes]

Sent PM to paulc