Rear left vibration underbraking

[Hadrien*]

Hello all,

I am one week away from leaving on holiday for a 2500miles roadtrip with my gf and I have a braking vibration.

I am pretty sure it is coming from the rear left, no steering vibration at all but a strong noise and circular vibration behind me.

What i did so far :
- I could have access to new disks so i regrinded them ( made by a pro guy ).
- Changed the pads ( greased them well and pushed the piston in the calliper nicely )

Nothing changed

My exhaust is a bit shitty it is an aftermarket stuff and it touches the rear swaybar ( he has been since i owned the car but there was no vibration before ). I grinded it a bit and now it appears not to be touching anymore.

Nothing changed

I put the car in the air and checked for bad bearing but the make no noise and the wheel is not moving at all.

And then after more test i discover something. The vibration is mostly here when i am breaking at speed above 40mph, and with quite some pressure ( above 40% i would say ).
But it doesn't vibrate AT ALL when i clutch or put in neutral and does the same brake teste. So vibration is only here when i am in gear.

When i turn the wheel in the air it does make quite some noice and i feel some play in the driveshaft ( both side ). Could it be a worn driveshaft ? My car is bang on 100.000miles.

Anybody experienced something similar ?

Thanks for your help guys, fighting to fix this before leaving...

 

[Albert86]

I think the pros are going to ask year of your car and if you have the maintenance history.
If not how long have you owned the car (years and kms),
Do you know the CV joint service history?
Do you see any evidence of CV joint grease escaping the boots?
The grease could be thrown about a bit if they are giving up.
The boots are usually easy to get in US; I don't know about France.
Best wishes making the trip come off.

Adding this:
http://www.nsxcb.co.uk/showthread.php?15719-Drive-Axle-Removal-and-Overhaul

 

[Hadrien*]

Thanks for the answer. Very educative post indeed.

My car is a 1991 NA1, i own the car since 4month about 2000miles the issue appeared to be really minor but it was always here since i own it.

Most recent discovery i made is when i am stoped and de-clutch to move rear-ward with the rear gear engaged, there is a small "clonk" coming for the back of the car.

There is absolutely no leak at the boots of the CV joints and the history of the car on that is :
- The four boots were changed 10 years ago ( 7000miles ago ).
I have part number 46472568000 , 12513PR7A00, 42017SL0000 marked on the Honda receipt.

 

[Albert86]

My car - and I expect most NSXs have some drive train lash - something you notice in the drive train when going from powered to unpowered.
I don't think that in itself is too worrying; I had some but it decreased after a full CV rebuild with all bearings cleaned and re-greased.
I also think the right side may be more prone to CV issues due to being closer to the exhaust.
..
Could it be the two caliper pins are worn on the left rear side?
When you did the pads did you pull the caliper frames apart, inspect the pins and re-grease?
..
When you pull the rear wheels are the big axle nuts tight?
They are swaged (the nut is made to be deformed into the axle key way) - is there any evidence of the swaging not lining up with the key way in the axle?
..
Did you try a search for rear vibration on the forum (sorry I didn't for you).
..
Hoping someone else (better than me) chimes in with the magic reply to isolate your problem.
(PS - I'm still a bit worried about your refinished left rear disk - did you inspect for hairline cracks?)
Also - does this happen all the time or do you have to drive ... 20 km for it to happen, won't tell me anything, but could be a point to someone else.
Hope you sort this out - Al

 

[Hadrien*]

Thanks for you help Al

I didn't inspect the pins and re-grease them when i changed the pads.

The big rear axle nuts are tight yes. I haven't check if the swaging is lining up with the key way in the axle.

I tried to search the forum yes of course spend a few hours already looking at everything.

There is no hairline cracks on the disk, but actually i suspect it is a warp disk, first there is no service bill mentioning they were changed in their lifetime ( front yes ). And actually the vibration occurs after a few brake test or a few km. I do have to drive for it to happen. Which makes me think it gets bad with higher temp.

 

[Albert86]

Sorry I am tapped out for suggestions other than the pins.

You would need a dial indicator to check for warp of the brake discs

I don't know if failing ball joints act like this, only other thing I can think of.
Sorry we didn't straighten it out.

Are you going for the trip anyway?
Maybe you're OK if not too many hill or passes to cross - I expect this will not be the case in Europe, only in Minnesota.
Wish you best.

 

[Hadrien*]

Hi,

I am thinking in the end it might be the disks cause it only happens after a few km and the vibration is the same has before i got them machined but much less stronger ( so the machined did get some warp out but not all...) can't get replacement disks anyway on time and Honda doesn't do them anymore.

I am going to take my DC2 instead...GF is gonna hate it ahaha gonna be 8k rpm in the Alps all day

I will order disks and change them end of the month then taped in here if it was the solution.