Got clunking when applying / backing off throttle at low speed. New driveshafts?

[pedert]

Hi all,


First, being a newbie to the NSX world with my recently bought '91 manual, I'd just like to take the opportunity to say thanks to this community for providing so much great information and advice. Now, I've googled this and searched the forum here, but can't find any topics close enough to my issue, so I figured I'd post my first post here asking for some tips.


Issue:
Clunking sound coming from the rear of the car (right side) when I'm applying throttle or taking my foot off without clutching.
It is very noticeable under 10 mph. It might be that it happens at higher speeds as well, it's just not audible through all the other normal noises. I decided jack up the car and do a bit of research and film. Check the video here: https://vimeo.com/222695232


Research results:
With right hand side rear tire off the ground, the car in 1st gear and without parking brake applied, I get some play when I try to rotate the wheel by hand. Initially approx. a bit under an inch. Then if apply a bit more force perhaps 1/3 inch of more play - that is also when the clunking sound happens. When filming the driveshaft joint behind the oil pan, I notice there's some upwards play when rotating the wheel.

Question:
What is this? Am I missing some bushings or is it excess play in the splines somewhere? Do I have to get myself a new driveshaft? If so, should I change both sides when I'm at it?

PS: Sorry for the slight oil-drizzle , it's coming from an overtightened oil-pan (I think). I've got a new seal that's going on it.

Any help or tips will be very welcome!

Cheers,
-Peder

 

[8R6]

thats EXACTLY the same sound and symptoms that i have on my car except driver-side rear. no grease leak anywhere, no cracked rubber boots, but very slight play in the axle to make a clunking. definitely hear it in low speed accelerations and only during acceleration and not coasting off throttle.

Been trying to look for oem replacement axles. best option so far seems to be the insaneshafts for $600/pair but im still hoping i can find a set for less since i dont need axles rated for 500hp lol

 

[Old Guy]

The NSX drivetrain has a fair amount of lash in it which can make for a lot of noise in on / off throttle slow traffic. I did the same turn the rear wheel test on my 2000 when I first got it. Turns out no material play in the driveshafts - all the noise was coming from somewhere inside the transmission / differential housing. Your clunk does seem louder compared to what I remember; but, it has been 5 years since I did that test and your camera recording may be accentuating the noise.

When you did your test for play on the right rear, did you by any chance check the left rear? If not, do so. If you have a significant difference in the play / noise between the right and left sides, then you may have an axle wear problem on the right side. If the play is equal, chance are you are dealing with the normal NSX drivetrain lash - or you have equally worn drive shafts on both sides. Because of the play in the transmission, you need to find some way to clamp the outer housing of the inner joint so that it can't move. This would then allow you to assess whether there is significant play in just the driveshaft.

New inner and outer joints are available from Honda. If both ends are damaged it is not that much more expensive to get a completely new driveshaft and save the hassle or rebuilding and repacking the joints. Since the OEM driveshafts are not cheap, you will want to pull and inspect before you arbitrarily replace both sides.

 

[MaxGeek]

I did the same turn the rear wheel test on my 2000 when I first got it. Turns out no material play in the driveshafts - all the noise was coming from somewhere inside the transmission / differential housing.

What did the transaxle noise end up being and how did you solve it?

 

[Old Guy]

What did the transaxle noise end up being and how did you solve it?

I think that particular transaxle noise is a built-in feature of the NSX. Get used to it. If you do a search on Prime with keywords such as drivetrain clunk, banging, lurch, snatch you should come up with lots of hits with the conclusion that most of the described noises are normal.

Developing a smooth clutch style in stop and go traffic can go a long way to minimizing the banging. The NSX has a clutch that for an OEM has a rather narrow engagement point (my opinion) making that smooth style more difficult. Performance clutches seem to have engagement points that get increasingly narrower with torque transfer capability. I have seen some clutches (not on the NSX) that were more like on / off switches. I expect that a performance clutch on the NSX is probably just going to increase the opportunity for that banging in stop and go traffic.