s14 driveline clunk

[hai1206vn]

I want to check with you who have made your subframe bushings stiffer (collar, solid, etc). I had solids on my s14 for a while, then switched to nismo rubber. Well the clunk is still there though not as loud. I've managed to get my shifting perfect 80% of the time, but whenever the shifting is off by only a slight bit I hear this clunk from the rear, and I do feel a tiny jolt/play in the driveline as I usually let the clutch out pretty fast.

Is this normal? My past s13 never had this problem. The clutch on both cars is stock and very strong. The shift shock on the s13 was much smoother and doesn't jerk the driveline as hard. The jolt on the s13 feels more gradual, like it pulls the rpm in place, whereas on the s14 I feel metal parts hitting each other.

The rear end backlash is to spec, diff is s15 hlsd, so it should be fairly quiet. The s13 had all stock bushings & motor mounts in great condition; the s14 has some stiffer rubber & urethane combo. I doubt the bushings affect it that much. Obviously all FR cars have some play there - prop shaft would turn a few degrees before actually driving the rear end. My friend's RX-7 has about the same amount of prop shaft play, but it doesn't shock the driveline like on my car.

I've also tried twisting the u-joints by hand and felt no play (stock shaft). Everything on the car is tight and torqued to spec.

Any idea?

[Def]

What about the diff bushings? The S14 subframe I put in my car had pretty mangled rear diff bushings, which I imagine might clunk a bit on a shift that's a bit off.

[hai1206vn]

All bushings were replaced last year with ES or Nismo rubber.

I've tried listening to videos of race cars, obviously with solid bushings, but they don't clunk.

[Def]

My car will give a slight clunk of the pinion gear engaging the ring gear every now and then, but it's not very loud. It'll rattle if I clutch in while it's under load like decellerating in 1st gear, but again, not what I'd call one of the louder sounds on the car.

[hai1206vn]

you can hear the clunk at 0:02 as I take off http://www.youtube.com/watch?v=ETXY0J_Zyvk

Note: the noise at the 1-2 shift (0:07) is mostly my clutch pedal hitting its stopper

[Def]

I'd call that more a thud from the video than a clunk! Definitely sounds like something is loose or has a ton of play in it. I'd take a pry bar to everything like the subframe mounts and whatnot, maybe the bushing holes are oversized and it's moving?

Oh... and you need a turbo... badly.

[mmdb]

woah that's pretty nutso! Sounds like stress, stress, stress, BAM! I wonder if that's happening when your diff locks and then twists it to cluck. But I really think you needs an v8 LSx to help weed out the problems!

[AdamR]

Tell me your temp guage just isn't working or something.

[Robertftw]

Check engine and transmission mounts as well I had a similar problem once that the trans mount was broken. Also check the center support bearing for the driveshaft as the rubber may be worn in that as well.

[hai1206vn]

I definitely need a turbo!

I'd call that more a thud from the video than a clunk! Definitely sounds like something is loose or has a ton of play in it. I'd take a pry bar to everything like the subframe mounts and whatnot, maybe the bushing holes are oversized and it's moving?

Yes, but the only play i can feel by hand is the prop shaft, which seems normal on all FR cars I've seen.

woah that's pretty nutso! Sounds like stress, stress, stress, BAM! I wonder if that's happening when your diff locks and then twists it to cluck. But I really think you needs an v8 LSx to help weed out the problems!

Diff bushings are all urethane, so it shouldn't twist that bad

Tell me your temp guage just isn't working or something.

Err, all gauges are fine, fuel is low though.

Check engine and transmission mounts as well I had a similar problem once that the trans mount was broken. Also check the center support bearing for the driveshaft as the rubber may be worn in that as well.

Engine mounts are windoweld-filled, tranny mount is Nismo, 1.5 years old, so I'd leave them out too.

The most possible place seems to be the prop shaft itself, either the center bearing or u-joints

[gawdzilla]

Did you install the diff bushings correctly? My most recent install the washer shaped bushing that sits between the subframe and diff was upside down. That results in a small gap between the diff and the subframe. When the diff torques it bangs into the subframe and makes that exact noise.

[hai1206vn]

i looked at the diff bushings. They're facing the correct side, and when jacking the rear up nothing seems to move.

Here's another vid, going real easy on the clutch. This is back when it had solid subframe bushings. Clunking at 0:01, 0:11, 0:38.
http://www.youtube.com/watch?v=xu0Lhk9ypWo

[Matt93SE]

How about engine and tranny mounts? My tranny mount bracket has come loose where the sheet metal mounting tabs are welded to the chassis. It will bend and clunk under shifting torque. I really need to clean the paint off and reweld the thing to the car before it completely tears off.

I also have a lot of driveline clunk in the rear, but I've got ES bushings on the diff and in the Z32 knuckles. heims in the other end of all the arms.. They're getting worn, so there's a little play in all of the joints and I think that causes some of the noise, as well as the play in the ring & pinion, axles, driveshaft, etc etc etc.
one single piece may not be at fault, but you could have enough play in everything added together to cause the noises.

[Rittmeister]

I'd check the driveshaft. I had a similar issue with my S13 when the center bearing got soft. I replaced it with a steel one-piece driveshaft from the DriveShaft Shop, which was a pretty good budget solution.

To check it, I jacked up the back of the car and supported it; started the car, stuck it in first gear, and let the clutch out slowly. With the rear wheels in the air, idle speed is more than enough to turn the wheels. Then get under and look; in my case, I could watch the driveshaft wag back and forth at the center U-joint, since the support bearing wasn't doing its job any more.

[hai1206vn]

I'll go look at the shaft again. This guy has a very similar problem http://www.youtube.com/watch?v=Z3_NVNhC1rE. His video even shows the car shaking so it might be easier for you to recognize the problem. Thanks for the responses so far.