Need suggestions. Rear end "clunking"

[M13]

Well, I thought this was normal with the LSD in the back, but recently, some friends told me the rear end of the car feels "loose" and "clunky" when I drove them.

The more I thought about it, the more I got worried. DAMN THEM!!!


So, I'm seeing if others had any similar issues, and perhaps have suggestions.

It's tough to explain what the feel is.

Here is what's been done to the car for rear subframe:

Aluminum subframe bushing (works awesome, marginally reduced wheel hop, and more stable)

Other than that, it's all stock. HICAS, stock parts etc.

The feel that I experience:

When I roll from a stop, the car "jerks", and makes a noise like I have a brick in the trunk and is hitting the back of the trunk. Only one "clunk", not a consecutive set of clunking.

My rear end of the car feels tight on turns, I don't think anything is loose. Obviously aside from the fact my stock swaybar is too thin and with stock coils, there is a body roll, but no clunking while turning.

Clunks happen when I change gears roughly. I don't notice this problem too much because I rev match all the time and shift properly, most of the time.

If I were to purposely shift early, or downshift w/o rev matching, the ONE clunking noise happens. It's definately from the rear end of the car.

Also, when I'm stuck in a traffic, the car rolls like I'm braking with a severely warped brake. I'm not applying the brakes, but it has that swinging motion back and forth when going, say 10KPH on 1st gear at 1200-1700. Change to second, feel goes away. Every gear has this feel if I'm rolling slowly. Say 2nd gear, 20-30KPH, 1200-1700 RPM.

I've driven this car for a year and never thought about it much, but recently the suggestion my friends brought up are getting to me.

My history: I've never driven a car with an LSD before this, nor drove other Skylines extensively enough to compare. me if this was an obvious thing that I didn't know, but might as well be safe.

And no, I'm not an idiot for 5spd, I don't stall (engine stalls on its own thx to atmospheric BOV at stops from time to time bleep throttle once to keep it alive) I don't mis-shift, nor drop clutches like a wacko.

Thanks!

[91rsrskyline]

the exact same thing happens with mine too, i was just going to start a thread about it!

over in the gtr forum section, they have a few threads about it. could it possibly be the driveshaft hanger bearing? i heard it might just be differential fluid needs topping up.

[BrianV8]

Yeah same issue here too, i have new royal purple max gear in my diff and the drive shaft bearing felt good when i had the tranny out a couple months back doing a clutch, i think its just loose lash in the diff, nothing to worry i about i don't think.

[M13]

I'm gonna fill up my diff tomorrow and let you know how that goes.

I did my diff at 107XXX KM. Felt amazing, with a matching tranny flush and Royal Purple.

Now the car is at 122XXX KM. Chances are it's low on fluid, (still locks well) but it doesn't hurt to change fluids

I'll keep you updated for those who have similar questions.

[love_boost]

the exact same thing happens with mine too, i was just going to start a thread about it!

over in the gtr forum section, they have a few threads about it. could it possibly be the driveshaft hanger bearing? i heard it might just be differential fluid needs topping up.

with the hanger bearing gone you will feel a vibration also, i would check your pinion shaft/ bearing, i never opened a R32 pumpkin so dont know much about them but your backlash or preload could be off so it the clunk when you shift may be skipping a tooth.

id put money on your pinion shaft bearing

[BrianV8]

yah mine clunks like a son of a gun too. maybe i'll check that out, if that pinion bearing is gone where abouts can you find a replacement or do you have to replace the whole drive shaft?

[kelaog]

I believe you're referencing the U-Joint- This part holds the driveshaft from the frame and has a bearing in the middle. you can replace just the ujoint but you'll need some special puller tool to remove it. You can probably pick up this part relatively cheap but it might be the preload adjustment in the differential.

[BrianV8]

yeah i'm thinking its preload in the diff too because i had the driveshaft out when i did my clutch and it felt fine. Those bearings don't just fail they wear over time.

[Skym]

Clunking from the diffhead is normal at low speeds and is backlash inside the diffhead (cogs moving from coast to coast). Backlash is there to prevent shaft's from getting shocked/damaged. From my experience, if LSD has a problem, it spins one wheel only, I think that's due to shim inside diffhead that has worn out and needs to be replaced with a thicker shim.

If that happens, then sometimes the backlash is excessive and it damages the wheel side of halfshaft's (common problem on driftcars or speedway Midgets which have halfshaft's rebuilt often) and diffside of main propshaft. These shaft's can be rebuilt, balanced by a driveshaft shop, so they are stronger.

This is the shim I'm talking about and link list's the different thicknesses that you can buy from Nissan -

http://datnet.org/TECH-ARTICLE-Tighten-r200-viscous-lsd-t530.html

Some add more shims to lock the LSD, so it acts like a 1.5 or 2way. Doesn't last long if you thrash car and can make diffhead whine. Better to buy a proper LSD from Nismo, etc.

If clunking sound comes from inbetween the front and rear seats during gearchanges, it's the hanger bearing which can be replaced.

If clunk sound is near back of centre console and gearstick moves around too much, rear gearbox mount has failed. Nismo has an upgraded gearbox mount for auto and manual cars.

I think you might be just hearing more NVH (Noise Vibration Harshness) from solid mounting the subframe. Also replace the diffhead bushes with something stronger.

[BrianV8]

thats a really good write up, now he doubles up his shims and he said he used a .8mm shim i believe on top of the existing one. What thickness is our factory shim for he said the go up in .3 mm thicknesses. I would definatly consider doubling up as he has done, get some better locking. Or would it be better to get one thick one to compinsate for both shims.

[love_boost]

id still check the pinion shaft bearing, its realy easy to go under and wiggle the shaft and see how much play there is, it is common that they make a clunking noise when you shift gears at any speed. becuase of it feewheeling then being suddenly engaged puts force on the bearing, and if there is excessive play it will make one clunk, and if you revmatch it probably wouldnt put force on the bearing as much, or at all

[ecokeRB20]

see, i thought i had something wrong with my car, but it turns out the "clunking" for me is because of the oem jack stand. It is held in the left rear fender in the trunk and it moves around in the holder.

[Skym]

It's sometimes the tools for changing tyre, not the jack itself. If you open up the jack, it can stop jack moving around.

[M13]

my trunk is pretty much empty.

Other than a Cusco rear strut bar.


I refilled my diff and it got WAY better. However, I'll lash my diff with a new shim this summer.

[BrianV8]

I think my driveshaft support bearing is on the frits, When i'm going down a hill with no foot on the gas i feel a bit of a vibration in my seet, i touch the gas again even slightly it goes away. What u guys think? bearing? If so is there another car that uses the same one? Or how do i go about getting another? What is the official name of it an autoparts store would understand lol?