I just got my Z back after having it stored for several years. I now notice a thump in the rear end under moderate acceleration. I know the first thing that comes to mind is the insulation, and believe me I have not discounted it as the culprit. However: it seems to be fine, the u-joints in the drive shaft and axles dont have any slack either. Mustache bar bushings seem to have slight wear. My problem is that I think the slack is in the rear end diff. itself. I have never had one go bad, but it seems to have quite a bit a slack. :sick:

Does anyone know how much is normal? Also does anyone know of any website that lists the gear ratio's and what year models had what rear end in them?

Trav

If the car has been stored for several years, I would say most of the reason for the clunking you are hearing is because of the deterioration of the rear suspension bushings. Not only the mustache bar bushings but also front differential mount.

All the rears have some amount of backlash, but the bushings cause it to be more pronounced.

I'd replace the bushings first, then see how it is after that. I think you will notice a big improvement.

3.36's in standard trans models and 3.54's in automatics.

240's and 260's had R-180's

some of the late 260's and 75-76 280 had R-200's

After 77 they jumped back and forth between the R-180 and R-200 for some reason. I think they even had a 3.90 available in one of the later years fo 280zx's. Not sure which years were which and I don't think I've seen a list anywhere that spells it out in detail.

This information is not from me. (i'm to new to know any of this). I found this guys site helpful. Not a ton of information but whats there is good.

Follow the advice givin from the members of this site, but I thought this might be helpful as well.

CLUNKING REAR END

This is the bane of all Zcars, it's almost impossible to completely fix. It can have many causes, but is almost never caused by the internals of the differential, especially if it's an R-200.

The following are all the places the clunking can exist:

. worn out mustache bar bushings (replace with urethane)

. u-joints on the halfshaft ends are loose and worn-out (common, replace them)

. tighten all the mounting bolts/nuts on both ends of the halfshafts

. front differential mount broken (try tightening the 14mm nut in the bottom first)

. driveshaft bolts loose

. ball bearings/grooves in halfshaft body worn (replace halfshaft)

. tighten the two large nuts that hold the differential to the mustache bar

. shocks bad or loose in strut

I personally think most of the time it's caused by the mustache bar bushings. These thin rubber bushings rot and flex and let the bar clunk the floor on acceleration.

My 260z had a rear end clunk on acceleration and braking , on my car the culprit was the diff mtg, its hard to spot the fault until you take it off. the rubber separates from the inner and outer metal shell.

good luck

Roger

I'll assume the worst and change out all the rubber, strap, insulator and bushings. I noticed a post that mentioned a 4.11 rear end. I have a 3.90 out of a 83 ZX. What is this 4.11?

Travis

4:11's could possibly have come from the front diff out of a Nissan 720 4x4 or a 200sx Non turbo if it is an R-180. Not too many cars came form the factory with a 4:11, most likely if you find a 4:11 it is one someone has swapped out the ring and pinion with a Nissan Comp part. Only know of one car here in the US that had an R-200 4:11 from the factory, that being the 200sx Turbo.

Is the 4.11 from the 200sx a direct bolt up to the Z or do you have to modify it? I recall that the 200sx came with either a Turbo or v6. Does it matter which one it came from?

My rear thunks on acceleration or just going from reverse to forward. I don't drive this car roughly either.

I have replaced all the bushings in the car with poly. I have new u-joints. Have taken the half shafts apart and cleaned and re-lubed the splines etc. I have a new differential mount. New shocks/springs. Every thing is new and tight except the differential itself and the strap that goes over the top. I think the Z just clunks. Good luck.