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87 Z31 Manual Non-turbo
I am hoping to get some pointers from the more experienced z31 owners. I've only had mine a year and they don't seem to follow the normal rules of finding what's broken. LOL
For a Few months now, my car has been having a vibration when above 55-60 miles an hour it is highly noticeable. At slower speeds it seems like the bumps in the road. It seems to come from the rear the most. It also is based on speed not gear or RPM and it has a predictable rhythm in that it happens about 4 times a second at about 30. I have a couple of suspects but can't find any proof as far as anything being loose or worn. I have replaced and balanced all my tires, and even went as far a getting a different set of rims to make sure it wasn't the them. I've replaced the rear shocks. When I get under the car (in neutral) I grab the drive shaft and turn it and it has a lot of play before the differential catches; about 2-3 inches/30-45 degrees. I believe it my be the drivers axle going bad or the gearing in the differential. I also checked the DIFF mount and as far as I can tell it seems to be good. It doesn't look worn, just old. It has a couple of surface cracks due to age but they are only about 1/16-1/8 inch deep. I don't have a lot of money and don't want to just start replacing parts until I get it right. I'm also kinda loathe to buy a used axle and the only new ones I can find are from Courtesy Nissan for about $650. Also when I shift from 1st to second there is a clunk from the rear. You feel it more than hear it. I think it comes from the extra play in the diff. I really think my problem is coming from the differential, but again want to get a few opinions before I invest in another one. I found one at a local junk yard. I didn't look at it much so I don't know it's condition. I was there for a hood.
That's all the info that I can think of for now. If anyone has any idea on what else it could be or how to check it better, please let me know. And thanks ahead of time.Typical Red 1987 Z31 Jan.87.
In process of NA2T Conversion
87 NA Build -
Bad diff mounts often don't look bad while looking at them not under stress. I have pulled two of them that were "clunking" badly and replaced them with a poly mounts which took the "clunk" away. The bad mounts had no visual clues that they were bad when removed.
Subframe crossmember bushings are the next thing you should replace.
These are not things that you would be wasting money on by replacing. They will make a difference and are most often the cause of the "clunk".
Having said that, it could be something else and there are a few members here (Careless) who have replaced almost everything trying to find the "clunk" and still have not found it.
Some other things to look at.
Driveline/u-joints
CV axle
top shock mounts
rear wheel bearings
differential carrier/pinion bearings
bent wheel/bad tire
1988 300ZX Turbo, Shiro Special #760
1988 300ZX Turbo Automatic (wife's car)
1991 Hard-body 2WD
http://zccw.org/zccw/?page_id=1215 -
Thanks for the reply. I really want to knock out that vibration/shimmy before the clunk so it doesn't cause more damage as I drive. I planned on replacing the rear crossmember bushings, and Diff mount with the poly ones next anyway. I checked the U-joints and didn't see anything loose. I suspect the left CV axle but It's hard to tell with it being on the rear end. I've only checked FWD ones. I'll go ahead and change the top shock mounts when I drop the rear to do the poly's. and I know it's not a bad tire. I've put eight different tires on the car with absolutely no change. When I drop everything I'll go ahead and replace all the bearings, too. This should fix it. I hope. If it don't I'll start changing CV shafts and then the Differential Internals. (Hoping not to have to do this.) As soon as I can get the shimmy and clunk repaired the car is going up for sale or getting traded in on a newer model Z.Typical Red 1987 Z31 Jan.87.
In process of NA2T Conversion
87 NA Build -
How did this work out for you and what cost? at a shop?
I have a full poly kit and already did the rear shocks but I definitely have slope in the drive train and axle. It doesn't effect driving but I do notice from dead stop the clunk when it loads up is probably from the slip in the joints etc. Then I also notice a mechanical whine when I go in reverse that comes from the rear passenger said same side the axle appears loose or worn. I take it that is the boots and grime/dirt and I need to replace. -
when you have the shimmy, and you put the car in neutral while driving does it go away?east0352 wrote: Thanks for the reply. I really want to knock out that vibration/shimmy before the clunk so it doesn't cause more damage as I drive. I planned on replacing the rear crossmember bushings, and Diff mount with the poly ones next anyway. I checked the U-joints and didn't see anything loose. I suspect the left CV axle but It's hard to tell with it being on the rear end. I've only checked FWD ones. I'll go ahead and change the top shock mounts when I drop the rear to do the poly's. and I know it's not a bad tire. I've put eight different tires on the car with absolutely no change. When I drop everything I'll go ahead and replace all the bearings, too. This should fix it. I hope. If it don't I'll start changing CV shafts and then the Differential Internals. (Hoping not to have to do this.) As soon as I can get the shimmy and clunk repaired the car is going up for sale or getting traded in on a newer model Z.
And dont assume the U joints are ok, take off the driveshaft and physically move it and turn it to see if its free and to see if there is play. That was my mistake.My Build Thread -
It's been a while, so far I've managed to get rid of most of the clunk. The right side sub-frame bushing was bad. I've replaced all the bushings with the poly bushings with the exception of the rear diff mount, trans mount and engine mount. I just don't have the money for the diff mount but it's coming up as it broke almost as soon as I put the new ones in. I'm still getting the vibrations, but I'm pretty possitive I've narrowed it down to the left side CV. I'm still getting a little clunk when I shift hard but the differential itself has too much slop in it and needs to be reworked. I can put the e-brake on and still turn the input about 30-45 degrees before it stops. That's way too much. 10 degrees is about the most you should see. I also have a warped rotor on the right side and it may be contributing to the vibrations, too.
I've checked it all when in neutral, I've even lifted the car and put it in gear to see where it's coming from, and still couldn't see anything. I just moved to Germany and took the car with me, I won't be selling it anytime soon, and was fortunate enough to find a 87 sitting in the on-base salvage yard. I got the whole rear, from the sub-frame back for $70, and it's going up as soon as I replace all the seals and swap out the bushing from the old rear-end. While I'm at it, I've removed the toe adjustment bolts and alignment guide brackets from the new sub-frame and I'm installing them on the outer control arm brackets. I'm going to turn them side-ways and weld them in. Then I'll have the ability to adjust toe and camber when I install my sport springs, next month. I'll get some pic up after I've finished it.Typical Red 1987 Z31 Jan.87.
In process of NA2T Conversion
87 NA Build -
rotors wont cause a vibration at higher speeds
Take out the driveshaft. And make sure it moves freely. Dont just look at it. I can guarantee that you cant even visually look at the yoke on the transmission end....there is no way. That threw me off before. Just take it out and check it.My Build Thread -
Clunk and vibration from rear end? Give up the Taco Bell, and start eating more fibre. -
Ummm, yes they can when braking.862sik wrote: rotors wont cause a vibration at higher speeds
.Hmmm, Whats next?
Full Size Bronco, smashing shit.
84ZXT -
wow. sorta unrelated to your topic… but how much was it to ship the car to germany?east0352 wrote: I just moved to Germany and took the car with me -
[quote]shromy wrote:I didn't see him say while braking. He just said at Higher speeds it shakes.Originally posted by 862sikMy Build Thread -
One thing you can try in the meantime… if you don't mind a stiffer ride, you can fill the stock diff mount with window weld. It'll stiffen everything up and probably rid yourself of the rest of the clunk until you can save up for the poly diff mount.
1988 300zxt. gt35, stance, etc. Wheels: Varrstoen ES2 18x9.5 et-13 225/40. 18x10.5 et0 245/40
1990 jetta vr6'd -
or slide two pieces of 1/4 plate in there with angle cut edges and weld those sum-bitches to the diff mount.
there's a bunch of ways to stiffen that thing up. you can even drill and tap holes diagonally through the center and drive large bolts into it to stiffen it up.
the thing about window weld is that it takes time to cure- especially if it's thick. solid mounting takes no cure time! just dunk it in a bucket of water after you're done if you're a hasty person (prob not the safest way to cool welds). -
you know, you can buy blocks of rubber. You can make a temporary rubber mount with as little as a couple of studs, nuts for the studs, a block of rubber, a drill and a saw.Toyota Corolla Ae86 Levin
Nissan Laurel C32 [X]
Nissan 300ZX Z31
Toyota Starlet Kp62 [X]
Originally posted by marcopolo -
Okay, I absolutely know the rear right rotor is warped. The front end was warped and would cause the front to wobble, that's the only reason I mention it. Or at least it made the ball joint that wasn't quite out to wobble like it was completely out. I figured out that it was bad about 3 months after the brake job on the front end.
I got a perfectly good diff. mount on the spare I'm working on. It's going up until I have the money for a poly. I'm not going to do a solid mount, It's a daily driver and I don't want to hear the noise. It's bad enough that the noise got worse with the poly sub-frame mounts. The spare rear end also has some CV's that look to be almost new. The diff is much tighter than mine and doesn't have the 30 degrees of slop when you rotate the input shaft while the e-brake is engaged. That just seems excessive. The spare has almost 0 degrees of slop. The rear left hub bearings may be going out, too. The noise increase seems to be a bad bearing whine, and is coming from that side. Also the CV's groan and click when going from reverse to forward. I put on the E-brake and let off like I was going to drive away and the groaning and clicking is obvious. That's making me think it's the CV. I also have a brand new set of rotors and pads that are going in with the new spare.
The only reason the new spare rear end (sub-frame, control-arms, hubs, diff, CVs) haven't gone in, yet, is because I am trying to save the money for the adjustable strut mounts and lowering springs. I'm probably going to go ahead and get it in this week-end, though.
I'm looking into the Eibach springs and the strut mounts that Jason has for sale at Acadiana Sports Orphanage. If anyone knows of better and cheaper ones then please let me know.Typical Red 1987 Z31 Jan.87.
In process of NA2T Conversion
87 NA Build
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