Help; Driveline Problem

[That Ozzy Guy]

As some of you might remeber I snapped a uni-joint a short while ago. Last night I thought I did another one but now I'm not so sure.

Here's what happened;

I was giving the car a bit of a workout for about half an hour and arriving at my destination I put it in reverse to park it. I didn't accelerate really harshly as I was in reverse but I heard the same type of crack like the time the uni-joint broke. Anyway, I had dinner and proceeded to go home expecting the car to seize up any minute so I was driving well below the speed limit and staying out of the way of traffic just in case. Nothing happened until I was close to home when it happened again but this time it was in first gear accelerating up a hill. At this point I started to drive really slowly practically trying to creep it home before the half shaft came off.

I got home safely and today I got under there to have a look but could see nothing wrong. I didn't check the drive shaft joints as I was running out of time so I just thought I'd drive it to see if I can snap it. Gave the car a thrashing in the forward gears and nothing happened.

I thought I'd try reverse and I heard the same crack under heavier than normal load. Repeated it again one more time, happened again and then I gave up.

Initially I thought it was the uni-joints but now I'm not so sure. Wouldn't the shaft have fallen off by now? And why would it make the same noise over and over, it can't be cracking over and over right? The only thing I can think of is the diff mount???

Any thoughts?

Cheers

ps, sorry about the story:cheeky:

[carguyinok]

The way it sounds I would still be looking uni-joint. Yes, They can make a cracking sound over and over without falling apart.

I would get the rear of the car in the air and turn the tires by hand. If its the uni you should feel\hear it.

I am not so sure about the diff. mount. They dont make much noise when they go out (other then a thud) not a cracking.

Hope it helps.

[Gav240z]

I tend to agree when you replaced the uni joints did u do the main drive shaft also or just the half shafts?

These can be a bit noisy when accelerating or reversing initially.

My uni's are stuffed also but I haven't had time to fix them up yet thinking of doing a swap to 300zx Turbo HalfShafts(Z31) i think. I can get it done for around $300 just gotta confirm I can unbolt them and slot the old uni's in no problem as I dont like making mods that I can't undo easily for originality sake.

Apparently it also makes the car alot smoother.:classic:

[justaZcarguy]

I would take the car in to the air and see if you get any side-to-side movement from the shaft. I had a friend that was experiencing the same thing that you are and there was nothing left of the u-joint and it still held. It was noisy but it still held...

Have a great Sunday, gotta go work on the '74...

~Brian

[That Ozzy Guy]

Originally posted by carguyinok

The way it sounds I would still be looking uni-joint. Yes, They can make a cracking sound over and over without falling apart.

That's what I was hoping. Thanks. I wonder what keeps on making that noise though. I thought the crack was the caps or joint breaking off and it'll only happen twice (one for each side) and then the shaft would come loose?

Anyway, it's holding on so I'll just take it in to this driveshaft place on Saturday and see what comes of it. Might try to get some cv's made up.

Cheers guys

[2ManyZs]

Just an off the wall thought here George, but you seem to be saying you here it in reverse more than in a forward gear is that correct?

I'm wondering if it might be wear and/or play in the ring and pinion that is being amplified through the rest of the driveline. Have you taken the rear cover off the diff since you got the car and taken a look to see if the ring gear is showing any signs of gauling in the teeth?

It could also be looseness in the slip joints in either the driveshaft or one of the half shafts as well.

Just a couple other things to take a look at while you are under the car. BTW, I can't remember if you said if this car has an LSD in it or not... could also be that the LSD is causing some of the noise as well..... if it is shimmed tight, it would put a lot of stress on the rest of the driveline and make seemingly insignificant wear make more noise than it would with an open rear..... and conversely if it were shimmed to loosely, it could be locking up and causing the noises through the driveline if it locks up while there is some stress on the driveline such as while turning.

[Alan Pugh]

Hi George,

I too think you should check the ring and pinion but more so the pinion itself. Get underneath the car and try to pull and push the drive pinion into and out of the diff. It probably wouldn't hurt to remove the tailshaft and check the nut that holds the companion flange to the drive pinion, I have seen these come loose before when the haven't been staked when installed.

I'm probably wrong but I think it's worth checking.

Alan.

[That Ozzy Guy]

Keith, it is an LSD and thanks guys. Looks like my weekend just got busier. I'll most likely need help along the way so I'll ask when I (most certainly) get stuck along the way.

Cheers

[carguyinok]

Thanks. I wonder what keeps on making that noise though. I thought the crack was the caps or joint breaking off and it'll only happen twice (one for each side) and then the shaft would come loose?

I have had uni joint that pop and crack for months :stupid: Not that I am saying it a good thing or safe. The sound is the joint falling out of place then being forced back in place :sleepy: Once you hear it replace it. Otherwise once it falls you may find a shaft beating the hell out of everything on that side. Floors a-arms brake lines and so on.

[That Ozzy Guy]

I couldn't find the broken uni and I did take it to a driveshaft mechanic on Saturday but he couldn't help me either. He did say it definately sounds like a uni problem though. I'm not going to bother taking the shafts out to find the broken one as I want to convert it to cv's.

Does anyone know if the Z31 shafts Gav was talking about bolt right in? If not, which ones do?

Cheers

[drunkenmaster]

They dont "bolt right in".

You will need two left Z31 shafts and one right Z31 shaft, or was it two right Z31 shafts and one left? :stupid:

Anyhow you need 3 of them and there is some cutting an welding to get the length right.

http://www.speed-technology.com have done a few in their time.

[Gav240z]

I was told you need to modify the ends so that it will bolt up to the stub axels. I was told you don't have to change the length of them but not 100% sure.