I have searched and read about drive shaft play and clunking in the rear but still no fix.I have ruled out all of the suspension components"Its a drive train issue".I get underneath the car and i can turn the drive shaft about a quoter turn side to side. Its ether in the transmission or the rear end.I read a thread where a guy had the same issue as I but he never found the problem. Any ideas?
Dont tell me to search i have already done so,you smart asses.

 

get under the car and see if the driveshaft has play (up and down) at the diff. the bolt that holds the driveshaft to the dif comes loose and it makes noise.

 

Differential bushings are a major source for clunking. The backlash in the differential of a high mileage car can also cause a lot of slop. When i pulled my stock differential mine was way off, i then set the backlash tighter with the tii differential i put back in. This made a huge difference in play from the driveline. I also imagine the transmission can develop a certain amount of slop.

 

Well its weird to me because i never experienced that drive shaft play when i had my auto transmission on there.It never clunked.Is there away to distinguish whether its coming from the actual rear end? i can also can feel and hear the play on my rear wheels when i move them forward and reverse. when i drive the car the play"clunk sound" is so loud its almost underivable.

 

Check the differential bushings first they make the biggest difference i think. The pillowballs are also a common cause. To check the differential you can pull the drive shaft and rotate the part that that goes inside the differential. You should be able to feel how much play is in there as the pinion gear rocks back and forth between the ring gear. If there is play in there you can pull the differential and reshim the ring gear to set the backlash tighter. On a higher mileage car probably all the parts i mentioned are getting worn, so everything you replace or repair will make a difference.

 

Can you post more information on the backlash and reshiming the ring and pinion. I have never taken a rear end apart so any info would helpfull

 

Its probably better to have a shop do it then. It's not hard, but time consuming and you need dial indicters and the shims to do it. They aren't exactly cheap and usually will take a few tries to get right unless you're lucky. There is a good right up in the second gen section that is very informative, except the backlash is set differently. If you search for my thread where i replaced my differential with one from a t2 it has some information and pics. The fsm also has diagrams. But in all honesty you should either get a shop to do it, or research as much as possible until you have a very good understanding of how it works and what is required.

 

You won't have to mess with the pinion depth or bearing preload. Basically you will removie the differential. Take cap off the pumpkin then check the original backlash just to see how far off it is. Lots of sights have info on this. Then you take the the bearing caps loose which is 2 bolts per side. Pull the differential out of the case. If you reuse the old bearings make sure you keep up with which bearing race goes where.

 

Do you have any links to these threads.I am not afraid of doing this infact this kind of stuff is what i crave to keep me sane.I will buy the tools i need to do this i just need some links or guidence on doing it.

 

Sorry i have been replying from my phone and couldn't finish what i was saying earlier. The easiest way is to measure the old shims and buy new ones that equal the same size as the old shims except slightly smaller and slightly larger, going up and down in size the same amount for each. So if you go a .10" up on one side you go .10" down on the other. The idea is to get the ring gear closer to the pinion gear to take up some of the backlash. It will take a few tries with different shims to get it right. The shims are like 20 to 30 dollars per shim. If the clearance between the bearings is not to spec you may need to go up in size for one of the shims. The fsm has info on checking these specs so download a copy of that if you don't have it.

 

Here are some of the threads I bookmarked when I did mine. The first 2 are related to my differential swap and the 3rd shows the differential bushings i made to replace my worn stock bushings. The last several links are various sites I used to get a good understanding of what i was doing. It took several days of research to make sure I had all the information I needed to get it done right the first time.

1) https://www.rx7club.com/showthread.p...t=differential
2) https://www.rx7club.com/showthread.p...t=differential
3) https://www.rx7club.com/showthread.p...t=differential

https://www.rx7club.com/showthread.p...t=differential
https://www.rx7club.com/showthread.p...highlight=diff
https://www.rx7club.com/1st-generation-specific-1979-1985-18/differential-rebuild-tutorial-711712/
https://www.rx7club.com/1st-gen-archive-71/drivetrain-gsl-se-lsd-teardown-pics-drivetrain-tutorials-coming-soon-717591/
https://www.rx7club.com/showthread.p...ight=diff+swap
https://www.rx7club.com/1st-gen-archive-71/drivetrain-lsd-shot-need-rebuild-kit-581550/
http://www.mazdamotorsports.com/pdfs...Drivetrain.pdf
http://www.gearinstalls.com/97fzj80rear.htm
http://forum.miata.net/vb/attachment...chmentid=28384
http://forum.miata.net/vb/showthread...6&page=2&pp=25
http://forum.miata.net/vb/showthread...7+differential
https://www.rx7club.com/showthread.p...t=differential

 

It won't help to reshim the R&P. The gear wear on an incorrectly set R&P would be ferocious and trash the gears. But in any case, measuring the backlash of the gearing is a good check for gear wear. See the FSM page 40. (I happen to believe that many people who trash their stock diff in fact had heavily worn gears, making the failure only partly due to power handling limitations of the stock diff)

Have you unbolted the driveshaft from the diff to see if the play is in the rear end or the transmission? A quarter turn in the rear end if physically impossible - that's like moving through 2 gear teeth.

Dave

 

well thats where i am confused.When i get under the car and twist the drive shaft backward and forward the diff flange moves with the drive shaft but the wheels or the diff half shafts do not"withing the play". also i never noticed this problem when i had my auto transmission and i just did the swap about 3 weeks ago. so its not like i was racing around and broke something.

 

I'm not saying that something is broken. If you see a lot of play in the differential I'd take it out and inspect it. You can always pay someone $20 to take a couple minutes to check things without tearing it all apart.

 

My differential had a lot of play, was way past factory spec. But the ring and pinion gears were fine. There is more that can wear in there then just the gears that will create slop in the back lash. I used my exact same ring and pinion when i swapped lsd's. I reshimmed the ring gear to the tightest factory spec and it was perfectly fine. It made the whole thing much tighter when driving. My differential tore up the small spider gears, and it wasn't from loose backlash, it was from bumps in a road causeing wheel hop. Wheel hop is what tears them up. If the ring or pinion gear breaks that could be caused from too much slack, but those spider gears are just not designed to take launching abuse especialy if wheel hop is a problem.

 

The automatic trans was probably cushioning the clunking you are hearing. Doing the diff right is a pain and not something I would recommend doing if you have no experience. I have done a bunch of them. It might not even be your diff. Check the diff mount bushings, ppf, motor mounts. When is the last time you drained the diff oil?