FS5W71B 280zx transmisson rebuild

[Dave WM]

more testing. I mesh the gears in the suspect area while in neutral (both housings off). While I hold 3rd in that position I turn the output shaft so the stake in the nut behind 5th gear is exactly at 12 o clock. I reinstall the front bell housing and get the knock at exactly timed to the 12 o clock each revolution. Next to confirm that I can control it I will hold the input shaft still, thereby locking the gears in place at the 12 o clock and shift into neutral and rotate the output to 3 o clock, and then  re engage the sych hub for 3rd. This should keep the suspect teeth engaged but move the knocking to 3 o clock precisely each revolution. If that's the case I have to assume I have found the bad teeth on the correct gear.

[Zed Head]

I'll bet that the gear is cracked and that's why the engagement ring is loose on it.  Maybe the dislocation is enough to affect the needle bearings.  And/or whatever caused the crack also affected the needle bearing cage.  

I'll send that gear out.  I dinked around with it but I couldn't get the gap to open or close.  I'll send the needle bearings out also, just in case.

[Dave WM]

great, should be more fun testing. I was able to precisely set the knock point as predicted above. I tried other gears to make sure and as predicted, the stake nut either gained or lost ground in relation to the knock. Also seems the knock is worst in 3rd least in 4th, perhaps the locked together 4th has some effect on stabilizing the output shaft (input and output locked putting the front case bearing on the output).

Edited November 2, 2017 by Dave WM

[Dave WM]

prelim test with ZH provided 3rd/bearing/ring are looking promising. I did a quick test with the adapter plate in the vice, the knock I heard with the stethoscope was gone. I still have to install the counter shaft bearing and then re install in the housings but maybe this will do it. I sure hope, the only other thing that was suspect was a bent output shaft. I assumed holding it steady will spinning the gears was a valid test, but I may be wrong about that. If this last attempt fails the plan will be to tear down completely and start with a exam of the output shaft using some V blocks and a dial indicator. Thanks again to ZH!!

[Zed Head]

The USPS is pretty fast.  Fedex and UPS seem overpriced now..  

[Dave WM]

14 hours ago, Zed Head said:

The USPS is pretty fast.  Fedex and UPS seem overpriced now..  

that was fast here by Sat 3pm ish

[Dave WM]

I am going out on a limb here and say I may have it fixed. both housing installed (no sealant) still have the front cover off but def no more clunking like before. I will do another video later same as the others with the front cover off for comparison. What I just don't get is I cant see anything wrong with my gear. Now to be fair I did replace everything associated with 3rd gear. I used the bearing/gear/brass from ZH. maybe something in the bearing, can't see any defects on any of the parts. But proof is in the performance. I will button it up completely later. Now the big question, do I go ahead and pop for a BRAND NEW 3rd gear or just run the one from ZH that is working. I maybe able to get a new one for about 100$ delivered, but considering 3rd does not get a lot of use anyway (I would think 4th and 5th would be most used time wise) seems like a lot of money. I also now have to decide which trans to run, the one I have been working on for months now and maybe fixed or the recent JY find. My inclination is to try the rebuilt one, if for no other reason than to prove its fixed in a working environment, keep the other as a backup. It only takes me about 5 hrs to pull and replace, prob faster if I can get the exhaust to unbolt at the cat converter (which I will be doing since the OE muffler has a small hole in it, so will be replaced next time I pull it).

Stay tuned for the what I hope is the final noise video later.

[Dave WM]

I did a side by side comparison of the videos (not yet able to upload) with that I was able to get a better comparison, I think I still have the problem. Did not seem like it was as bad, but the audio from the before and after makes me think something is still not right. Seem like I have two choices, reinstall and take for a test spin OR completely disassemble and check the output shaft for bends. That can be the only thing I can think of. Perhaps since the 3rd gear is the last thing on the output shaft any defect would be amplified. I am sure the noise was less with it on the adapter plate with the new gear (I was listening to the 3rd shift fork selector while slow spinning, could detect a knocking sound), thought I did not hear it at all with the new gear, but the new video you can still pickup on it.

I am thinking of just taking a break from it and letting it stew for a while on what to do next. Again will upload videos as soon as able.

[JSM]

My vote is install and go!  

You don't have any issues with the case itself?  Maybe it is causing binding?

Edited November 5, 2017 by JSM

[Dave WM]

Case seems to go together ok.

[Dave WM]

video with drill test

it sounds ok at 1st but around 1:15 you can hear it knocking again, maybe not as bad as before but still worse than the JY

Edited November 5, 2017 by Dave WM

[Dave WM]

operating on the assumption the problem still exist (same kind of noise with different gear, maybe a bit less but still there), and assuming the only remaining cause can be a shaft issue, the next test will be to affix a dial indicator to the bell housing, and get a reading on the INPUT shaft. while not the shaft I think is the problem I figure if the output shaft is wobbling it will telegraph into the input shaft. The good thing is I have the JY trans that does not make the noise, so I have something to compare to.

Did the test, no significant variation on input shaft run out when in 4th and spinning the output shaft between the noisy and non noisy trans.

 

Edited November 6, 2017 by Dave WM