Output flange of the transmission

[Zedyone_kenobi]

Every since I put in this type B transmission I have and a clunking in reverse that corresponds to speed that I hear every single time I back up and it is by far worse when cold. Never fully goes away though. I was going to do a fluid change just for kicks today. drained the fluid, no signs of a leak anywhere, in fact it was very clean still. Keep in mind this was a rebuild from zcarsource I installed before my rally. IT shifts fine and drives fine. But it has always clunked when in reverse backing up. Clunk, clunk, clunk, clunk when I back up. The fast I back up the faster it clunks. Never had this issue ever with my old Type A transmission that came with the car.

So, It made this clunking with the old OEM diff an the new STI diff.

When I checked the drive shaft ujoints (same drive shaft I have always used) It feels great and solid. NO slack in the joints. But the output flange of the drive shaft that interfaces with the splines of the transmission moves up and down in my hand a bit. You can see it, feel it and hear it. I know the input shaft to the transmission has some movement, no worries there, but I am pretty sure the output shaft is not suppose to move, nor is there suppose to be any slop on the spline interface to my knowledge. When I move it up and down it sounds like the source of my clunk, clunk, clunk (nice onomatopoeia huh?)

So In you guys memory, is this output flange suppose to have any movement?

This is just a dandy excuse to get a 5 speed sooner...

[Mark Maras]

A couple of questions; Has the clunk gotten worse over time? Is there any high speed vibration? Is it difficult to shift into reverse?

I don't recall any movement in mine but it has been close to 40 years since I had one apart.

Mark in Portland

[Zedyone_kenobi]

Great questions.

It does seem to have gotten louder the last time I back it out. I have felt some vibration while driving it that I don't recall. I assumed a tire was giving me grief, but I had them rebalanced and they were fine, but a little under inflated. Still I can feel it in the chassis, but not the wheel. No shifting into reverse or any other gear has never been hard.

[Mark Maras]

The symptoms point to trouble in the trans tail-shaft & possibly the reverse idler gear if the u-joints look good. Since you already want a 5-speed this would be an excellant time for one. Otherwise you'll be opening up your 4-speed to find the trouble.

Mark in Portland

[Zedyone_kenobi]

Well I contacted the vendor I purchased the transmission from. It is LONG out of warranty, but I wanted to see what he would do with it. He agreed to fix it, at my cost, once I sent it to him. The car transmission is definitely NOT happy moving in reverse. I wonder if I could fix this myself. I have my original 4 speed unit that came with my car. It is a type A transmission with the wonky shifter feel, but it never let me down.

I may put that one back in, and try to repair this one. That way I have two spares while I am looking for a proper 5 speed. Datsun parts LLC has a 5 speed right now but I have read reviews from other people here and it scares the crap out of me. I have already bought one bodged up transmission from one vendor, I do not need another.

any anybody tell me if they have had any GOOD experience with Datsun parts LLC.

Perhaps I should start another thread.

[Pop's Z]

Or you could hunt through the junk yards for a ZX 5 spd. We have found that they are around if you hunt for them. The ones we have found are actually in pretty good shape requiring only new seals. Just a thought. I like the 240SX idea also...they are fairly easy to find and require only seals and a bit of machining to adapt the Z bell housing.

Cheers, Mike

[Zedyone_kenobi]

THe 240SX idea just sounds like more than I want to tackle right now. Perhap though after I get my OEM one back in, I will look and give it a whirl.

[EuroDat]

THe 240SX idea just sounds like more than I want to tackle right now. Perhap though after I get my OEM one back in, I will look and give it a whirl.

After doing the STI diff swap, the 240SX tranny swap should be a sinch;) You will need the 71B front section, so going back to the 71A while you build the 71C is a good start. Keeps you mobile.

Im not sure I understand what you mean by flange on the transmission. Does it have a flange like the diff?

It shouldn't. They (71B) normally have a splined yoke that sides inside the transmission. If its flanged, like the roadster 5sp, then the splined section must be an integral part of the driveshaft.

If you can feel any movement, specially if its clunking when you move it up and down, its not good.

The movement in the input shaft, which is caused by the clearances in C3 bearings over a long distance, is removed by the spigot bearing in the back of the crankshaft. The driveshaft yoke does the same thing for the output shaft. The outside of the yoke slides into a white metal sleeve and its probably worn. The 5sp 71B has a replacable sleeve still available through Nissan, but the older 71B doesn't have the same sleeve as far as I know. Not having seen the inside of a 4sp 71B extension housing, it could be machined out of the housing. Maybe other members could confirm that.

Chas

[Zedyone_kenobi]

Wow, that is a lot to digest, but it made sense, thanks for the education sir.

This will be my first trip into manual transmissoin land. I have always treated transmissions like total replaceable units, so I am kind of looking forward to messing with one.

What I meant by calling it a transmission output flange is the input flange from the drive shaft into the rear of the transmission. I can move that up and down.

Edited March 10, 2014 by Zedyone_kenobi

[hr369]

what condition is the transmission mount in?

[Mark Maras]

If I'm imagining this right, the front driveshaft yoke is loose in the tailshaft housing of the tranny? Have you pulled the driveshaft yet and looked at the yoke to see if the outside is worn. Also was the tranny ever run low on oil causing a lack of lubrication? Regardless, It's time for your 5 speed and probably a front yoke. The only thing I found tricky about the 4 speeds is the shifter check balls. A good manual will get you past that point. The rest is easy. Mark in Portland

[EuroDat]

What Mark is suggesting is probably right. The transmission doesn't seem to be in all that good condition. You probably have a badly worn extention house sleeve and maybe some wear on the yoke which is giving you that excessive vertical movement.

The transmission could have run low on oil in its past life or it has a lot of miles on it. Either way it doesnt't sound like a good candidate for rebuilding.

Chas