4-speed transmission rebuild kit

[loudoun]

I have a 70 build, 71 titled Series 1 car with the original 4-speed manual.  The transmission needs a rebuild and I am looking for a good rebuild kit.  Does anybody have suggestions for a good one?  I would like quality over price, but price is a consideration.  I have no desire to swap out the tranny for a 5-speed.

Before I get flamed, I did search on this topic, but the posts I found were much older and the marketplace could have changed. Thanks in advance.

[Zed Head]

Search EuroDat's work.  He has many posts and at least one good thread on rebuilding.  Maybe even some download material.  The 5 speed references are good for you too, they're the same transmission, just with an extra gear.

Word is that the aftermarket synchros are sketchy.  You need to decide hwo much "rebuild"ing you want to do.  Bearings, bushings, seals, synchros.

How do you know it needs a rebuild?  Many of us have solved synchro problems with better fluid.

[loudoun]

Zed Head,

Thanks for the post.  I know it needs a new clutch, so it will have to come out.  I cannot get it into third or fourth without double clutching. 

[beermanpete]

We use the kit from drivetrain.com. It works fine but the rear bearing for the counter shaft was the wrong size. Maybe it was for the early "A" transmission (we have a "B" transmission).

[Mark Maras]

 Describe your clutch problem. Slipping, not disengaging, noise?

 Double clutching for third and fourth. What about reverse, first and second? 

@KDMatt started a thread called "Found metal at the bottom of my 5 speed. What next?" on May 9th. He successfully repaired his trans using the DIY garage method. It seems intimidating at first but it's very doable. You'll see what you're up against and how to overcome the difficult spots.

 Zed Head is right. These transmissions can be finicky when it comes to oil. Any chance you want to try changing it before you tear it down? It could make a big difference.

[loudoun]

The car will not go into third or fourth without grinding. 

 

[Mark Maras]

 Is that the extent of the symptoms? No problems with any other gears or clutch slippage? Pull the drain plug and see what is clinging to it and what's in the bottom of the case near the hole.  Could be a problem in the 3rd, 4th synchro assembly but it could be a problem with oil. The vary first one I tore one down that had the same symptoms as yours. Long story short, nothing wrong with the internals. Everything looked pristine and the clearances were within specs. Since I already had new parts I installed them. Only learned years later that different oil would probably cured the grinding. BTW, I did take a chance and use the brass synchro rings from that trans in another later with no problems. Never had a chance to prove it but the evidence points to oil.

 

[Zed Head]

37 minutes ago, Mark Maras said:

BTW, I did take a chance and use the brass synchro rings from that trans in another later with no problems. 

You used the synchros on different gears, not the ones they started on?  Many say that the synchros and gear cone wear down together and you can't do that.  But it seems like wear would be similar since they all start in the same tolerance zone.

Aren't 3 and 4 on the same coupling sleeve and shift fork?  Might be part of the problem.

Just to simplify - is the clutch being replaced because of the 3-4 grinding problem or because it has problems anyway?

A relevant anecdotal aside- you can shift a good transmission without the clutch once you get moving.  I drove my old GTO all night that way back when it was too early to go home (high school weekend) and my clutch linkage broke in the early evening.  Started it in first gear, then just matched RPM to keep going.  Timed the traffic lights, etc.  No racing that night though.

[Mark Maras]

11 hours ago, Zed Head said:

You used the synchros on different gears, not the ones they started on?  Many say that the synchros and gear cone wear down together and you can't do that.  But it seems like wear would be similar since they all start in the same tolerance zone.

Aren't 3 and 4 on the same coupling sleeve and shift fork?  Might be part of the problem.

 

 MY used parts looked nearly new. My friends trans had a broken brass ring. Tolerances were within specs. I thought maybe it would be a little touchy shifting it (but better than before) by mixing parts but it was fine. I wouldn't have done it if the parts were worn.

 Yes. Third and fourth are an assembly, shifted with one fork.

[EuroDat]

In my experience, if its oil causing the problem, 1st and 2nd will let you know earlier than 3rd or 4th. Odd that you have trouble with 3rd and 4th. Its generally 2nd and 3rd or 1st and 2nd, but 4th tends to last the longest. Does it select the gears when you are standing sill and clutch disengaged? Could have been rebuild long ago and someone replace 1st and 2nd synchros and now 3rd and 4th are worn out.

The synchros are the same as all the 71 transmissions. You can use the ones in the 71C 1st through to 4th. The bearings are different though.

The Nissan p/n: is 32604-P0100

Bearings are different from the 71B. I have an old SKF catalog that lists the bearings for these transmissions. Ill see what I can find and post it later.

Edited May 26, 2016 by EuroDat

[EuroDat]

I found a list, but the 71A is not listed.

I added the 71A Nissan numbers to my bearing list.

 

Datsun 71 series transmission bearings.pdf

Tranny_Rebuild_FEB2012.pdf

[Zed Head]

On 5/26/2016 at 6:39 PM, loudoun said:

The car will not go into third or fourth without grinding. 

I would take a look inside before buying a rebuild kit.  Sounds more like a broken part, than something a rebuild kit will fix.  Along the same thought direction as EuroD, 2nd and 3rd usually show the signs of wear.  Not 4th, for sure.

If it has high miles it probably needs a new clutch anyway, before you grind the rivets in to the flywheel.