Datsun Roadster Forum-311s.org

I have what I believe is this transmission and 5th gear has gone out. Cruising up the freeway it just disappeared. No noises, vibration or anything.
Is there anyone here with experience or knowledge that may have an idea what happened and what it may take to fix?
Supposedly it had been rebuilt before I got it and was unused at that point if I remember correctly. I have put less than probably 5000 miles on it.

There are two main causes for this failure. Some models have a double nut and lock washer on the output main shaft. If they come loose, you can / will lose 5th gear. They also have a 2 piece 5th gear, with the syncro- section brazed to the main gear. These are known to come apart.

If you search our site, you will find lots of information on this problem.

I would bet its the Nuts came loose because the transmission was just apart and they are difficult to get tighten properly.

If you post your location we may be able to direct you to a shop that is familiar with this trans and can help you out. Unfortunately, it all has to come back out!

Thank you guys for the replys. I have been reading a bit on the situation here. I am in Renton, WA.
Hopefully I can pull it out soon and get it apart to inspect.
If I understand correctly, if the nuts back off, that can render reverse inop and other bad things to happen if driven?
It's not a daily drive so it has been sitting. Although no other issues are present and reverse is working normally.
That leads me to believe the gear has only separated and can possibly be rewelded by a skilled welder? Or the nuts haven't moved much yet?

I checked with Rallye in Graham, WA and he does not have a splined gear.

Chris

Did it pop out of gear from time to time before dropping 5th? If so, odds are its the mainshaft nuts. If it shifted fine, but suddenly went to neutral, its likely a press fit 5th. I've had both failures, the most common was the 5th gear failing. Its happened to me a few times, once was a stock 5th, then a welded 5th, another stock 5th, then in 2012 it was a missing little ball bearing that fits under the mainshaft nuts. It didn't make it into the box and I had issues with the transmission not wanting to go into 5th, then it would randomly pop out of gear. I pulled it apart and sure enough 5th was fine, but the main shaft nuts had walked. (Note, there are two versions of the mainshaft, one designed for a single nut, and one designed for 2 nuts. They need 250 ft lbs of torque to be right.

Will

I can recommend a shop in Puyallup who immediately knew my car and what was in it when I pulled up. They rebuilt my box. Raymond Transmission, 1134 E Main, Puyallup, 253 215-3286. Looks like they have a website. It was comforting to know that the owner was very familiar with the Roadster 5 speed. After she is back together, fill it with Swepco 201 gear oil... huge difference in how cool the box ran. A little more expensive than others, but worth the price as others will atest. Available on line.

Thank you guys.
There were no other issues until 5th dropped out.
After welding the gear and it broke again, is it scrap or can another attempt be made to weld it?
I haven't had many boxes apart but I hope to at least get it apart myself to inspect.
Thank you for the recommendation on the shop. Did they weld your gear or rebuild the box with no other work?
Any recollection on prices for welding or rebuilds?
Thank you again.
Chris

Its very common for off-road VW transmissions to have their gears welded...they use the same type of brazed gear.
Its best to weld and then hone the gear. This is a repair one could do themselves except the double nutting takes some enginuity.

Stitebunny wrote:Thank you guys.
There were no other issues until 5th dropped out.
After welding the gear and it broke again, is it scrap or can another attempt be made to weld it?
I haven't had many boxes apart but I hope to at least get it apart myself to inspect.
Thank you for the recommendation on the shop. Did they weld your gear or rebuild the box with no other work?
Any recollection on prices for welding or rebuilds?
Thank you again.
Chris

It has been a while, but my issue was a bad bearing. I believe my gears had already been welded or otherwise fixed when it was gone through when I lived in So Cal (I think Dave Premo built the box for me at that time?). The bearing failure was unrelated to that rebuild, but the box had become very noisy. Knowing what can happen, I drove it to Raymond's, the owner listened to it and knew what was the likely problem, got it rebuilt, replacing anything that was needed. Good guys as far as my experience.

I suppose a 5th gear could be rewelded after its failed once, but the better solution is running the proper splined 5th.

Will

Major thread dig!
Finally pulled it apart today. Found the double nuts are indeed loose.
Also looks like the 5th gear has come apart maybe? Can’t get the splines back in.
Does the overdrive bearing need a puller to come off or should it easily slide off? (It’s not easily sliding off) snap ring has been removed.

Should I start a new thread for this at this point?

That looks like a splined fifth that came apart. In order to remove it you will have to pull off the bearing and gear on the bottom shaft. Easy to do with a gear puller.

Thank you for confirming. I think I can come up with a puller for the gear on the counter shaft. But probably not the rear bearing on the main shaft. Any tips or tricks for getting that off without the proper puller?
I found there is a company that will take the gear as a core and send a repaired replacement. Should I ask if I can have this one repaired and returned as it is a splined unit and would be preferable than a non splined one that may get sent?

A bearing splitter and heavy duty harmonic bal puller with long bolts usually
Best to get the Syncro hub and sleeve -R&5TH
The syndrome hub ( fucc/=// keeps changing my words syncro__ ...) is tough to get off and on
I'd put the nuts on with out the speed gear to see they do not sieze/ jam before they do and remain perpendiculre

I would definitely want the splined back! It is pressed on the gear and I'm thinkin the reason it slipped off is because the nuts came loose. Does it really need to be welded? I will let others chime in on that. The main shaft bearing in the pic should hammer off pretty easily, not a hard press fit. I would at least replace the 2 in the pic and the furthest one back on main shaft. Like spyder said, with a puller, bearing and gear will come off easily. Don't forget.... there is a ball inside that thick spacer that goes in a hole on the mainshaft behind 5th gear! Good luck