Lost the nut off the back of my countershaft

[RoyBatty]

I was running down the road going thru the gears and heard a noise like something hitting the bottom of the car.
A few miles later the 5 speed started making squealing noise as I went thru the gears and I noticed when I stopped that there was gear oil all over the place.
I had to get to work, so I nursed it the last 8 miles to our shop.
Inspection shows that the bearing at the rear case for the counter shaft is trapped between the cross member and the rear of the trans.
I already had a replacement trans on the way from Maryland aand planned to overhaul the one in the car.
Soo, how screwed am I on this trans?

[RoyBatty]

OK then, no help here as of yet.
Here's what I've found thru my own research.
The nut that came off the rear of my 5 speeds countershaft is also the same part used on the axle to retain the hub in the left side of a 124.
It was available from C.Obert& Co. for under five bucks.
The same part number nut is also used on Ferraris and costs as lot more under that brand name!
The part # I found is 14044171.

[ventura ace]

Roy,
I had the same thing happen to me years ago. My tranny started to leak a small amount of oil out the big 3" cap on the tail end of the gear case extension, but I didn't know what caused it. I thought it might have been the cap knocking against the rear tranny mount, so I shimmed the tranny mount with a couple thicknesses of washers, and put JB Weld on the cap to stop the leak (drained the oil out first, and flushed the case out with alcohol, then used wicking loctite to try to seal the cap, and JB Weld for backup). I drove it that way for a few years. Eventually, I pulled the tranny to replace all the bearings, and noticed then that the countershaft nut on the tail end had backed off just like you described. The gear stack up could only move a small amount before it started to rub on a shoulder on the inside of the case, so it didn't result in any undue wear of anything else. The crimp shoulder for the big nut was completely gone due to rubbing on the cap for 10,000 - 20,000 miles!

When you put the new nut on, but sure to torque to spec, then crimp it for secondary retention!

Alvon

[RoyBatty]

Thanks for the reply VA,
So if I read your post right, there is a cap of some type that closes off the hole that the countershaft nut fits in?
See, if that is the case, then mine is missing and I need to find another.
Problem is, I have not seen such a part in the service or parts manuals as of yet.
Tom

[ventura ace]

The cap is part of the rear case. I've never heard of a replacement, so you may have to replace the whole rear case, or improvise some way to close it off. I suggest that you start looking for a rear case from a donor transmission. You should specify the year, in case there may have been a change in design at some point in time.

Alvon

[RoyBatty]

[ventura ace]

Roy,
Come to remember, I may have an extra rear case (for early model transmissions, and maybe for later model, too -- I need to check). I bought a few spare parts from other folks when I had the similar problem way back then. I'll try to do some digging around tonight. Contact me directly when you get a chance:

Alvon Elrod
ventura_ace@juno.com
805-338-1767

[RoyBatty]

Thanks VA,
I'll be in touch.
Might want to move your contact info to a private message?
Tom

[ventura ace]

Thanks VA,
I'll be in touch.
Might want to move your contact info to a private message?
Tom

?????? The private message thing is pretty darned annoying. I prefer you use my direct e-mail or phone to contact me. It's not cloak and dagger here.

I found a tranny rear housing, that I believe may have come from a latter year spider, but don't know for sure. It has a casting number 4326364 inside the housing. Have you been able to get yours apar yet to look inside? Let me know if you are interested in the part, and I'll try to figure out what I paid for it.

Alvon

[RoyBatty]

Hi again VA,
Well I put the car in the air and removed the cross member at the rear of the trans,
This allowed an unobstructed view of the countershaft bore.
I found upon further inspection that a previous "mechanic" had installed the bearing BACKWARDS!.
I was wondering about this and after looking at the cut away in the manual, it was plain to see that even if the nut had stayed on, the outer race was free to work it's way off to the rear.
As for the plug. My rear case seems to have a counterbore in the back of the bearing opening that is made to take a welch plug.
At this time my plan is to install the new nut when it gets here. Install a welch plug to the counterbore, with sealant.
Top up the gear oil. And take her for a test drive.
I'll keep you posted.

[ventura ace]

Roy,
I think your plans will probably work fine, if you can find a plug to fit. I’m not sure if the proper name for it is Welch Plug, or Galley Plug, or Cap, or whatever, but it needs to be a slim design and not protrude past the end of the transmission housing, or else it may bang into the rear tranny mount bracket. I was guessing that the size is about 3”, but in looking at mine last night, I see it is closer to 2.5”. I don’t know the exact size, but I’d think you need to get the correct size in order to get a proper seal.

I also stand corrected that I said the bearing kept the rest of the Reverse / 5th gear from backing out from the countershaft when the nut backed out on my tranny – it was actually the flat side of the gear rubbing against the transmission case that kept it from coming apart any further. I’m not sure why the design is for such a hefty nut for securing the parts together, since it doesn’t seem to have much of an axial load on the parts when installed and operating normally.

I can’t recall exactly, but I’m not sure that it really matters which way the bearing is installed, since there is no axial load (the bearing is free to slide in the bore of the tranny housing). If I remember correctly, the bearing is a two piece design, where there is a piece called the ‘spacer’ that serves as the inner race for one side of the bearing, and the ‘spacer’ is normally installed on the shaft first. However, my guess is that it would work just as well if the whole thing was flipped around such that the rest of the bearing is slipped on the shaft first, and then the ‘spacer’ on the outside. I could be wrong though. It could be that, if installed backwards, the bearing outer race might rub against the Reverse / 5th gear. When I have taken the tranny apart, I’ve always taken plenty of pictures and notes, to assist me in reinstalling parts in the proper order, since I’ve found some discrepancies between the manuals and what I found inside my transmission. I believe there may have been some changes in the design through the years that were not adequately covered in the manuals.
I hope it works out well for you. I’ll keep the tranny rear housing handy in case you have to tear things down further.

Alvon

[RoyBatty]

Your alright VA.
Thanks!

[RoyBatty]

Well, it's working!
YEAH!