Rebuild or replace?

[oddduck]

My '70 needs a tranny in the worst way. It won't go in reverse, pops out of 4th, and leaks oil like a sieve...

It's an IRS, with code AM4657856 (from a random web search: '71 or later tranny with 4.375 final drive). Anyone have any more information on it? Any advice on whether I should try to get this rebuilt with upgrades, or swap for a Rancho ProStreet?  The 1600 is a pretty stock city driver, for now.

Jon

[Bruce]

It won't go in reverse, pops out of 4th,

Have you checked the trans mounts?  What about the shift rod bushing and coupler?

[egspot]

It won't go in reverse, pops out of 4th,

Have you checked the trans mounts?  What about the shift rod bushing and coupler?

Those three can help you a lot.

I have one tranny that you can have for 50.00 (I paid more) I was told it is a 71 super B. As far as I know it works and you could changed it in a couple hours. i also have coupler you can have for free.

[oddduck]

Transmission mounts are intact, although the rubber seems pretty broken down. The coupler has about 3mm of play when I crank on the shifter.  What should I check for with the bushing?  I'm a little embarassed about my lack of knowledge here - I haven't been under a car since high school, and the last "car" I worked on only had two wheels... 

I might take you up on that spare tranny, if this one isn't salvageable. Thanks for the responses.

[egspot]

 your car is a 70, chances are the shift rod bushing and coupler have never been changed . While it is work is is your cheapest solution.

I had a lot of help changing my shift rod bushing and coupler but it is worth it specialy if you may have to changed the tranny at a later date.

While you are at it, if you are dropping the motor to do the change go ahead and change the tranny mount and the motor mounts, clutch...etc.

You would not have to go in there for long while after it is done.

[oddduck]

When it comes out, I'll definitely replace all those goodies.

I'm assuming that checking the mounts/bushing/coupler is to rule out a state where the shift rod simply isn't moving far enough to engage the reverse gear. Is that right? Is there a way that I can test this theory without having to replace all these bits (only to find out that the tranny is probably no good after all)? Could I try nudging the ball housing flange forward to try to force the shift rod slighty further when I shift into reverse, to see if it will then engage? Or will that screw up all the other gears (I need it to go forwards at least a little longer to get the car around)?

Since the mounts don't budge, and there's only a little play in the coupler when I wiggle with the shifter, should I conclude that the transmission is cooked, and get on with the business of pulling out the whole works?

[Bruce]

If the shift rod bushing hasn't been done, it needs it.  It is easy to check.
Remove the shifter.  Reach down and grab the shift rod.  Lift it and move it side to side.  If it has ANY play, it is gone and needs replacement.
If you have 2-3mm of play in the coupler, it needs changing.
It doesn't matter if you eventually end up changing the gearbox, you still MUST do the shift rod bushing.  If you don't, it will accelerate the wear of the new gearbox.

[oddduck]

Un-freakin-believable...

Replaced the trans mounts and shift coupler & made a couple interesting finds: (1) MSD box hooked up to power & ground, but no output, (2) only 3 of 4 engine bolts present, (3) Under heater hoses, fan shroud outlets were blocked off, (4) "OE quality" means the shift coupler will fit neither the shift rod, nor the inner shift lever.

Last, and definitely not least: the previous owner put the shift stop plate in UPSIDE DOWN after putting in the new carpet!!!

[oddduck]

Ok, engine back in, shift stop plate right side up, new tranny mounts and coupler and shift rod bushing.  Still no good.  It shifts nicely into reverse, goes a bit when the clutch is released, but then grinds and lets go.

Back to the original question: does this transmission sound like it's worth having it rebuilt, or would I be better off replacing it for an off-the-counter Rancho unit?

[egspot]

Back to the original question: does this transmission sound like it's worth having it rebuilt, or would I be better off replacing it for an off-the-counter Rancho unit?

That is the choice to make.

The dollar is very much at par but there is shipping..ect.

On the other hand you could get mine for a small fee and have someone here rebuilt yours. If mine works well, you may get time to have the rebuilt late.

Try Bruce or Hans and see if they got time and what it would cost.

[oddduck]

After draining the transmission fluid (and metal shavings), I removed the right CV and another cup of oil spilled out.  That can't be good.  Anybody need an anchor?