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TR4/4A TR4A Transmission swap.........

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EastBeachNut

Freshman Member
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Lost reverse gear on transmission, have replacement to swap out. Are there any issues I should be aware of? I have also decided to replace the clutch, pressure plate and bearing while I am in there. Any recomendations of what type of fluid will work best here?

Thanx!
 
The cross shaft bolt is a critical piece that must be looked at when the tranny is out for any reason. Put fresh seals in the "new" tranny ,fill with 80 /90. As long as you're covered in grease do the U-joints on the drive shaft too, what the heck.Dont forget the input bushing, and while the flywheel is off look the ring gear over.Good luck!!
MD(mad dog)
 
Hey MD,
Don't you think 90's to high. Would a straight 80 weight be safer because of the brass?
 
Hi,

The oil weight isn't of concern with respect to the brass in the gearbox, just be sure to avoid GL5 gear oils (which are the most common type in auto parts stores). GL5 oil has sulfates in it that will eventually damage brass.

Look for GL4 gear oil in the 80/85/90/95 weight range or just use 20w50 Valvoline or Castrol *racing* motor oil. Racing oil is non-detergent. Regular motor oil has lots of detergents, which you don't want in the gearbox.

Like you, whenever I pull a gearbox I seriously consider replacing the clutch and throwout bearing, rather than having to remove the gearbox again for that job later. It's also a good time to rebuild the clutch master cylinder. If I know the clutch and T.O. bearing are relatively new and seem in good shape, I might reuse them.

This is also a good time to check the flywheel bolts are tight, inspect the ring gear, etc. If clutch work is done, refacing the flywheel and maybe even balancing it might be good ideas. It's also a good opportunity to at least check the security of the bolts in on the drive shaft. Might be a good idea to clean it up, replace u-joints and have the drive shaft balanced.

I agree with MD's suggestion, at least replace the tapered pin that holds the clutch release fork to the shaft... just be sure to get the hardened type to help prevent breakage. It's also easy to install a backup for that pin, a 1/4" grade 8 bolt through the fork and shaft with a nylok nut on it.

Also inspect the two "ears" on the fork, that operate the T.O. bearing. They never get any lubrication, so tend to wear flat spots, but are pretty easily replaceable. A "trick" to keep using one of these even though it's worn is just to turn it 90 degrees in the fork end so that a fresh surface is riding on the T.O. bearing.

While working around the release shaft, check for any play in the shaft bushings at the bellhousing. If there is any, replace them. Be sure to get the early style, 3/4" long ones, not the later 3/8" long that wear out much more quickly.

Also, is the cross shaft the earlier, greasable type with zerks in each end? If not, I'd consider replacing it. An occasional squirt of grease can help those bushings last a long, long time.

Cheers!

Alan
 
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