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Unread 03-25-2021, 05:23 PM   #226
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Default Transmission swap

To get ready for the track season, I'm swapping the "better" g28.11 transmission for the "inferior" g28.05. That'll give a 2.75 final drive in place of a 2.2.

I looked into replacing the ring-and-pinion on the g28.11 and tried to order the set. 928 International had one but by the time I pulled the trigger it was gone. Maybe for the best. Replacing that is touchy work and there's the risk I'll just mess it up. I've got 4 (four!) g28.05 trannies so messing one or two up trying to rebuild one seems smarter. Plus, if that works, I'll have the g28.11 for a backup or sale.

So... The Plan was to pick a candidate and rebuild it. Checking them out, they all shifted more-or-less well and all went into 5th gear. That had been the problem: no fifth gear. This happened twice at the track after heating it up good. The Plan includes a gear oil cooler for the transmission.

The best shifting transmission went in and...

Didn't work! It wouldn't go into fifth all the way and the dog teeth just buzzed. I looked at the shift coupler by the tranny and the shifter lever mechanism to no result. I must not have put enough force on it to see the gear wasn't engaged. It looked to be snapping in right, too. "Good that."

The tranny is now coming back out. I'm looking at pulling the drive shaft on the input and seeing if there's a problem or, maybe, a bent fork. The first track day is April 22nd so there's time to work this out.
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Unread 03-25-2021, 05:25 PM   #227
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Default Bent lower arm

With the rear suspension out, I spotted that the right-rear lower arm was bent. Not a lot but pretty clearly. The classic failure is that tow truck drivers strap it down by the arm and bend it. One was one the shelf and a fairly easy swap in.
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Unread 03-25-2021, 05:40 PM   #228
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Default Transmission pull tips

I've done this a half dozen times and am getting pretty good at it. Maybe three hours out and three back in. Everything comes loose now so no hours spent on any frozen, 40 year corroded bolts.

The first trick is to strap the transmission up to the sway bar. A lightweight tie-down strap works well. A few things to do:

Remove the whole rear suspension as a unit.

The rear brakes come off the knuckles and get hung from convenient eyelets provided nearby on the body. Don't disconnect the hydraulics.

The parking brake cable is freed at the lever and pulled out. That remains attached to cradle and the drum brakes.

Mark the position of the toe adjusters. Those can be tough to get off. The nut requires a box-end wrench. An extra-long wrench helps to get the torque. BTW - 19mm is almost exactly 3/4"".

Mark where the cradle is mounted to the body. It may just go back to the right spot but some guidance helps.

Remember to remove the speed sensor and the reverse gear switch. And the clips that hold the wiring to the tranny.

Remove the half-shafts just at the transmission. These are then wired to the cradle to control them. I put plastic bags around the CV joint and tie those up with the wire. That keeps the grease from getting all over and, worse, the joint flopping around and dumping the balls.

After all that, the cradle is held by six bolts plus six nuts on the shock tops. And the 2 bolts to the tranny mounts.

And, remember, there are six bolts holding the transmission to the torque tube. 2 are sort of hidden up top.
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File Type: jpg TrannyStrap.jpg (236.8 KB, 0 views)
File Type: jpg TrannyCradle.jpg (248.9 KB, 2 views)
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Last edited by GlenL; 03-26-2021 at 12:41 PM..
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Unread 03-28-2021, 10:44 AM   #229
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Default

Once the top of the transmission was open, I could see that the problem was not with going into gear. The shifter sleeve was going completely over the dog teeth for fifth gear. The problem was that the shifter sleeve was worn on and slipping on the guide sleeve side. That is, the side of the sleeve that engages the dog teeth of fourth gear when in fourth.

It all looked and worked fine when not loaded. With the output stubs jammed, and in fifth gear, turning the input shaft would make the sleeves slip past each other. "Chunk-chunk-chunk-chunk" At operating speed it sounds like a zipping.

I checked tranny #2 in the same way and it seems OK. I hope that works. Rebuilding a transmission seems in the future.
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