Odd 915 problem- hard to downshift into 3rd
 

When I took my '86 apart in 2011 the 915 trans had maybe 10 hours on a full rebuild- bearings, synchros, sliders etc. Everything worked beautifully. Gearbox has sat strapped on my bench ever since, never dropped or shifter shaft damaged. But when I took the car for the very first drive in 8 years today, it's a challenge to downshift into 3rd. Feels like there's a detent holding it back then it'll go in with a clunk you can hear and feel. Upshifts 2nd to 3rd perfectly. All other gears work fine.

Changes made since I'd taken it apart:
Built up a 3.6
Aluminum Patrick conversion flywheel
Still has the original aluminum pressure plate, new clutch disc.
Rebel Racing engine and trans mounts- the ones with poly bushings not solid
Stock factory short shift gone, replaced with Gretener raised tunnel and early JWest shifter
Still run Swepco 201

All the gates are adjusted properly, all other up and downshifts work fine. In fact the 2-3 upshift is like butter. I really don't want to tear the gearbox apart, it took me 8 years to build this car and it's finally running.

If I were you i I would firts check shifter coupler bushings, if the problem persisti i would replace trans oil and also check for metal particles.
I'm quite sure your shifter coupler is out of order.

did you make sure this piece(block)number 4 did not slide out of its position??Did it shift fine before installing it into the car?

Ivan
http://img.pccreation.net/photos/201904221231228827.JPG

Were the dog teeth replaced?

Yes they were. At the time of the rebuild I installed a Wevo pump driven spray bar plus 20:32 second and 28:24 fifth with all new components on those too. So everything was new from 2nd thru 5th. Worked perfectly when I took it out of the car in 2011. Upshifts to 3rd beautifully.

New brass shift coupler bushings installed when I put the engine and trans in the car.

Did you measure it loaded with a synchro? Until a couple years ago all replacement teeth available did not have the proper backcut on them to account for the curvature of the synchro ring. In the upshift the synchro does very little work. It’s the downshift where it earns its keep.

Back to figuring this out again. Been driving the car periodically but still have the problem. Not just the 4-3 downshift but the 3-2 downshift too. I ALWAYS heel and toe on downshifts, have for 30 years, but this doesn't help either.

To clarify, this 915 had been rebuilt in 2010 and worked beautifully for probably 20 hours of track time when I pulled it out of the car for a total car rebuild. Trans was not torn down at all, it worked perfectly when removed from the car

What was changed:
3.6 installed along with the aluminum Patrick flywheel that Steve Timmons supplies with his conversion hardware.
Stomski shift coupler installed.
Gretener raised tunnel installed.
JWest shifter replaced the Wevo so I could try different height shifter handles. This is a very early JWest that uses a 2-bolt battern which perfectly matches Hurst shifter handles. I'm running a 6" tall handle.
Wevo trans cooler hardware installed. As part of this work, the lower shift fork cover was replaced with the machined Wevo part. Haven't pulled it off yet to make sure the fork is bolted to the studs tightly.

So now I'm backtracking to see what possible items I can eliminate. Gonna borrow my Wevo back from my BIL. Going to pull the lower cover off and move the fork to the factory cover. Something changed and I don't know what at this point

Clutch disk dragging or clutch not completely releasing?

Clutch releases properly, but thanks for the thought