Over drive removal
Thread Starter
5th Gear
Joined: Feb 2025
Posts: 5
Likes: 1
Over drive removal
Hello everyone.
I'm Adam from Australia and I have a 1986 Z51 that I currently have the transmission removed from to do the clutch and fix some oil leaks, I am having trouble finding any information on the removal process for the overdrive unit from the t-10 transmission section, I am hoping some would know where to find this information or has done it before and could give me a heads up on the correct procedure, thanks in advance for any help that can be offered.
I'm Adam from Australia and I have a 1986 Z51 that I currently have the transmission removed from to do the clutch and fix some oil leaks, I am having trouble finding any information on the removal process for the overdrive unit from the t-10 transmission section, I am hoping some would know where to find this information or has done it before and could give me a heads up on the correct procedure, thanks in advance for any help that can be offered.
Melting Slicks
Joined: May 2014
Posts: 2,894
Likes: 592
From: New Port Richey FL
It's ok to take the OD off the T10 but DO NOT take the Allen Head bolts out of the OD Faceplate once you have the OD on the bench, it's under a lot of spring tension.
Also once the two halves are separated the reverse Idler gear inside the T10 will Be loose inside, will stay in place most of the time but there is also a race/shim with it that tends to walk and get lost inside the transmission. So take stock of it because all those parts need to be lined up to put the OD back on.
The best tool to put the two halves together is an old car rim deep enough to allow the transmission stand on it's nose with the input shaft not touching the floor.
Also once the two halves are separated the reverse Idler gear inside the T10 will Be loose inside, will stay in place most of the time but there is also a race/shim with it that tends to walk and get lost inside the transmission. So take stock of it because all those parts need to be lined up to put the OD back on.
The best tool to put the two halves together is an old car rim deep enough to allow the transmission stand on it's nose with the input shaft not touching the floor.
Pro
Joined: Mar 2024
Posts: 537
Likes: 379
From: Northern California
Yeah this is extremely important to note if you plan on doing work to the OD unit. The face plate is under about 1200lbs of force, which is certainly enough to seriously hurt or even kill someone if they weren't careful. There's a video on Youtube on how to properly rig up the unit if you plan to take it apart, but maybe you aren't even doing that. But be careful.
Thread Starter
5th Gear
Joined: Feb 2025
Posts: 5
Likes: 1
Thanks, I have it supported vertically already on my transmission bench, just can't seem to get the OD to separate from the transmission and don't want to start whacking it with a hammer and breaking the case in any way
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Melting Slicks
Joined: May 2014
Posts: 2,894
Likes: 592
From: New Port Richey FL
If you have all the bolts out including the one hidden above the oil pan (outside of the transmission) they usually separate easily, lifting might be challenge but sliding on a flat surface they usually pop easy.
Instructor
Joined: Jul 2015
Posts: 104
Likes: 20
From: Syracuse NY
I built a platform with 2x4s to stand it upright and lowered the OD onto it with the engine hoist. Worked out pretty good. DO NOT USE A PAPER GASKET TO SEAL THE OD TO THE TRANS!! RTV the **** out of it, or use a gasket but also a bunch of RTV. Learned that the hard way then read that recommendation 400 times on here afterward. I also remember one bolt I had to cut a socket down to be more shallow to get it loose.
