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Opeler
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Discussion Starter #1
I'm attempting to rebuild the rear end in my GT.
It had a lot of slop and whine in it. While I have a "spare" rear end, i also happen to have squirreled away an Isuzu Impluse rear end.
The Isuzu 3.90 gear set should work great with the 5 spd.

Unfortunately, the rear end had some water in it... Enough to cause the bearings to rust a bit.

I ordered new bearings and races from Rock Auto... They are clearly the wrong ones.
It turns out they list the same bearings for both the turbo and non-turbo models. These were very different animals.

Does anyone know the actual correct bearings to use with the Isuzu pinion in a GT housing?

Thanks
Chris

The picture is of the wrong bearings! Don't buy these!
 

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I would put money on it that its the turbo set. I researched this awhile ago in one RB's old posts. Exact same set I'm running. You are going to want ALL the brake components, hardware, backing plates and e-brake cables from that same assy.
 

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Opeler
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96 Posts
Discussion Starter #3
agreed, they‘re likely for the turbo model. I have all the rear disc brake hardware too. Unfortunately, it’s getting hard to find parts for the brakes too. I haven’t seen a source for the parking brake shoes that fit inside the rotor.

Of course, even though my car is a ‘73, the axle is an early c-clip version. This complicates rear disc brakes...

First thing first, pinion bearings 🤔
 

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Senior Contributor
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Yes, I did a thread on the whole swap including the 3:90 gears and a gripper limited slip diff. I did new axle bearings which are also getting hard to find but I don't think I did the pinion bearing bearing.
 

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Yes, I did a thread on the whole swap including the 3:90 gears and a gripper limited slip diff. I did new axle bearings which are also getting hard to find but I don't think I did the pinion bearing bearing.
Must be under screen name Markandson huh? I cant find it.
 

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Opeler
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96 Posts
Discussion Starter #7
I'm checking in with WorldOEMparts to see if they can order them but they want a VIN :(
I don't have a VIN and the car I scrapped parts from is long gone...
 

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Opeler
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96 Posts
Discussion Starter #9
You know, i may have misunderstood the interchange details between Isuzu and Opel.
I thought i would need Isuzu pinion bearings with the Isuzu pinion. Reading more carefully, i might just need the Isuzu crush sleeve.

Finding Opel pinion bearings is much easier than finding Isuzu pinion bearings :)
Expensive but possible!

Chris
 

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Please post the bibliography of what you are reading. I have yet to assemble mine. I was under the impression that the Isuzu pinion nut was all that was required?? Maybe RB will weigh in on this...
 

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Opeler
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96 Posts
Discussion Starter #11
This has been the most concise statement i've seen on Isuzu ring and pinion swaps:

That said, i'm in the middle of attempting it myself.
I can confirm, the Opel pinion bearings and the Isuzu pinion bearings are identical in size.
I had pretty good used Opel pinion bearings that I pressed onto the Isuzu pinion last night. I've installed the Isuzu pinion into the Opel housing.
Everything went well. I used all of the Opel parts except the crush sleeve (and pinion, of course)!

As pointed out in the thread, the crush sleeve is a very different animal between Opel and Isuzu.
A picture is worth a thousand words:
426583


As you can see, the pinions are almost identical except for a small section in the center between the inner and outer bearings. Hence, the need for the Isuzu crush sleeve.
Opel has a nice little step in the shaft that the crush sleeve pushes against, the Isuzu rides against the inner bearing.

Hope that helps! I'm trying to take a pictures as I go.
I'm expecting new carrier bearings and a pinion seal in the mail today. That'll be the next step.
I did seat the carrier in with the older pitted bearings and it seemed to work out well.
However, i will have to swap spider gears. My rear end is a earlier C-clip style. The Isuzu spider gears don't have a nice machined surface for the C-clip.

I'll take pictures when i get to that step too. Unfortunately, i appears i have to remove the ring gear to enable removal of the spider gears... What crap!
I've never seen that in a rear end assembly before!
 

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agreed, they‘re likely for the turbo model. I have all the rear disc brake hardware too. Unfortunately, it’s getting hard to find parts for the brakes too. I haven’t seen a source for the parking brake shoes that fit inside the rotor.

Of course, even though my car is a ‘73, the axle is an early c-clip version. This complicates rear disc brakes...

First thing first, pinion bearings 🤔
Still available from Raybestos, less than $20.
Raybestos 782PG Parking Brake Shoe
 

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Opel Rallier since 1977
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Interesting problem. If you put that Isuzu crush sleeve on some sort of round arbor of almost the same ID, and then moderately hammer it around and around it will stretch the sleeve a bit. Then do it on the other end the same way. But that will also tend to increase the diameter too. If you did the hammering only on the large end near where it starts to neck down, then the open ends would not get their diameters increased.

I am trying think of other ways to stretch that thing back out a bit. Maybe get a hole just slightly smaller than the large end OD in a piece of steel and drive it into or partialy through that hole using a wood dowel placed inside and driving on that sloped area
 

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Why is it such a chore to remove the ring gear ? I had to do that to gain access to the clutches when I rebuilt the ZF 006 LSD in my Commodore, and I didn't regard it difficult in any way.
 

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Opeler
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Discussion Starter #15
It’s not that bad, just odd. I’ve mostly worked on larger rear axles for trucks, my frame of reference is just different.
 

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The interchange numbers spec these as "like sizes". I questioned it but was told that they "fit". While it appears that the brake hardware would function, the mounting holes in the shoe itself do not match. I inspected the backing plates thinking there may be multiple holes or alternate locations. There are not, as they are dimpled where the t-pins go through. Even though it's just the parking brake, I wouldn't be comfortable drilling secondary holes in the spine of the shoe. I regret that I have posted bogus information in this thread. My apologies.
 

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You can tell that they are cousins. Interestingly enough, the lining on the used one is thicker than the new one. In theory, there shouldn't ever be any wear to the parking brake unless you leave it on. I wonder how much it would cost to have yours re-lined??
Parking Brake.jpg
 

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Opeler
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96 Posts
Discussion Starter #20
Interesting idea, i had not considered the relining option. One side was "missing" the shoes. I probably removed them at some point. I expect they got stashed away and i just need to dig them up. My biggest issue is finding a late model axle. My early c-clips won't work. For now, i'm planning to just utilize the existing drum brakes until i can find a reasonable ($ and distance) rear axle.
 
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