Front Diff Tech 101-401
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Pale Horse
New member
Re: Front Diff Tech 101-401
I'm being a necromancer here. Before you crucify me, don't worry; I only have information to add. I know these forums are organized and the most up-to-date, easy to access information is obviously paramount for owners and enthusiasts alike.
I present a quandary here. Many of you are like me and break things regularly and becoming a junkyard dog comes with that territory. To that end, there is an odd-ball that I have encountered, and honestly I've changed half a dozen or more of these diffs in my old Syclone or S10/S10-platform vehicles; both 1st and 2nd generation and have only ran into this once.
I pulled a cast iron front differential from an old ZR2 pickup I had purchased for parts a few years back. The previous owner told me he did the Bravada shaft upgrade, and I did indeed verify that it was done and he even gave me the 4x4 tube to go along with it as further proof, not that I really cared. I just shelved the unit and eventually ran low on funds so I sold it. The buyer ended up parting out a couple years later so I ended up with the same front diff again. I installed it into my 2nd gen Syclone that I am building out of my 1999 S-10 4x4. However, I decided to do a full rebuild and I ran into an issue. The part numbers on here for the front axle seals are 100% correct...with one small caveat; I would say 100% correct, 99% of the time. Reason being is that I found this GM oddity. Check it out.
Comparison of typical Syty right-hand axle tube to the odd-ball installed on the cast iron front differential. Also found on the Bravada (I believe that's where this one is from, off my personal 4x4's front diff).
Measurement of typical Syty right-hand axle tube:
Measurement off strange right-hand axle tube:
As you can see these two are no where near compatible. The ID of the seals (the pic was after removing the seal) is identical and works 100% to seal any Syty/Bravada right-hand axle shaft; however, the ODs are drastically different.
I never ended up being able to successfully locate a seal for this tube so I ended up swapping tubes. Just wanted to present it here should someone else happen to run into the same issue.
EDIT: I forgot to mention that this tube uses different bearing sets as well. They are much larger and more robust. Typical bearings for these tubes are only about 5/8" wide; the bearings inside this tube are a good 1.25". I was going to yank the bearings and get a part number but after messing with the seal business, I just wanted to get the diff back in the truck so I just used new typical Syty tube bearings. I imagine the larger bearing surface would provide a bit more protection against the small amount of sideloading that occurs in the inner axle shaft. Not a big deal but for future reference I may go ahead and do that.
I'm being a necromancer here. Before you crucify me, don't worry; I only have information to add. I know these forums are organized and the most up-to-date, easy to access information is obviously paramount for owners and enthusiasts alike.
I present a quandary here. Many of you are like me and break things regularly and becoming a junkyard dog comes with that territory. To that end, there is an odd-ball that I have encountered, and honestly I've changed half a dozen or more of these diffs in my old Syclone or S10/S10-platform vehicles; both 1st and 2nd generation and have only ran into this once.
I pulled a cast iron front differential from an old ZR2 pickup I had purchased for parts a few years back. The previous owner told me he did the Bravada shaft upgrade, and I did indeed verify that it was done and he even gave me the 4x4 tube to go along with it as further proof, not that I really cared. I just shelved the unit and eventually ran low on funds so I sold it. The buyer ended up parting out a couple years later so I ended up with the same front diff again. I installed it into my 2nd gen Syclone that I am building out of my 1999 S-10 4x4. However, I decided to do a full rebuild and I ran into an issue. The part numbers on here for the front axle seals are 100% correct...with one small caveat; I would say 100% correct, 99% of the time. Reason being is that I found this GM oddity. Check it out.
Comparison of typical Syty right-hand axle tube to the odd-ball installed on the cast iron front differential. Also found on the Bravada (I believe that's where this one is from, off my personal 4x4's front diff).
Measurement of typical Syty right-hand axle tube:
Measurement off strange right-hand axle tube:
As you can see these two are no where near compatible. The ID of the seals (the pic was after removing the seal) is identical and works 100% to seal any Syty/Bravada right-hand axle shaft; however, the ODs are drastically different.
I never ended up being able to successfully locate a seal for this tube so I ended up swapping tubes. Just wanted to present it here should someone else happen to run into the same issue.
EDIT: I forgot to mention that this tube uses different bearing sets as well. They are much larger and more robust. Typical bearings for these tubes are only about 5/8" wide; the bearings inside this tube are a good 1.25". I was going to yank the bearings and get a part number but after messing with the seal business, I just wanted to get the diff back in the truck so I just used new typical Syty tube bearings. I imagine the larger bearing surface would provide a bit more protection against the small amount of sideloading that occurs in the inner axle shaft. Not a big deal but for future reference I may go ahead and do that.
Last edited:
Pale Horse
New member
Re: Front Diff Tech 101-401
I'm assuming the seal was Chinese or otherwise non-American. There were no numbers for sure, I searched it all over after coming up short of locating it without part number interchange. I did take the measurements to Advance Auto but they were about as useful as a candle in sunlight. New tube/seal is on and in the truck already. No longer an issue, just wanted to post it here for you guys.
I'm assuming the seal was Chinese or otherwise non-American. There were no numbers for sure, I searched it all over after coming up short of locating it without part number interchange. I did take the measurements to Advance Auto but they were about as useful as a candle in sunlight. New tube/seal is on and in the truck already. No longer an issue, just wanted to post it here for you guys.
Don W.
Stab it and steer it
Re: Front Diff Tech 101-401
No prob. I understand completely. Notice the word "good" parts house. And for future reference often times a hydraulic shop can help. I've done the find-one-that-fits thing in the past. I cheat, I know where to go...:rotf: Interesting find though.
No prob. I understand completely. Notice the word "good" parts house. And for future reference often times a hydraulic shop can help. I've done the find-one-that-fits thing in the past. I cheat, I know where to go...:rotf: Interesting find though.
atomicmecha
I hate rust
Re: Front Diff Tech 101-401
in the up coming weeks i am going to be putting one of these together. I pulled the front assembly from a 94 bravada but it has the 3.73 gears. I have a spare set of 3.42 gears out of an 91 s10 pickup that I'm going to install. I'll take pictures and make a video of it as i go. Hopefully will make a good write up.
in the up coming weeks i am going to be putting one of these together. I pulled the front assembly from a 94 bravada but it has the 3.73 gears. I have a spare set of 3.42 gears out of an 91 s10 pickup that I'm going to install. I'll take pictures and make a video of it as i go. Hopefully will make a good write up.
TWINTURBOV8
New member
So on the zr2 s10 (1995) the front case's will bolt to are trucks?