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Discussion Starter #1
Ive seen this mentioned a few times on here, but I really dislike the diffs behavior. When I am going straight, under full power, or dumping the clutch , both tires spin. Turning any kind of corner in the wet or the dry and only 1 tire spins, Its nearly impossible to do a donut on wet or dry roads. I changed out the stock fluid at 18k to royal purple Max gear (85w 140 i think) My 94 Firebird with a clutch and spring type posi was 1000 times better than this pile. Is this the correct function of these types of diff? or is there something wrong, Im still under factory warranty till march so time is coming up soon to get it taken care of. Also a side note, I want to change the gears after warranty expires to 3.91s, I tried a site for difftechnics I had saved but it no longer works, any ideas where I can purchase a new gear set?
 

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Sounds kinda weird. May be a traction control issue. This may be a dumb Q but, you ARE trying what you state with the TC off right?
 

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Ive seen this mentioned a few times on here, but I really dislike the diffs behavior. When I am going straight, under full power, or dumping the clutch , both tires spin. Turning any kind of corner in the wet or the dry and only 1 tire spins, Its nearly impossible to do a donut on wet or dry roads. I changed out the stock fluid at 18k to royal purple Max gear (85w 140 i think) My 94 Firebird with a clutch and spring type posi was 1000 times better than this pile. Is this the correct function of these types of diff? or is there something wrong, Im still under factory warranty till march so time is coming up soon to get it taken care of. Also a side note, I want to change the gears after warranty expires to 3.91s, I tried a site for difftechnics I had saved but it no longer works, any ideas where I can purchase a new gear set?
Our diffs are cone type, and they wear. If you are under warranty, take it to the dealer but expect to have to prove your point. DO NOT mention donuts or powersliding. Instead, tell them when you go through a puddle or when you had to partially get into grass with 1 side of the car, the side in the puddle or mud was turning but the one on dry ground was not.

If you are out warranty, you can try a Difftech diff spring upgrade. This replaces the springs inside with tougher springs and also has larger shims for the spider gears. If you need to know where to get these, PM me as they are not sponsors on here.

If you want to go all out, you can go with a Detroit True Trac or a Kaaz. The Detroit True Trac uses a helical gear design and the Kaaz uses a plate/clutch system. Kaaz (I have one in my car) is for more HP and is about double the price of the Detroit True Trac. Again, PM me if you need a contact.
 

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Also a side note, I want to change the gears after warranty expires to 3.91s, I tried a site for difftechnics I had saved but it no longer works, any ideas where I can purchase a new gear set?
Rocksand Racing. Ask for Frank.
 

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Discussion Starter #8
thanks for the help guys, Im checked out rocksandracing.com they have complete rears all put together for 1600.... way out of my price range. Im just looking for the ring and pinion which I have only found one place so far and they want $800!! crazy! I have bought gears for other rear ends before, more like 300 range. Am I not looking hard enough, or is there only one or two suppliers?
 

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I have to say, I've had no troubles with the LSD function in mine, though I don't make an effort to do power slides or donuts.
 

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thanks for the help guys, Im checked out rocksandracing.com they have complete rears all put together for 1600.... way out of my price range. Im just looking for the ring and pinion which I have only found one place so far and they want $800!! crazy! I have bought gears for other rear ends before, more like 300 range. Am I not looking hard enough, or is there only one or two suppliers?
Talk to Frank, me would probally sell you the rebuild parts if thats all you need. $1600 for an upgraded diff is so cheap compaired to the $4000 plus a dealer wants. Either way, its alot of money.

Our rear is a stand alone made by Dana. With the low production of our cars, there aren't too many choices out there I would assume.
 

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Discussion Starter #11
The info I have been able to find on it so far is that its a Borg Warner unit called an M80 which was then bought out or taken over by Dana, I do not know the Dana model name or number. I think I should trust my instincts and leave the rear alone, I am hoping on keeping this for 10, 20 + years so Im sure It would be better if it were stock to get the resale out of it later on. But man I really wish it was a lot quicker.
 

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That's my intention as well, but things that can be upgraded without visually changing the appearance of the car are going to be replaced. I don't think collectors are going to be too worried about it having headers/exhaust, custom cam, tune, or a CAI... the key is to hang on to the original parts. :)
 

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That's my intention as well, but things that can be upgraded without visually changing the appearance of the car are going to be replaced. I don't think collectors are going to be too worried about it having headers/exhaust, custom cam, tune, or a CAI... the key is to hang on to the original parts. :)
Collectors want all origional, otherwise it is just a hack job even if the mods are done correctly. But buying a car to have it stored for 20+ years just to have it worht as much as you paid for it isn't an investment. Drive it, mod it, and enjoy it.

If you want an investment, it is never in the form of a car. End rant and back on topic with the rear.
 

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Collectors want all origional, otherwise it is just a hack job even if the mods are done correctly. But buying a car to have it stored for 20+ years just to have it worht as much as you paid for it isn't an investment. Drive it, mod it, and enjoy it.

If you want an investment, it is never in the form of a car. End rant and back on topic with the rear.
+1 You may have kept nominal value, but lost actual value through inflation... so it really isn't worth it.
 
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