Locking differential conversion
June 21st, 2022, 11:23 AM
#1
Registered User
Thread Starter
Join Date: Apr 2020
Posts: 8
Locking differential conversion
Hello all,
I知 currently doing a full disc brake conversion on my 1966 Oldsmobile Delta 88 and while I知 at it, I壇 like to convert to a locking differential. I have a 10 bolt rear end and was wondering if there are any other old GM vehicles that I could pick apart for what I知 wanting to do. Any suggestions?
I致e also ordered all of the parts for the rear-disc conversion kit so I知 not sure if replacing the entire rear axle is a possibility as the kit might not fit with the new axle.
Also, pros vs cons in regards to limited slip vs locking diff?
Thanks!
I知 currently doing a full disc brake conversion on my 1966 Oldsmobile Delta 88 and while I知 at it, I壇 like to convert to a locking differential. I have a 10 bolt rear end and was wondering if there are any other old GM vehicles that I could pick apart for what I知 wanting to do. Any suggestions?
I致e also ordered all of the parts for the rear-disc conversion kit so I知 not sure if replacing the entire rear axle is a possibility as the kit might not fit with the new axle.
Also, pros vs cons in regards to limited slip vs locking diff?
Thanks!
Last edited by Jason Ludtke; June 21st, 2022 at 11:32 AM.
June 21st, 2022, 12:01 PM
#2
Registered User
Join Date: Jul 2006
Location: Richfield, Oh
Posts: 1,740
1965-1970 Olds FULL SIZE cars can have this PONTIAC rear in the car... Olds used the Pontiac rear in the lesser powered NON 455 Olds cars.
SO YES 1965- 1970 Pontiac FULL SIZE cars also will have the same parts guts for your rear. Grand Prix 65 -68 CATALINA, BONNEVILLE, 2+2 CATALINA, pONTIAC SAFARI WAGON oR CAT OR BONNEVILLE WAGON 65-70, eXECUTIVE 65-70, 65-70 Parisienne....AND SO ON.
no buicks CAME WITH THIS REAR .
Jim JD Race
SO YES 1965- 1970 Pontiac FULL SIZE cars also will have the same parts guts for your rear. Grand Prix 65 -68 CATALINA, BONNEVILLE, 2+2 CATALINA, pONTIAC SAFARI WAGON oR CAT OR BONNEVILLE WAGON 65-70, eXECUTIVE 65-70, 65-70 Parisienne....AND SO ON.
no buicks CAME WITH THIS REAR .
Jim JD Race
June 21st, 2022, 12:06 PM
#3
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Join Date: Jul 2006
Location: Richfield, Oh
Posts: 1,740
Posi Limited slip locking...and so on
You should do a search here as I am sure we went though this whole thing with limited slip and locker etc.
Trucks really are the only vehicle from the factory that had LOCKERS...
Limited slip would be the term your using for 2 wheels gripping the road, Clutches, Cones, and or worm gears.
YOU DO NOT GET A CHOICE here anyway.
Only limited slip and you have to find a used one - We sell the clutches for the Eaton limited slip unit that would be in these vehicles.
You also need to get the correct SERIES carrier with the CORRECT ratio gear...If you can get everything you need out of one rear end THAT would be best.
carrier breaks are
2.73 - 2.93 3.08 3 series
3.23 3.42 3.73 3.90 4.33 etc 4 series
2.29 2.41 2.56 2 series
I hope I gotthat right.... Jim
JD RAce
Trucks really are the only vehicle from the factory that had LOCKERS...
Limited slip would be the term your using for 2 wheels gripping the road, Clutches, Cones, and or worm gears.
YOU DO NOT GET A CHOICE here anyway.
Only limited slip and you have to find a used one - We sell the clutches for the Eaton limited slip unit that would be in these vehicles.
You also need to get the correct SERIES carrier with the CORRECT ratio gear...If you can get everything you need out of one rear end THAT would be best.
carrier breaks are
2.73 - 2.93 3.08 3 series
3.23 3.42 3.73 3.90 4.33 etc 4 series
2.29 2.41 2.56 2 series
I hope I gotthat right.... Jim
JD RAce
June 21st, 2022, 12:15 PM
#4
Registered User
Join Date: Aug 2013
Location: Evansville, IN
Posts: 10,420
A locker is for truck offroading or for drag racing, but the latter is more commonly a spool. Or you weld the spiders.
Like Jim said, you want a "limited slip differential" for street performance. This will let you launch on both wheels but also turn when you need to without scrubbing.
Assuming you have a non-overdrive transmission, for performance, you would probably want the 4 series listed above.
Like Jim said, you want a "limited slip differential" for street performance. This will let you launch on both wheels but also turn when you need to without scrubbing.
Assuming you have a non-overdrive transmission, for performance, you would probably want the 4 series listed above.
June 21st, 2022, 12:19 PM
#5
Old(s) Fart
Join Date: Mar 2007
Location: Northern VA
Posts: 47,547
Hello all,
I知 currently doing a full disc brake conversion on my 1966 Oldsmobile Delta 88 and while I知 at it, I壇 like to convert to a locking differential. I have a 10 bolt rear end and was wondering if there are any other old GM vehicles that I could pick apart for what I知 wanting to do. Any suggestions?
I致e also ordered all of the parts for the rear-disc conversion kit so I知 not sure if replacing the entire rear axle is a possibility as the kit might not fit with the new axle.
Also, pros vs cons in regards to limited slip vs locking diff?
Thanks!
I知 currently doing a full disc brake conversion on my 1966 Oldsmobile Delta 88 and while I知 at it, I壇 like to convert to a locking differential. I have a 10 bolt rear end and was wondering if there are any other old GM vehicles that I could pick apart for what I知 wanting to do. Any suggestions?
I致e also ordered all of the parts for the rear-disc conversion kit so I知 not sure if replacing the entire rear axle is a possibility as the kit might not fit with the new axle.
Also, pros vs cons in regards to limited slip vs locking diff?
Thanks!
June 22nd, 2022, 04:00 PM
#6
Registered User
Join Date: Jul 2006
Location: Richfield, Oh
Posts: 1,740
NO NEW parts for this rear 8.875. ONLY NEW Bearings and seals.... ( I have those kits too. ) USED carriers and the 3.55 gear sets 8.875 PONTIAC full size from fab craft are not looking good for production. (I HOPE they prove me wrong)
THE term 10 bolt rear and 12 bolt rear pertains to the RING GEAR BOLT count. NOT THE COVER COUNT...Sometimes they macth the cover, sometimes they do not.
NO NEW POSI UNITS FOR THIS 8.875 PONTIAC full size car rear with 31 spline axles. (they will sell you a reconditioned GM unit if they have any)
Unless FABCRAFT pulls money out of their own pockets with this gear set... they will never see the light of day again. (a shame) You can not ask people to prepay for an item that may take years for enough people to lay there money down. WHAT if they go out of business. YOU will never see that money again....
I remember having to fork over 25k to get posi units machined at a shops...IT WAS scary...BUT I made good money no problem and trusted they would sell... did a bunch of runs on them.... BUT now The 9.3 stuff and customers are drying up too as fabcraft put a hurt on that and took too long getting those 9.3 gears on the market...THEY ALL WENT 9" :now.......
Now were having trouble with the 12 bolt (10 bolt ring gear 8.5 ) olds stuff from Randys...That has been on back ordered for 8 months +now. I wish i did not stop making those too. MY BAD MOVE on trusting other companies.... Live and learn.
tough world out there...I keep trying to evolve and change with the times... Running out of answers.
Jim
JD Race
THE term 10 bolt rear and 12 bolt rear pertains to the RING GEAR BOLT count. NOT THE COVER COUNT...Sometimes they macth the cover, sometimes they do not.
NO NEW POSI UNITS FOR THIS 8.875 PONTIAC full size car rear with 31 spline axles. (they will sell you a reconditioned GM unit if they have any)
Unless FABCRAFT pulls money out of their own pockets with this gear set... they will never see the light of day again. (a shame) You can not ask people to prepay for an item that may take years for enough people to lay there money down. WHAT if they go out of business. YOU will never see that money again....
I remember having to fork over 25k to get posi units machined at a shops...IT WAS scary...BUT I made good money no problem and trusted they would sell... did a bunch of runs on them.... BUT now The 9.3 stuff and customers are drying up too as fabcraft put a hurt on that and took too long getting those 9.3 gears on the market...THEY ALL WENT 9" :now.......
Now were having trouble with the 12 bolt (10 bolt ring gear 8.5 ) olds stuff from Randys...That has been on back ordered for 8 months +now. I wish i did not stop making those too. MY BAD MOVE on trusting other companies.... Live and learn.tough world out there...I keep trying to evolve and change with the times... Running out of answers.
Jim
JD Race
June 22nd, 2022, 04:04 PM
#7
Registered User
Join Date: Jul 2006
Location: Richfield, Oh
Posts: 1,740
Find your gears first... That will be the tough one.
Posi units you can still find But you may need to do a ring gear spacer trick if you can not find the correct carrier series.
Bearings and seals etc. Pretty easy...Axle bearings might be a little hard too. Get the old bearing and seals dimensions...THAT HELPS greatly as GM and the auto parts books from the auto stores most of the time do not jive.
Jim
Posi units you can still find But you may need to do a ring gear spacer trick if you can not find the correct carrier series.
Bearings and seals etc. Pretty easy...Axle bearings might be a little hard too. Get the old bearing and seals dimensions...THAT HELPS greatly as GM and the auto parts books from the auto stores most of the time do not jive.
Jim
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