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#1
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Limited slip question
I’m wondering if my posi is worn out . I have a 10 bolt N unit in my GTO , it has the 4 pinion posi . I’ve only slightly stabbed the throttle since I’ve had this car back on the road but both wheels grabbed . I jacked it up last night to adjust the brakes and when I spun one tire , the other side rotated backwards ? I put it in 1st gear , both went turned forward . Could it just be weak ? I didn’t rebuild this rear during the resto because I wasn’t sure if I’d like the 3.90s ( which are awesome !) just put in new axle bearings & sealed it up . It was very clean inside . It hasn’t been used since the 70s . It came out of a wrecked GTO around 75 or so I just assumed it probably has less miles on it than my car . It doesn’t make any noise or anything . I remember years ago jacking up one side and trying to make it slip per the manual , I couldn’t and I was heck of stout in those days .
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When I wore a younger man's clothes |
#2
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My "A-body" is the same. Posi is totally worn-out, no preload at all, but still works under load.
I bought new clutches, but I'm too lazy to install 'em. Maybe someday. |
The Following User Says Thank You to Schurkey For This Useful Post: | ||
#3
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No need for posi additive fluid now till new clutch’s go in.
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
The Following 2 Users Say Thank You to steve25 For This Useful Post: | ||
#4
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So it’s weak then ? My plan was if it was shot , then I’d order a Moser with 3.55s . This engine loves the 3.90’s though , u can feel it in its power band . Do I buy a moser or rebuild the N with the poor axle bearings ? I just cruise , I don’t hammer on it .
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When I wore a younger man's clothes |
#5
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Your 4 pinion posi is a cone type, not a clutch type that you can replace the clutches. You can get an Eaton clutch type posi for the 10 bolt, but they are expensive. If you have the money I'd get a brand new Moser or Strange 12-bolt with a Tru-Trac.
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1967 Firechicken, 499", Edl heads, 262/266@0.050" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3550#. 10.01@134.3 mph with a 1.45 60'. Still WAY under the rollbar rule. |
The Following User Says Thank You to AG For This Useful Post: | ||
#6
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There is a difference between spinning wheels by hand and launching. The cone and clutch units have springs whose function is to give some lockup in zero traction conditions. Even when new this only amounts to about 260 pounds of force necessary to spin one wheel without the other, and this isn't very much (but difficult just twisting a tire by hand). You say that you can still do a two wheel burnout. Your unit doesn't have enough spring pressure to offer any resistance, but a good solid launch on asphalt will allow the spider gears to push against the cones and still deliver a burnout with both wheels. It's not dead yet but might not have much time left. A good rearend person can repair your unit and restore the pre-load and insure the cones won't be grounding out anytime soon.
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Mick Batson 1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon in progress. |
#7
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Unless it's numbers matching if it spins both tires on a burnout I'd run it til it blew and then replace it with a 12 bolt/9"/Dana 60. When I was looking Strange had winter specials you might want to check out. Quick Performance is great for a 9". If you like the 3.90s why not get that on a replacement?
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Chris D 69 GTO Liberty Blue/dark blue 467, 850 Holley, T2, Edelbrock Dport 310cfm w Ram Air manifolds, HFT 245/251D .561/.594L, T400, 9" w 3.50s 3905lbs 11.59@ 114, 1.57/ 60' |
#8
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Thanks , I think I’ll just run it until it pukes then . If I can get a year or 2 out of it , I’ll have a more accurate opinion on my rear gear and my wife won’t be so wise ! This was a frame off debacle and she was pretty cool about the whole thing but I don’t want to bring up 3k on a Moser just yet .
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When I wore a younger man's clothes |
#9
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I don't know why you'd even consider a new aftermarket "killer-strength" axle assembly, assuming that the gears and housing you have are in usable condition.
At most, an aftermarket differential in your existing axle housing. $700 instead of $3K, and a do-it-yourself job since you don't have to mess with the pinion gear. Things might be different if your housing is bent, twisted, or cracked, or the ring 'n' pinion are shot because the original differential case explodes. |
#10
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Quote:
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466 Mike Voycey shortblock, 310cfm SD KRE heads, SD "OF 2.0 cam", torker 2 373 gears 3200 Continental Convertor best et 10.679/127.5/1.533 60ft 308 gears best et 10.76/125.64/1.5471 |
#11
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I would talk to OPH (Roger) ans get a 8.5" with Tru-Trac setup from him.
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#12
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Quote:
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Ken '68 GTO - Ram Air II 464 - 236/242 roller - 9.5” TSP converter - 3.55 posi (build thread | walk around) '95 Comp T/A #6 M6 - bone stock (pics) |
#13
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Quote:
At minimum you'd want aftermarket axle shafts to go with the aftermarket carrier, but realistically I don't think this is a wise use of funds. The 8.2 is just not strong enough. But I've been wrong before, and some of this depends on gearing and vehicle weight. A Firebird with 4.10s is different from a Full-Size with 2.73s. |
#14
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Quote:
Merry Christmas! 🎄 You have the engine and transmission to do the job, don’t forget the rear end.
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1964 Tempest Coupe LS3/4L70E/3.42 1964 Le Mans Convertible 421 HO/TH350/2.56 2002 WS6 Convertible LS1/4L60E/3.23 |
#15
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I bought axles and the thicker bearing plates off of Monzaz when I sealed it up years ago . I’m too lazy to ever swap on slicks and the redlines are too expensive to fry . I searched for an 8.5 for a long time but had to give up in this area . The rear is the only part not original to the car so I was hesitant to spend the money on it .
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When I wore a younger man's clothes |
#16
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Being a 4 pinion 8.2 PONTIAC STT carrier, & am assuming here that the carrier has never been sent out & rebuilt, I'd pull the carrier, mark the cast spacers left & right, remove the ring gear, clean the carrier with SimpleClean, not mineral spirits or other solvent that FedEx will raise questions about. Carefully box it in a well reinforced box, insure it for $400 & ship it up to Jim M. He will disassemble it & machine the back sides of the cones & properly shim them back up. On a 4 Piniin cone type carrier you can have this done once, then typ that's it. Years ago, I used to ship such well worn 4 pinion carriers cone type carriers to Calif & have them rebuilt. Jim is a lot closer to you & I believe offers this service.
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Buzzards gotta eat... same as worms. |
#17
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I hear that!
Quote:
Right now I'm hesitant to run it too hard because it's slippery on street tires and the rear isn't strong enough for better traction. It sure would be nice to not feel like I have to baby it and to make a few passes at the track.
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Ken '68 GTO - Ram Air II 464 - 236/242 roller - 9.5” TSP converter - 3.55 posi (build thread | walk around) '95 Comp T/A #6 M6 - bone stock (pics) |
#18
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Buy the new 12-bolt and sell the 8.2 to someone who’s restoring a GTO.
Makes the most economic sense. If you play your cards right you’ll end up with a new 12-bolt for somewhere around $2k to 2.5k. The cheaper local bargain rear end will likely be a disappointing waste of money, the new rear end built to your specs is a sure thing. I wouldn’t invest another penny in that 8.2 rear.
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1964 Tempest Coupe LS3/4L70E/3.42 1964 Le Mans Convertible 421 HO/TH350/2.56 2002 WS6 Convertible LS1/4L60E/3.23 |
#19
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I have been meaning to post a similar question regarding my 8.2" 4 pinion rear end and if it makes sense to put any money into it but Locomotive breath beat me to it. A few years ago I machined the back sides of the cones & shimmed them back up as described by Ol pinion head in post 16. It has been working well for over 10 years. I have been considering putting in stronger axles and an aluminum cover with bearing cap supports but I'm not sure it's worth investing the money. I have read that these rear ends came with hot forged or cold extruded axles, does anyone know how to identify the hot forged from cold extruded axles?
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1972 GTO 468 2 Bolt Main w/Eagle rotating assy SD Ported 295 KRE D Ports 10.8 CR OF Hydraulic roller w/ 1.65 stainless rockers Performer RPM Intake Holley 3310 780 Vacuum Secondary TH400 with 10" Continental Convertor 8.2 BOP 4 pinion 10 Bolt with 3.36 gears 11.428/118.95/1.618 |
#20
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The hot forged look really rough and have almost an apple core shape and the have a ring if you tap them with a wrench . The cast , look beefier and machined but are not , they will have a thud when u tap them . I have the cover that I bought off a guy super cheap , Yukon axles . I think I’m just a cruiser anymore so I’m undecided on what route to go . This was a frame off resto and just don’t have it in me to dump the clutch in it !
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When I wore a younger man's clothes |
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