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Old May 6th, 09, 07:07 PM
Big Dave Big Dave is offline
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Default Bringing up the rear

SS Suspension

Part Two: Bringing up the Rear

1962-'63 Novas
The 1962-'63 Novas have a 10 bolt Hotchkiss style rear end with an 8.200" ring gear and with 28 spline axels that used pressed on axle bearings. If you have a positraction unit it will have a P cast into the outside of the drivers side of the case (it takes a special housing to run a posi). The Chevy rear end was wimpy compared with the Pontiac-Olds version (BOP) which had 31 spline axels and a nine inch ring gear. They are very hard to find today as early racers (like Don Garlits) used them all up ages ago. the spider gears are the weakest link with this rear end and that is what usually broke first.

10 bolt 8.2" Spicer rear
It was replaced in 1964 with a Salisbury style rear the exact same size 10 bolt rear end made by Spicer. The 10 bolt rears came in both Positraction and non-Positraction versions without the need for a special case. It had the same 8.200" size ring gear secured with only 10 3/8th inch bolts (9/16th inch hex heads) with a 1.438" diameter pinion bearing (1-1/8 pinion nut), and 28 spline axles but made with stronger (thicker) spider gears and case.

This new design doesn't have press on wheel bearings and the axel bearings ride right on the axel without a hardened race (The 7.5", 8.2", 8.5" and 8.875" car rear ends all use the same axle bearings, except for the big cars like the Impala which uses truck axle bearings). Instead the axles are retained by C-clips (which is a problem as the 1.200" diameter axles are the weak link with this style rear end and when they break they leave the vehicle tearing up the rear quarter panel and creating handing problems with the car). The 10 bolt rear end was installed in all vehicles that had a motor with a gross horsepower of under 300 (except for the 275 hp 327 when equipped with a 4 speed), or was not equipped with solid lifters (the measly 290 horse Z/28 had a 12 bolt under it, not because it is a torque monster, but because it had solid tappets).

The ten bolt has two carriers the first is the two series (casting number ED32118) that mounts a 2.56 and a 2.73 ring gear; and the three series carrier (casting number EDB 30116) that can mount a 3.07 through a 3.31 gear. There are axel codes stamped three inches from the case on the steel axle tube on the front of the passenger side with codes to identify what was inside it when it left the factory (same for the 12 bolt).

The 12 bolt 8.875" Spicer rear
To fill the void for a stronger rear end to handle the power of Chevrolet's new 409 (and Pontiacs 421) they introduced in 1965 a new 12 bolt rear end. The heavy duty 12 bolt used a larger 8.875" ring and pinion gear held on by 12 3/8th bolts (hence the name 12 bolt), it has a larger 1.625" diameter pinion shaft with bigger 30 spline axles (with an 1.250" diameter; which doesn't sound like much, but it yields a 24% increase in strength over the 10 bolt axles): but it also has C-clips (The small Ford Torino axle bearings require you to order special axles, so the weld on C-clip elimination axle ends and new axle upgrades need to be done together).

The 12 bolt had three different carriers to account for the change in the rings position due to the root diameter of the pinion gear shrinking as the gear ratios increased (the Ford nine inch differential moves the ring gear back and forth in the case by way of two spanner nuts so it has only one size carrier). The 12 bolt three series carrier (casting number ED 32088) supports gear ratios of only 2.56 and 2.73. The 12 bolt three series carrier (casting number 30140PM1) supports gears from 3.08:1 to 3.73:1 (4.11 in aftermarket). The 12 bolt four series carrier (casting number ED30174) supports gears from 3.90 up to 5.38 (3.73 and up to a 6.17 are available in the aftermarket).

The axels are the same length left and right so if one side sticks out more than the other it is due to the shims used to set-up the rear end (the cross-shaft inside the differential case is what centers the axles inside the housing). This is important because everyone measures from a different place to determine the overall length of the housing. The Nova needs a 60" wide housing measured from the axle flange to axle flange. The spring perches are 42-1/2" from center to center. Also don't forget that the pinion is offset 1/2 inch from center, which means that it will be 29-1/2" inches from the center of the pinion to the end of the right axle and 30" from the center of the pinion to the end of the left axle. The 1970-'71 Camaro is one inch wider than the 1967-'69 Camaro and Nova rear ends. The spring perches are 45-1/4" from center to center, and it will only have multi leaf spring perches. The 1965-'70 Impala 12 bolt is a good housing to build as it has a thicker casting and can be narrowed to fit your car. It doesn't have the eyes cast into the top like the Chevelle and later 1971-'90 Impala housings. You will need a set of weld on C-clip eliminator housing ends because the Impala uses bigger truck axle bearings and brakes. You want to pass on truck 12 bolts you find in the bone yards because the truck 12 bolt has a smaller diameter pinion shaft of 1.438", and uses the self same big car axle bearings, and the Governor Lock rear differential ("Timex Posi") is useless on pavement. It locks up based on differential wheel speed. When you get one wheel going about 100 RPM faster then the other it will lockup solid. Other then that is just like an open differential Because it lets the spinning wheel gain speed before it engages it often goes kapow and blows up taking out the entire rear end with it.

One word of caution about Oldsmobile 12 bolts out of a Cutlass or other mid size cars. They aren't 12 bolts but 8.2" 10 bolts hiding behind a sooth round 12 bolt inspection cover. The only good thing I can say about them is they have pressed on axle bearings on their 28 spline axels.

So what is so great about a 12 bolt when all I hear about are that the nine inch rears rule racing? Well the first thing I would point out is that nine inch rears do not rule racing, 12 inch rears do. What you think is a nine inch rear end hiding under the plastic body of Ron Capps, or John Force's funny car is actually a 12 inch rear end with floating axels (a billet steel alloy bar that goes through the rear end from one side to the other tying the tires together so that there is no spool). The Top Fuel and Pro Stock classes use them as well. Only the amateur classes use a nine inch rear end in competition. Let me list the virtues of a 12 inch:

1.) It is lighter than a nine inch and in racing that is important whether drag racing were every once counts or road racing were control of unsprung weight is essential to keeping a tire on the ground.
2.) There is less parasitic drag associated with the Spicer design than the Ford design which has the pinion low on the ring gear so that it can engage more surface area (which means more steel is rubbing on steel creating heat from friction). How much? Everyone says at least 2% of your flywheel horsepower is lost to parasitic drag, a recent comparison test on a chassis dyno, on the drag strip, and on a SpinTron (think of it as a reverse dynamometer) measured 3.7% to 4% loss. Both Mark Williams (93452) and Strange Engineering (PRG500) makes an aluminum case nine inch center section that use the Spicer 12 bolt gear set in a nine inch rear end with either 35 or 40 spline axles just to get around this issue (Fair warning the MW rear end system is pretty expensive at $7,080 for a complete pro rear end; but the Strange rear end is real cheap by comparison at only $1,325.37).
3.) It is as strong as a built up nine inch (able to handle 750 horsepower) with a few improvements such as steel main caps (requires line honing the case) a thick cast aluminum rear cover with preload bolts for the main caps, and welding the tubes solid to the nodular iron case (TIG weld the tubes with FM-99filler rod. Or you could MIG weld it with MG-289electrodes after scraping off the flux. The cast nodular case requires a high nickel rod to bond to the nodular iron, other wise you are creating essentially a cold weld and are still relying upon the plug weld to hold things in place). I also recommend changing out the spider gears and the end gears.
4.) It isn't a strength improvement so much as a performance tuning modification. the Eaton Positraction unit (made by the parent company Dana-Spicer and OEM to all HD 12 bolts) can be modified by changing the springs that load the clutches (stock springs are 200 pounds, but you can swap them for 400 pound or 800 pound springs), and adding more clutches and steels with the use of a thinner forged steel end gear, (and in replacing the organic fiber clutches with race-bred pyrolytic carbon fiber clutches), and finally a new cross-pin shaft to keep the Spiders from welding themselves to the shaft at high RPMs in the burn out box.

The Corporate 10 bolt rear
Beginning in 1972 and still in production today as a corporate replacement for the 10-bolt 8.2-inch or the 12-bolt 8.875-inch, is GM's "Corporate" 10 bolt rear end was used in many different models by every GM division, with the exception of Cadillac. It has a smaller 8.500" ring gear compared with the 12 bolt, but it still retained the bigger 1.625" diameter pinion shaft. Unfortunately it also still has C-clips, and when GM introduced the 8.5" rear end it had the 10 bolts 28 spline axle (the axle size was upgraded back to the old 12 bolt sized 30 splines axles in 1989 model year and 1992 for trucks). If you use an old 12 bolt axel it has to have the C-clip button ground down 5/32".to fit in the 8.5 inch posi.

In terms of identification the 8.5 cover should be smooth compared to a 8.2 with a raised v-shape it has an 1-1/4" pinion nut (internally the ring gear is held on by 7/16" bolts with 3/4" heads that uses a left hand thread). It has a two series carrier (casting number410408N0 which mounts a 2.41, or a 2.56:1 ring gear, and a three series carrier (casting number 410409N) for a 2.73 up to a 4.56 will bolt up to it.


The Corporate Ten Bolt (made by American Axle Works or AAW) was offered with the following gear ratios from the factory:
2.76
3.08
3.23
3.42
3.73
and
4.11

The ratios 4.56, 5.13, and 5.38 are available from the aftermarket

Although it would be much cheaper to find one with a Positraction unit already installed, but many aftermarket suppliers can sell you a limited slip carrier (Eaton, Auburn, or TracLoc), 28 or 30 spline axles to convert a stock non-limited-slip axle to an Eaton Positraction are not special unless you use weld on ends for pres-on Ford bearings (an Eaton does require special differential carrier bearings however compared to stock). Factory positraction rear ends will usually have a tag on the right lower cover bolt with a two, or three-digit axle code, and/or production date. Rear ends with open differentials usually have a tag located on the left lower cover-mounting bolt (which saves time in crawling under the car).

For identification purposes the corporate 10-bolt inspection cover is an 11" x 10.25" smooth oval, and doesn't have the inverted "V" of the 8.2" axle. It also has Two square shaped pegs or excess casting at the bottom of the case, the 8.2" has no extra casting marks, and the 7.5" 10 bolt has the square pegs machined with two half holes.

The also rans:
Staring 1976 GM started using the old Vega 7.500" ring gear differential in Novas in six cylinder cars. The smaller rear end has a smaller everything (26 spline axles, which jumped to 28 splines in 1990) and should be avoided at all costs. In 1987 (long after the X-body Nova had been retired) GM increased the 7.500" rear end by an 1/8th of an inch up to 7.625", but still had the lightweight axles and had numerous warranty issues.

From 1985-'90 the 9 bolt Borg-Warner rear end was used in the third gen Camaro with a 7.750" ring gear, and it comes with bolt in axle retention (no C-clips), the posi units are a cone type (Borg-Warner not made by Auburn) instead of the clutch discs. Gears installed from the factory were 2.77, 3.07, 3.27, 3.45, 3.70 (3.90 or a 4.10 is available from the aftermarket). There was also a Dana 44 (8.500" ring gear) installed by service departments to replace broken 7.625" and 7.750" rear ends as the factory was swamped with warranty claims for this sorry excuse for an differential. The bolt in Dana 44's were then later offered for sale through GM Performance Parts, but that source has since dried up. The third gen rear end doesn't fit and isn't fit for use in a Nova, so don't bother.

Where to get one:
In addition to the Chevy Nova it can be found under the Olds Omega, Pontiac Ventura, and the Buick Apollo. It was used in the Cadillacs. 1976-'79 Seville's which were based on the X body platform. From 1977-'79 they had rear disc brakes, but the wheel bolt pattern was 5 on 5 in all the years used. Except for the bolt pattern it is identical in size and end will bolt into the 1968-'79 Nova. If you have nothing as far as a rear now (or a 8.2" 10 bolt) and do not want to crawl scrap yards looking for someone else's cast offs to spend money on rebuilding in the hopes of saving a dime; the aftermarket rides to the rescue.

Moser 12 Bolt Bolt-In Housing & Axle Package Includes: All new high nickel 12 Bolt housing (for all year Novas) with 7220 GM multi-leaf spring perches (7210 if you want it for mono-leaf), 5E12333 three series (2.76-4.10 gear ratios) Eaton 33 spline Positraction differential, 7126 chromed stamped steel inspection cover, new 7900 Small Chevy Car (for Ford large press-on bearings) housing ends, Moser Custom Alloy 33 spline axles to fit Ford bearings, R12B made in USA bearings (Timken) and seals, new 8050 7/16"-20 x 2 7/8" .480" knurl wheel studs, and 9900TB retainer plates for Chevy car with Timken tapered bearing. (no 140-5746 rear Pro-Street brake kit).
Moser part Number B12HP2 SLP $1,988.00

Moser 60 Bolt-In Housing & Axle Package: Includes new high nickel Dana 60 housing with pinion snubber mounting flange (just like Chrysler OEM car), 5DLD353 Detroit Locker For a 4.30:1 and lower gears 35 spline axles, 7128 chromed stamped steel inspection cover, with PY500 1350 forged steel pinion yoke, with 7220 GM multi-leaf spring perches (7210 if you want it for mono-leaf), new 7400 8 3/4" Mopar & Dana 60 housing ends (to fit automotive instead of trucks), Moser Custom Alloy 35 spline axles (1.500" diameter), R60 made in USA bearings (Timken) and seals, 8050 7/16"-20 x 2 7/8" .480" knurl wheel studs, & 9900TB retainer plates for Chevy car with Timken tapered bearing (no 140-5746 rear Pro-Street brake kit).
Moser part Number B60HP1 SLP $2,123

Moser 9” Ford housings (for 3rd & 4th gen Nova only), are made with new heavy duty housing cores, seamless steel tubing (3” O.D., 1/4” wall), 7220 GM multi-leaf spring perches (7210 if you want it for mono-leaf), new housing ends, and new bushings. Custom Alloy Axles (28, 31, 33, or 35 spline), 9507C 1.377" I.D. 2.750" O.D. ball R9FCD bearing set-up kit, 8020 1/2"-20 x 3" .685" knurl wheel studs, and 9750 for Small Ford & Big Bearing Torino retainer plates. (no 140-5746 rear Pro-Street brake kit).
SLP $855 ($2,410 when center section added)

Moser 9 inch housing assembly nodular case with limited slip posi & comp gearIncludes: 3062STK new nodular iron case for 3.062" carrier bearing (small pinion), STL9F31 Trac-Loc Posi (for 31 splines 1.315" dia.), PS28C aluminum pinion support, PY200 1350 series pinion yoke, competition gears, assembly gear ratio's available: 3.89, 4.11, 4.29, 4.57, 4.71, 4.86 (small pinion), and Moser shipping case. (no brakes)
SLP $1,555

Both Currie and Strange only build complete 12 bolt assemblies for the 1982-2003 Camaro with a pad to bolt up the torque arm and no spring perches as the Camaro uses a modified three link suspension with coil springs.

Strange bolt-in S60 rear differential assemblies are designed to fit your Nova without any modifications. Assemblies feature: Strange designed S60 housing cast from nodular iron, Large nodular iron bearing caps, One piece center casting for enhanced rigidity, Adjuster nuts for precise and easy set-up, Fully welded tubes, Strong 9.750 in. ring gear, Trac-Loc Positraction unit for 35-Spline axles, Pro Race Hy Tuff 35-Spline axles with 1/2 inch studs. (Brake kits are sold separately.)
PRSL05 SLP $1,895

Mark Willams GM 12 Bolt assembly: Complete with MasterLine 30 spline axles, 1/2" studs, Eaton 30 spline Posi with 800 ft/lb pre-load differential, 4130 Tubes, steel main bore caps with 1/2" bolts and jig fitted suspension brackets for 64-77 A body, 78-88 G body, 82-02 F body, and most leaf spring cars. Fully assembled. less brakes (for an additional $902.00 we can add solid, drilled, or vented rotor brake kit)
MW58060-S SLP $2,925

Mark Willams Dana 60 assembly Complete with axles, bearings, 35 spline locker, choice of 8620 gears, stock Spicer pinion yoke, new housing with any MW housing end and 1/2” screw in wheel studs. (less brakes)
MW60060 SLP $3,414

Mark Willams 9 inch Ford complete M/L Economy Assembly Includes: MW571?0 9 inch steel fabricated housing with mounts, MW57460 new nodular iron case for 3.062" carrier ball bearing (small pinion), MW187S-17B Detroit Locker (for 31 splines 1.315" dia. 28 spline pinion), MW 50100 Standard "Hi-Torque" axels with 1/2" studs, MW57803 small Ford axel bearings, MW57670 aluminum pinion support, MW39008 1350 series pinion yoke, MW8620 "standard" gears, assembled gear ratio's available: 3.89, 4.11, 4.29, 4.57, 4.71, 4.86 (small pinion)
MW57050 SLP $3,371

Any questions don't hesitate to post as others may be wondering the same thing. Once again this is a little disjointed as I have been scouring catalogs for two days to get this together. I also have lots of pictures.

Big Dave

Last edited by Big Dave; Feb 27th, 14 at 01:41 PM. Reason: Added gear ratios for 8.5 inch ten bolt
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  #2  
Old May 8th, 09, 08:43 PM
Philip Philip is offline
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Default Re: Bringing up the rear

Good info Dave, again thanks for putting in the time to do the research.
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  #3  
Old May 9th, 09, 09:56 PM
big gear head big gear head is offline
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Default Re: Bringing up the rear

Good work, but a few corrections need to be made.

Quote:
the measly 290 horse Z/28 had a 12 bolt under it
The Z28 actually made about 375 HP, but was rated low for insurance and SCCA reasons.

Quote:
the three series carrier (casting number EDB 30116) that can mount a 3.07 through a 3.31 gear.
The 8.2 10 bolt 3 series is good from 3.08 to 5.13.

Quote:
(The small Ford Torino axle bearings require you to order special axles, so the weld on C-clip elimination axle ends and new axle upgrades need to be done together).
The after market Torino housing ends use the large Ford axle bearing.

Quote:
Ford nine inch differential moves the ring gear back and forth in the case by way of two spanner nuts so it has only one size carrier
The Ford uses a thicker ring ger instead of an offset ring gear flange. The spanners can't be moved far enough to make up for the offset because the differential would be way too far off center.

Quote:
The 12 bolt three series carrier (casting number 30140PM1) supports gears from 3.08:1 to 3.73:1 (4.11 in aftermarket).
This actually goes all the way to 4.88 in after market gears.

Quote:
Also don't forget that the pinion is offset 1/2 inch from center, which means that it will be 29-1/2" inches from the center of the pinion to the end of the right axle and 30" from the center of the pinion to the end of the left axle.
30 1/2 inches from the center of the pinion to the left axle flange. The offset is 1/2 inch, which makes a total difference of 1 inch.

Quote:
One word of caution about Oldsmobile 12 bolts out of a Cutlass or other mid size cars. They aren't 12 bolts but 8.2" 10 bolts hiding behind a sooth round 12 bolt inspection cover.
The "O" axle has an 8.5 inch ring gear.

Quote:
and adding more clutches and steels with the use of a thinner forged steel end gear,
The gears are not thinner, the clutch discs are thinner. You can replace the stock steel 18 disc clutch set with a steel 22 disc clutch set using the same gears. The carbon fiber clutches only have 14 discs and are for street use. Racing requires the steel clutches. The 22 disc set should be used for drag racing only and should be used with the 800 pound springs. There are also 18 and 17 tooth axle gears. The 18 tooth gears were standard and the 17 tooth gears were used in the COPO cars and Moroso Bruit Strength differentials.

Quote:
Beginning in 1972 and still in production today as a corporate replacement
The 8.5 corporate rear end went into production in '71 in the Camaro, Firebird, Impala and some A bodies. The Nova didn't get it until '72. The early A body 8.5 had press on axle bearings and no c clips. Other than this one difference the other internal parts are the same.

Quote:
If you use an old 12 bolt axel it has to have the C-clip button ground down 5/32".to fit in the 8.5 inch posi.
The 10 bolt has a .250 inch c clip button and the 12 bolt has a .312 c clip button. There is .062 inch difference between them. The 12 bolt and 8.5 10 bolt use the same c clips. The 8.2 and 7.5 use a smaller c clip.

Quote:
In terms of identification the 8.5 cover should be smooth compared to a 8.2 with a raised v-shape
The 8.2 and 8.5 covers can be interchanged. Never judge a rear end by it's cover. I have several 8.2 rear ends with 8.5 covers on them.

Quote:
It has a two series carrier (casting number410408N0 which mounts a 2.41, or a 2.56:1 ring gear, and a three series carrier (casting number 410409N) for a 2.73 up to a 4.56 will bolt up to it.
This is backwards. The 3 series is 410408 and the 2 series is 410409. There are also 4 large "8"s or "9"s cast into the same end of the case for easier identification. The 3 series is used for 2.73 to 5.13 gears.

Quote:
Rear ends with open differentials usually have a tag located on the left lower cover-mounting bolt (which saves time in crawling under the car).
Limited slip (posi) rear ends have the tag. It says "use limited slip differential fluid only".

Last edited by big gear head; May 9th, 09 at 10:28 PM.
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Old May 10th, 09, 08:40 AM
Big Dave Big Dave is offline
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Default Re: Bringing up the rear

Thanks Freddy!

I agree with everything you said and appreciate the comments. Sorry for the errors but I was cutting and pasting information back and forth and should have spent more time proof reading (and maybe getting some sleep first before editing).

Big dave
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Old May 17th, 09, 05:25 PM
Big Dave Big Dave is offline
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Default Re: Bringing up the rear

Here is a picture of a Corporate 8.5" 10 bolt rear axle. Note the two triangular ears at the bottom of the case.



Here is a picture of the difference between a 28 spline axle and a 30 spline axle.



Here is a Chevelle 12 bolt rear end:



Here is a rear end out from under an Olds Cutlass (another GM A-body) but this time a corporate 10 bolt with a 12 bolt cover.



By the way it isn't the number of bolts holding on the inspection cover that determines whether it is a 10 bolt or 12 bolt (the Olds rear isn't a 12 bolt), but by the number of bolts that holds on the ring gear to the carrier.




Big Dave
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Old May 17th, 09, 05:41 PM
Big Dave Big Dave is offline
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Default Re: Bringing up the rear

Here are a few Posi units.

The Traction Lock Rear (found under a lot of Camaro's and S-10 trucks) looks like this:



The Gov-Loc GM truck rear end looks like this before it breaks:



and after it breaks:



Here is a picture of the Eaton Positraction:



Big Dave

Last edited by Big Dave; May 17th, 09 at 10:35 PM. Reason: Correcting mistaken info (thanks Freddie)
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Old May 17th, 09, 06:31 PM
big gear head big gear head is offline
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Default Re: Bringing up the rear

Dave, the picture of the 8.5 that you have posted at the top is one of the early A body rear ends that doesn't have c clips on the axles. The picture that you have posted as a Borg Warner differential is actually a Traction Lock from the 8.5 rear end. It was used in Camaros and other cars with the 8.5 rear end, but not in trucks. They were also used in the "O" rear ends and in 8.8 Fords. The Borg Warner differential is a cone type.
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Old May 17th, 09, 11:13 PM
Philip Philip is offline
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Default Re: Bringing up the rear

Dave copy this photo to your files. It is the corporate 10 bolt that Freddie built for me many years ago. Still has zero miles on it

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Old May 18th, 09, 10:13 AM
big gear head big gear head is offline
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Default Re: Bringing up the rear

Notice the difference between the picture that Philip posted and the 8.5 that is posted at the top of Dave's pictures. See the way the cover is cut out on the sides on Dave's? That is a rear end without c clips. The rear end with the round cover has c clips on the axles. Dave, where did you get that picture? Is that rear end for sale?
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Old Mar 1st, 10, 06:56 PM
heavchev heavchev is offline
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Default Re: Bringing up the rear

Big Dave, my 62 wagon has a banjo-type (no rear inspection cover)differential which appears to be original. Am I to understand that it should have a 10 bolt as the original rear? Thanks, Charlie
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Old Mar 1st, 10, 08:28 PM
big gear head big gear head is offline
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Nope, your car has the original type rear end in it. The rear end with the 10 bolt cover didn't come out in the Chevy II until '64. If you pull the chunk out of yours you will find 10 bolts in the ring gear, which makes it a 10 bolt rear end.
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Old Mar 1st, 10, 08:37 PM
Philip Philip is offline
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BTW Freddie by the end of this month I will actually put the first mile on the differential I got from you
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Last edited by Philip; Mar 1st, 10 at 08:39 PM. Reason: Freddie beat me to it.
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Old Mar 9th, 12, 08:03 PM
monzaz monzaz is offline
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Default Re: Bringing up the rear

Quote:
Originally Posted by big gear head View Post
Notice the difference between the picture that Philip posted and the 8.5 that is posted at the top of Dave's pictures. See the way the cover is cut out on the sides on Dave's? That is a rear end without c clips. The rear end with the round cover has c clips on the axles. Dave, where did you get that picture? Is that rear end for sale?
Well if everyone is correcting everyone...lol. The round cover comes on OLDS cutlas rears and has bolt in axles... So that info is now CORRECTED.
8.5 has many many covers.
BUT WILL always have the same ring and pinion ALWAYS.

8.2 and 8.5 rear covers interchange EXCEPT for the scalloped cover can never go on a original road covered rear.

Watch out for the bolt in axle posi units as sometimes they have posi units and the open diffs can not be used in the c-clip rears as they do not have recessed pockets for the c-clips. You can always use a 8.5 c-clip posi or open unit into a bolt in axle 8.5 rear.

JUST some extras. Jim

J D Race (where you got some of your pictures from....lol. Jim
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Old Jun 5th, 12, 06:04 PM
71nova355 71nova355 is offline
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Steve
 
Join Date: Apr 2012
Location: Wichita
Posts: 32
71nova355 has a positive reputation
Default Re: Bringing up the rear

Well, unfortunately I'm only equipped with an 8.2in under my71. After doing the math on a sight that could determine your rear end gear i believe it houses the 3.08. I will be checking the passenger side to clarify such as Dave describes. One question i do want to ask since I'm with the pros, ok, just to the sides of the housing where the axle tubes start(on both sides of housing directly in the back where it meets the axle tube) there I's a small flat spot with what looks like a dimpled weld? Anyway one side has lost the dimple and left a hole. LOL very small but I'm afraid rust will begin to cause damage because of it. can I take off the cover without getting myself into a heap of trouble and inspect and put back on the cover(only needing to clean and replace gasket) and maybe use a gas tank hole patch deal to fill that pencil eraser sized hole? LOL did you get any of that. Sorry, but seriously. When refilling with fluid, I will use the best i can get, perhaps Lucas, and just squeeze it in to the square bolt hole on the passenger side? Or should I use the plastic deal pertruding out the top(passenger side) to fill? Maybe park on a slight incline to keep the differential level when doing so I don't get a false fill due to the slight angle at which she sets. You know what I'm getting at. Thanks Guys and Dave and everyone else, great job with the site!
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Old Jun 5th, 12, 07:13 PM
Big Dave Big Dave is offline
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Dave
 
Join Date: Mar 2006
Location: Tampa FL
Posts: 14,940
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Default Re: Bringing up the rear

You can not use the plastic vent to fill the rear. The fill plug is in the drivers side of the central carrier above a reinforcing rib. It is generally a cast half inch square male pipe plug.

You can drop the inspection cover at any time without doing anything other than spilling fluid. A new gasket and the rear end has no idea you ever removed the cover (it won't disturb anything).

the plug weld is a serious issue. It has apparently broken free from some hard launching in the car's past. It needs to be welded up by a pro welder as you are welding cast iron and mild steel so it takes special wire, rods or filler rod to weld up as well as skill.

Big Dave
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