Slant Six Forum :: The Ultimate Donor Car?

No car was ever factory built with an 8 3/4 rear axle and large bolt pattern disc brakes.

The only benefit I see to the 8 3/4 over the 8 1/4 in a low hp car is the ability to do gear swaps...but how often do you plan to swap gears?

One thing I like about the 8 3/4, that is their taper-roller type axle bearings with end play adjustment not a ball bearing. (Doc)

The other benefit the 8 3/4 adds is you won't have to worry about shearing an axle shaft off at the C-clip if you decide to autocross the car or are doing a lot of canyon carving.... (DusterIdiot)

Quote:

The only benefit I see to the 8 3/4 over the 8 1/4 in a low hp car is the ability to do gear swaps...but how often do you plan to swap gears?

The other benefit the 8 3/4 adds is you won't have to worry about shearing an axle shaft off at the C-clip if you decide to autocross the car or are doing a lot of canyon carving....

The 8 1/4" sure grips for our vehicles are good to 1997, after that they changed to a 29 spline axle shaft...

-D.Idiot

Quote:

One thing I like about the 8 3/4, that is their taper-roller type axle bearings with end play adjustment not a ball bearing. (Doc)

Quote:

The other benefit the 8 3/4 adds is you won't have to worry about shearing an axle shaft off at the C-clip if you decide to autocross the car or are doing a lot of canyon carving.... (DusterIdiot)

Restoring/Renovating the car to be safer, handle better, and just be all around more driveable, not alot of straight-line speed.
I would just stick with the 7 1/4 rather than swap to an 8 1/4.

You ever had that happen? Ive never had a problem with the 8 1/4 in any vehicle that I have had,and I beat my junk like crazy.

Its really not much,I think an inch wider overall. The 7 1/4 gets a lot of crap but its a good axle,the weak spot is the spider gears. If you are not planning to do nutral drops or drag racing,it will last.

Author:	Danarchy [ Thu Feb 09, 2012 8:34 pm ]
Post subject:	The Ultimate Donor Car?
The more I take things apart, the more I realize I want to change as much as I can all at once. Information I am looking for would be what cars should I look for in the salvage yards to get LBP Front Discs for a early A-Body conversion (73-76?), and would any of the same cars have a 8 3/4 rear end with the LBP (non A Body?) Is there an *Ultimate Donor Car* that has all these parts? Conversion of 1964 Dart GT to Disc brakes and rear end with multiple ratio options.

Author:	Reed [ Thu Feb 09, 2012 8:59 pm ]
Post subject:
No car was ever factory built with an 8 3/4 rear axle and large bolt pattern disc brakes.

Author:	DusterIdiot [ Thu Feb 09, 2012 9:02 pm ]
Post subject:	Yes and no...
The 8 3/4 stopped being offered in A-bodies in 1972 so if you found a LBP version someone made one with cut down C- body axles or redrilled flanges... The 1973-1975 could be a good all around donor for most parts: Front Disc Brakes Suspension Parts that have inexpensive replacement parts. There are only 2 stock torsion bars in 90% of the cars (the base /6 bar is the same as the V-8 bar for pre-72, there is a third T-bar but you'd be lucky to find a Taxi/Cop Car Valiant) Steering box Possibility of an 8 1/4" rear EI Harness Electronic VR Possibility of Clutch Fans and Radiator Shrouds Other bolt on options for '67+ like mirrors/etc. 1976 is an odd final year so lots of 'refinements', and some items are not as transferrable (wiring, Instrument Cluster circuit board, etc), but these have the best chance of having Disc Brakes as they were made a mandatory item on cars built after 1-1-76. Early cars (pre-66), you are going to be looking over different years to mix and match what you need ('72- rear end, 73+ disc brakes, C-body axle shafts, etc....) Usually you can get everythign you want by buying a project car the owner lost interest in and looting it for what you need and selling the rest or keeping it in case you need spares. -D.Idiot

Author:	Danarchy [ Thu Feb 09, 2012 9:06 pm ]
Post subject:
Quote: No car was ever factory built with an 8 3/4 rear axle and large bolt pattern disc brakes. Thanks Reed,that's what I needed to know.Bummer, but I was wondering if there was a Holy Grail!

Author:	Danarchy [ Thu Feb 09, 2012 9:14 pm ]
Post subject:
D.I.- I found most of these parts locally(junkyards), but only drum cars and 7&8 1/4 rear ends. I'll keep looking.-Thanks -Steering box -8 1/4" rear (really want to find a 8 3/4) -EI Harness -Electronic VR -Clutch Fan -Radiator Shrouds

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Author:	raPoM [ Thu Feb 09, 2012 9:28 pm ]
Post subject:
If you are keeping the slant and don't plan on going over 400 hp/tq the 8 1/4 is more than enough for your car, and will have less parasitic loss compared to the 8 3/4. Parts like gears/limited slips are cheaper for the 8 1/4 too, and can be found used even cheaper. I got my gears from a Jeep guy (some jeeps run 8 1/4's) and my trac lok from a 95 Dakota. The only benefit I see to the 8 3/4 over the 8 1/4 in a low hp car is the ability to do gear swaps...but how often do you plan to swap gears?

Author:	DusterIdiot [ Fri Feb 10, 2012 5:36 am ]
Post subject:	...and
Quote: The only benefit I see to the 8 3/4 over the 8 1/4 in a low hp car is the ability to do gear swaps...but how often do you plan to swap gears? The other benefit the 8 3/4 adds is you won't have to worry about shearing an axle shaft off at the C-clip if you decide to autocross the car or are doing a lot of canyon carving.... The 8 1/4" sure grips for our vehicles are good to 1997, after that they changed to a 29 spline axle shaft... -D.Idiot

Author:	Danarchy [ Fri Feb 10, 2012 7:30 am ]
Post subject:
Quote: One thing I like about the 8 3/4, that is their taper-roller type axle bearings with end play adjustment not a ball bearing. (Doc) Quote: The other benefit the 8 3/4 adds is you won't have to worry about shearing an axle shaft off at the C-clip if you decide to autocross the car or are doing a lot of canyon carving.... (DusterIdiot) Restoring/Renovating the car to be safer, handle better, and just be all around more driveable, not alot of straight-line speed. I would just stick with the 7 1/4 rather than swap to an 8 1/4.

Author:	raPoM [ Fri Feb 10, 2012 9:12 am ]
Post subject:	Re: ...and
Quote: Quote: The only benefit I see to the 8 3/4 over the 8 1/4 in a low hp car is the ability to do gear swaps...but how often do you plan to swap gears? The other benefit the 8 3/4 adds is you won't have to worry about shearing an axle shaft off at the C-clip if you decide to autocross the car or are doing a lot of canyon carving.... The 8 1/4" sure grips for our vehicles are good to 1997, after that they changed to a 29 spline axle shaft... -D.Idiot Rob- You ever had that happen? Ive never had a problem with the 8 1/4 in any vehicle that I have had,and I beat my junk like crazy. Not to mention all the drifters/auto cross mustang guys with 400+ hp running the stock 8.8 (c-clip axle) with no problems.The only constant issues I have heard of/witnessed with c-clip axles is with the off road jeep/dakota guys,and then they just run c-clip eliminators.

Author:	raPoM [ Fri Feb 10, 2012 9:14 am ]
Post subject:
Quote: Quote: One thing I like about the 8 3/4, that is their taper-roller type axle bearings with end play adjustment not a ball bearing. (Doc) Quote: The other benefit the 8 3/4 adds is you won't have to worry about shearing an axle shaft off at the C-clip if you decide to autocross the car or are doing a lot of canyon carving.... (DusterIdiot) Restoring/Renovating the car to be safer, handle better, and just be all around more driveable, not alot of straight-line speed. I would just stick with the 7 1/4 rather than swap to an 8 1/4. The save yourself some money and HP and just stick with the 7 1/4. An 8 3/4 is not "safer",and the 7 1/4 is slightly wider than a stock A body 8 3/4 so it will handle slightly better.

Author:	Danarchy [ Fri Feb 10, 2012 9:39 am ]
Post subject:
Thanks RaPoM! probably will stick with the 7 1/4, I didn't know the 8 3/4 was narrower? (any idea how much?) "safer" was in reference to disc upgrade and 9">10"rear drums!

Author:	raPoM [ Fri Feb 10, 2012 10:39 am ]
Post subject:
Hahaha I understand now! Just look for a BBP 7 1/4 with 10" drums,sometimes you can get lucky and find someone giving them away. Even at that, your car is very light,and with front discs the 9" rear drums will be adequate. Its really not much,I think an inch wider overall. The 7 1/4 gets a lot of crap but its a good axle,the weak spot is the spider gears. If you are not planning to do nutral drops or drag racing,it will last. When I first got into mopars/slants I always had 7 1/4's,even behind some mild motors,and never had a problem. I started running 8.75 for the gear options/availibility,but then the prices shot up like crazy So I started running the 8 1/4,and have not had a problem. Im running one in my truck right now,and I love it. The truck is heavy and a manual trans and I beat the crap out of it.Its getting 4.56's and a trac lok very soon

Author:	DusterIdiot [ Fri Feb 10, 2012 6:43 pm ]
Post subject:	Not yet...
Quote: You ever had that happen? Ive never had a problem with the 8 1/4 in any vehicle that I have had,and I beat my junk like crazy. I haven't, others in the area have...usually it involves turning a corner and dumping the clutch on a V-8 not built for the street. I know that it also happens if you don't regularly check your rear-end (that 150,000 mile rear-end oil's really good for the diff). -D.Idiot

Author:	kesteb [ Sat Feb 11, 2012 6:18 pm ]
Post subject:
Quote: Its really not much,I think an inch wider overall. The 7 1/4 gets a lot of crap but its a good axle,the weak spot is the spider gears. If you are not planning to do nutral drops or drag racing,it will last. BS, they are not wider, all A-body axles measure 56.5" from the wheel flanges. There may be differences when measuring from the brake backing plates. But that doesn't determine the track width.

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Author:	sandy in BC [ Sat Feb 11, 2012 6:51 pm ]
Post subject:
The 7.25 is a weak axle that needs expert attention to last even behind a stock slant. Mixing disc brakes and 9 " drums is unnecessary and foolish.