8.25" rear rebuild....thoughts???

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superdart

superdart

Shade Tree Tinker Gnome.....
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OK..first off, my Dart is street car. The first words out of my friends mouth when I told him I had a mild 360 with a 904 and 8.25" were "That drivelines got to go." Then he preceeded to tell me how it was required to have an 8.75 rear for easy center changes when I go to the track...

Somewhere in there he forgot I was not building this car for the track.... :scratch:

My plan is to build an A-999 for a transmission later. For now the 904 is pretty fresh, and I won't be beating on it until the rearend is redone.

I have a 8.25" open diff with 2.45s...It was originally a 318 car. My motor is a 9:1 360, .030 over, ported iron heads, Airgap intake, 624 Carter, 450/475 cam, comp headers, electric fuel pump, Stage II FBO ignition, blah blah blah......

I have gotten opinions before, and many people say the 8.25 will stand up to what I've, as long as I build it right...

My question: What is RIGHT? What axles? What Limited slip unit? Will a factory SG be good enough? I plan on installing rear discs and a set of 3.55 gears.
 
superdart said:
Then he preceeded to tell me how it was required to have an 8.75 rear for easy center changes when I go to the track...
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You know every time I hear this comment I shake my head! Would seem to me it would be a pain in the *** to swap between center chuncks all the time.
 
Not so much for him...

He is drag racer..that's ALL he does..he looks at every part as though it'll need to stand up to a 500 Hemi with a trans brake...
 
I think there are other considerations here..He may have sounded slightly off kilter, but his heart was in the right place. (BTW, it takes roughly 1 hour to swap chucks on a floor jack, jack stands, and hand tools..Longest time is spent trying to get the oil out and the gasket surface clean)
The 8.25 rear was offered behind V8s, and will live with a certain amount of abuse. Here's that catch..You dont have any of the decent parts..You need a Sure Grip unit, bearings, and a ring and pinion for starters..Personally, I would bother with it, when a complete bolt in used 8 3/4 rear with brakes is for sale on this site for $400-$500, the 500 one with 3.55s. But, from an engineering veiw, it will last..Dont know how long, that depends on how you drive...If I had a 360 in an A body, I'd break the rear..Maybe after a week, maybe after a year, but I hate doing things twice (especially paying). I'm not sure what is offered for aftermarket axles either, now that I'm thining about it, and the axles will most likely be the weakest part. If the rear you had was a Sure Grip, with the wrong gears, then maybe I'd use it, but thats really the only way. I've had very good luck with used 8 3/4s because they are so hard to break anyway. Just my $.02
 
Look tell your buddy this...If you are not using slicks or a 12 inch tire the rear will last..If the tire is spinning and I am sure it wil..There is less stress than if you were using a sticky tire..I have been beating and I mean beating the loving crap out of a 8.25 in a Dakota (that I drag with slicks 26/10/15)..I am into the low 14's and I have not blown up the rear end..In your combination it will last..
 
i would not worry to mutch, i have a 8 1/4" rear that has lasted thru lots of abuse behind a hardshifting 904gearbox and a nervous 340.. im running M/T indy ss on my car most of the time but when i know i want to push it hard it has hoosier QT 275/55´-14...
 
I wouldn't worry about abusing it with a 360, 8 1/4 rear end came stock behind a lot of 400's.
 
Mopar - I know he's only looking out for me...He's just not in my world. http://www.racingjunk.com/exec/ca/view/385893/37-CHEVY-COUPE-PM-TS.html

Ran 6.80s...at 200+ (The car is now sold).

The way I look at it..I will never go above 275 street rubber..I'll spin the tires before I'll snap an axle - I think.

New questions: Will a $500 8.75 be drop in ready? I doubt it. How much conversion work is required for my car? I have all BBP axles.. that means a redrill is in order. Plus I STILL need to get the disc brake conversion.

Sure an 8.75 would be nearly bulletproof for me, and I'd love to have one, but it may not be feasible. But if a 8.25 will stand up to me...I'll use what I have.

So what IS required to swap to a 8.75?
 
superdart said:
Mopar - I know he's only looking out for me...He's just not in my world. http://www.racingjunk.com/exec/ca/view/385893/37-CHEVY-COUPE-PM-TS.html

Ran 6.80s...at 200+ (The car is now sold).

The way I look at it..I will never go above 275 street rubber..I'll spin the tires before I'll snap an axle - I think.

New questions: Will a $500 8.75 be drop in ready? I doubt it. How much conversion work is required for my car? I have all BBP axles.. that means a redrill is in order. Plus I STILL need to get the disc brake conversion.

Sure an 8.75 would be nearly bulletproof for me, and I'd love to have one, but it may not be feasible. But if a 8.25 will stand up to me...I'll use what I have.

So what IS required to swap to a 8.75?
Click to expand...

I am about to do a swap from a 7 1/4 to 8 3/4 and I can testify that $500 will not do a direct swap. No matter how you go about it!
 
I agree, I just do not see A-body 8.75's much and they ones that are complete are much more than $500 unless they are in need of a rebuild. Plus superdart has a 75 which very likely has the large bolt pattern front wheels so the cost of converting the rear 8.75 to big bolt pattern needs to be factored in.

Last year I picked up an 8.25 for the price of a case of Bud. It was already a sure-grip but had 2.9 gears. I purchased 3.55's from Randy's for $175 and a master bearing kit for slightly less than $100. Took a Saturday morning to rebuild.

A sure-grip can be purchased for $175 to $500 depending on what you get and good quality axles are $130 from Randy's
 
wel, I'm fairly well connected, so perhaps my experience isnt typical..But my case and axles were $50..the chuck was free, but my buddy didnt count the teeth, so now I owe him for the 3.55s..lol. As far as bolt in, if it's sold as a complete rear..It is bolt in into your car. you should have the small ujoint, so you could reuse that too. You would need the larger shock plates if yours are not for a 3" axle tube..The 7 1/4 ones are not that big..8 1/4s are I think. Your brakes will dricetly bolt on, backing plates and all, although a complete rear should have brakes, they would most likely need servicing to be safe enough for me to drive. Brake cables go with the brakes, as do the steel lines and hose. I do admit, this gives you small bolt rear axles, so you'd want to change them, but on a budget, you could make do for a time until the $$ comes in.
As far as buying the parts, I wqouldnt want a $17? sure grip..new or not. A good one is $300 at least, then theres the ring and pinion, and the install kit. so we're up to $600 or so, and if you cant do the setup on your own (it's not hard, but you do need a press at minimum..) add another $300 or so ($65/hr times 5 hours) plus oil, axle seals (best time to do them) and you're now at right around $1000. Realistic math sucks. again, IMO, an 8 3/4 full rear, even as a core, will be either close to the same $$ but much stronger, or a bit less with the small pattern left in place for a time. Obviously, just my choice, it's your car. I know I can break them....hehe.
 
moper said:
wel, I'm fairly well connected, so perhaps my experience isnt typical..But my case and axles were $50..the chuck was free, but my buddy didnt count the teeth, so now I owe him for the 3.55s..lol. As far as bolt in, if it's sold as a complete rear..It is bolt in into your car. you should have the small ujoint, so you could reuse that too. You would need the larger shock plates if yours are not for a 3" axle tube..The 7 1/4 ones are not that big..8 1/4s are I think. Your brakes will dricetly bolt on, backing plates and all, although a complete rear should have brakes, they would most likely need servicing to be safe enough for me to drive. Brake cables go with the brakes, as do the steel lines and hose. I do admit, this gives you small bolt rear axles, so you'd want to change them, but on a budget, you could make do for a time until the $$ comes in.
As far as buying the parts, I wqouldnt want a $17? sure grip..new or not. A good one is $300 at least, then theres the ring and pinion, and the install kit. so we're up to $600 or so, and if you cant do the setup on your own (it's not hard, but you do need a press at minimum..) add another $300 or so ($65/hr times 5 hours) plus oil, axle seals (best time to do them) and you're now at right around $1000. Realistic math sucks. again, IMO, an 8 3/4 full rear, even as a core, will be either close to the same $$ but much stronger, or a bit less with the small pattern left in place for a time. Obviously, just my choice, it's your car. I know I can break them....hehe.
Click to expand...


8 1/4" rears have 3"tubes!
 
I understand what you are saying, Mopar. I too can break them...hell, I can break anything if I try. But to me there is a diference between driving something "hard" and just plain doggin' the piss out of it.

Fat chance of my going to SBP wheels....I just bought 15x8 Draglites..oh yeah...that brings up another point..redrilling the axles can be done, but what of the disc brake kit...I'd have to have the rotors specially drilled too....more $$$$......it never ends.

But I digress......

With a 9:1 360 4 barrel...does anyone think a MP Suregrip with 3.55s and stock axles would be durable enough for street rod duty?

I'm also thinking about going instead to a Detroit Locker and Mosier axles..
 
superdart said:
With a 9:1 360 4 barrel...does anyone think a MP Suregrip with 3.55s and stock axles would be durable enough for street rod duty?

I'm also thinking about going instead to a Detroit Locker and Mosier axles..
Click to expand...

I think you will be fine with that combo! I have allways been told that Lockers will tear up your tires on a streeet car.
 
The one I currently have in my Barracuda was behind a 360/380 crate motor for several years when the owner fell into one of those rare deals on a built 8.75.

I have another buddy with an 8.25 behind a very stout 360 in a Barracuda, he is running 4.10's and a A518 tranny.
 
I dont make myself out to be a psychopath behind the wheel, but I know there will be at least one time where I will do something that will exceed the capacity of the rear.. I have a good reputation of not having broken cars, even when I do occasionally drive/race them hard. Cruise night duty is fine for the Mp and stock axles. so is commuter duty. I wouldnt race it, or put good tires on it tho..(burnouts with cheap street tires are OK tho :thumleft: )
 
lol....Yep....driver...club cruises & cruise nights...little bit o playing..but that is all....

Mopardude - I thought it was a SPOOL that would tear up tires? I hear the newer style Detroits are much more forgiving on the street.

Mute point, if I run with a SureGrip..dealer quoted me a good price on a new SG....even WITH tax it will be less that Summit. Going to keep shopping though.
 
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