Is my rear end strong enough
- Thread starter Resto
- Start date
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68gtxman
I used to reMember
Doing a lot of burn outs? Going drag racing? If so, then upgrade. If not, then use what you got.
You could always just upgrade after you break it.
You could always just upgrade after you break it.
They're stronger than a 741. At least they have a larger pinion shaft. It doesn't mean they're stronger but they should at least be comparable. Gears matter. The lower the gears, the less stress they are subject to. What tires?? Slicks at the track or street tires on the street? Last is the engine and drive train. A stock engine converter doesn't hit near as hard as a built engine with a higher stall converter.
Sorry if I haven't been any help.
Personally, I think they're plenty strong and will more than hold up. If I'm wrong the worst you have to do is replace it. Which is what you need to do anyways if it's deemed to be too weak.
Sorry if I haven't been any help.
Personally, I think they're plenty strong and will more than hold up. If I'm wrong the worst you have to do is replace it. Which is what you need to do anyways if it's deemed to be too weak.
younggun2.0
Well-Known Member
run it until you get the new combo all worked out and tuned well. when it starts making power and running well the weak links start showing up. if you start replacing parts that will work with parts that are meant for future plans you will have a car that is apart alot longer and cost alot more. i did exactly that and it took me 10yrs to get my car back on the street.
BS on upgrading. I have a friend who has a Demon that had an 8 1/4 in it. Car ran 11s yankin the wheels leavin. He upgraded to an 8 3/4 but not because he broke anything. He was upgrading the whole car. He still has the 8 1/4. They are plenty strong.
72ScampTramp
Scamp Tramp
Talk to wormanator. He has a BB duster running 11s with a 8 1/4.
swinger340
Well-Known Member
Have seen a 72 4 speed roadrunner and a 1/2 ton pick up both with 440s and a 72 swinger with a built up 360 take poundings and do lots of burnouts w 8 1/4s for yrs w/o blowing up. Id run what you got.
Woods74
Broke Senior
Look into the 8.8 swap too. It's one of the top sticky's in transmission/drivetrain.
The 8 1/4 (actually 8 3/8) pinion diameter is 1.625. That's 1 5/8 for the decimal impaired. The GM 12 bolt pinion diameter is........wait for it.........1.625. I've seen 12 bolts take in excess if 1000HP. Course they had good stuff in them. I'll be damned If I would swap in some inferior phord crappola when what you have will work just fine.
66dartman
Well-Known Member
Only thing is those pesky c-clips.... Sure is easier to set one up than a dana, like those adjustable carrier bearing spanners. Should hold up until you break an axle.
moper
Well-Known Member
It's not usually the pinions that shear. It's ususally the caps that flex and move. The 81/4 is a decent rear. If it has the gearing and differntial you want I'd leave it and if it breaks, upgrade. If you have to go through it, re-gear, or add a limited slip unit - just upgrade now. I wouldn't spend much on it.
I've seen that arguement before too. But in all my years around cars, I have seen precious few c clip buttons broken. They don't hold a load at all. They simply keep the axle in place. It's a good rear end.
I've actually been looking for one for a long time to trade for my complete 8 3/4 sure grip under my 63 Dart, but no one's ever come through. I guess my little slant car will just have overkill, and that's fine too. lol
Only someone standing close to you could answer this question. Or you could sit in a bath tub and smell the bubbles.
metallidart
member me?
I'm going to go through mine, add a sure-grip, and hope it lasts for a little while behind my 422. I won't be running sticky tires though.
I agree. I put well over 450hp through an 8-1/4 in a 4800lb truck and ran 12's all day long for years in it. The trans lost 2nd gear before the rear end even blinked at the power.
wanta68cuda
Well-Known Member
Dang!!! Where were you four month's ago when I was trying to sell or trade my 8 1/4 sure grip!!! That's always my luck. LOL:banghead:
Steve Reynolds
Member
We drag race a 71 Demon, 440 rb 727 & 8 3/4, 4.30 gear, runs low 10's on foot brake. Broke 2 ring and pinions and cases (489) and 1 sprag. Going to a dana cause I put in a trans brake, don't want to take any more chances.
Steve
Steve
If you didn't put a crush sleeve eliminator in that 489, there's your reason. 489s with crush sleeves and 742s usually hold up at those ETs.
inkjunkie
Well-Known Member
Or just cup your butt, let one rip and smell your hand......just in case you do not have a tub in your house....
Steve Reynolds
Member
Crush sleeve eliminator was in both 489 cases, the main cap on right side broke both times, but after 400 + runs & more the ring & pinion & the case said enough.
Steve
74 Duster full interior.
We call it the trainer car because you have to learn how to cut lights before you get in one of the faster cars.
8 1/4 rearend with 3.91 gears and sure grip.
Smog engine with a few up grades.
Runs 12.21 off the juice and 11.59 with 100 hp of juice.
Well over 300 pass's with the 8 1/4.
Waiting for it to brake.
Road hard and put away wet.
3200 lb car.
Trainee Jon.
We call it the trainer car because you have to learn how to cut lights before you get in one of the faster cars.
8 1/4 rearend with 3.91 gears and sure grip.
Smog engine with a few up grades.
Runs 12.21 off the juice and 11.59 with 100 hp of juice.
Well over 300 pass's with the 8 1/4.
Waiting for it to brake.
Road hard and put away wet.
3200 lb car.
Trainee Jon.
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