Is a 10 bolt strong enough?

73guna · Mar 27, 2004

Is a 10 bolt rear end strong enough for 500 hp and 500 + ft. lbs of torque. I have a 1973 Chevelle w/ a 10 bolt and want to upgrade to 4.56 gears and a posi but dont know if my rear end will support that much power. It will primarily be used as a street car but the ocassional drag strip run will be there. If I use good quality internal parts will this be enough? Mostly concerened about drag racing if it will break during the launch. Unfortunately 1972 was the last year for Chevelles w/ 12 bolts and my only other option would be to modify a 12 bolt or ford 9" which might be out of my budget. I'll have about $1500 to spend. Car is an auto.What to do.....
Mitch

71chevy0192 · Mar 27, 2004

Basically what it's going to come down to is how hard you are launching. If you are only going to be using street tires, then you should have no problem with using a 10bolt; however, if you are going to use drag radials or slicks and a trans brake, or high stall, that's a different story.

big gear head · Mar 27, 2004

Your car has the 8.5 10 bolt, which is a pretty good rear end. There are several things that you can do to it to make it better. The first thing to do would be to get a 30 spline Eaton posi and 30 spline Moser axles. The Eaton is a stronger differential than what GM used in these rear ends. The 30 spline Moser axles will be about 40-50% stronger than the stock 28 spline axles. Having it is set up correctly with a good ring & pinion and Timken bearings will also help. You can install a T/A aluminum cover to strengthen the bearing caps and housing. I recommend welding the axle tubes to the center casting in the 8.5, they seem to be prone to twisting the tubes in the cast iron center. This needs to be done by a professional welder with experience welding cast iron. If you build it this way it should handle what you will be putting through it. The only difference between this and a 12 bolt is 3/8 difference in ring gear diameter and the size of the differential bearings.

If you consider swapping the rear end for another you should look at a 9". The '72 and earlier rear ends have the eyes cast at a different angle on top, so adapting a 12 bolt to your car can be difficult.

I'm looking at a '73 Laguna. I'm waiting for the owner to give me a price. It's all original and in pretty good shape.

73guna · Mar 28, 2004

Thanks ,71chevy0192 , Im gonna use slicks thats why Im concerened about twisting something . Maybe go a little easier on the launch or just stick w/ street tires. Thanks for the input big gear head. I plan on using good quality internal parts as you suggested and welding the axle housing to the center sounds like a good insurance policy I'll have to try. Good luck on your Laguna purchase. My 73' is actually a Laguna also. Just picked it up last spring and am starting to restore it. Has 33,000 " rough " original miles. Ive always been a big fan of the gen. 3 Chevelles , this is my second one and hope to own more!
Thanks , Mitch.

71chevy0192 · Mar 31, 2004

Good luck. I'm sure it'll be fine.

tpshea · Apr 1, 2004

Mitch,

You said that this will be primarily street driven? If that is the case, you are probably not going to like the 4.56 very much

after the first couple of fun blasts. Way too much gear for a street machine

(IMHO) unless you are also planning some type of serious overdrive. Check out the other posts here in Transmissions.

73guna · Apr 2, 2004

I owned a '73 Chevelle w/ 4.10 gears and I loved it , I had fairly good drivability on the street but I was using a 275/60 r15 tire which could have lost some of my ratio. Is a 4.56 gonna rev my engine that much more? I plan on using
N-50 tires but dont know the diameter yet. Are these taller than the 275 series tire? '73 Chevelles are very heavy , probably 4000 lbs without me in it, add a 200 lb lard a#* like me.... You get the picture. I'm just thinkin' I need more gear to move that boat. If I use 4.56's and have 500 hp will my first gear be to much to handle I eventually would like to add a overdrive tranny or an overdrive tailshaft to my 350 th, any one used those before?

mr 4 speed · Apr 2, 2004

I like my 12 second/low 13 second timeslips with 2.73's

I would use a Powertrax locker and even without knowing the details of your combo,I think 3.73's-4.10's is truly the outer limit for gear in a street car and drag car IMHO and experience.
BTW,an N50/15" is 28" tall

tpshea · Apr 2, 2004

Did the math, a 28" tire, 4.56 gears and a 1:1 high gear puts you at almost 3300RPM at 60MPH. 70MPH raises that to over 3800. What type of engine are you putting together for this. 500 HP either means lots of torque (big-block) or real high RPM (wild small block). If you have the big block, you will have lots of torque and will be able to move out real well without the 4.56's. Friend of mine had a small block with 4.56's in a 62 Corvette, it moved real great, however just the gas mileage alone convinced him to go back to 3.73.

73guna · Apr 2, 2004

Have a 454 block , want to stroke and bore to a 496. Not sure on the parts combo yet but it looks like Im gonna rethink my gearing to something a little more streetable , maybe 3.55's. Thanks for all the input I got more out of this ques. than I expected.

Is a 10 bolt strong enough?

73guna

71chevy0192

big gear head

73guna

71chevy0192

tpshea

73guna

mr 4 speed

tpshea

73guna

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