The car is a 68 chevelle with a pretty healthy Big Block in it. The motor is a 454 4 bolt block stroked and bored 30 over to 489 cubic inches... 10.2 1 compression ratio, Iron Merlin rectangular port heads -gasket matche and polished bowls, 618 638 lift cam, edelbrock rpm airgap intake. Behind it is a beefy TH400 with a 3200 stall, B&M rathcet shifter, good driveshaft and beefy joints..... Now here comes the weak link... behind all that is a 10 bolt.. I dont know if it is stock.. I know it has a posi in it and the guy before be said it was an auburn and it was rebuilt...

Anyways basically the rear suspension is stock and i want to drag the car for fun and maybe some bracket racin. Now should I spend money and get good suspension for the 10 bolt and race it with that rear end thats in it or.... put slicks on it and race it with the stock suspension untill the 10 bolt breaks and then get a good rear end and suspension??? If I do that what setup should i get for street/strip I want good consisten 60 foots and daily comforts... 12 bolt or 9 inch? or what else? where can i get it? Can i get one that will bolt right in with good supension or should I find one and have it custom fabed up? Help please.. thanks alot...

Currie enterprises :cool: I am using one from them, Ford 9", 11 drums, 31 spline axels, 3.70 gear, detroit locker. Hotchkis upper and lower trailing arms with crossmember braces. Air lift bags in Hotchkis springs and some KYB gas shocks. Lots of options out there, most are fairly expensive; or stay off of the slicks and the 10 bolt would do just fine. You would be looking at $2000 plus to go this route. I lucked out and scored mine from a guy who had a change of plans for the car he was building. Sweet deal, he even thru in a new stock gas tank that had been sumped, and the Denneys drive shaft that I was needing as well. Keep your eyes and ears open, live with the 10 bolt until you find a deal graemlins/thumbsup.gif

The suspension for the 10 and 12bolts are the same ...no. So any money there should be reusable. 12 bolts are slightly more efficient and 9" are more durable. but all in all they are supposedly about equal. I think a 12bolt will be strong enough for you application. I'd play with the 10 bolt until it breaks and then get a 12 :D

plus you want your chevy to stay chevy... ;)

I thought you couldnt rebuild Auburn posi units :confused:

If someone put the 8.5 in there from a later 70's model leave it there 8.5's are as strong as 12 bolts in most cases ;)

The 8.2" 10 bolt is not hardcore strong, but will put up with a lot before it goes away. As a safety issue in a fast car you really want to get rid of the c-clip axle retainers and use at least a Ford type axle. A cheap compromise is to use a PowerTrax locker, they do a good job of holding the axles in. A c-clip axle that pops out is not a good driving experience!

I've never really thought of the Auburn Posi as a good performance choice.

An 8.5" 10 bolt from the early seventies on is a good unit, althought some bracket welding will be needed on your '68.

A 9" is definitely up to the task, but they are about 2-3% less efficient at transmitting power to the wheels vs a 12 bolt.

Everything has a tradeoff - choose whatever you like.

Thomas

Originally posted by BadBowtie30:
should I spend money and get good suspension for the 10 bolt and race it with that rear end thats in it or.... put slicks on it and race it with the stock suspension untill the 10 bolt breaks and then get a good rear end and suspension??? I don't know about you guys, but I don't think I could risk the entire car getting damaged because I didn't have a really tough rearend. What if that 10 bolt does break during a race and your axleshaft comes out? Hello Mr. $65/hour body repair man! and possibly his friends Mr. a lot more than $65/hour emergency room doctor or Mr. mortician.

I know this is a silly way to look at it, but is it really worth risking?

I'm just building my car piece by piece. I'm lucky enough to already have a 12 bolt, but that isn't stopping me from upgrading my control arms, bushings, springs, and whatever else is under there that I forgot.

If you do stick w/ the 10 bolt, at least have the axle tubes fully welded to the center section.

Thanks alot guys.. but is there any way I can find out what year my 10 bolt is? Im assuming its stock. but you never know. Also, you think I should go with hotchkis stuff and then swap it to the 12 bolt if it does break? Also what is the advantage to welding the tubes to the pumpkin?

IMO hotchkis stuff is nice but it is the same as all the other stuff just costs more. I might look elsewhere such as ssm lift bars. You want to weld the two together so under hard acceleration the axle tube doesnt seperate from the pumpkin. Thatd be pretty graemlins/clonk.gif

I went with Poly Upper control arm bushings in STOCK U shaped upper control arms. I put SSM Lift bars in for the lower control arms. I also added the Frame braces from edelbrock, replaced my springs with stock Moog springs, and used Edelbrock IAS shocks. The sway bar is in the back yard and will be going on soon, the car handles GREAT and i get VERY little tire spin but my motor isn't as radical as yours.

IF you want to use it on the street i would totally recommend my combo i can take corners @ 60mph and have very little body roll, and it hooks great.