I have the new engine... now help me keep from breaking everything!
 

Hello guys, I am getting ready to drop in an engine with roughly 360-400 HP and 450-500lbs. ft.

I have a few chassis upgrades such as LCA's, SFC, Front tower strut. etc...

What will I need to do with the rear end? Is it worth it to upgrade the one I have or to buy a new one? The car will see the strip every now and again but will mainly be a daily driver. It also needs to be cost effective.

It is an 87 IROC.

What about the tranny? I am looking to drop in a 5 or 6 speed. How much do you think I could get roughly for my 700r4? It is in great shape. What manual tranny do you suggest that will take the punishment?

What other upgrades will I need to support this extra power?

Thanks!

Oh and if it matters... the rear end thats in it now is the 10 bolt.

AFAIK trying to build up a 10 bolt is a lost cause, i think you would be alot better off with swapping it out for a 12 bolt or getting a 9" rear.

As for the trans, 700R4s are worth very little unless its a built up trans which still arent worth a whole lot used.

Would I do good to find a rear end out of a junk yard or something? What year had the strongest?

The general consensus, I think, is that the 9-bolt is the strongest stock rear end. You might locate one in the boneyards.

JamesC

Unless you're pretty good at fabrication and modification, forget a JY rear. The torque arm mount is the big hurdle, axle length is the next.

Moser and Strange make rears that will bolt in. You can get either a 9" or 12-bolt. Each have their advantages. Factory 9" aren't as strong as their reputation would lead you to believe, but the aftermarket supports them very well.

T56 or Tremec are probably the best choices for overdrive manuals these days. You should be able to get a couple hundred out of your TH700.

Since I don't have enough money to do all of this at the same time, how will my tranny I have now hold up with the extra power? I hear they are pretty good once built up but how will it do stock?

I guess what I am asking is what will break first lol.

Your budget.

It all comes down to how it is driven. If you don't get on it all the time, both the tranny and rear will last a long time. If you're constantly getting into it, the transmission will probably go first. With a manual tranny, it'll probably be the rear.

Alright, well thanks for the help guys. At least I know that if I take it easy everything will hold up for awhile.

Yep all depends how you drive, the 700R4s can die pretty easily behind a smogger 305 if its getting bagged.

Yes your best bet if your not an experienced fabricator is to get a pre built 9" or 12 bolt that is made for a direct bolt-in to an f-body. But you could always go to the JY and pull a whole bunch of 10 bolt rears and stockpile them :p

What do you guys think of the article on this website, "beefing up the 10 bolt"

I am still curious if this is not the way to go. The directions from that article seem pretty easy. The total cost was something like $800.00

Would it not be worth it?

Thanks for your help.

I believe the drop in 9" and 12 bolts are in the 1300-1500 range, i would definately say spend a few bucks more on them.

That's what I wanted to make sure of. Thanks again!

Hello Guys, New to the forum. Been lookin for a site like this for years. Anyways I can shed a little light on this topic from past experience. If the car is not going to see the strip much, having and aftermarket posi such as an alburn or Eaton will dramatically increase the strength of the 10 bolt. I had an alburn in for years( See Sig) and it is seen it's fair share of the track running 12.15's with 1.78 60' with no problems what so ever. Even the axles looked good. If you have the funds then sure get the 12 bolt or 9 inch. Nothing like having a peice of mind when dropping the clutch but if it's going to see mostly the street a beef up 10 bolt should hold up just fine IMO.

I have a 9 bolt and its holding up good. Last Dyno i was putting down 422 TQ at the wheels.

You'll need to put brakes on.

Eaton and Auburn say not to use synthetic gear lube with their posi units. Therefore, I won't use Eaton or Auburn.