i just want to know if anybody thinks my stock 7.5 rearend will break with 4.10 gears and a posi/spool and slicks. or will it be able to last a couple of seasons. running 350 sbc bout 400HPH(motor) TH350 2400 stall

 

Flip a coin, if it is heads it will break, if it is tails it will stay together. That is close to call: It MIGHT break, and yet it might be able to last you a while. It will eventually fail, but that depends on how you drive the car and luck.

 

the slicks would be the end result of it i think, with street radials it might last for awhile.

 

Living on borrowed time. Traction is always what kills them.

 

suspose to incease the strength by 40% with a girddle and welding the tubes to the center section.

 

The girdle, welding, aftermarket axels, and such will improve the strength, but you can't do anything about the 7.625" ring gear. There is only so much power that can be funneled through that. I've seen gearsets from fully braced rears rip all the teeth off the ring gear! You'd be much better off saving your money for a 9", 12-bolt, or even an 8.8, which seems to be becoming a popular swap.

 

what is a girdle

 

A girdle is an aluminum rear end cover (replaces the stock stamped cover) that has two preload bolts with lock nuts. The pre-load bolts apply pressure to the carrier bearing caps. This stabilizes the caps, in effect making the rear act as though there is no hole at the rear, and the carrier is solidly mounted. The girdle also strengthens the housing, by effectively bridging the gap at the rear of the housing.

 

I think you'll be watching one of your tires attached to part of a axle shaft fly past you on the track. Personally I'd fab up a 8.8" in your car.

 

The only problem with the 8.8 is that the same thing is likely to happen. The ring gear is bigger, but it still uses c-clips, which is usually why the axel exits the car (I've had it happen on an 8.5" 10-bolt). You can get bolt on c-clip eliminators, but they will leak with constant street use. If you do decide to go with the 8.8 get the housing ends cut off and weld on 9" ends that will allow you to eliminate the c-clips.

 

Well yeah the 8.8 uses C-clips as well, but there is a less likely chance of breaking the larger diameter axle shafts IMO. Personally I've never heard of the eliminators leaking...how does that happen exactly?

 

First, the 8.8 uses 28 spline axels, so if you've got a 28 spline ten bolt the axels aren't that much stronger. In fact, most hardcore Mustang guys upgrade to 31 spline axels for strength.

The c-clip eliminators are designed to bolt on and be NHRA legal. They were never built with the intention of running them on the street every day, or even occassionally. The seals just aren't up to the task. Also, the bearings used are typically small compared to a 9" bearing, so they aren't as strong either. This isn't usually a problem in drga racing becasuse the shafts are never loaded side to side, but this happens on the street, especially if you like to drive the car hard around a corner.

 

if i buy a 12 bolt for my car will i have to get a new driveshaft and u-joints. how will that all fit into place?

 

Explorer's use 31 spline 8.8's, I know that for sure.

Didn't know that about the eliminators, thanks.

 

If it's a thirdgen drop in, it should have the correct yoke to match to the driveshaft and u joints. Contact the manufacturer to see what needs to be modified/changed in order for the axle to function properly.

 

damn guys i have been there done that,i started braking axles,at the strip with drag radials,so then i got a set of moser axles,then i started braking the spider gears in the posi unit,so i upgraded to an eaton posi,then i stared braking ring gears i broke one right in half,then i took the teeth right off another one,so after 1200 in upgrades on the 10 bolt i finally got smart and got the moser 9 inch,then stared braking the trans lol its a never ending thing,the price you pay to go fast

 

That's true the faster you want to go, the more it costs.

 

"Speed costs money. How fast do you want to go?"

-old Hot Rodder's addage

 

A GM 12 bolt is stronger than a GM 10 bolt?
About how much HP can a 12 bolt withstand?
Considering the a girdle and welding has been done.

 

Plenty. There are a lot of very fast cars running 12-bolts. Probably around 800HP when properly prepared.