I have the 7 1/4 rear with plans of rebuilding the 8 1/4 I have with the LSD and 3.23 gears. The cost to complete this including the new wheels and tires is a little more than I like to spend right now. (next year would include the rear and new trans)
I'd like to take it to the track when the new motor is installed, but my friend that has lots of track time says to not even think about taking it without the rear upgrade. He says the chance to breaking the rear is very high and it will likely send me into the barrier. (he has seen it many times)
Now I would likely agree if I where go to run wide drag slicks, but I plan to run a S rated BFG 215-70-14. Now I know my times will suffer but I'd like to run down the track. (never been) Would you say that running this thin tire would "protect" the rear from blowing? With an open diff 7 1/4 I would think the load would be limited by the tire spinning. Are the tracks alot more sticky than a dry dust free street road?

_________________
67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

Charrlie runs a 7 1/4 behind his nitrous fed car running in the 13s.

_________________
Rob

I’m Mater
The Kentucky Poser

Its also got a LSD

_________________
67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

I swaped it out for an 8 3/4. I figured I was pushing that little 7 1/4 a bit too much. But it did good for over 20 years. And yes, it is a sure grip (3.91}. Makes a world of difference.

I also have a 5.13 SG rear, and have another SG on the shelf, and a NOS set of 4.56 gears.

_________________
Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

The odds of breaking a rear and crashing into the wall are incredibly slim. With an open rear all you are going to do is spin one tire anyway. If you break it chances are it won't get off the starting line anyway.

Does your buddy think you are building a Hemi Super Stocker or something?

_________________
Official Cookie and Mater Tormentor.

I side with Slantzilla. Most likely, the worst that would happen, is you don't drive the car home.

_________________
Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

As long as the rear is in good shape (no noise, proper backlash and bearing preload, crosspin tight in carrier), I'd say you will be alright to try it out a few times. I ran one (3.23 open) for years behind a mild 318 with 235/60-14 tires and never broke it on the street, but dragstrip use qualifies as abuse and it won't last too long.
Dragstrips are generally "stickier" than the street (especially if they slather on the VHT), and the shape of the contact patch on a tall tire could give you more grip than you might expect. You might stress the rear more during a very hard 1-2 shift than off the line.

_________________
O==\=/==O

"A mechanic is Somebody."
- Jim Preston

Thats the point he said they where hitting the wall.

_________________
67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

How you leave the line has a bit to do with stress on the rear as well. If you get wheel hop it is harder on the rear because of the repeated shock loads. It will ruin your times too.

A car with an open rear will not turn when it breaks. Cars with spools do that.

_________________
Official Cookie and Mater Tormentor.

Did someone say Hemi Super Stocker?

Don't worry, you won't hit the wall. Odds are the spider gears will break.
The thing I would worry about is, if the rear breaks, you really need to pull the trans and check the sprag for damage. If you don't and it is damaged, the next time you rev it up, expect trans parts to possibly come thru the floor. Just change to gear oil in the 8.25 rear, put it in and run it with the open 2.94 gear. Change the gear and carrier latter when you have time.

_________________
Slant Cecil

The 8 1/4 I got dosn't turn smoothly (by hand). I opened it up and there was a little water mixed in with the gear oil. The gears look fine but I can't see the bearing with out disesembly. Do you think the bearings got a little rusted during storage? If I run the rear like this can I ruin the rear to the point that it will need more than new gears and bearings? If not, thats what I'll likely do. (install it)

_________________
67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir