Power limits of the 7 1/4 suregrip?

[scottymizt]

This has probably been answered someplace on here but i couldn't find it searching or just looking at certain topics. What is the limit of the 7 1/4 s/g? Mine is the stock one in my 65 273 and it needs some attention. I get a vibration at high speeds and under normal cruising, if i give it gas it quits and if i let off completely it quits as well. There is no play in the pinion shaft or axles but i did notice that the pinion has play where the shaft turns a bit but the wheels dont. I am going to look into the case tonight but just some quick testing i found that the carrier is moving when the wheels aren't during this testing. This is leading me to the sure grip having a problem. Basically i plan to get more power out of the old girl(just like most of us) and figure why fix this diff if i need a bigger later?

 

[rumblefish360]

I'd becareful with that rear, even more so on that description.
Replace it? Yes, agreed.
I would look into a 8-1/4 or the 8-3/4. The later is more expensive. The 1/4 rear can take a decent amount of power. If you plan on more than 400 "race" hp, I'd go up in size to the 3/4. Otherwise, you'll be fine.
The A body 3/4 rear is mostly found with a small bolt pattern. (5 on a 4 circle) Which makes rim choices limited or custom ordered.
The 1/4 rear is a (Mostly allways I believe) a 5 on a 4-1/2 circle. Which takes rim choices into a bigger book of choices.
Food for thought, I scored a 8-1/4 with a suregrip and 3.21's for $200. I don't know how that compares to the rest of you, but a clean up and bolt in was just fine by me. There also not exactly easy to come by around here.

 

[Jim Lusk]

I can tell you that a 7-1/4 cannot reliably handle the power of a stock 273 four barrel with a four speed (don't ask me how I know).

 

[project74]

I too scored an 8 1/4, complete minus brake hardware with a new 3.55 ring and pinion and new suregrip for $200. Them deals is out there.

 

[scottymizt]

Maybe i can get one from bill, i have yet to hear from him. I didn't know it but he only lives 20 mins from me He told me he has a ton of parts hopefully he has what i need.

 

[Charrlie_S]

The 7 1/4 rear is a lot stronger, then most people think, if it is in good condition. Just remember, by this time it probably has many-many miles on it, and is well worn. A 7 1/4 rear needs a sure grip to handle a performance engine. The early, clutch type SG rears, had 4 spider gears, while the open rears and the later "cone" SG's had 2 spiders. I would have no problem runing a 7 1/4 SG with a stock or "warm" 273 or 318, with a auto trans, it the rear was in good condition. I would not use it with a stick, it will not live with the shock loads of hammering gears. I ran a 3.91 SG 7 1/4 in my 66 Cuda for many years, before I found a "A" body 8 3/4, and swapped them out. My Cuda weighs 3250, has slicks, and turns low 13's at 97 mph in the quarter, with a 1.78 60 foot time. It is also a limited street driver.

PS" if you would want to sell the sure grip unit from the 7 1/4, please contact me. flturbo6@aol.com

 

[scottymizt]

I have a 4sp in my cuda and it has held ok but it does have alot of miles on it. I wouldnt even worry about it if i didn't get noise from the rear. Is there something that i should look for in the carrier that would make it vibrate like it is?

 

[scottymizt]

Also what is it that can't handle the power? what is the weak spot in the 7 1/4 rears?

 

[388dart]

Chrysler was ahead of there time with a 7 1/4" - it would have went well in a "Smart Car" M2CsW. Go 8 1/4 - there is lots of them.