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sure grip ratio
https://www.slantsix.org/forum/viewtopic.php?t=9502
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Author:  busboy [ Sun Jun 06, 2004 4:11 pm ]
Post subject:  sure grip ratio

Just picked up a 7 1/4 rear, sign said it is out of a 67' cuda. Ring gear shows very little wear and the lash feels good. It is a sure grip stamped 12 27 66B. The ratio stamp is not clear, looks to me like 2.93 but I never heard of that one. Has anyone heard of that ratio? The garage "spin and count" method confirms just shy of three revolutions, but I never heard of that one.

Author:  DusterIdiot [ Sun Jun 06, 2004 4:42 pm ]
Post subject:  middle...

'economy' rears could have 2.93/4 ratios... some duster 360's could be had with sure grip 2.94's....good traction for road handling and mileage....
(much nicer than 2.76's any day...)


If you have an automatic she'll be a good road gear, if you're draggin' you need 3.XX....

-D.Idiot

Author:  busboy [ Sun Jun 06, 2004 6:55 pm ]
Post subject: 

It is going behind a 225/904 drivetrain that currently has 2.76's and no draggin' in the plans so it should work well. Thanks DI. Any idea what horsepower a sure grip 7 1/4 will handle?

Author:  DusterIdiot [ Sun Jun 06, 2004 7:18 pm ]
Post subject:  Dunno, but...

there are a couple guys that are using the 7 1/4 SG...I'm sure it'll take whatever you're going to dish out...not like you're putting a 400 ft/lbs of torque small block in front of it....


-D.Idiot

Author:  sixinthehead [ Mon Jun 07, 2004 4:56 am ]
Post subject: 

Using a SG unit eliminates the weakest link in a 7 1/4; the spiders. However, it's still a tiny differential with itty-bitty splines, axles, etc. The key to letting it live is avoiding really sticky tires and high shock loads (popping the clutch at 5000 rpm). Use the tires as the fuse; if they spin, things don't break as much.
It should live a long time behind a slant with proper care and sane driving habits.

Author:  Charrlie_S [ Mon Jun 07, 2004 6:08 am ]
Post subject: 

I agree about avoiding shock loads on the 7 1/4 rear. But I ran slicks on the same rear from 1974 till last year, when I changed to a 8 3/4. My cars weighed from 2500 lbs to 3200 lbs, drag race and street use. It is a 3.91 sure grip unit, and was in cars, that were stock, had turbo's, nitrous, and have run as quick as 13.3 at 104 mph with turbo and 13.4 at 97 on nitrous. But with 1.79, 60 ft times, I thought that was asking a little to much from the rear, but it never broke. With an auto, no problem, but I would not run a stick, and hammer it.

Author:  sixinthehead [ Mon Jun 07, 2004 7:00 am ]
Post subject: 

I have over 150,000 mi on my 7 1/4 behind a built 318 in one of my 65s, and it's still going strong. Using an automatic helps cushion the drivetrain, unless you're using a transbrake :shock: .
Charrlie is a hero at getting a quart from a pint pot; 13s with 170 ci and 7 1/4 rears is awesome 8) in any book.

Author:  hornet [ Mon Jun 07, 2004 8:29 pm ]
Post subject:  info reply

no i only typed 10% the rest was on a floppy that a buddy left here i hope it was useful info

Author:  DusterIdiot [ Mon Jun 07, 2004 9:16 pm ]
Post subject:  What the?!?!?

How did we get from talking about the 7 1/4" to the 8 3/4" ?...that's like lemons and Pummelos....

Good info though, if you didn't write that article make sure you mark down who the author was so we can thank/credit him/her if necessary...

Let's get back to axle assemblies that only cost $150 and weigh less....

-D.Idiot

BTW, we had a local swap meet last week end and a '742' 3.23 with SG 'chunk' was priced at $500...you provide the rest of the assembly...

Author:  ShivaDart [ Mon Jun 07, 2004 9:45 pm ]
Post subject: 

Hornet, please tell me that's a copy/paste. I feel very sorry for you if you had to type all that information out :shock: . It is good information though.

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