Picking a Rear End

[Steve Starnes]

I have a 88 Mustang with a 331 stroker turning 470 HP. It has a Tremec 3550 5 speed. (1st 3.27, 2nd 1.98, 3rd 1.34, 4th 1.00, 5th 0.68. What rear end should I install to get the best 1/8 mile times?

Thanks
Steve

[Rory McNeil]

What tire diameter, clutch type and car weight? A few years ago, I swapped out the Stock Elminator 302 out of my 85 Mustang hatchback, with my 331 bracket SBF (485 HP at flywheel), retaining the Jerico 4 speed (3.19. 3.00, 1.32, 1.00) and McLeod Soft Lok clutch, car weighed 3050 lbs, running 9 x 29 1/2 M/T slicks and 4.88 gears in the 8.8, I would shift at 6800, and go thru the traps at 7200, at 128 MPH. I have never really raced much 1/8th mile, but my car would go 102-103 MPH in the 1/8th, so I would ASSume that you would want to gear it steeper than my car, unless you were running shorter tires. On my car at least, I found the 5.14 gears for a 8.8 to be much weaker than the 4.88s. I broke 2 5.14 gear sets with the Stocker engine, running mid-low 12s at 107 MPH, but the 4.88s looked fine after 2 years of running 2 seconds quicker and 60 footing .25 quicker than the Stocker combo.

[4speedracer]

I race a 4speed now 5speed fox body when I had a 8.8 it broke at axle tube to center section my suggestion sell 8.8 and put money towards 9 inch stronger more gear selection. 8.8 had welded tubes and bracing with stock type suspension was trying to prevent it from breaking. 8.8 with auto ok, stick and sticky tires not so good will work for awhile. But when i ran a 8.8 in the 1/8 ran a 5.14 with 3.08 1st gear jerico best i can remember went through light at about 6-6500 shifting about same rpm. 28x10.5 tire

[Steve Starnes]

Thanks for the sharing your experience and knowledge

[SSGT Mustang]

I've put plenty of power through and 8.8 and never had a problem. It's a good differential. Basically a Ford copy of the 12 bolt GM, which has stood up to some serious abuse over the years.

Straighten the tubes, weld them to the center section and get a bracing kit from teamz.

http://www.teamzmotorsports.net/prod...zm-8.8-cbk.htm

Put better ends on them like a big Ford or symmetrical and 35 spline axles and the thing will hold up to a lot of power.

[SSGT Mustang]

Originally Posted by Rory McNeil

What tire diameter, clutch type and car weight? A few years ago, I swapped out the Stock Elminator 302 out of my 85 Mustang hatchback, with my 331 bracket SBF (485 HP at flywheel), retaining the Jerico 4 speed (3.19. 3.00, 1.32, 1.00) and McLeod Soft Lok clutch, car weighed 3050 lbs, running 9 x 29 1/2 M/T slicks and 4.88 gears in the 8.8, I would shift at 6800, and go thru the traps at 7200, at 128 MPH. I have never really raced much 1/8th mile, but my car would go 102-103 MPH in the 1/8th, so I would ASSume that you would want to gear it steeper than my car, unless you were running shorter tires. On my car at least, I found the 5.14 gears for a 8.8 to be much weaker than the 4.88s. I broke 2 5.14 gear sets with the Stocker engine, running mid-low 12s at 107 MPH, but the 4.88s looked fine after 2 years of running 2 seconds quicker and 60 footing .25 quicker than the Stocker combo.

Let me guess. You cracked the wide end of every pinion tooth on the 5.14s.

Cryo and rem polish helps a lot. Also, the pattern is key. The depth number marked on the pinion is almost worthless. Talk to Indy gear. He's a wealth of information and can get you the gears cryo's and rem'd for a very reasonable price.

With the smaller pinion, you need to watch the pattern not only on the ring but on the pinion itself. Try to get the pattern to favor the small end of the pinion rather than the wide end. It'll spread the load better over the thicker material rather than the thinnest part of the tooth.

I had 5.14s in a nine second car leaving on the transbrake and the gears held up. Give it a shot if you need more gear in your stocker.