Rear end gears?

**Wicked96Z** · 08-12-2005, 04:28 PM

I'm looking to change the gears in my 96 Z-28. Going from 3.42 to 3.73. Other than speedo being off, any driveability problems or other sensors affected? It's a six speed manual. I would rather find out now if there are any other changes i need to make at the same time i do my gears instead of finding out the hard way. Thanks in advance.
~Lee

**Hurley711** · 08-12-2005, 04:45 PM

I'd check with other members about jumping to 3.73's from 3.42's. I'm not sure you are going to notice a real big diff.

**BIG D's SS** · 08-12-2005, 05:16 PM

I have talked to several people about going to 3.73's and they said that there wasn't a big enough difference to notice. That is why I went with the 4.10's. Everyone I have talked to said there is no problems except the speedometer which you already know about. I called a place here in Atlanta and they said about $50 to recalibrate it.

**Ric** · 08-13-2005, 05:55 AM

There's differing schools of thought when it comes to gear selection. On one hand, the 4.10s will get you out of the hole quicker than the 3.73s. But, when you're near the finish line, the 4.10s will cause you to either A). over-rev the engine, or B). have to lose time upshifting into a gear that supplies less torque to the ground. This is all assuming near stock powerband, of course. Either gear is perfectly fine for the street. I just wish like crazy that somebody'd start making 3.90s for a 7.5" 10-bolt.

Other changes???

Welp, that 10-bolt rear won't be around too much longer if you make much more than stock power. Not to go off on a different tangent, but maintenance is an issue of concern with it, too. The axle bearings ride directly on the axleshaft, which means the shaft will eventually wear out and need replaced.

Now, a Ford 9" uses bearings that have their own hardened races, and are pressed onto the axleshaft, which eliminates the need for C-clips. Bearing goes bad, just press off the old'un, press on the new'un(Plus, you don't have to pop the diff cover to pull the shaft.), simple as that.

Oh, I forgot to mention that a 9" is WAY stronger than a 10-bolt.

**Killer_bluebird** · 08-24-2005, 09:56 PM

There is a company that is making a Ford 8.8 for Fbodies at a decent price too. So it is a good low buck option if you don't need something caplable of handling 600 hp+. Plus is slightly lighter than a 9".

rays00ramair · 09-15-2005, 06:36 AM

hey killer any idea who makes that retrofit 8.8?i was pricing out a 12 bolt and a 9 and 1900-2500 is ridiculous.i mean come on it dont cost that much to build them.

**Eugenio_SS** · 09-15-2005, 08:30 PM

Originally Posted by rays00ramair

hey killer any idea who makes that retrofit 8.8?i was pricing out a 12 bolt and a 9 and 1900-2500 is ridiculous.i mean come on it dont cost that much to build them.

http://www.extremechassis.com/
considered it for awhile.... ended up w/ a 9"

rays00ramair · 09-17-2005, 07:10 PM

thanks for the link but they are real close to mosers 12 bolt.ive seen one of these conversions at the track this weekend and am going with a 12 bolt and 3.90s inside.when the wife allows of course.btw what did u do to fit the 315 out back?gonna have the rims widened to 11 by stockton wheel and use 315 35 17 out backany advice?

Rhino21149 · 09-18-2005, 06:24 AM

I went to 3.73's when I put a Strange rear in in my 98 Z28 as it was a good compromise between more off the line torque and a higher speed without overreving at the top end. It made a very noticeable difference in torque and feel off the line and around town (the car is a strip/street car).

My reasoning was the following: The car has a 408 FE engine now and revs safely to 7K+ RPM (AFR heads, beehive springs, shaft rockers. The engine red line which is 16% higher than stock. The gear change are a 10% change in ratio which leaves 6% more at the top end in 4th before I have to shift, which ought to be just about right at the end of the quarter. 4.10s would have given me more off the line, but forced another shift before the end of the quarter.

Rhino21149 · 09-18-2005, 06:32 AM

On a different thought, I am thinking of going the other way on my vette. The reason is that it has a C5R and Procharger now, even with 345 drag radials and a limited slip differential, the car is ALLwheelspin in 1st gear and mostly in second: it breaks traction on power alone: no need to drop the clutch -- when running on the street in second, just mash the throttle at 3K RPM and the rear wheels instantly start spinning on anything but a perfect, perfect surface.

The rev limiter on the 427 is set at 6250 (I have too much money in the engin to push for higher RPM, and the power peak is low) this is 250 RPM lower than stock LS6-- with the street SC cam and tuning for low eng torque, it produces 595 RWHP at 5500-6300 RPM, doesn't need to rev. Means top speeds in gears are lower, too . . .

If I went to 3.23 gears: they would lessen torque in 1st and second but not really hurt acceleration since its all wheellspin anyway, and extend my top end speeds in gears: right now it is ride the rev limiter or shift to fifth right at the end of the quarter..