how fast on a 7.5

**SSDEUCE** · 08-02-2010, 04:41 PM

I know this is a dumb question but like to know how fast people have been on a 7.5 rear with or with out aftermarket pats

**devildogws6** · 08-02-2010, 05:07 PM

top speed? ive been up to 155, quarter mile 112, ummm thats all i can think of or and 145 on dyno, putting 397rwhp not sure about tq tho

**tatertot91** · 08-02-2010, 05:19 PM

I got a top speed of 150 and let off
Are you talking track times?

**shady milkman** · 08-02-2010, 05:41 PM

in a auto i wouldnt worry too much really. do work and you might be in the 11s with a stock 7.5...

**SSDEUCE** · 08-02-2010, 06:24 PM

yeah sorry acually talkin e.t.

**pewterz55** · 08-02-2010, 06:28 PM

weird i was thinkin about this today and was gonna post the same question (just out of curiosity)

**tatertot91** · 08-02-2010, 06:33 PM

Originally Posted by SSDEUCE

yeah sorry acually talkin e.t.

That was what i figured

**Firebirdjones** · 08-02-2010, 06:47 PM

I can tell you what I've seen, worked on, or driven.
In general it seems the 11's are the breaking point for most that have been lucky up to that point. Most of those are with an auto.

Close friend running a 175 shot on his 7.5 rear with 3.73 gears installed, on drag radials and going 1.55 60 foot times. This car had an automatic. He ran the car for 2 years before selling it, running 11.30's at 117 mph or so,,,,with 100,000 miles on the clock, the rear was still in one piece. I'll venture to say he ran 20-25 bottles through that car in that time period.

Another friend had a 6 speed, stock 7.5 with 4.10's, drag radials. Motor only, the car ran 11.60's and 70's at 119+ mph. Can't remember the 60 foot times. But we would air up the drag radials on purpose to induce some wheel spin, and try to save the rear. It would break about every 10 runs. Most of the time it was an axle. Until the night I was driving, it broke the pinion shifting into 3rd gear at about 70+ mph. Shoved the driveshaft forward and busted the tailhousing off the transmission, ruining that too. Sprayed the track down, including my back tires, which nearly put me in the wall.
That experience alone was enough to tell me to never tempt fate again with these whimpy 7.5's. That one turned out to be an expensive repair, and it could have been worse if I had wrecked the car too.

But most of the survival stories I see are with autos, some running in the 11's. But honestly I don't even like that idea either. It's really not worth it to me.

I've gone 12's with both of our 4th gens, one auto and one 6 speed, but did it on stock rubber. And I drove the 6 speed very easy out of the hole. I've broken these rears without sticky tires, so even stock rubber makes me cringe anymore. It's a crapshoot to put it in simple terms.

**SSDEUCE** · 08-02-2010, 06:56 PM

from what i've seen the higher the gear(lower the number) the longer the gears last due to the amount teeth on the pinion thinkin i'll keep my 3.42's and put some alloy axles in it whenever she breaks that i'll look into another but don't plan on anything but some nitto's she is my d.d.

**Firebirdjones** · 08-02-2010, 07:05 PM

You are right, and I'd stick with the stock 3.42's and call it done. I wouldn't bother with gear installs on the 7.5's.

I've only done gear installs on the 7.5's for close friends that realize the consequences. Most others that want gear installs on 7.5's I just turn away. Don't care to do it. With a 4.10 you only have 1.5 teeth of contact on the ring gear. It's a recipe for disaster.

My opinion, these 7.5 are a door stop. I wouldn't sink any more money in them than you absolutely have to, and just run it till it breaks if you wish.