mike_c

iTrader: (13)

I recently found a good deal on a freshly rebuilt 9 bolt rear with a 4.11 ratio. I also have a T5 that I'm about to swap in. It has the following ratios:

1st: 2.95
2nd: 1.94
3rd: 1.34
4th: 1
5th: .73

My car currently has a 700R4 and a 3.27 rear. Do you think the T5 combined with the 4.11 would be too much gear for my car? Does anyone else run this setup?

I also put these charts together using an RPM/MPH calculator I found after a quick Google search; Currently, at 65 mph my car turns about 2000 RPMs. After looking at these numbers, it will be doing about 65 MPH at 2500 RPMs. Does this seem right? I dont do much highway driving, but I can certainly deal with a 5-600 RPM difference at 65 MPH.

1st Gear
(RPM) Speed (MPH)
5500 RPM 35.14 MPH
5000 RPM 31.95 MPH
4500 RPM 28.75 MPH
4000 RPM 25.56 MPH
3500 RPM 22.36 MPH
3000 RPM 19.17 MPH
2500 RPM 15.97 MPH
2000 RPM 12.78 MPH
1500 RPM 9.58 MPH
1000 RPM 6.39 MPH

2nd Gear
(RPM) Speed (MPH)
5500 RPM 53.44 MPH
5000 RPM 48.58 MPH
4500 RPM 43.72 MPH
4000 RPM 38.86 MPH
3500 RPM 34.00 MPH
3000 RPM 29.15 MPH
2500 RPM 24.29 MPH
2000 RPM 19.43 MPH
1500 RPM 14.57 MPH
1000 RPM 9.72 MPH

3rd Gear
(RPM) Speed (MPH)
5500 RPM 77.36 MPH
5000 RPM 70.33 MPH
4500 RPM 63.30 MPH
4000 RPM 56.26 MPH
3500 RPM 49.23 MPH
3000 RPM 42.20 MPH
2500 RPM 35.17 MPH
2000 RPM 28.13 MPH
1500 RPM 21.10 MPH
1000 RPM 14.07 MPH

4th Gear
(RPM) Speed (MPH)
5500 RPM 103.67 MPH
5000 RPM 94.24 MPH
4500 RPM 84.82 MPH
4000 RPM 75.39 MPH
3500 RPM 65.97 MPH
3000 RPM 56.55 MPH
2500 RPM 47.12 MPH
2000 RPM 37.70 MPH
1500 RPM 28.27 MPH
1000 RPM 18.85 MPH

5th Gear
(RPM) Speed (MPH)
5500 RPM 142.01 MPH
5000 RPM 129.10 MPH
4500 RPM 116.19 MPH
4000 RPM 103.28 MPH
3500 RPM 90.37 MPH
3000 RPM 77.46 MPH
2500 RPM 64.55 MPH
2000 RPM 51.64 MPH
1500 RPM 38.73 MPH
1000 RPM 25.82 MPH

Thanks for your help and reading this long post.

crowbarmaster

I would have to say yes, a friend of mine had a 4.11 with a T-5 with a 355 and said first gear was REALLY short. I would probably keep the 700r4 with a 4.11 or get a TH-350, that shouldn't have any issues holding power.

sofakingdom

iTrader: (1)

Before getting all worked up over that, MAKE SURE the gears are REALLY 4.11.

Reason I say that is, I know of NO 4.11s that were ever available for that rear. There may have been of course, and I just don't know about it; but I'm skeptical. And not inclined to believe it without seeing it WITH MY OWN EYES, besides.

Physically observe the gears. Count the teeth. 4.11 is 9 on the pinion and 37 on the ring. And of course, count the bolt HOLES on the cover; somebody might just have a 10-bolt with one bolt left out, for all you know. Don't get all excited until you verify the facts by some means other than used-car-salesman "tell em what they wanna hear" monkey-spank.

And don't forget, you have a 89, which if it has discs (it should, that car came with them at least) are the good ones. VERY FEW 9-bolts have those. Most of them have the crappy Saginaw ones they used from 88 back, from 85 to 88 on the 9-bolt. If it has the garbage ones, that'll be a bit of extra work swapping them over, at the very least.

That said, I agree, 4.11 is too much gear for a T-5, especially with a TPI motor with their very poor upper RPM characteristics (like, no power past about 4500). However 4.11 is about perfect for a car with a T-56 and a better motor with some rev capability.

mike_c

iTrader: (13)

Thanks for the input guys. sofa, the rear is for sale in the classifieds here, I haven't seen pictures of it yet to verify if it's actually a 9 bolt, I still haven't heard back from the guy, but I have no reason to believe that it's not. 9bolt.com has a 4.11 ring gear listed on their site, so it would seem that they do exist. I know, I know, seeing is believing... And the rear is from an '89 and it has the PBR discs like mine does.

That said, I think I'm going to pass on it.

89fbirdformula

put an HSR on the motor, that rearend in the car...and have FUN.

dont speedshift/powershift the T5...

my car was fun with 3.45s, would have been much better with a 4.10 gear/28" tire.

FSTFBDY

iTrader: (33)

That rear end f/s is from Justin. Yes its a 9bolt. yes its rebuilt with the best parts you can get for a 9bolt. 4.11's, new posi cones, etc.. Just like the add says.

4.11's and a T5 would be a hell of a fun street/light to light car. TPI doesnt rev past 5k anyways so have fun with everything under the curve.

We put 4.11's in a buddys TA with a 355 and 700r4 and it was a fun car from a stop ,etc

That being said. if you sepnd the $800 its worth every penny.

Justin89Formy

iTrader: (26)

yeah thats my rear. It definitely has 4.11 gears. I've bought all the parts myself, seen them myself, and watched them installed by my good friend who is a mechanic. Its all legit. I have more than my asking price into it. Its a stout rear for sure. And with VERY low miles. Sofakingdom...I tend to think your username is accurate Oh, and FYI I forgot to add that the axle tubes have been welded for extra strength

sofakingdom

iTrader: (1)

Well, like I said, I haven't seen it "all", and don't claim to; just, I'm REAL skeptical when somebody posts up here about "somebody is trying to sell me a ...." and it's too good to be true. I advise people to be ABSOLUTELY SURE before biting off on some sucker line as all too often happens. OTOH, if it's real and verified and and comes from a reliable source, then that's a different matter.

Yeah my userID is pretty accurate actually... I have a wife and just-past-teenage kids so I get reminded of just how much THAT I am, many times a day.

Tony89GTA

iTrader: (7)

If your planning on keeping the TPI intake then I think it's to much gear for it.

89fbirdformula

i agree, 3.45 is max id ever go for true TPI intake..

however, hsr/lt1/minram...it would be FUN with 4.11s!

MaxpowerTA

well I have 4:11's and A T5 in my 92 vert with TPI and I think it's a hoot!

mike_c

iTrader: (13)

Rather than start a whole new thread, I figured I'd just update this one. Like the new title says, would a 3.70 rear gear be a better option? I'd like to go with a shorter ratio, but upping to a 3.45 doesn't seem like it would be worth the hassle.

Also, my "new" T5 is getting a rebuild in the next few months using G-force parts, and I have the option of a .59, .63, or a .75 5th gear ratio. Which ratio would be best with a 3.70 rear? I don't do too much highway driving, but I'd still like to have a decent overdrive for when I do. Thanks for any advice

jmd

iTrader: (4)

You might see your questions addressed here.

https://www.thirdgen.org/forums/tran...needed-t5.html

(I LOVE low highway rpm. I'd never do .7x fifth in a T5 for myself.
Are you rebuilding your box yourself?)

calebzman

iTrader: (3)

I'd go with the lowest overdrive gear possible. I have the .5 overdrive with the T56 and like it much better than when I was running the .63 ratio with the T5. I don't agree with the person who said 3.45 max for tpi. Higher gears will accelerate faster by getting to the powerband quicker. The only drawback being high cruising rpms on the highway. But with the low overdrive gear, it won't matter if you choose 3.70 or 4.11 rear gears.

mike_c

iTrader: (13)

Thanks guys, and jmd, I'm going to try and rebuild it myself. I've never done anything like that before, but if I start tearing it down and feel like I can't do it, I'll have it done by a pro.