Autogear with 3.08 rear - Chevelle Tech
Transmission & Driveline Transmissions and Differentials

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post #1 of 27 (permalink) Old Jul 9th, 17, 8:14 PM Thread Starter
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Pat
 
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Autogear with 3.08 rear

This fall I am going to get one of Jody's "Z" transmissions with the lower first gear. I have been talking to Jody, who is great to deal with! and we are discussing some options. My 70 currently has 3.31 gears. I took it on the highway today and just feel to really enjoy this car on the highway I need less gear or an OD transmission. I would go with a Legend but I just cant afford it. So I am looking at a 3.08 gear.


I really don't want the 3.08 but should make it more highway friendly and Jody's transmission should still give me the hole shot power I am lacking with the M-20 and 3.31 combo.


Anyone hearing running the 3.08 with one of these trannys? are you happy with it?
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post #2 of 27 (permalink) Old Jul 9th, 17, 8:33 PM
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Re: Autogear with 3.08 rear

pat - what size rear wheels/tires are you running?
tire diameter increase/decrease will affect the "overall" gear ratio
what engine are you working with in your drivetrain...
the change in rear axle from 3.31 to 3.08 will make about 250-300rpm less
change in tire diameter could be 50-200 rpm plus/minus...

68-Malibu 427bbc/t4oo/3.73-12bolt/pro charger f1-r
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post #3 of 27 (permalink) Old Jul 9th, 17, 9:28 PM Thread Starter
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Re: Autogear with 3.08 rear

Vince,

285/40/18's.

I have a 454 in the 530HP/550 TQ range at the crank power.

When driving down the highway with 3.31 it is just turning a little more than I would like to be enjoyable.


Another option is a TKO 500/600 I assume, but was hoping to get one of Jody's transmissions in my car.

Pat
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post #4 of 27 (permalink) Old Jul 9th, 17, 9:49 PM
blm
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Re: Autogear with 3.08 rear

Pat, Here is a thread from a few months ago on this very subject.
https://www.chevelles.com/forums/33-t...nal-drive.html

I could talk at length on this. Have considered the same for a while. I ultimately decided to go with a Legend. If i were going to go with a 22Z or 23Z I would have definately gone with the 3:08s. Thing is once one changes rear gears they are not that far $ from the Legend. I definately decided against the Tremec. Tunnel mods and other issues are not for me. The big thing that the 22 or 23 trans have going for them is being able to reuse almost all of ones current drivetrain parts.
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post #5 of 27 (permalink) Old Jul 9th, 17, 10:04 PM Thread Starter
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Re: Autogear with 3.08 rear

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Originally Posted by blm View Post
Pat, Here is a thread from a few months ago on this very subject.
https://www.chevelles.com/forums/33-t...nal-drive.html

I could talk at length on this. Have considered the same for a while. I ultimately decided to go with a Legend. If i were going to go with a 22Z or 23Z I would have definately gone with the 3:08s. Thing is once one changes rear gears they are not that far $ from the Legend. I definately decided against the Tremec. Tunnel mods and other issues are not for me. The big thing that the 22 or 23 trans have going for them is being able to reuse almost all of ones current drivetrain parts.

Hey Brad,


I could not agree more about the Tremec, I want to deal with Jody so will figure out a way. I would like to do a Legend, but it may be a year until I could get one and really don't want to wait that long and just don't know if I can come with that much coin.


Will have to see what I can come up with.


Pat
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post #6 of 27 (permalink) Old Jul 9th, 17, 10:23 PM
blm
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Re: Autogear with 3.08 rear

If you go with the Z trans and a 3:08 rear end you will only see a 200-300 rpm drop over your current 3:31 rear set up. My suggestion is to go out on a quiet highway and drive your car at 70mph. Record that rpm. Then drive at 200-300 rpm lower than the previous rpm and see what that is like. I found it wasnt so much the rpm but the exhaust report.
In my case the Legend will drop my highway rpm by 1K. Plus I can keep my 3:73 rear gears.
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post #7 of 27 (permalink) Old Jul 9th, 17, 10:58 PM
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Re: Autogear with 3.08 rear

Just do the tremec. It's not a hard install at all. It's mostly internet hype about it. Mine went very smooth. Cut the hole, move the crossmember back, drill 2 new holes. Make a patch from plain sheetmetal, weld it in. I found a junkyard driveshaft the right length. Done. It was that easy.

Just the 3.08 isn't going to cut it at modern highway speeds. Mine has 3.08 and 26" tires. Speed limit on the highways here is 70-75, so everyone is driving 80-85. That equaled sitting in the right lane getting passed. Now with the TKO 600 and 3.08 I am doing 80-85 in the fast lane with all the modern cars. Now we take the Chevelle out of state on long trips all the time and don't worry about it. It's well worth it.
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post #8 of 27 (permalink) Old Jul 9th, 17, 11:11 PM
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Re: Autogear with 3.08 rear

Tom, No disrespect but not everyone wants to modify their trans tunnel. I understand you own a 66 four door car. If that what is had I probably wouldnt think twice about hacking the trans tunnel. But some people more sought after cars where cutting the tunnel just isnt something they would consider. Hope you can understand that.
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post #9 of 27 (permalink) Old Jul 9th, 17, 11:13 PM Thread Starter
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Re: Autogear with 3.08 rear

I agree and overdrive is probably the way to go.
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post #10 of 27 (permalink) Old Jul 9th, 17, 11:54 PM
T_R
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Re: Autogear with 3.08 rear

Quote:
Originally Posted by blm View Post
Tom, No disrespect but not everyone wants to modify their trans tunnel. I understand you own a 66 four door car. If that what is had I probably wouldnt think twice about hacking the trans tunnel. But some people more sought after cars where cutting the tunnel just isnt something they would consider. Hope you can understand that.
Nope, I am going to get a nice 66 or 67 convertible eventually maybe even a 138 car. I will surely cut a hole and put the tremec in it. It makes the car useable on modern highways. You are a rolling roadblock without overdrive. It's just sheetmetal, who cares. I used to think I wouldn't cut a hole in a nice car, but I would now after having the tremec in the car for a few months. I couldn't live without it now. If you wanted to you could weld the cut part back in and metal finish both sides so nobody would ever know.
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post #11 of 27 (permalink) Old Jul 10th, 17, 12:15 AM
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Re: Autogear with 3.08 rear

Or one could acquire a Legend or Richmond overdrive transmissions which don't require tunnel mods.
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post #12 of 27 (permalink) Old Jul 10th, 17, 12:24 AM
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Re: Autogear with 3.08 rear

what is a legend?
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post #13 of 27 (permalink) Old Jul 10th, 17, 12:46 AM
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Re: Autogear with 3.08 rear

Quote:
Originally Posted by blm View Post
Or one could acquire a Legend or Richmond overdrive transmissions which don't require tunnel mods.

Or the McLeod 5-speed

Or the mega-strengthened
T-5 at LongShifters.com

To HELp with that Quasimodo Tremec trans tunnel
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post #14 of 27 (permalink) Old Jul 10th, 17, 1:15 AM
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Re: Autogear with 3.08 rear

Quote:
Originally Posted by gnicholson View Post
what is a legend?
Learn about Legend Gear & Transmission's LGT-700
used to be the keisler kits

68-Malibu 427bbc/t4oo/3.73-12bolt/pro charger f1-r
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post #15 of 27 (permalink) Old Jul 10th, 17, 3:44 AM
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Re: Autogear with 3.08 rear

ok ive dealt with kessler didnt know of the cgange
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