Advice for 3.70 geared 68
Thread Starter
Le Mans Master
Joined: Jan 2001
Posts: 6,938
Likes: 1
From: San Diego CA
Advice for 3.70 geared 68
I cruised the Vette this morning to the locksmith and at 80 MPH on I-8 East I was fast approaching 4000 RPM. Okay it has a M-21 4spd. close ratio and 3.70 gears. It eventually needs a clutch/ pressure plate/ throw-out bearing plus the drain plug is broken off flush with the case. All in all a tranny shop will charge $500 minumum for that work. Since I'm running too high on RPM's it seems that changing rear gears is not the answer as fixing the matching #'s tranny is so expensive and maybe I should be considering a Keisler 5spd. Plus if I kept the 4spd. had it fixed and switch to 3.06/7 gears would yield a crappy off-line launch. Even with nursing the clutch it runs like a raped ape once you get the RPM's up there. Let me know your thoughts.
David
David
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Re: Advice for 3.70 geared 68 (Double Aught)
run 65, higher gears,or 5speed????? i vote 5 speed
:withstupid:
:withstupid:
The 5-speed OVERDRIVE tranny was the best thing that I ever did to my C3 :yesnod: :yesnod:
[Modified by GrandSportC3, 12:02 AM 1/11/2004]
Racer
Joined: Dec 2003
Posts: 257
Likes: 0
From: Livermore CA
Re: Advice for 3.70 geared 68 (Cali,68,L-79)
How about a 6 speed???? If 5 is good isn't 6 better??? :party:
Keep the M-21 incase you ever sell your car at least the original trans can go with it. :yesnod:
Keep the M-21 incase you ever sell your car at least the original trans can go with it. :yesnod:
Melting Slicks
Joined: Mar 2000
Posts: 3,206
Likes: 0
From: WANTED: '68 rear valance with b/u light assemblies IM, e-mail, or PM me here. Thanks!
Re: Advice for 3.70 geared 68 (JJMURFS)
How about a 6 speed???? If 5 is good isn't 6 better??? :party:
Keep the M-21 incase you ever sell your car at least the original trans can go with it. :yesnod:
Keep the M-21 incase you ever sell your car at least the original trans can go with it. :yesnod:
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Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Re: Advice for 3.70 geared 68 (Cali,68,L-79)
:confused: Ya know I read about as many unhappy people with those Keisler things as I read about those that like them. It’s just that a close ratio with 3.70 gears is great set-up. Only draw back is higher rpm at fwy speeds. But consider how many miles a year are you going to be driving this car on the fwy? How much gas will you have save to pay for that new trans? I’ll bet you could build a new hi-po mill for what a new 5-speed cost to install - total package.
Can you fit taller tires? :chevy
Can you fit taller tires? :chevy
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
Re: Advice for 3.70 geared 68 (cardo0)
Go with the 5 speed. I have 3.70 gears with a M20. I have had my M20 out many times for various problems. You will still have a 30 year old tranny even if it is rebuilt. The close ratio trans was built for road racing to keep the rpms in a desireable torque range. The M20 was a better street transmission. I have not heard many complaints about anyone going to a 5 or 6 speed. Yes the cost is high but it makes driving the car a pleasure. I have a Tremec going in right now. Can't wait for a more civilized car.
Safety Car
Joined: Dec 1999
Posts: 4,148
Likes: 5
From: Roxbury NJ
Re: Advice for 3.70 geared 68 (Cali,68,L-79)
5 speed all the way! If you have to stay with a 4 speed on the street, the M20 is a much better than the M21, but they both suck in comparison to the 5/6 speed conversions.
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Re: Advice for 3.70 geared 68 (Cali,68,L-79)
Go 5 speed, one other bonus going 5 speed is you increase your MPT (Miles Per Tank) so you don't have to stop as often to fill up esp on longer trips. I was going to go EFI before 5 speed but I have changed my mind and am going to go with a 5 speed first.
[Modified by Fevre, 10:24 AM 1/11/2004]
[Modified by Fevre, 10:24 AM 1/11/2004]
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
Re: Advice for 3.70 geared 68 (Fevre)
Even I will vote for a 5 spd! :lol: Just make sure 5th gear is an overdrive! :) (The Richmond 5spd is a 1:1 5th gear)
M20 or M21, both have a 1:1 4th gear. Even with my 3.36 rear gear I don't feel comfortable at 80 - revs are too high and noise gets obtrusive. 65/70 is max comfortable speed and the trucks pass me. :( But I do very little highway driving (roundtrip to Carlisle once a year).
One thing I don't follow - When you weigh the alternative costs, most of the work you need is not the transmission. Only the trans oil fill plug is a trans issue. MJ
[Modified by MNJack, 10:34 AM 1/11/2004]
M20 or M21, both have a 1:1 4th gear. Even with my 3.36 rear gear I don't feel comfortable at 80 - revs are too high and noise gets obtrusive. 65/70 is max comfortable speed and the trucks pass me. :( But I do very little highway driving (roundtrip to Carlisle once a year).
One thing I don't follow - When you weigh the alternative costs, most of the work you need is not the transmission. Only the trans oil fill plug is a trans issue. MJ
[Modified by MNJack, 10:34 AM 1/11/2004]
Thread Starter
Le Mans Master
Joined: Jan 2001
Posts: 6,938
Likes: 1
From: San Diego CA
Re: Advice for 3.70 geared 68 (MNJack)
Even I will vote for a 5 spd! :lol: Just make sure 5th gear is an overdrive! :) (The Richmond 5spd is a 1:1 5th gear)
M20 or M21, both have a 1:1 4th gear. Even with my 3.36 rear gear I don't feel comfortable at 80 - revs are too high and noise gets obtrusive. 65/70 is max comfortable speed and the trucks pass me. :( But I do very little highway driving (roundtrip to Carlisle once a year).
One thing I don't follow - When you weigh the alternative costs, most of the work you need is not the transmission. Only the trans oil fill plug is a trans issue. MJ
[Modified by MNJack, 10:34 AM 1/11/2004]
M20 or M21, both have a 1:1 4th gear. Even with my 3.36 rear gear I don't feel comfortable at 80 - revs are too high and noise gets obtrusive. 65/70 is max comfortable speed and the trucks pass me. :( But I do very little highway driving (roundtrip to Carlisle once a year).
One thing I don't follow - When you weigh the alternative costs, most of the work you need is not the transmission. Only the trans oil fill plug is a trans issue. MJ
[Modified by MNJack, 10:34 AM 1/11/2004]
Jack just a little confused don't you consider clutch/ pressure plate/ throw out bearing trans issues?
:confused:
I mean if I get a Keisler it will come with all that new correct?
Safety Car
Joined: Dec 1999
Posts: 4,148
Likes: 5
From: Roxbury NJ
Re: Advice for 3.70 geared 68 (Cali,68,L-79)
Jack just a little confused don't you consider clutch/ pressure plate/ throw out bearing trans issues?
:confused:
I mean if I get a Keisler it will come with all that new correct?
:confused:
I mean if I get a Keisler it will come with all that new correct?
Drifting
Joined: May 2003
Posts: 1,634
Likes: 2
From: Melbourne, Victoria, Australia, the World
Re: Advice for 3.70 geared 68 (Flareside)
I have the 3.7 rear and Tremec 3550 behind a big block.
The 5 speed is absolutely the best thing to do. Apart from the more relaxed cruising at speed and the better economy, first is lower than the M20 or M21.
Gets off the line like it has 4.11s!
BTW, I know no one with a Vette cares about economy!
:cheers:
The 5 speed is absolutely the best thing to do. Apart from the more relaxed cruising at speed and the better economy, first is lower than the M20 or M21.
Gets off the line like it has 4.11s!
BTW, I know no one with a Vette cares about economy!
:cheers:
