question automatic to 4 speed
Thread Starter
Intermediate
Joined: Jul 2011
Posts: 45
Likes: 3
From: Cedar Rapids Iowa
question automatic to 4 speed
I have a 1980 L48 3 speed automatic and planning on putting in a 4 speed. Can anyone tell me which ones would be a direct fit without any modifications, Thanks
Gary
Gary
Race Director
Joined: Aug 1999
Posts: 18,126
Likes: 174
From: WI
Drifting
Joined: Dec 2011
Posts: 1,743
Likes: 289
From: Chardon Ohio
Here's my info for reference: https://www.corvetteforum.com/forums...on-thread.html
I went with Super T10. Jim
I went with Super T10. Jim
Burning Brakes
Joined: Jan 2012
Posts: 943
Likes: 73
I have an 80 with the original T10 4 speed. If I had an automatic and was switching to a standard, I would be looking at an overdrive instead of the 4 speed.
Last edited by BlackC3vette; Mar 9, 2017 at 03:39 PM.
Melting Slicks
Joined: Dec 2009
Posts: 3,223
Likes: 652
From: Thunder Bay
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
Automatic cars have a removable trans cross member; manual cars have a welded-in cross member. Since your cross mount is ONLY for automatic cars, I'm not sure that any manual trans will "bolt right in".
The best advice would be from someone who has done this. But, going from auto to manual would be easier, since you have a removable cross mount to start with.
The best advice would be from someone who has done this. But, going from auto to manual would be easier, since you have a removable cross mount to start with.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
Melting Slicks
Joined: Jun 2011
Posts: 3,114
Likes: 597
My comparison was C3 vs C6 cars.
Then I tested cars with Tremec T56 6 speed transmissions (C6 corvettes)
Shifting up and down (2-3) (3-2) is a dream with the Tremec T56 Magnum.
My 78 feels like a C6 corvette shifter does.
After all the effort the T56 Magnum was well worth it.
Cost vs 4 speed is a different discussion. Wasn't cheap
Here is my conversion.
https://www.corvetteforum.com/forums...-corvette.html
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,062
From: altered state
St. Jude Donor '05
only had one muncie that shifted SO good it stuck out in my mind
The rest even with all the tricks, shifters etc were so so.
once you go to a modern trans esp with a nice shifter youll never look back they are amazing. Seems like way too much when youre buying but it is truly a mod you will forget about the $ the very first time you drive, totally changes the car in a good way and those long runs on the hwy are now realistic.
With most on the hwy going 65-75 makes sense youll enjoy the car a lot more and not be the slow poke watching the tach and temp gauge
Last edited by cv67; Mar 13, 2017 at 02:45 PM.
Burning Brakes
Joined: Jan 2010
Posts: 884
Likes: 84
From: New Boston, NH
Before I switched my 78 from auto to manual I test drove a few 4 speed cars. They shift like **** compared to modern cars.
That is the truth. I switched my 75 from Auto to a Super T10 and was very surprised at how bad the shifting was. Still, a lot more fun than the 3 speed auto.
That is the truth. I switched my 75 from Auto to a Super T10 and was very surprised at how bad the shifting was. Still, a lot more fun than the 3 speed auto.
Drifting
Joined: Dec 2011
Posts: 1,743
Likes: 289
From: Chardon Ohio
I will admit that the ST10 leaves a little to be desired. I went with it because it fit my skill level at the time and it has worked fine. But I would like to at some point replace it with a TKO600. Now that the pedals are there it wouldn't be too hard.
Jim
Jim
Racer
Joined: Sep 2015
Posts: 250
Likes: 29
I have a 1980 L48 with factory 4 speed (BW Super T-10). It has the removable crossmember as well. The original 2 bolt main is gone in favor of a 4 bolt main 383. While it was out, i had the 4 speed rebuilt with new clutch. In the future, i will definately go with a 5 or 6 speed, but for now with all the $ sunk into the motor, the rebuild of the 4 speed was the way to go for me.
Pro
Joined: Jan 2016
Posts: 502
Likes: 103
From: Reno Nevada
I am in the process of a auto to TKO600 5 speed conversion with SST's kit. I have not completed the install yet, but I will tell you their kit is VERY complete and appears very professional. Seems well worth the $$. In a year or so, I will know if the trans works as good as many have reported.
In fact, during the shipping process I had initially told them to include the wrong flywheel and AFTER it shipped, I called them in a panic to see if I could swap out the flywheel. They said no problem and without me asking, they called UPS had the package sent back to them and shipped me the correct flywheel all in the same time I would have had the original. I was astonished when the correct flywheel showed up. Highly recommended.
In fact, during the shipping process I had initially told them to include the wrong flywheel and AFTER it shipped, I called them in a panic to see if I could swap out the flywheel. They said no problem and without me asking, they called UPS had the package sent back to them and shipped me the correct flywheel all in the same time I would have had the original. I was astonished when the correct flywheel showed up. Highly recommended.
Instructor
Joined: Nov 2013
Posts: 220
Likes: 17
From: Pasadena MD
I am in the process of a auto to TKO600 5 speed conversion with SST's kit. I have not completed the install yet, but I will tell you their kit is VERY complete and appears very professional. Seems well worth the $$. In a year or so, I will know if the trans works as good as many have reported.
In fact, during the shipping process I had initially told them to include the wrong flywheel and AFTER it shipped, I called them in a panic to see if I could swap out the flywheel. They said no problem and without me asking, they called UPS had the package sent back to them and shipped me the correct flywheel all in the same time I would have had the original. I was astonished when the correct flywheel showed up. Highly recommended.
In fact, during the shipping process I had initially told them to include the wrong flywheel and AFTER it shipped, I called them in a panic to see if I could swap out the flywheel. They said no problem and without me asking, they called UPS had the package sent back to them and shipped me the correct flywheel all in the same time I would have had the original. I was astonished when the correct flywheel showed up. Highly recommended.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
I was going to suggest that you consider installing an overdrive [manual] transmission. But, the 1980 C3 came with a 3:08 rear axle and at 70mph, your engine will only be turning about 2500rpm. An O/D tranny is unnecessary for that; in fact, the car would be 'lugging' at lower speeds unless you keep the trans out of high range.
A standard 4-speed box will be fine for you.
P.S. Shift quality is mostly a function of the shifter, links and bushings. Certainly, the gearbox has its shifting nuances, too; but in my experience, installing a good quality shifter with snug links and bushings will make most manual trannies shift quite well.
A standard 4-speed box will be fine for you.
P.S. Shift quality is mostly a function of the shifter, links and bushings. Certainly, the gearbox has its shifting nuances, too; but in my experience, installing a good quality shifter with snug links and bushings will make most manual trannies shift quite well.
Melting Slicks
Joined: Jun 2011
Posts: 3,114
Likes: 597
And that is the problem by design. The T56 magnum shift quality vs any of the original 4-speed with any shifter installed is like night and day. Once you go forward you won't go back.
Last edited by cagotzmann; Mar 18, 2017 at 03:40 PM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
Actually, 2400-2500 rpm at 70 mph with stock diameter wheels. I have another car with 3.08 rear gear and it is dead-on with speedometer at highway speeds. It turns 2450 rpm at 70mph. My 3.36 C3 ('71) turns 2870 at 70mph.
A 3.08 rear gear and a .65 ratio high range O/D trans will turn about 1700 rpm at 70mph; and it will be lugging in high range at 40mph.
Finally, buy a better quality shifter to go with that 4-speed.
A 3.08 rear gear and a .65 ratio high range O/D trans will turn about 1700 rpm at 70mph; and it will be lugging in high range at 40mph.
Finally, buy a better quality shifter to go with that 4-speed.
Melting Slicks
Joined: Jun 2011
Posts: 3,114
Likes: 597
??? math doesn't work out. what do you call stock dia wheel ?
stock wheels ~ 27" rear 3.08 4th 1:1 ratio.
Try these
http://www.tremec.com/calculadora.php
http://americanpowertrain.com/p-7584...-analyzer.html
stock wheels ~ 27" rear 3.08 4th 1:1 ratio.
Try these
http://www.tremec.com/calculadora.php
http://americanpowertrain.com/p-7584...-analyzer.html