Corvette 4 speed questions
Thread Starter
Instructor
Joined: Jan 2005
Posts: 146
Likes: 1
From: Roanoke Rapids NC
Corvette 4 speed questions
Hey gang,
Well I'm one of the many that want to do an auto to manual swap... I have a 1974 L48/TH400 and hoping to put a T10 or M20 in it, don't really care which but it looks like T10s are cheaper and more plentiful in NC.
I've seen a few T10's in local listings but none advertise specifically as out of a Corvette and I'd like to know if there are any details I need to look for when hunting for a tranny. I heard I could reuse my TH400 driveshaft and slip yoke so that means it needs to have 32 spline output shaft right? What about input? # of grooves in input? Any other Corvette specific requirements?
Thanks in advance!
Brad
Well I'm one of the many that want to do an auto to manual swap... I have a 1974 L48/TH400 and hoping to put a T10 or M20 in it, don't really care which but it looks like T10s are cheaper and more plentiful in NC.
I've seen a few T10's in local listings but none advertise specifically as out of a Corvette and I'd like to know if there are any details I need to look for when hunting for a tranny. I heard I could reuse my TH400 driveshaft and slip yoke so that means it needs to have 32 spline output shaft right? What about input? # of grooves in input? Any other Corvette specific requirements?
Thanks in advance!
Brad
Melting Slicks
Joined: Feb 2006
Posts: 3,428
Likes: 5
From: Japan
This probably isn't much help but I had to get a smaller slip yoke to do my swap (M20). I bought the trans from eBay and put a rebuild kit and a new 1-2 slider in it...about $800 for the completed trans. I can send you a complete parts list and a job narrative if you think it will help...PM me with your email if you're interested...
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
The 74 Vette and all Vettes after 1970 had a 26 spline input shaft and any late mode T-10 with a 32 spline output shaft should have a 26 spline input shaft. Just be forewarned there were many useages of the T-10 in the late 70's and there are some out there with really wide spread ratios most fall into the normal range and you can decode the ratio of the transmission by the number of notches on the input shaft, be wary of ones with 4/5 notches, some of these were used in 305 Monzas and low powered cars and you could end up with a 3.26 first gear with gigantic ratio spreads between gears.
Drifting
Joined: Jul 2002
Posts: 1,944
Likes: 20
From: The only Corvettes in Highett Victoria
Why not 5 speed?
Stingraydriver,
I also have a 1974 L48 coupe, and I bought it from Solid LT1 just above. My car has a four speed, but depending on the diff ratio, you might find it revving a bit too fast at highway speeds, as I do. Obviously, the TH400 and any factory 4 speed still has a 1.00:1 top gear ratio, so ask yourself if you would still like a 1.00:1 top gear ratio.
If not, then you might as well fit a 5 speed with an overdrive top gear. This will bring the revs down to the 2,000-2,500 at 60 mph instead of 3,000-3,5000 rpm that you now have.
You will be doing a lot of hard work fitting either manual transmission, so you might as well fit the trans that will give you greater driving pleasure.
Seek advice from here and other places if you wish, but please consider a 5 speed before you commit yourself.
Regards from Down Under.
aussiejohn
I also have a 1974 L48 coupe, and I bought it from Solid LT1 just above. My car has a four speed, but depending on the diff ratio, you might find it revving a bit too fast at highway speeds, as I do. Obviously, the TH400 and any factory 4 speed still has a 1.00:1 top gear ratio, so ask yourself if you would still like a 1.00:1 top gear ratio.
If not, then you might as well fit a 5 speed with an overdrive top gear. This will bring the revs down to the 2,000-2,500 at 60 mph instead of 3,000-3,5000 rpm that you now have.
You will be doing a lot of hard work fitting either manual transmission, so you might as well fit the trans that will give you greater driving pleasure.
Seek advice from here and other places if you wish, but please consider a 5 speed before you commit yourself.
Regards from Down Under.
aussiejohn
Drifting
Joined: Feb 2008
Posts: 1,560
Likes: 4
From: Arlington texas
So many have done the swap from 4 to 5 speeds that you should be able to get you a 4sp from a member at a good price and you know it is the right one. I'm giving mine away but it is already spoken for.
Melting Slicks
Joined: Apr 2000
Posts: 3,341
Likes: 6
"M20" is an ordering code that basically means "wide ratio 4 speed". There are M20's that are Muncies and M20's that are Super T10's.
There are M21's (close ratio 4 speeds) of both flavors, too.
There was only one M22 (heavy duty, close ratio) and it was a Muncie.
There are M21's (close ratio 4 speeds) of both flavors, too.
There was only one M22 (heavy duty, close ratio) and it was a Muncie.
Drifting
Joined: Mar 2011
Posts: 1,347
Likes: 121
From: Kernersville NC
I have a 4spd that is coming out in a few weeks. Don't know your time line but this is a good transmission and I want to sell it. Drive shaft can go with it if you can use it. PM me if you are interested.
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Melting Slicks
Joined: Aug 2008
Posts: 2,200
Likes: 3
From: Lehigh county Pennsylvania
Anyway, stingraydriver74 is looking for the least expensive trans swap. 5 and 6 speed trans/shifter are far from cheap.
Racer
Joined: Nov 2004
Posts: 485
Likes: 1
From: Oakville ON
I agree with John. If you are going to do it, a 5 or 6 speed is much better pleasure to drive than a 4 speed. Now if $ is really tight and you don't do much highway driving then 4 speed is okay. If you do a lot of highway driving, gas savings will offset the cost of an OD tranny eventually. my 2c.
Drifting
Joined: Aug 2005
Posts: 1,443
Likes: 65
From: Wauconda IL
If you have a rear gear that is 3.55 or numerically larger and do ANY sort of highway driving, the 3 grand or higher revs at 60 MPH and above will quickly make up your mind whether you ever want to drive the car on the highway again.
I have a 3.70 gear and trying to stay up with the flow of traffic at 75 MPH for hours on end is just stupid.
Yes, the OD will GREATLY improve 'driving pleasure' in these situations.
Elm
Le Mans Master
Joined: Dec 2003
Posts: 5,381
Likes: 416
From: N J
1000 RPM is a bit more than a few hundred in my book-
If you have a rear gear that is 3.55 or numerically larger and do ANY sort of highway driving, the 3 grand or higher revs at 60 MPH and above will quickly make up your mind whether you ever want to drive the car on the highway again.
I have a 3.70 gear and trying to stay up with the flow of traffic at 75 MPH for hours on end is just stupid.
Yes, the OD will GREATLY improve 'driving pleasure' in these situations.
Elm
If you have a rear gear that is 3.55 or numerically larger and do ANY sort of highway driving, the 3 grand or higher revs at 60 MPH and above will quickly make up your mind whether you ever want to drive the car on the highway again.
I have a 3.70 gear and trying to stay up with the flow of traffic at 75 MPH for hours on end is just stupid.
Yes, the OD will GREATLY improve 'driving pleasure' in these situations.
Elm
3:70 here also, put in a 5 speed....WHAT A JOY.
Brad as long as you are going to be in there anyway, a few simple mods will fit a nice World Class T5 up there for not a lot of $$$$ and it will work just fine.
Drifting
Joined: Mar 2011
Posts: 1,347
Likes: 121
From: Kernersville NC
1000 RPM is a bit more than a few hundred in my book-
If you have a rear gear that is 3.55 or numerically larger and do ANY sort of highway driving, the 3 grand or higher revs at 60 MPH and above will quickly make up your mind whether you ever want to drive the car on the highway again.
I have a 3.70 gear and trying to stay up with the flow of traffic at 75 MPH for hours on end is just stupid.
Yes, the OD will GREATLY improve 'driving pleasure' in these situations.
Elm
If you have a rear gear that is 3.55 or numerically larger and do ANY sort of highway driving, the 3 grand or higher revs at 60 MPH and above will quickly make up your mind whether you ever want to drive the car on the highway again.
I have a 3.70 gear and trying to stay up with the flow of traffic at 75 MPH for hours on end is just stupid.
Yes, the OD will GREATLY improve 'driving pleasure' in these situations.
Elm
Thread Starter
Instructor
Joined: Jan 2005
Posts: 146
Likes: 1
From: Roanoke Rapids NC
Guys thank y'all very much for the input, I know the trans swap thread is a horse that's been beat to death twice and I've spent hours reading through posts, articles, etc.
I think the 5sp would be great but the way I priced everything I could do a 4sp AND an engine replacement for the same price. I'm neither looking for a super efficient cruiser nor a driveshaft snapping monster, just a really fun old car to drive which I think the 4sp can deliver. I only have 3.08 in the back so 1:1 final isn't outrageous.
A few tech questions for those who have done the swap if I may:
1. What type/where can I find the mount I need that would sit atop the bolt in crossmember for a 4 speed?
2. If I get the Hurst Comp+ shifter and installation kit for my year Corvette, will the shifter come up in the stock location of the console?
Thanks again!
Brad
I think the 5sp would be great but the way I priced everything I could do a 4sp AND an engine replacement for the same price. I'm neither looking for a super efficient cruiser nor a driveshaft snapping monster, just a really fun old car to drive which I think the 4sp can deliver. I only have 3.08 in the back so 1:1 final isn't outrageous.
A few tech questions for those who have done the swap if I may:
1. What type/where can I find the mount I need that would sit atop the bolt in crossmember for a 4 speed?
2. If I get the Hurst Comp+ shifter and installation kit for my year Corvette, will the shifter come up in the stock location of the console?
Thanks again!
Brad
Melting Slicks
Joined: Dec 2000
Posts: 3,363
Likes: 303
From: Lansdale 19446 PA
2024 C3 of the Year Finalist- Unmodified
St. Jude Donor '10-'11, '15, '19
1. What type/where can I find the mount I need that would sit atop the bolt in crossmember for a 4 speed?
2. If I get the Hurst Comp+ shifter and installation kit for my year Corvette, will the shifter come up in the stock location of the console?
Thanks again!
Brad
I converted my 78 to a 4 speed and installed the Hurst because I installed a Hurst on my 76 and loved it! No comparison to the stock shifter.
Good luck with your conversion, Brad
John
Le Mans Master
Joined: Jun 2007
Posts: 7,666
Likes: 1
From: Where it's always hot as Hell-South Louisiana.
St. Jude Donor '07-'08-'09-'10-'11-'12-'13
Guys thank y'all very much for the input, I know the trans swap thread is a horse that's been beat to death twice and I've spent hours reading through posts, articles, etc.
A few tech questions for those who have done the swap if I may:
1. What type/where can I find the mount I need that would sit atop the bolt in crossmember for a 4 speed?
2. If I get the Hurst Comp+ shifter and installation kit for my year Corvette, will the shifter come up in the stock location of the console?
Thanks again!
Brad
A few tech questions for those who have done the swap if I may:
1. What type/where can I find the mount I need that would sit atop the bolt in crossmember for a 4 speed?
2. If I get the Hurst Comp+ shifter and installation kit for my year Corvette, will the shifter come up in the stock location of the console?
Thanks again!
Brad
Do you have the factory original shifter and plan to use it ?
Thread Starter
Instructor
Joined: Jan 2005
Posts: 146
Likes: 1
From: Roanoke Rapids NC
Mikejpss: I don't have any shifter pieces yet and it looks like I'd pay as much for a stock setup as I would for the Hurst and I've been told the Hurst will feel better and mount just as easy/easier so I think I'll go with that, thanks for the suggestions.
I'm still unsure about how to put a 4 speed tranny mount on the auto crossmember.
Thanks everyone,
Brad
I'm still unsure about how to put a 4 speed tranny mount on the auto crossmember.
Thanks everyone,
Brad
Le Mans Master
Joined: Jun 2007
Posts: 7,666
Likes: 1
From: Where it's always hot as Hell-South Louisiana.
St. Jude Donor '07-'08-'09-'10-'11-'12-'13
Mikejpss: I don't have any shifter pieces yet and it looks like I'd pay as much for a stock setup as I would for the Hurst and I've been told the Hurst will feel better and mount just as easy/easier so I think I'll go with that, thanks for the suggestions.
I'm still unsure about how to put a 4 speed tranny mount on the auto crossmember.
Thanks everyone,
Brad
I'm still unsure about how to put a 4 speed tranny mount on the auto crossmember.
Thanks everyone,
Brad
Good to know about the Hurst shifter , and that it will mount in the existing hole, and function the same way as the original .
Be sure to check your trans tail shaft section to insure the Hurst shifter mounting holes / threads are in good shape.
It appears that a Hurst setup is a bit more $$, but am sure it is well worth the price. I have 2 sets of original shifters and both are kind of sloppy.
Thread Starter
Instructor
Joined: Jan 2005
Posts: 146
Likes: 1
From: Roanoke Rapids NC
I am told the 4 speed trans will mount to the auto X member using the same rubber mount. Give me a few weeks and I will report back, looks like I will be doing my 4 speed swap around the week of March 12th.
Good to know about the Hurst shifter , and that it will mount in the existing hole, and function the same way as the original .
Be sure to check your trans tail shaft section to insure the Hurst shifter mounting holes / threads are in good shape.
It appears that a Hurst setup is a bit more $$, but am sure it is well worth the price. I have 2 sets of original shifters and both are kind of sloppy.
Good to know about the Hurst shifter , and that it will mount in the existing hole, and function the same way as the original .
Be sure to check your trans tail shaft section to insure the Hurst shifter mounting holes / threads are in good shape.
It appears that a Hurst setup is a bit more $$, but am sure it is well worth the price. I have 2 sets of original shifters and both are kind of sloppy.
You're right on the shifters, a brand new hurst setup will run $350 and some used options cheaper on ebay but the hursts should be much tighter and solid mounting.
Keep us updated on your progress! I'll do the same.
Brad