To Convert Auto tranny to 5 speed or not to convert...that is the Question
#1
Instructor
Thread Starter
To Convert Auto tranny to 5 speed or not to convert...that is the Question
I've got a 74 automatic transmission (400) that will probably need to be rebuilt and/or serviced during my restoration which could raise the budget. I'm considering converting it to a 4 or 5 speed manual. What are some of your experiences... (good or bad)?
#2
Le Mans Master
IF you really want to swap, I'd go to a 5 speed/ Take advantage of the OD. I'd bet you'll spend more doing the conversion unless you already have a manual trans laying around. A TH400 is not all that tough to overhaul. You'll need a few "above" stock parts, but the basic overhaul kit can be had for $150 tops. There are a stack of tricks you can do, 4L80 clutches, HD sprag and forward drum, and a top shift kit. Another option would be to go with an automatic OD like a 200-4R. My $0.05
#3
Take a look at my adventure. Would I do it again 100% yes if money is not your concern.
https://www.corvetteforum.com/forums...-corvette.html
Last edited by cagotzmann; 05-18-2017 at 07:25 PM.
#4
Race Director
I have a very nicely restored set of pedals and clutch linkage available, if you or anyone else is interested send a PM
#5
Instructor
Thread Starter
I was in the same situation when my failing TH350 needed some work. So I went with a T56 Magnum 6-speed instead. Its a lot of work and $$$. But there are some more complete kits now available compared to when I did my conversion.
Take a look at my adventure. Would I do it again 100% yes if money is not your concern.
https://www.corvetteforum.com/forums...-corvette.html
Take a look at my adventure. Would I do it again 100% yes if money is not your concern.
https://www.corvetteforum.com/forums...-corvette.html
Last edited by dreno73; 05-18-2017 at 07:39 PM.
#6
Race Director
Member Since: Mar 2003
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Howard, you know at some point i will have money and score those sweet pedals off you....
For years i liked auto, never cared about hunting for gears,
Then as years pass and my tastes changed i find myself knowing i wont be content if i dont swap the auto in my 69 to 4 speed, its an old school custom racer theme build so a 4 speed is a must, likely a noisy rock crusher, it to me makes a vette a vette, like side pipes and a big block,
So i say to tina my wife will you mind shifting when you drive the vette, she says, dont all vettes have sticks?, their vettes.
Lol,
So im sold, but in the end you are asking about YOUR car, the only opinion that counts on your car is YOURS.
For years i liked auto, never cared about hunting for gears,
Then as years pass and my tastes changed i find myself knowing i wont be content if i dont swap the auto in my 69 to 4 speed, its an old school custom racer theme build so a 4 speed is a must, likely a noisy rock crusher, it to me makes a vette a vette, like side pipes and a big block,
So i say to tina my wife will you mind shifting when you drive the vette, she says, dont all vettes have sticks?, their vettes.
Lol,
So im sold, but in the end you are asking about YOUR car, the only opinion that counts on your car is YOURS.
#7
Team Owner
Autos are for women, girly men, and drag racing
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Metalhead140 (05-19-2017)
#8
Instructor
I converted from auto to manual with a Sliver Sport Transmission direct fit kit using the TKO500 transmission .
Absolutely the best mod i have done the Tremec transmission is a great transmission to use, the shifting is very precise and the 5th overdrive makes the Vette just a dream to drive on the highway
Absolutely the best mod i have done the Tremec transmission is a great transmission to use, the shifting is very precise and the 5th overdrive makes the Vette just a dream to drive on the highway
#9
Burning Brakes
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TheSkunkWorks (05-19-2017)
#11
Team Owner
Wouldn't it be simpler to swap to an overdrive automatic?
But, if you really prefer a manual box, go for it.
But, if you really prefer a manual box, go for it.
#12
Race Director
Member Since: Jan 2000
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2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
"Real" cars....especially Vette's have 3 pedals!!!
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Metalhead140 (05-19-2017)
#13
Le Mans Master
I seriously doubt that I would have hung onto my one-owner '78 SAE thru all of these years had I not converted it over to a stick ages ago. IMHO, The Single Best mod I ever made which did more to transform what was merely a sporty car into a sportscar than anything else. I've never even considered an auto in the other vettes I've owned since. Go for it!
#14
Race Director
I think I have done 8 or 9 of these by now. I have never had anyone say that it was the wrong thing to do or a waste of money. Everyone has said it totally transforms the car and makes driving it much nicer. I say do it. I have used SST a few times and just finished one a few weeks ago. They have good customer service and are very nice to deal with. You won't regret it.
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SSTGene (06-14-2017)
#15
If you are going to keep the engine near stock levels (and/or lighten the car substantially) and you are a sane, non-abusive driver then the least expensive approach is to roll your own installation with a F body WC T5. $400-500 for good used trans, $100 driveshaft shortened, 26 spline clutch disk, fabricate a shifter and some wedge/beveled washers with a modified lower bracket. That approach does require some minor fabrications skills/tools and another issue that it is getting harder to find a good used trans anymore. Since you have an auto there are other parts needed as well, as identified above.
If you will be adding power or you powershift at redline with every shift, then a more robust TKO is the better approach. The various kits available in the aftermarket offer all needed with little to no fabrication required.
If you will be adding power or you powershift at redline with every shift, then a more robust TKO is the better approach. The various kits available in the aftermarket offer all needed with little to no fabrication required.
Last edited by Dynra Rockets; 05-19-2017 at 08:37 AM.
#16
Melting Slicks
I finally did the swap to a TKO 600 a few years back and its the best thing I ever did to the car. I would highly recommend the swap, assuming you like driving a stick. (And I would suggest if you don't you probably shouldn't be driving a Corvette. )
As for the availability of good used transmissions the market is flooded with them. All those four speeds that are being replaced with five speeds are going somewhere. Check out eBay. Last itme I looked, there were pages of them. I think I have a couple kicking around as well. With that said, go with a five speed. The extra gear makes the car much more driveable.
As for the availability of good used transmissions the market is flooded with them. All those four speeds that are being replaced with five speeds are going somewhere. Check out eBay. Last itme I looked, there were pages of them. I think I have a couple kicking around as well. With that said, go with a five speed. The extra gear makes the car much more driveable.
#17
Pro
Another vote for Sliver Sport Transmission's TKO500. I was in the same situation with my Turbo400 and ended up using SST's kit. Their customer service is amazing and while I am not done installing it, the kit seems to include every nut, bolt and special doodad that you need to make it look like a OE install. Very nice. Everything from the driveline to the foot pedals is in the kit.
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SSTGene (06-14-2017)
#18
Le Mans Master
If you are going to keep the engine near stock levels (and/or lighten the car substantially) and you are a sane, non-abusive driver then the least expensive approach is to roll your own installation with a F body WC T5. $400-500 for good used trans, $100 driveshaft shortened, 26 spline clutch disk, fabricate a shifter and some wedge/beveled washers with a modified lower bracket. That approach does require some minor fabrications skills/tools and another issue that it is getting harder to find a good used trans anymore. Since you have an auto there are other parts needed as well, as identified above.
If you will be adding power or you powershift at redline with every shift, then a more robust TKO is the better approach. The various kits available in the aftermarket offer all needed with little to no fabrication required.
If you will be adding power or you powershift at redline with every shift, then a more robust TKO is the better approach. The various kits available in the aftermarket offer all needed with little to no fabrication required.
I know it's not the best OD trans out there, but so far so good.
I hope I didn't just jinx myself.
#19
Race Director
My 73, BB, TH-400, 3.36 may be going through this mod to. I just received two quotes from SST Transmissions. One is for their Auto O.D. $4,800.00 and the TKO-600, $5,300.00. Both kits include everything you need to swap to the O.D. auto or the 5 speed manual. Looking at the parts included, the kits use top grade hardware and components. The question is simply, what are you going to use the car for and what performance upgrades are you planning for the motor. The Final gearing for both transmissions are about equal and will only drop my highway cruising rpm from 3071 down to 2556 @ 70 mph unless I go to the .64 wide ratio tko-600 which will drop the rpm to about 2300 @ 70. Another option I've been looking at is keeping the TH-400 and going with a Gear Vendors over-under drive.
Last edited by OldCarBum; 05-19-2017 at 01:08 PM.