Manual transmission swap - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Michael A. K. G · 08-19-2002, 11:24 AM

I have a '72 C-10 with a 250 inline six, three-on-the-tree, and I think 3.73 gears in back. It revs HIGH on the highway, but behaves nicely on city streets (I know it's a truck, and it was meant to do that).

I also kinda like the column shift. Was there ever a four or five speed column shift? If so, what years and models were they produced for?

I'd rather avoid the floor shift conversion because of the low hump, and I like the cab room the column shift frees up.

I'm aware that I may also need to reduce the gear ratio in back if the extra gear is a granny gear.

TIA.

JimKshortstep4x4 · 08-20-2002, 10:09 AM

I have never seen anything but (3) speeds on the column, but you could go with an overdrive and this would give you (6) speeds.

Jim

Michael A. K. G · 08-20-2002, 10:40 AM

Overdrive?

Every overdrive I've ever dealt with has been an integral part of the transmission. Please elaborate. Where do I find an overdrive that isn't? How is it controlled?

This sounds quite interesting.

JimKshortstep4x4 · 08-20-2002, 10:48 AM

The overdrive that I think would be great is fairly expensive. They bolt up to your transmission as a replacement tailshaft. I don't have their website available, but I can get it tonight.

Jim

Longhorn Man · 08-20-2002, 04:33 PM

Here you go, it is an overdrive/underdrive...indestructable, and in reality, probably less than a good 5 speed or 700 R4 conversion.
http://www.gearvendors.com/commercial.html

**Palf70Step** · 08-20-2002, 10:17 PM

This is odd topic a bit, but when I was in Japan, many of the trucks had 4 & 5 speeds on the tree. It freaked me out when I went to find reverse and got first instead.

Unfortunately, like anything with long shift rods and linkages, if you don't keep up with them they tended to get sloppy too.

By the way, if your like me, that fifth gear on the tree took out many kneecaps.

Michael A. K. G · 08-20-2002, 10:56 PM

Quote:

Originally posted by longhornmail
Here you go, it is an overdrive/underdrive...indestructable, and in reality, probably less than a good 5 speed or 700 R4 conversion.
http://www.gearvendors.com/commercial.html

I do appreciate that, but $2500 is not less than a good 5 speed conversion. I do most of the work myself (including a rebuild if needed) -- never done a GM, but it CAN'T be harder than impossible Ford bearings.

That's a bit out of my price range, though I do think it sounds very interesting. BTW, they seem to have applications only for 4 speeds, not 3 speeds.

I was hoping there was a relatively easy junkyard swap-in, with little more than driveshaft worries, and maybe a hole to cut in the floor.

Thanks anyway.

The Japanese 5speed is interesting, but I'm not terribly likely to find that in a junkyard.

Longhorn Man · 08-20-2002, 11:06 PM

ouch...my fault, been quite a while since I looked at them.
They are cheaper than a 700R4 profesionally built to handle high horse power, and they are nearly indestructable.
I have seen one on a 3 speed before. (the site did say more aplications available)
Sorry bout the mislead on the price.

primerib · 08-21-2002, 02:24 AM

I also have a 72 with a 250 and the column shift, and plan to keep it that way. I can't afford the gear-vendor overdrive, and I don't want to fool around with a T5 from an S-10. I did find some information on a Borg-Warner overdrive produced in the 60's that was fitted in the tailshaft of the Saginaw 3 speed as an option in some passenger cars.

I managed to track one down, with the transmission, and I bought it from a guy up north. The dimensions of the Saginaw with the Borg-Warner are *supposedly* the same as the straight Saginaw. I can't vouch for that. Yet. Unfortunately, it is still in the crate in my garage. I need to get it looked at and flushed, and get started on installing it. My truck is a daily driver, and I'm very short on time, money and mechanical experience.

If you are interested in the info I've found (links, etc.), I'll be happy to send you what I have.

Good luck with your quest!

Michael A. K. G · 08-21-2002, 10:30 AM

Quote:

Originally posted by primerib

If you are interested in the info I've found (links, etc.), I'll be happy to send you what I have.

Good luck with your quest!

Indeed, I'll take you up on that.

That sounds like a truly fantastic solution, that doesn't even require driveshaft work.

C10 - C90 Bill · 08-21-2002, 10:57 PM

Has anyone ever tried a 3-Speed Aux. trans from a 2 Ton or 3 Ton truck. (SM4??) Have heard of it one time on a pick-up thru another person that saw it, but never got the details on it.

primerib · 08-23-2002, 01:36 PM

Michael,

Sent you an e-mail. Let me know if you didn't get it.

Blazer1970 · 08-23-2002, 02:14 PM

Pretty sure that the O/D set-up that primerib speaks of was an option on trucks also. There are people on this board who have them. Post a new topic with Saginaw w/ O/D in the subject line, and you should raise some activity.

primerib · 08-23-2002, 10:03 PM

I believe you are correct, Blazer. I have heard of the O/D being offered on pick-ups up to '68 (?), but I'm no historian. The overdrive seems to be more common in cars, though. Anyone know the stock location of the overdrive T-handle on pick-ups?

Michael A. K. G · 08-23-2002, 10:12 PM

Thanks; this is quite cool.

I'll have to make a junkyard run and go looking for things like that. The docs primerib sent have enough pictures in them that I can recognize this thing.

Yeah, I know it's a longshot. But it does appear this was used in quite a lot of models, which helps.

1967LWBstepside · 08-23-2002, 11:29 PM

Quote:

Originally posted by Michael A. K. G
The docs primerib sent have enough pictures in them that I can recognize this thing.

Could you either post those docs or e-mail them to me? Thanks.

Mike

mikep · 08-24-2002, 01:15 AM

$2500 buys a hell of a lot of gas ! How about someone who didnt just suck down a six pack tell me how long it would take to start recouping my investment given that I currently get about 13 mpg in the city and would possibly get 18 if I had an overdrive unit. I drive 1000 miles a month or so and the yearly averaged cost of a gallon of 89 octane where I live is $1.24.

Michael A. K. G · 08-24-2002, 09:38 PM

Saving gas isn't the motivation. Very few economy mods are worth it, especially for an old truck.

The motivation is that this little 250 inline 6 is LOUD at 70 MPH, and it doesn't sound very happy.

$2500 is still out of my price range. $75 or $100 for a pull-yer-own junkyard overdrive is more like it.

C10 - C90 Bill · 08-25-2002, 12:36 AM

I have a '72 307 3-Speed with 373 gears and I can only go no more than 60 MPH without it seeming like it's reving too much. Maybe I'm a little conserative, but that's where I draw the line at. I sure would like to find an inexpensive way too, to get some kind of overdrive. What I'm going to try when I wear out this set is to go to taller tires. Love to find a good used original OD set up tho.

Michael A. K. G · 08-25-2002, 05:20 PM

Lower (numerically) differential gears would have the same effect as taller tires, without the steering and handling ramifications. If you want to raise the vehicle for clearance, tires are the easiest way to do it. But the tradeoffs are significant, especially if you have manual steering. Raising the center of gravity can destabilize the truck in turns, and it can be a real muscle builder to turn big tires, especially at low speeds or on sharp curves.

Can you tell I live in the mountains?

But I won't go either route because it will also raise 1st gear. I like 1st gear where it is.

08-19-2002, 11:24 AM	#1
Michael A. K. G Registered User Join Date: Jul 2002 Location: California central coast Posts: 126	Manual transmission swap I have a '72 C-10 with a 250 inline six, three-on-the-tree, and I think 3.73 gears in back. It revs HIGH on the highway, but behaves nicely on city streets (I know it's a truck, and it was meant to do that). I also kinda like the column shift. Was there ever a four or five speed column shift? If so, what years and models were they produced for? I'd rather avoid the floor shift conversion because of the low hump, and I like the cab room the column shift frees up. I'm aware that I may also need to reduce the gear ratio in back if the extra gear is a granny gear. TIA.

08-20-2002, 10:17 PM	#6
Palf70Step State of Confusion! Join Date: Jul 2002 Location: Gulfport, MS USA Posts: 46,761	This is odd topic a bit, but when I was in Japan, many of the trucks had 4 & 5 speeds on the tree. It freaked me out when I went to find reverse and got first instead. Unfortunately, like anything with long shift rods and linkages, if you don't keep up with them they tended to get sloppy too. By the way, if your like me, that fifth gear on the tree took out many kneecaps. __________________ Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God!

08-23-2002, 02:14 PM	#13
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,510	Pretty sure that the O/D set-up that primerib speaks of was an option on trucks also. There are people on this board who have them. Post a new topic with Saginaw w/ O/D in the subject line, and you should raise some activity. __________________ Tim

08-24-2002, 01:15 AM	#17
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	$2500 buys a hell of a lot of gas ! How about someone who didnt just suck down a six pack tell me how long it would take to start recouping my investment given that I currently get about 13 mpg in the city and would possibly get 18 if I had an overdrive unit. I drive 1000 miles a month or so and the yearly averaged cost of a gallon of 89 octane where I live is $1.24. __________________ No truck :-( Last edited by mikep; 08-24-2002 at 01:22 AM.

08-25-2002, 05:20 PM	#20
Michael A. K. G Registered User Join Date: Jul 2002 Location: California central coast Posts: 126	Lower (numerically) differential gears would have the same effect as taller tires, without the steering and handling ramifications. If you want to raise the vehicle for clearance, tires are the easiest way to do it. But the tradeoffs are significant, especially if you have manual steering. Raising the center of gravity can destabilize the truck in turns, and it can be a real muscle builder to turn big tires, especially at low speeds or on sharp curves. Can you tell I live in the mountains? But I won't go either route because it will also raise 1st gear. I like 1st gear where it is. Last edited by Michael A. K. G; 08-26-2002 at 11:02 AM.

08-20-2002, 10:09 AM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	I have never seen anything but (3) speeds on the column, but you could go with an overdrive and this would give you (6) speeds. Jim

08-20-2002, 10:40 AM	#3
Michael A. K. G Registered User Join Date: Jul 2002 Location: California central coast Posts: 126	Overdrive? Every overdrive I've ever dealt with has been an integral part of the transmission. Please elaborate. Where do I find an overdrive that isn't? How is it controlled? This sounds quite interesting.

08-20-2002, 10:48 AM	#4
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	The overdrive that I think would be great is fairly expensive. They bolt up to your transmission as a replacement tailshaft. I don't have their website available, but I can get it tonight. Jim

08-20-2002, 04:33 PM	#5
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Here you go, it is an overdrive/underdrive...indestructable, and in reality, probably less than a good 5 speed or 700 R4 conversion. http://www.gearvendors.com/commercial.html

08-20-2002, 11:06 PM	#8
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	ouch...my fault, been quite a while since I looked at them. They are cheaper than a 700R4 profesionally built to handle high horse power, and they are nearly indestructable. I have seen one on a 3 speed before. (the site did say more aplications available) Sorry bout the mislead on the price.

08-21-2002, 02:24 AM	#9
primerib Registered User Join Date: Nov 2001 Location: Ft.Worth, TX Posts: 35	I also have a 72 with a 250 and the column shift, and plan to keep it that way. I can't afford the gear-vendor overdrive, and I don't want to fool around with a T5 from an S-10. I did find some information on a Borg-Warner overdrive produced in the 60's that was fitted in the tailshaft of the Saginaw 3 speed as an option in some passenger cars. I managed to track one down, with the transmission, and I bought it from a guy up north. The dimensions of the Saginaw with the Borg-Warner are supposedly the same as the straight Saginaw. I can't vouch for that. Yet. Unfortunately, it is still in the crate in my garage. I need to get it looked at and flushed, and get started on installing it. My truck is a daily driver, and I'm very short on time, money and mechanical experience. If you are interested in the info I've found (links, etc.), I'll be happy to send you what I have. Good luck with your quest!

08-21-2002, 10:57 PM	#11
C10 - C90 Bill Registered User Join Date: Nov 2001 Location: Moneta, VA USA Posts: 3,071	Has anyone ever tried a 3-Speed Aux. trans from a 2 Ton or 3 Ton truck. (SM4??) Have heard of it one time on a pick-up thru another person that saw it, but never got the details on it.

08-23-2002, 01:36 PM	#12
primerib Registered User Join Date: Nov 2001 Location: Ft.Worth, TX Posts: 35	Michael, Sent you an e-mail. Let me know if you didn't get it.

08-23-2002, 10:03 PM	#14
primerib Registered User Join Date: Nov 2001 Location: Ft.Worth, TX Posts: 35	I believe you are correct, Blazer. I have heard of the O/D being offered on pick-ups up to '68 (?), but I'm no historian. The overdrive seems to be more common in cars, though. Anyone know the stock location of the overdrive T-handle on pick-ups?

08-23-2002, 10:12 PM	#15
Michael A. K. G Registered User Join Date: Jul 2002 Location: California central coast Posts: 126	Thanks; this is quite cool. I'll have to make a junkyard run and go looking for things like that. The docs primerib sent have enough pictures in them that I can recognize this thing. Yeah, I know it's a longshot. But it does appear this was used in quite a lot of models, which helps.



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08-24-2002, 09:38 PM	#18
Michael A. K. G Registered User Join Date: Jul 2002 Location: California central coast Posts: 126	Saving gas isn't the motivation. Very few economy mods are worth it, especially for an old truck. The motivation is that this little 250 inline 6 is LOUD at 70 MPH, and it doesn't sound very happy. $2500 is still out of my price range. $75 or $100 for a pull-yer-own junkyard overdrive is more like it.

08-25-2002, 12:36 AM	#19
C10 - C90 Bill Registered User Join Date: Nov 2001 Location: Moneta, VA USA Posts: 3,071	I have a '72 307 3-Speed with 373 gears and I can only go no more than 60 MPH without it seeming like it's reving too much. Maybe I'm a little conserative, but that's where I draw the line at. I sure would like to find an inexpensive way too, to get some kind of overdrive. What I'm going to try when I wear out this set is to go to taller tires. Love to find a good used original OD set up tho.

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