Anyone done a 6 Speed Conversion? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

uk72step · 12-14-2005, 10:59 AM

Hi,
Has anyone here done a 6 Speed Manual conversion in their truck?
I have a 72 short step (work in progress) and was toying with the idea. Is this a practical project? What's involved and is it worth it?

Running a 350 SBC with a TH400 at present. Looks like the ration in the 6sp would give a nice balance on accelaration when wanted but also allow the RPM to cut down on cruising...

Cheers
Lee

shifty · 12-14-2005, 11:11 AM

I am dropping 6spd in mine but with an LS1. A Thread with more info and a picture gallery of my truck and the swap is in my signature.

GRAYGHOST · 12-15-2005, 09:32 AM

I put a 6spd in my 70 swb. I love it. The one I used is from 93-97 camero. For the hydralic clutch I used a master cylinder from a 94 s10 truck, made my own rod. The slave cylinder is from 93-97 camero. For the hydralic line, I got it from classic tube (custom length 42").To connect the line to the cylinders, you have to buy an adapter, because the orignal line pushes in and is held in with a roll pin. There is a company that makes the adapter, McLeod Industries, the part #139026. They do have web site, mcloedind.com. The adaprters are kind of expincive 35.00 each, you need two. The flyweel will depend on what year your motor is, if you have a one or two piece rear seal. The clutch kit I used was for a 94 camero. The yoke for a 350 trans will work on the 6spd. The shifter will be about 3" in front of the bench seat, I made a custom shifter. When you put the trans in, you will have to cut out most of the hump, unless your truck has the 4" hump. The swap is not hard, just rounding up all the parts. Let me know if you have any questions, I'll be glad to help. I'll try to take some pictures and post them.

Huck · 12-15-2005, 10:00 AM

If 5th and 6th are both overdrives--I would think 6th would be a stretch given the wind resistance of our trucks.
How did you handle the mechanical speedometer issue as the newer 5-6 speeds are electronic sensed?

crazy longhorn · 12-15-2005, 05:02 PM

I agree with Huck on the double overdrive, I think it would be hard to really use it on a "brick". I did run a Richmond 6 in my longhorn, lots of fun, but for the cost you might look at the Tremec TKO 5 spd

L

KCW · 12-15-2005, 06:32 PM

I put a Richmond 6 speed in mine. Still a work in progress but the tranny fits the stock mount real nice.

crazy longhorn · 12-15-2005, 06:45 PM

Quote:

Originally Posted by KCW

I put a Richmond 6 speed in mine. Still a work in progress but the tranny fits the stock mount real nice.

Give up the specs on your combo! Also what ratios did you get in the trans? I am sure you will like the Richmond

L

GRAYGHOST · 12-15-2005, 09:06 PM

The advantage of having a 6spd is you can run 4:10 gears and only 1800 rpm at 75 mph. When I had a 350 trans with 3:08 gears, I would tach 3000 rpm at 70 mph. Also the truck would pull hard at the top of first gear and the bottom of second gear, it felt a little slugish everywhere else. With 6spd, the truck pulls much harder in all the gears, no dead spots. Sixth gear is used when you are cruzing on the freeway. I used a Autometer electronic speedometer.

FirstGen · 12-15-2005, 11:34 PM

double overdrive is the only way my 500 hp small block gets 19.6MPG on the highway...

Willy Prost · 12-16-2005, 09:43 AM

I have a .68 OD on my tremec TKO 5 speed. The OD is useful when maintaining 40mph or more on a level surface. I kinda wish I had a choice of an extra gear between the .68 OD and 1:1 though.

KCW · 12-16-2005, 10:42 AM

I have a 72 GMC SWB that I built a 454 for road trips.....its 9:1 compression aluminum headed (ported, polished, matched, trick grind) choppy cam. I put a Richmond ROD tranny behind it. They have different ratios depending on your application and Rear Gears I called the tech support to get the best set. I have a ford 9" and art morrison rear suspension with 3:7 ratio so I went with the .68 final (6th gear). I put a center force clutch with Tilton clutch hydraulics to work it. Used a 11 inch bell housing off of a 63 Vette. Hope this helps.....if you need any other info let me know. I still havnt driven it yet.....the body is in the body shop getting ready for paint.

12-14-2005, 11:11 AM	#2
shifty Questionable Join Date: Mar 2005 Location: Atlanta Posts: 13,376	Re: Anyone done a 6 Speed Conversion? I am dropping 6spd in mine but with an LS1. A Thread with more info and a picture gallery of my truck and the swap is in my signature. __________________ If I've got anything up for grabs, it'll be here: 7-hole gauge cluster for a 67-72 p/u FREE (link) I can't check the forum daily. If I don't reply to you within 24 hours, drop me a PM! I'm (hopefully) still alive and will reply faster to a PM.

12-15-2005, 09:32 AM	#3
GRAYGHOST Registered User Join Date: Aug 2005 Location: Spring, Tx. Posts: 31	Re: Anyone done a 6 Speed Conversion? I put a 6spd in my 70 swb. I love it. The one I used is from 93-97 camero. For the hydralic clutch I used a master cylinder from a 94 s10 truck, made my own rod. The slave cylinder is from 93-97 camero. For the hydralic line, I got it from classic tube (custom length 42").To connect the line to the cylinders, you have to buy an adapter, because the orignal line pushes in and is held in with a roll pin. There is a company that makes the adapter, McLeod Industries, the part #139026. They do have web site, mcloedind.com. The adaprters are kind of expincive 35.00 each, you need two. The flyweel will depend on what year your motor is, if you have a one or two piece rear seal. The clutch kit I used was for a 94 camero. The yoke for a 350 trans will work on the 6spd. The shifter will be about 3" in front of the bench seat, I made a custom shifter. When you put the trans in, you will have to cut out most of the hump, unless your truck has the 4" hump. The swap is not hard, just rounding up all the parts. Let me know if you have any questions, I'll be glad to help. I'll try to take some pictures and post them.

12-15-2005, 10:00 AM	#4
Huck Senior Member Join Date: Jun 2001 Location: Shelbyville, KY Posts: 3,269	Re: Anyone done a 6 Speed Conversion? If 5th and 6th are both overdrives--I would think 6th would be a stretch given the wind resistance of our trucks. How did you handle the mechanical speedometer issue as the newer 5-6 speeds are electronic sensed?

12-15-2005, 05:02 PM	#5
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	Re: Anyone done a 6 Speed Conversion? I agree with Huck on the double overdrive, I think it would be hard to really use it on a "brick". I did run a Richmond 6 in my longhorn, lots of fun, but for the cost you might look at the Tremec TKO 5 spd L __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

12-15-2005, 06:32 PM	#6
KCW 1972 GMC 2006 GMC Join Date: Feb 2005 Location: Everett, WA Posts: 96	Re: Anyone done a 6 Speed Conversion? I put a Richmond 6 speed in mine. Still a work in progress but the tranny fits the stock mount real nice.

12-14-2005, 10:59 AM	#1
uk72step outta the car velocityboy Join Date: Nov 2004 Location: Scotland Posts: 112	Anyone done a 6 Speed Conversion? Hi, Has anyone here done a 6 Speed Manual conversion in their truck? I have a 72 short step (work in progress) and was toying with the idea. Is this a practical project? What's involved and is it worth it? Running a 350 SBC with a TH400 at present. Looks like the ration in the 6sp would give a nice balance on accelaration when wanted but also allow the RPM to cut down on cruising... Cheers Lee __________________ ..give it a turn here, take some wedge out there, we'll win some races...

12-15-2005, 09:06 PM	#8
GRAYGHOST Registered User Join Date: Aug 2005 Location: Spring, Tx. Posts: 31	Re: Anyone done a 6 Speed Conversion? The advantage of having a 6spd is you can run 4:10 gears and only 1800 rpm at 75 mph. When I had a 350 trans with 3:08 gears, I would tach 3000 rpm at 70 mph. Also the truck would pull hard at the top of first gear and the bottom of second gear, it felt a little slugish everywhere else. With 6spd, the truck pulls much harder in all the gears, no dead spots. Sixth gear is used when you are cruzing on the freeway. I used a Autometer electronic speedometer.

12-15-2005, 11:34 PM	#9
FirstGen Just Don't Stop! Join Date: Feb 2004 Location: Dallas Posts: 1,239	Re: Anyone done a 6 Speed Conversion? double overdrive is the only way my 500 hp small block gets 19.6MPG on the highway... __________________ 1968 C10 build in process TT LSA/6L90e/9"

12-16-2005, 09:43 AM	#10
Willy Prost Senior Member Join Date: Jan 2000 Location: Arlington, VA Posts: 398	Re: Anyone done a 6 Speed Conversion? I have a .68 OD on my tremec TKO 5 speed. The OD is useful when maintaining 40mph or more on a level surface. I kinda wish I had a choice of an extra gear between the .68 OD and 1:1 though.

12-16-2005, 10:42 AM	#11
KCW 1972 GMC 2006 GMC Join Date: Feb 2005 Location: Everett, WA Posts: 96	Re: Anyone done a 6 Speed Conversion? I have a 72 GMC SWB that I built a 454 for road trips.....its 9:1 compression aluminum headed (ported, polished, matched, trick grind) choppy cam. I put a Richmond ROD tranny behind it. They have different ratios depending on your application and Rear Gears I called the tech support to get the best set. I have a ford 9" and art morrison rear suspension with 3:7 ratio so I went with the .68 final (6th gear). I put a center force clutch with Tilton clutch hydraulics to work it. Used a 11 inch bell housing off of a 63 Vette. Hope this helps.....if you need any other info let me know. I still havnt driven it yet.....the body is in the body shop getting ready for paint.



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