Register or Log In To remove these advertisements. |
|
|
|
Thread Tools | Display Modes |
06-29-2010, 10:28 PM | #1 |
Registered User
Join Date: May 2010
Location: ambler, pa
Posts: 325
|
3 speed to 4 speed swap
hi Guys
Interested in swapping my 68 GMC with a 292 from a 3 speed to a 4 speed. As far as the driveshaft goes is there any differences, or can I reuse what I have? Also want to know what 4 speed should I use and what years I might find them in. Is there an overdrive version? Thanks for the help
__________________
Just would like the snow to stop so I can actually work on my truck!!!!!!!!!!! |
06-29-2010, 10:52 PM | #2 |
Grandpa in the rustmobile...
Join Date: Nov 2008
Location: Spokane WA/Viola TN
Posts: 11,422
|
Re: 3 speed to 4 speed swap
4spd like that originally came in these trucks or a car 4 spd?
__________________
John Goose-1968 C10 355,9.32-1CR, Vortec Heads ,262 voodoo, 3.73:1 3OTT (HS ride/beater/farm truck) http://67-72chevytrucks.com/vboard/s...d.php?t=317684 Grams 53-1953 Chevrolet Belair http://67-72chevytrucks.com/vboard/s...=1#post4327784 1969 Chevy C10 Shortbed 4.5/6?" Frame off resto http://67-72chevytrucks.com/vboard/s...d.php?t=548136 1999 Toyota Tacoma 4x4 |
06-29-2010, 11:02 PM | #3 |
Senior Member
Join Date: Jun 2010
Location: Orlando, Florida
Posts: 2,510
|
Re: 3 speed to 4 speed swap
I asked a similar question a few weeks ago and got some excellent answers. Here's a link to the thread.
http://67-72chevytrucks.com/vboard/s...d.php?t=407083
__________________
71 Chevy C10 Shortbed Stepside. LT1 with 4l60E. Just got back from painter, in assembly now. |
06-29-2010, 11:09 PM | #4 |
Registered User
Join Date: May 2009
Location: Eliot, Maine
Posts: 1,314
|
Re: 3 speed to 4 speed swap
i don't see any value in a 4 speed over a 3 speed unless it has a granny gear and you have a super soft (highway) gear in the back. a 5 or 6 speed is much better. i have the 3 on the tree in my 72 burb and the only thing it needs is an overdrive (will be fixing that evehtually w/ a vintage borg warner unit). if it had been a 4 on the floor....it would have been gone months ago in favor of a nice modern stick with an overdrive. i also like having a synchro first gear.
|
07-06-2010, 07:52 PM | #5 |
Registered User
Join Date: May 2010
Location: ambler, pa
Posts: 325
|
Re: 3 speed to 4 speed swap
Ok I have a follow up question to my initial question here guys, I picked up a 4 speed complete for $30 from a guy cleaning out his barn this week. Will a 4 speed work with a low hump 2 wd truck or do I need to swap in a high hump?
Thanks Gregg
__________________
Just would like the snow to stop so I can actually work on my truck!!!!!!!!!!! |
07-06-2010, 08:42 PM | #6 |
Registered User
Join Date: Aug 2009
Location: Alden NY
Posts: 2,705
|
Re: 3 speed to 4 speed swap
If it is a truck 4 speed you will need a high hump. Car 4 speed, like an M20 or M21, will go in with a low hump.
__________________
1961 C1 Corvette 1959 El Camino 350 TPI, 9" 4 w disc 69 Blazer K5 - sold July '20 2021 Durango RT 5.7 |
07-06-2010, 09:05 PM | #7 |
Grandpa in the rustmobile...
Join Date: Nov 2008
Location: Spokane WA/Viola TN
Posts: 11,422
|
Re: 3 speed to 4 speed swap
so is it a car one for 30 bucks!!?!?!?!?!?!??
__________________
John Goose-1968 C10 355,9.32-1CR, Vortec Heads ,262 voodoo, 3.73:1 3OTT (HS ride/beater/farm truck) http://67-72chevytrucks.com/vboard/s...d.php?t=317684 Grams 53-1953 Chevrolet Belair http://67-72chevytrucks.com/vboard/s...=1#post4327784 1969 Chevy C10 Shortbed 4.5/6?" Frame off resto http://67-72chevytrucks.com/vboard/s...d.php?t=548136 1999 Toyota Tacoma 4x4 |
07-06-2010, 09:41 PM | #8 |
Registered User
Join Date: May 2010
Location: ambler, pa
Posts: 325
|
Re: 3 speed to 4 speed swap
Its a truck one.....oh well guess Im puttin a hump in
__________________
Just would like the snow to stop so I can actually work on my truck!!!!!!!!!!! |
07-14-2010, 04:42 PM | #9 |
Registered User
Join Date: May 2010
Location: ambler, pa
Posts: 325
|
Re: 3 speed to 4 speed swap
Ok I swear this is my final follow up question......can I use my 3 speed beel housing or is the 4 speed one different?
Thanks again guys
__________________
Just would like the snow to stop so I can actually work on my truck!!!!!!!!!!! |
07-14-2010, 07:57 PM | #10 | |
Registered User
Join Date: Mar 2003
Location: San Francisco, CA USA
Posts: 2,454
|
Re: 3 speed to 4 speed swap
Quote:
http://dennymac.com/mod.php?mod=user...103&page_id=54 Ray |
|
07-23-2010, 09:29 PM | #11 |
Registered User
Join Date: May 2010
Location: ambler, pa
Posts: 325
|
Re: 3 speed to 4 speed swap
One more question can I reuse my 3 speed driveshaft or is the 4 spd a differnt length
__________________
Just would like the snow to stop so I can actually work on my truck!!!!!!!!!!! |
07-23-2010, 11:11 PM | #12 |
Registered User
Join Date: Aug 2009
Location: Alden NY
Posts: 2,705
|
Re: 3 speed to 4 speed swap
The truck 4 speed sm465 has a yoke bolted to the tailshaft much like the yoke on the differential. A two piece drive shaft is used because the sliding portion is on the rear section after the carrier bearing. I think the 4 speed truck transmission is shorter than the 3 speed. I have one of each out of vehicles but didn't measure so I am not absolutely positive. In any event, the driveshaft, if a two piece will have to have a u joint that adapts to the bigger transmission yoke and your driveshaft front yoke and it may need the front tube lengthened. If you are going to use the truck 4 speed, you will need the 2 piece shaft. A car 4 speed, like an m20 or m21 is pretty close in length to the 3 speed, but will need a fine spline slip yoke for the transmission (27 I think) as opposed to the 11 spline yoke on your 3 speed. The drive shaft, if I remember correctly, had to be shortened slightly on my 66 which was a 3 speed with a one piece shaft.
__________________
1961 C1 Corvette 1959 El Camino 350 TPI, 9" 4 w disc 69 Blazer K5 - sold July '20 2021 Durango RT 5.7 |
07-23-2010, 11:19 PM | #13 | |
Registered User
Join Date: Mar 2003
Location: San Francisco, CA USA
Posts: 2,454
|
Re: 3 speed to 4 speed swap
Quote:
Long answer: The 4 speed shaft is longer than the 3 speed, but the main difference is in the way it is constructed. The 4 speed transmission has a yoke rigidly bolted to its output shaft. It looks something like the pinion yoke on the rear end. The front U-joint bolts to that yoke. To accommodate length changes, the 4 speed shaft has a slip joint behind the front U-joint. This slip joint serves the same purpose as the slip yoke on the 3 speed shaft, but is not interchangeable with it. Ray |
|
Bookmarks |
|
|