3spd to 4 spd conversion - The 1947 - Present Chevrolet & GMC Truck Message Board Network

deth_1970 · 07-03-2004, 05:50 AM

hello all, I have a 71 chevy, with a 3sp on the floor, i have been think seriously about installing a 4spd, thinking a muncie m22, since this will mainly be a street vehicle, a very light hauling, I personal do not think it will take much to do so, but it would be nice to hear from someone who has done this before, I am still at the planning stage of my truck, so far the only thing i have really finished is the gauges, added autometer gauges to the stock positions, and thank you all in advance

Bowtie67 · 07-03-2004, 07:28 AM

Some three speed bell housings have a smaller hole that the trans fits into, transmision should be the same length so driveshaft shouldn't need to be modified, the yoke for trans will probally be different, different shifter.

deth_1970 · 07-03-2004, 07:38 AM

so I should try to get the bellhousing and the yoke also, with then trans if i can find it used, say at a wrecking yard, or a trans shop

jlmtrout · 07-03-2004, 03:19 PM

Check the length of the two trannys from the front of the case to the end of the tailshaft to determine the need for a new driveshaft. The swap itself is straight forward. Some early bell housings were application specific, but most will accept either the 3-speed or 4-speed. Since you will need a new front yoke, if you need a new driveshaft anyway, consider a 1-piece--1 less u-joint to maintain and eliminate that pesky carrier bearing. You will have to cut the bottom of the crossmember out for clearance. I had one made out of much heavier stock by TruckPro for under $200. Also, the shifter location may be different due to the different lengths of the trannys. Good luck and keep on truckin'.......Jerry

jcueckert13 · 07-03-2004, 04:01 PM

is your current trans a 4 speed with granny gear because i was not aware of a three speed on the floor comeing stock.

deth_1970 · 07-03-2004, 05:35 PM

I asked that question in a diffrent forum, about it being stock, 3 on the floor, Im thinking it isnt, some has started re do this truck, before i got it, the steering column is clean, no hint of a shifter,

are the crossmembers diffrent for a 3 sp and a 4 spd? and I do agree going with a one piece shaft would be a better way to go, I appreciate all the input,

cableguy0 · 07-03-2004, 05:39 PM

you might want to look into a different transmission the m22 is awesome but they are very expensive to get a hold of

deth_1970 · 07-03-2004, 09:57 PM

any suggestions, on what might be just as good, and readily availible,

1972ChevyGuy · 07-03-2004, 10:02 PM

Check into the m-21 and m-20. I really like both of them.

07-03-2004, 05:50 AM	#1
deth_1970 Registered User Join Date: Jul 2004 Location: Braggs, okla Posts: 161	3spd to 4 spd conversion hello all, I have a 71 chevy, with a 3sp on the floor, i have been think seriously about installing a 4spd, thinking a muncie m22, since this will mainly be a street vehicle, a very light hauling, I personal do not think it will take much to do so, but it would be nice to hear from someone who has done this before, I am still at the planning stage of my truck, so far the only thing i have really finished is the gauges, added autometer gauges to the stock positions, and thank you all in advance

07-03-2004, 07:28 AM	#2
Bowtie67 Registered User Join Date: Jan 2004 Location: NH Posts: 2,266	Some three speed bell housings have a smaller hole that the trans fits into, transmision should be the same length so driveshaft shouldn't need to be modified, the yoke for trans will probally be different, different shifter. __________________ 1967 C10 - SWBSS Pro Street 427sbc, 700R4 & 4.10 Gears 1948 Chevy FleetMaster Coupe, LS1, (almost done) 1950 Chevy StyleLine Coupe 250/6 3x2 Dueces 2009 Toyota Tundra 1996 Harley RoadKing "I maybe getting old, but I can still burn rubber with the best of them"

07-03-2004, 03:19 PM	#4
jlmtrout Registered User Join Date: Jul 2002 Location: Memphis, Tn Posts: 194	Check the length of the two trannys from the front of the case to the end of the tailshaft to determine the need for a new driveshaft. The swap itself is straight forward. Some early bell housings were application specific, but most will accept either the 3-speed or 4-speed. Since you will need a new front yoke, if you need a new driveshaft anyway, consider a 1-piece--1 less u-joint to maintain and eliminate that pesky carrier bearing. You will have to cut the bottom of the crossmember out for clearance. I had one made out of much heavier stock by TruckPro for under $200. Also, the shifter location may be different due to the different lengths of the trannys. Good luck and keep on truckin'.......Jerry __________________ '68 c-10 long wheelbase fleetside, been in family since new, originally 250 3 speed Now (389) 350 .060 over 3.75 stroke,Edelbrock Performer RPM 70cc heads and Intake 600 cfm Edelbrock,Small Comp Cams retro-roller cam and roller rockers,9:1 cr, headers, HEI,Old Air a/c, 72 power disc brakes w/stainless lines, 3.42 gear,T-56 6-speed, original paint(what's left of it). Dakota Digital Dash

07-03-2004, 04:01 PM	#5
jcueckert13 Registered User Join Date: Apr 2003 Location: Edgewood New Mexico Posts: 2,088	is your current trans a 4 speed with granny gear because i was not aware of a three speed on the floor comeing stock. __________________ 1990 subaru legcy (daily driver) 1987 Toyota 4runner (weekend toy) 1968 C30 flatbed dually 1970 C10 longbed stepside (in pieces) 1976 Dodge Dart 1963 Dodge Dart

07-03-2004, 05:39 PM	#7
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,948	you might want to look into a different transmission the m22 is awesome but they are very expensive to get a hold of __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

07-03-2004, 07:38 AM	#3
deth_1970 Registered User Join Date: Jul 2004 Location: Braggs, okla Posts: 161	so I should try to get the bellhousing and the yoke also, with then trans if i can find it used, say at a wrecking yard, or a trans shop

07-03-2004, 05:35 PM	#6
deth_1970 Registered User Join Date: Jul 2004 Location: Braggs, okla Posts: 161	I asked that question in a diffrent forum, about it being stock, 3 on the floor, Im thinking it isnt, some has started re do this truck, before i got it, the steering column is clean, no hint of a shifter, are the crossmembers diffrent for a 3 sp and a 4 spd? and I do agree going with a one piece shaft would be a better way to go, I appreciate all the input,

07-03-2004, 09:57 PM	#8
deth_1970 Registered User Join Date: Jul 2004 Location: Braggs, okla Posts: 161	any suggestions, on what might be just as good, and readily availible,

07-03-2004, 10:02 PM	#9
1972ChevyGuy Registered User Join Date: Nov 2002 Location: Kannapolis, NC Posts: 552	Check into the m-21 and m-20. I really like both of them.

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