transmission options? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

hpcgmc · 11-05-2012, 11:28 AM

My 67 GMC has the four speed granny. I think I'd like to keep manual trans, so what are my options? Can I have this 4 speed rebuilt with higher gears, and if so, is it really expensive? Is there an easy 5 speed swap? I'm not good at fabricating, so I'll probably need a kit for anything that requires fabricating.

If I decide to go with an auto trans, how difficult is the changeover from manual to auto trans?

Thanks!

RustyBucket · 11-05-2012, 01:52 PM

I don't think there's any way to rebuild your transmission and have an overdrive top gear... still gonna be 1 to 1 ratio. PO installed a TKO 500 in my Blazer with a kit from Keisler. Converted from a 350 turbo to an O.D. 5spd. BIG FUN rippin' through the gears!!... 80mph at 2000 RPM cruise, 15mpg. Downside is $2500++ kit price.

**Tom Vogel** · 11-05-2012, 06:19 PM

Quote:

Originally Posted by RustyBucket

I don't think there's any way to rebuild your transmission and have an overdrive top gear... still gonna be 1 to 1 ratio. PO installed a TKO 500 in my Blazer with a kit from Keisler. Converted from a 350 turbo to an O.D. 5spd. BIG FUN rippin' through the gears!!... 80mph at 2000 RPM cruise, 15mpg. Downside is $2500++ kit price.

^^^ X2 a very valuable upgrade

arocars · 11-06-2012, 06:18 PM

It sounds like you want more performance. If that's the case, I would start with the rear end and leave the trans alone. You are not going to realize much of a difference by reworking the transmission. Also, if you have a standard trans and know how to drive it, leave it. Dont swap to an auto. Its just not worth the money. There is no substantial performance gain there either.

SS Tim · 11-06-2012, 07:15 PM

Look for a used Gear Vendors O/D unit. It will give the top gear boost keep the deep first give a clutchless 1up gear shift and help keep in the 283's powerband. Saw one for a $1000 on the SF CL. Go to their site and look about and see how your truck 4-speed can be a usable 8-speed. www.gearvendors.com

hpcgmc · 11-06-2012, 09:35 PM

Thanks for the ideas and info. Although I'd love a 5 speed trans, $2500 is out of my budget. My trans has 180k miles on it, the synchros are going out, and I found a big chunk of something in my trans the other day (a trans guy said it looks like 1/4 of one of my synchros). So, I need to rebuild or replace this trans. I don't want the granny gear, since this won't be much of a work truck anymore. Could I have the trans rebuilt with a higher first gear?

I'll be replacing this rear end (low geared out of 3/4 ton truck) with a higher rear end from a 1/2 ton soon, so that should help out on the highway - I'm hoping that will drop drop the rpm from 2500 rpm at 55 mph to 2500 rmp at 65 or 70, if I keep taller tires. I dont' have the gear ratios for either of these rear ends. It still leaves me with the too low granny gear.

I like the idea of the overdrive unit -is that basically like the old 2 speed rear ends in heavy duty trucks - you can shift into low or high from any of your trans gears? I could always add that if needed.

Oh, and the 283 will be pulled eventually and replaced with a lightly built 327 or 350, so I should have more torque.

**jocko** · 11-06-2012, 09:45 PM

I was about to suggest a T5 until you said you plan to pull the 283 and plan to add a 327 or 350. If you drive sanely - T5 is still an option - but it's NOT for towing, and NOT for racing, and NOT for burnouts, etc. But it IS a very cool little trans. Again, don't recommend if you plan to do burnouts with that 350... But if interested, here's the install details in a 66, procedure and info applies. http://67-72chevytrucks.com/vboard/s...d.php?t=482069 T5 has a relative deep 1st gear (but not granny-deep... around high 3's to low 4's (depending on what it came out of) and a reasonable o/d gear.

hpcgmc · 11-07-2012, 11:22 PM

Umm, drive sanely? No burnouts? No towing? No racing around? I guess a T5 isn't for me. Whats the next sturdier trans? I won't have tons of power, and wont be towing much, but I'm sure I'll be driving it hard on occasion. Will a T5 or something similar bolt right in to replace the stock trans, or will I need to fabricate mounting brackets, etc?

RustyBucket · 11-08-2012, 12:26 AM

http://67-72chevytrucks.com/vboard/s...d.php?t=482069

This link from jocko's post is a VERY detailed description of a T5 installation. Good stuff!

chvtrkman · 11-09-2012, 11:29 PM

You may want to consider a GM MY6 4 spd. OD tranny. I put one in my '69 C-20 5 or 6 yrs ago and I like it a lot. It should handle the horsepower you want to
run through it. Here is an old thread about it: http://67-72chevytrucks.com/vboard/s....php?p=3895102

11-05-2012, 11:28 AM	#1
hpcgmc Registered User Join Date: Oct 2012 Location: Northern Cal Posts: 249	transmission options? My 67 GMC has the four speed granny. I think I'd like to keep manual trans, so what are my options? Can I have this 4 speed rebuilt with higher gears, and if so, is it really expensive? Is there an easy 5 speed swap? I'm not good at fabricating, so I'll probably need a kit for anything that requires fabricating. If I decide to go with an auto trans, how difficult is the changeover from manual to auto trans? Thanks! __________________ 1967 GMC 1500 SWB. Driving this truck since I was 14.

11-05-2012, 01:52 PM	#2
RustyBucket Registered User Join Date: Jul 2009 Location: Space Coast, Fl. Posts: 1,050	Re: transmission options? I don't think there's any way to rebuild your transmission and have an overdrive top gear... still gonna be 1 to 1 ratio. PO installed a TKO 500 in my Blazer with a kit from Keisler. Converted from a 350 turbo to an O.D. 5spd. BIG FUN rippin' through the gears!!... 80mph at 2000 RPM cruise, 15mpg. Downside is $2500++ kit price. __________________ Dad always said, "Son, WISH IN ONE HAND, and ......." -------------------------------------- -------------------------------------- Current toy trucks: '71 GMC 1500 SUPER CUSTOM short/step, orig. dk. blue, 350/700r, ps,pb, A/C '72 Blazer 2wd, ochre & white, 454, tremecTKO 500 5spd. ps, pb, A/C, tilt Last 10yrs of hobby vehicles, had a FEW more in the 50yrs. before these: '66 Plymouth Belvedere City of Miami cop car clone. '70 Nova 406"sb, 13.5-1, solid roller, Brodix, p.glide/t.brake, back halved, 9" Ford, spool 4.88, cage,ladder bar/coilover, 10.5 tire....... SOLD!! '67 C10 short/step side mount spare -- SOLD!! '72 Jimmy 2wd, 350/350, ps, pb, fun driver, lots of bondo & a shiny red paint job..... SOLD!! '69 Nova 350, 4spd, A/C, ps, p.b, ...SOLD!!

11-06-2012, 06:18 PM	#4
arocars Registered User Join Date: Dec 2010 Location: Taunton, Massachusetts Posts: 26	Re: transmission options? It sounds like you want more performance. If that's the case, I would start with the rear end and leave the trans alone. You are not going to realize much of a difference by reworking the transmission. Also, if you have a standard trans and know how to drive it, leave it. Dont swap to an auto. Its just not worth the money. There is no substantial performance gain there either.

11-06-2012, 07:15 PM	#5
SS Tim Registered User Join Date: Aug 2010 Location: Edwards, CA Posts: 7,503	Re: transmission options? Look for a used Gear Vendors O/D unit. It will give the top gear boost keep the deep first give a clutchless 1up gear shift and help keep in the 283's powerband. Saw one for a $1000 on the SF CL. Go to their site and look about and see how your truck 4-speed can be a usable 8-speed. www.gearvendors.com __________________ Thanks, Tim * VIN/Model Decoders * Power Team Charts (engine/transmission/gear ratio) * Post Your Pickup SPID Blazer SPID Suburban/Panel SPID * RTFM ... Read The Factory Manuals... download 'em here Highlanders Do you have a 1972 Plaid Pickup? Plaid Blazer ** Plaid Suburban

11-06-2012, 09:35 PM	#6
hpcgmc Registered User Join Date: Oct 2012 Location: Northern Cal Posts: 249	Re: transmission options? Thanks for the ideas and info. Although I'd love a 5 speed trans, $2500 is out of my budget. My trans has 180k miles on it, the synchros are going out, and I found a big chunk of something in my trans the other day (a trans guy said it looks like 1/4 of one of my synchros). So, I need to rebuild or replace this trans. I don't want the granny gear, since this won't be much of a work truck anymore. Could I have the trans rebuilt with a higher first gear? I'll be replacing this rear end (low geared out of 3/4 ton truck) with a higher rear end from a 1/2 ton soon, so that should help out on the highway - I'm hoping that will drop drop the rpm from 2500 rpm at 55 mph to 2500 rmp at 65 or 70, if I keep taller tires. I dont' have the gear ratios for either of these rear ends. It still leaves me with the too low granny gear. I like the idea of the overdrive unit -is that basically like the old 2 speed rear ends in heavy duty trucks - you can shift into low or high from any of your trans gears? I could always add that if needed. Oh, and the 283 will be pulled eventually and replaced with a lightly built 327 or 350, so I should have more torque. __________________ 1967 GMC 1500 SWB. Driving this truck since I was 14.

11-06-2012, 09:45 PM	#7
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,976	Re: transmission options? I was about to suggest a T5 until you said you plan to pull the 283 and plan to add a 327 or 350. If you drive sanely - T5 is still an option - but it's NOT for towing, and NOT for racing, and NOT for burnouts, etc. But it IS a very cool little trans. Again, don't recommend if you plan to do burnouts with that 350... But if interested, here's the install details in a 66, procedure and info applies. http://67-72chevytrucks.com/vboard/s...d.php?t=482069 T5 has a relative deep 1st gear (but not granny-deep... around high 3's to low 4's (depending on what it came out of) and a reasonable o/d gear.

11-07-2012, 11:22 PM	#8
hpcgmc Registered User Join Date: Oct 2012 Location: Northern Cal Posts: 249	Re: transmission options? Umm, drive sanely? No burnouts? No towing? No racing around? I guess a T5 isn't for me. Whats the next sturdier trans? I won't have tons of power, and wont be towing much, but I'm sure I'll be driving it hard on occasion. Will a T5 or something similar bolt right in to replace the stock trans, or will I need to fabricate mounting brackets, etc? __________________ 1967 GMC 1500 SWB. Driving this truck since I was 14.

11-08-2012, 12:26 AM	#9
RustyBucket Registered User Join Date: Jul 2009 Location: Space Coast, Fl. Posts: 1,050	Re: transmission options? http://67-72chevytrucks.com/vboard/s...d.php?t=482069 This link from jocko's post is a VERY detailed description of a T5 installation. Good stuff! __________________ Dad always said, "Son, WISH IN ONE HAND, and ......." -------------------------------------- -------------------------------------- Current toy trucks: '71 GMC 1500 SUPER CUSTOM short/step, orig. dk. blue, 350/700r, ps,pb, A/C '72 Blazer 2wd, ochre & white, 454, tremecTKO 500 5spd. ps, pb, A/C, tilt Last 10yrs of hobby vehicles, had a FEW more in the 50yrs. before these: '66 Plymouth Belvedere City of Miami cop car clone. '70 Nova 406"sb, 13.5-1, solid roller, Brodix, p.glide/t.brake, back halved, 9" Ford, spool 4.88, cage,ladder bar/coilover, 10.5 tire....... SOLD!! '67 C10 short/step side mount spare -- SOLD!! '72 Jimmy 2wd, 350/350, ps, pb, fun driver, lots of bondo & a shiny red paint job..... SOLD!! '69 Nova 350, 4spd, A/C, ps, p.b, ...SOLD!!

11-09-2012, 11:29 PM	#10
chvtrkman Registered User Join Date: Sep 2007 Location: PA. Posts: 178	Re: transmission options? You may want to consider a GM MY6 4 spd. OD tranny. I put one in my '69 C-20 5 or 6 yrs ago and I like it a lot. It should handle the horsepower you want to run through it. Here is an old thread about it: http://67-72chevytrucks.com/vboard/s....php?p=3895102 __________________ _____________________________________________ 69 C-20 292, 4 spd O/D, 4:56 rears. No a/c p/s p/b p/w......restoration project,"Operation:Stovebolt" 78 C-10 305 TH350 new (old) daily driver 02 Suburban Z71 a.k.a. the family truckster 99 Silverado 1500 Z71



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