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#23743 05/06/2005 1:45 AM | Joined: Apr 2005 Posts: 31 Junior Member | | Junior Member Joined: Apr 2005 Posts: 31 | A buddy said I'd be better off with a saginaw 4 speed tranny if I was going for a hopped up GMC 1/2 ton, but I was wondering if there was any possibility that an old 5 speed tranny out of an old 1 -1/2 ton or some other old GMC would hook up to my 1950 1/2 ton shortbed. It does have a torque tube,...would that be a problem if it "IS" a possibility??
I just want to hop it up as if i was back in the 50s with 50s speed in mind. If that wouldn't work what would have been done say in 1954-55 on a GMC 1/2 ton shortbed??thanks in advance!
Jason | | |
#23744 05/06/2005 9:07 PM | Joined: Jun 2000 Posts: 2,773 'Bolter | | 'Bolter Joined: Jun 2000 Posts: 2,773 | If you go to Jolly's GMC page in the links section, you'll find some specs on the Clark 5 speeds. Problems with them are cost, weight, lack of spare parts, slow shifting and cost. You're talking over $1,000 for a 5 speed overdrive with synchros. Either way, you will have to lose the torque tube, best done with a differential swap at the same time. Personally, I would prefer a Muncie M-20,21 or 22, they are stronger. But my friend has a saginaw 4 speed behind his 261 and it's been strong enough for him. Even has had the tires smoking into 4th gear. 
Fred
52 3600
69 C-10
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#23745 05/07/2005 2:18 AM | Joined: Nov 2004 Posts: 122 Member | | Member Joined: Nov 2004 Posts: 122 | One thing to consider is that most of those medium-duty 5-speeds weren't overdrives. I believe some Clarks and a few Spicers had overdrive, but most were direct drive with a granny 1st gear...a granny gear would't really do anything for your performance unless you have a 12,000 RPM redline... | | |
#23746 05/07/2005 3:15 PM | Joined: Nov 2004 Posts: 22 Junior Member | | Junior Member Joined: Nov 2004 Posts: 22 | Here are the numbers for some of the Clark overdrive 5-speeds:
200VO (M) 6.06/3.50/1.91/1.00/0.80/4.87R
204VO (M) 6.06/3.50/1.80/1.00/0.80/6.00R
205VO (M) 6.06/3.50/1.91/1.00/0.80/6.00R
207VO (M) 6.06/3.50/1.80/1.00/0.86/6.00R
251VO (M) 6.06/3.50/1.80/1.00/0.80/6.00R
264VO (H) 6.06/3.50/1.80/1.00/0.80/6.00R
280VO (H) 5.98/3.50/1.86/1.00/0.80/5.04R
280VOHD (H)6.17/3.48/1.85/1.00/0.79/5.10R
300VO (H) 6.27/3.51/1.89/1.00/0.80/6.27R
380VO (H) 6.27/3.55/1.89/1.00/0.80/5.11R
400VO (H) 6.17/3.56/1.90/1.00/0.80/6.02R
The older ones, such as the 204VO and 207VO are unsynchronized, but the newer ones have at least 2-5 synchroed. They are all pretty much 4 + granny with 1st below reverse, but 1st is not nearly as low as 7.06:1 on the SM420. For regular driving you would shift it like a 4-speed, using 2nd through 5th. They also have a strange shift pattern, with 4th and 5th swapped.
As far as shifting speed, this Clark 280VOHD
[img]http://www.eskimo.com/~pparkin/truck/images/m_clark_280vo.jpg[/img]
that I'll be putting in my 1-ton has a suprisingly short throw; maybe 7 - 8" top to bottom.
All that being said, I agree that a better first step would be lower gears in the rear end. | | |
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