06-21-2003, 09:42 PM | #1 |
Registered User
Join Date: Jun 2003
Location: s.e. tenn
Posts: 28
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drivetrain swap
I have a 71 k-5 with 307 and 3-speed on the the column. I just bought it a few months ago. I think it's great but my problem is when I tow a trailer it doesn't have a low enough 1st gear. I am pulling a med. trailer with atvs. I would like to swap to a 4-speed but I don't know how hard it would be. The owners manual list 2 diffrent 4-speeds. The 465 and the np-435. It also list the ratios of them. I think the 435 has the better ratios for what I need. I know it would help towing. The truck runs good with the combo I have now and I hate to tear into it. It just doesn't pull a load well. The transfercase is a Dana 20. 4-speed and auto trucks came with 205's. So if I swap will I have to go to a 205 as well? Would an engine making more torque and the three speed work? I don't know what the rear gears are. On the highway it does about 2200 rpm at 60 mph. I'm thinking 3:08 but somethings I have read say blazers came with 3:73's. Any suggestions would be appreciated.
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06-21-2003, 10:16 PM | #2 |
Registered User
Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,723
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Get a complete 465/205 combo. It is excellent for trailering. The 435 in a 4 wheel drive is REALLY uncommon, but the 465/205 combo can be found well into the 80's.
2200 sounds just like 3.08. You could switch to 3.73 or so, but you would have to do both ends, and it would negatively affect your cruise rpm but help with towing significantly. I vote for the 4 speed and keeping the 3.08, assuming you are running stock size tires. If you go to 31s, you really need 3.42, 3.73 for 33s, and 4.10 for 35s. My Jimmy worked pretty well with the stock 350 motor, 3.07 and the 465. It was a dog with the big cam, 33's and the 3.07 however... Great again with a little cam and 4.10 turning the 35s.
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06-21-2003, 11:56 PM | #3 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Might be easier to swap in an engine with more low end grunt,a nd leave the tranny/transfer alone.
More torque will walk right over the poor gearing. |
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