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02-26-2010, 10:53 PM | #1 |
Registered User
Join Date: Nov 2009
Location: San Antonio TX
Posts: 251
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Need help ring and pinion
I read most threads discussing ring and pinion changes but I can't seem to get a good understanding of what is needed. I have a 69SWB with a 250 and muncie three speed on the column with 3.73 rear. I want to change R&P to a 3.08 for better highway use. Majority of my driving is cruising. I found a 3.08 RR in 1971 C10. Being that I want to keep the 6 lug and my axle is 1" shorter then a 1971, I can't swap rear ends. Can I do a swap from one to the other? Using the rpm calc, 70x3.73x1x336/31=2829rpm. If I go with a 3.08 R&: 70x3.08x1x336/31=2336rpm. Thats a 500rpm reduction at 70mph. Any opinions would be great.
thanks louis |
02-27-2010, 12:25 AM | #2 |
Cops, ha, catch me if you can!
Join Date: Jun 2009
Location: Santa Barbara, CA.
Posts: 271
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Re: Need help ring and pinion
You might want to think about getting an OD tranny, like a 200R4 or a 700R4, not sure if they will fit with your engine though. If not upgrade to a 350 and a 700R4.
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72 C-10 Stepper 350/TH350 3.73 in the back Edelbrock intake and Carb Hooker Comp Headers 275/60R15 on Rallies |
02-27-2010, 08:21 AM | #3 | |
just can't cover up my redneck
Join Date: May 2004
Location: Columbus OH
Posts: 11,414
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Re: Need help ring and pinion
I assume that "swap from one to the other" means swapping the gears from one housing to the other?
If so, that is a "qualified" yes. They will physically fit.....but it is not a good idea. Installing used gears is more difficult than new and you are still "playing with fire". Many professionals will not even do it. A new set is not going to cost you that much more than buying an entire axle just to get at the used gears inside. Buy a new set and pay a professional to install them. You get a warranty, peace of mind, and a lot less hassle.
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02-27-2010, 08:26 AM | #4 |
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Re: Need help ring and pinion
i dont think there'd b much gas saving with that combe due to how hard the 6 needs to work getting up thru the gears
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02-27-2010, 08:51 AM | #5 | |
Six in a row makes it go...
Join Date: Mar 2009
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Re: Need help ring and pinion
Quote:
I've done it to two trucks now (3.73 to 3.07). You get a minor gain in mpg. An overdrive transmission would probably buy you more.
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02-27-2010, 08:55 PM | #6 |
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Join Date: Nov 2009
Location: San Antonio TX
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Re: Need help ring and pinion
I spent all day today searching junk yards and talking to many people about what I am trying to achieve. Most made the same comments you guys have. I decided I will go with an early model NP440 (A833/MY6/NP833) 4 speed manual with OD. Looks as the gear ratio are close to the 700R and it gives me a final rpm of 2000prm @70 with my combo. Being I currently have a 3 speed saginaw, it should be a quick swap other than the floor shift install. I found two today. Both rebuilt with shifter for $700 ans $550. Going to take the plunge. I was going to buy used 20" boss 315, but that wont be till next month if they are still in the paper.
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02-27-2010, 09:17 PM | #7 | |
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Join Date: Jan 2007
Location: Topeka,KS
Posts: 778
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Re: Need help ring and pinion
Quote:
When you set your gear's wear pattern with the blue dye I would try to match it more with wear pattern that's already on the gears than to spec. I would also use the shims from the 3.08 pinion and carrier. And see where that gets you first. Last edited by airdale94; 02-27-2010 at 09:26 PM. Reason: add |
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