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Discussion Topic:
Changing rear end ratio
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voced |
01-07-2015 @ 2:51 PM
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Member
Posts: 86
Joined: Oct 2009
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I have a 2:78 ring and pinion (I think out of a 46) to put in my 35 pickup that has a 4:11. After getting it apart I notice that the number of pinion splines are not the same and the carrier bearings are larger on the 2:78. What can I do to make this work? Jerry
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Stroker |
01-07-2015 @ 3:15 PM
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Senior
Posts: 1460
Joined: Oct 2009
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I'm thinking that you actually have a 3.78:1 gearset, as 2.78 is not a Ford ratio. Having said that, I'd look for a compatible earlier 3.78 gearset. Here's a link to all the differences between years: http://www.flatheadv8.org/fordrear.htm
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ken ct. |
01-07-2015 @ 3:16 PM
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Senior
Posts: 1513
Joined: Jan 2010
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You will not be happy with a 2.78 RE in a flathead.Not enough motor to pull that ratio.Dont believe FH's came with that low a ratio. 3.78 would be much better. ken ct.
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ford38v8 |
01-07-2015 @ 3:50 PM
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Senior
Posts: 2762
Joined: Oct 2009
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Use the later center section, and a 6 to 10 tooth spline adapter.
Alan
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voced |
01-07-2015 @ 5:12 PM
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Member
Posts: 86
Joined: Oct 2009
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Yes I meant it is a 3:78 not 2:78 Sorry
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MICHV8 |
01-08-2015 @ 6:25 AM
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Member
Posts: 437
Joined: Jul 2010
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Stroker... What a great article! Thanks for posting the link. What is different about 33-34 axles? The author briefly mentions the narrow center section, but doesn't seem to go into detail like the other years...
This message was edited by MICHV8 on 1-8-15 @ 6:29 AM
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Stroker |
01-08-2015 @ 2:24 PM
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Senior
Posts: 1460
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MICHV8: I don't have any personal experience with 33-34 axles, so I can't address your question. I'm sure there are many Forum members who can enlighten both of us. As for the link, I should give credit to Golden Gate RG#1, as that's where I sourced it. Many of our Regional Groups have great tech links, and you can source them right here on this site. vocd: I believe you would be better for you to find a ca 33-34 gearset as 3.78:1 was a common ratio even then. The Green Book may help with compatibility/interchange issues.
This message was edited by Stroker on 1-8-15 @ 2:29 PM
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voced |
01-08-2015 @ 6:26 PM
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Member
Posts: 86
Joined: Oct 2009
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The rear end is in my 1935 pickup. It also has the large inside pipe type drive shaft (not the solid shaft type)and not sure how a 10 to 6 spline adapter will work. Also, do any of you know what type speedometer gears I will need for the 3:78 ratio.
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ford38v8 |
01-08-2015 @ 9:35 PM
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Senior
Posts: 2762
Joined: Oct 2009
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I think a spline adapter would have to be welded onto a hollow shaft, not sure on that. #3.78 gearing would take a 19 turtle gear.
Alan
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40 Coupe |
01-09-2015 @ 4:12 AM
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Senior
Posts: 1676
Joined: Oct 2009
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The 10 spline pinion is typical of the late 32 & 33-34 fords. I am sure it may have been carried over to 35. I believe someone is making an adapter from 10 to 6 spline, try the stores that specialize in the gearing. The 10 spline pinion is slightly shorter than the 6, your drive shaft may have to be shortened. You will have to use the bearings for the 10 spline so the diameter of the 6 spline pinion has to be reduced and you need a spacer for the threads. The gear head of the 3:78 is too large to pass through the differential case so the case can be opened slightly or the OD of the gear head reduced to pass. Some of the cases have slight interference to the 3:78 ring gear which can be ground out.
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