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Discussion Starter · #1 ·
Gents,

On my 57 with a 235 coupled with a T5 tranny, RPMs are quite high at highway speeds even in OD. What are some lower budget options to remedy?

Suggestions appreciated.

Thanks,

PW
 

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Trifive Automotive Electrical Wiring Expert
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26,959 Posts
Yup, I knew that one was coming. I suspect it's 4:11's, but what I really need to do is the pan and count the teeth.

PW
You can determine the ratio by jacking one wheel and turning it 2 revolutions while counting the revolutions of the driveshaft ( if it's a non posi rear). If one wheel won't turn (brake off, out of gear/park), it's a posi, so jack both wheels. The driveshaft revolutions is the ratio.
 

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Trifive Automotive Electrical Wiring Expert
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26,959 Posts
On my 57 with a 235 coupled with a T5 tranny, RPMs are quite high at highway speeds even in OD. What are some lower budget options to remedy?
Suggestions appreciated.
Bigger wheels. :)
 

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Discussion Starter · #7 ·
You can determine the ratio by jacking one wheel and turning it 2 revolutions while counting the revolutions of the driveshaft ( if it's a non posi rear). If one wheel won't turn (brake off, out of gear/park), it's a posi, so jack both wheels. The driveshaft revolutions is the ratio.

Ok, I just did this nifty little exercise and rotated the tire twice and came up with just shy of 4 rotations of the driveshaft, so it appears to be a 3.90:1

So is the solution to simply swap the gears to something with a lower ratio? Is that something that can be done properly without removing the rear end?

Thanks,

PW
 

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Rear End

I'd be looking on e-bay ,racin' junk.com. or local yards looking for a 3.08 or 3.31 center section if you still have a stock rear end in the car. If its a Ford look for a 3.00 or 3. 25 center section. Kinda sounds like you'll need someone to install it though.
 

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Yes the gears can be replaced and the rear rebuilt in place - but only if you are equipped. Best to have a shop do it so you are back to taking them the rear or the whole truck.
 
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