Pulling a camper

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May 14, 2012 | 11:45 AM

#61

Fordzilla80

Logistics Pro

Joined: Jun 2008

Posts: 4,990

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From: Florida

Quote:

Originally Posted by budford

I guess I have one of the odd F-100's since mine has the F-150 class brakes. It's a 4700 lb rated short bed built in Dec. of 1980.

If it has manual brakes, then that's why. All F100's with manual brakes received the F150 stuff.

If your truck has power brakes, I have heard of a few exceptions, although I can't answer why Ford did it that way.

May 14, 2012 | 02:54 PM

#62

kedwinh

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Joined: Jun 2004

Posts: 1,092

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From: Casa Grande

Quote:

Originally Posted by 1986F150six

For the original poster... if you change from the original 2.47 to a 3.55 differential, that is a 43.72% change which is huge [ask me how I know]. Your speedometer will indicate 79 mph @ a true 55 mph.

My son's truck with like change is definitely much more fun to drive and lost about 2-4 mpg on the interstate.

That's exactly what was done with mine. Don't know the MPG change but, it is easier to drive. I've thought that a 3.08 would be a good compromise if towing wasn't important.

May 14, 2012 | 03:14 PM

#63

1986F150six

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Joined: Jul 2009

Posts: 6,477

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From: Sheffield, AL

Quote:

Originally Posted by kedwinh

That's exactly what was done with mine. Don't know the MPG change but, it is easier to drive. I've thought that a 3.08 would be a good compromise if towing wasn't important.

I have owned all three [2.47, 3.08 and 3.55] and feel that the 3.08 seems to be happier at the 65-75 mph range as the engine does not get as "tight". The 3.55 is peppier and more fun in town. The 2.47 can deliver excellent gas mileage on the highway.

I think my ideal ratio with the SROD transmission, which all three examples had, would be what was offered in the 9" differential... 3.25.

May 14, 2012 | 04:38 PM

#64

82f100460

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Joined: Jan 2012

Posts: 1,410

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From: Dallas, GA

Quote:

Originally Posted by kedwinh

That is a cover, like a dana44 or 10 bolt, just different shape. They bolt onto the rear of the diff just like the others do. Think the Ford 9" is the only one with a removable pumpkin. Most all other diffs have a axle mounted pinion/gear/axles and a removable cover to service/change fluid. Unless I'm not understanding what your saying, which is REAL possible.

But either way, he's got some work to do if he wants to safely pull anything. I helped my friend swap rear ends on mine before I bought it from him. It had the same setup I think this guy has and it would hardly get out of it's own way empty. SROD 4sp and 2.47 gear even with the factory 215/75 tires is geared way high.

Yep....you are absolutely right!!! I had 9" in my head the whole time while we were discussing an 8.8. I was thinking of my F100 that has the 9". For some reason I thought the earlier 8.8" were like the 9" with the removable carrier.