Rear Diff. gear change

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Aug 26, 2011 | 08:24 PM

#16

cabindoc

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From: Central NJ

OH and I had a lift on the 350 and when I started towing the 10k, I lost the lift and went to 235/75/16's because it felt a heck of a lot more stable @80mph

Aug 26, 2011 | 11:49 PM

#17

Bonanza35

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From: Norco,CA

Thanks Scott, he is not planing on towing a 80mph, but was wondering the rpm at that speed with 4.56 . What dose your 450 have, 4.88? Chet

Aug 27, 2011 | 12:01 AM

#18

SoCalSuperDuty03

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From: SoCali!!

Chet, with the 56's, and the 35's, at 80 MPH the engine will be turning 2451 RPM. The 88's are too much gear for a diesel with a 35" tire.

If he needs some ideas on a clean air bag install, I will be glad to give him some ideas. I don't like most of the commercially available mount kits.

He can check out one of my trucks and copy the brackets if he wants.

Aug 27, 2011 | 12:18 AM

#19

pjwoolw

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From: San Ramon Ca.

Chet and son if it were me towing something that large I'd be looking for a F450 or at least something with DRWs. Just my opinion but towing that big a trailer on a SRW rig isn't something I would do long term regardless of gear ratio.

Aug 27, 2011 | 08:19 AM

#20

Unrealo4

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From: Eagle Mountian, Utah

I have driven and plowed in many 04 f550's. Not sure of the gearing in those but I think they have 4.56's. They are stupidly slow and get like 13mph. Not to mention in reverse top speed is 5 mph and thats 3200rpms. I would /wrists if I had to drive one daily.

Aug 27, 2011 | 10:19 AM

#21

smokersteve

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Joined: Nov 2008

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From: CA Sacramento

here is a gear ratio chart I found.
4Lo.com :: Gear Ratio & Tire Size Chart

Aug 27, 2011 | 08:15 PM

#22

Bonanza35

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From: Norco,CA

Quote:

Originally Posted by SoCalSuperDuty03

Air bags was the first thing he did. Then engine mods, EGR, Oil cooler etc., and soon gears. Pete I agree. But its what it is for now. He goes out if luck 6 times a year, dunes and river so he's saving to find a good deal. He likes the new trucks but $$$$ for now aren't there. As I said earlier has neighbor has a 450 with 18000 miles, gear vendor etc.,

2008 wanted 50K and came over not to long ago and now 45K. My thought would be buy new for that price and the one for sale is an XL model. Chet