E4od/4r100

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Feb 5, 2009 | 09:20 AM

#16

krewat

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From: Long Island USA

Quote:

Originally Posted by SLE

I don't want to hijack this thread but it seems as though I finnally found someone that knows the differences. My questions is I'm trying to figure out why my 03' 4R100 with 373's and 16" 285s turns a ton of rpms less then my dads 93 7.5L F350 2wd dually with 4.10's and of course a smaller tire. I know his will turn more rpms but the difference is like 1200 rpms when we are each in the same gear, so something doesn't make sense unless the trany gears are considerably different ratios which I thought the E4OD and the 4R100 used the same ratios???? The only thing I cann't remember for sure is his tire size but it seems to me that it's a 16" 245, but I could be wrong! any ideas?

Are you sure he's shifting into overdrive at all? Or that the TC is locking up?

Or does he REALLY have 4.10's? Sure it wasn't changed to something else? Might be worth checking by hand.

Feb 5, 2009 | 10:00 AM

#17

SLE

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From: North Dakota

yeh, I'm sure his tranny is shifting though all the gears and locking-up like it's suppose to. Matter of fact the tranny had a rebuild not so long ago although that changed nothing more than firmer shifts and got rid of the shudder! I personally think that either the tach is not right or the gears were changed because at 70mph in OD/4th he's running around 3k rpms! Heck I'm not even at 3k rpms in 3rd at 70! Any idea what tire size would have came on a 93' F350 2wd Reg Cab XLT Dually?? He has the original build sheet that lists 4.10s so thats what he's going by. I should probably jack it up and check the true ratio.

Feb 5, 2009 | 11:17 AM

#18

dkf

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From: Pa

Man hes running way up there in rpm at 70mph. I'm just under 2krpm at 70 with 3.73s with my SD. I would check the ratio out. The the rpm hes turning it almost seems like hes got 4.88s, 4.88s and smaller dia 245s would bring the rpm up. At least hes got a 2wd so he doesn't have to mess with two axles. Usually when a tach is off its way off, its more unlikey the tach is off if the tach shows the truck is idling at the proper rpm.