UPGRADE DIFFERENTIAL RATIO

1994 Cadillac Fleetwood

Tiny

94fleetwood

August, 29, 2011 AT 12:22 AM

Hi, I am planning on using my 94 Cadillac Fleetwood to tow a camper trailer. The diff. Ratio it has is at 2.56: 1 (not the best towing ratio).
I plan on upgrading to a 2.93: 1 (from a Brougham) to increase the towing capacity to 5000lbs. Will this affect the pcm? Is there a tuning that must be done to the chip?

FOUND 176 RELATED QUESTIONS

4 Answers

Tiny

mhpautos

August, 29, 2011 AT 2:03 AM

No change there is required, but with the different diff ratio you will get an inaccurate speedo reading, you may be able to change the speedo drive to one for a model with that ratio.

Tiny

94fleetwood

August, 29, 2011 AT 2:08 AM

Thanks for your input. The car has 235/75/15 tires on. Originally, it should run on 235/70/15. Would this slight difference in tire size compensate the speedo difference a little?

Tiny

cadieman

August, 29, 2011 AT 9:30 PM

Their is about 4 to five gears with different teeth nunbers. Make sure you have a good tranny cooler and a heavy duty radiator if possable. Thanks for using 2carpros

Tiny

mhpautos

August, 29, 2011 AT 10:28 PM

It is only the dia of the trye that will alter spedo readings, both are 15" so ther is no differance there.

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