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Fix It Man
Fix It Man, Master Technician
Category: Ford
Satisfied Customers: 17171
Experience:  ASE Master Certified, AA Degree Auto/Diesel
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95 f350: over size tires..effect trans..power stroke..overdrive

Customer Question

can over size tires 37x12.50x16 effect trans on a 95 f350 power stroke causing transmission to come in and out of overdrive? If so, what would be the proper fix. can ecm be reprogrammed? also, diff gears are 4.11 ratio.
Submitted: 4 years ago.
Category: Ford
Expert:  Fix It Man replied 4 years ago.

Fix It Man :

Hello JACUSTOMER, this will definitely cause this problem. You need to change the gears to a lower gearing and install a computer piggy back unit that will allow you to change the gearing calibration in the computer for transmission shift points.

JACUSTOMER-cpjcgzao- :

what ratio would be the right one and whom do you suggest on this piggy back unit.?

Fix It Man :

I believe that jet chip still makes the piggy back for this truck. They are getting harder to come by. As for the ratio do you tow with the vehicle? Is it a dually?

JACUSTOMER-cpjcgzao- :

It is not a dually, and yes a 30 ft. travel trailer. what inputs are affecting the ecm, tps, vss what exactly is happening?

Fix It Man :

The VSS is what affects it. It needs to know the actual speed of the vehicle and with the larger tires it will be way off. I would at the very minimum go to a 4:53. I would really recommend a 5:13. If you put in the gears then you really do not need the piggy back unit.

JACUSTOMER-cpjcgzao- :

Fix It Man thank you very much, but I have just one more question, can I use the piggy back and approximately how much do they run, and what off road place or performance company do you recommend, sorry i meant a few more questions. Thank you

JACUSTOMER-cpjcgzao- :

can I use the piggy back only without the gears?

JACUSTOMER-cpjcgzao- :

can the transmission be damaged, and will it be best to drive it out of overdrive? and what kind of problem could I have? If I were to not use the piggy back or gear reduction solution, money is a factor. Thank you again.

JACUSTOMER-cpjcgzao- :

I will click on accept after you answer these few questions. Thank YOu. again

Fix It Man :

The piggy back option is a band aid and it definitely not the best repair. The best repair is the gearing. If you do not do this then you will damage the transmission and even the rear differential over time. If you take it very easy on the vehicle when it comes to acceleration and towing then you can do without for a while.

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