I have a 2008 Sahara Unlimited with 100,000 miles, automatic and recently put a set of 18" XD Spy's and Toyo 35x12.50 and its really struggleing on hills and accelerating. I noticed a slight howling sound thinking it's the torque converter around 25-30 mph in 2nd gear. I really dont want to spend $1500 re-gearing so I'm considering the AEV Procal. Will it make a big difference? I understand it helps the speedo which Im not really concerned with.. If not, I may just put the factory wheels back on and sell the Spy's...

 

you know it's the tires fault and not the wheels right?

 

A procal will fixtures speedo, but ur struggling due to the tire size... But u don't NEED to regear.... I had a 2010 JKU Sahara with factory 3.73's and 37X12.50R18 BFG KM2 tires, it struggled a bit but it was okay and I was running those same wheels

 

Here's a pic

 

It will bring back your shift points back to factory like which will help if you do a lot of wheeling then I think it's good to regear but if its a DD then just use procal I felt a small diff and I'm happy with it mines a 2010 17' rims with 285/79/17 toyo open country tires

 

I am considering the ProCal as well, but would it really make any difference with a manual??? Other than the speedo?

 

chase17- Pro cal will recalibrate your speedometer and shift points on an auto but won't change your torque. Turn overdrive off so the rpms are around 2700 to 3000. I have the 3.8 auto with 4.10s so I feel your pain. Have you serviced your transmission?

 

The auto shifts at certain rpm/ load / throttle positions. Changing tire size throws everything off, and confuses the computer. Manual transmissions use the best computer to switch gears, that's you. But the Procal can pay for itself by avoiding a speeding ticket.

 

U always turn off the O/D.. I think I might just put the stock 18" back on with some nice 285/70's..

 

Oops, I meant to say I always turn the O/D off