I have just had new gears put into my '93 F150 4x4 and have a bit of a situation. When I went to the shop to order up the gears I explained my desire to return my vehicle to stock as I am running 33's. I told the shop that I was not a rockcrawler and actually found that stock tires made the gear's a little short for my preferences. The gear ratio that I thought was in the vehicle was 3.55 as this is what the diff tag and a call to Ford Can. had turned up. 4.10's were ordered and the big(expensive)day arrived. When I pickup up the vehicle and drove away I immediately noticed the changed gearing in the vehicle and thought there must be some mistake as at 35 miles an hour I was able to switch to 5th gear with no lugging. I was wondering if perhaps 4.56's had been put in by mistake. I called the shop that did the work and was told that my vehicle had 3.08's, not 3.55's to begin with. I did not recieve a phonecall during the work and they must have noticed upon disassembly that the stock gears were not as expected.

Does anyone feel that the shop has some responsibility in this and should help cover the costs in rectifying the situation? It would require redoing the whole job basically to put in the 3.73 ratio that would more or less return my vehicle to factory. And there is a complicating factor of a Dana 44 TrueTrac that will not work with the lower ratio(3.73).

Your comments and opions are appreciated.

 

Picking the correct gearing to use for the specified application is a difficult thing to do, I know from experience. Before I decided on what gears I was going to put in I did my homework: checked the RPM per MPH, verified the gear ratio by physically turning the axle and counting the rotations of the drive shaft, and finally mathed-out the engine speed in relation to anticipated speeds in different gears and buying the correct speedo gear. And, as it turned out, I was geared higher than I'd really wanted be. But the gear shop had done what I'd asked them to do, so it was my problem - not theirs. Looks like you are in the same boat. :-( I don't see where they had any obligation to call you when they took it apart to tell you that you were making a mistake. You, as a customer, told them to put in 4.10 gears and that's what they did. I made the best of my situation by changing to a tire with a more compatable aspect ratio to compensate. Lesson learned.

 

whaynes,
I'm really surprized that you are unhappy with your new gears. The 4.10's with 33's and overdrive should put the RPM's right where they should be. I've got 4.56's in my truck with 33's and I love it. It's street driven only, I have 5.38 gears in my rockcrawlers. Also, you must remember that unless you recalibrated your speedometer for the larger tires, you are going faster than what it says. No recal is needed for the gearswap because the speed sensor is on the ring gear.
I think vanman is right about the liability issue. Basically they only did what they where told. By the way, your limited slip carrier will work with the 3.73's if it's in the 8.8 rear.

Later,
Jon

 

Thanks for your replies.

I do know that I need a speedo gear for the tires but have not got around to it yet. I believe the difference is around .14 for my tire upgrade. The 4.10's are not all bad but gas mileage and highway driveability are concerns(Gears have only been installed for a week) I could go with 35's but feel that there will be impacts to suspension and the TrueTrac with a larger, heavier tire.

My feeling as to responsibility for the end result is that I do share a portion. But changing the gears is a big propisition which I did research but in the end I also depend on the advice and knowledge of a "qualified" shop with experience in this type of venture. When time permits I always try to make myself available onsite or by phone when shops have my vehicle in for repair but in this case that was not possible. When the gears were ordered I was quite explicit that the plan was to return to stock. 4.10s would do this if the gears had been properly identified and by their own admission, a person who works for an affiliated shop of the place I had the job done, said that they never rely on the tags but always pull the cover to confirm. When this "check" should of been done is a question that can be argued on both sides. I am not expecting to come out of this scott free but feel that an equitable compromise should and can be reached.

Anyone in the market for a set of: '93 3.08's, never turned 4.10 RP(dana 44) and TrueTrac(3.93or up), slighty used 4.10 RP(8.8)??

 

With your present setup you're running about 2150 RPM in 4th at 70. What's wrong with that? The 3.08s simply aren't enough gear for a truck anyway. You're now the equivalent of a 3.55 which is a good overall ratio. You've got better drivability, more performance, little or no loss of fuel economy and durability equal to a factory 3.55. Where's the downside? Count this one as a happy mistake and be glad it happened, you've got a better truck out of the process

 

I agree! I wish I could afford 4.10's Keep em.

 

whaynes,
I reran the numbers based on your M5OD tranny. Your 5th is only a 0.8 OD vs. the 0.7 for automatics which is what I had used.

Assuming about 635 revs/mile for your tires (please correct me if you have a more precise number, this is an educated guess based on 695 for 30" tires), you're turning about 2450 at 70 vs. 2200 if you had the 3.73s. It may be a little higher than you'd prefer, that's not an excessive number for a V-8, though it may be just a skosh high for an I6. In any case there's no significant amount of premature wear involved.

You've got a serious improvement in performance and drivability and in 4x4 capability and it won't hurt your around town mileage a bit. If highway mileage is a real problem, slow down a bit. Don't worry about excess wear and tear on the engine, it'll probably outlive us all

 

 

If you were in Montana You could swap axles with me any day. We have a 93 with 3.55's that we are going to put 4.10's in. If you take out your setup let me Know.