I ran into a problem installing Motive Gears 4:56's into my 97 F-150 with the 9.75 rear axle. The area on the pinion that the crush collar sits is 7mm shorter than the original pinion (3:55). Thus when setting pinion pre-load the collar doesnt crush because it doesnt contact the smaller pinion bearing. US Gear states when you install 4:56 gears on a 99 or older 9.75 rear axle you must use a solid pinion spacer with a shim pack. Has anyone ran into this problem? I cannot for the life of me find this solid pinion spacer anywhere online. Can anyone help?

 

A quick google search and I found this:

http://reiderracing.com/soild_spacers.htm



I believe that is what your looking for.

 

yup, they have the solid spacer kit I was looking for.........but they also state the 4:56 gears will only fit the 2000 and newer 9.75 rear axle. Motive Gear does not state this. Has anyone installed 4:56 gears into a 99 or older F-150 with the 9.75 and If so did you encounter the same problem? Would a 7mm spacer under the factory crush collar be the fix to this problem?

 

Has anyone installed 4:56 gears in a 99 or older F-150 with the 9.75 rear axle?

 

well I got my answer...........Ford changed the housing half way in 1999. To install the newer gear design(2000+) you have to use a special pinion bearing kit. No gear manufacturer makes the 4:56 in the older design. If anyone runs into this contact Precision Gear.

http://www.precisiongear.com/ford934htm

 

I am considering replacing the ring and pinion on my 98 with the 9.75 axle. Did the kit from Precision solve your problem? If so, how much is this kit?

 

Ford makes a crush sleeve spacer for the older housings. It's about six bucks at the dealer. Use a master install kit for 99 and older housings with the spacer. Ford part number YL3Z-4662-CA. Much easier and cheaper than a solid pinion kit.

 

i have a 99' 4.6l f-150 xlt sport 4x2 which had originally 3:08 in the rearend changed them to 3:73 and boy what a big mistake... i really wish i had put 3:55 's in ... been in for bout a year and that lil 4.6l has good take off but nothing to dish out when i need to pass a car at 80 mph..but is also my fault .. should have done my homework... ford didnt put anything lower than 3:55 in 99 .. i didnt find that out till i went to get the speedo calibrated.... so come tax time when i get a refund.. or when i come into a lil extra cash ill be changing them out.... not sure who told me to do this but man i regret it.. i kick myself every time i get in to drive it ...

 

Going to 3.55 from 3.73 is not going to change your passing at 80+. 3.55 & 3.73 is not a big enough change, I doubt you will even notice a change. I'd think about custom tunes from Mike Troyer before I would go from 3.73 to 3.55

 

I got my Motive 4.10 gears installed. The Ford Pinion Spacer for the older 9.75 axle worked perfectly. The truck drives so much better. If anyone is considering doing this on a 97 or 98 model I can give you any information that I learned. With 265/70/17 tires I had to change the speedometer drive gear to a 7 tooth yellow gear and used my existing 19 tooth pink driven gear. Speedometer is dead on.