Hi all,

After shopping around a bit I settled on 4 Wheel Parts in Santa Ana for my 3.55 to 4.10 gear swap. Everything seemed to go well but after a few miles I realized that there was a whine on the rear diff under throttle between ~60 to 70mph (speedo is off so I'm not sure about the actual speed). From what I am reading this is generally a setup issue (backlash?). Anyway, tomorrow they are taking the truck back to correct the problem, they even ordered a new set of ring and pinion gears and the associated hardware. Here's hoping for the best, I'll post the results.

:Walker

 

Let us know what you find. My has a whine also. My mechanic has been back in it 3 times.

 

driveline vibrations are most likely your problem, the new gears will bring out the harmonics but the driveline u-joints must cancel out each other for the noise to go away or quiet it down enough to handle. cancel them out by equal degrees on both ends

 

The mechanic at 4Wheel Parts said they tried to "adjust" the new gears to remove the whine but they had some wear already that made them suspect. They are now in the process of installing another set of 4.10s in the rear diff. I asked about the other components of the drivetrain possibly causing the whine and they said *this* problem was with the backlash setting of the ring and pinion. Maybe I will work my way up to the other problems once they solve this one.

The good news? Mike @ Performance products said they can reprogram my chip to correct the speedo which is really off since the swap.

I miss my truck.

 

OK. I don't know if anyone is following this saga but after putting in the second set of ring/pinion gears, it appears that the pinion bearing may be bad. They installed the second set of gears again, this time with a new rear pinion bearing and at this very miunte they are test driving the truck. Total time w/o truck=4 days so far. Hoping they found the problem this time. I would like to say that they have been very open about the problems (the mechanic said the bad bearing was probably a result of too much preload during the first install) and have not asked me to pay any additional $$ (I think the bearing is about $60). I'll follow-up when I know more.

:Walker

 

Cool deal I am following this pretty intently. I want to do the same thing you did. Swap out to 4.10 gears in a 9.75... How much did 4 Wheel Parts charge you? I have a 4WP south of me and I know they do ring and pinion but I thought their prices might be extremely jacked up; but it sure sounds like they are doing right by you so I may give them a chance...

 

Pretty frustrated at this point. 4Wheel Parts told me the truck was ready and I went down to pick it up. They tried to charge me for the pinion bearing which is Bullsh*t since they already said it was most likely their fault (see above). I talked them out of that $50 bonus and took the truck....

Same....exact.....problem. Too pissed to do anything today, I'm gonna calm down and deal with it on Monday.

In response to Nonsequitur, the price was $1430 (front/rear) out the door but don't ask me to reccommend them to anyone today...my advice would be to find a Gear Shop to do it right the first time.

More of this frustrating saga when I talk to them on Monday.

:Walker (ironic name these days, doing a lot of walking).

 

Walker,

I am sorry that it is working out like this for you, but I am glad that you are sharing your experience so that I do not "walk" into the same situation!

Good luck to you sir, I hope this works out for the best!

 

Walknet,

If you are close to Anaheim, Ca; You might want to call Jerry @ UNitrax. I have known Jerry for about 16 years. See if he can solve your noise problem. Charlie in Indpls. Says "hello".
Good luck, gearman

 

Went to 4 Wheel Parts on Saturday and spoke to the regional service manager. He, like me, was not happy that this repair was taking so long and ordered a full install kit (presumably the bearings and shims) as well as my *third* set of r/p 4.10's for the rear diff. Made an apointment for Wednesday. Hoping they get it right this time.

Gearmanx17: Gotta stick with 4WP at this point cause its warranty work but thanks for the info.

:Walker

PS. How about those Patriots?? Yeah, Baby!

 

I've been in a similar situation (as a technician) after installing a motive set in a 8.5" chevy rear. Changed all brg's & R/P to US gear--problem solved.

Defective R/P looked okay; however, the new US gear set up as easy as OEM. Original size shims & spacers were reinstalled (same size as the OEM originals that came out of the 8.5" diff.).

Keep us posted. I hope they get you problem solved promptly, proffessionaly and accurately!

 

Still waiting for my truck in the shop but I was informed of an interseting piece of information from a knowledgeble poster on another forum. It seems that Ford changed the pinion length in the middle of the '99 year and the part number for the Precision Gear intall kit changed from f87-410 to f87-410L (the "L" stands for "Long" since the new pinion is 1/2 inch longer). From what I understand the old part number (no "L") will work in the new setup but only with additional shimming. I called 4Wheel Parts and they confirmed this information and admitted that they used the non-"L" part the first two times they setup the r/p because they were unaware of the mid-year change.

I don't know if they are going to get it right this time or not but I thought this may help others having the same problem.

Thanks to "burfa" who posted this on f150world.com in response to my post.

:Walker

 

after reading that thread im glad im not going to 4wp's. they quoted me $1400 for a gear change and a auborn locker install. i went to Auto Styles in lake forest( he did my rcd lift and have had 0 problems with it) and he quoted me $1100 installed. judging by the lack of knowledge at 4wp's and lack of up to date info, i know where im going. by the way, you should have been somewhere in the area of $1100 bucks for both. mitch

 

For those of you who have stayed with this story, two weeks later and I am back on the road. There is a *small* whine between 55 and 65mph (you have to roll the windows up and turn the radio off to hear it) but I am going to live with it. 4WP gave me a 5 year "Gold" warrantee to make me feel better and from talking to a bunch of people (Randy's R/P, US Gear, Drivetrain Direct etc.) there may be something going on with the 9.75 and the 4.10 gear set. Multiple shops are reporting problems with noise even with their most experienced mechanics. The mechanic at 4WP said he had to adjust backlash slightly out of spec to get the right contact patern on the ring, we took it apart after 100 miles and it looked like everything was lined up correctly. Off to the desert.

 

Just had 4:10's put in mine and havent had a bit of problems!
JJ