Rear axle moan fix.

D.Hearne, let us know how long the fix lasts...there have been other posters who have added the friction modifier only to find out a few thousand miles down the road that "groan" returned. Hopefully it will be a permanent fix for you...but there is no guarantee.

When I changed my gears I had my installer add one bottle(4 oz) of friction modifier. After a few weeks I started getting the low speed groan during turns. I talked to a service manager at Ford and he said to add an extra bottle. So I went back to the installer and had him change the gear oil and put two bottle of the friction modifier in. So far, no noise.

If the problem comes back before the warranty expires...Ford has a TSB on that. Ford has had a lot of problems with the carbon fiber clutches.

I just had Ford replace the clutch packs in my 06's rear end under TSB 06-19-02A about 2 weeks ago. So far, it works perfectly - no more noise.

I had that same problem develop on my 05, and the solution was a bottle of friction modifier as well. Some people told me the noise would come back, but that was over 5000 miles ago.

Plus I recently switched out to 4.10s and so now I have all new fluids in the diff..... still no noise as expected .

I think it is worth trying the friction modifier before dropping your car off for a few days at the dealer.

How many miles does this first start to be noticed with the factory installed gears? I'm approaching 10,000 miles on mine with absolutely no gear noise. I plan on swapping the 3.55s out for 4.10s here in the very near future.

My wife got soo sick of the damn wining, we have been back and forth between ford about six times. Finally just bit the bullet and had Ravi at Speed Freaks install an auburn differential unit and some 4.10 gears. 8,000 miles later and running great, definetly worth it.

I had the tsb fix performed on my car about 15,000 miles ago, and the moan just came back again. I'm going to add some friction modifier and see if that helps. If it comes back, I'm ditching this POS Ford TracLock and throwing in an Eaton or Auburn or something.

I don't know what all Ford has changed in these rearends, but they've really screwed the pooch. The OEM 8.8 used to be a badass piece, but now they moan & groan, you get it fixed, and the moan & groan comes back; and only about half the time can you set up a ring & pinion to not whine in these cars.

The Ford Traction-Lok differential is a very good unit IMHO. If you are drag racing a 600 hp beast or auto-crossing to the point you are burning out clutches in the differential, then you may want to go to a Detroit Locker or Auburn or Eaton or whatever. For normal driving and some spirited romps or perhaps the occasional 1/4 track race, the stock T-Lok is pretty damn good. A clutch rebuild is only $50 or $90 in parts ($90 for carbon fiber clutches, $50 for standard clutches) and requires at most about 30-60 minutes of your time.

I hope the moan doesn't come back in 15K miles after the TSB clutch pack change in mine. My 06 has been a great car except for the rear end moan and noisy front struts (which Ford is working on a TSB for). How does a manufacturer have a design flaw on components that have been around for ever and should be tried and true by now. If it were some new cutting edge new technology feature I could understand, but it's basic stuff. Ford did a great job on the car overall and I still love mine, but they sure goofed in a couple of easy areas.

metroplex said:

The Ford Traction-Lok differential is a very good unit IMHO. If you are drag racing a 600 hp beast or auto-crossing to the point you are burning out clutches in the differential, then you may want to go to a Detroit Locker or Auburn or Eaton or whatever. For normal driving and some spirited romps or perhaps the occasional 1/4 track race, the stock T-Lok is pretty damn good. A clutch rebuild is only $50 or $90 in parts ($90 for carbon fiber clutches, $50 for standard clutches) and requires at most about 30-60 minutes of your time.

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... USED TO BE a very good unit. not any more. If you have to rebuild it every 10,000-15,000 miles, it's junk.

Pro Mod said:

... USED TO BE a very good unit. not any more. If you have to rebuild it every 10,000-15,000 miles, it's junk.

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Why do you have to rebuild it every 15k miles? If you are hearing the groaning noise while doing low speed turns, just add some more friction modifier. Usually if your clutches are shot, they won't make any sound since you now have a standard open differential.

You need a rebuild when you only leave 1 black mark on the road during a burnout, and that usually happens at 15k if you drive like a total moron or have raced your Stang frequently at the track. For normal driving, the Traction-Lok differential is a very good unit with solid mechanical parts and the clutches are cheap to rebuild every 50k-100k+ miles. I would not recommend wasting money and time on an aftermarket differential unless you are dedicated to racing your Stang very frequently.

how do you do it?

How/where do you add the friction modifier? Do you need to drain the unit first? Mine is quiet at 23K, should I leave well enough alone?

Normally when I re-fill the case, I add enough gear oil that it spills out of the fill plug (located on the backside of the case on the driver side, which faces the transmission and engine - it has been located here for the past 20 years in case you are new to Fords / 8.8" rear ends). The factory service manual and owner's manual state to fill enough so that it is a certain height BELOW the bottom of the fill plug hole.

The easiest way to do this is to use a turkey baster + vacuum hose or sometype of suction device to remove 4 oz of gear oil in the case and add 2 oz of friction modifier at a time until you no longer hear the groaning during low speed turns. When I rebuilt the clutches in a 98 GT take-off LSD for my 00 Vic, I did not add FM (on purpose) and the groaning basically sounds like metal rubbing (GRNNG GRRNG GRNNG GRNNG GRNNG) repeatedly during a turn. I added 4 oz of FM with 2.5 qt of fresh gear oil.

If you do not hear the sound, don't add more friction modifier. Too much friction modifier reduces the torque biasing of the unit and can accelerate wear of the clutches. not enough friction modifier may increase the torque biasing, but only until the accelerated wearing of the clutches finishes its course. The moral of the story is to use the bare minimum of FM to get rid of the noise.

metroplex, apparently you've not caught on to the fact that I'm not the only one with problems with the 05+ 8.8.

Regarding the moaning...
People (including me) are getting the TSB "fix" performed, the moan comes back in about 10-15,000 miles.
People (including me) are also trying to "band aid" things by adding more friciton modifier... guess what... it works for about 10-15,000 miles. So you think it's perfectly acceptable to have to replace my rearend fluid every 10-15,000 miles? that's rediculous.

The TSB is not a permanent fix, and adding more friction modifier is not a permanent fix. There is a problem somewhere, and the pre-S197 8.8's were badass. I'm going to find an OEM 8.8 differential out of a wrecked 04 GT somewhere LOL.

tr7driver, if your rearend isn't making any noise, then you have nothing to worry about. This is a hit or miss problem... some people have it, some don't.

Pro Mod said:

metroplex, apparently you've not caught on to the fact that I'm not the only one with problems with the 05+ 8.8.

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WRONG. I know for a fact there are MANY people with S197 GTs that have this problem with groaning during low speed turns. Thus far, every one of them has permanently fixed the problem by adding 4 oz of XL-3 Friction Modifier to the gear oil in the differential case. You are the only person that claims the Traction-Lok differential is a poor design that requires rebuilding every 15k miles, when it has been used for almost 20 years in various cars, trucks, and vans without any problems.

People (including me) are also trying to "band aid" things by adding more friciton modifier... guess what... it works for about 10-15,000 miles. So you think it's perfectly acceptable to have to replace my rearend fluid every 10-15,000 miles? that's rediculous.

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Here's the problem. If you are hearing A WHINE while moving in a straight line, it is NOT because of friction modifier, clutch packs, or the Traction-Lok differential. If it whines, groans, or makes noises while making low speed turns (figure 8s in a parking lot), then you should look at the clutches. I have never heard about a "whine" sound coming from a T-lok diff that needs more friction modifier. Usually whining comes from a rotating part like bearings or the gears. The clutches and steel packs are rotating at the same speed as the carrier when the vehicle is traversing in a straight line (assumng you aren't trying to do a burnout on a wet road). The groaning sound is similar to metal rubbing on metal repeatedly when you make a turn.

Adding friction modifier isn't necessarily a band-aid fix. 4 oz of friction modifier is REQUIRED with a new gear oil fill in the rear-end if you have a limited slip differential. I am not sure what the dealerships are doing, or what clutch packs they are required to use.

Since no one here on Stangnet or The Mustang Source bothers to ask the dealership to HOLD the old parts and give them to the customer, no one has been able to answer my question: Does the factory use the carbon fiber clutches or are they using the standard clutches on the S-197 GT rear end?

M-4700-C carbon fiber clutch kit: http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=6942

The standard clutches are used in 86-02 Mustang GTs and Cobras, while the 03-04 Cobra and the 07 GT500 are using the carbon fiber clutches. RUMOR has it the 05-up S197 GTs are using the same carbon fiber clutches, which might explain the unusual behavior (excessive groaning) since they are supposed to offer significantly MORE torque biasing than before due to the difference in friction materials. If the 03-04 Cobras never had this problem, then we must look elsewhere on the S197 GT.