I’ve looked high and low to no avail. Hopefully someone here can help me. I’ve been putting this off for a year plus. I built the rear diff a few years back and changed the ratio from 3.55 to 3.73. While I had it apart, I thought it would be good to change the clutch pack since it had over 200k miles. I used ford 75-140 and ford friction modifier, Everything was fine for a while. I used the dorman clutch kit from Rockauto and used the same thickness shim it had originally, .080 thickness.

Fast forward a year or two, and I started noticing chatter from the lsd clutches. So, I tried changing the oil and friction modifier. I used lube guard additive and Valvoline “with friction modifier” synthetic oil this time, but it made no difference in the chatter. So I ordered a new clutch pack, but many other projects and necessary repairs to other vehicles got in the way.

Fast forward another year, and I started getting weird bearing noises from the left axle bearing. So, it was finally time to attack this rear end. I put new axle bearings and seals on both sides. Interesting that the replacement bearings are cage type now, rather than the original style where the roller bearings ride against each other. Anyway, I also put in the Dorman clutch pack I’ve been sitting on for just over a year. I used lube guard friction modifier, soaking the clutches overnight in that. Put the clutches in using a home made spreader made from a 5/8” bolt with nuts and washers like many others have used. It was easy to get the 3 year old clutches out, but the brand new ones were very tight to get the spider gears to walk back in. Even though I chose to use the .070 shims this time based on what some others have said about using thinner shims to get rid of the chatter. I collected what was left of the 2 bottles of friction modifier from my clean soaking container back into the bottles and put it in the diff first. Followed by the Valvoline synthetic 75w-140 oil “with modifier” already in it. As soon as I backed it out of my shop, something seemed off. And then I turned the wheel hard out on the dirt, and the rear was groaning like crazy! WTF?! I drove over to the house vet slowly, still on dirt, and every turn was just plain awful!! I pulled it back in the shop and buried my head in the sand for a while.

Now, I’ve been back online and noticed what appears to be a change in the design of the clutch packs both from ford and Dorman. They are tan or orange in color, rather than dark grey/black, and have noticeable grooves in the friction material. Am I imagining this, or has there been an update??!! Is this an update to get rid of the blasted chatter? Obviously, the oil and friction modifier can get in between the plates MUCH easier with the grooves on the clutch discs.

Am I overthinking this and just need to give these new clutches time to break in? Or is this indeed a problem? Is the ford modifier really that different? The lube guard says it’s good for “all lsd units”.

I ordered a new Dorman clutch pack from O’Reilly today and will have it in my hands tomorrow to see if it really is different. It’s the exact same part number as before. I do believe ford has altered their part number by the last character to indicate an update or change in the part.

Please, any help would be much appreciated!

 

The new Dorman clutch pack came in and looked exactly the same! Solid black friction material. So, I ordered it again hoping to get a new stock part from a distribution warehouse. This one just got moved from another hub store nearby. Still holding out hope for someone to offer me some insight here. It's driving me crazy not knowing what to do here.

 

In case anyone is wondering, I ended up getting a clutch pack from Ford that came with pre-sized shims. No guessing, and no special tools needed. And used the ford additive with my favorite Valvoline gear oil. All is well again.

Now, for the bearing noise I was hearing. These sounds can really fool you! It turned to be a front wheel bearing. But now I at least have new bearings on all four corners once again!