Rear end ckunking on left turn
 

I have a '57 Sunliner and rebuilt the 9" differential about two years ago using a good used ring and pinion along with all new bearings and clutch plates and have only put less than 200 miles on it. It has now developed a clunking when turning left. I have read that this can possibly be caused by a faulty axle bearing or needing friction modifier. I used specific LSD oil when I assembled and filled the Diff. I would be interested to hear the thoughts from those more experienced than myself to help solve this problem. Thanks in advance :)

Re: Rear end ckunking on left turn
 

The rear has a clutch kit in it?

XL-3 Friction Modifier Additive - 4 oz.

https://www.amazon.com/Ford-XL-3-Fri.../dp/B000NU5LP6

What LSD LUBRICANT did you use for reference?

Re: Rear end ckunking on left turn
 

Yes new clutch kit when I rebuilt - I will need to check the container

Re: Rear end ckunking on left turn
 

This is the oil I used

Re: Rear end ckunking on left turn
 

I know different units require different additives, and my current ford experience is with an old Dana 44 in my bird. Probably different. But right after they outlawed whale oil I remember having problems with a posi unit. The answer was more additive, the new stuff wasn’t as good as the whale oil. It was just a couple ounces in that case.

You might check the specifics of what you used with the oem Ford (assuming it’s old ford parts) recommendations. If it’s aftermarket clutches, they may have a different spec.

Re: Rear end ckunking on left turn
 

I checked the NULON WEBSITE and the fluid does not meet FORD SPEC EST-M2C118-A.

https://www.motorcraft.com/us/en_us/...modifiers.html

https://www.nulon.com.au/products/ge...fferential-oil

IMO ... :rolleyes: ... add the FORD LUBRICANT, do a series of tight turns in a parking lot and see what happens. If no relief, the clutch pack break-away value can be checked on a lift with a break-away value torque wrench.

Where did you find the clutch unit? FORD did not use until the 1959 model year.

There is no one-fits-all lubricant and 20,000 mile oil changes, despite what the manufacturer tells you.

Re: Rear end ckunking on left turn
 

Thanks for all advice, I have ordered the Motorcraft friction modifier and will let you know how it works out. :)

Re: Rear end ckunking on left turn
 

It's the easiest, so good idea to give it a try. Honestly, the first thing I thought of just reading the title was the lube.

Re: Rear end ckunking on left turn
 

Me too!

Re: Rear end ckunking on left turn
 

[QUOTE=KULTULZ;2303201]

Where did you find the clutch unit? FORD did not use until the 1959 model year.

After getting my '57 home to NZ, I found that it had had a '59 292 Y-block and 2-speed auto installed, (with the engine mounts reversed) so nothing lined up with for the Transmission mount or drive shaft. Luckily I found a correct 3-speed auto, complete with drive shaft and all necessary parts from a '57 to swap into the Sunliner. I can only assume that the rear axle might have been changed at the same time by a previous owner?

The friction modifier has arrived today so this weekend I might have time to put it in, however the weather is not going to be fine enough to test it out. Hopefully I can do that the following weekend, subject to the weather being dry that is. :)

Re: Rear end ckunking on left turn
 

Here's a couple of pic's of the Sunliner, as purchased and from last weekend.

Re: Rear end ckunking on left turn
 

Isn't that something? FORD began offering the clutch rear end in 1959 so that would explain it.

The SUNLINER is nice and is going to make a beautiful driver. I see it has a BIRD ACL. Nice touch. I have always wondered why guys did not use that ACL when dressing one out, especially with the BIRD ALUM ROCKER COVERS.

Hope the FRICTION MODIFIER works out for you ... ;)

BTW - Are MOTORCRAFT LUBRICANTS readily available down there? I have exchanged with several AU guys that say it is hard to find even at a dealer?

Re: Rear end ckunking on left turn
 

***** UPDATE *****
Thanks to all who responded, I sourced the Motorcraft fiction modifier, put it in the diff. went for a drive on Saturday, and voila, it would appear that my clunking diff. has been cured, thanks to all for your help, much appreciated. :)

Re: Rear end ckunking on left turn
 

Meric, good deal! They changed the friction modifier formula at some point but it still works good. If you got the original on your hands you couldn't get the smell out for weeks! Ford techs would ask parts guy for a bottle of "the stinky stuff".

Re: Rear end ckunking on left turn
 

It sure does stink :(

Re: Rear end ckunking on left turn
 

Oh and I'm sure it was changed for the better...yeah right!