'10gtpony

The bolt heads are 1/2". I believe the person asking the question was inquiring about the head size, not the thread pattern.

Also look here in the manual it says only 1.5L of axle lubricant and doesn't mention the friction modifier!
http://iihs.net/fsm/?dir=93&viewfile...ng%20Cover.pdf


I did this last night and my 8.8" differential took 2.5L of 75W-140 and 4 oz of the friction modifier.

1FastStang13

I just swapped out the factory 3.31 gears in my diff to 3.73 and filled the rear end with Royal Purple 75W 140 and the Friction additive that came with the 3.73Gear kit.

I have 2 questions, 1) Since the Royal Purple has the friction additive already, will it harm anything if I added the friction modifier that came with the gear kit? The gear kit I purchased from AmericanMuscle.com included t quarts of the royal Purple and the 4 oz bottle of friction modifier.

2) I have the 8.8 inch ring gear and read that it takes 3 quarts of gear oil. I went and purchased a 3rd bottle and filled the differential with the rear axle unsupported. I am noticing a strong gear oil smell overtime I get in the car and am wondering if I have overfilled the diff. I filled it until oil was coming out of the fill hole and did not think to jack the axle back up to normal ride height and let some oil drain. I am thinking that the excess oil may be coming out the axle breather and want to know if it is slight overfilled, it could cause damage?

Thanks for any feedback!

SCCAGT

axle supported or unsupported should not have any negligible effect on measured level. If anything, it would be lower because the axle drop is going through the 3-6 o'clock motion. And if the front was still down, then the angle of the car pretty much offsets it.
I really doubt there is enough friction modifier already in the bottle of RP. American Muscle probably would not have sent it as part of the kit if that were the case. I am certain you are not the first person to have purchased the kit from them. Therefore, they would have already heard about it. I used Amsoil Severe Gear which is also suppose to have the modifier in it as well. After driving, it was readily apparent it wasn't enough. So I had to add some modifier.

Gear oil has a stink that doesn't go away very easily. Go ahead and keep driving before jumping to conclusions. Filling until it comes out of the fill hole is the proper way to determine level.

So, how nice is the change to 3.73 for acceleration?

BrianK

For those wondering about using a suction pump to clean out the old oil, (as a Jippy Lube place will), my opinion is that you will probably not be cleaning out any sludge that may have accumulated in the bottom on the housing. I found there is quite a bit of oil left in these places even with taking the cover off and requires a few rags to get this all cleaned out. So my recommendation is to remove the pan and really clean out the old oil before adding new.
I used RP once and found that it was kind of dirty when I changed it recently. I did use a Ford friction modifier as well. This time I used Amsoil and a FM. Will see how it performs. No noises from the diff this time either.

doctorpimp

Good write-up - Thanks!!!

Invective

I paid my garage to change my diff fluid last year; $90 parts and labor for synthetic fluid and the special fluid you are supposed to add to it (friction modifier). I wanted to get a Ford Racing diff cover but was pretty broke by then as my '10 Year Anniversary Service' set me back $380 total. Car had around 18k miles at the time. Money well spent IMO. Cleaned the K&N filter for the first time too.

BrianK

I regularly read comments about (and see the OP pictures) Pumpkin Jacking with the tone that it can damage your diff or axle. Because of this I generally jack from each axle end by the wheel but occasionally it would be so much more convenient to just jack the rear end from the diff. Has anyone had any problems when pumpkin jacking or is this a misconception?

ghunt

I've always raised my vehicles by the pumpkin and I don't know what's so bad about it. I think problems arise when you get the jack back too far where it's under the edge of the diff cover and bending it, which can cause leaks.

jz

Same here. Been jacking by the pumpkin for 20+ years and never once had an issue.

BrianK

Thanks guys. I used to PJ too but after reading the comments suggesting it was wrong I stopped doing it. I won't feel so bad PJ's anymore.

I can understand that if you PJ, there is a lot of weight being put on the contact point on the diff, and the axles are truly designed to supposed to handle that weight close to the shock support but it is so much easier to jack from the diff and put jack stands under the axles.