Need help clutch or rear diff.
 

I’m having an issue and I don’t know what it is. When I do a mild launch on my car the tires start to spin then is they stop and seems like it’s slipping. Can figure out if it’s the clutch or too much friction modifier in the rear. When I replaced the rear differential fluid I used the royal purple limited slip oil plus almost a whole 4 oz bottle of Ford friction modifier because I didn’t notice the royal purple had it in it already. Car has 58k miles on it. What are your thought? Thank you

Re: Need help clutch or rear diff.
 

If you go to the LMR website where they have the royal purple for sale there is a note toward the bottom that basically says although their gear oil has some FM in it you still need to add the ford FM. They actually include it in the package.

Slipping after you get traction? So the tires spin and then you get traction. From there what happens? Is the engine revving more freely? Car stops moving forward? What does it do under normal driving/launch?

Little more detail if you can. Would like to help.

Re: Need help clutch or rear diff.
 

I will take it out again tomorrow and pay closer attention to it but I feels like the the tires spin and the car starts going sideways then falls on it’s face. I do have 4:10 rear gears and even have a hard time breaking the tires loose when I mash on the gas in second or try chirping them. Also have the occasional issue going into reverse where I have to go into first then reverse or it will grind. Traction control is off when I tried the mild launches. They are new Bridgestone potenzas so maybe they are catching traction and I’m not on the gas enough and that may also be why I can chirp gears. May have to put my stock wheels on to see how it drives

Re: Need help clutch or rear diff.
 

Having run the Potenzas I will note that they grab pretty good once warm. That said, with 4:10 gears you should be able to over power them. If the rpms are increasing but the car isn't pulling at the same rate (assuming no wheel spin) I would be leaning towards the clutch. Would think slipping in the rear would just result in only one wheel spinning. If the car is bogging after the tires grab, it is neither the clutch nor the rear, would be looking towards the engine.

Re: Need help clutch or rear diff.
 

i was thinking the same thing...if something was slipping the engine would keep revving, not "fall on it's face" as described. in the OPs second post. sounds more like the tires are getting traction after breaking loose and the car bogs down....car just needs more power to prevent that.

Re: Need help clutch or rear diff.
 

This is a car I don’t drive very often so I’m thinking it’s all me. I can launch it in either first or second gear and get the tires to spin and the car doesn’t bog I must have been too light on the gas the other day and the tires must of caught traction.

Re: Need help clutch or rear diff.
 

i'm just going to toss this out there, did you push the traction button so it will spin them? Just a thought, it happens to the best of us.

ASh