97 Cobra Differential problem

[ghadab]

I have problem in my differential where when i am driving i hear a scratching noise and it is not putting the power down to both wheels (which drives me crazy). now i am planning to rebuild my differential and i really want your help guys.:

1- What type of differential came on my car (97 cobra)? is it LSD ? if not how does it differ from LSD?


2- i am planning to use my car for Autocross, track days and offcourse some street playing .... so what do you suggest me to do to me diff. to make it more active ?

3- our diff comes 28 spline, what does SPLINE means ? and how upgrading to 31 spline helps?

thank you in advance

 

[PACIFICGREENSVT]

28 Is the count of teeth on the ends of the axles.
You dont need to upgrade to 31 splines unless your going to make 400hp or more or drag race alot.
If your going to go racing you should rebuild the diff carrier it sounds like your cluthces are worn out, or just get a new one.

 

[Mark185]

It is an LSD, here is a great rebuild walkthrough... Trac-Lok rebuild how to.

I did this to mine about a year ago. Cheap and easy to fix

 

[no2moro]

If you are road racing, I suggest changing over to IRS.

 

[ghadab]

thank you guys for your replies

i can't change to IRS since it is very rear to find hear in dubai

guys what do you think of these diff:

Ford Racing 8.8 in 31 Spline Traction - LOK Limited Slip Differential w/ Carbon Discs at AmericanMuscle.com - Free Shipping!

or

Ford Racing 8.8" 31 Spline Traction - LOK Limited Slip Differential at AmericanMuscle.com - Free Shipping!

 

[Mark185]

the carbon discs are supposed to last longer than the standard ones. That's personal preference, I just used the standard discs. With those units you will have to get 31 spline axles too.

 

[ghadab]

thank you guys for your replies

i can't change to IRS since it is very rear to find hear in dubai

guys what do you think of these diff:

Ford Racing 8.8 in 31 Spline Traction - LOK Limited Slip Differential w/ Carbon Discs at AmericanMuscle.com - Free Shipping!

or

Ford Racing 8.8" 31 Spline Traction - LOK Limited Slip Differential at AmericanMuscle.com - Free Shipping!

if i will install one of the above differentials, would i still need this:

Ford Racing 8.8" Traction-LOK Rebuild Kit w/ Carbon Discs at AmericanMuscle.com - Free Shipping!

thanks

 

[Mark185]

if i will install one of the above differentials, would i still need this:

Ford Racing 8.8" Traction-LOK Rebuild Kit w/ Carbon Discs at AmericanMuscle.com - Free Shipping!

thanks

No because it comes with the unit.

 

[ghadab]

do you recomend ford racing lok LSD or other brand

 

[ghadab]

????

 

[ghadab]

guys which brand of these limited slip diff do you recommend me to buy

thanks

 

[ghadab]

any suggestions

 

[CJK440]

Do you realize that if you buy one of those 31 spline trak loks you will also have to buy 31 spline axle shafts too?

If you don't need the stronger axles, just buy a rebuild kit for your stock 28 spline trak lock. Its not hard to do.


When do you hear the scratching noise? If its a problem with the diff, it should only happen during turns. In a straight line there is no "differential action".

 

[ghadab]

No i will stay on the 28 spline.

regarding the scratching noise it is appearing on straight (the higher speed, the hire scratching noise) and also it appeare on turns

 

[CJK440]

No i will stay on the 28 spline.

regarding the scratching noise it is appearing on straight (the higher speed, the hire scratching noise) and also it appeare on turns

I think more diagnosis is necessary since differential problems tend to go away when going straight, if its a noise consistant with speed either straight or turning its likely something else.

Set the axle up on jackstands with the wheels a few inches off the ground. Put a jack under the centersection for insurance and run the car at different speeds to duplicate the noise. If its still there with the wheels in the air, its not the diff, keep looking.

You might also want to remove the wheels for safety and have somebody run the car at speed and see if you can identify it as you look under the car. Could be the brakes dragging, could be the driveshaft rubbing on the exhaust. Could be anything.

 

[ghadab]

i will try it and let you know

 

[Jimmysidecarr]

If it is the differential, and you plan on doing a bunch of open track and autocross, and you can afford it....

Keep your 28 spline stock axles and get a Detroit Tru Track torque sensing gear type slip limiter differential.
I love mine and even though I track a lot, no clutches in the LSD to wear out.
It is also much smoother than a clutch type diff.

Call these guys and ask them for a price on a 28 spline unit.
Differentials : Lethal Performance, Performance parts for Ford Mustangs

 

[ghadab]

thanks alot Jimmy ... and that is what i am planning to do. i do occasional autocross and i love and that is why i wanna fix mu diff

 

[Jimmysidecarr]

thanks alot Jimmy ... and that is what i am planning to do. i do occasional autocross and i love and that is why i wanna fix mu diff

A word of warning for suspension set up and driving technique:

You don't want to lift the inside rear totally off the ground, the dif will go open and you will have inside peel.
If you retain the OEM ABS the problem is minimal since the ABS will allow a little kiss of the brakes to refresh outer wheel traction with out having to lift.

Or you can just not set the car up to lift off.