Rear end cover question

[Daryl]

I’m still fairly new to my ‘95 Cobra (got it 4/4/20) and I’ve done a good bit of mods, repairs, etc. car has 90k with stock rear end (as far as I know) so probably 3.08’s. I’m fine with the gearing for now but I’m a bit of a “preventative maintenance “ kind of guy so I’m wondering if changing out the rear gear oil(75w90) wouldn’t be a bad idea? And in my research, I’ve come across various rear diff covers. Do these SVE and Ford Motorsport covers really make a difference?

 

[evilcw311]

I’m still fairly new to my ‘95 Cobra (got it 4/4/20) and I’ve done a good bit of mods, repairs, etc. car has 90k with stock rear end (as far as I know) so probably 3.08’s. I’m fine with the gearing for now but I’m a bit of a “preventative maintenance “ kind of guy so I’m wondering if changing out the rear gear oil(75w90) wouldn’t be a bad idea? And in my research, I’ve come across various rear diff covers. Do these SVE and Ford Motorsport covers really make a difference?

Changing the fluid can be good for your rear end plus it gives you a chance to make sure the fluid isn’t showing signs of flakes in it. The aftermarket covers are nice because they’re generally going to have heat sinks and fill&drain plugs where the factory doesn’t.


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[Daryl]

Thx, Evil. Good to know. Weird how the factory cover you have to basically remove the bolts (except for the top center), pull it away and just let the gear oil gush out. I mean, it works, but they could just as easily put a cover with fill and drain plugs, right? Just sayin’...

 

[Daryl]

Another question:
When the cover is off, will I be able to tell what gears are in it? If so, how? The metal tab is stamped for 3.08’s, but never know what the 2 previous owners did.

 

[evilcw311]

Another question:
When the cover is off, will I be able to tell what gears are in it? If so, how? The metal tab is stamped for 3.08’s, but never know what the 2 previous owners did.

If the tag is still there then 99% guaranteed to still be stock. Nobody ever puts those back on.


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[Daryl]

Figured as much. But no counting teeth, or looking for stamp marks?

 

[joe65]

you can also do the jack the rear end up rotate the wheel/axle and count driveshaft rotations compared to the wheel rotations. Google it. Yes you can also count teeth, but its kind of a pita.

 

[evilcw311]

Yeah you gotta use chalk to make a mark and see what the driveshaft/tire rotation count is.


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[96blak54]

Drive off in 1st gear, get it to red line rpm. If you are over 70mph before switching to 2nd....most likely 3.08.

I remember sporting the 2.73 gear. When sprint driving i never got into 3rd gear

 

[RAU03MACH]

https://www.crawlpedia.com/gear_tooth_calculator.htm


Have you pulled the cover yet to change the gear oil or the cover
if not
once you have pulled original cover off to change the cover and oil
count the teeth on pinion and ring gear
go to the link at top and enter the info and your gear should pop up
takes the guess work out

 

[Werecow]

You can also find the rear gear if it's not been changed by the door tag. Check the axle code on the door tag here and if it's not been changed (the door or the rear gears) it'll tell you what gear you have.

https://www.corral.net/threads/door-tag-axle-codes.270035/

Please pardon for posting from another forum..

 

[96blak54]

^ all good info.

 

[Daryl]

Awesome, thx! I’m on it today

 

[joe65]

https://www.crawlpedia.com/gear_tooth_calculator.htm


Have you pulled the cover yet to change the gear oil or the cover
if not
once you have pulled original cover off to change the cover and oil
count the teeth on pinion and ring gear
go to the link at top and enter the info and your gear should pop up
takes the guess work out

Its pretty tough to see the Pinon gear behind the trac lock.

 

[Daryl]

Instead of pulling it off today, I’m going to wait till I replace the cover & gasket. Ordering today.

 

[RAU03MACH]

Its pretty tough to see the Pinon gear behind the trac lock.

I was barely abel to see the edge of the pinon gear
I use a paint marker on the first tooth then count from there
Your right it's hard to see

 

[Wade_GT]

Might as well do 75w140 if you plan on driving it hard. Also, none of the diff cover gaskets seem 100% reliable against leakage, so RTV instead is suggested. I have the Ford Racing cover which is a nice piece, but the gasket has a slight leak.

 

[RAU03MACH]

Use purple jelly by lock tite also known as gasket maker
No gasket needed

 

[PinkieT]

On Mopar gears, the ratio was stamped on the side of the ring gear. I guess not on Fords, eh?

 

[RAU03MACH]

On the ford racing set they do
I don't recall if I ever seen that on the original gears
But you could be right about that
It would be on the side of the ring gear