Rear differential skid plate

[Celticlady]

Looking for a rear differential KJ skid plate.
I searched here. I didn't find anything. Nothing on the net for Liberty rear diff.

It has this harmonic counter weight hanging off the left side. What does this specifically do?

If I make a plate (add weight) will this cause issues?

 

[Shankster]

I'd think that a skid plate for a Chrysler 8.25 (if that's what you've got) with the right bolt pattern would work. I removed that counter weight with no adverse effects (and a lot of others have done the same).

RRO makes this diff guard for the Liberty:

Chrysler 8.25 Diff Guard: Chrysler 8.25 Diff Guard

Our bolt-on Jeep diff guards are quick and easy to install. Like all Rocky Road products, our Jeep differential guards have a lifetime warranty.

rocky-road.com

I see other 8.25 guards out there too that look more robust but pricier.

I don't have one, and not sure if it's really necessary - seems like that style would only be of help as you're sliding off a rock or backing up onto one. Something that protects the front of the diff too would seem to be the best but I'd be reluctant to add something that reduced my diff clearance.

I'd be interested to hear if anyone has had diff damage from contact with rocks and what the nature of that damage was. The front of the diff seems super stout but I'd think the sheetmetal cover plate is what would see damage - maybe one of those cast diff covers is the answer in that case?

 

[pmspoon]

I think the idea is to protect the U joint at the diff. and the bottom of the diff cover from peeling up if you slide off a rock.

 

[u2slow]

Maybe you can modify or copy this....

D44A/D44HD Differential Skid

Check out the deal on D44A/D44HD Differential Skid at Iron Rock Off Road

www.ironrockoffroad.com

 

[Celticlady]

Maybe you can modify or copy this....

D44A/D44HD Differential Skid

Check out the deal on D44A/D44HD Differential Skid at Iron Rock Off Road

www.ironrockoffroad.com

Do you know if the dana 30 and the 44 have the same cover bolt pattern?

 

[u2slow]

Do you know if the dana 30 and the 44 have the same cover bolt pattern?

They do not.

Also, regular Dana 30 is a different pattern from our KJ Dana 30. And they rear axle is most likely the 8.25" Chrysler.

 

[Shankster]

And they rear axle is most likely the 8.25" Chrysler.

I believe some came with the Dana 35 in the rear (although mine does have the Chrysler 8.25)

 

[Celticlady]

I believe some came with the Dana 35 in the rear (although mine does have the Chrysler 8.25)

What is difference between 8.25 and the KJ dana 30

Looking for same cover bolt pattern

 

[Celticlady]

If the harmonic balance weight removal is not a issue, I am thinking creating a skid plat similar to this. It would pick up the bottom 5 bolts. Installed on top of oem cover. Then go forward with a bracket to pick up the now gone weight attach points. It would go forward enough to protect the U-joint.

 

[Shankster]

What is difference between 8.25 and the KJ dana 30

Looking for same cover bolt pattern

You mean what is the difference between the 8.25 and the Dana 35?

https://www.cherokeeforum.com/attachments/f67/384357d1501535309-dana-35-vs-8-25-smile-1.gif

You can safely remove the counter weight and use those mounting holes

 

[Celticlady]

Thanks for the link
Ok a bit confused

A KJ dana 30 is not the same a other 30s?
Is a 8.25 the same as the kj dana 30?
Whats a Dana 35

These may seem easy questions for some.

There is so much info out there on differentials with most posters assuming you know wth they are talking about.

You mean what is the difference between the 8.25 and the Dana 35?

https://www.cherokeeforum.com/attachments/f67/384357d1501535309-dana-35-vs-8-25-smile-1.gif

You can safely remove the counter weight and use those mounting holes

 

[Shankster]

Thanks for the link
Ok a bit confused

A KJ dana 30 is not the same a other 30s?
Is a 8.25 the same as the kj dana 30?
Whats a Dana 35

These may seem easy questions for some.

There is so much info out there on differentials with most posters assuming you know wth they are talking about.

Your KJ Liberty has a Dana 30a in the front - most Dana 30 that came in other vehicles are different because they have a solid front axle. The Liberty does not have a solid front axle because it has independent front suspension. One of the other big differences between the 30a and the regular 30 is that the 30a has an aluminum housing, the regular 30 has a cast iron housing, the 30a is therefore weaker than the already weak 30. Probably no need talking more about the Dana 30a here anyway because it doesn't need a skid plate of its own because it's already well protected by the front skid on your Liberty. There may however be a benefit to installing a heavy duty cast iron (or aluminum) diff cover on your 30a because it will strengthen the housing and reduce the likelihood of it cracking due to internal forces or twisting of the housing that might happen when rock crawling etc.

The KJ came with one of two rear axles / diffs. Some came with a Chrysler 8.25 and some came with a Dana 35 - if you don't know what yours has that would be the first thing to figure out. They are completely different - different housing, different cover, different internals, different bolt pattern. That link I provided shows photos of both - easiest way to identify what you have is that the Chrysler 8.25 has a flat bottom on the flange of the housing, the Dana 35 is more rounded. The Chrysler 8.25 is considered the better diff because it is bigger and heavier duty. If you Google "Chrysler 8.25 vs Dana 35" you'll find a bunch of videos comparing the 2.

 

[u2slow]

Thanks for the link
Ok a bit confused

A KJ dana 30 is not the same a other 30s?

There's a number of variations of Dana 30. High vs low pinion; fat vs short vs 'regular' pinions. The most standard traits are the ring gear size and 27 spline carrier.

The's KJ's IFS-variant diff cover has slightly different bolt holes, and is shallower - due to the packaging of this aluminum version in the chassis.

Imho, if there is a weak portion of this diff, it's the aluminum tube extending off to the passenger side. It looks as though a direct blow or hard twisting could snap it. I dont think a beefy diff cover will help that.

Edit: the Dana 35 has been a common jeep rear diff since at least the 80's. Generally regarded as weak. It may have been the drum-brake or 4cyl KJ diff in early models. The 8.25" was commonly used with V8 power on other Chrysler products.

 

[Shankster]

Edit: the Dana 35 has been a common jeep rear diff since at least the 80's. Generally regarded as weak. It may have been the drum-brake or 4cyl KJ diff in early models. The 8.25" was commonly used with V8 power on other Chrysler products.

I have an early drum brake model - it has the Chrysler 8.25. Also, since the 4cyl KJ is the go-to donor for 4:10 gears for the Chrysler 8.25 I don't think there is necessarily any reason to think 4cyl KJs got Dana 35s more than 6cyl KJs did.

 

[u2slow]

I have an early drum brake model - it has the Chrysler 8.25. Also, since the 4cyl KJ is the go-to donor for 4:10 gears for the Chrysler 8.25 I don't think there is necessarily any reason to think 4cyl KJs got Dana 35s more than 6cyl KJs did.

Did some more checking.
The D35 doesn't list for 2003-onward.

You must be registered for see images attach

 

[Celticlady]

Your KJ Liberty has a Dana 30a in the front - most Dana 30 that came in other vehicles are different because they have a solid front axle. The Liberty does not have a solid front axle because it has independent front suspension. One of the other big differences between the 30a and the regular 30 is that the 30a has an aluminum housing, the regular 30 has a cast iron housing, the 30a is therefore weaker than the already weak 30. Probably no need talking more about the Dana 30a here anyway because it doesn't need a skid plate of its own because it's already well protected by the front skid on your Liberty. There may however be a benefit to installing a heavy duty cast iron (or aluminum) diff cover on your 30a because it will strengthen the housing and reduce the likelihood of it cracking due to internal forces or twisting of the housing that might happen when rock crawling etc.

The KJ came with one of two rear axles / diffs. Some came with a Chrysler 8.25 and some came with a Dana 35 - if you don't know what yours has that would be the first thing to figure out. They are completely different - different housing, different cover, different internals, different bolt pattern. That link I provided shows photos of both - easiest way to identify what you have is that the Chrysler 8.25 has a flat bottom on the flange of the housing, the Dana 35 is more rounded. The Chrysler 8.25 is considered the better diff because it is bigger and heavier duty. If you Google "Chrysler 8.25 vs Dana 35" you'll find a bunch of videos comparing the 2.

To clarify my original question was only concerning the rear diff.

Yes, your link was very helpful. I have a 35.

So back to original question obtaining an aftermarket REAR differential skid plate.

If none are available, then constructing my own from the picture above as the basic plan.

 

[Shankster]

So back to original question obtaining an aftermarket REAR differential skid plate.

If none are available, then constructing my own from the picture above as the basic plan.

I googled Dana 35 Skid Plate and it seems really strange that nothing (other than a cover guard) shows up. Let us know what you come up with. I can see how the u-joint and rear of the driveshaft could get damaged on a big rock but that also seems like a very low probability situation. The risk:reward ratio isn't high enough for me to pursue something like that - compromising clearance on what's already a low point under the vehicle is not worth the small benefit a skid plate would provide for me - just my opinion and I hope I don't have to eat my words some day.

I just installed a Yukon cast iron diff cover on my 8.25 - I figured it would strengthen the already stout diff housing, and would not peel off or puncture like the factory cover could if I ever drop onto a sharp rock. It also provides a flatter, distortion free flange surface that should reliably seal with a gasket (instead of silicone sealant). Another thing I liked when I bought it was it has a drain plug - unfortunately it appears to be positioned too high to allow all of the gear lube to drain out. Another complaint is that the fasteners and drain/fill plugs have SAE hex heads instead of metric - so I have a Jeep I service with a set of metric tools with these non metric fasteners?? The ARB diff cover looks like a better design but I decided to save $75 by going with the Yukon - I'd probably splurge on the ARB if I were to do it over.

 

[seafish]

The ARB diff cover looks like a better design but I decided to save $75 by going with the Yukon - I'd probably splurge on the ARB if I were to do it over.

Yup the ARB 8.25 rear diff cover made from nodular iron is almost its own skid plate —

What did you do to your jeep today?

The part arrived 2 or 3 days ago, early. Is that the BWD from rockauto ?? I'd be curious to see a side by side pic of the toasted Four Seasons and the BWD…I never got to comapre them directly.

www.jeepkj.com

 

[u2slow]

I googled Dana 35 Skid Plate and it seems really strange that nothing (other than a cover guard) shows up.

Not so strange. That D44A created a market for one because it's aluminum.

Iron diffs take lots of abuse. Folks grind them to be smoother to hang up on rocks less. (Some diffs are cast more favourably for improvement vs others).

 

[Shankster]

Not so strange. That D44A created a market for one because it's aluminum.

Iron diffs take lots of abuse. Folks grind them to be smoother to hang up on rocks less. (Some diffs are cast more favourably for improvement vs others).

Ah, gotcha re the D44A. I appreciate that my Miata and Fiat Spider are mostly aluminum (sub 2500lbs is where I want my sports cars) but I'll take cast iron and steel on my Jeep wherever possible. I guess if I ever get hung up on my 8.25 I'll look for some way to get it to slide over stuff better.

I did find a discontinued skid plate for a Dana 35 here:

Rock-It Parts Rock-It Differential Glider for Dana 35c Rear Axle

Anyone who has spent any time on the trail knows that a differential will take a pounding. From mild to extreme trails, it's easy to have you front and rear diffs caught on an obstacle. The logical solution is a Rock-It TM Differential Glider.

www.quadratec.com

That might be an option to copy Celticlady - wouldn't be too hard to fabricate. I agree that mounting to the counterweight mounting holes would be the perfect place though.