3.55 Ratio

[Dadinator]

My front axle is boogered up and I want to replace it.

 

How common is the 3.55:1 ratio for a front axle (MJ or XJ)?

 

How about in the newer ones with the one piece front axle?

 

Are the newer ones a direct swap?

[carnuck]

It's almost the only front ratio with 4.0L and automatic.

[Dadinator]

Cool.  That's what used to be in it.

5 sp now.

 

Guess it will be easy to find, then.

 

 

So, are the newer ones a direct swap?

 

Thanks.

[carnuck]

The brakes changed in '91 (at least the rears) but the axles still bolted the same in till the end of production AFAIK. ABS makes for fun and around '99 I think they went to low pinion like the TJ and ZJ. Too bad you aren't close to Seattle. I have one ready to go from a '90 XJ for $200 less the brakes.

[onlyinajeep726]

Yes, the newer ones are a direct swap.  Larger u-joints too.  Back in April, I put a one-piece 4.10 geared HP D30 from a '94 4-banger XJ into my '88 XJ.  It was a direct bolt-in swap.  Swapped in C8.25 from the same XJ into mine to replace the D35 I had.

 

Also, ones from ZJs and TJs work also, but they're low pinion I believe and are far less desirable.  The TJ ones also have some caster adjustment on the axle side.  Stick with an HP D30 from a later model XJ... (2000-01 XJs had low pinions also)

[Dadinator]

Which years had the HP D30?

[mvusse]

HP D30:

All years YJ (but they are leaf sprung and of no use to us)

All years MJ

1984-1999 XJ

 

2000-2001XJ is low pinion, as are all TJs and ZJs.

[Dadinator]

So the MJ already has HP D30??

Didn't know that.

So, just need to get a non cad XJ one up to 99, then.

[mvusse]

Yes.

[Rockfrog]

any limited XJ will be non-CAD as well ... they had the NP242's

[onlyinajeep726]

One thing some people do is get the CAD 30 and swap the one piece axle shafts from a newer HP D30.  The older CAD D30 housing is a little stronger because of the extra casting of metal around the CAD opening.  Probably not worth the work if you don't need the added strength, but just something I wanted to put out there.

[mvusse]

This is debatable. Where the non CAD axles have a single tube from the pumpkin to the passenger steering knuckle, the CAD axles have a tube from the pumpkin to the cast CAD housing, then another shorter one from the CAD housing to the steering knuckle, so two more joints. Some people say this is prone to bending, but never witnessed this myself.

 

On the other hand, the CAD axle does have a nice strong cast upper control arm brackets. After grenading 3 CAD front axles (all with a single shaft conversion) I never had a problem with the passenger upper control arm bracket. One of these housings (with reinforced lower control arm brackets) now lives under my Cherokee with new gears and bearings.

 

The one non disconnect housing that followed them, I ripped the sheetmetal upper control arm mount off the axle on its second trip off road. Mind you, that was with a locker and 35" tires. I have fixed that problem by moving up to a Dana 60 axle, all 1/4" steel aftermarket brackets (and 37" tires).

[Dadinator]

I am going with a non CAD one just to eliminate a stupid design.