? about vac disco

[DansGreyMj]

i went to the yard today and all they had was a non disco 30 with 3.54/3.55s from a 90 my question is what do u guys do with the vac lines when u get rid of the disconnect, and the guy kept say that i would have to swap out the knuckles and the brakes but he never told me why anybody have any idea wth he could have been talking about, also would it make any difference if i had 3.55s on one end and 3.54s on the other?

[JeepcoMJ]

the 3.55 vs 3.54 gear isn't a problem

 

when you put in a disco front end, you remove the vac. lines entirely...all the way back to the tranny. then you remove the tranny sending unit and replace it with a brass fitting that threads in, or you plug all the vac. holes on it. make sure you plug anything you disconnect the lines from, or run new lines just to the vac. cannister.

 

it's easy

[Eagle]

and the guy kept say that i would have to swap out the knuckles and the brakes but he never told me why anybody have any idea wth he could have been talking about, also would it make any difference if i had 3.55s on one end and 3.54s on the other?

3.55 and 3.54 is normal. The two axles have different diameter ring gears and pinions. The tooth count can't be the same. The gear ratio is the number of teeth on the ring gear divided by the number of teeth on the pinion.

 

Here's why the guy at the yard mentioned knuckles:

Steering knuckles: There are two designs of steering knuckle, and within each design the left and right sides are mirror image and carry different part numbers. The early knuckles were used from 1984 through 1989. The late knuckles were used from 1990 through 2001.

 

Hub/Bearing: Three different hub/bearing assemblies were used. The hub/bearing assembly is the same for both sides of the vehicle. The first type was used from 1984 through 1989, and must be mated to the early steering knuckle from the same range of years. The early hub/rotors used tapered roller bearings, which are available as individual replacement parts, and in theory can be rebuilt. In practice, removing the old bearings and installing new ones requires a large arbor press and bearing splitter, equipment not available to the average owner. In practice, even dealerships simply replace the entire assembly, because the labor cost to rebuild would exceed the cost of a replacement assembly.

 

The second type of hub/bearing assembly was used from 1990 through mid-1999. This hub/bearing assembly mates up with the newer style steering knuckle and is used with composite rotors. Certain years of XJ with composite rotors were subject to a safety recall if they were located in northern “rust belt” states, because of problems with the rotors (see below). When replacing hub/bearings in vehicles within this range of years, unless the vehicle recall history is known it is wise to call a dealer or DaimlerChrysler customer service to determine whether or not the vehicle has undergone the brake rotor recall. If so, confirm which hub/bearing assemblies should be used as service replacements..

 

The third type of hub/bearing assembly was used from mid-1999 through 2001. This hub/bearing is also used with the new style steering knuckles, and is mated with the newer style cast rotors.

 

Rotors: Three types of rotors were used. Rotors are the same for left and right sides. The first style of rotor was used from 1984 through 1989. The second style of rotor was used from 1990 through mid-1999. This second style rotor was a “composite” design—the braking surface disc was separate from the center “hat” section, which was stamped from comparatively thin sheet steel. After several years of service, it was found that in states and localities where salt is used on the roads in winter, corrosion of the “hat” section could result in the disc portion separating from the assembly, causing a loss of brakes. A factory recall was issued to correct this problem. The recall affects only vehicles within a range of years, and only in certain states. Anyone owning a Cherokee or Comanche in the range from 1990 through 1999 is advised to call a dealer or DaimlerChrysler customer service with the VIN number to determine if the vehicle is subject to this recall.

 

Mid-year in the 1999 model year the front brakes were changed to an all cast rotor design. Although the original, early style rotors were also all cast, the new rotors are different from the early ones and carry a different part number. The new cast rotors were used from mid-1999 through 2001. Because 1999 was a transition year, owners of 1999 Cherokees will need the VIN number to determine the correct parts to order when servicing the front brakes or hub/bearing assemblies.

 

Calipers: Two styles of caliper were used. The calipers are mirror image for the left and right sides and carry different part numbers within each group of years. The early style caliper was used from 1984 through 1989. The later style caliper was used from 1990 through 2001 and is used with both the composite rotors and the newer cast rotors.

 

As previously noted, a complete front axle assembly from any year Cherokee or Comanche can be installed in a Cherokee or Comanche of any other year. It is only when attempting to swap components among different years that the above parts differences become critical.

[DansGreyMj]

hey eagle thanks for all that info, if i were to swap in the entire assembly(brakes hubs rotors knuckles, etc.)would it work fine in my 87?

[Eagle]

Dan -

 

Yes, of course it will work. See the last paragraph of my quote above.

 

The Catch-22 is that you must forever remember that you have a 1990 front axle and order anything for the front (rotors, hubs, calipers, brake pads( for the '90. The hub offsets are incrementally different and if you mix '87 calipers and/or rotors on the '90 hub ... they won't rotate. As long as you remember to order the correct parts for the axle, it's just fine. Print out a copy of that listing I posted, it'll help you keep track of what you can and can't interchange.

 

One other factor to remember is that the 90+ rotors are the crappy composite style rotors that warp if you speak harshly to them. If it were my choice, I would try to hold out for an '89 or earlier front axle, or else swap over the parts to enable me to keep using the '87 brakes. I've been a member of the "rotor of the month" club and I didn't enjoy it.

[86FUBAR]

I'm about 99% sure u can swap the whole knuckle assy. from any year dana 30, thats my plan any way on my rubi 44 since its still got 30 inners but if u know any better speak up.

[Rokhound]

After reading eagle post a couple of time the only way to run 87 brakes on my 91 axle is to change knuckle right?

 

If that is the case how hard is it to take the knuckle and swap it out is it worth the effort.

[86FUBAR]

remove the cotter pins in the upper / lower ball joints then smack the knuckel with a hammer ,pops right off then install in reverse, of course don't for get about the axel .

check the manual fer torque specs and such and thats it .

[DansGreyMj]

so if i swap th knuckles i would use my hubs from my 87 also on a scale of 1-10 how hard is it to swap knuckles? ive never tried it but it seems like it would be pretty simple

[86FUBAR]

1-10 A SAY A 4

[mjeff87]

remove the cotter pins in the upper / lower ball joints then smack the knuckel with a hammer ,pops right off then install in reverse, of course don't for get about the axel .

check the manual fer torque specs and such and thats it .

 

You do sidework writing for Haynes/Chilton's? :rotf:

 

Jeff

[Rokhound]

I just plugged my t-case today 5/8 FINE thread plug worked great.