Tips for '06 Rubicon axles into a '01 TJ

[TJeeper]

I'm looking at getting a Rubi proportinal valve. I feel pretty confident that it will solve the issue.

It won't. I have one, it is the same as the one that came on my '99. The only way to reduce the pressure to the rear line is to install an adjustable proportioning valve like I said above. Stu has some pictures on his site how he did his.

[JpPassenger]

Did the fronts lock up first?

Patrick

I finally remembered to confirm it with my wife -- the rear locked up first.

I'm looking at getting a Rubi proportinal valve. I feel pretty confident that it will solve the issue.

We have definately opened the door for more damage to occur. The jeep would simply get hung up on the toughest obstaces (our members long ago quit telling her our jeep can't do "that" obstacle.) It was a good limit, I just had to replace tires for the first 4 years. Now, nothing stops her. In the brief time since the transformation: near rolls=4 (including a flop onto the side that righted itself.) mangled tailgate=1. creased rear corners=3. shredded softtop=1.

Some people set up college funds for their kids. We set up a maintenance fund for the Jeep.

[TJeeper]

The proportioning valve (in its OE configuration--in your case disk front/drum rear) will not allow the brakes to function properly unless you get extreamly lucky and end up with the same fluid requirements as the OE configuration.

Really? So you have experience with rear disc converisons?

FWIW I purchased a combo valve from an '03 Rubi, it was exactly the same as the combo valve that I have in my '99. They did have different part numbers, which is why I bought it. I have yet to see any evidence different combo valves were used in the various TJ models.

When I did my rear disc conversion with ZJ rear brakes, the original combo valve worked fine on my Jeep. I could only lock up the rear brakes at the end of a very hard stop- pedal to the floor. I could never lock up the fronts, so I upgraded to hydroboost, which is when the adjustable proportioning valve went into my Jeep.

[TJeeper]

It seems to me that the discs in the rear are more powerfull than the drums were, so it's easier to lock them up now. My wife locked them up coming down a fast wash a couple weeks ago.

Did the fronts lock up first?

The modification for the combo valve increases the pressure to the rear brakes, you don't want that.

If the rears are consistantly locking up before the fronts, you will need to plumb in an adustable proportioning valve. This is what I have in mine:

Wilwood proportioning valve

Patrick

[goodtimes]

I was looking for a dana 44 for the rear until I found the rubi 44's.

Just keep in mind that the rubicon 44's still have the thin(er) dana 30 tubes. They will bend easier than a traditional dana 44. That is not to suggest that they are *weak*, but if you do any stupid human tricks (jumping off of sand dunes, etc....) they do bend ...

[scherf68]

Say no more... Haha! I'm going to swap my rear to a D44 next year w/ ARB 4.88's maybe?, hopefully for around $2K. I doubt I'll do anything to the front (other than re-gear, and MAYBE lock it) until something breaks.

Keep your eye out on the forums, that is where I got mine Monday. I was looking for a dana 44 for the rear until I found the rubi 44's, I paid 2 grand for both axles and pumps. Drove it out of my garage today, no problems to report, just had to shorten the front driveshaft by 2 inches.

[goodtimes]

I believe the area of the disc piston is greater than the area of the slave cylinder pistons on the previous drum brakes. So the same psi will create more force across the larger area (and the brake pedal does requires more travel, corresponding to more fluid volume needed to move the piston.) I'm not certain how a proportioning valve helps after the initial application.

The proportioning valve (in its OE configuration--in your case disk front/drum rear) will not allow the brakes to function properly unless you get extreamly lucky and end up with the same fluid requirements as the OE configuration. The best bet is to either get a proportioning valve from the doner vehicle, or an adjustable prop valve so you can set it yourself.

[Materdaddy]

I paid $4k

Say no more... Haha! I'm going to swap my rear to a D44 next year w/ ARB 4.88's maybe?, hopefully for around $2K. I doubt I'll do anything to the front (other than re-gear, and MAYBE lock it) until something breaks.

[JpPassenger]

Keep in mind that the rubicons do not have ABS (at least they didn't in '03). It is not too difficult to lock the tires up, although the front tires should lock up before the rear.

No ABS on the '06 Rubicon's, either. Since we had the 30" wheel package with the D44, we didn't have ABS on our '01 either. But it is something to consider with the swap.

It seems to me that the discs in the rear are more powerfull than the drums were, so it's easier to lock them up now. My wife locked them up coming down a fast wash a couple weeks ago.

I will be the first to admit I don't know the answer, and am happy to hear from those with more experience. I believe the area of the disc piston is greater than the area of the slave cylinder pistons on the previous drum brakes. So the same psi will create more force across the larger area (and the brake pedal does requires more travel, corresponding to more fluid volume needed to move the piston.) I'm not certain how a proportioning valve helps after the initial application.

[goodtimes]

A new propotioning valve may be in the cards, since we did have the rear brakes lock up on a recent run. Rick posted a mod above for the exisiting proportioning valve, but I will feel safer getting a proper one.

Keep in mind that the rubicons do not have ABS (at least they didn't in '03). It is not too difficult to lock the tires up, although the front tires should lock up before the rear.

[JpPassenger]

I paid $4k, but they were new (had about 100 miles) and they were complete -- wires and connectors, hoses, compressors and bracket, disks, calipers, knuckles, draglink/tierod, etc. It was truly a bolt-in swap.

I estimate that I may have paid about $500 more than parts and labor to re-gear and lock the original D30/D44 combo, and switch to rear disks. But I also have the old axles for spares to boot, and the jeep was down for only 1 day.

I'd suggest that you put out the word at shops that sell/install Currie/9in/pro-rock 60's. There are people rolling their new Rubi's in there for axle swaps and you may get lucky.

Mounting the pump bracket was a minor challenge. The only real difficulty was having to shorten the front driveshaft. Make sure you measure length at full droop and full extention, especially if you have a short arm lift kit.

A new propotioning valve may be in the cards, since we did have the rear brakes lock up on a recent run. Rick posted a mod above for the exisiting proportioning valve, but I will feel safer getting a proper one.

The wiring diagram shown above is plenty to figure out the wiring. If I had a scanner, I'd scan the schematic I drew up.

In short, the wires coming out of the axle housing are the sense for the lockers -- they close a switch inside when the locker is physically engaged. So I mounted a couple 12V LEDs in the dash for indicator lights, and ran 12V through going into the sense lead, and ran the ground wire to ground. When the locker engages, the LED lights up.

The compressor pump wires are 12V going in on the relay output wire, and ground coming out. The switches I put in the dash switch the 12V to each pump.

It's a pretty easy swap.

[Materdaddy]

Where are you guys finding these rubi axles? Somebody let me know when there's a pair of 44s around that aren't like $3k... (or is that what you guys are paying?) You're acting like they're common place... "oh, look what I just picked up..." :smile:

[scherf68]

I just picked some rubi axles as well, is there any place on the net for reference. Also did you have any problems at all besides the front driveshaft? I got the rear in but not all hooked up.

[JpPassenger]

Good stuff, Rick, thank you. We did our trail (Fearless' Folly) and some further exploring out in El Mirage this past weekend. The brakes seemed to work fine with the exisiting PV.

We got the new cables and installed them, although I think they are for an unlimited instead of a standard rubi. They are pretty long.

All I have to do is fab a mount for the locker's air compressors and route the stock loom. I created a schematic for the controls and have the parts as well. It's all pretty simple stuff, I just need the time.

A diamond would have been cheaper, but she loves her 4.10s, the lift and the 4:1 TerraLow.

[RangerRick]

JpPassenger, you can keep the original proportioning valve and remove the black "O" ring (under the end of the prop valve with the pipe plug) if you want to from it. Be careful as this plug is under spring tension. Otherwise Rubicon proportioning valves are available on ebay and elsewhere for about $45. I have not done anything with my prop valve as of yet and my brakes work just fine. No dragging of the rear calipers or heat buildup noticed. On your parking brake cables, just order new ones from the dealer (under $40 each brand spanking new) unless you can find them used elsewhere cheaper. Order them for a 2003 Rubicon and they will fit ZJ Grand rear disc brakes and 03-06 Rubicons. Use a box end wrench that just fits over the one way clips on the divider bracket for your cables up under the center of the tub. The box end wrench will collapse all the "fingers" on the cable end allowing you to pull it free easily. It's nice to be able to lock up 37's on the street in an emergency stop with no problems as necissary with 4 wheel discs.

Rick W6RE
145.380, 223.780 PL 100 in LA & OC