D30 swap

In my 48cj2a I am changing my front differential from the D25 to a D30. Is there any pit falls to watch out for or tips on doing this easily? For simplicity I think I will keep the ross steering box and bell crank. What master cylinder is best to use for a disc/drum brake setup?
I did do a search but I keep getting a "fatal error".

 

I was planning on the same swap eventually, but wasnt gonna get all fancy with brakes and stuff.

 

When I did mine, I installed hanging pedals from a CJ 5 and changed my shock mounts to be somewhat behind the wheel and angled back. I made them out of 1" x 2" rectangular tubing welded to the frame and used a 7/16" grade 8 bolt as the top mount. I used the spring plates from the D30 which have two shock suds, one in front of the axle and one behind. That way I could use the back ones for the shock lower mounts and the fronts for the sway bar(which also came with the D30) cause I have Holbruck springs and they are excellent off road but a little scary at medium to high speed on the road. You'll also have to redo the brake lines. The D30 came with two lines, one for left and one for right. The 2A has only one feed. I made all new ones and made the single feed line attached to the frame on the drivers side bout 6" behind the front cross tube that supports the radiator. Used a flex line down to a tab I welded to the axle housing where I had the T from the D25 and then ran new lines out to near each backing plate, welded on two tabs (one for each side) for the transition to the flex lines to the wheel cylinders. Phew. I used a dual master cylinder from a CJ 5 to attach to the hanging pedals. I have been told that you can use the stock 2A master cylinder if you drill a couple of holes in the thin tin washer on the piston of the mas. cyl. so it will allow the pistons on the disks to return back so the pads don't drag. I also put an adjustable proportioning valve so I could adjust the bias (pressure differences) between the front and rear brakes so one or the other doesn't lock up. Sounds easy doesn't it.

 

Thank all of you very much for all the info.
NoFlyZone- My D30 came with disk brakes on it. I have been rebuilding my D25 and doing many upgrades but finally realized it was best for my intentions to just do the axle swap now.
As far as using CJ-5 hanging pedals, is there any particular years that work best? Is there any body tub reinforcement that need to be done?

 

Have you guys all kept the axle spring under or did you mount the axle spring over? Right now I plan on keeping the spring under, I think a spring over will give me way too much lift. I really don't want very much lift, maybe 2" max. eventually. Holbrook I assume is a spring mfg., is this a type of long leaf setup?

 

I Agree. They're like ridin in a Lazy Boy and they'll give you a 1 to 2" lift. My hanging pedals were from a late 60's CJ 5, I think. I just bolted them to the firewall with the stock CJ bolt holes and then there is part of the pedal assembly that comes back towards the dash and one bolt goes through there. That's plenty of support.

 

Thanks again for the info, I do have a set of early cj-5 pedals lying around. I will also look into the Holbrook springs.

 

After this last trip I am definitly doing some serious brake upgrades. My crappy brakes had me in some way dangerous situations.

 

If you are thinking of keeping drum brakes but wanting larger ones, I have a complete set of early Ford Bronco 11" self adjusting drum brakes for the D25/27 I am willing to sell.

 

Whose u-bolts to use for the spring mounts? What year, model, and where to order them from? I have conflicting info on what size etc. to use. I measured the spring plate holes and they are just under 9/16". I keep finding 7/16" u-bolts listed for an early cj-5. My cj5 spring plates both have 3" between the holes, the tube dia on the D30 is 2.5". The only u-bolt that is 3" is the one that goes over the diff housing.:?:?

 

I got the D30 installed enough to crawl around the parking lot in low. I used the CJ drag link and connected it to the Ross steering bell crank. I can turn right really nice but not much left turn angle. I shortened the drag link as much as possible. Does anybody know how long I need to cut the CJ drag link so it works correctly with the Ross bell crank? This is only temporary until I do a P/S swap.
BTW YJ u-bolts and spring plates will work except for one u-bolt. TJ u-bolts are too short.

 

This question is not exactly on the subject but very closely related.
After trying to properly bleed and set 11" drum brakes on a D25 I have given up and decided to go with disc brakes on the front. I found a '78 CJ5 with 1 1/8" discs for the donor. Several articles say to use the hubs from the donor with Willys bearings. The '78 is an open knuckle axle (D30?) and the hubs appear to have a slightly larger diameter on the back side and will not fit my D25 spindles.
Does anyone know of any issues with using my original hubs and disc brakes??? I did a test fit on a spare knuckle and everything seemed to work OK.
Thanks for letting me use this space.
Tommy