Hello group.

I'm new to all things Jeep. I recently bought a 94 YJ with the 4.0 as a father/son project since my son is turning 16 this summer. Hopefully we'll get it fixed soon.

When I drove the Jeep home there was "clunking" coming from the right front. I found that the front wheel bearing was shot and that the front axle u joints were bad. I have replaced both front axle u joints and both wheel bearing assemblies. There is still a clunk when driving, mostly when turning left. I checked the vacuum for the front wheel 4wd engagement with a vacuum pump and it seems to be OK.

Here is the question: when in 2wd what port on the diaphragm is suppose to have vacuum? Where does this vacuum come from? How is it controlled?

I'm sure that there will be more questions later.

Thanks,
Greg  

Check the bushings in the trac bar. The trac bar clunks when the bushings get worn and there is side force as there is when turning.

Also, check the sway bar links and the sway bar bushings. They click when worn. The sway bar also gets loaded when turning.

Check the u-bolts for the leaf springs and also the bushings in the spring eyes and the shackles and hangers.

The front axle disconnect is problematic. There are kits to sleeve the two piece axle and a cover so you can remove the servo. Jeep stopped using the two piece axle with the TJs and it is basically the same front. Nobody notices any differances in fuel economy with the sleeve kit. Some might argue the unnecessary wear issue, but TJs are your reality.  

I shouldn't call it a sleeve. It's a one piece axle and cover. There is also a cable operated replacement for the vacuum servo made by Posi-Lok. A new servo from Chrysler cost $280.

Here is what Posi-Lok says:

"The OEM unit is vacuum controlled. This vacuum system is prone to failure due to frozen diaphram, loss of vacuum, hard or cracked vacuum hoses, or complete loss of vacuum lines.
The OEM unit has demonstrated a high rate of failure, is non-repairable."  

I agree with ftgiles. First thought is simple of the steering components.  Have (insert son'e name) sit in the pilot's seat and turn the steering wheel back and forth, as you visually and physically check/feel for any slop/looseness/clunks/rubs in all of the steering componants.  Do this safely!!! The u-bolds for the suspension are a candidate as well.  Do you get the death-wobble around 50-55 mph with a jolt of a bump in the road?  

I don't know if there will be a death-wobble, haven't gone that fast since we finished the wheel bearing and u joint work. Just once around the block.

I'll check the steering system as suggested.

I did some searching and ordered a posi-lok and fork from "Oconee Off-Road" to replace the vacuum system on the front axle. I spoke to a neighbor that has a Jeep and a mechanic and they agreed with the postings here and said to replace the vacuum system.

I'll update after the install. 3-4 days

Thanks for the input from all (both) of you.  

Good to replace the fork too. They wear out. I think the one from Posi-Lok is steel and not aluminum (last longer).

Also, gear lube in the disconnect housing is proned to getting gummed up, preventing the servo (not enough strength) from sliding the collar to lock the axle.

So, make sure the inside of disconnect housing gets cleaned.

Change the diff oil front and rear and the transfer case oil while you're at it. These are usually neglected areas.

I'm not really addressing your problem directly. These are all just things to check out. Sounds like maintenance hasn't been kept up prior to your purchase.  

Make sure you attach the cable where it will not move the WHOLE cable. Just the inner. Also, make sure the fork is turned the right way.....You laugh, but I helped two Jeeps a few weeks ago with these problems on the trail. Mine worked like a charm. Nice being able to put the tcase in 4 low and still be able to turn.  

Samiam99 -

Just thought you might be interested in this from the FSM. It is found in the text for the front axle DIAGNOSIS AND TESTING section.

LOW SPEED KNOCK

Low speed knock is generally caused by a worn
U-joint or by worn side-gear thrust washers. A worn
pinion shaft bore will also cause low speed knock.

Differential side gears and pinions can be checked
by turning the vehicle. They usually do not cause
noise during straight-ahead driving when the gears
are unloaded. The side gears are loaded during vehicle
turns. A worn pinion mate shaft can also cause a
snapping or a knocking noise.  

Well you are right on!

While waiting for the posi-lok to come in...

Yesterday I took the rear differential cover off to fix a gasket leak. I found that the spider gears are mashed up and that there are metal chunks all over the place. The "clunk" was caused by the rear differential locking up and then snapping into place. Scary!

I am looking on e-bay and craigs list for a complete dana 35 set up. I priced the new parts seperatly and it is close to $600 for the works. Local shop gave me a $~900 quote for parts and labor, ouch. My chilton manual does not give instructions on how to do a complete overhaul, probably better off since the tolerances are really close from what I have been told. I don't know if I could do the job myself but if I can find the parts cheap and then have a shop put them in or replace the entile axle setup... we would be OK.  

I have a complete Dana 35 with 3.73 gears. Has 25k miles on it. Should be less than $200 for a gear setup if you want just the diff and gears. Cheap. Just sitt'n around here tak'n up space. Interested?  

Send me your contact info, if interested. Click on my user name to get my e-mail address.