Dickinson County Comanche

To answer this topic: I replaced the servo (which was so graciously sourced from @eaglescout526) and it fixed it, so it must be some internal servo failure. IMG_3480.MOV

To update, I’m planning on selling this truck sooner than later once I get a title put on it, but in the meantime I finished the swap all up and even got the interior looking somewhat decent with a shift boot & knob from an S-10

1992? XJ I want to use as an axle donor. I think it’s a posi 8.25 w/ 3.55s in the back but I’m not positive about that.

If the rear bumpers are the same I’d think they’d blend fine, at least on the rear, the fronts might be a problem with the lack of cladding though.

Was helping a friend in North Carolina look for a Grand Cherokee (he has an 80 series Land Cruiser, but was having trouble so I was showing him a good 4WD SUV) and came upon a ZJ being parted out with a set of splash guards, and since I have no self-control, I bought them. I like the way they look, and I also like how it holds on my corner piece of cladding so I no longer have to fix the rust underneath it.

Upon further review I might just buy the whole axle to swap in. That was my plan with the rear axle anyway since I have a complete 3.55 Dana 35 Comanche axle laying around.

Could I just go and pull the entire carrier, shims and all, and just plop it in you think? I’d rather not try to shim it right, though I’ve thought about getting a 91+ front axle to have the non-disconnect axle too, but that’s a lot more work

Another yearly/6 month update: I missed a few things on my last update, I installed wing windows and a set of front bumper guards from a 1990 Cherokee, as well as cruise control. Still trying to get it to work properly, but it’s all installed. Looking to try and swap the gears to 3.55s. My 5 speed ZJ has made me spoiled with its 3.55s so I’d like to swap. I have the rear axle already just need a front axle carrier. Been super reliable still, just about to hit 140,000.

Either way, I’ve tried 2 different reservoirs to no avail. Unlike the climate control it won’t have any vacuum at the servo after like a minute or so after you shut it off, indicating to me that it probably has some sort of internal leak, given how the vac line is brand new and has been leak tested multiple times, and the other vac bubble didn’t help.

It holds vac. Granted I have to blow into it vs suck on it to tell, but it holds vac, yes

Jumper wire didn’t fix it. Putting more vacuum to the servo didn’t fix it, putting less vacuum to the servo didn’t fix it. I even took the ground off the servo and it still didn’t fix it (cruise did still work, maybe something wrong there?) but I’m probably just going to get a different servo and see what happens. It’s the only thing I can think of being truly faulty here cause it’s getting good vac, consistent vac, brake pedal isn’t bleeding vac back, 2 different control modules didn’t do anything, and I know the speed sensor is most likely functional given how it will try to hold a constant speed, just it can’t meter itself right so it slows way down then floors it to catch back up, just to immediately pull all throttle out and it slows way down again. I didn’t think it would be this much of a hassle

So you think the clutch switch is defective then? I can try bypassing it with the little jumper thing the autos use

No, swapping them would be quite difficult given their sizes. One is a 1/4” and ones probably a 5/16” or 3/8”.

I almost feel as if the servo isn’t holding the speed proper. It’s like it’s letting it slow down too much and then trying to catch up, not the other way around.

Brake pedal end will move the diaphragm, the other side won’t.

Something, but not what’s causing the problem. Is the servo ok vacuum-wise though? I feel like the other side should hold vacuum but doesn’t. If you pull enough vacuum tho it will start to move the diaphragm within it.

I did notice while poking around that the cruise cable wasn’t fully clicked into place, and that the larger bleed hose might have been leaking when plugged in, but not when testing. I’ve remedied both so we’ll see if that happens to fix anything.

Ok, so I tested it using plugs and here’s what I found: The larger (Bleed?) hose going to the pedal will hold vaccum. The larger port on the servo side will not hold a vacuum. Both smaller sides, going to the vac bubble and the servo side, hood vacuum just fine. Just to recap, the one with the hose connected (not the same truck but still applies) does not hold a vacuum within the servo itself. The hose does with the pedal switch, however.

I have a vac gauge. Do you know how much mercury it should pull? I’ve tried 2 separate vac bubbles so far and nothing has worked.

I also tried a vac restrictor just for grins and it didn’t seem to help. It’ll hold speed perfect going up or down steeper hills, just flat ground or smoother hills make it do the whole on-off-on-off type feeling it makes. the servo also makes a lot of noise at low speeds

Should the Servo hold vacuum at the dump valve connector? The hose with the pedal on the end is fine, no leaks, but the servo side just blows thru with little to no resistance. The other port (little line) holds vac pressure just fine.

Hey all, added cruise to my Comanche and I’ve run into the problem where it wanders in terms of speed. If I set it at 55, it’ll speed up up to 60-65 then slow back down, over and over. It’ll also occasionally sometimes slow down to 50 before taking back off again. I’ve tried adjusting the module screws for about 2 hours and used 2 separate control units to no avail. Also, if anyone has a Comanche with a manual and cruise, I’d like to see how your screws are set to get a baseline of sorts.

I have the rear two, just looking to get the front 2 and whatever brackets (if they even had any) to mount.

My manual ‘94 ZJ. 325k on the clock and still starts & runs like the day she was built

Got the swap somewhat finished up. Test drove it and it runs amazing! Too bad it was dark & 8° or else I would have videoed it.