View Full Version : Early XJ questions - What have I gotten myself into????

September 28th, 2017, 17:37
Haven't been around for a while but with a new XJ comes new questions. And do I ever have questions. Lol.

Been in the XJ/MJ game for a few decades now so I've learned a thing or two over the years. However I just picked up an '85 and that goes back a bit further than my experience. Super familiar with the '87-'90 and '91-'96's but know very few specifics about the first generation rigs.

Jeep in question is an '85 2 door, 2.5, 4spd, 4x4.

Should be AX4/NP207/D30/D35 with probably 3.73 gears correct?

More important questions right now though:

Is the steering column (and it's internal components) interchangeable? Seems to be a turn signal switch issue.

Is the heater control interchangeable? Issues here as well.

And... Interior door panels? Interchangeable up to '96?

Is there a good thread anyone knows of that covers interchangeability between the generations? I tried searching without much luck.

Thanks in advance, any advice or input is much appreciated.

September 28th, 2017, 19:20
The 85 2.5 was a single carb engine barely pushing 105-HP. Diffs should be 4.10/4.11 with the 4-cyl. 3.73 was seen in some early 6-cyl. The D35 will be the non-clip version, which in my opinion is stronger and more reliable.

October 2nd, 2017, 07:13
Diffs should be 4.10/4.11 with the 4-cyl. 3.73 was seen in some early 6-cyl.

4.10/4.11 in 4cyl 5spd, yes. My sources say 4spd is likely 3.73. While I haven't yet verified on this jeep I have seen this on another '85 in the past.

Green Mesa XJ
October 2nd, 2017, 14:37
Heater control switches are unique to 84-85, steering column is 85-90 mostly because of the keys, 84-94 works.

Most of the 87-90 are very similar, door panels, seats, and wiring can be swapped in. The early dash and engine harness are unique to 84-85, body harness and things like door looks interchanges at least to 1990.

Heater control might swap out with newer if the vacuum harness is swapped to. Not sure about the plugs.

Np207 is a decent transfer case in my experience, it also has a thicker drive chain.
Should have the vacuum disconnects on the front axel.
Dana 35, not a fan, broke at least 3 on my 1985 XJ. Went though more than that trying to find a good 3.73 ratio axel.

Ax4/5 is alright in these jeeps, not enough power to bust em. Also slightly different builds than later ax5 may actually be be tougher.

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October 2nd, 2017, 17:32
Thanks Green Mesa XJ.

Sucks about the heater control. I have 3 newer ones here on the shelf but no vacumn harness to go with them.

Thanks for confirming steering column interchangeability... I have turn signal and ignition switch issues so a complete column swap is likely the easiest fix.

As for the drivetrain, it's all pretty familiar. Even ran a 207 in one of my MJ's for a while without any issues.

Green Mesa XJ
October 2nd, 2017, 17:57
Glad to help. I like these older XJ but they are unique in their challengers. I put mine through hell the other jeeps havenít seen, except for the Dana 35 it handled it all well despite not having the reputation of the later XJ .

Just remembered the plug for the heater control are the same as 86 up, I had to put a newer dash harness in my 85 cause the fuse box was ruined, the existing heater control plugged right in.

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October 3rd, 2017, 06:08
The steering column internals are also interchangeable with many GM ars and trucks of the era.

October 3rd, 2017, 06:09
Also watch the clutch master as it has a tendency to leak into the fuse box and wreak havoc with the electrical.

October 3rd, 2017, 08:47
My rig started off as a 2.5L with the Carter YDA computer controlled carb. I upgraded to the TBI injection from an 86 and it made a TON of difference. I had to find a way to add a CPS so at the same time I upgraded from the AX4 4 speed stick to the later AX5 5 speed stick. I added a Mopar "Purple" cam. It was great for rock crawling and could hold 85 on the freewave but didn't have the power to handle the high mountain passes here in Colorado to my liking.

I ended up building a 4.7L stroker and swapping it in. It took some metal work and changing over the hood, but it has been great. I've had my rig, or what's left of the original, for 21 years.