Building an XJ for towing - input wanted!

[ChaseN]

Hi everyone

Just wanted to get some of the forum member's opinions on building up my XJ for towing. I'll be towing my 911 track car + trailer - race weight on the Porsche is 2750lbs, trailer is 1100, plus about 300 pounds of tools/rain tires/incidentals, for a total of around 4200lbs or so loaded (reaalllll close to the XJ's 5000lb rating). Tongue weight around 400 lbs (its hard to get much more since its a rear engine car. Don't know if this will be an issue or not, but I guess I could put the tires and tools up front if it needed more). The trailer is an open tandem axle with electric brakes. I know the XJ really isn't the ideal vehicle for this, but its what I got, and I'm NOT giving it up for a pickup (plus, a guy I race with tows his car behind a 6 cylinder 6-speed BMW wagon, so I figure the cherokee must at least be equal to that). I used to drive the car to the track, but some modifications this winter put it firmly into the NOT street legal category. I'll be towing it about 1-2 times a month during the spring/summer/fall (as far as 5-600 miles one way) and probably not at all during the winter.

I'll start off by telling you how my XJ is setup now -

-144k miles
-Around 20 psi of oil pressure at idle, 45+ at speed
-245/75/16 MTR's on Moab wheels (off a LJ Rubicon)
-2" budget boost up front
-2" OME HD lift springs in the rear
-RE monotube shocks
-Brand new 2 row radiator, water pump, 190* thermostat, fan clutch, serpentine belt, hoses (basically I went through the entire cooling system)
-Brand new headgasket (explains that ^ )
-Stock gears (I think 3.07s?)
-Cheesy class I hitch
-97+ intake manifold

I pulled an appx. 2100 lb trailer (without trailer brakes) back from Chicago to VA with this setup, with no problems whatsoever, except LOTS of downshifting in the PA and VA hill country.

Now for what I plan to do to the XJ -

-Centerforce dual friction clutch/pp. From what I understand, the clutch is the weak link that caused the massive difference in tow rating between AX15 and AW4 equipped XJs. I'd rather not burn a clutch up if I can avoid it.
http://www.centerforce.com/clutches.tpl?cart=12673321522841941&subsection=clutchselector&searchStr=csearchStr3&cstep1=step1&cstep2=step2&cstep3=step3&carmake=JEEP&carmodel=CJ%2C%20DJ%2C%20TJ%20%26%20YJ%2C%20CHEROKEE%2C%20COMANCHE%2C%20DISPATCHER%2C%20SPORT%20WAGON%2C%20WAGONEER%2C%20WRANGLER&caryear=1992
-Air lift airbags. I HATE the look of a rig squatting in the rear. These claim to increase the level load capacity by 2000lbs.
http://www.suspensionconnection.com/cgi-bin/suscon/59507-cherokee-air-springs.html
-Vanco hydroboost kit. This claims to increase the pressure at the master cylinder by 2-3 times. Braking is GOOD with 4000lbs + behind you.
http://www.vancopbs.com/category_s/76.htm
-Grand Cherokee rear discs. Again, just a good idea.
-Real Class III hitch. Probably just go get one installed at U-Haul. Necessary for the trailer's weight.
-Weight distributing hitch. Pretty self evident.
http://www.amazon.com/Curt-Manufacturing-17300-Distribution-Trunnion/dp/B001EOV4II
-Tekonsha Prodigy brake controller
http://www.etrailer.com/p-90185/Tekonsha-PRODIGY-Brake-Controller---Proportional.html
-Re-gear. I'm thinking about going to 3.55s, maybe 3.73s. Opinions? I honestly don't feel my Jeep is lacking power as it is (even with the stock gears and 31's) and I'm afraid 3.73s might be a bit too much gear when I'm driving around without the trailer (which will be 90% of the time). I've got the factory Chrysler 8.25 (thankfully) so I think I'm good there.
-Redline MT90 tranny fluid. Keep the manual tranny good and lubed/cool.Supposedly safe for yellow metals as well.
http://www.redlineoil.com/product.aspx?pid=46&pcid=7
-Redline shockproof 75w140 gear oil. Again, keep her good and lubed/cool.
http://www.redlineoil.com/product.aspx?pid=43&pcid=8
-Unibody stiffeners. I'm looking at the TnT items. I figure the 18 year old unibody with nearly 150k on it can take all the reinforcing it can get.
http://tntcustoms.com/uni-bodystiffeners-2.aspx
-Some sort of free flowing exhaust. Not looking for extra power or sound really, rather I'm under the impression that uncorking this can help keep water temps down. I can also get rid of the cat as I live in a non-emissions area.

Sorry for the looooong post guys. Just want to get everyone's opinion on all the different modifications I'm about to do, as I'm about to sink a couple grand in, and want it to be done RIGHT. My #1 priority here is safety (well, mayyybe #2...#1 is keeping the XJ ), and want to make sure I'm thorough and have a good understanding of what I'm doing. Any and all opinions are welcome - good, bad, I'm crazy, sell the XJ and buy a Silverado, etc. Let me know what you all think!

Thanks

Chase

 

[MT Mike]

I'm moving this one to the tow rig section, as I feel you'll get some better feed back there. :thumbup:

 

[ChaseN]

I thought about putting it here, but I think I misunderstood the part about "NOT related to XJs and MJs". I gotcha now.

Thanks Mike!

 

[tbburg]

I don't think 4.10s would be too low for your rig, especially towing a one ton trailer. Stock gearing for the Wrangler Rubicon is 4.10 with a similar O.D. ratio and similar tire size.

 

[ChaseN]

Fair enough, I didn't think about that. Especially considering its a 2 ton trailer.

So maybe 4.10s it is? I had a Rubicon for about a year, and loved the gearing. Duh.

Thanks

 

[xjtrailrider]

Well I actually went this route with one of my 96 XJ's and it worked well although what I towed only weighed in at around 3500#.

Here was my build;

OME HD rear leafs, they will net some lift but not a lot. 2" maybe and I leveled it with spacers in the front.

Re-geared to 4.10's, stockish 30x9.5 BFG AT's and added a Detroit TruTrac for added traction in the rain.

I added the largest Hayden tranny cooler that I could find and also a B&M tranny temp gauge and AutoMeter "A" pillar mount to keep tabs on the transmission.

There are lots of engine performance mods that could be added but i kept mine simple, I just went with a cold air kit and the Firepower ignition system.

A stroker would be nice!

And last, get a good hitch that uses the nut strips not just the square washers at each hole, a good controller like the Prodigy and a equalizing hitch.

My XJ towed well with this set-up but would get asthmatic on long hills and breaking was always sketchy in the rain but I never felt that I did not have control over the trailer.

 

[badron]

-Centerforce dual friction clutch/pp. From what I understand, the clutch is the weak link that caused the massive difference in tow rating between AX15 and AW4 equipped XJs. I'd rather not burn a clutch up if I can avoid it.
=================================================================
I say NO. It's not a soft clutch that is the problem with towing but the very poor gearing that is. With 3.07 stock gears you generally have to slip the hell out of the clutch to get a heavy rig rolling. If you were to (((just)) upgrade the clutch this wouldn't help the poor gearing condition. You would then just slip you new clutch to death in short time. I have seen this over and over again.
But you are regearing this will lighten the load on the clutch. I would freshen the clutch But no need to spend big bucks upgrading it.
Also regear will take a big load off your brakes. Particularly if you like to down shift. Downshifting is a dead art I know but still a very good way to slow down,

 

[ChiXJeff]

You definitely want to regear, especially if you're towing heavy. 245/75R16 tires work out to around 30.5" in height. I would absolutely not go lower than 4.10, and considering the weight, maybe even 4.56. With 4.56 gears, you'll give up a little top end speed, but I think your clutch will thank you.

Electric brakes on *ALL* trailer axles. I see you've looked at the Prodigy controllers, they work very well. You might consider stepping up to the latest P3 controller.

 

[88 Wagonman]

From my '91 owner's manual:

Trailer sway control and equalizing hitch required for tongue weights above 350 lbs.

Also, the manual doesn't give specs for class III towing (above 2000 lbs.) with a manual transmission, only automatic. I assuming that you have an AX-15 (didn't see a year posted) I would think that it would handle it. If on the other hand you have a Peugeot BA-10, I would be concerned.

 

[badron]

-Vanco hydroboost kit. This claims to the pressure at the master cylinder by 2-3 times. Braking is GOOD with 4000lbs + behind you.
==================================================================
increasing brake pressure by that much is a waste of time on stock or near stock wheels. It MAY just make them very easy to lock up when road are wet.
A upgraded booster from a late model XJ is all that is generally needed with this tire size and manual trany and a lot cheaper. Side note: I AM so cheap!
Remember once you wheels lockup no amount of extra line pressure will stop you any better.
Also let the XJ stop itself and the trailer stop itself

 

[Johnnie Walker]

LSx/LQ truck motor swap..

 

[ChaseN]

LSx/LQ truck motor swap..

:firedevil

If only! If I didn't already have a massive engine transplant going on in my bmw, I'd seriously consider it. In fact, I may when I'm done with this thing.

And to the poster above, yes I have the AX-15.

And maybe I won't be getting hydroboost. Thanks guys for all the input. I'm pretty confident this will end up in a decent towing little rig.

 

[ChaseN]

OH and by the way, does anyone think more unibody stiffening than just the "frame rail" pieces that tie in the front and back subframe are needed? Its a lot of weight for an XJ...

 

[ARB-XJ]

Stroke it.

 

[Johnnie Walker]

Stroke it.

..That's what she said!

 

[warwagon98xj]

honestly if yo got a porshce and a bmw is a mid 90's 2wd half ton that far outta reach? thing is the 4.0- is a great motor but towing that much youll be running it for all its worth, im not knocking your idea its just that for the $$$ of upgrades your looking at you can grab a mid 90s 1/2 ton with a 5.4, 5.2, 350 whatever flavor you want for about 4k



just a thought

 

[Big Red]

Get a Grander Cherokee a 98' 5.9L ZJ! :roflmao:

Seriously though with a manual and towing, you wanna help it along. 4.10s would be o.k. but I think if you are going to gear it you would be happier with the 4.56 gears. I have a 98' 2 dr 5 speed with the stock 3.07 gears and that gears sucks stock let alone going to a bigger tire, towing, and being in VA with some hills. You will be pretty happy with 4.56 gears if you are determined to tow, you will not miss the top end loss anyways towing. :wave1:

 

[WEJOXJ]

x50 on the re-gear especially if you're pulling it through the hills. Watch your temps too, more so if you don't increase your ratio. Better water pump,radiator and coolant mixture could be needed.

When loaded down at the stock level (tires/gears) personally have noticed how flat the output from the engine can be at 65MPH but I'm up at much higher elevation and may not be much of an issue for you. If you do this long term, I've become quite fond with the idea of a Cummins 4BT (300+ ft/lbs torque) swap with a D60 in the rear.