Flat towing with hydro assist

Recently installed assist on my XJ. PSC ram 3/8" hoses blah blah blah. Still running a D30 locked on 35' with beadlocks.

Never had an issue flat towing before the hydro assist. Now when I do, the jeep wants to turn passenger and stay. I tried unbolting the ram, no dice. Adjusted the toe a bit, nothing. I'm stumped as to why it won't flat tow. It drives fine on the street. I even had someone pull the jeep with me in it and the steering is not following the tow vehicle. I had to constantly correct it to get it to follow

Any ideas? Or is flat towing just not in the cards?

Brake caliper dragging or maybe a broken center pin making it crab?

If you don't have enough caster, flat towing can be a big problem.

old_man said:

If you don't have enough caster, flat towing can be a big problem.

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^^This^^

Have you called PCS?
They have the technical knowledge that we don't have.
The fluid flow pathway has been changed and you need to know the effect.
Possibly having an inline on/off valve, on one of the ram hoses, will restore the steering's centering, the ram appears to be disrupting this characteristic.

When you rode in the XJ, while being towed, did you try starting the engine to see if hydraulic flow is necessary for the steering to function normally?

I have towed our XJ over 60,000 miles, sometime with the alignment completely wrong and never had a tracking problem.

If the ram has been mechanically disconnected, about the only thing left is Caster.

If your XJ flat towed OK before the ram was added, then it should still do so unless something is unbalancing the steering.

I assume you are using a PSC single ended ram and not one of their expensive double ended cylinders. Something like this?
http://www.pscmotorsports.com/95-02-jeep-tj-xj-yj-extreme-cylinder-assist-kit-no-pump.html
When flat towing and the engine is off, fluid is moved through the steering box during turns.
Normally, the pressures even out when turning from left to right. Porting the box and adding the ram may have thrown the balance out.
Single ended hydraulic rams, with the shaft exiting on one end only, do not produce even pressures, in and out, when pushed or pulled or when pressurized.

Why? On one side of the ram the shaft covers part of the piston, while the other side the piston isn't covered.
This means the side with the shaft has less piston surface area and pushes and pulls less fluid, when being towed, than the side without the shaft.
This effect is real and one of the first things taught in a hydraulic design and maintenance class.

The ram's uneven flow and pressure, from side to side, may be causing the pull.
It doesn't take much to push it to one side.

Do let us know the solution, have considered doing the same to my flat towed XJ.

Yes a single ended PSC ram

Flat towed fine before the ram. So I know caster isn't the issue. I mechanically disconnected the ram but it is still hydraulically connected so when the steering gets pulled one way, passenger, it's stays as there is not enough pressure that can be applied without turning the wheel to correct the steering.

I'm just thinking out loud but I think the only solution is to bypass/disconnect the hoses to the ram. Like lazy was just explaining. Even when unbolted the ram would stop in the contracted position and not be able to expand without steering wheel input.

And yes I tried having the jeep running while being towed with no better results. I know it may seem like I'm answering my own question but I haven't heard of this issue or a good solution to it

^ This ^

That's the plan. Just was hoping it wasn't something that would be an absolute necessity. But I've been browsing CL for a while now

Pulling an 2000+lbs extra, because it doesn't steer right when towing, seems like high price to pay, both weight and money wise.
One high-pressure valve would eliminate the ram from influencing the steering, while towing.

Guess it depends on how you use your XJ.
If it is a off-road toy and you use it hard, a trailer is the only way to go.
I owned VW buggies for years and having a trailer was great to have after blowing up a transaxle, in the Glamis sand dunes. It also had storage for extra tires and whatever.
If your XJ is more of a driver or expedition setup, flat towing can work just fine too and has it's own advantages.

I would rather tow 4000-lbs than 6500-lbs but a lot depends on what you will be pulling the loaded trailer with. Got a Power-Stroke diesel, your are in good shape, either way.
If you have a motorhome with a gas V-10, like our E450 based motorhome, 2000-lbs is a lot to add. 305-HP only goes so far when the total combined weight reaches 18,000-lbs.
Why Ford never installed a inter-cooled, turbo diesel in the E450 is a mystery.

Having towed both way, flat vs. a twin-axle car hauler, I would pick flat any day, it's a lot more stable, assuming that you are not out to play and damage is a very real possibility.

Towing flat keeps the Jeep from being pushed around by cross winds or bad roads, the way the trailer does. The Jeep's suspension works well when it's being flat towed.
We have towed our XJ behind our motorhome for about 60,000 miles, over the last 12 years, without any problems or failures that would keep it from being towed.
A lot of those miles were on poor backroads.

A problem for travelers, who use campgrounds, is where do you park the trailer, if the Jeep is removed for use?
In many BLM and FS campgrounds, finding a site deep enough for a 24' RV and a Jeep can be challenge, especially in older campgrounds.

Having a true neutral in the transferase make it possible as long as the axles still rotate the way they should.
Spare axle shafts are carried in the motorhome. Spare bearings and hubs are stored in the Jeep.
So far, so good.

I have to disagree with the above statement. In my experience even an 8k lb plus trailer pulls better than a 4k lb vehicle being flat towed. A trailer tracks straighter, the wheels don't try to follow grooves in the road, it can be backed up easily, and if you break drivetrain components while wheeling the only fight is getting the jeep back on the trailer.

zachandandy said:

I have to disagree with the above statement. In my experience even an 8k lb plus trailer pulls better than a 4k lb vehicle being flat towed. A trailer tracks straighter, the wheels don't try to follow grooves in the road, it can be backed up easily, and if you break drivetrain components while wheeling the only fight is getting the jeep back on the trailer.

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I agree with the backing up and parts breakage issues, that's why I mentioned carrying the needed spares.
Through experience, I have learned to watch the road ahead carefully to avoid having to back up and almost never have problems.
I also don't beat the XJ hard, it's not a toy or a competition vehicle.
My usage is probably much different than yours.

We must be comparing two different types of tow vehicles, Towing an 8000-lbs trailer indicates a large engine with big power.
In motorhomes, only the big diesel pushers have the big power available for pulling heavy trailers, plus the weight rating to do so legally.

As to for when flat towing MY 4000-lbs Jeep, with a 14,000-lbs motorhome, the XJ is not noticeable, except on the uphill and downhill grades.
It has been pulled throughout the western parts of North America, on every imaginable type of road that the RV can travel and done so in all weather conditions, without any hint of wandering or tracking.
If it was wandering or not tracking, it would be noticeable in the rear view camera monitor and by the seat of my pants. It doesn't do it.
The Cherokee doesn't wander when driven on the street either.
Thousands of other RVs flat tow their Jeeps and 4X4s too without the wandering problems you report.

My key to keeping it tracking straight is a tight tow bar arrangement and making sure the XJ's steering and suspension are tight and in alignment.

After 12 years and 60,000 miles of flat towing the XJ, all I can say is my experience has been much different than yours. YMMV

meh. the cost of a used trailer is the same as the cost for legally setting up flat tow, but with easier towing and less concern.

i'll be happy if i never flat tow a vehicle again.