Jeep Wrangler Caster Setting

[Mike Canter]

I think that by 1997 Jeep Wrangle is wearing the tires out too fast while being towed. I chacked the alignment and I had +6.2* caster on both sides. This may seem a lot to regular car owners but is within the +6 to +8 limits of a Jeep with coil spring suspension. I had read somewhere that to have a car track better and stop tire scrubbing while being towed to increase the caster by some amount. I can't remember what that amount is. Does anyone know?

I have increased the caster now to the max of +8* to see what happens. The only thing I noticed was the steering wheel spins back to centerline a little faster after going around a corner.

Has anyone played with a Jeep Wrangler with coil springs suspension and found what the best caster setting is for towing? Any thoughts would be appreciated.

[porscheracer]

You have discovered what caster does - centers the wheel. The downsides - it makes it a little more twitchy going backward and a little harder to turn . . . although with power steering it's not an issue.

Depending on the wear pattern . . . tire wear is usually a function of toe and camber more than caster. I'd try setting the camber and toe as close to 0 as the specs allow.

[Mike Canter]

Thanks. The wear is absolutely even across the tires. No unusual wear pattern. The camber is at -0.4* on both wheels and the toe-in is right on. I tested the Jeep backing up and it seems like no problem and of course I never back it up attached to the MH.

As an extreme I use +10* on the drag racing car to keep it straight down the track at high speed. If you are not careful backing up on the strip it will jerk the steering wheel out of your hands and the car will do a real quick 180* turn just like what Robert Mitchum did in the movie Thunder Road.

[wilanddij]

Tire wear on a toad can also be a function of the steepness your towbar angle. If your MH connect is much higher than the Jeep's, you may be lifting the front end and scrubbing the tires. Blue Ox says the toad should be between level and 4" lower.

[John90XJ]

A lunchbox locker or limited slip diff in the front maybe?

Toe should be set as close to ZERO on this front end as possible

[Mike Canter]

Nope, no front locker. Here is what I did. The front caster range on that 97 Wrangler is 6.0* to 8.0* and it was set at 6.2*. I turned the concentric caster adjuster bolts 90* so they were at their max and measured the caster again and it was now at 8.0*. On the last trip I noticed no scrubbing. The Jeep is following the MH better. I actually like the way the Jeep drives now. It likes to stay in a straight line and high crosswinds don't bother it as much. The toe-in is at 1/16".

[CARVAL Motorsports]

Funny, I keep running into the same people here?!

I was going to drop a new post asking about a Wrangler as a toad. This seems to answer my question as to whether it would be a decent choice. We are looking at several used Jeeps right now. Can you tell me anything else Mike? I do remember several years ago, a good friend towed his Jeep Wrangler and did experience the same tire wear issues. I am assuming that your unit is a manual.

Towing a vehicle is going to be somewhat new to me as I have just pulled trailers before. From your post, I see that backing up with a toad is not a good thing, true? Or maybe just minor rear movement? So that means you get close to where you are going and disconnect, correct. Anything different because of a tag axle? If there is a Toad cheater sheet out there, maybe you could guide me to it.

[porscheracer]

Carl . . .

We were investigating getting a Wrangler to use as a toad for the View (at 4500#, the Dakota is a wee bit more than it likes). An hour-long trip on the interstate convinced us of the error of our ways. Since serious off-roading wasn't really in our plans, we ended up ordering an Escape AWD - less $$, more comfort / economy, lighter.

We back up all the time with the Dakota. You just have to remember that once the negative caster takes over and the wheels start to go off-axis, you're done. With any luck, 100' or so is a piece of cake.

The toad is easier to tow forward. It takes a radius much more like the MH.

I've been visualizing an electro-mechanical caster adjuster for toads - where you filip a switch to "reverse" and it goes to about 8* negative caster.

[Mike Canter]

Carl, the only problem I have had towing that Jeep was that tire scrubbing.I bet I have towed it 40,000 miles. I have seen it written several MH Magazine tech sections that adding caster makes any vehicle tow better. It was not a big deal to adjust the caster.There is a bolt on where the lower arm attaches to the axle and in has a lobe attached to the bolt head. That lobe pushes against the arm. I marked with a dot of paint where it originally was. On my Jeep it was straight up which is the neutral position which is 6*+ caster. I loosned the lock nut and moved the bolt head 90* which is max. That changed me to a 8*+ caster.

Yes, I can also backup if the MH and toad staying a straight line. If either one turns it is over. I have gotten myself into a couple of situations where I have had to disconnect to get out.

[Bruce H]

I just got back from the tire shop because my 2000 Jeep Cherokee had a tire flapping sound. It was due to the front tires cupping. They recommended rotate the tires every 3000 miles. I had a bout 7000 miles towing. I have a Blue Ox tow system and wonder if I should investigate the caster or toe in etc. My MH has a 12 foot over hang and I thought that was the problem, and it may be. I do like having the 4 wheel drive as I am not limited to where I can go.

[Mike Canter]

I was not seeing cupping on the front tires. I was seeing them wear evenly fast. Normally cupping is caused by a bad or worn suspension parts such as shocks or ball joints. Depending on the type of cupping it can just be because the tire was out of balance for a long time. Once they start cupping they just get worse. Cupping will not be fixed by increased caster.

Try this http://www.goodyeartires.com/kyt/maintainingATire/#2

[Bruce H]

Thanks for your input Mike. What is puzzling about the cupping is I didn't seem to have the problem until I started towing. The Jeep has 80,000 miles and has not been abused off road. I did check out the Goodyear site and they suggested much of what you did. I will have the Jeep checked out for worn front end and maybe I do need shocks.

[Mike Canter]

Bruce, a little more caster really helps keeping the toad in a straight line behind you. I believe that 1 to 1.5* increase is what is recommended or to the high end of the specifications of your vehicle. The only thing it might do is make it a little harder to turn a corner if you are driving the SUV by itself. I didn't notice an difference in my turning. It also helped the MH a little in crosswinds and when those #$%$ trucks sneak up alongside of you. I guess the Jeep is not being affected as much by the winds.

As far as your Jeep is concerned maybe 80000 miles is time to change your shocks or at least do a bounce test on them. Take a flashlight and see if you can see any evidence of oil and oil soaked dirt on upper part of them where the rod goes into the shock. I just changed the front struts in my wife's BMW at 140,000 miles and they were totally gone.