Flat Towing an FJ55

[Bizzle77]

So I got my ol' landcruiser FJ55 ready to flat tow down to the Toys for Tots trail ride near Rochester MN yesterday, but as I was pulling out it wouldn't track around corners...the front tires wanted to stay straight and even turn the opposite way...

I have flat towed this vehicle several times before using an E350 with no problems...I even have a tow bar mounted and dedicated to the FJ...

This time I wanted to take my bronco so I could have two 4x4's...twice the fun...

I have towed my FJ55 on a car hauler with my Bronco several times with no problems...including a trip up from Nashville to Minneapolis...not an option this year however since I don't own that trailer anymore...

My troubleshooting:

The first thing I noticed is that the tow bar angled slightly up from the tow hitch of the bko to the bumper of the fj...I thought maybe it was having a downward push as I pulled it along...so I flipped the receiver and ball so the tow bar sloped slightly down...this helped a little bit...and now I can get it to track if I take ridiculously wide turns...still not safe for highway though...

The fj front hubs are unlocked, transmission in neutral, transfer case in neutral, no steering lock exists, the steering wheel turns normally by hand, and no components seem to be binding...

tracks straight when going straight...

The difference seems to be in the tow vehicles...

My 2002 E350 has an open 10.25 sterling...wheel base is 138 inches...

My 1993 Bronco has a limited slip 10.25 sterling...wheel base is just under 105 inches...

My 1977 FJ55 (TOED) has open differentials...wheel base is about 106 inches...

Wheelbase:

In your experience, will the difference in wheelbase from the tow vehicle to the toed be a factor in how the toed tracks around corners?

Limited Slip:

Since an open differential allows the tires to turn in equilibrium when both have traction, the pivot point for turning is somewhere close to the rear differential...on the other hand, a locker doesn't allow the inside tire to turn slower than the carrier and tends to position the pivot point somewhere near the inside rear tire...I'm not sure if my ford factory limited slip acts more like an open or locked differential when turning...

So, second question, In your experience, can a limited slip effect how the toed tracks around corners?

Thanks...I wouldn't want to miss another weekend of wheeling...

 

[inkpot]

Howdy! Is the original steering column lock removed? It sounds more like the caster has been way altered so it does not track properly. How does it drive on the street?

 

[Bizzle77]

thanks inkpot,

the steering lock is removed and i can turn the wheel by hand regardless of key position...

it could be caster as i can see the leaf springs do have some fatigue/wrap...but the axles are mounted in their original sua configuration...all stock...

other than it being hard to steer due to no power steering, it tracks straight when i'm driving it...and it has been flat towed before...

the only thing i can think of is the closeness in wheel base or the limited slip in the tow vehicle...but i don't understand why either of those things would actually have an effect on the toed vehicle and how it tracks when turning...

any ideas?

 

[inkpot]

thanks inkpot,

the steering lock is removed and i can turn the wheel by hand regardless of key position...

it could be caster as i can see the leaf springs do have some fatigue/wrap...but the axles are mounted in their original sua configuration...all stock...

other than it being hard to steer due to no power steering, it tracks straight when i'm driving it...and it has been flat towed before...

the only thing i can think of is the closeness in wheel base or the limited slip in the tow vehicle...but i don't understand why either of those things would actually have an effect on the toed vehicle and how it tracks when turning...

any ideas?

If the caster is anywhere close to where it should be, then it should follow the leader just fine. The pivot point should be well behind the vertical axis of the trunion bearings. Hmm...... Any lockers in the Piggy that could be stuck/dragging?

 

[Bizzle77]

yeah, i was hoping it would track...but no...weird...and kind of a bummer...

and you are right, the pivot point for the steering on the FJ55 is at or slightly behind the trunnion bearing...

but im referring to the pivot point of the towing vehicle and how it might be effecting the toed vehicle's ability to track in turns...

here's my thinking...

if the pivot point is at the differential, then the inside tire will fall behind and give a directional force to the tow bar in the direction of the turn...

on the other hand, if the inside tire doesn't fall behind, and the pivot point is somewhere closer to the tire, then the tow bar will be pulled forward instead of in the direction of the turn...

ill try and come up with some drawings so you can help me figure out if this makes sense...brb...

 

[Bizzle77]

Does this make sense?

 

[inkpot]

I understand your idea, but your WAY over thinking it. Even if you tow it with a golf cart, the 55 should follow the ball on the hitch. It doesn't matter what the towing rig is setup like, or how it drives. The pivot point is at the hitch ball regardless. You could even use a farm tractor with steering brakes and the results will be the same: it follows the ball. Is there any chance that you have raised or lowered the hitch ball a bunch between different tow rigs? Pulling up or down steeply could affect the steering on the 55. John

 

[Bizzle77]

I think you are right...it should follow the attachment point (ball)...

on the slope of the tow bar, I did notice a slight improvement when I flipped the receiver...now the ball is higher than the tow bar mount points on the FJ55...and seems to track slightly better...still not safe though...

If I remember correctly, the ball on my van is just a bit higher than the FJ55 mount points as well...

the rise is not very steep...but noticeable...

I'm stumped...I think i'll try it with a buddies F350 crew cab and see what it does...

thanks inkpot...

 

[Bizzle77]

I totally forgot that I have flat towed a 1989 F350 crew cab with a 1989 Bronco and the truck tracked just fine...it was a little sporty pulling all that weight but the difference in wheel base didn't effect how the toed tracked through turns...

and since the FJ55 tracks when I tow with a truck with an open differential, that suggests that it's the limited slip that is the only difference...

has anyone towed with a limited slip in the tow vehicle? anyone have any similar problems?

 

[DaveWest5150]

think of it this way...the distance from the rear wheels to the hitch ball (on the towing rig) may differ, so from a stand still, if you turn hard right the the hitch ball swings hard left, causing the wheels to "want to turn left .. but begin to be "dragged" to the right. I have learned.. that if you tend to roll into a corner the wheels will follow in most cases. I noticed it most with my motorhome (the dist from the axle to the hitch ball is around 12 feet) if I were to turn hard right my 40 would lock to the left. then I "modified my driving, by stopping a little before the corner... and before turning.. I rolled into it. this nearly eliminated the problems I was having. try it ... see if it helps.

 

[Bizzle77]

thanks for the input inkpot and davewest...

as it is it definitely does help to roll into a turn and take it a bit wider than normal...thanks...

i have a similar thread up in fsb (a bronco site) and everyone is pretty sure it's my caster there too...

after looking at it, i'm pretty sure it's at 0 or maybe even slightly negative...

i should mention that when driving it on the street it does track straight, but the wheels don't return to straight after a turn without a little help...and that's definitely caster...

so i guess my only decision now is do i fix it with a $10 shim or go ahead with a soa config...

thanks again everyone!!!