Author Topic: Tow Bar help!  (Read 998 times)

Online MiniDave

Tow Bar help!
« on: July 15, 2017, 04:55:10 PM »
Looking for inspiration, ideas etc.

I got the tow bar installed on the '73 and we took it for a short run around the block, when we got to the first turn the tow vehicle (Jeep) turned left and the Mini went hard right! Every turn after that it tried to do the opposite.......I rode around the rest of the way in the Mini with my hands on the wheel and it did not work correctly.

anyone?  anyone?

Bueller?
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline 94touring

Re: Tow Bar help!
« Reply #1 on: July 15, 2017, 05:02:43 PM »
Safety chains too short and hooked to something that's yanking it the opposite direction? 

Online BruceK

Re: Tow Bar help!
« Reply #2 on: July 15, 2017, 05:02:55 PM »
Is the alignment on the Mini correct?  I would think if it is way off then the toe and/or caster could be affecting it.
1988 Austin Mini
2002 MINI Cooper S
2007 Triumph Bonneville

Online MiniDave

Re: Tow Bar help!
« Reply #3 on: July 15, 2017, 05:15:00 PM »
safety chains plenty loose.

Just did an alignment on it, everything is right where it should be, car drives straight and true......
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline 94touring

Re: Tow Bar help!
« Reply #4 on: July 15, 2017, 05:27:20 PM »
Everything I'm reading on google points to caster.

Offline MPlayle

Re: Tow Bar help!
« Reply #5 on: July 15, 2017, 05:37:20 PM »
Where is the key on the 73?  Is it in the dash or on the column?  If on the column, is it a locking variety and getting stuck while towing?


Offline 94touring

Re: Tow Bar help!
« Reply #6 on: July 15, 2017, 05:38:11 PM »
Reading more...set the caster positive and try again.

To add further, visualize pushing a shopping cart.  The front wheels have positive caster.  The towed vehicle is essentially a shopping cart being pulled.  But if the caster is negative the front wheels will not track straight when being pushed or pulled by an outside source.  I wonder if you can back it up straight though?!
« Last Edit: July 15, 2017, 05:45:40 PM by 94touring »

Online MiniDave

Re: Tow Bar help!
« Reply #7 on: July 15, 2017, 05:43:39 PM »
I thought I had the caster set right, but I'll get it back on the alignment machine and see.....that was my first thought too but like I said, I aligned it last week and all the numbers came into spec no problem......same specs I always use.

Mplayle, the key is on the column, but it was unlocked, the wheels went all the way right, and when I got into the car I turned them left again - it was not locked.

It has to be something obvious, like caster....there's no reason this car won't tow when so many others do with no problem.

BUT, I would think if the caster is that far out the car would drive weirdly.......
« Last Edit: July 15, 2017, 05:46:21 PM by MiniDave »
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline 94touring

Re: Tow Bar help!
« Reply #8 on: July 15, 2017, 05:49:23 PM »
I've never given this much thought but makes sense. A shopping cart or my shell dollies for that matter have casters that swivel to allow positive caster to go in the direction I'm pushing.  My one dollie has a caster that sticks and it tries to turn in the wrong direction as the other casters. Till I give it a good kick and break it free.

Offline MPlayle

Re: Tow Bar help!
« Reply #9 on: July 15, 2017, 05:54:35 PM »
What is the angle of the tow bar?  Is it fairly level between the Mini and the tow vehicle or is there quite a bit of rise?  If a lot of rise, could it be enough to be "lifting" the front of the Mini?

Speculation:
Is it possible that if the front of the Mini is getting slightly lifted by the tow bar, then going into a turn will load the inside front wheel of the Mini while still lifting the outside which might be inducing body roll of a turn in the opposite direction?

NOTE: The above "speculation" is just that and may be totally off-base.

Where's the resident RV guru to chime in?


Offline 94touring

Re: Tow Bar help!
« Reply #10 on: July 15, 2017, 05:54:57 PM »
Apparantly there are a couple cars that have negative caster that drive just fine but can't be flat towed.  How much caster I don't know.

Online MiniDave

Re: Tow Bar help!
« Reply #11 on: July 15, 2017, 06:36:21 PM »
Angle was good, no issue there.....

I'm trying to get on the alignment machine again tomorrow to see if I screwed up and put negative instead of positive caster.

I got into the shop tomorrow, I'll let you know what I find.
« Last Edit: July 15, 2017, 07:19:17 PM by MiniDave »
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline jeff10049

Re: Tow Bar help!
« Reply #12 on: July 16, 2017, 12:31:43 AM »
generally a castor problem, but way towed out can also cause this.

Online MiniDave

Re: Tow Bar help!
« Reply #13 on: July 16, 2017, 12:01:19 PM »
Think I found the problem, thanks to all who commented! I haven't tried it yet behind a tow vehicle, but I feel much more confident now......I evened the numbers out before I finished.
« Last Edit: July 16, 2017, 12:57:37 PM by MiniDave »
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline 94touring

Re: Tow Bar help!
« Reply #14 on: July 16, 2017, 01:06:40 PM »
That must be before and after?  So it did have negative caster?

Online MiniDave

Re: Tow Bar help!
« Reply #15 on: July 16, 2017, 01:26:23 PM »
Yes, I was misunderstanding what the numbers were saying - I went from 3* neg to 3* pos caster. I haven't tried to tow it yet, but I may later this evening when it cools off a bit - really hot out right now!
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline MPlayle

Re: Tow Bar help!
« Reply #16 on: July 16, 2017, 01:50:23 PM »
Did you do anything at the rear?  Those numbers seem to have also changed slightly.


Online MiniDave

Re: Tow Bar help!
« Reply #17 on: July 16, 2017, 01:59:37 PM »
No, every time you move the car on and off the machine you get slightly different numbers.....I only changed the front end.
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Online MiniDave

Re: Tow Bar help!
« Reply #18 on: July 16, 2017, 03:10:58 PM »
Just had Rose tow me around the block in the '73 behind my Blue Clubby - towed perfectly.

Mystery solved. I knew it had to be something simple.......

Thanks again for all the comments from the brain trust....I was headed down the same path in my thinking but it was nice to have confirmation.
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Online BruceK

Re: Tow Bar help!
« Reply #19 on: July 16, 2017, 07:24:50 PM »
Good to hear the mystery is over.  I was pretty sure it was caster.
1988 Austin Mini
2002 MINI Cooper S
2007 Triumph Bonneville

Online MiniDave

Re: Tow Bar help!
« Reply #20 on: July 17, 2017, 07:52:46 PM »
The owner towed his '73 home tonight - about 25 miles - he said it worked like a charm, tailgated him all the way home!   ;D
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline Bahowe1

Re: Tow Bar help!
« Reply #21 on: July 18, 2017, 05:30:22 AM »
Interesting... I also was guessing caster, but I was second guessing myself because I thought if it were caster, it wouldn't tow properly at all.  The wheels would continuously try to swing behind the axis, not only in turns.  Further I doubted myself because I would have assumed the wheel would not snap back to center after a turn and it would be noticed in driving. 
Learned something.

Online MiniDave

Re: Tow Bar help!
« Reply #22 on: July 18, 2017, 06:32:45 AM »
I went down the same mental road - why didn't it drive funny? which it didn't.....

After I got it set correctly, I really didn't find any difference in the drive or cornering. But now it tows properly.....the owner was gobsmacked, and didn't believe it would work either but we went around the block, and then he towed it home and was very pleased with the results.....I guess that's what counts but I sure felt like a dumbass for not seeing that I had it wrong.

I also thought it would make a difference in where the wheel set in the wheel opening, but it wasn't noticeable......I went from 3 neg to 3 pos, I thought that was a hell of a lot of swing but I guess it's not so much - just enough to make it all work properly.

You learn you grow.

BTW, there are a number of cars that DO use neg caster - Mercedes is one - they use it to reduce steering effort.....and of course, they absolutely cannot be flat towed.
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline 94touring

Re: Tow Bar help!
« Reply #23 on: July 18, 2017, 07:24:55 AM »
When I was researching there seemed to be a variety of cars produced in the 50s with negative caster. 

Online BruceK

Re: Tow Bar help!
« Reply #24 on: July 18, 2017, 07:53:23 AM »
When I was researching there seemed to be a variety of cars produced in the 50s with negative caster.

So they could reverse the car with ease?  8.gif
1988 Austin Mini
2002 MINI Cooper S
2007 Triumph Bonneville