How is a Tow Bar supposed to work?

[doc]

Originally Posted by bamaboy473

What does an approval process entail, and who would supply such an approval?

Think about it, you're wanting a vehicle that has a frame that something can be attached to......they all have a frame, AFAIK.

You want a transmission that allows itself to turn with the engine OFF....some can and many can't, and some can be modified with external pumps. A BMW's 5-speed transmission is of the type that Can.

You want a steering wheel that free-wheels....they can all do that one way or another. This BMW just requires that the key be in the ignition.

So, after a lot of help from this forum, and after a lot of work and thinking about things, it can be said that I give my approval, pending a road test coming up in a couple of weeks

By approval, I mean North American BWM. For a boy with all the answers, I figure you would have figured that out. But then "bama" might also figure into the equation. You come here with a question and asking for comments and get offended from the comments. I am guessing Auburn area.
Certainly not an engineering school.
Why act like a smart A with answers? Several here have commented, suggesting things that might be helpful to you and you act like someone insulted you. Class act my friend, class act.

[Waiter21]

Find a couple pieces of 1 1/2 square tubing, maybe 3/16 wall. Weld these to the arms. weld the two finger tab that connect to the tow bar to the square tube. Make sure there is plenty of side gussets. TESTING : You should literally be able to drag your car sideways by the tabs. You should also be able to lift the car by the tabs.

As I've been following this thread, I pulled out the drawings for my Saturn Vue base plate. Demco did exactly what I would do.

NOTE - I know my limits, I would not weld anything that I deem human safety stuff. i,e hitches. Although I can burn stuff together with a small tig / mig welder, I don't trust my capabilities as a welder. Maybe I need to take a course instead of doing it the way us farmers do it...

[TonyDi]

THREAD WARNING

We take the “ be nice rule” very seriously. There have been several posts with rude comments. That needs to stop now. We don’t want to have to close this thread.

[JpalmerCass]

Originally Posted by Waiter21

NOTE - I know my limits, I would not weld anything that I deem human safety stuff. i,e hitches. Although I can burn stuff together with a small tig / mig welder, I don't trust my capabilities as a welder...

Well there you go, the really good welders, boilermakers and pipefitters who weld to ASME high pressure codes, don't say TIG, they say heli-arc. ;-)

[bamaboy473]

Originally Posted by doc

By approval, I mean North American BWM. For a boy with all the answers, I figure you would have figured that out. But then "bama" might also figure into the equation. You come here with a question and asking for comments and get offended from the comments. I am guessing Auburn area.
Certainly not an engineering school.
Why act like a smart A with answers? Several here have commented, suggesting things that might be helpful to you and you act like someone insulted you. Class act my friend, class act.

come on, Doc, don't go down that "condescending" road on this thread. You have offered nothing of substance, yet sought to impinge on certain aspects of area or location or schooling.

Not only am I'm from Alabama, but also from Florida, Texas, NY, and South America. It isn't about where we're from, it is about what we do with our interests.

To rebut your question, what could you imagine that it would take for you to ask BMWNA about installing a tow base plate? What would ANY manufacturer say to somebody wanting to do something that wasn't in the factory cook-books? Would they respond NO because it can't be done, or because it can't pass the legal department?

If YOU are from the corporate world, I can understand your need to not see things clearly...

I'm a smart azz to those that don't think progressively. So be it. All I want is to use the gifts that forum members have in order to solve a challenge. Thankfully, a lot of you have done just that, and my project is the better for it.

[bamaboy473]

Originally Posted by JpalmerCass

Well there you go, the really good welders, boilermakers and pipefitters who weld to ASME high pressure codes, don't say TIG, they say heli-arc. ;-)

The guys did the fabricating and welding work at two different shops. One is a body shop that specializes in restorations and airplane work. The other specializes in trailer building and repair. Neither is bad; neither is cheap; both are doing this seat of the pants as a project. If things needs changing, they go back to the shop for changing. I am not a welder, I am a paying customer.

If things fall apart on the road, it's on me, but safety for my wife and coach and pup are paramount. Those that even begin to suggest otherwise are...hmmm

[bamaboy473]

Thanks to all those that posted your comments, education, warnings and suggestions on this thread.

Going from whether to lock or unlock a steering wheel all the way through to installing braking and break-away systems has been a great education, and one that we'll take pleasure in testing within a few weeks when we make our next trip.

As it happens, I'm a jerk that doesn't like being pushed around because I respond in kind, [mod edit]

Thanks all, and wish we could have shared our commentary about the trip and how the set-up went. Better yet, wish that photos could have told the story, either good or bad.

Happy winter season. I very much appreciate what you did for Sandy and me.

[LakeTahoe]

A quick search found this.

"The ZF manual stipulates: Towing in a horizontal position is permissible. If the vehicle cannot be towed in a horizontal position, the front axle can be lifted to create a maximum of seven degrees (7*) of vehicle tilt. If these guidelines cannot be observed, then the driveshaft must be removed before towing, or damage to the transmission will result.

Maximum towing speed: 80 km/h (50 mph)
Maximum towing distance: 100 km approx. (62 mi approx.)"

I didn't read every thread here, but from the initial posts with pictures I could see this was an accident waiting to happen. I'm sure you love your BMW as I would, but your baseplate is unsafe and you'll likely ruin your trans because of lubrication problems. The ZF trans can likely be towed a very short distance for emergency situations but I believe that's it. If you think otherwise, then contact the transmission manufacturer and not BMW.

[aether_one]

Originally Posted by LakeTahoe

A quick search found this.

"The ZF manual stipulates: Towing in a horizontal position is permissible. If the vehicle cannot be towed in a horizontal position, the front axle can be lifted to create a maximum of seven degrees (7*) of vehicle tilt. If these guidelines cannot be observed, then the driveshaft must be removed before towing, or damage to the transmission will result.

Maximum towing speed: 80 km/h (50 mph)
Maximum towing distance: 100 km approx. (62 mi approx.)"

I didn't read every thread here, but from the initial posts with pictures I could see this was an accident waiting to happen. I'm sure you love your BMW as I would, but your baseplate is unsafe and you'll likely ruin your trans because of lubrication problems. The ZF trans can likely be towed a very short distance for emergency situations but I believe that's it. If you think otherwise, then contact the transmission manufacturer and not BMW.

Which ZF manual? You know there are multiple ZF transmissions including automatic transmissions which by the 1999 BWM 5281 Owners Manual can be towed:

Towing a vehicle with automatic transmission
1 Place the selector lever in position N
2 Towing speed:Max. 45 mph (70 km/h)
3 Towing distance:Max. 95 miles (150 km)
4 Leave the ignition key at position 1 to ensure that the brake lamps, turn signals, horn and windshield wipers remain operative, and to prevent the steering lock detent from engaging

No mention of towing a manual transmission.

[MCR]

The base plate needs to be made so it cannot not bend in either direction . 1/2 inch welded steel with gussets on either side for sure . How long is your base plate from connection at the car frame? You may need an external
Bar that connects the two base plates together .
I made base plates for my jeep and they are maybe 3 inches long and bolted the the heavy duty bumper.
The steel bumper is rigid enough so no external bar needed.
FYI when hooking up either a blue ox or Roadmaster tow
Bar you want have the tow bar fairly level . This will reduce any
Unwanted force on the base plates. it will avoid
The car front end from dipping down or jumping up
If you need to brake suddenly !
Also when your all hooked up and ready to roll you want to be on a reasonably flat solid surface to engage or lock in the tow bars.
The tow car needs to be in neutral and the steering lock disabled .
Once you start moving the RV forward the tow vehicle front wheels may drag a little at first as you move slowly and will spin the car steering wheel untill you straighten
Out . Always a good routine to stop and check a second
Time before heading out 👍🏻 Cheers.

[Wayne Clamp]

Not intended to be smart ass remark but, with that said, suggest you increases your liability insurance to a couple of million and maybe a self retainer deductible of , say, 50,000 and a couple of million dollar blanket. Otherwise just by the proper base plate and braking system. Also, notify folks which roads you will be traveling so we can choose others. Seriously your creating an immense liability exposure for yourself and whom ever is building that fiasco for you

[Kountry_star]

Being somewhat of a do it yourself / don't confuse me with the facts person I can understand your wanting to do it "your way". To help your way out, I might suggest you go to a site that produces the brackets and look at the various ways they use to safely attach safety chains / cables and ways to attach side to side support. Roadmaster (and I'm sure all the others) has a very good site that also includes installation procedures. Could save a lot of "re" design changes and help produce a safe and reliable final product. If your Manual trans can't be towed (long distances) as I believe is the case with yours (limited to 100+ miles) there are companies that make recirc pumps that will circulate the trans oil so your trans won't be damaged. I believe Demco is one. Happy trails and let us know how it all works out.

[BD104X]

I’m gonna throw my hat in the ring!
I’m with the OP that something can be homemade can still be safe but I’m of the opinion that you need to basically make it twice as strong as you think it needs to be as a starting point. I have no formal engineering degree but have built lots of my own stuff and have towed a 32’ trailer with a motorhome for more miles in a year than many will ever drive in a decade. My two observations:
Your safety chains / cables need to go to a separate mounting point all together or it defeats the purpose in the event that the original mounting point fails.
Your Sequoia test vehicle has way less overhang after the rear axle, so the increased “swing” of making a turn with your motorhome will exaggerate the forces placed on your tow setup and you shouldn’t underestimate that.
.
Kudos to you on trying to do this but in my honest-but-unqualified opinion it all needs to be “beefed up”.
Good luck, carry on!

[carlgorski]

Originally Posted by bamaboy473

I inherited a Blue Ox tow bar when I bought the coach, and have recently completed fabricating a base plate, and installing an Invisibrake system, so ready for the road test! hmmm, not good.

The right base plate tab bent down about 60 degrees. I straightened it out and tried it again, but the tab bent with the car being towed out of the driveway (right hand turn). Here is what I noticed:

The arms on the tow bar lock in the extended position and stay that way. Is this the way they're supposed to be?

The hitch height is 16" and the tow eyes are 11" high. I thought I read that a 6" difference was acceptable, but is this correct?




Any other causes of high stress while turning?

just by a baseplate