Flat towing a 1983 300SD behind an RV - PeachParts Mercedes-Benz Forum

tomas_maly · #1 05-14-2013, 07:46 AM

I am looking to find a way to long-distance tow my 300SD behind my RV (a school bus conversion) - and I think I'd like to flat tow it using a tow bar. The driveshaft will be disconnected (I can do this manually) so I'm not concerned about the transmission. I'm trying to work on the cheap (all my money is going toward the bus-motorhome to make it livable).

This is for long-distance travel so it needs to be safe and reliable.

Tow dollies don't seem to make much sense because you have to disconnect the driveshaft anyway. And towing the car backwards (front wheels on the ground) isn't stable above 25mph. A flatbed trailer is nowhere in my price range, not even used.

I just purchased an adjustable tow bar from Harbor Freight:

Tow Bar - Adjustable Tow Bar w/ 5000 Lb. Capacity

This does not have any mounting bracket assembly, and since the 300SD does not have a flat steel bumper (like jeeps) I would assume I need to mount it to the frame behind the bumper.

The kit comes with two small brackets for mounting onto a flat bumper, but it also advises to get a separate mounting kit (essentially two L-shaped bars sticking through the bumper) for MOST vehicles.

I've taken a look and it seems that for a permanent solution my best bet is to perhaps cut holes through the bumper on both sides and add some sort of mounting bracket assembly there. You can see what I mean if you download the user manual for this tow bar.

I have access to either 3/16" or 1/4" plating, which I can perhaps mount between the frame and bumper and/or drill several holes with large bolts to secure it to the frame.

The question then is, are there mounting brackets (the type that stick out beyond the bumper) that go between the plate and the tow bar (and where do I get them)? And if so, am I probably going to need to cut through my bumper?

tomas_maly · #2 05-14-2013, 07:56 AM

I'm assuming what I need are "tow arms", ie something like:

Or do the ends of the tow bar simply mount directly through the bumper, to the plate? I'm somewhat assuming this makes the tow bar too short and there needs to be pieces sticking out to mount to. Perhaps the lower halves of these tow arms here.

Alastair · #3 05-14-2013, 07:56 AM

I think you would need to check the legality of towing a heavy car like the SD behind a converted school-bus!
--All the states you intend to travel may have different rules about this.....

It certainly Wouldnt be allowed here in UK!--vehicle (trailer) weight limited to 750Kg I believe here for that sort of thing.....

What are you going to do for braking on what is now in effect a trailer?

tomas_maly · #4 05-14-2013, 08:05 AM

Or maybe I should return this Harbor Freight thing and get something brand name that also includes some sort of mounting bracket.

kerry · #5 05-14-2013, 08:34 AM

I used a folding towbar from Roadmaster on my Suzuki. Roadmaster sells mounting brackets designed for each specific vehicle. Not sure if they sell them for a 126. You'd have to check their website. I bought the towbar used. It will be a headache disconnecting the driveshaft everytime you want to tow it. Disconnect kits are available. They are not cheap. I decided it was cheaper and easier to tow a 4wd vehicle with a transfer case which permitted towing in neutral than to put a driveshaft disconnect on my 123 wagon. Nothing illegal about flat towing a car in the USA to my knowledge. I didn't use brakes on the Suzuki. I had a retarder on my Wanderlodge and the bus weighed 35k lbs. I didn't notice the Suzuki back there.

t walgamuth · #6 05-14-2013, 08:40 AM

I have a tow bar similar to the one pictured. I remove the bumper on a 123 car and bolt adapters onto the stub frame. The stub frame though is not all that strong since it is designed to collapse in a collision.

For a repetitive towing situation behind a motor home I would choose a trailer to put the car on. It can be backed which you cannot do with a tow bar and it has brakes which you won't have with the tow bar. The trailer will cost more, to
be sure but you will have it for any other purpose you might choose and when finished with it you can sell it and get most of your money back.

For me the main advantage with the tow bar is I can drive across the country to pick up a car with no penalty in fuel economy from towing a large trailer
and flat tow home with minimal sacrifice in fuel economy towing behind my 3/4 ton dodge truck.

GregMN · #7 05-14-2013, 10:05 AM

I mounted the tow bar to the bumper. Look at the 3rd photo on the first post : Towing an SEC with and SDL

The mounting hardware on the hitch you got will work. I would just make a larger backing plate for the bolts. I used a bumper from a parts car that I removed the cover and cut shorter to make it easier to transport from home to the car. If you don't mind some holes in the cover, you could permanently mount the hardware to the bumper by cutting out the bumper cover so they mount hard against the inner bumper.

ROLLGUY · #8 05-14-2013, 10:32 AM

Quote:

Originally Posted by GregMN

I mounted the tow bar to the bumper. Look at the 3rd photo on the first post : Towing an SEC with and SDL

The mounting hardware on the hitch you got will work. I would just make a larger backing plate for the bolts. I used a bumper from a parts car that I removed the cover and cut shorter to make it easier to transport from home to the car. If you don't mind some holes in the cover, you could permanently mount the hardware to the bumper by cutting out the bumper cover so they mount hard against the inner bumper.

Using a bumper from a parts car is a great idea. However, if you want something a little more permanent (and better looking), you need a "base plate" (something like the tow arms you pictured) that is mounted permanently under the stock bumper with only holes where the tow bar arms stick into. I had a base plate (made by Roadmaster) on my PT Cruiser that worked great. The arms were slotted in such a way that they were put into the sleeves (1 1/2 tube on each side) of the base plate, and turned in towards the center. The tow bar was then connected on the arms with quick disconnect brackets (another Roadmaster item). The best part of this system, is there is only a 1 1/2 tube sticking (about an inch) out from the bumper on each side. The rest of the mounting structure is under the bumper and cover. I still have the base plate and arms (crashed the car years ago), so I could probably get a photo for you if you would like. Come to think of it, these could be fabricated and modified to work on any vehicle (including an MB 126).

SD Blue · #9 05-14-2013, 10:56 AM

Personally, I wouldn't even consider flat towing a unibody vehicle with a tow bar. In a critical situation, (Think an emergency stop on a winding mountain road.) you don't have enough structure to maintain safe control. I know a tow dolly "sounds" redundant, it really isn't due to the frame of the dolly. Also, it would prevent a lot of strain on the steering system. Think twice about having to crawl under the car every time you want to go somewhere. (This will occur on a regular basis while rain is falling.)

The reason Jeeps and Samari are popular for flat towing is due to their frame for connecting a tow bar and the manual transmission.

If you go with the Mercedes, get a tow dolly with brakes. Northern Tool has brake systems you can add to a tow dolly. It is going to cost you more but the difference in safety is well worth it. Believe me, I towed a fifth wheel trailer for years and you will be thankful for the extra safety when a tire decides to separate at 70 mph! I've been there. Remember, we are not talking about just driving from point A to B, we are talking about towing on a regular basis.

compu_85 · #10 05-14-2013, 11:16 AM

If you bolt the towbar to the front bumper attachments it should be strong enough... after all that's what the factory hitches bolt to as well and we know those are strong! The bumper mounts are the strongest part of the car.

But, a dolly with brakes would be nice too. Honestly though... a tow dolly, with brakes, dragging a front wheel drive car around is probably the best bet. Having to diddle with the driveshaft sounds like a huge bother.

-J

t walgamuth · #11 05-14-2013, 11:58 AM

The bumper mounts are not that strong. I have pulled out bolts from them. They are designed to crush in an accident, not to attach tow bars to.

They're fine for occasional towing but not in my opinion for repeated towing. A trailer remains your best option for safety and convenience, though it does take space once you arrive at your destination.

ROLLGUY · #12 05-14-2013, 12:35 PM

Lots of opinions expressed here, but the OP will do what seems best for him based on those opinions (That is what I would do). My opinion is that the front bumper mounting points can be made strong enough to lift the entire car said said mounts if need be. I just had a look under my friends 126 a few minutes ago, and I see no reason why a mount could not be made so that the brackets stick out just below the bumper in the vented part (fascia). It would look much better than having holes drilled in the actual bumper. Again, just my opinion as to how I would do it if I had the need....Rich

t walgamuth · #13 05-14-2013, 01:06 PM

Attaching to the bumper is totally inadvisable. The bumpers fall off on their own due to corrosion.

Simpler=Better · #14 05-14-2013, 01:11 PM

Yeah I'm an idiot, see below:

charmalu · #15 05-14-2013, 02:48 PM

The only MB we hauled is a 78 240D and it was on a trailer. A Trailer is a much safer way to transport a large vehicle. although I have seen a lot of vehicles towed on a Dolly.

Towing with the rear end on the dolly is more of a safety issue with the majority of the weight now at the far rear. it would be like improper loading a trailer with the majority of the weight to the rear. it will cause a whipping action, then it can upset the towing vehicle and cause a major accident.

Each way to move a vehicle has it`s own set of safety issues to be aware of.

The OP has to weigh out what is best for him to work through, which every way is settled on, just do it safely.

Reading through this thread got me to thinking of this thread.

Towing DISASTER!!!

Charlie