Downforce rating of OE trailer hitch on E53

TerminatorX5 · #1 03-04-2013, 10:12 AM

I could not do a search here, for some reason it did not go through, so i am asking in a new thread...

i have a factory trailer hitch installed on the 2006 4.8iS.

I know this thing is rated at 6000 lbs but I am not going to tow anything at this time - I am thinking about getting a basket that attaches to the hitch and wanted to know, what is the weight limit on the downforce on those hitches...

I have a factory bike carrier that is attaching to the same hitch and the whole thing is heavy even without bikes, so I know, it can take some weight - I am just not sure about how much it can take...

Thanks...

Shang · #2 03-04-2013, 12:13 PM

Tongue weight on the e53 is 600lbs.

TerminatorX5 · #3 03-04-2013, 12:36 PM

Quote:

Originally Posted by Shang

Tongue weight on the e53 is 600lbs.

thank you

JCL · #4 03-04-2013, 05:52 PM

Incomplete answer.

Tongue weight is specified as 600 lbs, on smooth roads, for a load applied no more than 8" horizontally from the receiver pin to the ball. BMW tech documents provide a drawing for that. I have posted it here before. There is also a maximum vertical drop. It is clear that there is a bending moment limitation, from that specification.

So, if you apply the load at 24" (pin to CoG of the load) then you have a 200 lb capacity.

Also, the smooth road limit is because of bouncing. If you have a bouncing load, often related to off road use, the 600 lbs goes down considerably, to 330 lbs. A bouncing load at 24" CoG would have a 110 lb load limit (including the carrier). Hitch balls don't tend to bounce so much, because they apply the load close in to the support point.

This is all important due to the number of carriers that result in bent hitches. People think 600 lbs, think they can apply that load at any location, go over bumps that cause the load to bounce, and are then surprised that their 6000 lb hitch failed.

TerminatorX5 · #5 03-04-2013, 06:05 PM

100lbs with the weight of the basket is more than enough - it will just a suitcase with cloth that can't make it in the cargo area... that's all...

Shang · #6 03-05-2013, 12:35 AM

Lol! Yeah, you won't have any problems. You would have to haul eight late 90's downhill bikes on a hitch mounted carrier before you would need to worry. I haul a 240lb dirt bike and a 5 gal fuel jug on a hitch carrier with no problems. My old jeep hauled the same with no problems with a lower tongue rating. (Though with much less style and comfort than the X5...)

JCL · #7 03-05-2013, 01:06 AM

Big difference between a Jeep with a frame and a unibody X5.

Shang · #8 03-05-2013, 01:33 AM

My jeep was a Cherokee. Unibody. I'm not arguing with you, you are right. They make a dual dirtbike carrier that I would never consider putting on a 600lb tongue for the very reasons you stated. Even though without considering things like bounce and distance from the receiver, the stated rating implies it shouldn't be a problem. I just know that nobody is going to have a problem on an X5 with a bicycle rack or a cargo carrier.

JCL · #9 03-05-2013, 01:48 AM

I have seen pictures and read the service reports of a 2001 X5 that had a cargo carrier in an X5 hitch, and ripped the rear pan off. It went on for months as the owner negotiated with BMW. As I recall, it was $12k + in repairs, and that was years ago. Other reports are on here from dealer techs who have sealed up the seams in the trunk floor on multiple vehicles when they ripped open from the same loading.

So I guess I would be cautious about cargo carriers, especially when BMW go to great lengths to limit the permitted bending moment.

I agree that 100 lbs plus 50 lbs for a carrier, pulled in close, won't be a problem.