OEM Trailer Hitch

[TerminatorX5]

Originally Posted by xsx450

It is bolted to the subframe of the x5 There is an extremely heavy duty box frame that runs right behind the rear differential which you drill a hole into and then use a special bolt which expands when you torque it the first time like a pop rivet and then you retorque it with a 1/2" Bolt.

Any downward force would be transfered very evenly with the mount. I believe the shear strength of the bolts does matter, unless you think the rear frame is going to rip off?

sounds like a "Jesus" bolt... Interesting, a frame that is behind rear diff... i wonder, what the purpose of it there... i need to pull out some of the blueprints, see what it does...

[JCL]

Originally Posted by xsx450

I get what you guys are saying, but you are just SAYING. I am doing. They are not bolted to sheet metal, or the floor pan. This is not one of those mounts that screws through your spare tire floor in the trunk.

It appears that the Reese cross bar bolts on to item 14, in the parts book drawing attached. That is a lateral tie piece that holds the two axle supports (2 and 3) from spreading apart. It is not strong in the fore/aft directions, unless you through-bolt to item 1 (not sure if your hitch does that, or not, as some do). It shows as being braced to item 1 in any case. Item 1 is the trunk floor. Item 14 is braced to the trunk floor because it isn't very strong by itself, it is very thin. It is the piece that BMW discards in their OE hitch installation. So, it appears that despite your claim, this is one of those mounts that is attached, either directly or indirectly, to the spare tire floor in the trunk.

All of our equations mean jack because for one they aren't accurate, and two I have loaded up over 900 lbs on this thing over 24" out of the hitch, jumping up and down. No stress fractures, no tearing subframe. Nothing.

This equation is totally accurate. The math is pretty simple. The design load is published as 600 lbs vertical at 8", if you use the reinforced OE hitch. You have applied 1.5 times the rated load, at 3 times the rated distance. That is 4.5 times the design load. Glad that worked out for you. Some of us just believe that some calculations do mean something. You don't have to agree, you are certainly entitled to your own opinion. You are saying that because it hasn't broken yet, it is strong enough to last forever, that fatigue isn't a factor. OK.

As an aside, the strength of the front bolt doesn't matter. It is strictly a locating point. All the force from the hitch stabilizer bar at that end is upwards, not downwards, so the bolt doesn't see any significant stress.

The failures that we did see back in the early days of the X5 were in fact to the rear pan, item 1. Yes, it was ripped off. Repairs were expensive. That was why the aftermarket hitch manufacturers added that longitudinal brace. They also include a line in their hitch warranty that states that they do not guarantee that the hitch is fit for use. Their 6000 lb rating is likely based on bench tests of their hitch in a jig, not on having it mounted on a vehicle. We all accept that it has a 6000 lb rating, just not that their way of rating the hitch has any relevance.

[upallnight]

Here's a youtube video on how to install the reese or similar hitch.

Trailer Hitch Installation - 2001 BMW X5 - etrailer.com - YouTube

[TerminatorX5]

Originally Posted by xsx450

All of our equations mean jack shit because for one they aren't accurate, and two I have loaded up over 900 lbs on this thing over 24" out of the hitch, jumping up and down. No stress fractures, no tearing subframe. Nothing
You guys on these forms make me laugh sometime (like right now). I think some among us need to spend money on anti anxiety medicine not throwing money down the drain to ease their conscious....

As I mentioned before, this is your car, and you can do anything to it - my opinion would matter ONLY, when you are selling your car and I am buying it... other than that - my opinion is just that - an opinion...

However, my opinion about your opinion about the math and physics is that your opinion rather incorrect - the force of gravity is still the same, regardless if you are in the US or in North Korea, or 30 miles up in the space... same goes for 2+2 - it is always 4, no matter what propaganda might be telling you.

Of course, you are entitled to the opinion that the gravity does not matter and 2+2=7... This is totally free country and thank God, we are not in North Korea or the Soviet Evil Empire, where they would have beaten the "4" into you against your will... So, it is very much possible, that your opinion about the equations is totally right...

I am totally with you, dude - the collective opinion of the old farts that owned the stupid car for long time and saw things, matters not... Carry on... we will be here when you have questions...
Let me pop some corn...

[upallnight]

Originally Posted by xsx450

.............You guys on these forms make me laugh sometime (like right now). I think some among us need to spend money on anti anxiety medicine not throwing money down the drain to ease their conscious....

Thanks for reminding me, I need to take my Meds.

[xsx450]

The center support bolts through the Rear Axel Carrier.

Im going to go have fun in my x5 and on my dirtbike and not worry about a damn thing!

The the $350 I Saved on my hitch I; went dirtbiking 5 times, took my girlfriend to dinner and a movie, got laid, filled up my tank a few times and bought a few shots for my buddies at the bar. Life is short...

[TerminatorX5]

Originally Posted by xsx450

The center support bolts through the Rear Axel Carrier.

Im going to go have fun in my x5 and on my dirtbike and not worry about a damn thing!

The the $350 I Saved on my hitch I; went dirtbiking 5 times, took my girlfriend to dinner and a movie, got laid, filled up my tank a few times and bought a few shots for my buddies at the bar. Life is short...

isn't rear axle... er.. axel, a dynamic part, that is part of suspension, and as such is flexible in relation to the rest of...

wait... saved $350? well, then, it is a different story...

what part of the world are you at, that $350 lets you fill up your tank a few times? my single fill up (premium) is about $80...

dude, either you live in Venezuela, or Saudi Arabia, where gas is dirt cheap, or I really need to learn how to stretch the $$$ to get myself gas, dinner and a movie, get laid... oh, and buy my friends few shots... i hope you had a shot or two as well (unless you are not of legal drinking age, then never mind the drinks)...

I seriously need to re-evaluate my spending habits!!!

[Porschesolutions]

There were plenty of warnings against not using non-OEM hitches, + plenty to support to account for the extra $.

Since I tow my boat or race car trailer, I wanted a stout hitch I wouldn't ever worry about. If I were merely towing a motorcycle trailer or small utility trailer, I prob. would have gone with a lighter duty trailer.

[xsx450]

Originally Posted by TerminatorX5

isn't rear axle... er.. axel, a dynamic part, that is part of suspension, and as such is flexible in relation to the rest of...

wait... saved $350? well, then, it is a different story...

what part of the world are you at, that $350 lets you fill up your tank a few times? my single fill up (premium) is about $80...

dude, either you live in Venezuela, or Saudi Arabia, where gas is dirt cheap, or I really need to learn how to stretch the $$$ to get myself gas, dinner and a movie, get laid... oh, and buy my friends few shots... i hope you had a shot or two as well (unless you are not of legal drinking age, then never mind the drinks)...

I seriously need to re-evaluate my spending habits!!!

Originally Posted by Porschesolutions

There were plenty of warnings against not using non-OEM hitches, + plenty to support to account for the extra $.

Since I tow my boat or race car trailer, I wanted a stout hitch I wouldn't ever worry about. If I were merely towing a motorcycle trailer or small utility trailer, I prob. would have gone with a lighter duty trailer.

Well there you go. A practical application and need.

[davintosh]

Originally Posted by TerminatorX5

isn't rear axle... er.. axel, a dynamic part, that is part of suspension, and as such is flexible in relation to the rest of...

DING! DING! DING! WE HAVE A WINNAH!

The first thing that hit me was that the angled piece on the cheap hitch attaches to the subframe; that subframe is designed as a semi-free floating piece of the suspension. The rest of that hitch ties to the existing bumper frame. With the vehicle at rest, it doesn't make any difference, but I would imagine it would transfer some road noise to the frame (minor annoyance) but if you were driving it down a rough road, there would be a lot of torsion being placed on that bar, and torque applied to a now-weakened subframe (because of the hole drilled in it) and bumper frame. I don't think I'd be using that hitch, but if you're ok with it... It's your car, and your 600 lb motorcycle hanging off the rear end.

Dave (who, after seeing the ~$500 price tag at ECS Tuning is pleased as punch to have bought an X5 that already had the factory hitch on it. )