E36 vs E46

[Z3_GoCar]

I think no one here would have an issue with you following these instructions for your E46. The rulebook says:

"All chassis/structural/electrical repair, if performed, shall be in concurrence with factory procedures, specifications, and dimensions. Unless specifically authorized by the manufacturer for repair or allowed by these rules, no reinforcement, i.e., seam welding, material addition, etc., is permitted."

Such a procedure, on your car, would be in concurrence with factory procedures, and would be specifically authorized by the manufacturer for repair. As long as your car was built before 2/00, I guess, since that's the limit of applicability of this bulletin.

But doing a similar thing on an E36, or reinforcing the trunk floor of a Z3 because they tear apart at the diff mount, wouldn't be legal without such a document.

BMW might not want these documents to circulate to the owner population, but as you know, most racers don't have "legitimate access" to them, and yet, the racing rules require us to have them in our possession. So, we're good at looking for them.

Josh, you've followed the Z3 trunk mount repair threads. Have you ever found any evidence that BMW even documents this much less has internal memo's for dealer service personel to access? I've long ago come to the conclusion that it either doesn't exist or is so closely held it might as well not exist. Unlike my employer, you can't file under the freedom of information act and get these kinds of proprietary reports. I'm sure it'd be easier to get Air Force reports on the fatigue life on an F-15 airframe than how the factory wants these repairs made.

I had the rear bracket to the muffler break off of my (street) Z3. That's like four spot welds can't hold the stock muffler for more than 89k miles? There's maybe double that many spot welds in the trunk holding the bracket for the off set differential mount. This is all that holds the differential from pulling away from the trunk. When it goes one would have to be really lucky not to wrap it into a pretzal, and just becaue there's not manual or paper trail we've got to throw it away, or go race E-Production:eek:

James

[JoshS]

Josh, you've followed the Z3 trunk mount repair threads. Have you ever found any evidence that BMW even documents this much less has internal memo's for dealer service personel to access? I've long ago come to the conclusion that it either doesn't exist or is so closely held it might as well not exist.

I agree. And I think the same is true for any E36 repair documents.

All we can do is repair to original specs. That means we can buy brand new sheet metal, and spot weld it in the same way as the originals. The good news is that those trunk floor panels are still available ... no need for a body-in-white should it happen. It's definitely a more extensive (and expensive!) repair than a broken 944 control arm would be, but should it happen, it won't be the end of the world.

BTW, Rob, I'm sure the same is true for the E46 ... even if that bulletin didn't exist, replacement original body parts (vs. smaller reinforcements) could be purchased and welded in.

[robits325is]

We did have the front sway bar mount tear and we were able to buy the original replacement mount from BMW and spot weld it back in place. That type of repair is easy and returns the car to factory spec.

In the case of the E-36 subframe the cost to replace the floor pan would exceed the cost of some IT cars in their entirety.

Have you had to repair the rear sway bar mounts on your Z3 yet? If so, did you drop the subframe and replace the entire trailing arm or just weld the thin tab back on? If not, what will happen when they fail?.

With reguard to posting internal BMW documentation, I would be weary. The link I supplied was posted by someone else on Bimmerforums. Have you ever read the disclaimer when you log on to the BMW site? Scary stuff. Tightly held is an understatement.

[dj10]

We did have the front sway bar mount tear and we were able to buy the original replacement mount from BMW and spot weld it back in place. That type of repair is easy and returns the car to factory spec.

In the case of the E-36 subframe the cost to replace the floor pan would exceed the cost of some IT cars in their entirety.

Have you had to repair the rear sway bar mounts on your Z3 yet? If so, did you drop the subframe and replace the entire trailing arm or just weld the thin tab back on? If not, what will happen when they fail?.

With reguard to posting internal BMW documentation, I would be weary. The link I supplied was posted by someone else on Bimmerforums. Have you ever read the disclaimer when you log on to the BMW site? Scary stuff. Tightly held is an understatement.

I'm no attorney but wouldn't this be covered under the "Freedom and Information Act"?

[Greg Amy]

...wouldn't this be covered under the "Freedom and Information Act"?

No. FoI (Freedom of Information Act) applies to records held by various Federal government agencies, not to private/public corporations. BMW is fully within its rights to withhold this information as proprietary.

To the issue at hand:

Those documents that Josh linked to are fine example of what exactly one needs to support other-than-returning-to-factory specs mods/repairs. As a tech inspector and a competitor, I would accept those as reasonable proof of appropriate and legal repairs. As long as Rob's car is manufactured within the dates specified in that bulletin, he's golden to do this work. And, frankly, I'm OK with him doing in in advance as a "prepair"; after all, how can one prove that the parts were installed as a repair or not? The mod - as detailed in that "TSB" - is legal, regardless of when or why it was installed.

However, absent such a TSB, this repair is never legal. And, the TSB above does not cover the secondary outstanding issue at hand (and prior), that being the rear subframe tears on the E36, and E46s subsequent to 02/00.

Further, regardless of whether BMW is tight-lipped about this repair or not, the responsibility is on THE COMPETITOR to prove it's legal. If you get protested for such a repair, stating that "it's legal but BMW won't give me a copy of the bulletin" is wholly insufficient as supporting evidence. You WILL be found to be contrary to the regulations absent this proof.

I think Josh summarized the situation quite well:

- "All chassis/structural/electrical repair...shall be in concurrence with factory procedures, specifications, and dimensions..."
- Such a procedure, on your [E46] car [built before 02/00, inclusive] would be in concurrence with factory procedures...
- But doing a similar thing on an E36, or reinforcing the trunk floor of a Z3 because they tear apart at the diff mount, wouldn't be legal without such a document.

Can anyone offer a better way to fix a torn subframe or a ripped out shock mount?

To the rules. Consult your workshop manual and technical service bulletins.

I can"t remember a weekend that Smarty wasnt under someones car welding for a case of Pabst.

True, and those repairs could very well be illegal. And, in fact, I've mentioned that to Bob a couple of times, making sure he understands he should do the minimum required to "repair" and not "reinforce."

But prevalence of a modification does not equate legality.

In the case of the E-36 subframe the cost to replace the floor pan would exceed the cost of some IT cars in their entirety.

That's unfortunate, but that's the rules. If you don't agree with them, work towards getting them changed. Maybe you can talk the CRB into a spec line allowance for such a repair kit? If your car is not included in the above TSB you could include it as supporting evidence of a significant problem with the car, and you might get an allowance.

As we've noted many, many, many times before on this board, you pick your cars ("warts and all" is what we say). Yes, it sucks to have to repair the chassis of your BMW annually (or more frequently), but it also sucks to have to replace your Rabbit front hubs every three races, and your 944 control arms every few races, and your Saturn and NX2000 rear wheel bearings every few races. Sure, those examples do tend to pale in comparison to what BMW drivers are facing, but the modifications you're suggesting to "fix" your issue(s) are no less illegal than installing Audi hubs, cast aluminum control arms, or illegal alternate replacement bearings, respectively.

Warts. We all got 'em, just in various levels...

GA

[lateapex911]

Further, I suspect that replacing the entire fllor of the car is overly invasive, and that there are more expedient methods.

Rob, I remember you posted pics and captions of the underchassis repair/welding on your E36. So, what you're saying (I'm getting confused with E36s, E46s and Z3s) is that you have the documentation for that procedure, but won't let anyone see it for fear of legal repercussions from BMW?

[JoshS]

Have you had to repair the rear sway bar mounts on your Z3 yet? If so, did you drop the subframe and replace the entire trailing arm or just weld the thin tab back on? If not, what will happen when they fail?

I don't use a rear swaybar, partially for this reason. The swaybar mounts won't break, and it's also less load on the trunk floor, so maybe it'll last longer. If one can get the setup to work without this risk, it's altogether better.

But if I were and the mounts were to break, I'd have just welded the thin tab back on to the trailing arm.

[GKR_17]

I don't use a rear swaybar, partially for this reason. The swaybar mounts won't break, and it's also less load on the trunk floor, so maybe it'll last longer. If one can get the setup to work without this risk, it's altogether better.

But if I were and the mounts were to break, I'd have just welded the thin tab back on to the trailing arm.

You don't have to use the stock swaybar mounts. Weld in better ones somewhere else.

[JoshS]

You don't have to use the stock swaybar mounts. Weld in better ones somewhere else.

Good point. In my case it's more about the fear of flexing the trunk floor to pieces than it is about the failure of the mounts themselves.

[Z3_GoCar]

It's not just the chassis mount that needs to be stonger, the metal tab on the trailing-arm has been know to break. John Huestis rolled his M-roady at Thunderhill turn 3 because the mount broke on the trailing arm. I think I'm going to weld a new thicker tab on my new arms before I install them. Also, the box the bumper mounts to would make an ideal place to mount the rear bar to.

James