DIY - Chassis reinforcement ideas

One thing I notice when driving the car hard on tight twisted roads is that the chassis flexes. As I’m about to get my car repainted I was wondering what people have found to be the most useful for chassis strengthening. I know Coupeking is doing that almost as standard procedure. A lot of the work seems to be around adding welds to things like the rear wheel well to the bulkhead behind the rear seats. I’ve also seen a triangle shape being added in the engine bay between the frame rail and the firewall.

Does anyone have any experience to share in that area?
 
Last edited:
Click to expand...
I am a horse that needs to be led to the water. There must be pics out there of these welded in strategies that some have done? I will surely share what I do when I get to that point. There should be nothing proprietary about strengthening/improving our cars within this community. We're not racing against one another. ;)
 
autokunst said:
I am a horse that needs to be led to the water. There must be pics out there of these welded in strategies that some have done? I will surely share what I do when I get to that point. There should be nothing proprietary about strengthening/improving our cars within this community. We're not racing against one another. ;)
Click to expand...

Yeah, but I can see Coupe King's side of this too. He's in the business of restoring these cars, and if he publishes all of his knowledge, then people don't need to come to him.

Further to my earlier comment, I suspect that is why there are no pictures of Mario Langston's modification to Tom Samuelson's car.
 
Ohmess said:
Yeah, but I can see Coupe King's side of this too. He's in the business of restoring these cars, and if he publishes all of his knowledge, then people don't need to come to him.

Further to my earlier comment, I suspect that is why there are no pictures of Mario Langston's modification to Tom Samuelson's car.
Click to expand...
I hear your point. But I still think that the concept is different than the quality. What you "buy" from CK or VSR is the service of them doing the work, and the quality that they offer in their work. I don't think they (or anyone) should withhold what they're doing. In fact, it may drive more business their way if they can demonstrate their quality and attention to detail. A do-it-yourselfer isn't going to bring a car to them anyway. But folks that are going to choose to pay to have the work done will see those shops as a better option than another.

An example is when I had my M3 lowered and stiffened. The shop welded in several supports at the suspension points to reduce/eliminate cracks and tearing to the car chassis. This wasn't proprietary, it was just what they (and any other competent shops) should do when stiffening the suspension of an M3. I chose to have their shop do the work because they took these appropriate steps to better the outcome.

Sorry to sound so combative. I just can't believe that some photos of what others have done are so top secret. :cool:
 
Ohmess said:
Further to my earlier comment, I suspect that is why there are no pictures of Mario Langston's modification to Tom Samuelson's car.
Click to expand...
By the way, I absolutely appreciate that if something was done on commission for a unique client project/request, that it would likely not be published openly.

Not sure why I feel so worked up about this. I am usually about as anti-open source as they come. But given I am knee deep in my own chassis work, I have skin in this game. ;)
 
It would be nice for those that come here looking for parts for their paying customers/business would offer up some of their expertise instead of it always being one-sided.
 
Ohmess said:
Yeah, but I can see Coupe King's side of this too. He's in the business of restoring these cars, and if he publishes all of his knowledge, then people don't need to come to him.

Further to my earlier comment, I suspect that is why there are no pictures of Mario Langsten's modification to Tom Samuelson's car.
Click to expand...
LOL, that's too funny Chris .. .
I will add that we have found several e9 CS coupes with spot weld locations that were missed at the factory. These were all at the bottom of the A pillar on the right side. To stiffen this chassis adding additional welds and or seam welding the entire rocker panel structure all the way back to the rear seat partition and adding to the welds between the A pillar and the strut tower will substantially change the way the car feels and drives.
 
Having a roommate & colleague doing stress fatigue testing on Volvo cars around 2010, I know that some spotwelds simply fail over lifetime due to repeated flexing.
We had a rig in our facility that took the car by its 4 wheels on hydraulic 6 axis pistons and simulated 200.000 km driving back country roads (~ 120.000 miles) in 6 weeks. A few percent of the spot welds would simply fail.
Notorious were the welds around factory installed trailer hitch; but then perhaps people don't drive them for 200.000 km over back country roads fully loaded....

Plug (rosette) welds are much stronger.
 
Last edited:
Mario L. said:
LOL, that's too funny Chris .. .
I will add that we have found several e9 CS coupes with spot weld locations that were missed at the factory. These were all at the bottom of the A pillar on the right side. To stiffen this chassis adding additional welds and or seam welding the entire rocker panel structure all the way back to the rear seat partition and adding to the welds between the A pillar and the strut tower will substantially change the way the car feels and drives.
Click to expand...

Hi Mario - thanks for jumping in. Tom's comments on how much he liked this particular modification stuck with me, which is why I recounted them here.
 
I have had some great advice from this forum, this has come from both DIY members and professionals.
On one occasion a key professional on this site surprised me by sending me instructions on how to do a job. I have since seen him help many others. He is a great member.
We can probably guess who that was, in my view he strikes the correct balance between business and friendship, however no doubt that the friendship factor will also help his business. Many businesses invest in Relationship Marketing, some may not even realise that they are doing it.
 

Attachments

  • IMG_1332.jpg
    IMG_1332.jpg
    419.5 KB · Views: 428
  • IMG_1333.jpg
    IMG_1333.jpg
    392.3 KB · Views: 392
  • IMG_1491.jpg
    IMG_1491.jpg
    413.6 KB · Views: 404
  • IMG_1477.jpg
    IMG_1477.jpg
    459.9 KB · Views: 399
  • IMG_1345.jpg
    IMG_1345.jpg
    373.8 KB · Views: 396
  • IMG_1497.jpg
    IMG_1497.jpg
    363.9 KB · Views: 408
Here is the rear seat cross strengthening with the tie in to the frame rails. I also replaced the seat mounts with something a little stronger and tied those into the frame rails too. The frame rails protrude in the rear but these are compensated for by sound proofing and dynamat.
 

Attachments

  • IMG_2024.jpg
    IMG_2024.jpg
    301.5 KB · Views: 418
autokunst said:
What you "buy" from CK or VSR is the service of them doing the work, and the quality that they offer in their work.
Click to expand...


I strongly disagree. In addition to Lahore and quality, you are most definitely buying knowledge acquired over decades to experience. You might call it “intellectual property.”

A good example of what you are talking about was the restoration of Scott’s car. Without a mountain of help Benny’s ability to do quality work was insufficient to get Scott’s car done right.

John
 
At that point just build a really, tight, well done cage and wrap it in leather. The car will get magnitudes stiffer than welding pieces across the floors into the rockers
 
bfeng said:
I strongly disagree. In addition to Lahore and quality, you are most definitely buying knowledge acquired over decades to experience. You might call it “intellectual property.”

A good example of what you are talking about was the restoration of Scott’s car. Without a mountain of help Benny’s ability to do quality work was insufficient to get Scott’s car done right.

John
Click to expand...
Hey John,
Oh jeez. Yeah, I am sure you are right about that. I still want to agree to disagree, but when you use the Benny example it is really hard to disagree. That would have been a real shit show without an owner ACTIVELY involving this group throughout the process. I know I learned a lot (from this group's input) just from following along. It was like reality television, but about a car that I really care about.

That said, this thread is about reinforcement ideas. Whereas the Benny/Scott example was a partial restoration and modifications of a car. I'm not sure that is the same thing. If you are saying that a VSR or a CK knows more (to use your phrase, has more intellectual knowledge) than the collective and freely shared knowledge of this forum, then your point is undeniable. But I don't know if that is the case. I'd bet on the forum, and I feel that supports my previous comment. This group is unique and special.

But please don't roast me over it. I get your point.
 
Give me a couple of days to get some pics up. My back is out right now and I'm quite immobile.
I think Larsen did not want to maintain his site. CoupeKing - well someone could ask them for pics and see what their response is. It's not rocket surgery to fix poor welding and in E9s most of the areas are obvious. I'm surprised roofs don't kink when you look at the design.
There's also information ( somewhere ) about what the various race teams did to strengthen the "Flexi flyer". If I can find it anyone can.
 
bfeng said:
I strongly disagree. In addition to Labor and quality, you are most definitely buying knowledge acquired over decades to experience. You might call it “intellectual property.”

A good example of what you are talking about was the restoration of Scott’s car. Without a mountain of help, Benny’s ability to do quality work was insufficient to get Scott’s car done right.

John
Click to expand...
Agreed, some of it is intellectual property learned from years of experience. Its up to the owner of that knowledge to decide who and how he shares it.

We relocated to northern FL from Boston a couple of years ago. Quality vintage BMW support is just not here or if it is, I haven't found it. The upside is that its forced me to do some of the minor maintenance work myself which has been fun and rewarding. When it came time to rebuild my 02 motor, I shipped my car to VSR/Mario who I have known for 20+ years. Already, a few issues have been uncovered that he identified and will handle routinely that would have been challenging, a learning exercise or most likely, completely overlooked if it had been a shop without that vintage BMW knowledge depth. Mario's shop has rebuilt dozens of 02 motors and no doubt, my new motor will benefit from that knowledge. Good shops are not cheap, but I know I will get my car back completed correctly and if I decide to sell, the price will reflect the VSR provenance.

Three months waiting for pistons...the wait is killing me. The upside is that I've been driving the wheels off my coupe.
 
Maybe I am oversimplifying. But I’m still not sure how adding those stitch welds along seams that have already been welded, and which therefore should not flex, will improve chassis stiffness. The flexing doesn’t come from areas that have been welded. It comes from large areas of thin sheet metal being subjected to torsional forces that should be handled by structural elements such as frame rails. Unless I am missing something (highly likely given that Mario, Coupeking and other respected shops are doing this), it seems to me that simply adding welds to existing ones will strengthen that area and reduce the likelihood of old welds breaking from stress. Every little bit helps. And if you do in enough places, it will probably make a little difference. But that should only marginally affect overall chassis stiffness.

Short of adding a roll cage, the type of structural mods that Rek and Erik and others are doing seems to me to be what will make a real difference. What am I missing here?
 
Last edited:
You must log in or register to reply here.
Back
Top