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E36/7 Z3 (1996-2002)
E36/7 Z3 Roadster, Z3 coupe, Z3 M Roadster and Z3 M Coupe talk with our gurus here.

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  #1  
Old 03-25-2013, 02:00 AM
baxterross baxterross is offline
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How soon would I regret this decision (shock tower seam separation)

In looking at a couple of M Roadsters over the weekend, I some pictures of some cracks I found on the front shock tower weld seams.
Needless to say, I haven't purchased this car, and I wanted to get an impression of how serious an issue this is and whether or not it is a deal breaker or just a price reducer



Thanks,
-Baxter
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  #2  
Old 03-25-2013, 06:45 AM
dougmcintyre dougmcintyre is offline
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"When in doubt, pass" is my motto when buying used cars. Yea, I miss some good deals. But I lower my odds of buying a money pit.

Before even considering buying this car, I'd have a repair estimate from the best body shop in my area . If the owner refused to take the car to the body shop of my choice, pass.

Also, the rust spots bother me. I could be mis-reading the pics, but there seem to be 5 to 8 incidental rust spots/patches. As I don't have a garage, my car has been parked outside for 6+ years. Zero rust under the hood.

Which raises the following questions:
Why have these rust spots occurred? How rusted is the rest of the engine bay? If not, why is the rust only in this area? Why hasn't the owner fixed this easily repaired rust? Has the owner neglected other issues?

The more pristine the rest of the car is, the more the pictured rust would bother me.

On the other M roadster, were there similar rust spots?

Last edited by dougmcintyre; 03-25-2013 at 07:19 AM.
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  #3  
Old 03-25-2013, 11:12 AM
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Randy Forbes Randy Forbes is offline
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What rust spots? It looks to be pretty clean to me! Perhaps the (enormously inappropriate for posting on a forum...) size of the pictures is throwing you off, but all I can see__unless I'm missing something__is the tiniest of paint chips that might be discolored underneath.

As for the cracks in the seam sealer, I wouldn't consider that to be a deal-breaker at all; if and when an owner chooses to do so, that is very easily rectified. When I encounter them, I typically hammer the seams flat again__it only takes a few relatively light taps, and the steel in that area is quite ductile__and then braze over the edges using silicon-bronze rod and a TIG torch. The TIG process allowing for minimum heat and a very controlled arc.

I'd be much more concerned about the condition of the trunkfloor and rearmost differential mount, though again, not a deal breaker, depending on the seller. If you do find damage at the rear end, and they will all have it someday (regardless of how the car has been driven, as road conditions, like the ones that can cause the front strut tower seams being stressed). If you're so inclined to proceed, and do find evidence of the rear end requiring work, I'd try to get the seller to take the cost of the repair into consideration, covering all or a portion of the work. I'd be leery of unapproved repairs however, as there's some pretty ugly stuff floating around on the internet. Feel free to contact me offline (email in signature) if you have any specific questions relating to this work.

So, did you like the rest of the car...?
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  #4  
Old 03-25-2013, 12:26 PM
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vintage42 vintage42 is offline
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Quote:
Originally Posted by Randy Forbes View Post
... I'd be much more concerned about the condition of the trunkfloor and rearmost differential mount... they will all have it someday regardless of how the car has been driven...
Even a 1.9L that is just driven on highways in a sporting manner?
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  #5  
Old 03-25-2013, 12:38 PM
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Randy Forbes Randy Forbes is offline
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Originally Posted by vintage42 View Post
Even a 1.9L that is just driven on highways in a sporting manner?
There was at least one (Z3SPEED4ME on Bimmerforums) and for a long time, it was the worst-most torn up-one example we'd seen; there have since been cars as bad or worse.

I was really making the case for the ///M versions, but the 3.0 doesn't lag much behind the S-52 as far as horsepower goes (225 vs 240). And, there are plenty of modded 2.8s running around__I'm putting a supercharger on one right now.

I've personally fixed a pretty bad 2.3 (Long Island, NY) that justified swapping in an entire new trunkfloor, like a dealership would do__except I added the reinforcement too.

About the only model that I've neither seen damaged, nor fixed one myself, is that fitted with an automatic transmission. Gives you some idea of the amount of horsepower and torque they absorb, doesn't it
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Randy Forbes
1957 Austin-Healey 100/6 Wine Red
1961 McCulloch R1 go-kart Screaming Yellow
1995///M3 Coupe Dakar Yellow Eurosport Twinscrew S/C
1999///M Rdstr Cosmos Black Eurosport Twinscrew S/C
1999///M Coupe Estoril Blue Eurosport Twinscrew S/C
2001///M Rdstr Steel Gray
2011 X5 35i Sport Deep Sea Blue/Cinnamon
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  #6  
Old 03-25-2013, 01:11 PM
dougmcintyre dougmcintyre is offline
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Quote:
Originally Posted by Randy Forbes View Post
...
As for the cracks in the seam sealer, I wouldn't consider that to be a deal-breaker at all; if and when an owner chooses to do so, ...
What is the risk in not fixing the seam sealant cracks? Is the seam sealant purely cosmetic?
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  #7  
Old 03-25-2013, 02:08 PM
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vintage42 vintage42 is offline
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Originally Posted by Randy Forbes View Post
There was at least one (Z3SPEED4ME on Bimmerforums) and for a long time, it was the worst-most torn up-one example we'd seen; there have since been cars as bad or worse...
Not clear if you mean more 1.9s as bad or worse, or just more Z3s. I looked up Z3speed4me's case, a NJ college student in 2005 with a 1.9 that had 67,000 miles. Maybe it had been driven hard before and he was the last straw. Mine has 33,000 miles, all the owners over 65, so maybe there's hope the subframe will hold up.
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  #8  
Old 03-25-2013, 03:56 PM
Z3Papa Z3Papa is offline
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My car has had smaller fractures around the strut tower but much closer to the top which I think were probably stress fractures from camber plates. My co-driver and I welded them nice and clean, and installed the reinforcement plates. No problem since. This is much further down the tower which is kind of surprising but not impossible to fix. Seems like that would be a byproduct of some side impact.
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  #9  
Old 03-25-2013, 04:34 PM
baxterross baxterross is offline
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Thanks for the great info guys. I haven't had a chance to get the car to mechanic yet, but otherwise it felt pretty good.
What kind of things should I be looking for in regards to shift pin wear? That's really my only other major concern on the car.
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  #10  
Old 03-27-2013, 03:03 PM
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Randy Forbes Randy Forbes is offline
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Quote:
Originally Posted by dougmcintyre View Post
What is the risk in not fixing the seam sealant cracks? Is the seam sealant purely cosmetic?
The sealant itself, as I'm sure you know, is primarily to keep moisture from getting between the spot-welded panels, so kinda cosmetic. The fact that the seam sealer has cracked indicates there's been some movement; so the tower flexed in (or out) pushing against the flange, then moves back out (or in) and the flange stayed raised, breaching the sealed seam.

With enough of that movement__and I have no idea how much that would take, but someone that races their E-36 or Z3 may have an idea__the spotwelds would eventually be subjected to the bending forces and fracture.

It doesn't take much to tap the flanges back flat, braze the edges and re-seal the seams, and then it's up to the person doing the work how it's finished off at that point. Since I have all the Z3/M colors in stock, including a few of the underhood-specific ones, I feel compelled to make the repairs that I do invisible.

My way of gaging the severity of the seam separation...









Undersides need to be resealed too:







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1957 Austin-Healey 100/6 Wine Red
1961 McCulloch R1 go-kart Screaming Yellow
1995///M3 Coupe Dakar Yellow Eurosport Twinscrew S/C
1999///M Rdstr Cosmos Black Eurosport Twinscrew S/C
1999///M Coupe Estoril Blue Eurosport Twinscrew S/C
2001///M Rdstr Steel Gray
2011 X5 35i Sport Deep Sea Blue/Cinnamon
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  #11  
Old 03-28-2013, 12:28 AM
baxterross baxterross is offline
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Thanks Randy for the super comprehensive answer, can't believe I didn't think to stick something in the crack to see if the spot welds had separated.
How does one go about purchasing one of your trunk floor kits?
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  #12  
Old 03-28-2013, 12:28 AM
baxterross baxterross is offline
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Thanks Randy for the super comprehensive answer, can't believe I didn't think to stick something in the crack to see if the spot welds had separated.
How does one go about purchasing one of your trunk floor kits?
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  #13  
Old 03-28-2013, 03:59 AM
dougmcintyre dougmcintyre is offline
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Quote:
Originally Posted by Randy Forbes View Post
The sealant itself, as I'm sure you know, is primarily to keep moisture from getting between the spot-welded panels, so kinda cosmetic. ...
That's why I was surprised at your "if and when" answer. As a former British car owner, my MG Midget taught me quickly fixing the first possibility of any rust was the best and easiest way to deal with rust.
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  #14  
Old 03-29-2013, 03:10 AM
Kornknarr Kornknarr is offline
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Good thread and thanks Randy for posting the images. I went out and had a look on my car so I now have a new welding project for next winter...
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  #15  
Old 11-19-2013, 06:00 AM
BryZzz BryZzz is offline
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Hi Randy,

I have the exact same problem on my 2.8 Z3 shock/strut tower location and side. Did i see it right? You TIG welded the cracks and re applied silicon sealant after? I wish i was in the states, this would have been such an easy problem to solve.
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  #16  
Old 11-19-2013, 06:31 AM
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Randy Forbes Randy Forbes is offline
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I used a TIG torch and silicon-bronze brazing rods. You don't have to "melt" the steel to braze the flanges back down, as it's a lower temperature process. Given that the spot welds haven't actully failed, brazing makes sense for this application. You can do brazing with an acetylene torch too (actually a lot easier than with a TIG).

That's not a silicone sealant, nor would I recommend the use of silicone there (it will corrode underneath), but any decent autobody paint shop will carry an appropriate polyester type seam sealer to use. 3M products Fast-n-Firm in a caulk tube works well (just smooth it over with a popsicle stick).

Considering your location, I hope that cracking strut towers is your biggest concern right now! All those unfortunate people along the coast!
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1957 Austin-Healey 100/6 Wine Red
1961 McCulloch R1 go-kart Screaming Yellow
1995///M3 Coupe Dakar Yellow Eurosport Twinscrew S/C
1999///M Rdstr Cosmos Black Eurosport Twinscrew S/C
1999///M Coupe Estoril Blue Eurosport Twinscrew S/C
2001///M Rdstr Steel Gray
2011 X5 35i Sport Deep Sea Blue/Cinnamon
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  #17  
Old 11-19-2013, 07:57 AM
BryZzz BryZzz is offline
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Hi randy,

Thanks for your prompt response, I go to a shop that does both body repair and customized mufflers. Given that they are equipt with an acetalyn torch and a tig welding machine, do i still stick with the acetalyn?

Please let me know if what i have in mind will work:
1) have tinsmith hammer gently on the cracked area to flatten out(although it doesn't look like its far apart from each other);
2) welder apply some low heat for the seams to meet;
3) after heating, apply some putty?;
4) dry out and paint over.

*under carriage would have to be treated as well right?
** im sure the peeps in the bodyshop would know how to do this, but id still want to give out proper instructions as most of the shops here are used to hammering japanese cars

Since you mentioned my fellow Filipino Peeps, I'm glad to say that we've received an overwhelming amount of love and help from everyone across the globe, a lot of lives lost, livelihood that may never be recovered, but we are known to be resilient and people of strong faith.

Please include my country in your prayers!

Cheers!
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  #18  
Old 11-20-2013, 06:22 AM
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Randy Forbes Randy Forbes is offline
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You've got it; everything you've outlined is good. If the guy doing the job is better with a torch than a TIG, then that's the way to go. If it's the other way around, then he uses the TIG. Both can get the job done

Yes, definitely recoat the underside to prevent corrosion in the future. Good preparation is a must if the coating is to stick well.
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1957 Austin-Healey 100/6 Wine Red
1961 McCulloch R1 go-kart Screaming Yellow
1995///M3 Coupe Dakar Yellow Eurosport Twinscrew S/C
1999///M Rdstr Cosmos Black Eurosport Twinscrew S/C
1999///M Coupe Estoril Blue Eurosport Twinscrew S/C
2001///M Rdstr Steel Gray
2011 X5 35i Sport Deep Sea Blue/Cinnamon
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  #19  
Old 11-20-2013, 06:28 AM
BryZzz BryZzz is offline
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Hi randy,

my techncian is pretty good with both, but ok, ill have him use the torch, is there a proper mix of gasses for the chassis? Or do i just trust him with it?

Thanks so much!
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