M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Suspension => Topic started by: martihe1 on August 16, 2008, 05:50:06 AM
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Hi all
My first post to this pretty awesome forum. Does anyone know where I could find info regarding body stiffening. In other words, what parts of E30 body should be welded to make it stiffer?
Thanks for advance
H
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I can't believe no one has posted in this thread, seems cool to me. It's common for people to stitch weld the engine bay to increase rigidity, but I'm not sure I have heard of anyone doing it with an e30. Also there are front strut braces as well rear ones, which people don't rave about. I'm curious myself to the extent of chassis stiffening that can be done to e30s involving bracing and the like. Anyone have any experience with it?
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Get an E36
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Why not E46 m3?...
Well, I think that was not the answer he was hoping for. It's quite common that E30's is track use are welded for extra rigidity. Question is that how it is done.
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I can confirm from personal experience that body stiffness wise E46 > E36 > E30 :)
My E36 Sedan body is starting to feel bit flexy, doors seams make annoying noises on bumps etc. My E46 M3 feels like it is hewn from solid piece of metal.
I did read the original question when it was posted but since I do not have any practical knowledge what should be spot welded on E30 to make it more rigid, I did not answer. I guess you should basically spot weld everything you can. But I have a feelign that proper cage tied to car's body in proper places is far better choice than spot welding.
Since my E36 318is is becoming less and less road car and more and more track car, I have thought about building a cage for it. Swiss (Tony) posted some good shit about E36 Supertouring tech on his thread:
http://www.m42club.com/forums/showthread.php?t=4749
(http://i244.photobucket.com/albums/gg19/swiss318is/DSC00135.jpg)
(http://i244.photobucket.com/albums/gg19/swiss318is/DSC00138.jpg)
Before I was bit apprehensive about putting too much effort on my 318is because if in future I want to have huge horsepower and keep the car road "legal" the car should be M3.
But it seems that iron block S50's really kill the weight distribution (friends stripped and caged M3 is 70 kg heavier on front than rear!) and the engines are still only 3,2 liters max. I can legally put 2,8 or M52 or 3,0 M54 to my 318is which are lighter due alloy block and not much behind on ultimate power capability if well built.
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Hi all
My first post to this pretty awesome forum. Does anyone know where I could find info regarding body stiffening. In other words, what parts of E30 body should be welded to make it stiffer?
Thanks for advance
H
Get a solid strut bar that mounts to all the nuts on the top of your shock tower. Than upgrade your stock swaybars and you will out handle any car
E36 < E30 According to every BMW tech I know
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Hey DUDES!
He is asking about welding and your are offering strut bars. He's asking for beer and you are offering girl drinks :). he is well aware of strut bars.
To my understanding the car is stripped and removed from all sound insulation material. After that it is sand blasted. Then it will be spot welded trough put the body (all seams). He is looking for a website etc. which would describe the procedure in detail.
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Hey DUDES!
He is asking about welding and your are offering strut bars. He's asking for beer and you are offering girl drinks :). he is well aware of strut bars.
To my understanding the car is stripped and removed from all sound insulation material. After that it is sand blasted. Then it will be spot welded trough put the body (all seams). He is looking for a website etc. which would describe the procedure in detail.
i dont see how you got all this information from his first initial post... weird.. its ok i dont care if you think your new car is stiffer than an old car. Its pretty obviously a 17 year old car is gonna have a few more loose bolts in the suspension but it can be fixed. ANYWAY
I did notice on the cabrio that they did some extra reinforcements to the chassis. Look at the extra welds on a cabrio and you may find the answer you are looking for.
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Hey DUDES!
He is asking about welding and your are offering strut bars. He's asking for beer and you are offering girl drinks :). he is well aware of strut bars.
To my understanding the car is stripped and removed from all sound insulation material. After that it is sand blasted. Then it will be spot welded trough put the body (all seams). He is looking for a website etc. which would describe the procedure in detail.
so do you have some input on where he should look or are you gonna sit there and act like a douche?
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i dont see how you got all this information from his first initial post... weird.. its ok i dont care if you think your new car is stiffer than an old car. Its pretty obviously a 17 year old car is gonna have a few more loose bolts in the suspension but it can be fixed.
Actually, I think he did not refer to original post, just how the spot welding is done generally. So he is actually adding information to this discussion :)
And it is just not about loose bolts. Every new 3 series generation has torsionally stiffer body straight from factory line, even without taking account the aging effect on older bodies.
I have seen with my own eyes endurance class SEAT Ibiza that had so tired body due fatigue that while it was standing still and you rocked it from left to right you could see the gaps between fenders and hood changes 1/4th of and inch! :eek:
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...Swiss (Tony) posted some good shit about E36 Supertouring tech on his thread:...
hmm.. who is Tony?? :D
i would say.. stitch-weld the whole chassis.. all seems you can find.. first clean it from colour and then.. WELD WELD WELD.. have fun.. there are at least 100km of welding in front of you..
thats what i am gonna do with my white car.. and then a bolted rollcage and strutsbraces front and rear.. i think that all will increase the rigidity of the car more than enough.... perhaps a sheetmetal here and there too.. :D
but dont forget.. the oldest e30 318is are 20years old!!!
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I suppose good starting point is to check out how factory did it for example on M3. There are lot of improvments, not just aerodynamical for extra strenght.
Some how i find it out a little bit funny we finns discuss on US based forum in english when there are finnish BMW forums where you you can write finnish :)
I also suggest you to visit some finnish rally events.There are lots of E30 bodied BMW's. Just disccus with these people, they can give you some useful information.
Here's some finnish low cost rally cars:
(http://i5.photobucket.com/albums/y170/olli951/bmw7.jpg)
(http://i5.photobucket.com/albums/y170/olli951/bmw6.jpg)
(http://i5.photobucket.com/albums/y170/olli951/bmw5.jpg)
(http://i5.photobucket.com/albums/y170/olli951/bmw3.jpg)
(http://i5.photobucket.com/albums/y170/olli951/bmw2.jpg)
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First thing i noticed was the M3 has a pillar coming out the back of the strut tower.. That's a start... I pointed out earlier that the cabrio has a reinforcement on the top of the front shock towers. No pics though.
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Reasons why M3 had different rear window arrangement where aerodynamics and the other was extra reinforcement just under rear window. Rear window is the same as normal E30 body uses it has just moved back using glassfibre frame.
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M3 front and rear windshields are glued in to provide extra stiffness, unlike the normal E30.
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for a good start, you could do the strut tower braces. they are kinda expensive, but if you have the resources, you can pretty much make them yourself (with a welder)
Another option would be the b-pillar cross bar (hence taking out access to the back seat...)
front and rear sway bars and you should be tight like my other favourite thing...;)
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The biggest problem with stitch welding the chassis is that it will take alot of work. You need to go all out and have all the right tools to do it properly. I do not know what your situation is as far as having a shop or garage. So I will just shoot some things out.
The only right way to stitch weld the chassis is to do every seam on the car. It is a unibody design and it should have that unibody riggedness. Meaning each part relys on the others attached to it for strength. The car should be disassembled to do this, and dipped to remove all adhesives and coatings. This however is a tremendous about of work and money.
I would suggest welding the problem / weak areas of the car first. Such as everything around the rear subframe mounts and all around the trunk area. Shock mounts too. Up front there isn't a whole lot to do unless you get creative. Stitch the seams around the strut mounts. Plating around the strut mounts would add some strength too. I agree that strut braces are a good solution front and rear. Easy and bolt on. Be careful as some aluminum bars are not a stiff as you would think. Steel is heavier, but it is cheaper and stiffer.
Overall strength is only as good as it's weakest point. Get reinforcement kits for everything on the e30. Turner Motorsports makes a nice complete kit. If you are handy with metal you can fab things on your own. Just remember the strong welds are clean welds. You need to get all the adhesive out of the area you are going to weld. Dirty welds = useless welds.
All of these little things combined will add alot of stiffness to your car.
All of these braces and reinforcement should be done anyway if your going to track the car. Truct me things break and cracks spread fast! You would want them done before you do a cage because stiff cage equals weak car. (Hint: weakest point!)
Good luck and we love pictures here. :)
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so do you have some input on where he should look or are you gonna sit there and act like a douche?
Yeah dude, the smiley at the end of it implies he is kidding around, jeeez. ;)
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Check out this site.
It might be some help.
http://www.aceengineering.ca/stitch_welding.asp (http://www.aceengineering.ca/stitch_welding.asp)
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During weekend I read book about different 3-series. Not sure how reliable their data is but this is what they said about torsional stiffness:
E36 30% better than E30
E46 45% better then E36
So is E30 is 100% as baseline then:
E36 is 130%
E46 is 182%
There are small variations between sedan and coupe models.
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Well if i had the money it would be one of the first things i would do. I find that if i go over a speed hump or drive way on an angle i can here the parcel shelf and door interior panels move as the body twists slightly.
I also know a guy that has a commodor (Australian Car) put some stiff as springs on an in 6 months the car had warped one wheel didn't even touch the ground!!! But then again it is a commodor.
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Without doing a full race-prep roll cage and butressing, people usually put a strut brace in the front and weld a strut brace between the rear shock turrets under the parcel shelf (inside the boot).
Thicker roofskins with no sunroof also help but that's also major surgery.
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Here's something about seam welding:
http://forums.bimmerforums.com/forum/showthread.php?t=1093968
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about BMWs structural torsional stiffness:
BMW E36 Touring 10,900 Nm/deg
BMW E46 Sedan (w/o folding seats) 18,000 Nm/deg
BMW E46 Sedan (w/folding seats) 13,000 Nm/deg
BMW E46 Wagon (w/folding seats) 14,000 Nm/deg
BMW E46 Coupe (w/folding seats) 12,500 Nm/deg
BMW E46 Convertible 10,500 Nm/deg
BMW Mini : 24,500 nm/deg
BMW E90 : 22,500 nm/deg
BMW Z3 cabrio 5,600 Nm/deg
BMW M roadster: estimate 6300 Nm/deg
BMW Z3 M coupe 16,400 Nm/deg
BMW Z4 cabrio: 14,500 Nm/deg
BMW Z4 M Coupe : 32,000 Nm/deg (BMW AG's press)
dynamic stiffness:
BMW Z3 M Coupe: 29.2 Hz,
BMW Z4 Roadster: 21 Hz
BMW E36 M3 coupe: 29.2 Hz
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the best way to reduce suspension and body movement is to replace all rubber bushings or mounts in the suspension system with heims joints which will remove any bushing deflection. the most important place to do this is at the rear of the front lower control arms. this will make the feel of the ride a lil bit rough but the increased handling should be totally worth it.
a mod like this would be the first step before going to reinforce the rest of the vehicles structure
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the best way to reduce suspension and body movement is to replace all rubber bushings or mounts in the suspension system with heims joints which will remove any bushing deflection. the most important place to do this is at the rear of the front lower control arms. this will make the feel of the ride a lil bit rough but the increased handling should be totally worth it.
a mod like this would be the first step before going to reinforce the rest of the vehicles structure
I've never heard of a heims joint, what are they?
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Here you are, heim joints! http://en.wikipedia.org/wiki/Heim_joint
Search google for 'heim joint E30' maybe? I've not tried. Poly bushing will help the car feel 'tight'.
Seam welded along all SEAMS. Search google for seam welding photo's to know the style (seems to be inch of weld, 1/2 - inch non weld, then weld again).
Then rollcage, and boy will your car be stiff!
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did someone stitch-weld his e30??