I posted this on Bimmerforums last week but it's much more pertinent here.
Just an idea I've been mulling over, I think I'll try it when I get my new E30.
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I'm going to be converting diving boards to plastic bumpers for a car that's not going to get many street miles...and I thought instead of putting on the stock fluid-filled bumper shocks from a late-model E30, can I just weld up some brackets to hold the bumper the right distance from the body?
Might not be too safe for street use, but on the track I doubt it would make much difference in the event of an impact.
I've never held a bumper shock in my hand so I don't know how heavy they are, but I assume they are heavier than just a piece of 1.75" steel DOM with a flat plate welded to one end (car side) and a smaller ID tube welded to the other end (bumper side).
Looking at the diagrams found in the ETK, it appears that there is no reason this idea couldn't work.
Instead of the hydraulic cylinder extending back behind the bumper, there would be a flat metal plate that would bolt to the stock attachment points and covert he hole. A piece of DOM would be welded to this plate, in place of what used to be the shock tube. Then the appropriate angle pieces and fittings could be welded to that to give a stock function -- minus the crumple/hyrdaulic enger absorption "features" of the OEM bumper shock.
One source has estimated the bumper shock weight at 10lbs each. I think that the design I'm talking about could be under two lbs.
Rear shock is part #13:

If one wanted to retain some of the safety benefit of the stock bumper shock, a simple idea would be to use a larger inner diameter DOM tube with a smaller outer diameter DOM tube sleeved into it. This would duplicate the look of the stock bumper shock, more or less.
You would tack weld the smaller tube inside the bigger tube so that it sticks out a few inches, and the idea is that in an accident the tack welds give way and the bumper can move in.
It's just occurred to me that on the front bumper shock there is a threaded hole for the tow hook. This could be duplicated on my version, but the simpler way would be to use one of Turner Motorsports' tow strap which eliminates the need for the tow hook.
Connect to: http://www.turnermotorsport.com/html...PRODUCT_ID=TOW
I'm not sure how it connects to the bumper shock, but it seems at first glance to be easier to fab a way to connect that strap than to thread a tube for the stock tow hook.
Of course, a nut with the appropriate sized threads could simply be welded to the end of a hollow tube, but I can't say how strong that would be and you are pulling the car by this point, after all.

As for the little cylinder that the bumper attachment bolts thread into, that could be cut off the stock bumper shocks and welded to the new pieces.
Just an idea I've been mulling over, I think I'll try it when I get my new E30.
___
I'm going to be converting diving boards to plastic bumpers for a car that's not going to get many street miles...and I thought instead of putting on the stock fluid-filled bumper shocks from a late-model E30, can I just weld up some brackets to hold the bumper the right distance from the body?
Might not be too safe for street use, but on the track I doubt it would make much difference in the event of an impact.
I've never held a bumper shock in my hand so I don't know how heavy they are, but I assume they are heavier than just a piece of 1.75" steel DOM with a flat plate welded to one end (car side) and a smaller ID tube welded to the other end (bumper side).
Looking at the diagrams found in the ETK, it appears that there is no reason this idea couldn't work.
Instead of the hydraulic cylinder extending back behind the bumper, there would be a flat metal plate that would bolt to the stock attachment points and covert he hole. A piece of DOM would be welded to this plate, in place of what used to be the shock tube. Then the appropriate angle pieces and fittings could be welded to that to give a stock function -- minus the crumple/hyrdaulic enger absorption "features" of the OEM bumper shock.
One source has estimated the bumper shock weight at 10lbs each. I think that the design I'm talking about could be under two lbs.
Rear shock is part #13:

If one wanted to retain some of the safety benefit of the stock bumper shock, a simple idea would be to use a larger inner diameter DOM tube with a smaller outer diameter DOM tube sleeved into it. This would duplicate the look of the stock bumper shock, more or less.
You would tack weld the smaller tube inside the bigger tube so that it sticks out a few inches, and the idea is that in an accident the tack welds give way and the bumper can move in.
It's just occurred to me that on the front bumper shock there is a threaded hole for the tow hook. This could be duplicated on my version, but the simpler way would be to use one of Turner Motorsports' tow strap which eliminates the need for the tow hook.
Connect to: http://www.turnermotorsport.com/html...PRODUCT_ID=TOW
I'm not sure how it connects to the bumper shock, but it seems at first glance to be easier to fab a way to connect that strap than to thread a tube for the stock tow hook.
Of course, a nut with the appropriate sized threads could simply be welded to the end of a hollow tube, but I can't say how strong that would be and you are pulling the car by this point, after all.

As for the little cylinder that the bumper attachment bolts thread into, that could be cut off the stock bumper shocks and welded to the new pieces.
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