Z4 Hardtop Mechanism Weight

[niteflyiv]

Any thoughts on how much all of the hydraulics, arms, etc. to open and close the hardtop weigh?

or put another way...

If one were to weld or bolt their hardtop "closed"/up, how much weight could saved by removing all of the ancillary equipment?

[Asbjorn]

No one knows. But consider studying the weight difference between an E92 and E93 or similar. With the 4 series there is a 225kg weight difference, but some of it might be due to stiffening of the chassis and a heavier roof. The problem is that the trunk needs to be able to open both ways, adding weight, and it is hard to modify it so that it only opens one way or not at all.

I would say removing both the side windows and the entire roof and hydralics is the only way to get a noticable performance increase. I for one might be interested in doing this when the Z4 becomes older.

[rking117]

From looking at the hydraulics modules in the trunk (next to the battery) and judging the size of the hoses and such to connect them, these would really be the only components you would be able to remove. The real weight comes with the hinges and stiffening structures in the roof area. You would have to remove them as well, so to make a coupe so to say out of this it would require some significant engineering and construction. I am guessing that motors, hoses and fluid weights some where around 30 pounds max.

[wmandra]

My estimate is that the entire convertible top module weighs somewhere in the neighborhood of 300-400 lbs. FYI, It's possible to remove the entire roof module including all hydraulics and mechanisms in one shot. If you're serious about attempting it, shoot me a PM and I will send you instructions from BMW on how to remove everything.

[rking117]

Originally Posted by wmandra

My estimate is that the entire convertible top module weighs somewhere in the neighborhood of 300-400 lbs. FYI, It's possible to remove the entire roof module including all hydraulics and mechanisms in one shot. If you're serious about attempting it, shoot me a PM and I will send you instructions from BMW on how to remove everything.

That would mean removing the top completely correct? I didn't see a way to separate the top from the mechanism and still make it safe.

[ojo]

Don’t think there is much weight to save. Edscha, the producer bmw use for retractable roof on their cars claim they “have pioneered innovations including the light weight roof of the BMW Z4 with a total weight of only 24 kg”. Not sure if all components are included (seem to remember bmw said that the complete roof system on e89 weighs about 50kg)

[wmandra]

Originally Posted by rking117

That would mean removing the top completely correct? I didn't see a way to separate the top from the mechanism and still make it safe.

yup, that's the whole thing roof panels and all

[niteflyiv]

Originally Posted by wmandra

My estimate is that the entire convertible top module weighs somewhere in the neighborhood of 300-400 lbs. FYI, It's possible to remove the entire roof module including all hydraulics and mechanisms in one shot. If you're serious about attempting it, shoot me a PM and I will send you instructions from BMW on how to remove everything.

Thanks for the offer.

My thought would be to take it all off the car, and everything apart. Then, between a combination of welding, gluing and/or bolting, create a hardtop; which could in-turn be welded, glued, and/or bolted to the car to make a "coupe". I'm sure some fabrication would be in order.

Or maybe remove everything and evaluate using a GT3 top.

[wmandra]

Originally Posted by niteflyiv

Thanks for the offer.

My thought would be to take it all off the car, and everything apart. Then, between a combination of welding, gluing and/or bolting, create a hardtop; which could in-turn be welded, glued, and/or bolted to the car to make a "coupe". I'm sure some fabrication would be in order.

Or maybe remove everything and evaluate using a GT3 top.

I would completely remove everything and look into a fiberglass top. Nothing in the convertible top module is structural, so it can all safely go. Problem with the GT3 hard top is going to be cost as its carbon fiber and made to bolt into the race car (which is dramatically different than the street car).

-b

[rking117]

I think it may be possible to use a GT3 top you will have to remove the current top completely and then have some attachment points welded to the frame structure as attachment points. As far as size goes i haven't done the side by side comparison so i would definitely do that before you go this route. Also note that you may have to get some panels moded to make it work correctly and without leakage from rain etc.