Z4 M Coupe mods, the ongoing tale...

http://www.zpost.com/forums/showthre...t=63368&page=2
http://www.zpost.com/forums/showthre...t=63368&page=3

Gorgeous!

8 lbs savings... I NEEEEED one... so I keep tell'n myself, hahaha... damn it! Install looks very straight forward.

Don't think of it as 8 lbs, think of it as 8lbs at the top of the car, and think of that 8lbs times about 4 ft, and then you get 32 ft lbs of torque on the car. Still not a lot, saving weight at the top of the car is good. I just like it cuz it looks sick.

Originally Posted by epbrown

Umm, you posted in the thread a few days ago, over on zpost.

-Thanks for reminding me. I'm on 6 forums and in two different sections (E39 and Z4) on three of them - so sometimes I forget

Originally Posted by Dammmittt

Don't think of it as 8 lbs, think of it as 8lbs at the top of the car, and think of that 8lbs times about 4 ft, and then you get 32 ft lbs of torque on the car. Still not a lot, saving weight at the top of the car is good. I just like it cuz it looks sick.

I skimmed thru that post for the install pics & not really reading the details but: is the OEM roof screwed on or glued on?

Originally Posted by caylan

I skimmed thru that post for the install pics & not really reading the details but: is the OEM roof screwed on or glued on?

Both. 4 bolts and glued all around.

So am I to understand that the roof needs to be "treated" after purchase? It needs to be clear coated, correct? Is there a special material that needs to be used?

Any ideas how this would look on a black car? The contrast looks great on lighter colored cars, but sometimes CF just looks like a dirty section of a black car...any thoughts how it would look?

Luminor, i think sixspeed put a coat of laquer on it. You'd probably want to give it a good cleaning and maybe clear coat it when you get it. TCK would be able to give you the best care instructions for it. If you want to see how it would look on a black car, look at some pics of a black M6 with a CFP roof. I think think it looks hot, but you'd have to decide that for yourself. I'm planning on installing mine for christmas

Originally Posted by Dammmittt

Luminor, i think sixspeed put a coat of laquer on it. You'd probably want to give it a good cleaning and maybe clear coat it when you get it. TCK would be able to give you the best care instructions for it. If you want to see how it would look on a black car, look at some pics of a black M6 with a CFP roof. I think think it looks hot, but you'd have to decide that for yourself. I'm planning on installing mine for christmas

Thanks for the quick response, but why laquer instead of just clear coat. I've got a shop that can clear coat it, unless there is a reason to use some other material...? i.e. Laquer.

Link to black M6 w/CF roof:
http://www.m5board.com/vbulletin/showthread.php?t=56757

...looks like it will be very subtle.

Any one have a price on this piece. I could call TC, but figured someone might know off the top of their head...

BTW, please tell me you were kidding about the 32lb/ft of torque... :-)

Based on a Sapphire Black M6 I've seen in the flesh I think a CF roof can look great on black cars. But I don't know about Carbon Black though. The blue tones might clash with the warmer black of the CF.

I'm planning on the roof...not sure about the hood. Sounds like the hood needs to be painted. I guess there's a seem of some kind in it.

The roof panel weighs 8.4lbs and costs 1650.00
The hood weighs 14.4lbs and costs 1600.00

...not sure why the smaller roof panel is more expensive, but that's what they told me.

Originally Posted by rimblas

Both. 4 bolts and glued all around.

& they charge >$50K for that?

At 50K the M Coupe is one of the best performance bargins out there...

Originally Posted by Luminor

Thanks for the quick response, but why laquer instead of just clear coat. I've got a shop that can clear coat it, unless there is a reason to use some other material...? i.e. Laquer.

Link to black M6 w/CF roof:
http://www.m5board.com/vbulletin/showthread.php?t=56757

...looks like it will be very subtle.

Any one have a price on this piece. I could call TC, but figured someone might know off the top of their head...

BTW, please tell me you were kidding about the 32lb/ft of torque... :-)

As far as the laquer goes, I have no idea why he used that instead of clear coat, unless it provides a better seal on the CF than the clear coat paint would. As far as the 32 ft lbs of torque, i was just estimating a quick calculation of 8 lbs times about 4 ft high and that's 32 ft lbs of torque. Now...that's not really the whole story. The force of the 8 lbs is directed down unless the car was flipped on its side. What you really want to look at is, the mass difference in the roof times the lateral acceleration of the car and the height of the mass you are changing if you want the real torque the roof provides on the car.

Originally Posted by Dammmittt

...As far as the 32 ft lbs of torque, i was just estimating a quick calculation of 8 lbs times about 4 ft high and that's 32 ft lbs of torque. Now...that's not really the whole story. The force of the 8 lbs is directed down unless the car was flipped on its side. What you really want to look at is, the mass difference in the roof times the lateral acceleration of the car and the height of the mass you are changing if you want the real torque the roof provides on the car.

OK, so I honestly thought you were kidding. You'll have to excuse my ignorance on the subject, I know next to nothing about physics and the formula for determining a vehicle's torque...but are you honestly saying that you believe removing 8lbs from the roof of an M Coupe will generate any where near 32lb/ft of torque? That means this roof mod would have the same, if not greater, affect on torque production as the 4.10 I just installed...

...if that's the case, I'm ordering one today.

Originally Posted by Dammmittt

As far as the 32 ft lbs of torque, i was just estimating a quick calculation of 8 lbs times about 4 ft high and that's 32 ft lbs of torque. Now...that's not really the whole story. The force of the 8 lbs is directed down unless the car was flipped on its side. What you really want to look at is, the mass difference in the roof times the lateral acceleration of the car and the height of the mass you are changing if you want the real torque the roof provides on the car.

Interesting logic! That logic would remotely (underline remotely) make sense if you were rotating the car on an axis running through the car from the back to the front. Sort of like shoving a telephone pole into the rear glass and come out of the windshield and then rotate the car around the pole. Now extending this notion to the torque at rear wheels is one hell of a stretch!

Originally Posted by Luminor

OK, so I honestly thought you were kidding. You'll have to excuse my ignorance on the subject, I know next to nothing about physics and the formula for determining a vehicle's torque...but are you honestly saying that you believe removing 8lbs from the roof of an M Coupe will generate any where near 32lb/ft of torque? That means this roof mod would have the same, if not greater, affect on torque production as the 4.10 I just installed...

...if that's the case, I'm ordering one today.

Luminor, I'm talking about torque on the chassis of the car, which produces roll, not engine torque which produces pull on the car. Torque = Force * length. Torque is why a wrench helps you loosen bolts and nuts and such...

Originally Posted by Mo Kalali

Interesting logic! That logic would remotely (underline remotely) make sense if you were rotating the car on an axis running through the car from the back to the front. Sort of like shoving a telephone pole into the rear glass and come out of the windshield and then rotate the car around the pole. Now extending this notion to the torque at rear wheels is one hell of a stretch!

OK, well Force = Mass * acceleration right? (I feel like I'm teaching high school physics here)

Anyway...8 lbs is rough estimate of the weight difference anyway, probably more like 10-12 lbs. Well the point of this is that that 8 lbs directed down, is the mass of the object times gravity...lets call that g. The mass difference of the roof is always going to be the same...but the acceleration will change.

Now, you remove that 10-12 lbs. You figure the center of mass of the roof is about 4 ft off the ground...estimate...

So...if you are pulling one g of lateral acceleration of the car, you would LOSE about 40 ft lbs of torque (twist) on the chassis just by virtue of where you lost the weight on the car because that 1 g laterally is like aiming the weight of roof at a 90 degree angle to the normal direction of gravity (like turning the car on its side). All this means for you is when you turn hard, it puts less stress on the car because you where you lost the weight.

Ahhh, I see...I'm with you now that you've made the distinction... ...and thanks for the wrench, bolts and nuts example but I do get the general concept of torque

Originally Posted by Dammmittt

....I'm talking about torque on the chassis of the car, which produces roll, not engine torque which produces pull on the car......

Ah, OK. That's a different story. I thought you were talking about torque at rear wheels..
My mistake.

Originally Posted by Dammmittt

Now, you remove that 10-12 lbs. You figure the center of mass of the roof is about 4 ft off the ground...estimate...

-Except that 4' off the ground doesn't matter. What matters in your argument is the change of weight relative to the roll center of the vehicle, not the ground.

Originally Posted by Palantirion

-Except that 4' off the ground doesn't matter. What matters in your argument is the change of weight relative to the roll center of the vehicle, not the ground.

Yup... distance is taken from CG, not ground. So, moment acting on the cg due to weight savings of cf roof is probaly closer to the order of 10~15 ftlb. Basically, neglible.

Originally Posted by stephenti

Yup... distance is taken from CG, not ground. So, moment acting on the cg due to weight savings of cf roof is probaly closer to the order of 10~15 ftlb. Basically, neglible.

-I would use the term "minor" instead of "negligible". Minor x several = substantial

Originally Posted by Palantirion

-Except that 4' off the ground doesn't matter. What matters in your argument is the change of weight relative to the roll center of the vehicle, not the ground.

Good point...anyone know where the CG is on the MCoupe? Oh!!! and when you lose weight on the top, you also move the CG...but like we said...10 lbs on a 3200 lb car kinda minor...but like I said, I like it more than anything cuz it looks HOT!

Originally Posted by Dammmittt

Luminor, i think sixspeed put a coat of laquer on it. You'd probably want to give it a good cleaning and maybe clear coat it when you get it. TCK would be able to give you the best care instructions for it. If you want to see how it would look on a black car, look at some pics of a black M6 with a CFP roof. I think think it looks hot, but you'd have to decide that for yourself. I'm planning on installing mine for christmas

I had it clear-coated - that was all

If you get one you may or may not need it done. The roof was already finished for install straight away (and TCK didn't mention any need for further treatment etc before fitting).

However, when I inspected mine, there were light scratches in the resin/clear-coat that was already on there. So I asked a friend of mine who runs a bodyshop to add another clear-coat layer. Not only will this help protect the carbon from UV damage (as there is a UV inhibiter in the clear, and carbon can discolour over time from sun exposure), but it also meant they could safely flatten the new coat back until it looked like glass Which it sure does now!


Alpine White Z4M Coupe
19" CSLs w/ PS2s -- TCK Carbon Roof -- Gruppe-M Intake -- H&S Cat-Back -- H&R Springs -- Tints -- Storm V1 -- CDV -- DICE -- +more

Originally Posted by sixspeed

I had it clear-coated - that was all

If you get one you may or may not need it done. The roof was already finished for install straight away (and TCK didn't mention any need for further treatment etc before fitting).

However, when I inspected mine, there were light scratches in the resin/clear-coat that was already on there. So I asked a friend of mine who runs a bodyshop to add another clear-coat layer. Not only will this help protect the carbon from UV damage (as there is a UV inhibiter in the clear, and carbon can discolour over time from sun exposure), but it also meant they could safely flatten the new coat back until it looked like glass Which it sure does now!

Good to know, thanks. I'm definitely going to have mine shot with another coat of clear just to make sure its got the UV protection it needs.