[968 Cab]

I finally decided today was the day to rip out the stupid sub and relocate the amp and CD changer that the PO had installed... well now I know why they didn't hide the CD changer, mounting it on a board on top of the PS cubby in the trunk (cutting the carpet and ruining it at the same time too) - well, here is the most interesting piece of Porsche Engineering I have seen.



PN 781 242-3

V-67XO-1709-EXXX



Why did they stick that in the trunk - to rebalance the car?? It must weigh 48+ lbs! Sure is nicely bolted down, cause I sure wouldn't like to be in the way of that LUMP flying at your head in an accident!!!



Anyone else remove this thing? Any adverse effects? I think the gas mileage will soar with it out!

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[Greimann]

That thing is technically a TMD, tuned mass damper. When you cut the roof off of a coupe to make a convertible 968, you change the vibration characteristics of the body. Adding that weight cancels out undesirable harmonic vibrations that one may see in certain road conditions. If you find that there is undesirable body shake, or loose handling, then put it back in, otherwise leave it out and enjoy the ride. . if I had a cabrio, I think I would have removed it too!

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[BruceWard]

This is a heavily debated topic. Some feel that this unneeded weight (perhaps left over from an outdated design) should be removed from the car. Others feel that it is a needed damper that Porsche engineers knew the car needed.



Personally I took mine out for two weeks. During that time I did some street driving, high speed cornering through the Ozarks and ran a SCCA Autocross. I did not notice a benefit to having it out so I put it back in.



I am certainly in the minority on this forum having a cab with a damper.



For any competitive PCA events I would have the damper in. Otherwise your Cab will be bumped to an undesirable class. At PCA Autocross events each driver is given the opportunity to inspect other cars after the runs are over. If damper was found to be missing after running the days events the driver could be disqualified or bumped to a higher class.



I do not feel that reducing the weight of the car 1.5% is worth the bump in class.

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[SANDOVAL]

The real question is... is at a dampner or ballast? Just kidding... This is a topic like "Which tires are best" that seem to get everyone heated in debate. I say rip it out and store it case you ever sell.

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[sayporsha]

I took mine out & noticed a difference - the rear of car shimmies & shakes a little more, especially at freeway speeds. I don't like it & am going to put the damper back in.



I wonder if adding a crossbar or roll bar to tie together the upper shoulder belt anchor points eliminates the need for this inelegant lump of steel. Has anyone noticed an improvement in chassis stiffness by doing this?

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[rustech]

I love neutrality in nature. Unbiased posts are the best.

From my personal experience, when I removed it and the spare/tools, my car got extremely tail happy. I've had to correct this by widening the rear stance (increased front to rear bias) as well as the width of the tires. Now the car is more flickable and handles much better without all the extra weight. By reducing the weight in the rear, it has in a sense increased the effective spring rate, allowing me to bump up the front. The only thing I've noticed is a "stiffer" ride for this reason.

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[flash]

sayporsche - the short answer is yes - at least with my roll bar - i have ZERO shake now - extremely solid

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[968 Cab]

Removed the 48 lb TMD, relocated all the stereo amp, 10 disc changer and installed a 8" Bazooka sub in place of the 10" monstrosity the sterio installers put in there (and cut a 10" hole in the trunk carpet BTW thereby ruining it!!). New carpet ($433 OEM via Sunset Porsche - thanks!) makes the trunk look the way it should!



So no spare, but kept the tool roll in the trunk.



SoP (seat of the pants) impressions - absolutely no wierd gyrations, noises, etc with the TMD out. No cowl shake - top up or down, nothing out of the ordinary. I drove the regular roads for about 25 miles with some highway sections and huge bridge expansion joints but will head out to some twisty mountain highway sections today to check it out more thoroughly. As I stated before, this is NOT my track car, other than parade laps. The car drives with a little more light feel / liveliness - somewhat like when I take all the stuff out of my 951S and take it to a track.

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[flash]

and that has been much like our impressions too - any extra shake or anything took some really close focus to discern and really only popped up on a bumpy section (the dash wiggled a bit more) - it can be a bit tail happy at the limits too and will power oversteer a bit more easily



none of this is unmanageable and the extra fun more than offset it for those of us out here



with the roll bar, it's just plain fun



enjoy

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[968 Cab]

Thanks to all - this is a very good forum for these somewhat rare cars. With the collective tech knowledge, we can keep these away from the scrap heap!!



I'm definitely keeping the TMD - will not sell or dispose of it, and if I ever encounter any adverse effects, it will go right back in there.

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[flash]

get yourself a supply of ice packs and band aids - i've dropped that thing on my foot way too many times now - can't seem to find a spot where i don't have to move it

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[968 Cab]

[quote name='flash' date='Jun 15 2005, 04:43 PM']get yourself a supply of ice packs and band aids - i've dropped that thing on my foot way too many times now - can't seem to find a spot where i don't have to move it

[right][post="5916"]<{POST_SNAPBACK}>[/post][/right][/quote]



WHAT!! You mean I can't leave it on the upper flat shelf above the doorway?!?!!?!?? <img src="/forum/images/smilies/968/laugh.gif" class="smilie" alt="" />



That thing does tend to roll around on it's own. Right now I have it sitting on the step on the B&D Workmate...

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[chris]

Auto makers (even porsche) debate even the smallest part of cars since every small part taken out, or changed for something cheaper extrapolates to lower costs over the whole car line.



I find it hard to belive that they would put this "TMD" in the trunk for no reason at all.



hrug: I dunno, just doesn't make sense to me.

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[rustech]

Chris, and that's exactly why this topic has been discussed so many times.



In my case: since I removed it, and the car was power oversteering out of every turn because the car had lost it's balance and handling, what would be the cheapest way of correcting this?



In my situation: After removing the heavy thing, the spare, tools, et al, I've had to do alot to get the balance and drivability back in way of suspension upgrades, and wheel upgrades (bias difference front to rear). Now it handles much better than originally with the higher effective spring rate due to weight loss (which does make the ride a bit harsher) and matched it in the front.



My opinion is: How can they market a balanced car, when the Cabriolet front weighs so much more than the rear?

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[flash]

very true - many fail to remember that the hardtop car is actually 66 lbs heavy in the rear - removing the hatchback and sheetmetal lightened the rear up - adding the rocker panel reinforcement, the extra floorpans, and the windshield reinforcement (the windshields are not the same either - the cab one is 60mm shorter) further exacerbated the weight shift to the front - the extra weight was necessary to get back to balance



eric is exactly right on how much work it takes to get it right - i've pulled even more weight out and as a result have had to do even more to get it right - i'm only now getting close

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[rustech]

[quote name='flash' date='Jun 16 2005, 11:13 AM']very true - many fail to remember that the hardtop car is actually 66 lbs heavy in the rear - removing the hatchback and sheetmetal lightened the rear up - adding the rocker panel reinforcement, the extra floorpans, and the windshield reinforcement (the windshields are not the same either - the cab one is 60mm shorter) further exacerbated the weight shift to the front - the extra weight was necessary to get back to balance



eric is exactly right on how much work it takes to get it right - i've pulled even more weight out and as a result have had to do even more to get it right - i'm only now getting close

[right][post="5962"]<{POST_SNAPBACK}>[/post][/right][/quote]



The Coupe is 66lbs heavier in the rear than:

a. the front? or

b. the Cab rear?



What were all those stats again?

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[flash]

the unladen hatchback model is 66 lbs heavier in the rear than it is in the front - i can't find unladen distribution specs for the cab yet - i can only find gross vehicle distribution - if you use that though and then subtract the 397 max load capacity, you end up with the cab being 44 lbs heavy in the front

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[rustech]

[quote name='flash' date='Jun 16 2005, 02:06 PM']you end up with the cab being 44 lbs heavy in the front

[right][post="5973"]<{POST_SNAPBACK}>[/post][/right][/quote]

...and that's before the heavy thing, spare...are removed, right?

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[flash]

those are all factory delivered numbers (stock)

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[ds968]

um, I removed my spare tire ( 28 lbs ? ) and did not notice any change, but then again we're talking about someone ( me ) who did not notice any change after installing a KLA strut tower bar either <img src="/forum/images/smilies/968/blink.gif" class="smilie" alt="" /> , while others claim it's like day and night when cornering.. so may be the negligible shift in weight balance caused by less than 30 lbs is not very significant to my type of driving

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