[Cloud9...68]

[quote name='flash' post='43622' date='Nov 15 2007, 09:26 PM']the bumpers are only good for speeds UP to 5mph - after that, they actually cause more damage[/quote]

Yes, I believe this is correct. I remember back in '73 when "5 mph bumpers" were first legislated, and, as their name implies, they were really only good up to 5 mph. I know many of the designs since then have improved to the point where they can offer protection at speeds somewhat north of 5 mph, but not by a whole lot. After that, the repairs actually get more costly than if the bumper wasn't there.

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[pazzer]

Well got all of the carpets out and most of the foam and the grand total of 23kg's, at this rate i'm well on my way to reach my target of getting rid of 100kg's, that means i can still eat my pies, ha ha ha.... regards pazzer.

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[Big Dave]

Na,,, Chris.. You still need to go on a diet...."pie-eater"... <img src="/forum/images/smilies/968/biggrin.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/biggrin.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/biggrin.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/biggrin.gif" class="smilie" alt="" />



OR



Maybee get eating some more pies.. That way "we" will be able to keep up with you... <img src="/forum/images/smilies/968/biggrin.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/biggrin.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/biggrin.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/biggrin.gif" class="smilie" alt="" />

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[frogisland]

Don't worry Dave, will take him plenty of fish and chips around.....and a few crafty lead weights in his sills.



Was quite surprised at the weight loss, c18.5kg from the carpets and foam alone, the shelf was a further 6kg and the rear hatch area removable carpet must be nearly that again. Coupled with all the glue, some of the interior panels and there must be 32/33kg coming out.



As for the bumper, trust me, i know from experience that they are very effective at spreading the load across the front/rear of the car without necessarily 'pulling' the two sides together. The compression tube appears to continue working at higher speed than 5mph and saved substantial impact damage to my chassis. My concern would be that without the bumper bar much more of the force of impact would be transmitted directly through the chassis legs, resulting in greater damage, and possibly writing a car off.



As to whether the bumper bars stay on or come off, i think the weight saving is justified. Dave and i have seen our fair share of 'offs' at the track - both trackdays and watching racing - due to the speeds involved (and plenty of wet grass) they nearly always result in substantial damage, quite often to more than one corner/side, and i doubt that the bars would lessen the damage to the car much. ....might be a saving grace to what injury you pick up though.



It is good to see pazzer has the courage to go this step further, in some respects manyof want to do it, but fall back to a compromise position. It has surprised me at how much everything weighs. can't wait to see how it changes the dynamics of his car.



As pazzer and myslef have mentioned, Porsche could have made a fantastic CS at little expense - much lighter carpet/interior and more easily removed, small amount of seam welding, no options (i.e. sunroof hence resulting in minimal loom) etc etc.



JP

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[PJS917]

Having had two cars drive into the back of mine, I would leave the bumper bars in place, or

fabricate a lighter bar to spread the load. As you say JP the compression tubes are what saves the chassis and I would not want an accident without them.



As for next year, I will be the one at the back <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" /> but I will be the most comfortable too and from the tracks? I will also eat the pies safe in the knowledge I can blame the car for the weight <img src="/forum/images/smilies/968/laugh.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/laugh.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/laugh.gif" class="smilie" alt="" />



Pazzer, let me have a list of bits you are removing, I am after a CS rear shelf and carpet delete, if you have em, I'll buy em of you, providing you spend it on pies, beer and chips........ I am going to need all the help I can get.

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[333pg333]

We found that we could substitute a ride on lawn mower battery for race day and that saved plenty of lbs.

I thought that the term 5mph bumpers was due to the legislation that happened during the '80s in the US and that's when they designed those bumpers that were on the 911 of the time that had the black rippled rubber appearance? I'm interested in Flash's comments about our bumpers being of no real use. If that's the case that would open up quite some space, especially if you have a large front mount i/c, but even opening up the cooling passages to the a/c and radiator would be beneficial apart from any weight savings.

Paz, you should try and get a lexan rear hatch replacement (not easy outside of the US) and a c/f hood. I got my hood and 968 rear spoiler with c/f centre piece from http://www.v-zweeden.com/ I haven't got around to installing them yet for a few reasons, however they do present some great savings in lbs...but NOT to your bank balance! The product is not 1st class but can be finished off when you get it. Some other body parts for 968's too. Worth checking out at least.

What's happening with your engine rebuild too? Not sure if you saw my reply on your post?

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[pazzer]

Hey pat i saw your reply, i never miss one, as for the engine side of things i still humming and rrrring, as i have only done one track day in my life i have thought about doing as much to the car as possible myself without costing big£'s eg removing all interior, AC and heater power steering etc and running the car for a year on track, just to get some experience behind me, its hard for me because without sounding like a spoilt brat, which i have not been, i have always got to have the best i can afford, and i want this 968 to be awesome, it will never be a minter concourse car but it looks well but needs more power, you never know i might just get a blower slapped on 350bhp and 1150kg should be a big improvement over what it is know, if the engine blows for some reason then get it rebuilt, i have about 12-15k at my disposal, what would you doin my position , paz <img src="/forum/images/smilies/968/cool.gif" class="smilie" alt="" />

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[flash]

there are a couple of guys here who can easily attest to the damage CAUSED by the bumper - the initial impact was one front corner, and should have been limited to that corner - however, the bumper transferred the impact to the other side, thereby bending both sub-frame rails



in a uni-body car, this is bad - there is no continuous frame, so there is no reference point to which to straighten things - that makes the car a total loss when this happens



in the front of the car, this is a lot more common of a problem than in the rear - most rear impacts are straight on

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[333pg333]

Wow that's very interesting Bob. I've never heard any mention of it and I guess it makes basic common sense. What about absorbing front on collisions though? You would think that it has it's usefullness too. Might it not protect the engine and possibly the driver in a big front on crash?



Paz, well I think by just adding some lightness for the first real season is a good idea and it may give you more time to figure out what you really want plus save some more money. If you then go ahead and build a monster motor you will need to upgrade other parts and that will of course have to be factored into your overall budget. You will be able to benefit from my build if you do decide to do a monster. I will have sorted out any teething problems and developed some new and unique parts for our cars in the next 6 months to a year. Depending on when it's done and when we can install it. It's being designed and built now but we have to wait for some totally custom made parts from offshore to be completed. A year ago I jumped into modifying my car and it has been one disaster after another due to bad luck, bad timing, bad management etc So don't jump into the same problems. Speak to those that have gone before you and benefit from their experiences. Everyone will help I'm sure.

Patrick

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[flash]

the concept of rigid structures being helpful is a carryover from days of old when we drove huge lumbering behemoths - crumpling is what absorbs impact energy, thereby protecting the occupants - the tradeoff is damage to more areas of the car



it's basic physics really - simple application of newton's laws and kinetic energy - it has to go somewhere, the car or the occupants



as an extreme example, take a look at formula cars - they disintegrate on impact, taking with it the energy of the impact, but protecting the driver - not a bumper in sight



frankly, if the impact is big enough to have to worry about the car being totaled, the more important issue of occupant safety is being overlooked



if you want to save the car, then by all means add rigid structuring all over it - you may have to admire it from a wheelchair though, assuming you are lucky enough to survive the crash



as for engine stuff, i agree - set up the chassis first - power is last - it's amazing how different these cars are when they are lighter and have a real suspension

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[pazzer]

Well the chassis and brakes are allready at the best i think for what i need heres a breakdown of my car.



1. mo30 clubsport shell no sunroof.



2. 993 big reds front, mo30 rears, pagid yellow rs29 and 19's. braided hoses.



3. bilstein escort cups running 800lb rears, 700lb fronts.



4. kokeln rear delete kit.



5. racers edge solid bushes throughout.



6. rs barn headers and cat delete system, but needs modifiying to reduce noise level to 98db, currently 109db.



7. rs barn chip to suit. plus airbox mod with k and n filter.



8. flashes top strut brace and lower brace.



9. racers edge camber plates.



10. kokeln a-arms.



11. new mo30 sways front and rear, with spherical drop links.



12. half rear cage.



13. shroth gt3 6 point harnesses.



14. recaro seats, originals from car.



15. 18 inch carrera lightweight rims



so as you can see from the list the car is pretty much sorted for trackdays, just thinking of more power, but with losing 100 kg it should be more responsive anyhow. the last time the car was coner weighted i think it weighed 1250kg so in theory, with the lights replaced with smaller and lighter units, interior, pas, ac, and heater removed i'm hoping to be down to 1150kg, well it should all be done by feb so i will let you all know, no work on it in december as its chaos in my work place, food distibution you never seen so much at this time of year, dont know where it all goes and its not cheap food either "MARKS AND SPENCER" so iwill crack on in Jan, regards chris. <img src="/forum/images/smilies/968/cool.gif" class="smilie" alt="" />

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[sguy]

I finally removed all the weight off my car I can possibly find. There is nothing left but frame, a little fiberglass, suspension, wheels, engine, and transmission - although they fit better in the rear after all (see attached). I guess the only thing to do with the car is go racing next year? <img src="/forum/images/smilies/968/tongue.gif" class="smilie" alt="" />



       

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[Eric_K]

That looks fun! It looks so small - can a human actually sit in it? <img src="/forum/images/smilies/968/tongue.gif" class="smilie" alt="" />

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[pazzer]

get those stickers off must be at least a couple of grams, ha ha ha, should be fun and feel a lot faster than you are actually going, very nice indeed. <img src="/forum/images/smilies/968/cool.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/cool.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/cool.gif" class="smilie" alt="" />

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[PJS917]

[quote name='pazzer' post='43767' date='Nov 19 2007, 04:58 PM']food distibution you never seen so much at this time of year, dont know where it all goes and its not cheap food either "MARKS AND SPENCER" )[/quote]





Thats not just food Distribution, It Is Marks and Spencers food Distribution... <img src="/forum/images/smilies/968/cool.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/cool.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/cool.gif" class="smilie" alt="" />

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[pazzer]

cheers dude , by the way would you know of anyone who could maintain a service contract on my recently aquired lear jet, just a few feelers befor it goes out to tender, cheers pazzer. <img src="/forum/images/smilies/968/laugh.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/laugh.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/laugh.gif" class="smilie" alt="" /> p.s all interior is removed for keeping up with those pesky migs. <img src="/forum/images/smilies/968/cool.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/cool.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/cool.gif" class="smilie" alt="" />

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[333pg333]

[quote name='flash' post='43762' date='Nov 19 2007, 09:12 AM']the concept of rigid structures being helpful is a carryover from days of old when we drove huge lumbering behemoths - crumpling is what absorbs impact energy, thereby protecting the occupants - the tradeoff is damage to more areas of the car



it's basic physics really - simple application of newton's laws and kinetic energy - it has to go somewhere, the car or the occupants



as an extreme example, take a look at formula cars - they disintegrate on impact, taking with it the energy of the impact, but protecting the driver - not a bumper in sight



frankly, if the impact is big enough to have to worry about the car being totaled, the more important issue of occupant safety is being overlooked



if you want to save the car, then by all means add rigid structuring all over it - you may have to admire it from a wheelchair though, assuming you are lucky enough to survive the crash



as for engine stuff, i agree - set up the chassis first - power is last - it's amazing how different these cars are when they are lighter and have a real suspension[/quote]

I guess the concept being if you had a big front on crash without a bumper, could that not increase the chances of becoming a mid engined car than with a bumper? Do you know of many racers who have deleted their front bumpers. No names are needed. Anonymity is guaranteed.

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[flash]

in other cars, yes, plenty



as for the engine ending up in the middle, it would have to collapse the torque tube to do that - not likely

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[333pg333]

Paz, that must shake your fillings out of your mouth with those Escorts with the spring rates and solid bushings?!? In general though it should be a pretty quick little car. The Kokeln rear delete is meant to be pretty trick but is it heavier or lighter than stock?

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[pazzer]

The Kokeln rear delete kit is way way lighter than the stock torsion tube, around 12kg lighter.

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