mcipseric

Hi everyone,

I was wondering if there was any validity to thought that the spare tire was part of the structural front end crash protection built-in by Porsche on our 993s?
I always remove the spare tire when auto-crossing.
I am concerned with the safety factor while driving DEs and TTs. If the spare tire is necessary for safety, then I would have to corner balance with the spare in the car. Obviously, I'd like to leave the weight out, but not at the expense of safety.

Thank you.

Mark in Baltimore

I leave my spare tire in for the crash protection. I have zero data, but that extra rubber and aluminum have to provide extra energy absorption. I have to make weight anyway, so why not? BTW, I don't think the tire weighs enough to make any significant difference in corner balancing.

Martin S.

I too need to make weight, the spare weighs 30 Lbs. My car needs to weigh 3205 in Impound Pots race. I was a little light, so back went the spare. I also need to have a full tank of gas in the car prior to a race...burn up at least a quarter tank in 30 minutes of racing.

Having some extra weight down low and up front is not so bad.

d ward

I've always wondered the same, as run with out the spare wheel.
I was of the opinion that the front of these cars are very well built and by removing the spare wheel the wheel well becomes a extra crumple area, as with the spare wheel in place & the fact that the wheel is effectively two arches put together so despite being only alloy is still very strong and may not crumple and just transfer the impact further back towards the passenger cell, where as with out the spare wheel in place you have a void for the metal to crumple into.

Just my opinion of course and I may be completely wrong.
although I rather hope I need never put it to the test, spare wheel or no spare wheel

Mark in Baltimore

I wonder if Porsche removed the spare tire for DOT crash testing? I'm guessing they did not since the car probably had to be tested as-delivered to the consumer. Just a guess, though.

d ward

Yes you are correct, if it came to the customer with a spare wheel, it would be crash tested as such, at least in european countries, I dont know about other countries. Thats not to say it makes the car safer, its just the car has a spare, it has to be put somewhere and the 911 is a small car and it is crash tested with that spare in place as a requirement of the crash test.
Im sure porsche gave thought to the safety aspect, but that said I'm sure they would have preferred not to have to put the spare in, as 911s of the last few years have no spare wheel at all.
The only thing I would say and its nothing but my observation, is than ive seen a lot of cars hit in the rear (the normal place for the spare wheel to be kept) and always the cars with the spare wheel in place, have the damage carried through closer to the passenger cell and the spare wheel once you cut away the mangled metal is more often than not barely damage if at all, which suggests to me the spare wheel merely transfers the impact across the spare wheel well and further into the car.

Matt Lane

I know someone who is going to be happy when he reads this...

cgfen

so your are saying that removing the spare makes the drivers cell area less likely to be mangled in a front end collision????

Craig

Ed Hughes

I would think that if it were an integral part of the design, the lawyers would've had Porsche plaster the area with warning stickers.

KaiB

You may have a really valid point here.

Despite years of conjecture on forums, I have yet to see absolute proof one way or the other.

race911

How many of us have seen all manner of headers over the years? I don't think it makes a damned bit of difference through the survivability range. I bought one wreck ~20 years ago that went nose first into a wall at probably 20MPH, no safety equipment, spare removed (was running stock class), and there was no way we were rebuilding it. Similar, a few years earlier, one of my customers wrecked a 2-3 month old 930, amazingly head first at about the same 20-25MPH, and we did put a new front clip on it. But the body guy regretted ever touching the car. It jigged up square, and I aligned it fine, but the bill was $30K+ in 1986 dollars. No one made money on that one............

k722070

I can just see the warning label-DO NOT USE THIS SPARE TIRE AS A SPARE TIRE
and imagine the lawsuits if a 911 was in a head on collision while using the spare tire...

budge96

Believe me you want that aluminum spare in there when it does happen! Took a header at speed on a
granite curb in the wet and the curb all but stripped the chassis of suspension but while still moving at
an alarming rate say 45/50 the curb acted as a rail and directed the car into a fire hydrant ..which
luckily was of the breakaway variety but still simply crushed the aluminum reinforcement and proceded
to place a perfect U in the spare! Once it had anialated the steering box of course!
that slowed us down and how! no one had as much as a scratch can't say the same for the tub and of
course that spare was toast! Bert
oh this was ten years ago...

993C4RS

You should rig up your stock steering wheel in place of the spare, then when the airbag goes off it will help cushion the crash..

d ward

Hi Craig, yes I would of thought that by removing the spare wheel it would help to prevent the passenger cell getting as mangled, but that's only my opinion.
Was explained to me by a body guy like this, if you place a empty coke can on the floor & stamp on it,the metal crushes easily into the void inside the can & very little of the energy is transferred to the floor.
Then fill another coke can with stones & stamp on it, this time the metal of the can has no void to fold into and most of the energy is thus transferred through the can & into the ground.
So by removing the spare wheel their is more space for the metal work of the car to fold into in a crash thus assorbing some of the energy of a crash.