TB993tt

Not sure if this topic has been discussed before, but couldn't find anything with search.
Like many of you I'm sure I run without a spare, tools and jack to take advange of the 20kg saving. I've always wondered if this affects the safety of the car in a front end crash ?
With the location and orientation of the spare, it must absorb quite a lot of energy in a frontal impact and presumably Porsche carried out all its crash tests with spare in situ. Does anyone know anything about this issue, have any racers had front end smashes -how did the crumple zones perform without the spare ?

Singh

I thought about doing this too - but wondered whether handling characteristics would be materially different taking more weight out of the front - does this mean even more weight bias towards the rear end of the car?

STLPCA

[quote]Originally posted by TB993tt:
<strong>Not sure if this topic has been discussed before, ...</strong><hr></blockquote>

Discussed, but never resolved ...

<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=3&t=001388" target="_blank">Spare tire - part of crush design? </a>

I posed the question to the PCA Tech gurus and received an email that basically said they don't know the answer, but it can't hurt to leave it in.

From a handling perspective, I would think having the added weight in the front on a stock 993 is good.

os993

I leave everything in when I'm tracking. I see lots of folks removing their spare prior to hitting the track, but as Singh and Dan point out, I also believe the spare weight in the front makes my car handle better (more neutral).

As for crash protection, definitely can't hurt to have everything in place. Plus, I've already had one flat (daily driver), so logically doesn't make sense to yank out the spare.

Cheerio!

Jim Michaels

I'm with the add weight to the front end crowd. We give up a little acceleration to gain noticable handling. If the spare were in the back, I'd want to pull it. I also run nearly a full tank at autox, but I've heard of a guy who also throws a big sack of sugar in the front.

Yes, I do think the spare is considered part of the crush zone. I do know that at least one DE participant was chided by the tech inspector at the track for not leaving his in.

Singh

For weight watchers - the rear "seat backs" weigh a bit and are easy to remove and reinstall. This weight is at the "right" end of the car to lose as well.

Flying Finn

Guys,

While I agree, that removing weight from the front isn't the first (or best) place to do it on Porsche, it still is removing weight.

And any weight you remove from your car (or from yourself! ) is good, while gaining little more acceleration (which in this case is really marginal) is of course good but even better is better braking (and handling, even when reduced from front). Lighter = faster! <img src="graemlins/burnout.gif" border="0" alt="[burnout]" />

Do a test: remove spare (or keep the spare), then play with fuel load, you propably can feel if/what difference it'll make.

And like Singh said, back seats must go too!

Kevin

I have seen my share of 964's & 993's in the Northwest that have sustained front end damage (can't stop on wet surfaces). The spare tire has absorbed alot of the energy that would have been transferred further back into the structure. Yes, the frame rails are designed for this purpose, but there are certain hits that would centered into the center of the car.

Speedraser

I haven't read anything specific to the 993 (or 964), but I do recall reading in one of the big Porsche books (Ludvigsen? Frere? -- I don't remember which) that the only change Porsche had to make when it crash-tested the 911 (901) for the US market (around '68) involved the spare wheel. I don't know whether removing it would make matters better or worse, but it should be very safe (no pun intended) to assume that it was considered in the design. I recently saw a 993 that had a heavy front-end crash. The spare wheel was virtually folded in half. I can't say how much energy it absorbed, but it certainly did contribute something. BTW, the driver was not injured. Personally, I leave the spare in place.

996FLT6

Let's just say you lightened the rear like a lighter exhaust that saves like 24-29 lbs. Now wouldn't it be equal to lighten the front ie removing spare so basically the main charateristics in the car ie handling is the same? I probably agree that it would help with frontal collisions so I normally leave it on when I'm not tracking. I welcome other people's comments on this. Regards. Mike

Edward

As others, I don't know for certain with Porsches. But I know that with the "boxer-engined" Subarus the spare, also at the front, is a designed-in safety feature for frontal collisions. Apples and oranges, I don't know, but I've always left mine in for all that reason alone.

Edward

TB993tt

Quiet Sunday so I got my corner weight scales out.
Car weighs exactly 1500kg with 3/4 tank, without spare + tools with a split 38.7% front, 61.2% rear. With tools + spare + jack 1517kg 39.6%/60.3%. With a car this heavy the 17 kg seems of little significance to the balance of the car. In terms of extra performance, running without the extra weight is worth 5hp- less than 1% increase for this car.
I am quite concerned about the need for the impact absorbtion of the spare that some of you have pointed out so I am going to bolt the spare back in situ but without tools or jack: 1513kg -39.4%/60.5% and loss of 3.65hp.
Like I said -quiet Sunday <img src="graemlins/wave.gif" border="0" alt="[byebye]" />

E. J. - 993 Alumni

I know it's not the same, but if you've ever looked in the trunk of a 996, you will see that the spare tire sits upright against the fuel tank, - not across the floor like in our cars.

Here is a pic of 996 I saw at the body shop a few years ago - it was eventually totaled, but the insurance originally wanted to fix it.

<a href="http://p-car.com/booboo.html" target="_blank"></a>

E. J.

Speedraser

Why is it that cars that hit trees or poles head-on usually manage to do it dead-center? <img src="confused.gif" border="0">

Flying Finn

[quote]Originally posted by Speedraser:
<strong>Why is it that cars that hit trees or poles head-on usually manage to do it dead-center? </strong><hr></blockquote>

Careful driving! <img src="graemlins/roflmao.gif" border="0" alt="[hiha]" />