First DE approaching - Tech questions

[Tom '74 911]

Hi -
I've got my first DE in a few weekends, I'm very excited, and I've got some easy tech questions. I'm driving 5 hrs to the track - I live in the middle of nowhere - so I don't want to get all the way there, only to fail tech and not be able to drive! I am leaving a day early so I can get my car aligned at a recommended shop "in the big city" - they will also do the tech for me. I want to be as prepared as possible, and am also using this as an excuse to do some general maintence etc... on my car. I've been getting advise and help from fellow Pelican "jaydubya" as well - thanks Jeff!

My questions are about:
Aluminum lug nuts - are they OK?
Tires - mine are mismatched front to back. Fronts are Michelin Pilot XGT Z4, rears are Cooper Cobra GTH. Tread is fine, but is mismatch OK and I don't know if the Cooper's speed rating is the same as the Michelin's?

Keep in mind that this is my FIRST DE, and I'm just looking to be safe here, not trying to qualify for "the big one". My car is getting an oil/filter change and new brakes at all 4 corners, along w/brake fluid flush - among other things - so it's not neglected by any stretch.

Is there anything else I should be checking? I've got the Tech Insp. List and am comfortable w/everything on it - what am I forgetting?

Thanks for the help,
Tom

[Don Plumley]

It really depends on who is the racing group. Some are very picky, some are not. In general, for a DE as long as the car is street legal and well-maintained, it should be fine. Alu lug nuts are fine for a DE (well, maybe some PCA regions might not like it). Steering and brakes are the big ones, oil fresh and full (just over 1/2).

Your tires concern me a bit. If you are just learning, and the speed rating is proper, then it's probably okay. Go into your garage and look at the speed ratings...

Have your shop check wheel bearings for play, CV boots and bolts, throttle return spring, and steering play. Make sure the aligment shop has done Porsches.

Have Fun!

[emcon5]

Originally posted by Tom '74 911

Tires - mine are mismatched front to back. Fronts are Michelin Pilot XGT Z4, rears are Cooper Cobra GTH. Tread is fine, but is mismatch OK and I don't know if the Cooper's speed rating is the same as the Michelin's?

I believe the Michelins are "Z" rated, which is fine. I don't see Cobra GTH on Cooper's web site, but a few other references to it on the web indicate they are "H" rated, which is good for 130 MPH.

Verify this by checking the tires, the speed rating should be marked on the sidewall.

It seems to me like that is a pretty big mismatch. Are they even the same class of tire?

Tom

[DanS911]

The tires concern me too.
I am not familiar with the Cooper tires but one of the concerns in having mis-matched tires is that one end may be way sticker than the other end. Or heat up differently. Not an ideal situation, should pass tech though.

[mede8er]

Oops...already doing it.....

[Dixie]

Aluminum lug nuts - are they OK?

Yes

Tires - mine are mismatched front to back. Fronts are Michelin Pilot XGT Z4, rears are Cooper Cobra GTH. Tread is fine, ...

No problem as far as this PCA National Instructor is concerned. I doubt you'll be running 10/10th your first event.

Is there anything else I should be checking?

Make sure you have fresh, good brake fluid. Something akin to ATE Super Blue. Also make sure you have at least 50% of your pads. My student today only made it to noon. Why? He showed up with way too little rear pad. By noon we were down to the backing plates.

Otherwise, my best advice is, Relax....

[Tom '74 911]

Thanks for all the comments. As far as I can tell, the speed rating on the Cooper's is "H" - which is 130 mph. I realize the mis-match isn't optimum, but it's what came w/the car when I got it at the end of last summer. There's plenty of wear left, and as long as it's safe for a conservative first-timer, I'd like to run what I've got before throwing down (more!) money. I'll get a matched set when what I've got wears thin.

I am putting on (4) new rotors - as they are all measure below 18mm, as well as new pads all around, followed by a brake fluid flush - from ATE blue to gold. It's a good excuse to do some maintainance and a good once over etc...

I'm excited about the alignment too! I've been running on a home alignment since last fall, which seems good, but I will have more confidence in it after being verified by a "pro".

Thanks for the advice,
Tom

[nostatic]

How old are the tires? I'd be less worried about the mismatch and more worried if the rubber is quite a few years old. Doesn't matter how much tread is left...if the sidwall is cracking, etc, it isn't good.

You might want to check your battery to make sure it is held in place, and that the terminals are covered.

[Noney]

You mention you're getting new brakes. Are you getting them before you leave for the event, or is the shop that's doing your tech inspection putting them on? Either way, make sure you leave yourself enough time/distance to bed in your new pads and rotors before you hit the track for the first time. It could be an eye-opener, to say the least, to get out on the track for the first time and have your brakes perform in an entirely unfamiliar way.

As Capt. Carrera says, just relax, be smooth, listen to your instructor and have fun out there!

[efhughes3]

All I can offer here is that it will be a little tougher trying to learn on tires that may be mediocre. I had really cheap Yokos on my car when I got it, and it was like night and day at the track when I put S03's on.

[Tom '74 911]

Thanks for all the sage advice so far. My brake rotors and pads should be arriving tomorrow or tues. and I'll get them installed by the end of the week - I'm doing all the work. That'll give me the entire next week to brake them in (no pun intended), not to mention the 5 hr. drive to the track! I'm hoping to have enough shake down time after working on the car to get all the bugs out - yea right!

My goals for this first day are:
Safety - I'm driving my car to the track and want to drive it home too!
Learn more about my car in a (more) controled and safer environment
Have fun!

Pretty basic. I have no lofty goals at the moment. I'm just hoping to get a feel for the whole DE thing and see if it's something I want to do again. I'm really excited to drive around w/an instructor. I hope to learn a lot and expect to return at the end of Sept. for a PCA race weekend to get some more time and instruction.

We'll see how it goes. The closest track to me is quite a ways away - maybe that's fortunate - or else I'd be there more often.

Tom

[304065]

DE is difficult enough without having to contend with the handling quirks caused by different tread patterns and compounds front and rear. I would invest in a good matched set of treaded track tires like Kumhos.

[Wil Ferch]

Kuhmo MX's are the ticket...and not expensive, either...

Other hints:
- do all your braking in a straight line....before "turn-in"
- brake "backwards"....try to get on the binders fairly "hard" ( at first) and learn to ease off ever-so-slightly in your braking zone...before turn-in. Most novices ( actually "most" people) brake the opposite. They slide-on the brakes gently and progressively brake harder just before the turn-in point. Two bad things happen when you do this:
1.) you drive a lot of extra heat into the brakes....
2.) The nose is driven "down" at the end of your braking zone and then "pops" up before your turn. Much better the other way around ( "braking backwards"...hard at first progressivley letting up)...so the nose doesn't bob up before you turn.

Oh yeah.... use a late apex...not an early apex. This gives you enough room when you "track-out" exiting a turn, and you won't overdrive the car or be forced off the opposite side of the track as you complete your turning....

Your instructor will tell you all about this...but you may want to print this out and emphasize this to him too.... good luck and have fun.

- Wil

[TD in DC]

Wil,

I agree with your braking advice, but I always understood the terminology to be exactly the contrary. In other words, I always thought the phrase "braking backwards" referred to the bad practice of braking lightly at the beginning of a braking zone and steadily increasing the pressure until the end of the braking zone.

As you correctly point out, good braking technique involves loading the brakes gently (i.e., not slamming on the brakes) followed by going to maximum braking pressure immediately with pressure released gently at the end of the braking zone.

[Wil Ferch]

The "terminology"...I guess...can cut both ways....

It was presented to me that people "brake backwards" as novices and should do the opposite. Of course, maybe the terminolgy is not to do what comes natural...but to "brake backwards".....

..as long as the desrciption of what to do correctly is done...that's all that matters....

- Wil

[TD in DC]

Originally posted by Wil Ferch
It was presented to me that people "brake backwards" as novices and should do the opposite.

Yes, that is my understanding of the use of the term. Nearly all novices "brake backwards" when they start doing DEs because they gradually build up to full braking pressure at the end of the brake zone. That is why many instructors say: "do not brake backwards."

In any event, so long as people get the right idea, it is less important what you call it.

[mrbill_ftl]

this braking backwards concept...... some questions....

its brake hard then coast/ease on brakes.. to turn in point.... is this a new idea?


I was taught by skippy, on a 1 to 10 scale (ten is lockup), stay on the gas, until the brake zone starts... no coasting... then a 2-3 peddle to settle the car/ nose, tranfer weight, and get all pads touching rotors.... then go progressively to a 4,5,6,7,8,9 right up to lock up... then turn in...

in the classroom they showed a slow motion video of threshold braking, in a formula car... looks kinda like a stop watch second hand, tires moves and stops, like a tick tick.. about 6-8 times a rotation.

also went into slip angles, contact patch, brakes vs tires, and of course not to transmission brake. by coasting into the turn in, its harder not downshift early... imho.

of course the skip barber program was a RACE school, is the braking backwards better for DE

[tonythetarga]

"I was taught by skippy, on a 1 to 10 scale (ten is lockup), stay on the gas, until the brake zone starts... no coasting... then a 2-3 peddle to settle the car/ nose, tranfer weight, and get all pads touching rotors.... then go progressively to a 4,5,6,7,8,9 right up to lock up... then turn in...

Using the same scale, I would say it is more like 5-6 then jump to 8-9-9-8-7-6-5-4-3... plus or minus whether you do any trail braking into the corner.
The "backwards braking" is the reverse of what we normally do on the street. I use the term counter intuitive, as you have to un-learn street techniques and learn new track techniques.
I would say the DE braking method and the race method are pretty much the same. The only difference is DE teaches safe high speed driving with optimal lines, braking and turn in while racing starts out with that as a core and then evolves into winning, by, as many would say, taking measured risks that may or may not work to gain every/any advantage.
Just watch a pro race at any track you have driven on and you will see the racing line barely resembles the DE optimal line.

[MrBill_fll]

yeah, ok, thats what I though, and (sorry). I'm still not convinced.

(I flagged 10 yrs, raced 5, and inst 5 yrs)

Problem I have with the 5-6 inital peddle pressure if the rotors are warped, I'd be off track trying to settle the car. ("hunting side to side under braking")

-sounds a lot like trail braking, before the turn in.


if its a teaching technique, ok, but if this is the fast technique, I'll need more convincing...

its there an AIM or data aquisition data to back this stuff up?

(probaly need a new thread on this, eh?, or should I do the search....)

[happe]

If he's out there, find Aaron Pfadt.(pfadtracing.com) He's the best instructor out there..Look for the Air Power Rig and ask.
You will not believe how well your car behaves.....Your going to have a blast...
Matt
Matt@revolutionutah.com