old man neri

No, as far as I understand it you will not gain patch size, just change the shape of it. Also, even if you did increase patch size you wouldn't get more grip. Theoretically grip is merely a function of both the force applied (how much your vehicle weighs) and the coefficient for friction, area is not used. That is of course a very basic formula but it still more or less explains it.

Again, I would find the right tire size for you and then the size of wheel you need for it. Ideally in the middle of the 'approved rim widths' given for that specific tire size/model/make.

This advice was given to me from a friend in the US who is a track *****, he was 30K mi on a track 15K of which is instructing. I listened to what he had to say.

Cheer Shannon!
-matt

Ed Hughes

For the record here, I just ran a new set of Porterfield R4-S pads today at Streets of Willow. They were great-we were in the 40's today-they had good bite at the very first turn. Wish I could say the same about my tires(!), they took 3 or 4 laps to come up to decent pressure.

But, this was a track that wasn't too awfully hard on brakes-I know Jeremy gives his a workout at Sebring.

justinsrx7

Just make sure that if you ever do this upgrade, it is done with all the corect components. Mine were upgraded at some point before I purchased my car. They are pretty crappy (pedal feel and stopping ability) and they squeal like an 18 wheeler on hard braking with rusted rotors.

My mechanic thinks I may not have a properly matched master cylender or brake booster (or booth). The only way to find out is to dismantle the system and check part numbers. An expensive but necessary proposition.

g-50cab

Up until a few days ago I was running 225/45/16 and 245/45/16 Hankook Rs2 for the street and 225/50/16 and 245/45/16 Toyo RA1's on 8" (951) Fuchs on the front and 9" fuchs on the rear.

You need an offset of + 23-29 mm front and 11-16 mm rear.

g-50cab

Did you have fun today Ed? Good to be back in the saddle?

DaveConn

Hey Shannon,

Sorry for the delay in responding. FWIW, there has been a lot of good advice posted so far (and again, some I would be careful of). In reading your responses, I get the impression you are inflicted with the track disease , but it is also apparent you have done a lot of homework...

In my case, I took a wholistic approach to the braking 'equation'. I have been working to shed as much weight as possible (yet still maintain a 'finished' appearance and some street comfort), and I am definitely concerned about unsprung weight (the DEVIL!). My goal was to not only increase thermal capacity, but also shorten stopping distances from speed, with primary focus on track duty.

I'm guessing you won't be surprised that, in addition to a LOT of reading on Rennlist, various books, etc., I sought the advice of Mr. Weiner when deciding the final 'kit of parts'. I have completely replaced the braking system in my car: new rotors, calipers, pads, lines, master cylinder, etc.

BTW, brake BALANCE is EXTREMELY important in anything you may do! In my case, for example, we did not alter the proportioning valve, but instead utilized a combination of Pagid pads to achieve a completely stable result under track conditions. IMHO, you might seek the advice of folks who have tweaked 911s of your vintage, once you decide on the direction you want to go.

Here's to winter projects!

Best regards,

Dave

rbuswell

Steve, I looked at your 930 kit on your website but didn't see how you price them even though you price some of your other aftermarket kits. Is it based on whether 930 calipers are in season or not?



Also is it possible to get the kit without the 23 MC. Grady suggested I put one in when my 19 went down last year, in anticipation of doing something like this in the future. Thanks.

Steve Weiner-Rennsport Systems

Contact me directly for pricing information and yes, it can be provided without the 23mm MC....

r911

It is crab season right now, but the 930 calipers will be in season soon.


BTW - a company is planning to make 930 or 930 look calipers/brakes - there is a long thread somewhere on Pelican.

911vet

Matt, you never steer me wrong. Thanks for the info. I am leaning towards OE 16x6 and 16x7. It appears I will have a somewhat limited number of R-compound tires to choose from regardless of what size I go with. But right now, the Toyo R1R/R888 and Michelins Sport Cups come in either size.

Heck, I can't outdrive the tires I've got, why am I worrying about this?!

911vet

I was very fearful of 911 throttle-off oversteer when I got this car. Not only was I afraid of spinning, but I was also unsure if I could "force" myself to keep the foot on the gas (or, eeeks, give it more gas) when I was heading into a corner too hot.

The track solved all that. It taught me, 1) this car can take corners fast, 2) the more gas you give it, the better it does, and 3) I can actually overcome the urge to lift off the throttle.

The best thing that happened to me on the track was a couple of tail wiggles. I caused the first by throttle-off... haven't made that mistake again! The second was one of those "whoa, where did that come from?" moments that felt like I was about to do a 180. I managed to save it - and I did it in a relaxed way.

The track isn't about "going fast" for me. It's about negotiating the curves. Ok, negotiating them fast.

I was a good driver to begin with. I'm a better one now. Will get better with more time.

Yep, I'm addicted.

I have lots more to do. Thanks for your help.


Thanks, Steve is Da Man!!

I run at Mid-Ohio, a track known for causing brake failures. I feel compelled to improve my brakes. Before I make any major mods, I'll change pads, upgrade the fluid, and install a cooling kit.

g-50cab

Smart -

And while Matt brings up a good point re: contact patch - by increasing the width of your tires - you change the shape of the contact patch. With the short comings of the 911 suspension - especially in more stock formats - using a wider tire moves that contact patch further outboard which can help with grip, even with lots or camber dialed in.

Mahler9th

930 calipers are getting to be like hen's teeth... and there is more than one way to fit them up on a 911. I don't 95% of the stuff Steve mentioned and mine work just fine. But my car is very light. Since there are a lot of approaches, it may be best to work with someone with experience like Steve who knows what works and what is needed. Years ago, the folks at Vehicle Craft Incorporated also seemed to be a good resource for this conversion.

Gotta disagree with Steve on the other calipers like the 951 units. They are excellent for racing.. on 951's. I think the issues arise when folks fit them up 911s and don't have a good system design. I know for a fact that Boxster brakes work great on racing 911s in the rear, for the right cars with the right system design.

For 911's it is hard to beat the 930 parts.