Exocet Tire lockup on track - old tires?

Hey guys,

I managed to get the Exocet out to a track day, and WHAT A FUN THING. That said I was struggling with lockup (and a tired, old engine). I **think it's just the tires, they're old - I'm replacing them, but they didn't come in time. They're 6-7 year old r888s. What's crazy is the car was still completely hooked up - so fast in the corners!

I have Hawk Blue 9012 pads on it in the front and garbage rear pads. It would lock up the back on certain corners and the front if I applied any amount of brake pressure. 

You can see a bit of rear lockup in this video @ 3:19 (and yes, I know I'm terribly off-line - I missed a shift there and got flustered - still getting used to the 6-speed and short shifter)

https://youtu.be/lzW3nT3JIwY?t=189

What say ye?

So it's locking both the fronts and rears at different times? Why do you have garbage pads on the back?

Get some real tires on there and we'll see. I find that light cars like the Exocet seem to need better tires to wake up the chassis - I think you need grip to get the weight transfer going. I like to match the front and rear pads and install a brake proportioning valve. Set it so the fronts lock just before the rears, and be prepared to adjust the proportioning for different grip levels.

I have a set of older R888s which behave about the same way (cornering ok, braking less ok), and are downright scary at colder temperatures, so I would believe that the tires are part of the problem.

I had a bad experience on track with garbage rear pads and race pads up front (Gloc R10).  Something about the way the pads bite vs. pedal pressure… the garbage semi-metallic pads would lock up at the pedal pressures needed to get the required brake torque out of the race pads.

This was not on a miata, but it was on a car that was both lighter than stock and more front heavy than stock, with no changes to the factory brake bias.  I imagine all of these things are true about your Exocet as well.

In reply to Keith Tanner :

"Get some real tires on there and we'll see."

Do you not think that new r888r's will be enough to "wake the up the chassis"? I was looking at Hoosiers, but the cost and wear is a lot higher - and then I have to get a second set of wheels too. 

I've always considered r888s a compromise, but they're pretty sticky and they wear very slowly on light cars....

It's not the R888 part, it's the 6-7 year old part  

R888s are fussier than some other tires, I'm rather partial to the Toyo RR as a budget Hoosier alternative. I find they act like a sticker, shorter-lived RA1 - that's high praise.

In reply to Keith Tanner :

Roger! That's what I thought you meant, but wanted to be 100% sure (I paused my tirerack order, lol)

As for garbage pads on the back - that's how I ran my NA6 (I guess more weight over the rear helps?) - I've ordered matching Hawks to go on it. R888R's are inbound - I think I'll move to Hoosiers next season. I was already having to learn that with my anemic little 1.6, on the front straight at Barber I was applying pretty much 0 brake pressure going into 1 (just breathing the throttle) and then straight back to full power. I was all over much more capable cars through there - so fun. Much more sticky without adding power and I'm pretty sure there'd be only be 2 brake zones, lol.

Of all Miatas, the NA6 is the one where you need the best rear pads! They've got an excess of front bias from the factory. If you've got the 1.6 prop valve on your Exocet, you'd probably benefit nicely from an adjustable valve. Cheapest brake upgrade around.

In reply to Keith Tanner :

lol - well my dumb is showing! Ha - will order it today as well (flyinmiataaaaaa). I usually stick with r888's because I'm running those silly 13" wheels btw - I have the choice between hoosiers and r888!

Here's another video with the Exocet running. 

https://www.youtube.com/watch?v=zOJXq4ASdVM&feature=youtu.be

The guy in the Jaguar was quick - hence I tried to point him by before getting around that porsche

Keith Tanner said:

It's not the R888 part, it's the 6-7 year old part  

R888s are fussier than some other tires, I'm rather partial to the Toyo RR as a budget Hoosier alternative. I find they act like a sticker, shorter-lived RA1 - that's high praise.

To add to this it depends on what the R888R's were on before this. Heavy cars will eat these things up with heat cycles long before they lose tread. On the 65 spec racer most people don;t even run them 18 months out of the first heat cycle. 

In reply to wearymicrobe :

They were regular ol' r888's. Used on a gutted EG civic, a track rat gutted 92 miata -> then the Exocet. Anything else I should know about keep the new r888r's alive as long as possible?

Also proportioning valve ordered through Flyin' Miata - I'm hoping to cabin mount it and do the hardline to the rear simultaneously. 

Oh yeah - I met Randy Pobst too.

Randy is everywhere, and always super-friendly.

Hawk Blues are really grabby pads, especially when they're cold-ish.  They're an old design, if I wanted a hard-core track compound from Hawk these days I'd go with a DTC (30, 60, 70) compound instead of the Blues.

How much power are you making on the Exocet?  What brake hardware?

In reply to codrus :

Not much power stock na6 - I actually quoted the wrong part # (those are the pads on my escort) - I have their "light" duty autox/track pad. They were just what I had handy. I figure as low power and slow as it is they should do for now. Brake hardware is all stock na6 all the way around.

Nice beard 

accordionfolder said:

In reply to wearymicrobe :

They were regular ol' r888's. Used on a gutted EG civic, a track rat gutted 92 miata -> then the Exocet. Anything else I should know about keep the new r888r's alive as long as possible?

Also proportioning valve ordered through Flyin' Miata - I'm hoping to cabin mount it and do the hardline to the rear simultaneously. 

Then just trashed by time. Find somebody local or at the track with a durometer and see how they compare to someone with a newer set.

mr2s2000elise said:

Nice beard 

Lol - thanks! Usually it's much neater - no windshield and a helmet means my beard takes a beating at track days. 

In reply to wearymicrobe :

That's what I figured - any hints on keeping them happy for long (besides the normal)? I see Keith mentioned he sees them as fussier ?

accordionfolder said:

In reply to wearymicrobe :

That's what I figured - any hints on keeping them happy for long (besides the normal)? I see Keith mentioned he sees them as fussier ?

There are a bunch of "care and feeding of" white papers out there for various compounds of race tires.  I don't know if there's one specifically for the R888r, but there are some things that are common to all of them.  When you're not using them, keep them warm, keep them out of the sun, and away from ozone.  They have a limited shelf life even in the best conditions, how much will vary by tire but don't expect 3+ years out of any of them.  If you're not using them up faster than that, then you should think of this as an excuse to go to the track more often. :)

I find the R888 to be a little fussier about temps and pressures than the other Toyo R comps such as the RA1 and RR. They were the tire in Spec Miata for a while so there’s a pretty solid knowledge base on how to make them work. 

If you’re running 13”, have a look at Avons. Seems to be the go-to tire for Caterhams, which are lighter than Exocets but closer than anything else out there. 

There are loads of choices for 13" track and race tires. I don't know what your Exocet weighs but if it's closer to 1400 you may be able to use take off race slicks. Some of the track day sports racers are pushing 1400lbs so those tires would work. Used slicks will likely have enough life in them for track day use.

Avons are indeed good tires but in general they are more costly than Hoosiers. I've used the ACB9s (bias ply vintage tire) and they were super predictable. In fact you could hang the car way out with ease. Avon radials can be pushing $300 each for the size you may want.

I use a Hoosier vintage TD and 20.5 x 6.0 -13. They have a couple of advantages, they are light (11lbs per tire) and the shorter tire not only lowers the car it also helps the acceleration. In your case the narrow tire would also cut the frontal area, as you know the aero-drag on an Exocet is huge. The only change you need for bias ply tires is they need less camber. The Hoosiers cost me $188 a tire. 

I've driven a friend's Exocet extensively and they are huge fun. You can do things in them that other cars simply cannot. You can set some seriously quick lap times or chuck them about like a hooligan.

I’d put a 1.6 Exocet at about 1475 wet. 

Keith Tanner said:

Randy is everywhere, and always super-friendly.

Clarification - It was honestly a bit disappointing to meet him (never meet your hero?) - this is after having him flick me off and shake his fist at me on the warm up session of the day for being "too close" - at the time I didn't know it was Randy Pobst (I didn't even know he was there). It's a waving yellow lap so I was playing with the car and trying to get a feel for it (zooming about, having a good time) and he was behind another slower car cutting a very neat line that I was following to get my head right. I initially thought he was trying to point me by (a big no-no)- he was gesticulating so emphatically (that made me get closer trying to figure out what he was yelling, hahaaaa). He was waiting to tell me all about it by my car while I was chatting with my friends. As you can see in the picture I found the scenario hilarious, and he didn't seem too bothered despite his hand motions....

Keith Tanner said:

I’d put a 1.6 Exocet at about 1475 wet. 

Huh - I always assumed it was closer to 1600lbs, but I was looking at builds with 1.8s (mine still even has the 1.6 diff)