MRM331

Here's the latest one:


-Jason

WolfGT

Great video. I love the data module in the corner. My only suggestion would be to also include a rear view camera. It's always entertaining to see what happens to a car you passed. Or help explain some actions you take (maybe a car approaching from the rear).

Again, Great video.

MRM331

In addition to my Go Pro I also have a few flip cameras lying around I may try to mount in different places next time. One of them is a generation one non-HD flip which I have been told has much better audio capability than the later HD flips and the GoPro. I may mount it to the licence plate bolts and use it for the audio stream as well.

I also just ordered a remote GPS receiver which should do a much better job of giving me an accurate speedometer, track position and lap time reading.

The next event I'm attending is on the 21st of September and run by precision track time (PTT). They have the entire Pocono raceway rented for the day and are planning on running a 3.5 mile "mega" configuration of the track utilizing most of the tri-oval of the super speedway and all three infield courses:

http://www.precisiontracktime.com/wp...o-ptt-mega.pdf


It should make for some good video!


-Jason

charchri4

Great video Jason! I really like the data in the comer too.

I've had really good luck with audio off the license plate. It sounds a bit odd because it's so close and clear but if you mix it with your normal camera feed about 50/50 it works really well.

MRM331

Two weeks ago I did an awesome open track day with Precision Track Time at Pocono Raceway. They managed to rent the entire facility for the day which meant they could use portions of the main NASCAR track and all three infield courses to create a "Mega Configuration" of over 3.5 miles! Because they mandate that only those solo-ed by other organizations are allowed in they don't have to use the traditional "run group" type of format. The track simply opened at 8 and, other than an hour lunch break and two 15 minute breaks for the corner workers, was open until 6. All told I could have spent almost 8 hours on the track had I wanted. I had to go refill my tank about 6 times at the local WaWa so my on-track time amounted to only about 5 hours and 275 miles.

WOT for 5 hours is pretty hard on any car and I was amazed that mine had no issues that made me pull off and go home. Just to be on the safe side I purchased the "Gold" version of AAA coverage the week before which is probably why nothing actually happened. I'd like to do possibly three of these events with this group next year which means I think will have to look into some minor issues if I intend on keeping the car reliable during this type of abuse. These would include fixing a minor radiator leak, rebuilding my front and rear calipers (will probably upgrade rears to NB sport size in the process) and building a more stout rear differential. Currently the car is running a yard-pulled 7.5 3.27 factory LS rear from a 1995 Thunderbird. The rear has a missing breather so it has a tendency to puke gear oil after a track session. It also has unknown miles and a bit more lash than I like. It cost me all of $35 when I acquired it so I really can't complain. What worries me is when I had the rear end up to change the track wheels off I noticed it seemed a bit more "clanky" that usual which makes me think it may be on the way out. I have no desire to move up from a 7.5 so I may rebuild it with a new ring gear/pinion (3.08 most likely) and an aftermarket LS carrier. I'm thinking about an Auburn Gear HP series unit. Other than those areas I think it may also be a good idea to replace the 180K-mile front hubs and rear wheel bearings for good measure. I'm hoping to take care of the above while the rocker rust is being handled over the winter.

Here's the video:


-Jason

Sunshine Guy

Six trouble-free tanks of fuel in one day with the pedal to the metal says a lot about the platform, the engineering, and the workmanship in the car.

AAA approved!

MRM331

Thanks.

It says a lot about my father's ability to build an engine. In my mind my father's act of building that engine for me ranks right up there with his giving me life.

-Jason

charchri4

Jason what are you running for brakes on your car?

MRM331

The front has 4-piston Wilwood Dynalite calipers over 1991 VW Corrado rotors using custom hangers made by TrackSpeed and lines pieced together from genaric -3AN braided lines and fittings. The total cost was under $500 not counting pads.

On the rear I the car currently has stock 1994 Miata sized calipers/rotors. To balance the two ends I used a Wilwood adjustable proportioning valve in place of the stock 1994 ABS valve.

The pads were Hawk black compound. I tried blue first and prefer the black as they are somewhat easier to modulate, last a little longer and don't dust nearly as bad to and from the track should I choose not to change them there.

After 20k miles on the fronts and 180K on the rears I think a rebuild of both ends are in order. When I went to look up prices of reman loaded 1994 spec calipers I found that the larger 1999+ sport calipers are now only $10 to $20 more and the rotors are the same price. When I initially built the car 5 years ago this was not the case. Because of this I'll be upgrading to the larger size rears with the rebuild. I also have a Mazda 929 master cylinder and booster on the shelf that I picked up a few years ago as a possible upgrade. I may swap that in as well if I get the chance. I've read that the larger bore of the 929 master will make the brakes almost Porsche-like.

-Jason

V8droptop

I was discussing rear brakes the other day, and considered going some different routes on the rear. However, rear sport brakes carry an almost 11" rotor, correct? Maybe I may get away with leaving them alone for the most part. Since we shift the weight bias more forward, what's your opinion on the rears, any benefit from larger piston/swept area from a bigger caliper?

Larger master cylinder is a nice add, on my list. The larger volume would certainly help those 4-pots.

charchri4

Sport rears are 10.82 and standard rears are 9.87.

FYI the 1991 VW Corrado rotors Jason is running are 11.02. We really need to start a big brake thread around here...

V8droptop

Woudln't hurt. My daily driver has 12.7" rotors, apparently. Although its quite heavy. I am still giddy that those same brakes fit the Rx-7 hubs.

Corrado rotors sound like a winner, that's a decent amount of rotor. Just wish we could get a large swept area pad on there.

MRM331

My reason for going up to the 1999 stuff on the rear is not lack of braking. It's more focused on how hard the current rear stuff is working to get it done. Before I installed the adjustable valve the car didn't feel like it was doing it's best. From what I've read the 1994 ABS valve I had was the most forgiving for this type of situation but still not optimal. With the adjustable valve in place I was able to balance the front/rear bias pretty nicely and in doing so dramatically improved the stopping.

What I also did in the process inadvertently was increase the amount of work the rears had to do. I noticed after a hard track session that the paint on the rear pads had bubbled off completely when the front were fine. On the track the rear pads also wear down a bit faster than the fronts which again indicates that they are working too hard. Originally I had held off on the upgrade because everything for the sport brakes was just more expensive. The rear pads for the 1994 calipers are expensive enough compared to the universal fit fronts ($100 compared to $50 for the same compound), I really didn't want to add any more running costs to the car if I could help it. It must be the number of 1999 - 2005 Miatas now requiring brake work and thus increasing the number of available cores that has driven the price down. They are low enough now that if I were building a street V8 out of a 1990 - 93 I would not even bother with the 1994 stuff, I'd go right to the bigger NB parts.

The Corrado rotors are pretty awesome. They are heavy compared to the two-piece rotors found in most Wilwood-based big brake kits but the fact that they can be replaced for under $30 each is a big bonus in my book. Friction rings for two piece kits can run $80 a piece. As far as the swept area concern goes, the Dynalite sized pads pretty much cover the entire friction surface of the Corrado rotors. You may be thinking of the kits that reposition the Miata caliper over a Corrado rotor, not a Wilwood setup like mine. In those cases you have a little puny strip of contact area on the large rotor face. I really don't see the point of such a setup honestly.

What I would really love to see is a way to use same the Wilwood calipers I have on the front on the rear and cut my rear pad costs in half. The only thing keeping that from happening is the lack of parking brake that would result. Flying Miata has a Wilwood caliper that integrates a parking brake but the thing is an huge ugly SOB. Another option would be to mount a Wilwood mechanical parking brake on each hub oposite the caliper but that would require someone to make me up a custom mount. Still another option would be to mount a small rotor with the same mechanical caliper on the diff pinion. I've looked into the last two but the braking from both systems even on just a slight hill is said to be sub-par. Further I'm not too sure of the legality of the drive shaft mounted option here in the great Commonwealth of PA.

-Jason

charchri4

Jason if you are up to making a custom mount there are lots of rear caliper options that can retain a proper parking brake in the back and give you cheap pads. Mustangs I think to this day do not use a drum style parking brake. My current plan is to use 94 - 97 Camaro / Firebird rear calipers because the parking brake is exactly the same set up and though I have not tried it yet I believe the Miata cable will hook right on it and work with little effort.

Gator Bait

I have the Corrado with Wilwood caliper front set up also. In the rear I have an 100 inch rotor with a bracket to fit the stock caliper. The sweet are is about half the rotor. I wonder if ther later calipers will work on the brakets I have ('92 calipers). ..ya...a big brake tread just may be needed. Jim...to the bat'puter!

MRM331

'Nother one:

This one is from the very end of the day. Less traffic and more experience lowered my lap times down to a fairly consistent 2:53 per lap from the 2:57 to 3:05 I was running earlier.

The 27 minutes in this video pretty much document the most awesome 27 minutes I've had to with the car to date.


-Jason

charchri4

And that is saying a lot!

So in 275 miles on the track did you totally kill a set of tires and brake pads? Any signs of strain on anything?

MRM331

I do a lot of down shifting and compression braking so believe it or not I actually got away with the same set of pads I used for the two-day track day back in July. I had a back-up set ready to go but never had to put them on. Setting my MS2 to activate "fuel cut" after only .5 seconds of 0% throttle really slows the car down. You can see in the video where this cuts in when the injector duty cycle and pulse widths bars drop to zero.

The Nittos were on their fourth track day going in and still have tread after all this. Only one seemed to show any real wear, the right rear. I'd imagine it may have something to do with the two big banked turns. With about a third of the day left I swapped it with the left rear to try and balance them out. I had the car realigned before the event with zero front and rear toe. This seemed to cut uneven tire wear dramatically.

The only two areas of concern were the coolant and rear diff leaks. The radiator has some type of small leak about 3/4 of the way from the bottom which I was checking on constantly. The diff has always had a tendency to puke gear oil out after a few hard high speed turns. After looking into it I think the culprit is excessive heat from the Ford Traction-Loc's clutches on the track. From what I have read they seem to be a little overwhelmed when used this way even in an 8.8 which has a lot more oil to cool it than my 7.5. After looking at different options I think my best option for this type of road racing use may be a clutch less (and thus much less friction/heat producing) Eaton Tru-trac. If I can save the funds that is the route I'll be going.

-Jason

WolfGT

I don't know much about the road racing or street use diffs (my experience is in diffs for offroad use), so here is a noob question for ya.

The diff I got from Martin has an Eaton Tru-Trac. He says it is Torsen Style. Is that the "Clutchless" diff you are referring to?

charchri4

Yes tru tracs are torsens.

WolfGT

I know that, but does that mean "clutchless". Just not familiar with that term.

charchri4

Got cha. Can't say I have heard the term either.

BTW my 8.8 gets pretty hot too but that's probably because the moron who built hot rodded it by putting one of the old clutch discs in place of where 2 steels are suppose to go.

WolfGT

So you don't know? Or do you keep accidentally not answering the question.

charchri4

Sorry yes your tru trac has no clutches in it at all. It's all gear driven and has very low friction compared to an auburn type clutch pack diff of days gone by. It has some trade offs but is a far better unit than the old stuff.

MRM331

From what my research had shown me there seems to be three main choices: locking differentials (only really good for drag racing), clutch pack limited slip and geared limited slip. The clutch pack type employs a "pack of clutches or cones which are held in place with a spring or springs. The preload of the springs deturmines how much "slip" is allowed. Geared type has gears which sort of slip out of place and contact the housing to create the slip effect. Both are fine for road racing although the friction gererated by the clutch packs gererates heat which degrades the performance as they heat up. The fluid capacity of the 8.8 is twice that of the 7.5 which I think is why the Ford Traction-Loc (clutch packs) seems to be alright in roadracing 8.8's but boils over in my 7.5. I could repack the unit I have but to really make it work I'd have to add a cooler system which easily could run over $500. The geared unit at $400 or so looks like the way to go.

-Jason