ZR1 Track Day update (road course) - didn't go well :(

[cbaclawski]

My track day got rescheduled from Sat to Sun(yesterday) due to weather. That part worked out great as the weather was beautiful...


I had big plans of coming back here, sharing some video, data screen caps, etc., but alas, it's not to be.


Being my first time out in the car I was taking the first session easy at first, braking early and not pushing it in the corners. Around lap 4 as I was slowly picking up speed, I was heading in to a high speed corner (Turn 8 @CMP for those familiar), went to brake, and the pedal went straight to the floor. I tried to make the corner way too hot but couldn't hold it and spun right off the track.


Getting to the pits, it was suggested that by going so easy I'd been dragging the brakes and the pads (hawk HP+) had overheated. Sounded reasonable, but just in case I let it cool and bled all 4 corners. The fluid was clear, obviously not boiled, and no bubbling at all.


Thinking all was well I went back out, this time braking harder and shorter to avoid what I thought was the issue in session one, brakes seemed better but sill very inconsistent. Around Lap 4 again, in the same spot, I spun off track. Once I pulled back on track, the pedal was completely gone and I limped back to the pits. Consulting with some other drivers, they said it could be caliper piston lash and I should try to give it a pump before the braking zone. (apparently this happens a lot in spec miata racing)


After a brief time in the pits, and with no frame of reference on how the brakes were *supposed* to feel, I assumed the brakes on the z just sucked by design. I headed back out for the third and final time. This time I was going to keep it on the track for sure. Unfortunately, on lap 2, while I was really still warming up, I couldn't get slowed for turn 4, lifted and spun again, this time in to a tire wall, ending my day.(and the pristine condition of my front end)

With a day to replay the days events in my head, I'm 99% sure I have a failing master cylinder, which led to brakes that ranged from wildly inconsistent to non-existent. Thinking back to the bleed, the person I had pumping the pedal for me mentioned that the pedal was sometimes slowly going to the floor before I even opened the valve, and when I did crack the valve I didn't always get that much fluid, sometimes more than others. Shame on me for not recognizing the problem sooner and calling it a day before crashing out.


The good news is the damage is superficial and can/will be fixed, also when the brakes did work, the car was better than expected in the corners. virtually no body roll, good grip, and it was easy to hit my marks. I did have to be more careful with the throttle than I am used to in my lower hp cars, but overall very manageable and predictable.


Can't wait to get the repairs done and get back out there...


Curt

[ghlkal]

I imagine most of us have similar stories on our first times out (I was 360 several times at Autobahn in Illinois, but let's not talk about that :p )


I would think this is a mechanical issue as you surmise. I'm glad the damage isn't too great, and that you're ready to tackle it again.


Keep us posted on the progress.

[tnova]

This is why I’ve put the Wilwood brakes in and upgraded the master cylinder. I just didn’t have confidence in my brakes compared to other cars I’ve driven in the track. Agree on your master cylinder analysis.


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[cbaclawski]

I imagine most of us have similar stories on our first times out (I was 360 several times at Autobahn in Illinois, but let's not talk about that :p )


I would think this is a mechanical issue as you surmise. I'm glad the damage isn't too great, and that you're ready to tackle it again.


Keep us posted on the progress.

1st time out *in this car* I have plenty of experience in other cars... enough that I should have known something wasn't right...

This is why I’ve put the Wilwood brakes in and upgraded the master cylinder. I just didn’t have confidence in my brakes compared to other cars I’ve driven in the track. Agree on your master cylinder analysis.


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For now, just going to replace the cylinder and give it a good road test before taking it back to the track. If I still don't have confidence in it, a full upgrade is next. Definitely no more track until I'm 100% sure it's working as it should... brakes are kinda important...

[RussMcB]

Been (near) there, done that (or similar). Glad the damage was minimal. Any pictures?

Two thoughts: 1) I do think near-stock brakes can be made to work fairly well. Mine do, but (caveat), I have never gone more than say 5-6 laps really hard. I'm sure Wildwood and other upgrades are superior, but maybe not required, depending on your needs. I'll list my brake mods below.

2) I'd try hard to see if you can replicate some symptoms before you start the work. Easier said than done, I'm sure, but *IF* you can replicate a problem before you make changes, there's a better chance you'll be able to confirm your repair without going back to the track (and maybe not having fun). Maybe there's a country road with some coast down area. Maybe your emergency brake isn't affected by whatever your root cause is.

My mods: I rebuilt the calipers. It was a challenge to find the seals, but I might not have asked the right people (like Jerry's, Marc, etc.). I installed the stainless steel pistons from DRM, along with their brake bias spring (link below). Also steel braided lines and (aluminum?) backing plates that are supposed to stop some of the heat from getting to the pistons and fluid. Lastly, new, good quality rotors and racing pads (I forget which brand/compound, Hawk or Carbotech, I believe - purchased from someone here a few years ago).

http://dougrippie.com/category/products/corvette-1984-1996/brakes/

[cbaclawski]

Been (near) there, done that (or similar). Glad the damage was minimal. Any pictures?

Two thoughts: 1) I do think near-stock brakes can be made to work fairly well. Mine do, but (caveat), I have never gone more than say 5-6 laps really hard. I'm sure Wildwood and other upgrades are superior, but maybe not required, depending on your needs. I'll list my brake mods below.

2) I'd try hard to see if you can replicate some symptoms before you start the work. Easier said than done, I'm sure, but *IF* you can replicate a problem before you make changes, there's a better chance you'll be able to confirm your repair without going back to the track (and maybe not having fun). Maybe there's a country road with some coast down area. Maybe your emergency brake isn't affected by whatever your root cause is.

My mods: I rebuilt the calipers. It was a challenge to find the seals, but I might not have asked the right people (like Jerry's, Marc, etc.). I installed the stainless steel pistons from DRM, along with their brake bias spring (link below). Also steel braided lines and (aluminum?) backing plates that are supposed to stop some of the heat from getting to the pistons and fluid. Lastly, new, good quality rotors and racing pads (I forget which brand/compound, Hawk or Carbotech, I believe - purchased from someone here a few years ago).

http://dougrippie.com/category/products/corvette-1984-1996/brakes/


pic:
https://www.facebook.com/photo.php?fbid=10218517459594714&set=a.1079682639261&type=3&eid=ARDoSpC_cVM8uEcIbBFchYo6Kg7rtoBt1-icn04pACaV11CizD7O82I7TE8YqVZnEJmtMFqs5RgO0sL2

I have steel lines, new good rotors, and while not true race pads, pads that should hold up fine for 10 laps or so...

I'm pretty confident that it's the master. I think it's just hanging on well enough to sorta work sometimes, and not gone badly enough to show much on the street... I haven't rebuilt the calipers, but they seemed to function properly when changing pads, and not a drop of fluid anywhere...


I can't think of any other reason it would behave like it is...

[S.hafsmo]

This is why I’ve put the Wilwood brakes in and upgraded the master cylinder. I just didn’t have confidence in my brakes compared to other cars I’ve driven in the track. Agree on your master cylinder analysis.



What master cylinder did you use to upgrade?

[tnova]

First let me say I totally agree with Curt’s analysis and methodical approach. As for my approach it’s more based on my driving style as a very late braker when entering a turn, picked up as a driver of “momentum” cars that had to keep speed up since they had little torque. Late braking and early off. For me the ZR-1’s brakes didn’t address my “style”. That’s why I went to Wilwoods. May not be the right decision for others. Second, the master cylinder I went with was from a 4th generation Camarillo, an old school C-4 solution. You have to make a spacer to keep rod length correct and trim some clearance from the inner fender. Also the fittings are different so you have to remake the attaching line ends. I would suggest going to a somewhat larger ‘95 C-4 master cylinder to keep originality over the 1” 4th gen Camaro one if possible to meet your track needs.


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[cbaclawski]

First let me say I totally agree with Curt’s analysis and methodical approach.


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I just wish I had at least ridden in another c4 so I had a baseline as to how it was supposed to feel. I might have realized something was wrong before this "incident"

Prior to this car, the only C4 I'd ever driven was when I was in high school. My buddy and I would trick dealerships into letting us take one out for a test drive on the premise that "My dad was going to buy me a sports car for graduation and I needed to decide what I wanted" Believe it or not, in the early 90's, every dealer we went to was happy to toss the keys to a couple 16 year old's and let us take our car of choice out unsupervised for a few hours...

[Vette Guy]

Here's my $.02.... Don't simply replace anything - you need to find the problem and then see what you need to replace. Not sure a faulty master cylinder is the problem, and simply replacing it may give you a false sense of security for next time.

I think our J55 calipers are fantastic. They are nicely matched with the rears, and as Russ indicated, with the DRM bias spring make for one heck of a balanced braking application. I do race (88 Corvette Challenge) with the exact calipers and master cylinder (different brake booster) and am a threshold braker - meaning I typically go full throttle to full brake every lap, and I've competed the car hard on race tracks for the past few years. https://www.youtube.com/watch?v=hy6DG7In0sc&t=671s
Each test/practice/qual/race is 25-30 min. While I don't make a whole lot of power, I consistently push and catch up with faster cars in the turns. If you'd ride with me, you'd be amazed at what your stock brake system can do - it surprises me too! I've never once boiled my brakes, and a well balanced bias will stop you in a very short distance.

You started off with a faulty system if the brake pedal was going to the floor before you began bleeding the system... also, not getting a good bleed is another indication there is a big problem. My guess is that you have junk in your calipers and or master that will only be removed with a good cleaning. During the rebuild process, you should find the "ah ha" problem.

Prior to racing, I rebuilt the system - HIGHLY RECOMMEND the DRM pistons - I attribute my ability to keep the brake fluid from boiling to these pistons - my more expensive calipers on another race car do not have aluminum pistons - they transfer heat from the pads to the fluid quickly; the DRM stainless pistons will withstand much more heat.

A great time to rebuild and not replace your master cylinder is during the installation of the DRM bias spring. I found junk in mine that was blocking a passage for the rear brakes, meaning that I would have had too much front brake, and likely spun the car under any sort of hard braking. (in my case, I found a cracked spring withing the master cylinder, which then required I replace the master). Also, if there is any junk in your calipers, you'll find out when you switch out pistons. The rebuild kit for our J55s can be found at any Autozone, O'Rileys, or NAPA. I burn my dust shields almost every race, and replace them at the end of the season.

Lastly, use at least Super Dot 4 fluid (500 dry boiling point minimum). I recommend Pentosin, but started using Amsoil Dominator Dot 4 in the race cars - 580 dry boiling point, and it's not super expensive as is Motul.

Your existing brake system is likely more than you will ever need for a track day - and what was used during the Corvette Challenge and in later pro-racing series. Switching up to Wilwoods, etc., will require some time to find the proper bias. Don't get back on track without finding the exact cause of your problem.

To give you an idea what I run.... DBA 4000 series rotors (Club Spec with temperature indicating paint), Carbotech XP-12/10s, DRM pistons and bias spring, and >500 dry boiling point fluid. I don't recommend the same Carbotech models for street tires, rather you may like the XP-8's - which are grippier than the HP plus, but still streetable.

Regards,
Mark
http://s3.amazonaws.com/scardigest/wp-content/uploads/20160915100407/USVGP.16-28.jpg

[Vette Guy]

Here's a short clip of what I had to do to catch-up and pass another Challenge Car running a built engine with 100HP over my stocker.... it's all in the late / hard braking and cornering. Straight braking, no wobble, no spin.

https://www.flickr.com/photos/21561226@N05/30849573415/in/album-72157676290388995/

[cbaclawski]

Here's my $.02.... Don't simply replace anything - you need to find the problem and then see what you need to replace. Not sure a faulty master cylinder is the problem, and simply replacing it may give you a false sense of security for next time.

I think our J55 calipers are fantastic. They are nicely matched with the rears, and as Russ indicated, with the DRM bias spring make for one heck of a balanced braking application. I do race (88 Corvette Challenge) with the exact calipers and master cylinder (different brake booster) and am a threshold braker - meaning I typically go full throttle to full brake every lap, and I've competed the car hard on race tracks for the past few years. https://www.youtube.com/watch?v=hy6DG7In0sc&t=671s
Each test/practice/qual/race is 25-30 min. While I don't make a whole lot of power, I consistently push and catch up with faster cars in the turns. If you'd ride with me, you'd be amazed at what your stock brake system can do - it surprises me too! I've never once boiled my brakes, and a well balanced bias will stop you in a very short distance.

You started off with a faulty system if the brake pedal was going to the floor before you began bleeding the system... also, not getting a good bleed is another indication there is a big problem. My guess is that you have junk in your calipers and or master that will only be removed with a good cleaning. During the rebuild process, you should find the "ah ha" problem.

Prior to racing, I rebuilt the system - HIGHLY RECOMMEND the DRM pistons - I attribute my ability to keep the brake fluid from boiling to these pistons - my more expensive calipers on another race car do not have aluminum pistons - they transfer heat from the pads to the fluid quickly; the DRM stainless pistons will withstand much more heat.

A great time to rebuild and not replace your master cylinder is during the installation of the DRM bias spring. I found junk in mine that was blocking a passage for the rear brakes, meaning that I would have had too much front brake, and likely spun the car under any sort of hard braking. (in my case, I found a cracked spring withing the master cylinder, which then required I replace the master). Also, if there is any junk in your calipers, you'll find out when you switch out pistons. The rebuild kit for our J55s can be found at any Autozone, O'Rileys, or NAPA. I burn my dust shields almost every race, and replace them at the end of the season.

Lastly, use at least Super Dot 4 fluid (500 dry boiling point minimum). I recommend Pentosin, but started using Amsoil Dominator Dot 4 in the race cars - 580 dry boiling point, and it's not super expensive as is Motul.

Your existing brake system is likely more than you will ever need for a track day - and what was used during the Corvette Challenge and in later pro-racing series. Switching up to Wilwoods, etc., will require some time to find the proper bias. Don't get back on track without finding the exact cause of your problem.

To give you an idea what I run.... DBA 4000 series rotors (Club Spec with temperature indicating paint), Carbotech XP-12/10s, DRM pistons and bias spring, and >500 dry boiling point fluid. I don't recommend the same Carbotech models for street tires, rather you may like the XP-8's - which are grippier than the HP plus, but still streetable.

Regards,
Mark
http://s3.amazonaws.com/scardigest/wp-content/uploads/20160915100407/USVGP.16-28.jpg

Thanks much for the advice!


Much of what you discussed is pretty far above my level of mechanical ability. Replacing the master seemed like a quick and relatively cheap starting point. I did ask the owner/mechanic at the race shop I typically use for track car maintenance if there was a way to test the master to see if it was the problem, his response was "Not really, and it's cheap and easy enough to do, just throw the part at it". Also, when the brakes DID "work" I didn't notice anything to indicate a major un balance either front to rear or left to right. Perhaps naively, I took that to mean that it must be the master, as I thought it highly unlikely that I would have the exact same level of problem at all 4 corners at the same time. I already ordered the new master and might as well install it I guess...

I am running ultra high temp fluid, It was done at the shop and I don't remember the brand, but it is true racing fluid. I was planning on flushing the entire system with motul 660, which I have had good luck with and never boiled in my other cars, when I installed the new master. I also have replacement slotted rotors. Again, I don't know what brand as I didn't install them and forgot what I was told, but they are supposedly suitable for track use...


I *THINK* I'll be able to tell by pedal feel and how the flush goes if everything is working properly. If I have any doubt whatsoever, I'll read up on rebuilding the calipers, the pistons you mentioned, and whatever the hell a DRM spring is...


I don't plan on racing this car, and typically run 20 minute, occasionally 30 minute sessions with plenty of cool down in between. I agree with you that the stock calipers, with good pads and fluids should be easily up to that task if functioning properly.


I am willing to go to a full race pad if necessary, I'm unlikely to drive this car much, if at all, on the street. With the Racetech seats and 6 pt harnesses installed, it's not exactly easy to get in and out of, let alone comfortable to drive in traffic... (I'm about 6'3" 275, so that doesn't help)


Do you do anything for Brake cooling, i.e ducting? Just eyeballing the setup, it doesn't look like there is much airflow in there...

Thanks again, Curt



Edit - just saw the video - AWESOME!!! Everybody talks about horsepower, but it's brakes and tires that make you fast! - on a circuit at least...

[Vette Guy]

Curt,

You can still disassemble your old MC and see if it is filled with goop - brake fluid does go bad, and with moisture and time, can clog passages. If not getting full brake pressure to the back, I think you could easily spin the car. Also understand that many of the problems you will encounter on the track, you may never see on the street.

A real race shop can test brake pressure to each caliper.... (https://www.amazon.com/Allstar-Performance-ALL11020-Rotation-Pressure/dp/B003BZR0SQ/ref=sr_1_8?ie=UTF8&qid=1545192116&sr=8-8&keywords=brake+pressure+gauge) else just throw parts at it and let you tell them if it works or not on the track. Was the bleeding problem with one or both rear calipers? May indicate a problem in the MC bias mechanism. If only one caliper had this problem, there may be another issue. I've taken apart calipers and found gunk that looked like coffee grounds clogging the fluid path.

Also, brake cooling ducts are important - if you look at the photos, they are on the sides of the air intake (under the driving lights) - as setup by Chevrolet for the Corvette Challenge Series. 3" high-temp hose that directs air to the rotor, but does not go directly to the rotor. The importance of having a good slotted rotor is that it acts like a fan to uniformly cool the rotor surface. Should you purchase the DRM pistons, I don't believe you will have any brake fluid boiling issues, even without ducts.

Hope this helps!

Mark

[cbaclawski]

Curt,

You can still disassemble your old MC and see if it is filled with goop - brake fluid does go bad, and with moisture and time, can clog passages. If not getting full brake pressure to the back, I think you could easily spin the car. Also understand that many of the problems you will encounter on the track, you may never see on the street.

A real race shop can test brake pressure to each caliper.... (https://www.amazon.com/Allstar-Performance-ALL11020-Rotation-Pressure/dp/B003BZR0SQ/ref=sr_1_8?ie=UTF8&qid=1545192116&sr=8-8&keywords=brake+pressure+gauge) else just throw parts at it and let you tell them if it works or not on the track. Was the bleeding problem with one or both rear calipers? May indicate a problem in the MC bias mechanism. If only one caliper had this problem, there may be another issue. I've taken apart calipers and found gunk that looked like coffee grounds clogging the fluid path.

Also, brake cooling ducts are important - if you look at the photos, they are on the sides of the air intake (under the driving lights) - as setup by Chevrolet for the Corvette Challenge Series. 3" high-temp hose that directs air to the rotor, but does not go directly to the rotor. The importance of having a good slotted rotor is that it acts like a fan to uniformly cool the rotor surface. Should you purchase the DRM pistons, I don't believe you will have any brake fluid boiling issues, even without ducts.

Hope this helps!

Mark


Honestly, the bleed was suspect at all 4 corners, I wasn't the one pumping the pedal, I was at the track and didn't know the person in the car, but he was complaining that the pedal was going to the floor *sometimes* before I even loosened the bleeder screw. A few times when I opened the valve very little fluid came up the tube, other times it was much more and seemed normal. This is part of the reason I assumed it was the master, maybe a broken seal in there...


Despite this, in my infinite wisdom, I took the car out anyway. In hindsight I can't believe I was that stupid. (stupidity + inexperience = crash)


Thanks for all your help - I wish you were nearby and I could get you to have a look!

Curt

[GOLDCYLON]

Here's a short clip of what I had to do to catch-up and pass another Challenge Car running a built engine with 100HP over my stocker.... it's all in the late / hard braking and cornering. Straight braking, no wobble, no spin.

https://www.flickr.com/photos/21561226@N05/30849573415/in/album-72157676290388995/

Nice vid Mark :cheers:

[Vette Guy]

Thanks! And here’s one from when things go wrong.....

https://youtu.be/gw60JxU-zYQ


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[randy ransome]

I'm waiting on pins and needles to hear this story. Glad you're alright.






:USFlag:

[Vette Guy]

Thanks Randy! Built a motor for the Challenge Car (replacement Challenge engine #129) and went through bearings at Fontana, and then Indy with Brett after having it again rebuilt. Had the ‘96 WC GT car for a few years, only had it at the Gathering one year. Decided to bring it out to finish the year - tore it completely apart - everything except motor (LT1). Ran test day, practice, qual, and what you see is the first lap of the first race. Steel crank let go and blew out the front of the block. No warning. Fortunately it occurred right as I shifted. I didn’t immediately realize what happened, and did not immediately egress - my window net new and super tight, and once I realized there was fire, I had a hard time releasing it. (Will definitely practice egress!). Oil caught fire on the headers and burned the heat shielding in the tunnel as well as the rubber lower boot on the ZF (still looking for a replacement lower boot). Didn’t pull the fire suppression system, as I wanted to attempt to get it with the handheld first and avoid filling the car with AFF. The 5lb bottle bought time for the safety worked to get another to me, while awaiting firefighters to arrive.
Have engines for both cars currently with the race engine builder. He’s one of the few certified to build the sealed engines for the Trans Am series... (we in vintage are like the opening act for the TA series).
While not a ZR-1, I’ve learned a ton over the last 3 race seasons. Best of all, everything carries over to our cars. The Challenge Car is more ‘street stock’ and the WC GT is a whole different animal. Best advice for making a ZR-1 track ready is not to change anything as it is already very capable, rather make sure everything is operating correctly and bushings are fresh. It was developed on the track and provided to you with a track ready tuned suspension and braking system. Yes, it can be improved for the track, but you need to understand the impact of each change and ensure front and back are in sync. Same with brakes. There’s also a limit to how far you will want to go.... fast track cars make terrible street cars, and in road racing the engine is about 1/2 of the equation for having a fast car - chassis is the other.
Biggest bang for the buck I can recommend for the track is changing your alignment to provide negative camber, which will keep more of your tire surface on the track throughout the range of motion.
Currently planning to have one of the race cars at the Gathering this year, and may try to run it on the MSP for our track day. I’ll be leaving for a race immediately after the Gathering.


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[cbaclawski]

Thanks Randy! Built a motor for the Challenge Car (replacement Challenge engine #129) and went through bearings at Fontana, and then Indy with Brett after having it again rebuilt. Had the ‘96 WC GT car for a few years, only had it at the Gathering one year. Decided to bring it out to finish the year - tore it completely apart - everything except motor (LT1). Ran test day, practice, qual, and what you see is the first lap of the first race. Steel crank let go and blew out the front of the block. No warning. Fortunately it occurred right as I shifted. I didn’t immediately realize what happened, and did not immediately egress - my window net new and super tight, and once I realized there was fire, I had a hard time releasing it. (Will definitely practice egress!). Oil caught fire on the headers and burned the heat shielding in the tunnel as well as the rubber lower boot on the ZF (still looking for a replacement lower boot). Didn’t pull the fire suppression system, as I wanted to attempt to get it with the handheld first and avoid filling the car with AFF. The 5lb bottle bought time for the safety worked to get another to me, while awaiting firefighters to arrive.
Have engines for both cars currently with the race engine builder. He’s one of the few certified to build the sealed engines for the Trans Am series... (we in vintage are like the opening act for the TA series).
While not a ZR-1, I’ve learned a ton over the last 3 race seasons. Best of all, everything carries over to our cars. The Challenge Car is more ‘street stock’ and the WC GT is a whole different animal. Best advice for making a ZR-1 track ready is not to change anything as it is already very capable, rather make sure everything is operating correctly and bushings are fresh. It was developed on the track and provided to you with a track ready tuned suspension and braking system. Yes, it can be improved for the track, but you need to understand the impact of each change and ensure front and back are in sync. Same with brakes. There’s also a limit to how far you will want to go.... fast track cars make terrible street cars, and in road racing the engine is about 1/2 of the equation for having a fast car - chassis is the other.
Biggest bang for the buck I can recommend for the track is changing your alignment to provide negative camber, which will keep more of your tire surface on the track throughout the range of motion.
Currently planning to have one of the race cars at the Gathering this year, and may try to run it on the MSP for our track day. I’ll be leaving for a race immediately after the Gathering.


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My expert opinion - It was probably the Master cylinder ;)

[randy ransome]

Wow Mark, I know you're having the time of your life racing in the Challenge Series. That video gives a good perspective of the process. I saw all the smoke and kept thinking when is Mark going to decided it's time to get out of there. It looked like you were being patience, cruising around the track then making the pass. Any idea what made the crank give up?

I drive my Z every now and then, not as often since getting my 67, and every time I do I'm still amazed at it's ability being a street car.

I was at the gathering the year you brought your Challenge Car, Nice!
Hope to make it back to the Gathering soon.

Good Luck and Have Fun Racing this coming year.




:flag2:

[RussMcB]

Thanks! And here’s one from when things go wrong.....

https://youtu.be/gw60JxU-zYQ


Sent from my iPhone using ZR-1 Net Registry (http://r.tapatalk.com/byo?rid=90383)Wow. Not fun too watch. Looks like you kept a cool head in spite of the challenges.

I had two thoughts while watching the vid. Whenever I have an issue on track (more than I want to admit), my first thought is to get as close to corner workers as possible. If you've ever watched a corner worker run to a car with a 10 lb. fire bottle, sometimes it looks like it will take them 10 minutes to get there.

I saw it was a challenge to get to the master switch. I've seen some versions that have a short rod to make it easier to reach, or a pull cable.

https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcR2sR5ha0oqXgQQtlalB83xH1DTbbcoN T440V9jTkbRqxxxNu2VWg https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRh45JHpoLVKJJ26YTnzf_np6mEIE69-CgiQhBZbryg-PFsOTy1

Thanks for sharing. Although it was a short session, the car sounded great, and the Glen is a really cool place.

My expert opinion - It was probably the Master cylinder ;)Ha ha! :-)

[Vette Guy]

Thanks Russ! It will go back together with a pull cable as you depicted.

[cbaclawski]

Update:

So since I already had the new master, I went ahead and installed it. I bench bled it using the syringe "reverse" bleed until I was satisfied that there was no air in it, then did it the traditional way with the tubes back to the reservoir.


I pressure bled all 4 wheels, going through about 2.5 bottles of motul 660 in the process, just to be sure I'd gotten a full flush. Then I had my wife pump the pedal with the engine running and did a traditional bleed at all 4 wheels. There was no air that I could see, and fluid flowed freely.


I just got back from a test drive, and the pedal felt better than it ever has, I heard the abs behind the seat self test at about 4 mph(though I couldn't feel anything in the pedal), and I'm pretty sure I was able to engage the abs with a full pedal mash from about 45 mph, though it only engaged after the car had already slowed substantially. I could definitely feel the abs modulate in the front driver wheel, but am not sure about the passenger side. I'm not sure if it engaged but the tire didn't skid, and it stopped straight - maybe because I was obviously sitting on the driver side I just couldn't feel it?

Does this sound about how it should?


Thanks and Merry Xmas!

Curt

[Vette Guy]

Sounds like you are good! Threshold breaking at 45 should be quick enough to detect a problem, but use the first track session to cautiously / gradually increase threshold braking speeds (assuming you are a threshold breaker!).

Just for grins, did you open up the MC? Clogged passage or cracked spring?


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[cbaclawski]

Sounds like you are good! Threshold breaking at 45 should be quick enough to detect a problem, but use the first track session to cautiously / gradually increase threshold braking speeds (assuming you are a threshold breaker!).

Just for grins, did you open up the MC? Clogged passage or cracked spring?


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I tried to open it(old master), but didn't know what I am doing and couldn't get it fully apart. I got all the hex bolts out, and the TINY spring at the tip(which seemed fine, but had so little "springiness" and was made of such flimsy metal, I can't imagine it did much, but couldn't figure out to get the piston out. I got the embedded c clip out on the end that attaches to the booster, but nothing slid out. I was getting brake fluid everywhere and eventually just put it down and moved on to another project...


I plan to bleed it one final time before tracking it again, and will be super careful at first. Might not be for a while. I still have some cosmetic work to do. I can only go once a month or so - less this time of year, and the e46 has been asking for a run...

Curt