The track is hard on brakes

[jwasbury]

I put new front rotors on this car just over 2 years ago. Just bought a new set that I am going to install soon. I think I can get a couple more days out of these. Any thoughts.



I am installing a cooling kit in the hopes that it will help extend the life of the rotors. These have something like 8-10 track events on them.

[saxen]

drilled rotors are going to do that- no way around it. have you considered going to just slotted or stock rotors?


they should be fine for a few more days on the street- I wouldent track them like that

[jwasbury]

Slotted rotors will crack too as I understand. The holes in these rotors aren't drilled, they are cast in. I am not aware of any slotted rotors made to fit the 930 floating hats ('78-'79 model years only) other than Coleman's offered by VCI. Reviews on these rotors are generally not favorable.

[Cajundaddy]

Put a mic on em. If they are not below min runout, they are safely useable. Visually they look pretty far along though.

[Ronnie's.930]

This is a very interesting read on brake rotor cracking (and it concludes that increased cooling is one of the things that can lesson thermal cracking - as you mentioned you intend to do)-

https://www.cis.rit.edu/~cnspci/references/mackin2002.pdf

[pkracer21j]

Jacob, Check out Clint's front rotors...reasonably priced per pair and no holes to crack!
brake system components Rebel S Racing Products

[jwasbury]

Originally Posted by pkracer21j

Jacob, Check out Clint's front rotors...reasonably priced per pair and no holes to crack!

Interesting, thanks for the tip Pete. I will need to check into this. Already have a set of O.E. Sebros ready, so it will be next time around. The pricing is only a little cheaper than O.E. but that's with the hats. It says rotors are replaceable separately for less cost.

Honestly, at this point I am trying to minimize the amount of time, energy and $ I put into the 930 for the purpose of making it increasingly track worthy. Starting to seriously think about a dedicated track car. I plan to take notes with the new rotors to document how long they last. Hopefully the addition of cooling ducts will make them last longer. I've read where 911 guys using the '78-'79 OE turbo set ups get a lot of life out of them, so I think I should be able to do better...honestly I am not that fast.

[billjam]

Originally Posted by jwasbury

... Hopefully the addition of cooling ducts will make them last longer. I've read where 911 guys using the '78-'79 OE turbo set ups get a lot of life out of them, so I think I should be able to do better...honestly I am not that fast.

I added some cooling ducts to my 930 and the difference was very noticeable. There was less fade and brakes were more consistent over a number of laps. It really helps get times down when you can be confident that the brakes will actually work at the end of that straight!
As far as being "not that fast", maybe gearing would help

[jwasbury]

Originally Posted by billjam

As far as being "not that fast", maybe gearing would help

I know, I know. I don't want the car down for any significant length of time during track season. Maybe you can fly up from Oz and install them for me

[eimkeith]

Originally Posted by jwasbury

I put new front rotors on this car just over 2 years ago. Just bought a new set that I am going to install soon. I think I can get a couple more days out of these. Any thoughts.



I am installing a cooling kit in the hopes that it will help extend the life of the rotors. These have something like 8-10 track events on them.

When you cracks that run from hole to hole or hole to edge, its time to replace them. I'd get a few more laps out of those first.

[Miguel Antonett]

They look marginal to me - a micrometer would really tell you where you are; however, when in doubts don't... I'd stick with the OEM unless you're getting real serious about making it a track car, is fo, all bets are off...

[fredmeister]

Originally Posted by jwasbury

Interesting, thanks for the tip Pete. I will need to check into this. Already have a set of O.E. Sebros ready, so it will be next time around. The pricing is only a little cheaper than O.E. but that's with the hats. It says rotors are replaceable separately for less cost.

Honestly, at this point I am trying to minimize the amount of time, energy and $ I put into the 930 for the purpose of making it increasingly track worthy. Starting to seriously think about a dedicated track car. I plan to take notes with the new rotors to document how long they last. Hopefully the addition of cooling ducts will make them last longer. I've read where 911 guys using the '78-'79 OE turbo set ups get a lot of life out of them, so I think I should be able to do better...honestly I am not that fast.

Jacob,
Doesn't look like the Rebel rotor set up is still a floating rotor so you lose that advantage that we have with the 78-79 MY, so keep that in mind.

That said, your picture shows cracks but they dont look like they are connecting holes together and as long as none are running to the outside diameter of the rotor I think your ok to get more laps out of these. I am no expert but I have run front rotors that looked as bad as this on track until I saw cracks to the outside edge(diameter) then I replaced them.

Cooling the brakes is a must and make sure to get a cooling duct that is specific to the turbo rotors that mounts ot the hub, and seal the hub center off with the little star shaped block off plate that certain vendors sell. You will also improve the wear rate on your brake pads this way too.
You might also want to monitor brake fluid loss from the reservoir on your master cylinder. Mine leaks out the vent tube from all the high g right hand turns so I had to install a catch bottle that I empty back into the reservoir between sessions.

Fred