OK, I got a jig setup to slot drums. I've been running slotted rotors up front on my Golf for 10 years and there is quite a difference. The slots allow hot gases trapped against the surface to escape keeping the brakes cooler. If the surface gets coated with water too(big puddle, etc.) this helps swipe it clean quicker. Slots tend to not chew up the pads or shoes quite as much as cross-drilling.
Pictured here the jig setup with rear drums for my Golf(any drum will work though). You may be asking why even use a jig? Go ahead and try this freehand, you could really make a mess of the brake surface trying to hold the cutter steady. Also note, setting up the slots 120 degrees apart is easy, I simply rotate the base mechanism up against the 'L' brackets over to the next setting(no guesswork).
One of the slots visible here, this is a passenger side drum for reference.
The slots offset 120 degrees apart(60 degrees is also possible).
This is an ideal trick for better braking if you weekend race and are class or budget limited. Instant message me if you need a set done, I don't charge much and we need all the help we can get.
May be less likely to crack as well vs cross drilled?
I have forgotten all the arguments for slotted vs drilled rotors...
(IIRC it usually boiled down to great taste/less filling after devolving into a flamefest)
Last edited by Piledriver on Tue Nov 27, 2007 8:37 pm, edited 1 time in total.
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
Your drum slotting is a great idea. I had CH Topping in California crossdrill our rear Ghia drums and they have been excelent for several road racing seasons, and I don't see why slotted drums should be any different.
Have you considered slotting the friction surface area of a flywheel?
People have tried drilling them and it almost always leads to cracks. But slotting might be the way to go. A slotted flywheel would help cooling and do all the right things for clutch disk gases and debris slotting does for drums.
I'd highly recommend slotted drums to anyone. If I had anything here that needed drums, I'd ship a set to you. Maybe the Formula Vee guys would be interested?
HP Clutch discs are frequently slotted or multi-segment, the stockers only occasionally.
I'm up to trying it, I'll have to track down a loose 228 Vanagon flywheel/PP... Are you up to reconditioning/balancing them too?
Want to use it with either a stock disc or possible a sintered iron one, with a stock PP. (That would need slotted too of course)
I'll have to Google to refresh my memory on the drilled v slotted discs arguments.
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
An automatic might make "warped rotors" more likely...
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
Piledriver wrote:HP Clutch discs are frequently slotted or multi-segment, the stockers only occasionally.
I'm up to trying it, I'll have to track down a loose 228 Vanagon flywheel/PP... Are you up to reconditioning/balancing them too?
Want to use it with either a stock disc or possible a sintered iron one, with a stock PP. (That would need slotted too of course)
I'll have to Google to refresh my memory on the drilled v slotted discs arguments.
I don't see why it wouldn't work for a flywheel too. Also of note, I plan to drill at least two tiny holes in the backing plate in-line with the slots to help vent the gases out instead of having them swirl up against the backing plate. Also, I used a curved file to clean up the edges of the slot(too small to photograph), essentially so the shoe doesn't make contact with a hard edge I rounded the slot helically a little.
I want to be able to do helical slots in the drums next instead of straight cuts, which shouldn't be too hard to modify the jig for.
