thrustnut Posted August 6, 2009 Share Posted August 6, 2009 I was just talking to a buddy who's into VW Bugs and he was telling me that one of the "upgrades" they are doing for auto cross it drilling the drums to prevent gas build up under heavy breaking. He said that when tested the drilled drums produced results pretty close to a stock disk set up. Any one ever herd of doing this? Quote Link to comment Share on other sites More sharing options...
piston Posted August 6, 2009 Share Posted August 6, 2009 sounds like a good idea but if so, i dont recall seeing any aftermarket crossdrilled drums? Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted August 6, 2009 Administrators Share Posted August 6, 2009 Is upgrading to discs not an option? Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted August 6, 2009 Administrators Share Posted August 6, 2009 http://kalecoauto.com/index.php?main_page=product_info&products_id=1 I just couldn't resist... Quote Link to comment Share on other sites More sharing options...
rsicard Posted August 6, 2009 Share Posted August 6, 2009 What is the % gain in upgrading rear brakes to disk? Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted August 6, 2009 Administrators Share Posted August 6, 2009 If you have driven any of the old cars that had 4 wheel drums, especially on a track, then drove a modern car with four wheel disc, you will recall the difference in consistency, feel, etc. Having rear drum and front disc is only part way there, the S-30 Z car. No way to put a % of improvement on rear disc conversion. Gains are consistency in braking, not only in just how the rear brakes corner after corner but also consistency in the balance front to rear, feel, ease of maintenance, etc. Quote Link to comment Share on other sites More sharing options...
thrustnut Posted August 6, 2009 Author Share Posted August 6, 2009 I'm not too worried about myself, I don't race at all and recently upgraded to the Toyota brakes in the front and want to see the improvement before doing any other brake changes...that is unless I can get ahold of a set of BRAAP's cool looking lines (in tuner red of cource). I just wanted to know if any one had ever herd of doing this, I figured with the nature of the site and the raceing backround here, it would be the place to ask. He said there's a guy that charges fifty or seventy five dollars per drum to drill them. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted August 6, 2009 Administrators Share Posted August 6, 2009 I'm not too worried about myself, I don't race at all and recently upgraded to the Toyota brakes in the front and want to see the improvement before doing any other brake changes...that is unless I can get ahold of a set of BRAAP's cool looking lines (in tuner red of cource). I just wanted to know if any one had ever herd of doing this, I figured with the nature of the site and the raceing backround here, it would be the place to ask. He said there's a guy that charges fifty or seventy five dollars per drum to drill them. I recall hearing about it in the '80's, I'm sure it was done well before then. I think most of the budget guys were just slotting their brake shoes with a hack saw blade giving built up gasses an escape path. Guys were doing that with their brake pads for the discs as well, a bubba approach to slotted rotors.. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted August 6, 2009 Administrators Share Posted August 6, 2009 Some of of the mature racers that drove cars with drum brakes would know best, hopefully they see this and chime in... Quote Link to comment Share on other sites More sharing options...
rsicard Posted August 6, 2009 Share Posted August 6, 2009 I am going to upgrade the front 240Z brakes to Toyota calipers and Z31 rotors with a spacer then see what the braking differences are. When I get converted over to a V8 and six speed manual then take it to a road race course to see if the braking is sufficient. With the weight distribution it is easy to see upgrading the front brakes. It is harder to imagine a REAL gain from upgrading the rears to disk. I can imagine the old drum brakes on the front and rear becoming overheated rather easily in RACING. But ventilating the rear backing plate, drums and modern brake shoe material may have a LOT less heating and MUCH better performance. Quote Link to comment Share on other sites More sharing options...
johnc Posted August 6, 2009 Share Posted August 6, 2009 Drilling steel drum brakes is an old racer trick to lighten things up, not bleed off any brake shoe gas. Modern shoe (and pad materials) don't out gas enough to cause any issues like they did 35 years ago. Drilling the aluminum drums on the S30 is a waste of time except for: 240Z racers usually drill two 3/4" holes in the brake drum 180 degrees a part to make it easier and quicker to tighten the shoes up against the drum between race session. Mount the wheel correctly and you don't have to remove the wheel/tire to adjust the brake shoes. With proper (and constant) maintenance and upgraded shoe material the rear drum brakes on the S30 will perform as well as any disk brake setup and they are lighter. Look at lap times the ITS guys can run. Quote Link to comment Share on other sites More sharing options...
rxsleeper Posted August 6, 2009 Share Posted August 6, 2009 Hey John, you forgot that we occasionally have to drill the drums to remove them from the hub :) Quote Link to comment Share on other sites More sharing options...
johnc Posted August 6, 2009 Share Posted August 6, 2009 How could I forget? I just pulled off another set of drums from some struts I'm building for a customer. I ended up drilling one hole so I could pop the spring holding the shoes in place and get the drums off. Quote Link to comment Share on other sites More sharing options...
Jon 74 260Z Posted August 6, 2009 Share Posted August 6, 2009 and they are lighter Does anyone have data on this? (I'm not disputing it because I haven't come across the post where johnc gave wrong info but I'm wondering if anybody has put these parts on a scale...) And another thing my insomniac mind was pondering a while ago: Assume that caliper + rotor is of equal weight drum + shoes; if the rotor weighed less than the drum, wouldn't it have a performance advantage due to less rotational mass? All I know for certain is that when I did my rear disc conversion, I felt really good about removing weight when I took off the big, heavy drums. I felt less good when I hefted the rotors in place and then when I grabbed the caliper... Well, let's just say that because I wanted the whole setup to be lighter, I decided that it was. I didn't need an objective scale to confirm what my wishful thinking had already determined as fact. Denial is a wonderful thing. Quote Link to comment Share on other sites More sharing options...
johnc Posted August 6, 2009 Share Posted August 6, 2009 FYI... I'm comparing the weight savings from an aluminum drum S30 rear brake setup. Some of the S30s had steel drums and there isn't any weight savings compared to a disk setup with those drums. I put a brake drum, backing plate, shoes, springs, spring pins, washers, wheel cylinder, wheel cylinder clips, adjuster bar, adjuster wheel, and rubber rear seal on a postal scale. 12 lbs 9.3 oz. Quote Link to comment Share on other sites More sharing options...
thrustnut Posted August 6, 2009 Author Share Posted August 6, 2009 Wow...lots of info, thanks. My friend is thinking about auto crossing his 60-something Bug, which I think has steel drums all around. Sounds like for street applications and the occasional track day, swapping to disk would be a waste of time and money. Thanks John for all the inside info. Quote Link to comment Share on other sites More sharing options...
Jon 74 260Z Posted August 6, 2009 Share Posted August 6, 2009 I'm afraid to ask when the last time that postage scale was calibrated to within 6.875 grams... I think the answer falls into the TMI category. (thx for the info tho) Quote Link to comment Share on other sites More sharing options...
johnc Posted August 6, 2009 Share Posted August 6, 2009 which I think has steel drums all around. I'm only posting about rear drums on the S30. A bug is a different story and converting from front drums to discs is always a good idea, IMHO. Quote Link to comment Share on other sites More sharing options...
rsicard Posted August 6, 2009 Share Posted August 6, 2009 It sure is GREAT to get the straight scoop from a seasoned professional. Quote Link to comment Share on other sites More sharing options...
thrustnut Posted August 7, 2009 Author Share Posted August 7, 2009 I know...diffrent application, I agree about swaping the fronts to disk. I just wanted to know if this was somthing actually done, or if it was one of the "I knew a guy who knew a guy who raced back in the day" things. Quote Link to comment Share on other sites More sharing options...
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