Disc set-ups are more expensive to manufacture and repair than drum set-ups, which is why many cars still come with drums in the back. The physics behind them favors the disc set-up as far as applied stopping power, and they run cooler too -- resulting in less "brake fade".
I agree with Marc regarding the non-essential need to go with 4-wheel discs. Hot VWs did a rather in-depth review on brake kit installations about ten years ago and how they performed with regards to a stock VW Beetle. First they measured 60-0 mph braking distances with a stock 4-wheel drum set-up. Then they converted the fronts to discs and retested, resulting in what I can remember being a 20-25% decrease in braking distance. Finally, they upgraded the rears to discs as well and got maybe another 10%. They didn't test a Type III rear drum upgrade as Marc suggested -- and what Sharkey runs -- but I would have to think that it would be somewhere in between (maybe an additional 5% over a front-disc set-up). The real advantage of front disc brakes, therefore, is in safety. As a secondary benefit, you no longer have to adjust them. Rear discs add a bit more safety as far as reducing braking distances go, and I can understand the mentality that "every little bit helps", but when I upgraded Sharkey to Type III rear drums, a complete rear disc system (w/ parking brake) was still upwards of $600-700 US. My Type III conversion cost me less than $100 (albeit, with used parts). Of course, rear disc set-ups are cheaper today. Really, the main advantage of rear discs is *not* having to adjust them. The only downside to disc brakes is that they generate more brake dust. If you have aftermarket wheels on your car, or even stock wheels that you really like to keep clean, you will have to wash them more frequently. Drums trap most of the dust, and what little escapes does so inward towards the center of the vehicle. Disc brakes shed lining material all over the place -- mostly outwards in you are running backing plates. You can get special shields designed to fit between the wheel and the rotor/caliper, but then you reduce your cooling. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of marc vellat Sent: March 20, 2007 5:36 PM To: Air-Cooled Volkswagen Discussion List Subject: Re: [vintagvw] Disc brake suggestions? Personally I don't think you really NEED any more brake on the back of a street Bug than Stock Type III rear drums would give you (and they're a simple bolt-on) but if you must have disks, the stuff from the back of a 924S or 944 Porsche (early, pre`85½ IIRC - the ones with stamped steel not alloy control arms) is a fairly easy approach. They'll increase your track width so fender clearance could be an issue, and of course they come with the 5x130 Porsche bolt pattern so they'd need to be redrilled if you wish to keep 4x130. My son put a set on one of his project cars, a `69 Bug, without any drama. I had to bend up some custom brake pipes, and the Porsche "swans" (e-brake cable levers so named because they resemble water fowl in profile) have to be replaced with some aftermarket pieces made for the job but otherwise it's a very straightforward operation. Here's a few snapshots: http://smg.photobucket.com/albums/v212/KaferChris/Project%2069/ I don't recall the source for the adapter swans off the top of my head but if you decide to go this route I'm sure my son could find it for you. Some folks have gone to the trouble to fit master cylinders from other makes of car when doing a 4-wheel conversion but IMO it's not really necessary. And if you only convert the fronts (with or without upgrading the rears to III drums) the stock Type I M/C bore of 19.05mm is exactly what was used on both 'Ghias and Type IIIs. I don't know for sure what calipers came on Euro Supers but I suspect they were single-pin Karmann-Ghia. Without an overseas connection to find you the disk-brake spindles you'll probably do the same as everyone else and use adapter brackets like Topline sells. The single-pin calipers are obsolete anyway - what's used to replace them (and in almost all the kits on the market) are Brazilian-made reproductions of double-pin `66-`71 Type III calipers, which have a sightly larger bore and pad area but fit the same spindles & rotors. --- No Quarter <[EMAIL PROTECTED]> wrote: > After driving Li'l Red for 10 years now, I'm > thinking about switching over > to disc brakes. I don't know much about them other > than they are pretty > much maintenance-free and I like that. At 35 years > old, I'm not as spry as > I used to be and it's a major pain to be down there > adjusting brakes like > what seems like all the time. My spirited driving > doesn't help matters any > though I assume. LOL! > > I remember from years ago that the disc brake > conversion kits came in > different forms. There were just the front > conversions, the 4 wheel > conversions which made you lose your e-brake, and > dune buggy style like the > Neal brand and so forth. > > What I'd like to find is an all 4 wheel conversion > kit that allows me to > retain my e-brake cables (the stock ones preferably > but not necessary), let > me continue to run my stock 4 bolt rims (this is a > 1974 Super Beetle), and > basically keep everything as stock as possible. > Wasn't it the Euro 1303's > that had disc brakes? Does a 4 wheel conversion > mean a different master > cylinder? Is a good trade-off to just do the fronts > and keep drums and > shoes on the rear since the front is what wears the > most anyway? I'd > appreciate all different opinions, advice, and > real-world testimonials on > the subject. I think it's time for me to convert - > whether it be 2 wheels > or 4. Thanks all. > > Erin ____________________________________________________________________________ ________ Looking for earth-friendly autos? Browse Top Cars by "Green Rating" at Yahoo! Autos' Green Center. http://autos.yahoo.com/green_center/ _______________________________________________ vintagvw site list [email protected] http://lists.sjsu.edu/mailman/listinfo/vintagvw _______________________________________________ vintagvw site list [email protected] http://lists.sjsu.edu/mailman/listinfo/vintagvw
