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On 28 Apr 2004 at 1:13, Dave Hall wrote: > I'm still worried by the suggestion Type 3 front and rear brakes differ a lot in > their contribution to braking. Every year my brakes are tested on a rolling > road, and the fronts go about 120 on the dial before locking up, while the rears > are around 220. There's no weight transfer operating, but in most normal brake > use, I don't think there is much of that anyway. In normal casual braking I think you're right: The stops are low decel and the weight transfer is small. At this point we are also a long way from maximal braking. Since the only reason for installing rear disks would be improve maximal braking (push the envelope) the question becomes how does this all work at the limits? The short answer is that I don't know, but things seem pretty well balanced, with no particular tendency for either the fronts or the rears to break loose first. You may be right. We could understand this better if we knew where our center of mass was. Didn't you have an article that published this? > Also, I suspect the volume of lining material that wears off from the rear shoes > is comparable to the front pads, Yes, this seems reasonable, but I wouldn't be surprised if pad material was tougher stuff that shoe material, so I don't know if this means anything. My experience is that rear shoes last MUCH longer than front pads: something like 30-40k miles for pads and 100k miles for shoes. > I don't see how consistent results on measuring equipment which is regularly > checked in accordance with the Ministry code can be ignored. I accept your numbers, but I don't know how to convert them to a useful measure of dynamic braking force. > Also if so much more of our braking was done on the front, wouldn't our front > tyres wear out quicker than the rears, or at least about the same rate? As it > is, my fronts do at least twice as many miles as the rears if you don't swap > them round. My experience is similar, but I have always assumed that most of the wear just came from driving, when most of the weight was on the rears. > On the front engined VWs it's the other way round, with traction and > braking on the same tyres. Absolutely. Rear brakes on front engine front wheel drive cars are almost pointless. Look at them sometime, they are tiny simply because if they were any bigger they would lock up the rear wheels instantly. > Before I rest my case, m'lud, I put it to you that the major reason our cars > were outstanding in their braking was precisely because they could produce high > braking force on the rear as well as on the front wheels. No doubt about it. Having the weight biased to the rear gives us a tremendous advantage, both in braking and in traction. This is what made Porsche so competitive for so many years. > As a side issue, rear discs on modern VWs is becoming the standard, to > keep up with the spec. from other manufacturers. Right. Putting disks on the rear of cars like this is just pandering to public misunderstanding. > This has increased the number of runaway parked vehicles, as the discs > cool and contract, releasing the brakes! Just a thought for those > putting rear discs on their Type 3s. Have you really seen evidence of this? A question for the guys with the early cars: How are the brakes on the early cars which had front drum brakes with dual cylinders and dual leading shoes? It's just possible that those brakes were as good as the later disks. -- ******************************* Jim Adney, jadney@vwtype3.org Madison, Wisconsin, USA ******************************* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org