When this issue goes to print

When Auto Union resumed production in the winter of 1949/50, it was done by necessity in a horse stable and had to buy commercially available parts – in order to be able to make motorcycles at all – which by no means met the requirements to be made today. This is especially true for the brakes used in the initial series, so no more will be said about them here. If you still have a DKW from the early months with its inadequate brakes, the most you can do is try to achieve something by tinkering, but it won't be very much in any case.

When this issue goes to print
When this issue goes to print

Figure 17: Section through the old brake with drive.

When this issue goes to print
When this issue goes to print
When this issue goes to print

Cut through the new rear axle from RT 175 and RT 250/2 onwards. Construction basically the same, only the hub is completely new.

When this issue goes to print
When this issue goes to print
When this issue goes to print

Figure 18: Using the caliper to check newly riveted pads for exact cylindrical shape – a brake with such pads can never hold, it needs a lot of rework.

When this issue goes to print

The until autumn 1953 DKW-own brakes give very much more, if they are also according to today's terms naturally no longer the very last and very most effective, therefore one made finally also with DKW the new light alloy full hub brakes. Now it would not make much sense to give here learned information about which delays must be achieved with the earlier and the new light alloy DKW brakes, very few people are able to verify that. Really important to know is that with a rear brake you can make the rear tire squeal on any kind of dry road with fairly light foot pressure. This even in such a way that the rear wheel locks up and if necessary even breaks out sideways. So a rear brake that can't make the rear tire whistle hard with moderate pressure is bad and needs inspection.

(Please don't be afraid of locking rear wheel. Even at high speed – i.E. From 60-70 km/h – you can slide 5-10 m on a locked rear wheel without any special driving skills, without having to do any magic. It is good to practice something like this on a quiet road and have a friend tell you when the rear wheel actually locks up completely. It's always good to be in the know with something like this, so you won't be surprised later on.)

In the case of front wheels, the view is still widely held that the brake must be dimensioned for a fairly large manual force requirement. So you want to prevent that someone, who clenches his hand in fright, blocks the front brake, so that the front wheel slips away from him. I am of the opposite opinion here and believe that a front brake must be designed as a pronounced finger tip brake. With a brake, which gives highest possible deceleration already with two fingers, I can approach me substantially more closely and substantially more surely to the adhesion limit of a front wheel than with a brake, which requires very large hand strength – hard grasping in the fright I do not consider a problem, in addition does not belong more than at the most 1-2 weeks of a certain self-education.

Consequently, the DKW front brake needs a relatively large hand force, it is therefore not bad, but designed for this large hand force. As a rule of thumb, a DKW front brake is good if you can make a grooved tire squeal very clearly on dry concrete or dry macadam with very moderate hand force. Of course, there is no question of blocking, when the brake is applied more and more, you only notice how the front tire starts to whistle. If you want to make a tire with a block tread squeal, especially one with a coarse lug tread, you either need a very strong hand or the brake must be in above average condition.

By the time this booklet is printed, DKW will have reworked the brake pads in the new production, so they are guaranteed to fit into the drum and bear on the full surface, so you don't have to worry about non-bearing pads anymore. But on older machines, and especially when a brake has been resurfaced, don't be surprised if it doesn't seem to be pulling. First of all, you can't expect any significant braking effect at all from a newly applied brake, because the pads first have to run in, which in this case means running downright smoothly. A brake runs in faster and better the more consistently and the harder it is used. So you approach every known braking distance with steam for a while, you don't brake as in normal traffic, but competitively, i.E. Hard, This heats up the brakes and pads and the pads run in fastest. This initial period must not exceed 300-400 km, then the newly applied brake must fully pull again. If it does not, then look absolutely, it is possible that by the new occupancy the jaws or the brake pads are not in good condition. Pads are tapered. Then the pads wear of course only on 3-4 mm width. One can no longer expect a reasonable braking performance. Evidence of this is a bare, very narrow strip in the drum, while the rest of the brake drum surface is covered with fine lining dust that can be wiped off.

Remedy is obvious, one sees yes, where the linings alone carried and one can file off this high, already polished place with a rough file. From now on the matter needs patience, because the split pads are driven again 3-500 km and if there is no very noticeable improvement in the braking effect, you check again and will then also see how much wider the bearing surface has now become. A brake lining is correctly and well worn in when it is mirror-bright all around and hardly shows anything of the original texture. If a brake pulls badly, but has perfectly bright linings, one should not get the idea of filing these linings rough – the brake would then only pull worse. The fault then lies somewhere else, either unsuitable pads have been used or the pads are thoroughly oily.

When this issue goes to print
When this issue goes to print

Picture 21: This is the famous felt ring of the old brake anchor plates up to and including RT 250/1, four-speed, which has to be replaced more often when lubricated with normal grease. Today this seal is much improved.

When this issue goes to print
When this issue goes to print
When this issue goes to print

Fig. 22: Typical brake lever position with linings that are no longer completely new. The cable is tightened with full force, the angle between the brake lever and the wire cable is too blunt, resulting in a loss of force. Readjust the brake lever by means of the fine toothing on the camshaft!

When this issue goes to print
When this issue goes to print
When this issue goes to print

Fig. 24: The new alloy brake hub on the RT 175 and RT 250/2.

When this issue goes to print
When this issue goes to print
When this issue goes to print

Fig. 25: The associated brake anchor plate unfortunately does not fit easily with its abutment to the forks of the old RTs. The wire pull abutment has two threading options of different heights for readjustment. Adjustment screw now on top of the hand lever.

When this issue goes to print

Especially the modern, very high quality pads, which give both high braking values and almost complete insensitivity to temperature during continuous braking, are also very wear resistant. A new brake lining therefore needs a correspondingly long time to run in until it shows its full effect, and patience is also required for the filing process described above. A slight oiling is possible after very hard, competitive driving or after fast passes, because it can be that some oil has bled out of the highly heated grease filling of the wheel bearings and got onto the pads. One sees immediately whether the hub part of the drum interior shows oil traces. As I have found so far, in such a case, contrary to all expectations, it is sufficient to wipe the drum dry, after 3-400 km of sharp braking, the brake pads have also recovered from the oil and grip again. There is a trick to this: As shown in Fig. 21, there is a felt ring on the wheel hub that keeps the bleeding oil away from the brake drum. Occasionally it obviously does not, and if it once did not, then naturally a new felt ring – by the way a penny article – is due. Do you have any plans at all for a vacation trip to the mountains?. Then it is completely no problem to donate a new felt ring to the hub right from the start, it will then easily withstand 1-2 000 km of sharp, competitive hunting until it starts to let oil through.

On older machines, even if the shoes have been resurfaced, the brake lever can have an unfavorable position in relation to the cable. It is mounted on the brake camshaft with fine teeth, so it can be conveniently moved to a suitable position: When the brake is fully applied, the brake lever and brake cable should form a right angle, according to Figure 22.

On the other hand, the routing of the wire cable to the front brake has an astonishing influence. Although it is a rule to avoid any superfluous bends and in particular any S-bends in wire trains, we spent weeks unsuccessfully working on a seemingly miserable brake until we came up with the solution to the puzzle: An originally wide hitch handlebar was replaced with the standard narrow solo handlebar. The brake cable belonging to the narrow handlebar would have been 4 cm shorter than the existing brake cable and was therefore not replaced, because after all 4 cm of cable length makes no difference! But it was a typical case of Denkste and only from helpless despair, because none of the common means to improve the brakes worked any more, we changed without any hope of success, just to have missed nothing, the 4 cm too long train against the prescribed train – lo and behold, from the same minute the brake pulled! That the S-bend now present is less than it used to be is hardly noticeable to the naked eye, but the effect is astounding.

(Similar applies for example to the clutch cable, which is fixed in its length to 10 mm by the factory, not for reasons of economy, but only for the power transmission. So, if you change the clutch cable at any time, make sure that the length of the cable is exactly the same, and if you are annoyed by a stiff clutch cable, you only have to shorten the clutch cable systematically and piece by piece, so that every unnecessary bend is eliminated – then you will need less power to operate the clutch!) Also the DKW wire trains have grease nipples for grease lubrication, according to a friendly old habit. Grease lubrication is good if it is taken care of continuously and fresh grease is available all the time. Old, gummy grease can make a train completely unusable, by the way I am still of the opinion that a train lubricated with oil still runs significantly better than a train lubricated with even the best grease imaginable. I am now once for oil lubrication, in addition there are nowadays with the workshops and the gas stations all possible oil lubrication presses, I have for my private purposes the extremely fastidious Magura oil fix.

The new full hub brakes do not have an adjusting screw on the hub, which used to be somewhat awkwardly hidden. Today, the cable adjustment has been moved up to the hand lever, just as with the clutch, and because there is less travel in this adjustment than in the old adjustment at the bottom of the hub, the abutment on the brake anchor plate now has two hooking possibilities for the cable, one lower and one higher, see Fig. 25. Up to now it was usual to make front and rear brakes of the same size on motorcycles. In the new light alloy brakes of the DKWs, this has been abandoned, but the former 150 mm hubs have been retained for the rear brakes, while the front brakes now have a diameter of 180 mm. In fact, one can get by with a small brake at the rear wheel, since the 4.5 m/sec² deceleration that is only possible at a rear wheel at all can also be achieved with a smaller brake without further ado. A front brake can be charged up to 6-7 m/sec² deceleration. In this case the large brake diameter proves to be precious.

Finally, a few tips from the DKW competition people: They didn't like the bleeding of the bearing grease during competition riding for a long time and consequently looked for a remedy. It has been discovered that the company Theodor Klüber, Munich 25, Gelsenhausener Str., Germany, has a brake cable of the same length. 7, special greases are available, namely the Univiston RB medium grade for hub lubrication, which does not melt out and does not bleed even when subjected to six-day mountain loads. For the lubrication of the brake cam shaft and for light greasing of the brake cam itself or of the head of the brake shoe, the Univiston ZB 9l GG grade can be used. This grease is also only needed in traces at these points, just as only a very small fingerful of grease is sufficient for each bearing at the hub. Lubrication of this kind lasts for at least one year and at least 20,000 km under normal conditions, so there is no need to re-lubricate during this period.

In itself, these greases are quite expensive as special products, the smallest available container is a tube of 500 g. Because of the high price, you will also ask in vain at workshops and in general in the vehicle trade, people prefer to use the cheap general grease red or blue or green, about 3 marks a can, and fall over if they should pay for a can of special grease something between 15 and 20 marks, in reality, of course, you drive with the more expensive special greases but cheaper, because you need much less of it and because you also do not have any trouble with it.

Like this post? Please share to your friends:
Leave a Reply

;-) :| :x :twisted: :smile: :shock: :sad: :roll: :razz: :oops: :o :mrgreen: :lol: :idea: :grin: :evil: :cry: :cool: :arrow: :???: :?: :!: