Following information from a club member, who had the spare wheel fly off, the following information is offered for the correct way of fitting the wheel studs to the real axle. The procedure is principally the same for front and rear except for the dismantling of the rear axle 1411 (early) and 1771 (late) For this objective it is essentially more complicated than the dismantling of the front hub. Unfortunately, the larger studs are much more important on the rear axle than they are on the front.

The old wheel studs with 8mm thread are often threaded through the flange of the rear hub. That is the hub is tapped (M8) to accept the studs. So that they will not come undone when the wheel nuts are tightened, one flat of the hexagon head on the early kr200 is retained by a welded steel cover that is prevented from turning by a cap head screw. The later ones were simply welded into place. The change procedure is as follows:

1. Steel cover/welded point should be ground away with an angle grinder. IMPORTANT: make sure you do not damage the shaft seal area of the shaft where the shaft seal runs.
2. Unscrew the wheel studs from the back. Sometimes this can be easier if you cut off the threads before removing the bolt. Of course you can also grind off the complete hexagon head and take the stud out from the front, but with this method everything is very warm and it is possible to damage the working surfaces of the shaft.
3. The tapped holes should now be opened out to 8.5mm and countersunk both sides.
4. With M10 taps (these should be in three stages: first, second and plug taps), cut a new thread into the flange face. CAUTION: the axle shaft is made of high quality steel and so you should lubricate well during each cutting with the tap and after each turn, turn half a turn back to break off the swarf.
5. The new wheel studs to the best of my knowledge are not available with the required 2mm head and so you must turn the head of a standard bolt of 30mm length. They should be high tensile bolts marked 8.8. These should then be threaded into the tapped holes from the rear and screwed in really firmly. All four studs must be vertical to the flange face.
6. Weld one of the hexagon flats of each screw to the flange (with a MIG welder). IMPORTANT: The rear axle shaft bearing surfaces and the oil seal surfaces should be protected during the welding operation against splatter. Clean up the welds with a grinder so that the clearance is maintained to the brake shoes.
7.  Now the brake drums must be modified and opened out to 10.5mm diameter to accept the new studs.

PS. For those who want to avoid the procedure on the front axles will have the problem that the rear wheel will need to have 10.5mm holes for the rear axle stud. That will not fit very well on the front axles on the 8mm studs of the front hubs. In one of the Messerschmitts that I bought many years ago (that is one that cost only DM50, driveable, and with TV (MOT) naturally!) I discovered that the spare wheel had 8 holes four of 8.5mm and four of 10.5mm; also not bad!

Minimum parts requirements are as follows:-

2 Rear Axle bearing 6205 Partsmart 1767 1 Rear oil seal Partsmart 1769 Pair brake linings Partsmart 1348

Tools

A two or three leg puller is required to remove the chain wheel after the taking off the retaining nut. The workshop manual shows a large and complicated extractor for removing the rear axle. However, the axle usually moves very easily after a few blows from a large hammer. Of course the shaft must be protected if this method is used and a soft metal drift is normally used for this kind of work. Failure to protect the shaft end will result in extensive damage to the axle and may even make it unusable.

In many cases the rear axle will be removed leaving the inner bearing and seal in position on the shaft. When this happens, a really special puller is required. The problem is that there is no available surface for a conventional puller to grip and the bearing is often so tight that it cannot be removed even after destroying the seal to allow the puller to fit behind it. In this case a special shaft bearing puller is required. A suitable one is marketed by the Sykes-Pickavant company in the U.K. and consists of two curved jaws that are bolted together under the bearing face. A conventional puller is then attached to this and will pull off even the most stubborn bearing. It is possible to make a similar device by grinding steel angle sections to grip the bearing face and bolting them together. If you do not have access to extensive workshop facilities, do not attempt this job. Bearing removal can take many hours and you may end up grinding the bearing off the shaft with consequent risk of damage.

Replacing the front drive pinion bearings

Be sure to complete the above-mentioned diagnostic work before starting, as this job is difficult and time consuming. These bearings rarely fail and it is not normally worthwhile dismantling and replacing the bearings unless corrosion is present It is assumed you have removed the entire rear suspension form the car to do this job although the engine can remain in place. Before removing the chain completely following the diagnostic checks, re-attach it to the large chain wheel. This will allow you to prevent the shaft turning while you remove the left hand thread nut on the carden shaft drive pinion. If the nut is very tight, put the rear wheel on the studs to help prevent the shaft rotating. The bearing housing can now be removed, (after removing the screws), by gently tapping the suspension rubber and the bearing will remain on the shaft. A special puller is needed to remove the carden shaft pinion – the Sachs puller for the corresponding carden shaft pinion on the engine is too big. Try to borrow an early MOC puller made from a carden shaft. (Do not cut up an old carden shaft to make one as these parts are now rare and valuable). If the above puller is not available, use a proprietary thin jaw puller. When the pinion is removed, the shaft can be gently tapped through the bearing, taking care not to damage the thread. Take care with the speedometer drive as this is easily bent when fitting the new bearings. Assembly is simple but remember to coat the housing faces with sealant to prevent oil leaks. The oil seal 1757 (available from Partsmart) used to seal the shaft on the drive end sprocket shaft, (located behind the Cardan shaft drive sprocket), should be replaced before re-assembly.

Partsmart now offers the following new parts for the rear drive unit:-
1755 Nilos ring ? 0.95 this is the cover fitted over the 6205 bearing behind the chainwheel. The purpose of this ring is to retain grease in the bearing and to prevent dirt entering.
1754 Nilos ring ? 0.95 this is the cover fitted over the 6304 bearing on the drive end sprocket (speedometer cable side) . The purpose of this ring is to retain grease in the bearing and to prevent dirt entering.
1757 Oil Seal ? 2.75 used to seal the shaft on the drive end sprocket shaft. Located behind the Cardan shaft drive sprocket. Replacing this seal normally requires the drive end bearing housing to be removed.
1433a Gasket for small chain cover plate ? 1.95 . This plate is often removed to allow access to the chain during replacement in case of breakage or if it accidentally comes off the sprocket during repairs or replacement of the chain.

The above parts are suitable for use on all KR200’s from chassis number 65186. Owners of early cars built from 1955 to 1957 use the earlier type rear drive. This uses 6204 type bearings in both the rear axle and front pinion drive shaft – Partsmart does not stock parts for this early type. However, if any parts are required for this early type drive, please contact Helga and we will try to locate them. With a rear axle of only 20mm diameter as compared to 25mm for later type, this unit is obviously weaker than the later one.

Partsmart offers the FMR spare parts book (Part No, 1804 at ?3) that identifies all the parts for both types and includes diagrams showing how the various parts are assembled. If you need other components for the rear drive, used parts are available from Derek Cole.

The KR-200 manual has a procedure for adjusting brakes that is somewhat deceiving. It states that the right brake adjusting screw will adjust the right brake and the left adjusting screw for the left brake. This may appear to be the case but it is not really true. If you look at the exploded view of the braking system you can see the brake pedal which is attached at the bottom and is free to rotate. Higher up on the brake pedal is what they call a ‘brake compensating bolt’. It’s not a bolt but is actually a rod. The brake pedal pushes on the center of the rod, as shown by the red arrow, and the rod is able to tilt. The ends of the rods are connected to the inside arms of the brake shafts. The outside arms of the brake shafts pull on the brake cables.

Now assume that the right brake adjustment is too tight. When the brakes are applied, the right cable will pull the brake shoe against the drum and apply some pressure. The ‘Compensating rod’ will tilt to rotate the left brake shaft and try to get equal pressure on the left brake shoe and drum. If you have trouble getting good brake adjustment, it may be in the brake cables but look at the pivot points of the brake shafts. I have found on my 48 yr. old Messerschmitt that the pivot points were rusted and one of the brake shafts was binding. After lubricating and getting everything to move freely, I now have good brakes.

The rear brake should be adjusted to operate after the front brakes are applied. With slight brakes being applied to the front, the rear wheel should turn freely and be almost starting to brake.