DATSUN BRAKE DRUMS
by Lorne Goldman, Harald Sakshaug & the gang at the eMog Pub
May 1998, updated December 2002, updated December 2005, March 2008,January 2009, October 2009, August 2012, July 2015

REAR BRAKE TYPES

Pre-7/1993 self adjusting rear brakes
Post-7/1993 self adjusting rear brakes
Front Datsun Drums

Pre-7/1993 self adjusting rear brakes
Datsun Z drums, (designed along the same idea of the famous Alfin drums but frankly much better) were made in bimetal of cast aluminum with fins for extra cooling and a steel insert and used on the famous Datsun Z sports cars series.

The advantages are much improved rear braking, cooler drums, lighter weight and of course, the ability to shine them up to a gleaming finish (smile)..all without modifying the car. When I tested them, I tested them hard...yet when I stopped that car after some time of this, the brakes were only tepid to the touch.

This was years ago. The problem now will be to find used Datsun drums still in good condition with only acceptable wear. The maximum wear permissible is marked on each drum on their inner surface. I used to see a good set go for $450 USD without machining. Curiously, the originals were available in Canada for $92 CDN up to 2008. I bought the last 11 sets for friends. The set I have in spares is the only new set in original 1970s packaging that can be found on the planet. :( I should know. I called and web-searched for the last year. Part number is 43206-E4100

UPDATE (October 2009) There have been Datsun-like drums for sale in Europe since 2007. At one time there were available from Morgan suppliers. However, these drums reportedly proved to be substandard, out-of-round and with unacceptable porosity in the casting. The Morgan trade wisely ceased offering them. Buyer beware as they are still being offered by other suppliers in the UK. To give you a refernece point I bought two sets from Dastun (new old stock they still had then) and another 5 sets for friends from 1998-2003. To date, NONE have exhibited any anomalies or faults, exactly like the 1000s put on Datsuns. I still have the backup set in its packaging after 20 years!). Most of these guys are racers and/or drive their cars agressively. I have a 300+ bhp Plus 8.

MACHINING

There is also some machining to do depending on what type of wheels your car was made for.

With a tip from Fred Sisson and some specifics on the machining from John Sheally II, I fitted a set first some years ago to my made-for-alloy-wheels Plus 8. That meant these drums (which come for four holes) must be drilled to to fit the Morgan five. As well, the centre hole must be enlarged to the Morgan standard and a small bit taken from the dust flange on their rims which will then fit over the Morgan rear back plate.  It is much wiser for you to refrain from filling the old holes with aluminum.  This can be dangerous and it is not necessary. The nature of the bimetal will cause 1 in 2 to crack if extraordinary precautions are not taken. As there is far and away enough structural strength in the modified drum and considering the holes will be cover by your wheel rim or wire wheel adapter, there is no need to run the risk for aesthetics. See the one at the bottom of the page..example on the far left..

The picture below shows your Morgan drums and the untouched Datsun beside it.

There are three mods necessary to get it to fit a car made for bolt on wheels.
 

1. Increase the size of centre holes "A" to match those on your Morgan drums. You will find that the two sides of the car are possibly slightly different. (smile)

2. Drill the new bolt holes "B" The Datsun comes with four and none will fit. It is best to overlap one of the new holes as best as possible over one of the old holes and then  others will be clear of the originals. It is a small thing but you can have him place the countersunk fixing screw for the drum as close to the overlapping hole as possible. He will have to play a bit to get it all right.

3. He must remove one half the thickness of the inner side of outer edge of the groove around the perimeter of the drum. That sounds complicated but it is clear when you are looking at the drum.  Simply put, the groove is not wide enough to accommodate the Morgan back plate...with this mod it will be.

P.S. If you are using your old brake shoes, you will have wait a bit of driving for the shoes to adjust to a new curvature of the drums depending on the difference in wear between the Morgan and the Datsun. If you are lucky enough to find new Datsun drums and the spirit so moves you, have one of the companies (i.e.Porterfield) making carbon kevlar brake shoes to make you up a set to match the curvature. You will be surprised at the braking improvement.

NOTE: With the older brakes and brake adjusters you should back off the brake shoe adjustment before fitting the z-drums as you would with any new drums and then re-adjustment as you would normally. If the brake shoes are still too tight you can remove the shoes (if you know how) and file a tiny bit off the contact points at the ends  to give you a little more leeway.

Post-1993 Self-adjusting rear brakes (wires)

The post-1993 self-adjusting rear brake made-for-wire-wheels Morgans have much less machining. The Morgan drums on these come already made for 8 holes (four to give clearance to the bolts holding the assembly to the axle and 4 to hold the drum on the assembly).

With the near identical bolt pattern on both the Morgan drum and the Datsun Z-drum there are no excess holes left as in the earlier cars. That will leave you with a very "clean" result.



1955 Plus 4

by Harald Sakshaug

Pulled the front brake drum off my 55 +4 yesterday, and preliminarily fitted the disk wheel hub with the drum back plate and shoes in situ. It fits. Then took the front drum brake, disk wire wheel hub and the Nissan Z240 aluminum drum to my workbench. Lads and ladettes, it is indeed possible to make a spacer which will fit on the disk wire wheel hub so I can mount the Nissan drum to it.

Hey presto, I have wire wheels on my +4 without having to convert to disk brakes. Much cheaper, and much less altering to the original layout. When I want to go stud wheels again, I just pull the wire wheel
hub and remount the studded one.

I'll pop down to the local metal wizard shop for some lathe work to the drum itself, and have them to make two cylindrical spacer rings (one for each side) to fit over the wire wheel hub. This spacer will be mounted on the flange of the wire wheel hub with the 5 connecting holes. Then the Nissan drum will be connected on the top of that spacer with the four bolting holes in the drum. 

The room behind the wire wheel hub is an issue, and I have a general idea how to make the connections, which is attached to this email as an image.  If anyone out there has ideas, opinions or just want to address me for advice, please do. It would be welcome. Harald



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