Board index Flathead Power-Technical Questions, Answers, and Suggestions K-Models K/KRTT Front brake identification

K/KRTT Front brake identification

Post Tue Mar 11, 2008 9:10 am

Posts: 66
Looking at Ks, KRs and early Sportsters, there seem to be three front brake variants used: a half width brake with an alloy brakeplate with a recess for the fork leg, a half hub with a slightly domed brake plate without the recess, and a full hub brake.

My parts books show the brake plates from the back, which makes it hard be sure what goes on what. The brake plate with the recess seems to be the correct one for a KRTT, but I have not been able to figure out whether it goes with the same half width brake hub/drum assembly as the domed version, or whether there are two different half hub drum/hub assemblies, and whether they use the same brake shoes or not.

Also, I have seen what appears to be a conical front hub on some KRTT pictures, before the switch to the full width Italian brakes. Was this a stock item, or a modification?

Post Tue Mar 11, 2008 11:49 am

Posts: 591
Location: Crewe, Great Britain

Hi Slindo,

Only 2 variants for street front brakes, 52 till 72:

52 till 61, 1/2 width, recessed backing plate.

62 till 72, full width, domed backing plate.

KRTT and XLRTT could be ordered with the optional -54R front and rear brakes:

front: conical alloy casting, shoes taken from the back brake (a bit wider...), reinforced casting -54R alloy back plate, special cam.

rear: radially finned -54R cast iron drum, reinforced casting -54R alloy back plate, special cam.
In 1965/6, when KRTTs really began flying, the smallest 49 teeth rear sprocket was too big. so H-D made some drawings, no parts supplied, so one could make the bits and fit the front conical hub, mated with the rear -54R backing plate, on the back and graft smaller sprockets to it. Obviously, the backing plate was moved to the left...

Patrick

Post Wed Mar 12, 2008 11:48 am

Posts: 188
Location: sweden
Wasen't -64 the first year for the full width hubs?

Post Wed Mar 12, 2008 11:50 am
panic

This is great new stuff!
Got any pics I can use for my big brake comparo table ( http://victorylibrary.com/brit/2LS-table.htm )

Post Wed Mar 12, 2008 12:15 pm

Posts: 591
Location: Crewe, Great Britain

Yes, Epinut, you're right... Apologies!!!

Panic, this is the front cast alloy -54R hub:

Image

The rear -54R back plate, reinforced wide web across for loads more rigidity, vertically, the welded bit is the added bit for putting the torque arm when on the rear left after 65/66. This one was an ex-Roger Reimann, bought at his shop 1996 auction:

Image

Image

The rear 54R finned drum:

Image

The full front wheel:

Image

Image

Patrick

Post Thu Mar 13, 2008 7:49 am
panic

Do you have the width of the front shoe?

Post Thu Mar 13, 2008 1:57 pm

Posts: 591
Location: Crewe, Great Britain

No, Panic, but they are rear street shoes, slightly wider than front 1/2 hub shoes and same as later 64 full width. Cams were machined different for more leverage, not flat like street.

Patrick


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