Triumphrat

Panheahpollock

Alright all you veterans of the 500cc T100. What year did they change from a roller bearing to the brass bushing in the 500cc T100. There is an ovious difference. Any help on this subject?

Cafeparts

I believe the change from bushing to bearing was done in 1968 for the '69 production year. The photos show the obvious difference between the bushing and bearing motors. The early type unit 500 motors have the smooth casting where the later type castings have the large boss around the timing side bearing area.

panda

If I were to take your question literally they didn't.

However this may help.

the pre unit 500's all had roller on drive side and ball races on the timing side.
the unit 350 's introduced in 1957 had a ball race on drive side and bronze plain bush on timing side.. the pre unit 500's carried on for another year or two
around 1959 onwards they used the 350 unit construction motor for their 500cc model (actually 490cc but who is counting)
About 1961 the T100A was introduced, which spawned a whole range ot T100nnn's
In 1968 the daytona 500's got a modified crankcase with roller on the drive side and a ball race on the timing side in place of the bush... Gradually this mod migrated to others in the 350/500 cc range.
To sum up, All bikes had at least one ball race somewhere ( to locate the crankshaft) and
a roller or plain bush on the other side. If a roller was fitted it would have been on the drive side because they can deal with greater side loadings than a ball race or bush. The plain bushes if fitted were always on the timing side. ( they also provided for the oil feed to the big ends)

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Panheahpollock

Thanks to you who answered the question. What I have decided was to have the crank built back up and cut back down for a standard journal size. This will prevent me from buying a crank that won't work with these cases. Evidently this is a mutt engine put together years ago. Thanks again and have a great day.