Hitchcocks Forum

can anybody help with ideas/suggestion to replace the orignal parts that are no longer available regards chas

Hi, do you have the original parts? They appear to be a just a steel washer! On my flying flea I replaced the outer bearings with a sealed one(with the inside seal open to lubricate the bearing) this worked ok! Vince

vince wrote: ↑

Sat May 30, 2020 7:09 am

Hi, do you have the original parts? They appear to be a just a steel washer! On my flying flea I replaced the outer bearings with a sealed one(with the inside seal open to lubricate the bearing) this worked ok! Vince

I have long wondered why they don't do this on 2-t motors after watching a mate do his "everlasting wheel bearing" trick which involved pulling the inner seals off the bearings, installing the first one and the spacer tube, filling the space round the tube with grease, then installing the second one.

I assumed maybe the combination of heat and fluctuating pressure in the engine was too much for the seals or they needed some degree of circulation through the bearing. Or indeed, why not totally sealed bearings? You'll throw a sealed bearing in a huge roller in a paper mill then run it at high speed and load all day, every day for 2 years. Some old jawas had a centre main bearing that needed greasing every few hundred miles through a nipple on the front of the engine. (NB: I'm not suggesting this, just idly wondering why not.)

Did you go for a metal or rubber seal?

I don't know about the Prince engine, but on the MZ 250 two strokes, depending on year, the mains were either lubricated from the gearbox oil or on later premix ones, via a passageway to a space between the bearing and the crank seal.

I knew the Jawas had a centre bearing, didn't know you had to grease it though!

Frank

Hi, I used rubber seals as they were handy but I would imagine either type will work. On the flying flea the original seals are just a bush so fitted the bearings as an extra. Vince

I didn’t need to grease the centre bearing on my 350 Jawa either - a late seventies oilmaster version. IIRC it was the 250cc CZ twin that had this need/ facility.

I think it was a Jawa model 623 that had a central grease nipple, I had a scrap engine off one once that I robbed the gearbox out of... But I'm leading us way off topic here.

The Prince originally had lipped seals (and could be retro-fitted to earlier Ensigns and RE2s). A number of years ago these were difficult to obtain. I was lucky to find some new/old stock at the time but if you have an original it might be worth touting it around bearing factors (one lock-down permits) to see if there is a suitable alternative

Further to my earlier reply, I have raked through my memory and notes and can now be a bit more specific. The drive side lipped seal was part no. 40686 and the drive side nut just behind the clutch ran inside the seal. The flywheel side seal was smaller - part no. 39304 and ran directly on the timing side shaft.

thanks for all replies great information ! . regards chas