Early pacemaker gearbox.

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Ihateyoubutler
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Sun Apr 12, 2009 7:57 pm

Probably a daft question (so please don't ask me why I asked it),but is there any way that an early pacemaker gearbox can be used in a tuned engine? I.e. using a different third gear? I understand this is the weak point?
Thanks.

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byron
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Sun Apr 12, 2009 8:00 pm

hope so, I got another 39 tooth third gear cog [new marked innocenti from Scooter Restorations] and plan to fit this in my 240 build. the difference in the the thickness of the teeth compared to the original is very noticeable.

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byron
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Sun Apr 12, 2009 8:01 pm

also see this thread

Ihateyoubutler
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Sun Apr 12, 2009 8:17 pm

So, are you saying that by replacing third gear from ,say a 39 tooth sx150 gearbox, this will solve the potential problem?
Thanks.

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byron
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Sun Apr 12, 2009 8:24 pm

Ihateyoubutler wrote:So, are you saying that by replacing third gear from ,say a 39 tooth sx150 gearbox, this will solve the potential problem?
Thanks.
no, it needs to be a [later] pacemaker loose gear.
the SX150 third gear eg, although it has 39 teeth it is a larger diameter as the corresponding group cluster has less teeth.

mickyb
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Sun Apr 12, 2009 11:00 pm

I use the early box in my Mugello 225, no problems. You cant use the later 3rd gear with the early type xmas tree though

J1MS
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Sun Apr 12, 2009 11:38 pm

I like the pacemaker gear box, The gear ratios make for a nice close ratio from 3rd to 4th and the later gear boxes are very tough.....The early ones were claimed to have a habit of snapping the weaker 3rd gear, but not just the gear the mainshaft was also known to break, the mainshaft design was also altered on the later gearbox's.....But there not as bad as some people make out..... IMO.

If they are to be used, even in a mildly tuned 200 engine, and not downshifted from 3rd to 4th violently from high speeds, they can last a long time and can be very cheap as no one seems to want them....and If they were so breakable why are there so many still available some 40 plus years since they stopped making them.... IMO one of the best sets of gear ratios for a rev happy engine...... just ride it like you own it not stole it.....

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byron
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Mon Apr 13, 2009 12:08 am

mickyb wrote: You cant use the later 3rd gear with the early type xmas tree though
why not ? I haven't put the gearbox together yet, was planning to do a dry build in a spare case. i was possibly expecting to have to fettle a little to get everything meshing nicely. but am I heading down a dead end ??

J1MS
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Mon Apr 13, 2009 12:15 am

^^From memory Its a different fit, it dosnt mesh properly^^

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byron
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Mon Apr 13, 2009 1:42 am

J1MS wrote:^^From memory Its a different fit, it dosnt mesh properly^^
oh pants :(
thanks, saves me some faffing about...

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