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mark_weiss
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Arizona
Joined: 11/16/2013
Posts: 170

Near about ten years ago I was racing my R75/5. At the very right moment, just between turns six and seven, the transmission locked up. It was "the right moment" because the lockup occurred just at the point where I was fully upright between the two closely spaced turns. That meant not crashing. It's funny, all of the things that race through your mind when you realize that the rear wheel has locked and that squeezing in the clutch lever does not remedy the situation...

When I prepared to remove the gearbox, I ran across an unanticipated obstacle. I could not turn the driveshaft and therefore could not access all four of the driveshaft to transmision output shaft screws. One in particular proved to be unremovable. So, with nearly everything removed from the chassis, the bike sat for several years. When I finally decided that I would cut through the driveshaft and laid the bike on its side, I heard a clunk and found that the transmission was now free. Shortly thereafter the gearbox was out of the frame and I noted the curious sounds of metal objects falling about as I rotated the case. Also noted was a hole in the front of the case. That explained the distinct smell of gear oil that I recalled from when I had careened off of the track. Then everything sat for a while more as I contemplated something more serioius than a bent shift fork.

When I finally opened the gearbox I found that the pressed in shaft supporting the 2-3 shift fork had broken the boss away from the front of the transmission case, dropping the shaft and shift fork into the shafts. Instant lockup. Somehow it seems that I forgot to take photos. $300 worth of bearings, bushings, seals, a shift fork, a couple of gears, and a reconditioned gear case later, it is time to begin reassembly.

Considering that the bike had about twenty years of track use, there have been a few things to clean up along the way. It is not a restoration, but more of a rebuild. Who knows, it may even end up street legal.

  • 20170417_174011.jpg
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Mark
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Twocams
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VBMWMO #8750
Joined: 03/16/2014
Posts: 631
Why is the picture upside

Why is the picture upside down? More important why do you race these old bikes? And how...with other people on the track or...
I have never raced anything, well to any degree. Retired now but I used to work hard for my $$$ and never wanted to break anything I guess.

Richard

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Twocams
69 R69S 03 K1200GT
92 R100RT

mark_weiss
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Arizona
Joined: 11/16/2013
Posts: 170
I do not know why the image

I do not know why the image appears upside down. The original does not have that orientation. Hmm.

Why race? Because it is fun. I find racing to be a challenge which I enjoy and I like racing older machines for that challenge as well. Of course, my /5 was not nearly so old when I first pressed it into service. I've been racing on purpose built tracks, from Daytona to Willow Springs, normally grouped with others racing similar vintage and capacity machinery. Running with AHRMA, I raced in Sportsman 750. At CCS events, I fit in wherever I could: Vintage Heavyweight and sometimes Lightweight Superbike (running with modern bikes).

Racers don't want to break anything either.

The frame is powdercoated gloss grey. I removed unwanted brackets and filled unwanted holes.
The engine is fitted with a -336 sport cam. I checked its indexing as I installed a new cam chain.

A few more photos:

  • 20151201_161541.jpg
  • 20160106_173319.jpg
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Mark
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mark_weiss
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Arizona
Joined: 11/16/2013
Posts: 170
A shot from a race in

A shot from a race in Nevada.
Clearly, before the transmission implosion.

  • a_251.jpg
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Mark
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schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6327
Nothing like a good set of

Nothing like a good set of brakes for the track! Big Grin

I've not raced before, but I did stay at a Holiday Inn Express!! Actually, I attended a Keith Code class at College Station, TX, probably 23-24 years ago. I thought the discussions the night before about braking, weight transfer, etc., were well worth the cost. That sort of thing can translate to on-road riding if incorporated on a routine basis. The "chalk talk" helped the next day when I over-cooked a turn quite badly. I just kept pushing on the bars increasing my lean angle and amazingly, I spit out of the turn on the other side and had avoided the grass/gravel. I can still remember that exact situation all these years later...those 2-3 seconds seemed like a couple of minutes. It showed me there's more in the bike/tires than I would have thought.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

khittner
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VBMWMO #8223
Joined: 02/15/2012
Posts: 364
Tranny fell apart after 20

Tranny fell apart after 20 years of racing? Pretty good service. So much for the old saw about race bikes being "rebuilt after every few races", eh? Smile

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Konrad

Twocams
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Joined: 03/16/2014
Posts: 631
What is the big round black

What is the big round black thing under #407. Oil cooler?

twocams

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Twocams
69 R69S 03 K1200GT
92 R100RT

mark_weiss
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Arizona
Joined: 11/16/2013
Posts: 170
It is a fluids catch pan.

It is a fluids catch pan. Most racing organizations require some sort of fluid containment below the engine which should catch whatever exits the cases in the event of unexpected crankcase ventilation. Bikes with full fairings have it pretty easy, just enclose the lower portion. Those of us running machines that do not have bodywork need to be a bit more creative. My catch pan started life as a mailbox and could contain almost four quarts of liquid.

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Mark
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mark_weiss
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Arizona
Joined: 11/16/2013
Posts: 170
The top end was refreshed

The top end was refreshed every season. Usually just new rings and light cylinder de-glazing. Exhaust valves lasted three to four seasons. Big end rod bearings were replaced every two years. Main bearings? To the best of my knowledge they are still the original pieces. The last time that I checked clearances, they were still within factory spec. I did eat one final drive though. The pinion nut lock washer fractured and the nut backed off. The pinion pulled in a bit and took some teeth off of the crown wheel.

My Triumph, Norton, and Yamaha riding competition were often faster, but did not experience this level of reliabiltiy. At longer races I moved up more places due to others' mechanical failures than through overtaking.

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Mark
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