/2 reverse conversion. Driveshaft fun

[robert]

I too was trying to figure out why.

Why? Turning a vision of something you want into mechanical reality is reason enough.
I have built a few things that I am sure some have asked the same question. I wish I had
an answer to the driveshaft question, but I don't.

[Izzypwc]

Nice one Robert. Thought it was a strange question myself. Similar question I got when I built my Manx norton for road use...The answer is always "why not". I'll keep you guys posted on the build. Pictures tomorrow night.

[George Ryals]

There is discussion and pictures on "slash2conversion" yahoo group. Join the group and search for "reverse conversion" I believe the drive shaft question is answered.

[mattcfish]

Correct...rennsport replica in the making! I have a great hose tank and killer seat to match. Just need some help on the driveline. Thanks guys.

OK, but the /5 frame, is that similar to a Rennsport? Forgive me, I'm all for creativity and whimsy. Just curious about the project. I would personally give it more grunt though, since we're not trying to build a blue print of the original.

[Major Softie]

OK, but the /5 frame, is that similar to a Rennsport?

Well, the Rennsport had a swingarm suspension like the /5, but leading link fork.

[mattcfish]

OK, but the /5 frame, is that similar to a Rennsport?

Well, the Rennsport had a swingarm suspension like the /5, but leading link fork.

Motorcycle: BMW 500 Rennsport Manufacturer: BMW, Munich Type: Racing Year: 1954
Engine: BMW two-cylinder, opposed-piston, 180°. Four-stroke cycle. Double overhead single-shaft distribution, with bevel gear shaft. Direct injection with Bosch pump. Displacement 493.9 cc. (68 mm. x 68 mm.)
Cooling: Air
Transmission: Four-speed block. Final transmission by cardanic shaft
Power: About 60 h.p. at 9,500 r.p.m.
Maximum speed: About 143 m.p.h.!
Chassis: Continuous, double cradle. Front wheel, Earles suspension; rear, telescopic shock absorbers
Brakes: Front and rear, central drum

That would be quite a wild ride. Are you going to fuel inject it?
Supposedly the bike only weighed 275 Lbs. Where was the weight taken off?

[Major Softie]

Supposedly the bike only weighed 275 Lbs. Where was the weight taken off?

Some things are obvious:
Subframe
Battery
Air Cleaner and housing
Headlight nacelle
Alloy tank
Lighter hubs and rims
Lighter frame tubing

But, that would only get a portion of the claimed weight loss. Like any factory race bike, I'm sure they shaved ounces everywhere they could, but I don't know how they got down to that claimed weight. Course they probably lost about 20 lbs of flywheel.

[Deleted User 62]

Check out where the engine mounting bolts are, looks like forward and up from the stock location:

[Izzypwc]

I'm glad you guys are getting pumped up about this project! I'll send pics on the weekend. In the meantime, any ideas re driveshaft. The yahoo group guys only seem to care about true comversions instead of this "reverse conversion".

[mattcfish]

I'm glad you guys are getting pumped up about this project! I'll send pics on the weekend. In the meantime, any ideas re driveshaft. The yahoo group guys only seem to care about true comversions instead of this "reverse conversion".

rg-mc-72-67.jpg (250.07 KiB) Viewed 998 times

Looking at the pics, it's a dry shaft running into the swing arm tube. No boot? That makes since because the /2 shaft runs dry. /5 shafts can run dry too with a little grease now and again. To make the /5 swing arm look more period, you would remove the portion of the shaft tube flange for the rubber boot. This would give you lots more clearance to work with. Not sure what the Rennsport uses to keep crud out of the tube, there must be some kind of dust seal. If the /5 shaft won't bolt to the /2 tranny (or vise versa) then weld a /2 front shaft to a /5 rear shaft. If that isn't the issue then shorten or lengthen the /5 shaft to the proper size. You'll need a good fabricator who can make a strong and straight shaft out of it. This may not be that uncommon, since many of today's hot rods use front wheel drive half shafts that need modification for racing (or just being fast and furious).