Where Have All The XAs Gone?

[Rockin Ronny O]

Hello everyone. I am in the midst of writing a book about the Harley-Davidson XA (shaft-drive) from WWII.

This is NOT going to be a "how to restore" book. Rather, it's going to chronicle where these XAs are today and how they got there. It's about the stories they tell.

So, I'm looking for owners of XAs, both private and museums, who would want to be part of the book. Photos, credits, stories, etc.! I already know where about 40 of them are, but where are the rest?

I would also like to devote a section to John Nowak of the Harley-Davidson Motor Company because as I understand it, he had a lot to do with the XA. So, if you know how I can get hold of his family, please let me know that as well.

I also host a discussion group about the XA on Yahoo.

Please contact me at:

Ron Ostarello
PO Box 632
Corning, CA 96021
(530) 824-9053
ebuyou@dm-tech.net
http://autos.groups.yahoo.com/group/XA-750/

P.S. You can see my XA at:

http://i19.photobucket.com/albums/b1...u/1b31db24.jpg
http://i19.photobucket.com/albums/b1...u/fb9bcd55.jpg

[Paquette]

Ronny--If you need any info on the XA saddlebags send me an e-mail. As I am sure you know, they were different than the WLA bags. I have an original and also a copy of the original production drawing.

[darrylri]

Ron, that's a beautiful bike! How close is the XA drivetrain to the BMW R71, upon which it's design is based?

I read an interview in the club magazine a while back with one of the Davidson's, where he said that the bike was pretty good and they considered putting it into production after the war, but just didn't find it necessary. I believe he also said that they made a pretty close copy because they could see that the Army specs were calling out for an R71, and unlike Indian, didn't want to put a lot of effort into it.

For comparison, here's a photo of an 80ish year old friend of mine on his 1939 BMW R71:

[Rockin Ronny O]

Paquette, I would love to have a copy of your copy of the saddle bag plans for the XA. What do I need to do to make that happen?

Nice photo of the R71! Looks like it was taken either around Tehachapi or Susuin. As for the drive train Darryl, I don't know what the Beemer has/had (other than a shaft-drive) but the XA's u-joints and shaft and plates, etc., were made by Mchs. Universal Joint Division. My problem is, I don't know what Mchs. is! That's the way it is written in the Parts Manual. Here's the service manual exploded view of the drive shaft:

http://i19.photobucket.com/albums/b1...DriveTrain.jpg

The XA was indeed based upon the BMW R71. It is also my understanding that the Russians based their M72 and the Chinese Chaing Jaing on the Beemer as well.

I also heard or read somewhere that SOME of the parts for all of those machines will interchange with each other! The heads come to mind.

Rockin' Ronny O!

[Paquette]

Ronny--Click on my profile and send me an e-mail or send one through my website.

[Rockin Ronny O]

Paquette, none of my e-mails seem to be reaching you. Neither your profile address nor your website address.

Here's mine:

ebuyou@dm-tech.net

Rockin' Ronny O!

[darrylri]

Ron, if you follow this link to John's Beemer Garage, you'll find a complete parts manual for the R71. Is there a parts manual for the XA on the web somewhere?

What kind of rear suspension does the XA have, that it requires 2 U-joints and the rubber disk? The Germans call that a Hardy disk, btw, and BMW used them from when they started with bikes in 1923 until 1956 when they went to a full rear swing arm. On the BMWs with a rigid tail, that was the only flexibility in the driveline. All the bikes with a plunger rear end, from 1937 to 1955, had a single U joint at the entrance to the final drive.

Yes, the photo was taken on Altamont Pass, heading west into the bay area. Joe Groeger had ridden his R71 from his home in Redwood City out to the NorCal BMW Club's 49er Rally in Auburn and back.

The Russian M72 and Chinese Chang Jiang were not "based" on the R71; they were built from the original tooling! Well, with upgrades over the years, but... During the war, BMW moved it's motorcycle production from Munich, where they were building aero engines, to Eisenach, where their car factory was relatively idle. After the war, Eisenach ended up in the eastern sector, and the Russians carried away the production line as a part of reparations. Hence the M72. In the 60s sometime, they sold it on to the Chinese. A lot of parts will interchange, though the difference can usually be told.

[Rockin Ronny O]

Darryl,

I have started posting the parts manual for the XA on my Yahoo discussion group. I have 17 of the 40+ pages listed in the photo section. It's at http://autos.groups.yahoo.com/group/XA-750 and you are invited to join the group (free) to have access to some interesting info and photos.

I always thought the rear suspension was similar to the BMW. Maybe there's more travel and that's why there's two u-joints in the drive shaft?

I wonder how the Indian 841 is set up?

Ron

[darrylri]

Originally posted by Rockin Ronny O
I have started posting the parts manual for the XA on my Yahoo discussion group. I have 17 of the 40+ pages listed in the photo section. It's at http://autos.groups.yahoo.com/group/XA-750 and you are invited to join the group (free) to have access to some interesting info and photos.

Ok, I signed up. Should be fascinating to compare how much of the motor and transmission are the same or similar.

I always thought the rear suspension was similar to the BMW. Maybe there's more travel and that's why there's two u-joints in the drive shaft?

Well, it does look similar on the outside... ;-) From the interview I mentioned before, it would seem that HD wasn't really very familiar with the BMW bike before reverse engineering it.

Is the generator on the XA similar to any other US bike generator? Did HD have to source it specifically for this model?

I noticed from a message on your board that the XA maintained the completely square bore and stroke of 78mm (well, 3 1/16" is ever so slightly less). Did Harley's other 45s have similar bore and stroke measurements?

[darrylri]

Well, I thought I'd add another link here. Check out Duane Ausherman's web site, where he has an English language brochure for the 1939 line of BMWs, which includes the R71. I'd be very interested to hear about what's similar and what's different between this and the XA.

[Perry Ruiter]

The 841's drive shaft has a u-joint at either end, just like the XA. In terms of generator, the XA used what was essentially a Harley 32E generator. Different drive gear of course and a minor tweak to the housing to shift the oil drain hole (90 degrees if I recall correctly) ... Perry

[darrylri]

Originally posted by Perry Ruiter
In terms of generator, the XA used what was essentially a Harley 32E generator. Different drive gear of course and a minor tweak to the housing to shift the oil drain hole (90 degrees if I recall correctly)

Err, oil drain hole? The XA runs engine oil through the generator? Is that typical of Harleys? (It must be obvious by now that I know nearly nothing about HDs.)

[darrylri]

I was looking at the parts book that's up on the XA group web site, and the photos that Rockin Ronnie took of his bike as he dismantled it and restored it.

I think I understand why the XA has 2 U joints on its shaft. The final drive isn't in the same plane as the transmission output flange. On all of the BMWs, the two pieces line up, and the driveshaft only has to rise or fall with the motion of the plunger suspension.

I noticed that the XA calls for 4.00x18 tires. The R71 takes 3.50x19, which I think are narrower.

One thing I didn't notice on the XA was the spacers on the two motor mounting studs, between the motor and the left lower frame rail, that the R71 has. All of the BMW bikes have the motor and transmission positioned somewhat to the right of the centerline of the bike -- until they went to a 3 shaft transmission in 1970 -- so that the driveline is straight from the transmission output to the final drive input.

Perhaps Harley (and Indian?) didn't want to move the motor over enough to make room for the wider tires, and the 2nd U joint solved the problem.

[Perry Ruiter]

Err, oil drain hole? The XA runs engine oil through the generator? Is that typical of Harleys? (It must be obvious by now that I know nearly nothing about HDs.)

Yes, most 32Es have a small oil drain hole at their lowest point to allow gravity to drain any oil that might make it past the shield, bearing and seal (still a felt seal until after the war). Since the generator was rotated slightly to mount on the XA, the oil drain hole was also moved to keep it at the lowest point ... Perry

[darrylri]

Originally posted by Perry Ruiter

Yes, most 32Es have a small oil drain hole at their lowest point to allow gravity to drain any oil that might make it past the shield, bearing and seal (still a felt seal until after the war). Since the generator was rotated slightly to mount on the XA, the oil drain hole was also moved to keep it at the lowest point ... Perry

Ah! I would wish for that arrangement on my R12.

The R71 has a sealed Bosch generator clamped to the outside of the motor. The face of the generator, along with a cork gasket, seals the hole in the crankcase where its input shaft, and the gear that is driven from the camshaft, enters. No oil is supposed to transfer into the generator.

My R12 has a similar setup, but has a thin spring that is supposed to hold a shield against a cork gasket and then against a large crankcase openning. There's also a felt seal between the shield and the input shaft. Perhaps because the pistons and bores were well worn and there was significant blowby, it leaked at this point. I hope to find out in a few months that this is now fixed... ;-)