1968 XLR??

Classic short-frame models

Re: 1968 XLR??

Postby mikeslemmon » Thu Mar 16, 2017 11:06 am

re: swingarm bearings is it preload or resistance.1 to 2 lbs. ?
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Re: 1968 XLR??

Postby thefrenchowl » Thu Mar 16, 2017 11:45 am

You tighten them nuts, find a spring scale, hook it to the arm and lift up.

The swing arm shouldn't move up until you read 1 to 2 lbs on the scale...

Patrick
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Re: 1968 XLR??

Postby mikeslemmon » Thu Mar 16, 2017 12:00 pm

the factory service rep. told me the R,s were set up with 100 Lbs. torque on the through bolt and the outer race nuts but that makes the swingarm weight without the added weight about 0 (I hope this makes sense } .
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Re: 1968 XLR??

Postby thefrenchowl » Thu Mar 16, 2017 12:14 pm

The through bolt doesn't interfere with the Timken pre load...
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Re: 1968 XLR??

Postby mikeslemmon » Thu Mar 16, 2017 2:02 pm

.the through bolt torque is .mostlikely to keep the pressure between the hole and the bolt .low under acceleration and braking
.
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Re: 1968 XLR??

Postby dr dick » Fri Mar 17, 2017 9:27 pm

9 screw cases vs 10 screw cases:
all r cases thru 69 were 10 screw.
these use the r castings.
not all r thru 69 had 10 screw covers
seems to be the 10 screw covers were depleted around mid 68?
in other words ther were 10 screw cases fitted with 9 screw covers from the factory.

in 70 there were two case castings:
the orig r set used on early xr that year.
(and maybe on the few xlr's built?? the 70 xlr is so rare its speculative as to what parts were fitted. i consider them "custom builds" with what was available at the time. i think there were only around 10 units made).
or
the late 70 thru stud xr motors.
these used a modded casting based the production sporster 9 screw cases.
the right case had added meat where the right side exhaust quadrant stud attached at base flange.
this 'new' 9 screw case set was supplied as parts dept replacement for earlier xlr, albeit, drilled for the orig 900 base stud pattern.

this 'new' cas set was also used for the 72 xr.
and in 75, 77, 80 with the sump machining added.
i belive in 83 the cases change again, most easily noticeable difference being no provision for kick starter.
after the 83 vintage i have no idea what happened.
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Re: 1968 XLR??

Postby thefrenchowl » Sat Mar 18, 2017 6:23 am

Hi DD

This part shot:

Image

of Pohlman # HD 29919, filed 16 Dec 1968:

Image

XLRTT with 10 screw locations tin cover, 9 screws only and a blanking bolt on the tool box thread makes me think this is the start of the new race cases based on 57XL patterns.

Patrick
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Re: 1968 XLR??

Postby sportsterpaul » Sat Mar 18, 2017 7:33 am

I note there is no smaller screw at the bottom of the cover. I guess in the mad rush to get the bike ready for pictures, they couldn't find anything other than the 1/4-20 screws. This warns me that these pictures are of engineering prototypes and not factory production, so once again, we can only guess at what the haphazard and arbitrary things the Factory was doing 60 years ago.
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Re: 1968 XLR??

Postby thefrenchowl » Sat Mar 18, 2017 8:17 am

Yes Paul,

But there's a wide span between educated guess and wild unsubstanciated guesses. Above, I give you 2 reasonable observations for my belief.

They might have rushed the assembly for the photo, but the rest of the engine, we can safely assume, was machined properly and not gone over with a bench drill, a hammer and some bent spanners...

Now, if you assume like I do that about 250 XLRTTs were ever build in a 12 year span, yes indeed, theses are NOT factory production!!!!

I've been looking at these racers since 1969, one tend to get a feel for what was going on there...

Now, you don't have to believe me, but you then have to come out with better proof to state that the factory race dept was doing haphazard and arbitrary things...

They were not...

Patrick
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Re: 1968 XLR??

Postby sportsterpaul » Sat Mar 18, 2017 10:03 am

...you then have to come out with better proof to state that the factory race dept was doing haphazard and arbitrary things...

But but but-- is it not you own website that publishes the Jesse OBrian story, brother of the race manager at Harley in those early years? He made it sound pretty haphazard to me. So did Jerry Branch when he told me how he begged the race group to dyno a set of cast iron heads he welded with with his small-ports flat-piston theory. After nine months they did finally do it can called him asking for 20 sets.

This in no way is meant to trash the great reputation of the race group. Branch also told me how the XR-1000 was a gauntlet thrown down by the race group when they objected to Porsche designing the Evo motor. According to Jerry, the production guys said "If you guys can design an aluminum head in 9 months, go right ahead." That's exactly what the race guys did. It is a shame that corporate group-think made the XR-1000 an option instead of the standard 1983 head, and that they killed it instead of letting the Porsche design be only for big-bikes.

I'm just saying we can only guess what was going through their minds, or what they were building, but I gladly concede that experts like you are far more "in their heads" than anyone else before or since. I will say that it sure looks like Harley engineering and documentation would be laughed out of Detroit, based on my working at GMC Truck and Ford. Dave Hennessy gave a great insight when he commented how broke Harley was in 1950s. The 1950s are when Indian went under, after all. And so Harley would weld up frames or slap last-years parts on bikes if it was cheaper. We can guess what they were doing, but they never bothered to write a lot down. If Harley would release the ECOs (engineering change orders) we could see why the did things, but many of them might say "cost reduction" like when I was in the auto business, and they would be rightfully embarrassed.
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