53KR in a Low Boy Frame

Racing K Models

Re: 53KR in a Low Boy Frame

Postby Ferrous_Head » Sat Oct 31, 2020 12:18 am

Better tubing, better fabrication techniques, better welders?


And this may well be the case.

I just think far too many people think building the lightest bike possible is the way to instant success.

That chro-mo frames and alloy fenders are what differentiates a 1st place bike from an also ran.

The top factory bikes in "production" racing are always going to be built regardless of expense or with the object of using the bike for many years. I suggest this is why KR's had "special" frames and did not use production K frames.

You have to give the buyers of the "race" bikes something extra for their money or they might as well race a stock bike.

Also, hardly makes any difference when the rider weighs in over 200 lbs.
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Re: 53KR in a Low Boy Frame

Postby DaveAus » Sat Oct 31, 2020 1:49 am

hugoct wrote:Dave you can run a Sportster rear brake with the XR swingarm. Gordon Campbell makes a beautiful replica of the KRTT rear brake with the bigger shoes and finned hub.


Thanks Hugoct. I’d like to use the XR swingarm if I can. Does Gordon have a website I can have a look at?

Regards
Dave
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Re: 53KR in a Low Boy Frame

Postby 44UL » Sat Oct 31, 2020 2:20 am

OK thank you for what I am taking as definitive information on KR frames. I only questioned the chromoly aspect from the fragile WR frames and what i have seen of sole KR rear sections and i assumed it was a welding/construction issue which we have figured out over time since chromoly has been used in many forms of motorcycle and automotive racing frames/chassis.

Possibly my resistance is because after buying not one but two ‘53 K frames to put my ‘62 KR in I didn’t want to accept that it’s still not totally right...
62 KR, 56 KH, 56 KHK, 53 K, 47 Servicar, 44 UL, 48 UL, 48 WL race bike(40 rwhp) 51 WR, 68 XLCH, 38 EL, 65 Topper,
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Re: 53KR in a Low Boy Frame

Postby raleypc » Sat Oct 31, 2020 8:45 am

When you substitute the same size chrome moly tubing for carbon steel tubing, the weight and stiffness are identical. The difference is that the chrome moly tubing has a higher yield and tensile strength. If you use thinner wall chrome moly tubing it could be both lighter and less stiff while maintaining the strength capabilities of the heavier carbon steel frame.
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Re: 53KR in a Low Boy Frame

Postby hugoct » Sat Oct 31, 2020 12:18 pm

The KR frames beginning with the 1954 model year production of 52R frames ( rake 26.30/24.30) are dimensionally different than the counterpart K frame (rake 28.30/26.30). The change in geometry was made after much trial and error testing a lot of it done by Paul Goldsmith. The tubing isn't the big piece it is the steering head either cut re angled with less rake and welded (54-56) (47099-53R) or the 57R casting. At the time of the angle change the triple clamps were changed from non parallel to parallel. A standard K frame does not turn very well on a race bike.
Last edited by hugoct on Sun Nov 01, 2020 11:31 am, edited 2 times in total.
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Re: 53KR in a Low Boy Frame

Postby hugoct » Sat Oct 31, 2020 9:05 pm

Ottis Campbell on Facebook makes the brake.
Jeff Willis at [email protected] makes the 57R steering head and the lower frame rail footpeg mount.
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Re: 53KR in a Low Boy Frame

Postby JerrryR » Sun Nov 01, 2020 10:46 am

Hi all, I apologize in advance for jumping in on this thread with a question about a frame I have, I figure if any group could answer my question it's you guys. A number of years back I bought a K racing frame at Davenport Iowa from a vendor. He said he got it from his friend who was a racer. He told me the racing friend was Al Burke. He also told me the factory built this frame specially for him. What is unique about it is the backbone and the legs between the front neck casting and the rear tomahawk are not tubes but rather solid bar stock. The rear downtubes are tubes. The frame weighs about 36 pounds. I have attached pictures. Since I can only do 3 pictures I will post a second time with additional pictures. Bottom line my question is, is this frame legitimate or is it BS? One of the pictures I will post is an article I found about Al Burkes racing carrier. The article mentions that the factory had built special frames for him. Apparently there is something unique about racing the short track as relates to a frame? Thanks in advance for any of your thoughts about this,
JerryR

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Re: 53KR in a Low Boy Frame

Postby JerrryR » Sun Nov 01, 2020 11:09 am

Al Burke frame Continued. I did ask about this a few years ago but I thought there may be some new folks on the site with opinions now.

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Al Burke 1.JPG
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Al Burke 2.JPG
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Re: 53KR in a Low Boy Frame

Postby hugoct » Sun Nov 01, 2020 4:39 pm

If one pursues the 50's period AMA Rule books one will quickly see that racing frames could not be modified from the manufacturer's as delivered specifications. Harley had to send blue prints to the AMA to get two holes drilled in the KR frame for mounting the 125 tank approved.
Regarding Mr. Burke's bio if one examines the list of AMA sanctioned races for July 1956 one will discover a very different landscape.
There is no half mile in Iowa, there is no short track in Milwaukee, there is no short track in Flint, Michigan and there is no racing at Schereville, Indiana.
Regarding the previous owner of the frame's representations regarding provenance, claims of provenance for motorcycles and parts for sale at swap meets are ubiquitous. The representations are not even first person. Unless there is documentation (factory blueprints, factory correspondence, period photos, AMA Referee Bulletins regarding the approval of optional equipment) any representations should be looked at with Ronald Regan's advice in mind, "Trust but verify".
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Re: 53KR in a Low Boy Frame

Postby Ferrous_Head » Sun Nov 01, 2020 5:19 pm

I suspect a lot of people made or had made custom frames and other parts. I have no idea if anything like this ever left the factory or if it did, was it a "special order" that went out the back door ?

To my own discredit, Brad Andres offered to sell me some parts about 25 years ago, which I did not buy. To be fair, I'm in Australia and the costs of the parts plus shipping was going to be $2-3,000 (AUD) and at the time it seemed like too much money for a bike that would not be able to win a race in Australia. (Well, I would have built it into a bike).

What he had was the frame, shocks, rear brake (finned one) tank, oil tank and fairing.

But Brad told me the frame was built for his Dad somewhere in Chicago he believed. I might have a copy of the "conversation" I had with him at the time. I would have to search for it. I have no reason to doubt I was talking to Brad Andres though and all of the parts apart from the frame looked very much like genuine KR stuff.

The frame

Image


Top of the (big) tank

Image


To this day I kick myself gor not having bought these parts.
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