chassis recipe, introduction. - Page 5

vanzen · 10-19-2009, 01:24 PM

This time Pommie John's race bike:

The frame:

Detail of trans mount to frame connection and diagonal reinforcement of the rear frame cradle:

vanzen · 10-19-2009, 01:35 PM

Phreaky Phil's solution:

RecycledRS · 10-20-2009, 09:38 PM

Pommie John's machine is very interesting and the bracing he employees looks to be top notch. I like the addition of the diagonal braces from the main backbone tube to the swingarm area.

At first I thought that Preaky Phills use of the square tube to reinforce the head tube was over kill untill I saw the blue frame failure.

Questions:
Why does HPN use a supplimental bratcket around the swingarm pivot and would it help on a road/sports machine?
Are there any other HPN braces that may be appropiate?

vanzen · 10-21-2009, 12:33 PM

I'm not sure I like Phreaky Phil's method of the square tube brace –
A better route to take would be the Halenda / Kolb plate IMO.
Lighter, simpler, and more effective IMO.

Udo Gietl's BMW racers:

1973 BMW MotorSport-framed Butler & Smith Formula 750 Grand Prix.
Rider #17 was Justus Taylor from Vermont:

Reg Pridmore's ride, a 1974 version of the Rob North-framed F-750 GP bike:

The "model" for any successful stock Type-247 main-frame handling improvements
should be the modified 1976 R90S raced by Butler & Smith in the first season of AMA Superbike Class racing.
In that first season, the BMW team of Reg Pridmore, Steve McLaughlin and Gary Fisher dominated.
The AMA Superbike Class imposed strict frame modification limits,
and Udo Gietl bent them all "a little" to produce a race winner.
Gietl responded to the challenge with this excellent modified-stock frame solution:

Notice Gietl's anti-dive front suspension:

Pommie John's race-bike closely follows the frame modification tutorial introduced by Gietl,
and is, IMO, a fine execution of theory and construction methods.

87785 · 11-02-2009, 07:35 PM

Quote:

Originally Posted by shire2000

Anton, just for poops and giggles, How would you measure the change in spring rate?

I pulled out my old Physics books from Uni. and can't get my head around the concepts anymore. Been way too many years since I barely scraped thru those classes.

To measure the change in spring rates you could place a weight on the spring and measure the compression. Keep adding weight and each time you add weight, you measure the distance. Linear spring formula is F = Kx where F= force, K = spring constant and x = displacement. So, Divide the weight (force) by the compression distance (x) for each weight and when the ratio changes, you're discovered the displacement where the second spring rate or progressive nature of the spring kicks in.

RecycledRS · 11-02-2009, 09:03 PM

Any idea why the anti-dive front end on Gietl's bike (and a few others of the period) did not survive? It seems a very simple solution to the dive issue.

lostboy · 11-03-2009, 09:39 PM

The anti-dive linkage was actually developed by Todd Schuster, Udo's partner in crime. The parts are Cummins diesel rocker arms and pushrods!

Chris Hodgson had something similar on one of his street bikes, but he fabricated his from chrome-moly tubing.

rpeckham136133 · 11-05-2009, 07:53 PM

Man, the things you learn here....

Cummins diesel!

10-19-2009, 01:24 PM	#61
vanzen LuftKopfFlieger Join Date: Sep 2005 Location: Hidin' in the Hills Posts: 488	more images This time Pommie John's race bike: The frame: Detail of trans mount to frame connection and diagonal reinforcement of the rear frame cradle: __________________ "offerings to the god of speed" – painted on Burt Munro's work bench

10-19-2009, 01:35 PM	#62
vanzen LuftKopfFlieger Join Date: Sep 2005 Location: Hidin' in the Hills Posts: 488	another neck-stem strategy, images: Phreaky Phil's solution: __________________ "offerings to the god of speed" – painted on Burt Munro's work bench

10-21-2009, 12:33 PM	#64
vanzen LuftKopfFlieger Join Date: Sep 2005 Location: Hidin' in the Hills Posts: 488	comment I'm not sure I like Phreaky Phil's method of the square tube brace – A better route to take would be the Halenda / Kolb plate IMO. Lighter, simpler, and more effective IMO. Udo Gietl's BMW racers: 1973 BMW MotorSport-framed Butler & Smith Formula 750 Grand Prix. Rider #17 was Justus Taylor from Vermont: Reg Pridmore's ride, a 1974 version of the Rob North-framed F-750 GP bike: The "model" for any successful stock Type-247 main-frame handling improvements should be the modified 1976 R90S raced by Butler & Smith in the first season of AMA Superbike Class racing. In that first season, the BMW team of Reg Pridmore, Steve McLaughlin and Gary Fisher dominated. The AMA Superbike Class imposed strict frame modification limits, and Udo Gietl bent them all "a little" to produce a race winner. Gietl responded to the challenge with this excellent modified-stock frame solution: Notice Gietl's anti-dive front suspension: Pommie John's race-bike closely follows the frame modification tutorial introduced by Gietl, and is, IMO, a fine execution of theory and construction methods. __________________ "offerings to the god of speed" – painted on Burt Munro's work bench

11-05-2009, 07:53 PM	#68
rpeckham136133 bpeckm Join Date: Jan 2008 Location: Vero Beach FL Posts: 281	Man, the things you learn here.... Cummins diesel! __________________ bpeckm in Vero Beach FL 1966 R50/2 (gone but never forgotten) 1975 R60/6 gettin caffeinated 1981 monocafewannabee

10-20-2009, 09:38 PM	#63
RecycledRS Registered User Join Date: Dec 2008 Location: Vancouver Island, Canada Posts: 63	Pommie John's machine is very interesting and the bracing he employees looks to be top notch. I like the addition of the diagonal braces from the main backbone tube to the swingarm area. At first I thought that Preaky Phills use of the square tube to reinforce the head tube was over kill untill I saw the blue frame failure. Questions: Why does HPN use a supplimental bratcket around the swingarm pivot and would it help on a road/sports machine? Are there any other HPN braces that may be appropiate?

11-02-2009, 09:03 PM	#66
RecycledRS Registered User Join Date: Dec 2008 Location: Vancouver Island, Canada Posts: 63	Any idea why the anti-dive front end on Gietl's bike (and a few others of the period) did not survive? It seems a very simple solution to the dive issue.

11-03-2009, 09:39 PM	#67
lostboy Registered User Join Date: Sep 2007 Posts: 664	The anti-dive linkage was actually developed by Todd Schuster, Udo's partner in crime. The parts are Cummins diesel rocker arms and pushrods! Chris Hodgson had something similar on one of his street bikes, but he fabricated his from chrome-moly tubing.