1941 Bent frame

[flat-happy]

mine has the riveted crossbar. it is broken off but the rivets are still there. the original motor was a 40EL34++ vin

[Steve Little]

Hi Flat Happy.
Does your reply mean that you have the standard 1940 frame with a rivited toolbox crossbrace or that you have the "Bent frame" with it.
Regards Steve

[flat-happy]

it is a bent frame---i'll try posting pix

[flat-happy]

it is a bent frame---i'll try posting pix

[flat-happy]

it has a slight bend in the backbone but didn't show up very good in the picture. it was hard to photograph on the top shelf in the warehouse. i bought this frame in wauseon last weekend and it's now last in line!!!

[Steve Little]

Hi FlatHappy.
Your frame looks a little different. The backbone of your frame does not look to have the dogleg bend in the backbone like we have been discussing. I will try and post some pictures.

[Jerry Wieland]

Steve

Flats frame would make sense if this one was bent after it was fabricated. Ones like mine were definitely made up with the bent parts. That bend looks very good and feasible after the fact.

Jerry

[RichO]

bent

Jerry, your top backbone bar looks like mine (slight bow) but my legs are bowed out ever so slightly unlike the other two frames pictured. If the top bar was bowed down to rake the bottom of the neck out wouldn't the legs be slightly bowed out than in? Physics. I still can't get my head around the 25 degree thing and iI didn't get it from Palmer but my own experience.

[Rollo]

1941 bent frame

Steve,

Tom Hardy here in Virginia. I saw this thread and have read it with great interest since you built me a 41 frame for my 41 knuckle sidecar rig that had a broken frame. I just went out to the garage and checked it out. The frame that the bike came in is a 41 "bent frame" based on the pics I have seen posted hear. Mine has a very slight bump/bend in the top tube and my down tubes have what appears to be a gentle curve from the neck down to the side car loops. It is a very early production number 41 EL 1177 and my other 41 is even earlier 41 EL 1109. I was planning to build it in a "restored" frame I bought that is, as of now I would say is a late 41 or 42 to 46 frame. As I told you when I bought the frame from you I have a ton of money in that frame and now appears that is is techincally not correct for that early a 41 production number. It is feasible to do this "bent frame" correction or to reevaluate and spend the bucks to restore the broken frame. I had planned on fixing it but for another project involving a 40 flathead motor. I will be interested to see where this thread goes and if anything definitive is decided.

Tom (Rollo) Hardy AMCA # 12766

[knuckleheadtim]

Steve Little- From where do you get the 25 degree figure? I've repaired numerous frames, and they are all 28, 29 or 30 degrees rake as the Palmer manual states. You had me scratching my head, so I measured again and I still get 28 degrees???

Tim

[RichO]

bent

Thank you Tim, me too. 28 till '40, 29 till (help me here) late knuck then 30 for Pan and or late knuck?

[Steve Little]

Hi.
Jerry... are you thinking FlatHappy's frame is one of the dealer altered 1940 frames or do you think these ran in conjunction with the Factory "bent frames" in 1941?

Richo and Knuckleheadtim
You may or may not know that I manufacture Big Twin HD frames from 1937 to 1966. I have a passion for all things correct on these frames and have a need to know everything about every frame in that period....I have a large accurate data base for most of these frames but I have a grey area on these "bent frames" hence the starting of this particular thread.
I am always on the hunt for the most concise information I can get, to add to my records.
I know the Palmers book is wrong because I have a copy of Original HD drawing 111-3E. This is a original HD drawing first dated 7-10-36 and has revisions dated through to 3-9-1938.
I started as a HD frame restoration business in Dec 1989. I have had the opportunity over last 20 years to buy
wrecked frames and have used all these original components to give to my pattern maker to use as the measurment for my patterns.
These frames up to 1940, will not go to 28 degrees without bending/ bowing the downtubes and Backbone.

Aside from this "Bent frame" that we are discussing, the backbone and down tubes on a original frame should be perfectly straight. Easily checked with a 12"rule
There are exact measurements and angles in degrees and minutes for downtube and backbone angles etc
For those of you with toolroom, Engineering or Drafting experience, there is an exact measurement/datum point from center of the seatpost cluster to centre of steering neck, down tubes to sidecar lugs etc that when calculated with Cos Sin and Tan are used to an exact computation.
Besides the drawing clearly stating 25 degrees, using all these comptations on this drawing, the 1936 to 1940 necks calculate to 25 degrees. They were designed, Drawn and manufactured as 25 degrees
These 1936 to 1940 necks will NOT assemble at 28 degrees.
I was told by an old contributor to this forum "Fiskis" that Bruce Palmer had revised these 1936 to 1940 frames to 26 degrees in some Army book that he had published after the "How to restore" book. This is still wrong but much closer.
Please note that I think the Bruce Palmer "How to Restore" book is a marvelous book, but on this particular reference he got it wrong, and it makes a headache for me when 99% of people treat that book as gospel in this instance, and customers are trying to order these frames or necks expecting 28 degrees.
Regards Steve Little

[knuckleheadtim]

I don't see where you get 25 degrees. I get 28 from the stem to vertical on everything I measure.

Tim

[Steve Little]

Tim.
What you are not taking into account with your protractor is the particular uniqueness of the 1936 to 1940 springer front ends which is quite different to 1941 to 46 inline springers
Regards Steve

[bmh]

Steve, What is the difference on the early springers? If the stem and legs are inline than the rake of the front end and the rake of the frame steering head are the same. While I believe that the triangulations on the blueprint work to 25 degrees, I wonder does it match with the dynamic ride height center line? ie. a level line drawn through the chassis front to rear, usually axle center to axle center( assuming rolling diameters are the same front and rear as they are here of course)? Rake and trail are not the sum of any one part, be it the frame or the front end.