Frame Restoration

[Steve Little]

I decided to press it 3/4" passed the measurement I wanted.
Straighten 36-40 springer 016.JPG
Nope!! It just followed the ram back home.

Ok. I,m Freakin out... but I,m going to press it 1" passed the measurement I want.

I'm thinking...what the hell is going to happen.
This is my part, but I dont want to ruin it.
Its a genuine 1936-1940 keyhole springer.
They stopped making them you know!!

[ricmoran]

Steve, your on the right track, I have to say I'll bet your butt is puckering while your bending. Do you have another springer knocking about that is beyond help that possibly you could experiment with? That might help get to the correct over bend factor to arrive at the final set you seek.

[Steve Little]

Alhoa Ric. Thanks for the advice, and there was some of that going on.
You might have noticed from the pictures that originaly started work on another springer but switched to this earlier springer. A friend of mine wanted to repaint all the tinware on my 37 knuckle. So I let him and it looks so beautiful and shiny with this new paint job. But there is a draw back to putting lovely glossy paintwork on a bike that has been assembled for a while.... the rest of the bike now looks tardy. So now he wants to paint the springer and we are running out of good painting days as we scream toward winter over here. I dont have the energy to pull the whole front end off the bike at the moment, so I thought I would straighten this springer and give it to him for painting.

Back into the picture process:
I pressed it 1" past the measurment I wanted.... and supprisingly it made no difference
Straighten 36-40 springer 017.JPG
Straighten 36-40 springer 019.JPG
It eneded up moving at 1 3/8" (35mm) past the measurement I wanted.
If you are going to use my expieriece as a manual for your springer, I suggest a carefull approach like I have done. Dont assume that 1 3/8" will be right for your springer.

After releasing the ram and then measuring it, check out the vernia reading.
If there was such a thing as shed cam, you would have seen me do a little jig.... and then a a calming moment and then an air punch.

[Steve Little]

As I have written, I had very little first hand knowledge of working with Chrome Moly.
In an earlier post, I suggested that I was going to get a springer blasted so I could apply heat to the spears to aid in the straightening process.

A lot of people use the AMCA forum as a base for working on their projects and I must clear up that incorrect comment.
After I made this jig and set the first springer in the attachment, I felt under prepared with information to proceed with the job.
After my initial appeal for “springer straightening” information was met with deafening silence, I started a hunt for information in other avenues.

A reply from HD confirmed that the springers were straightened on the factory frame tables. And that Harley Davidson booklets that went with the HD straightening tables, are out in the world somewhere.

Also, I needed more information on the correct procedure for straightening Chrome Moly.
Ric, kindly advised me that it was going to be like herding a bunch of cats.
I only have one cat, and when I had a couple of attempts at herding him, he just sat down and looked away, indifferently.

I trawled through 5 or 6 forums that came up with a google search of “working with Chrome moly”.
There is plenty of information on Tig welding, brazing and tube benders for forming Chrome Moly, but I could not find one single reference to straightening a slightly bent tube.
I decided to resort to a phone call to a drag racing car manufacturer here in Australia for some first hand info. He advised me that when the nitro cars get a bout of shake, the frames get bent, (hate to think what it does to their bodies). So he does a lot of straightening.
He stressed that under no circumstance should we apply heat to Chrome moly to straighten a mis-alignment. Quote: “Heat will anneal the Chrome moly which is not the desired result. All adjustments must be done cold to maintain rigidity of the metal”
So, in conclusion, I wish to offer an apology for any bum steer I led anyone on. And to my cat for upsetting him.

[poorbiker]

Steve,
I have wondered more than a time or two if there is a calculation for how much over bend is necessary to straighten a bow or bend in various metals, cold. I once tried to straighten a 1/2" x 12" x 4` piece of cold roll that had a 1/16" bow in the middle of the plate. It finally took a little over 6" to remove the bow. I concluded it had to be the quickness with which the opposite force is applied (without heat) to effect change in the metal structures memory, I think requiring less over bending, travel. But I suppose that would be just another form of heat generated by quickly bending it, more of a quick hydraulic pressing. But I could be full of crap also.

[Steve Little]

Now that the spears have been brought back into correct alignment, I will ease my way into addressing the lack of forward sweep in the spears.

The picture below, shows the side view of the spears on my spare 1936-1940 fork.
It has been tampered with, or traumatised at some time in its past life.
Instead of a forward sweep, this fork actually has a negative sweep.
Straighten 36-40 springer 002.JPG
This next picture shows the height gauge set at the correct height of an inline axle.
It looks to be about 1/8” negative

Straighten 36-40 springer 003.JPG
I am going to use Kyle’s estimate of the forward sweep axle measurement, as I have no other information to use at this time.
I am getting up on my soap box now.
If any of you (100’s of peepers) have a good condition forward sweep fork, laying around, it would be very helpful if you could add some input on the measurement…or confirm Kyle’s measurement.
Keep in mind that this is probably the most information that has ever been written about these forks, so have some input.
When I get the time/energy to take the springer off my 37, I will measure it and add that to Kyle’s measurement.
The more measurement that we can garnish, the more accurate our accrued information can be.
There are an awful lot of these 1936-40 springers that have been straightened by a couple of very well known HD restorers in the US over the years, because they didn’t know any better.

Firstly, I established the measurement of the centre of the spindle by placing the height gauge on top of the rod. See picture. Then subtract half of the round bar to calculate the centre of the spindle.
Straighten 36-40 springer 005.JPG
Then I added Kyle’s measurement to the centre height of the spindle.
Then set the height gauge to that measurement.

The height gauge pointer indicates where the centre of the axle hole should be on a forward sweep fork.
The next step is to put the forward sweep back in the spears.

Straighten 36-40 springer 006.JPG
I have designed a couple more fixtures for this next operation.
The ram will be placed under the end of the spears to press them up.
I do not want to put all this upward pressure on the neck spindle, so I have drawn up some supports that will be bolted to the jig and hook over the top of the spears.
I will be able to support the top of the spear at any point along the jig and achieve a forming action at that point.
It may be a week before I can do any more work on the leg.
I ordered the steel yesterday.
I am having the plates profile cut and surface ground to make them look pretty and also, cut down on some of the machining time.
I’m getting sick of my own diatrab, so if anyone would like to chime in to add your experience of fork adjustment I would be happy to read it.
I will post more pictures when the fixtures are ready

[Steve Little]

Interesting Dave. I know that during the straightening of the right spear I was feeling pretty nervouse. But it was only because I had no experience. Next time I will move as cautiously, but will have the experience behind me. When we do a production run of bending tubes for the frames we make, I always check the first couple off the bender. If they are a degree out we make an adjustment on the bender and continue. I then put the effected tubes over a hard wood block and give a whack with my number 4 Thor leather hyde Hammer. If I give a whack within an hour it moves easily. If I leave it half a day before giving a whack I really have to belt it to take some of the set out. This is called work hardening and it takes the carbon in the steel a few hours to gather its witts, and realise its been bossed around....but when it does, its a stubborn bugger.

[Steve Little]

Even though I have ordered the material for the new fixtures for the jig, I decided to forge ahead on this job and use the equipment I already have.
I put the jig in the 100 ton hand press and supported the end of the spear and used the breadboard nylon to try and press the spear straight.
I brought the hand wheel adjuster down onto the spear with the nylon between the end of the ram and the spear.
I used the coarse pumping leaver to do 5 pumps, and on the sixth pump there was a loud bang and a whizzing noise past my ear, followed by a thump and clatter on the wall of the workshop.
I was thinking earlier on that a piece of ˝” thick nylon would be better.
I guess my saftey warning should read DO NOT USE 1/4" thick nylon on the leading egde of these springers during press work

Straighten 36-40 springer 002.JPG
I found a piece of nylon that is 1 inch thick and put that in between the ram and the spear.
I then hid behind the mainframe of the press while I pumped the lever.
Straighten 36-40 springer 003.JPG

[Steve Little]

I had checked the springer on my 37 before starting this procedure. After putting a small straight edge on the front of the spear in my 37 I could see that the 1936-40 spear is straight. When I put a straightedge on the 1941-46 spear it has a negative curve on the front face. When I straightened this spear it looked just like the one on my bike.

[Steve Little]

Not sure if this has actually been done on the forum before but here goes.
I set the 1941-46 rear leg on top of the 1936-1940 rear leg so that you can get a visual comparison.
The height gauge is only in there to support a rod in the axle hole of the top springer.
If you need me to explain the difference between the two leading edge shapes, let me know.

[Steve Little]

I picked up the material to manufacture the hook fixture this morning. It just needs the cap heads to be machined into it and a little cleanup and some radius on the corners, and then I can have a go at doing a bit more work on the spears.

Think it will be strong enough?.
What do you think? Spear straighten fixture 001.JPG.

Chunky.

The last picture is just sitting in sittu to show approximate working position.

[Steve Little]

machine ream 001.JPG
I ran a 1/2" machine reamer through each of the holes with my fingers to remove any paint or burrs.
Then parted off a peice of ground 1/2" silver steel.
This 1/2" silver steel can now be used to slide through the holes and be an accurate place to measure the height of each spear with a height gauge.

[Steve Little]

I hoped that the online presence of this springer project, might tease out some knowledge or information on this extremely vague subject.
Perhaps a springer blue print, or a HD springer straightening manual.
But not to be.
Aside from some well placed advice on cat herding, (albeit a little vague in technique) and Kyle’s (very helpful) advise on the forward sweep measurement, I was sure I could hear the occasional chirp of a cricket.

The hook attachments are tough and worked well. I used them in conjunction with the ram to straighten the 41-46 fork.

[exeric]

I appreciate what you're doing here Steve. I've straightened a few rigid forks and it is not easy. I used 7/16" ground drill rod in the fork stem to establish a center point, and drill rod in the rocker holes (like you have). I also made a fixture with the correct 3 hole pattern of the fork tubes and stem (same as the handlebar clamp). The only dimensions I've seen are the ones on the drawing of the rigid fork in the service manual. That drawing leaves a lot of dimensions undocumented and it makes you wonder if H-D wanted their dealers to just buy a new fork.

[Peter Cooke]

I appreciate it to Steve. I've been reading with much interest as I have a 31V with a slight reverse sweep in the left leg that will need straightening when I eventually get back to Oz and get started on it (currently in Spain until later this year at least). I don't know the measurements of it so don't know if it'll fit in your jigs but the method used should be the same. Once I pull it down I'll give it the once over with the vernier, straight edges, round bar, etc and maybe give you a call.