Frame Restoration

[Steve Little]

There are people making/selling replacement tubes for the front spring fork.
Anybody know what material these people are using.... chrome moly or mild steel?

[larry]

Purging the tube with argon during welding will make the inside look as good as the outside, and make the weld stronger by eliminating oxidation in the root.

[Steve Little]

Purging the tube with argon during welding will make the inside look as good as the outside, and make the weld stronger by eliminating oxidation in the root.

Hi Larry. Do you have experience with helium as well?
Out of curiosity, I'd like to read a comparison on the 2 shielding gasses.

[larry]

I've only used argon.

[harleytoprock]

Since it is chrome moly, would it be a good idea to stress relieve the welded area by heating red hot with acet torch and back off slowly for a slow cool?

[Steve Little]

Larry. I had better watch my P’s and Q’s with another metal worker looking over my shoulder.

Toprock. (stress relieve the welded area by heating red hot with acet torch and back off slowly for a slow cool)
I don’t feel qualified to answer your question. I had to ask questions from a drag race, car frame builder about straightening techniques on chrome moly.
Tempering and case hardening was a subject that we were taught as apprentices, but in a limited (intorductory) sense.
Heat treatment of steel is a Trade/skill on its own, and the Tradesman I knew that was skilled in it, had an opportunity to work in that field for a while.
My skill set in this field is restricted to hardening the tips of my cold chisels when they get soft. And in my metal working days I have used heat contraction, to straighten the bends that truck drivers chains had put in 10” flange X 2 foot high X 40 foot long beams. I did this with heat, but your question is out of my experience.
Also, I am not sure if you are asking a general question or you feel qualified to post this as part of the procedure? Can you clarify that?
As a safety measure, I might have a poke around on the web and see what I can find.
My internet is a bit slow today for some reason so I will try and load pictures of the next steps later on.

[Steve Little]

Next item on the agenda was the cracked spacer in the stem crown.
Springer weld repair 006.JPG
Firstly, I had to remove all brass from the area.
I did this with the 2 burrs sitting beside the die grinder. Then used a flap wheel to finish it off.
Then I had to find the bottom of this crack. I decided to use the pointy tip burr to open the crack right up.
I decided on an open style of weld prep because it is such a narrow section and I want to be sure to get a good weld in.
I think this section cracked after the leg broke. Due the flexing of the unsupported lower leg

Before I had repaired the leg, I could grab the bottom of the leg and move it about, quite easily.
After welding the leg, I haven’t a hope in hell of moving it. The spring crown looks spindly, but the combination of all the components welded together gives a nice rigid effect to the leg.

[Steve Little]

I had a bit a feel around inside this spacer with a bit of wire and it feels like it is made of two chanel sections facing each other with a gap of about 3/16” or ¼” between the two.
The end of this chanel section must have had the flanges cut away so that it could be wrapped around the leg.
Robbie, was it you who posted a picture of a sectioned spinger crown a while back?
If so, does it show this area?

[Steve Little]

As I wrote before, a clean surface in an area like this does not gaurentee a good weld.
As I was laying the first run, it started well, but pretty quickly the flame turned from white to Green. This was the braze material sucking in from behind the chanel, and making its way into the weld. I had to grind it out and do it again. Second time was better. I then contoured the weld with the burr.
I should also mention that the fumes from this type of welding are toxic and not for humans to breath. More so, when there are traces of braze in the weld area.
Use some type of approved face mask to stop the fumes getting in you. They are linking this type of toxisity to Alziemers and other disorders.
I feel confident that this is the reason my immune system was weakened and allowed a mosquito bite to give me Ross River virus.
I have had Ross river for 6 years and it is very similar to West Nile (for those of you in the States) or Chronic Fatigue syndrome.
For the sake of a couple of minutes fitting a mask or the small inconvenience of driving to the hardware store to get one....figure it out...20 minutes or 6 years.

Now that the welding is complete, I will have a fosick around the net for this stress relieving issue that toprock has suggested.

[exeric]

You're doing a beautiful job Steve. At first I was thinking you were going to disassemble the fork to insert a reinforcement. That would have been quite a trick. Obviously you are a very talented welder and have taken all the right steps to make a good repair. I think it was Chris Haynes who posted a picture of a fork crown that had been cut and sectioned to show the insides.

[Rubone]

This is the stem picture Steve, not sure if it tells you anything.
Robbie

[Steve Little]

Thanks Robbie.
Someone spent a long time with the hacksaw on that project.

In your picture I can see that the inner channels are clear, and look to have their backs brazed to the stem.

Like the other components of the stem crown, these channels have been forged specifically for this job.
Stem crown chanel 001.JPG

After fossicking around on the net I found the following in the Lincoln Questions and Answers section. As follows:
Q. Do I need to heat treat (stress relieve) 4130 after welding?

A. Thin wall tubing normally does not require stress relief. For parts thicker than .120", stress-relieving is recommended and 1,100ºF is the optimum temperature for tubing applications. An Oxy/Acetylene torch with neutral flame can be used. It should be oscillated to avoid hot spots.

Thanks for the prompt Toprock.
I will have to be careful during the heat treatment process, as braze also melts at 1.100F. The heat will be put into an area that is very close to where the leg is brazed into the stem crown.

On a side note , I took a picture from the top of the handlebar mount area of the leg. The pin can be seen in the spring crown.
I have been asked quite a few times over the years if Harley pinned the forgings to the tubes before brazing. I know that pinning was done on W series frames but I have never found a pin in any of the big twin frames (1937 and up) that I have worked on.

[Steve Little]

Thanks for the encouragement Eric.

Stress relieving process is done.
It’s been so long since I last used this thermometer that it took me 15 minutes to find it. I am suprised the battery still had charge.
I brought the weld area up around 1100F. The whole area was dull red colour.
I put the torch down for a second and tried to take a picture of redness of the steel when it was up on temperature. But out of habit, I had turned the camera off. By the time I had turned it back on, and changed the setting to low quality for the forum limit, some of the redness was already dissipating.

My process as follows: I got it back to around 1100 and held it there for a few minutes. Then backed the heating tip away from the job for a bit, and then allowed it to air cool.
How’d I do Toprock??
.
The actual time to repair this rear leg has been a bit over 6 hours.
My shop rate is $90 an hour.
I sporadically visit eBay and haven’t bought any bike parts for about 12 months.
I haven’t been to Davenport for 2 years, so I feel out of touch on prices.
Maybe HD’s policy on these legs is still relevant.
What’s the consensus out there from you readers?

[Peter Cooke]

For me $540 is money well spent when you consider 2 things;
1. The endless possibilites of what might happen should a cracked fork leg let go at 60mph and
2. Early springer front ends sell for way more than that on Ebay and there's no garuntee that they are not cracked and require further work. At least your customer now knows what he's got and can ride with peace of mind.
HD's policy was fine 70 years ago when there was plenty of spares available. It's not really relevant now.
If guys like you don't do what you do then less and less old bikes get back on the road.

Keep up the good work!

[harleytoprock]

Steve, Bravo! Excellent Job! I would feel extremely confident riding on that fork. Thanks for sharing. HTR