What aluminum alloy is used to weld the side case of my X75 Hurricane?

Hurricanex75rid

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Regardless of it’s physical value, I rebuilt my Hurricane to enjoy the handling, the sound of its triple, and the thrill of shifting at 8,000 rpm’s. I rebuilt, not restored it, to ride not hide!
The left side oil feed from the crank journal plugged and the rod let go. Being a late 60’s BSA A7 (Rocket 3) motor, the alloy used for the casting might have been used in the Triumph and Norton since they were under the same umbrella of ownership.
I’m in need of information for what tig rod alloy should be used to weld the crack.
Now you can stop reading and not get bored with my story of how I came about my Hurricane story or continue and find out how it came about! Here goes:
I grew up in the outskirts of Toledo Ohio farm country. I had a mini bike that I rode it the woods, on the rode, and frozen creeks, and ponds having added screws through the tires. At 15, I started my machine training and had availability to bore and shave the head plus port and polish being that I was working as a plastic mold maker apprentice and 2 years of Vocational Machinist training. I finally got my first car, a 57’ Ford. As my wage increased, at 17, I purchased a Ford Mach1 Mustang with a 390. It was bad ass from the factory but with 2 friends working for a Ford dealer ship, they re-built it our way after blowing up 2 engines, 2 trannys, and 1 rear end. ALL UNDER FORDS WARRANTY!
I was driving when I say my friend on the first Hurricane sold in Toledo. We both stopped and was BS’ing. The bike was something that was so different that I said to Kenny I would love to ride it. He says, let me drive your Stang’ and you can ride my Hurricane. Agreeing on a time and place to meet later, off we went.
Throwing my leg over and sitting on it was a WOW moment! The feel, the way the bars angled, I just sat and admired it. Then when I heard the sound!! That was the first time I knew I wanted a bike like this. No twin BSA, Triumph, or Harley’s for me. I never forgot that first moment.
I moved to Jacksonville Florida and never saw that bike again until the early 80’s. I visited a friend (Jeff) in Boaz Alabama who was the Hurricane’s owners good friend and found it on shelves in pieces, literally. He had bought it, beat the hell out of it, and needed to rebuild it. We agreed if he got rid of it, I got first chance to buy it. Fast forward to 1999.
I went back to Toledo for my 30th school reunion. I was at his brother Bill’s farm when within an hour, Jeff pulls in on my second favorite bike, a bad ass Vmax. Not saying hello, I said, where’s my bike? Jeff’s says, I haven’t heard from you in years, well you ain’t going to believe this, but just 2 weeks ago, I gave it to brother Jake. Having partied our ass’s off with Bill and Jake, I devised a plan of attack. I knew he needed a hip replacement and couldn’t ride until it was replaced. I bought a 12 pack and headed to Jakes house. After several beers and his eyes were getting glassy, I asked about his beautifully restored Harley. I can’t even ride it anymore! There was my intro, well if you can’t ride, what the hell you going to do with the Hurricane? He says, Jeff told me 2 weeks ago, you were supposed to get the bike but we had no way to contact you so he gave it to me for a some mony he needed. You want it don’t you? Hell yes, what’s it going to cost me. You really want it? I said, stop f@&king around, yes! He says okay, you can have it. Ok, how much? Just take it, it’s in my way. Well, I it was in pieces, with parts stripped and gone and in worse condition than when I last seen. I didn’t care, it was now mine after having rode it 26 years prior. I strapped the frame to the ac unit of my motor home, the body under the bed, and stashed parts everywhere I could. It took ten or more years to find as many original parts to start rebuilding. The motor inner 2 casings, crank, rod, and pistons were still intact and I decided to not tear it down any further. That is possibly where the problem from the oil flow stopped to the rod. I got 4,000 miles on it before it gave up.
After this rebuild, I’m going to treat it like it needs to be treated out of respect of surviving the 3 people who rode the piss out of it.
It is going back to stock bore. The original carbs, I bored the bodies and sleeved the slides. Every gear has been drilled and machined to run true to the shaft axis. Internal clutch casting have been machined to run true. The crank, rods, piston assemblies have been race quality balanced. I decked the cylinders to within .001 after finding it out .007. I fly cut the head to true it up flat. It’s ported. I also drilled the 4th oil circuit in the crank for tru oil flow.
I’ll play hard with my 1995 Triumph Sprint setup for track racing but street legal.
 
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grandpaul

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Great post, sorry I can't help you with the alloy specs to effect the repair.
 

Hurricanex75rid

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I want to share what I’m machining to hold the left side case to my X75 Hurricane. If your going to ride one as hard as I do, you better be able to repair it! Right, or hope who you trust to repair it does it right!
This fixture should help to keep the bores straight and perpendicular to the casings face. If not I will have to bore and sleeve the case. It not a big problem, it’s just time intensive.
Here’s what I’m machining:

This side of the plate is for welding the outside of the case. This is the case with matching numbers to the frame. It has to be used.
The hole and pocket in the middle is for the aluminum locating pin machined to size for locating the crank bearing hole diameter and will be used to prevent movement from welding. It will be bolted from the other side. It will be machined 2.000, to slip fit into the pocket which is 2.0015 in diameter x .300 deep. It will slip fit into the casting and will be 1/32” under the casting face. A top cap will be bolted in the center to keep it against a shoulder on the opposite side of the face machined to the proper height to prevent movement.
The other two holes will have dowel pins machined and pressed in, to fit in the cam bearing holes. The two small dowels locate the casting centerline of the crank bearing hole and locate in the side of the motor casings. The small holes are drilled and tapped though. This is for alignment of the same holes when the plate is turned over and the casing is mounted for welding the inside.
The groove was cut to allow the casing face to set flat because there is a protruding lip on the inner face inside of the bolt holes.
Before welding it gets preheated. After welding and before removing from the plate, the assembly will go into the over for a period of time, soak, and then cooled down. Hopefully it will come off the pins!
If not, I’ll have to re-machine the bores and sleeve them. This case will go back on one way or another!! I’ll use the plate for the re-machining the case if it’s needed.

44057


The rods represent the bolts screwed into the holes. There are 5 spot faces that are close to the same height. I’m going to machine them to the same height. The 2 on the left side are different than the 5, so I’ll machine them the same height. There’s one in the middle of the 3 on the right that will be machined the same as the 2 on the left. The top middle is different. I have to leave it alone because it is the face for the oil pump. Each one will be measured from the crank bearing face (the hole in the center) down to the bolt face. I will make spacers to fit so when bolted through, the flanged face of the whole casing will be held flat.
44059


This is the plate flipped over. I will machine a center plug shorter than the one used for the other side. The casing face will mount flush and be bolted using the same cap used on the other side. Spacers will be machined to fit between the plate surface and each bolt faced I machined, then bolted.
44055

The long pins just represent the bolting pattern.
44054

The same threaded holes had to be through threaded for bolt location. The space between the plate and machine bolt face is where the spacers will be.
44056

The 2 cam bearing locating pins on the left and center crank bearing pin will be slip fit. Pins in the picture are for representation only.
44058


The top aluminum piece pictured, is what I’m using to locate the case when it’s flipped over to the other side. I set it there to represent the plate that will be drilled and used to hold the casing down.
44060

I hope we get lucky!
 

grandpaul

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VERY interesting! Good work, keep it up.
 
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Hurricanex75rid

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Added pictures of the progress.

This gets bolted from the other side.
44075


44078

This plug is for location when welding the inside
44073

The inside plug machined to match the inside flange of the crank bearing diameter when welding the outside. The same diameter slips into the pocket of the steel plate.
44074

The hold down cap.
44076

I added the holes and threaded them because if they are hard to remove after welding, I can run a 3/8’s bolt in the drive them out. I’m hoping I reverse engineered the dimensions so when the pins are pressed in the steel plate, they line up!!!
I hit the 3/8” dowels perfect so maybe I got lucky.
44077
 
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Rocky

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Great stuff TUP TUP
 

Hurricanex75rid

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Added pictures of the progress.

This gets bolted from the other side.
View attachment 44075


View attachment 44078

This plug is for location when welding the inside
View attachment 44073

The inside plug machined to match the inside flange of the crank bearing diameter when welding the outside. The same diameter slips into the pocket of the steel plate.
View attachment 44074

The hold down cap.
View attachment 44076

I added the holes and threaded them because if they are hard to remove after welding, I can run a 3/8’s bolt in the drive them out. I’m hoping I reverse engineered the dimensions so when the pins are pressed in the steel plate, they line up!!!
I hit the 3/8” dowels perfect so maybe I got lucky.
View attachment 44077
I could have hid my mistake, but that isn’t the way I am. I make mistakes, but I figure ways to correct them and save from remaking and spending time and money to redo my work.
Also, I’m showing what a Machinist has to do with the setup, find the dimensions of the case bores, and make a device to try to reduce warpage.
With this information I’ve provided, it should help anyone, with a triple or a twin how to setup and repair a case. Most people with an original Hurricane wouldn’t ride one hard and throw a rod! As I said previously, that’s not the way I am. I will ride it sensible this time?? MAYBE!
Here’s my repair of my mistake:
When I was plotting the dimensions I missed the centerline of the crank bearing centerline. Instead of making a new center plug, I spot welded the hole.
44131



I indicated the left cam hole, set zero, and moved to the right hole after resetting my digital read out to zero.
44133



44136


I found center and had the centerline dimension of the bores. I split it in half and reset to zero. Note that I’m using a half thousandth indicator. It’s showing 1-2 ten thousandth off zero. That’s a human hair split fifteen times, so I’m close enough!
44130



44132



44134


I moved to the center.
44135
 

Hurricanex75rid

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I reset to zero.
44138


I then moved to the crank bearing bore and found center. This establishes the correct centerlines on my A75 motor. I’m assuming it would be the same on Triumph triples also. When I tried to find the centerline prior, I used my other mill without a digital readout. I had a brain fart and missed the dimensions. I’ve racked my brain and have no idea what I did wrong.
44137



44140


I switched over to the other mill and used gage blocks setup to the new centerline dimension. I picked up the centerline of the cam centers again. Using the rotary table I dialed in the centerlines parallel. I also indicated the back edge just to verify parallelism.
I placed the gage blocks against the table front and set an indicator against them to zero. I removed them and moved the table to the same zero to place the centerline of the crank diameter in the right location.
44139



44141



44148



44142


I went back to the centerline of the cam bores to verify since I made the wrong move before, just to verify.
44144



44143



44145



44147


I moved back to the corrected crank centerline and rebored the locating hole so when I turn the plate over, I have the correct centerline locacation.
44146
 

Hurricanex75rid

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44149


44153


Rechecked and nothing had moved.
44151


Using the rotary, I recut the ID to the dimension of the aluminum center plug.
44150


I only spot welded 5 locations in each half of the original hole to eliminate excess heat.
44152


I removed the plate and picked up centerline of the rotary table.
44154


44155


I indicated the machined surface of the plate. This surface was machined parallel to the cam bores for ease of setup.
44156


44157


So far so good.
I machine all the bolt spot faces to make the spacers described previously.
I bolted the case in place and put it in my oven at 350 degrees for 2 hours and let it cool down.
Next is measure from the face of the crank bore to the bolt counterbore faces to make the spacers for bolting when the inside is welded.
I won’t “bore” you anymore with machining.
Now to setup the tig with the proper gas and rods. Call my friend who’s doing the welding and see if all of the effort pays off.
If someone can use this or improve on it, feel free to share it.
 

Hurricanex75rid

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Here’s how I measured for spacer dimensions.

44174

The 1.240 is for the hole at the crack
44175

44176


Now make spacers, bolt it down, preheat, weld, post heat and see how it turns out!
 
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ChrisAnglophile

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Here’s how I measured for spacer dimensions.

View attachment 44174

The 1.240 is for the hole at the crack
View attachment 44175

View attachment 44176


Now make spacers, bolt it down, preheat, weld, post heat and see how it turns out!
The first thing I need to say , is that I qualified as a Electrical Engineer , not a welder.
But I have done all the Welding courses at Tech (TAFE) and passed them all , including TIG.

I have welded , lots of alloy , including some cases.
Norton's and Triumphs at that time were separate companies , not at all connected.
Triumph was part of the mighty BSA company.
Triumph cases on the twins is better , stronger alloy than on the Norton's!
But having said that , i don't know much about the triples .
( no help at all )
However , Aluminium castings do have to have Silicon , to help it flow in the casting.
10 to 15% is the Norm.
I have always found , 10% or 15 % Silicon Aluminium welding rods to do the Job just fine.
The trick, is to preheat the casting with a oxy set to about 350 ' C and do a Root Weld first..
Unfortunately , the otherwise side will Oxides and will need cleaning again before welding.
Shrinkage if preheated won't be so bad , but it will have to include the backing steel plate.
Its one of the reasons I would not have gone to so much trouble than you have.
With you holding it so dimensional solid , the weld on cooling has no where to go and might just crack as it cool's.

A much more important issue is getting all the bolt holes between the frame and the Engine true and a perfect fit.
Shuffling of cases and out of line Engine bolts is a serious problem on all Brit bikes.
Its the difference between a good handling race bike and a bag of bits.
It will be interesting to see the results.

Chris
 
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ChrisAnglophile

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You two are WAY above my meager skill levels!! Respect!!
I respect anyone who gives it.
I also have great respect for anyone who served in any of the 3 services for their country.
Especially that hell called Vietnam or Iraq or Afghanistan or Northern Ireland , after the Wars to End all Wars.
 

CarlS

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I respect anyone who gives it.
I also have great respect for anyone who served in any of the 3 services for their country.
Especially that hell called Vietnam or Iraq or Afghanistan or Northern Ireland , after the Wars to End all Wars.
Thank you, sir. I also served with some mighty fine Diggers! Great guys and darn good soldiers.
 

Hurricanex75rid

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Here’s how I measured for spacer dimensions.

View attachment 44174

The 1.240 is for the hole at the crack
View attachment 44175

View attachment 44176


Now make spacers, bolt it down, preheat, weld, post heat and see how it turns out!

Here are my reading off the flange face. As I make the spacers, I sizing them to bring the minus numbers close to zero. The plus readings, I’m leaving that amount short to draw it to zero. Chris pointed out the bolts lining up. I used a transfer punch to pickup the holes. The bolts slip right in. With the case turned over the holes are misaligned on three of the tapped holes. Maybe a 1/64. I’ll put a steeper lead angle to get them to start. Being the spotface is resting on the 3/4” spacer, it will be held flat. We may be welding tomorrow. We agreed to weld the outside after preheat of 350-400 in my shop oven. He will stitch weld the crack. It will go back in the oven at the same temp and I’ll cover the oven to let it cool slow overnight. Do the same next day on the inside.
The gentleman doing the welding has welded for 50 years. Power plant, Marine, Toolmaking, AWS, Low Pressure Pipe, and could certify ASME for high pressure boiler tube repair, plus he’s a former Pro-stock Motorcycle builder/rider. He’s welded on casings for himself and my Hurricane. He confident as I that it’s the only way to try to stop warpage. If it cracks, we’ll keep welding until we get “r” done.
44178
Thank you, sir. I also served with some mighty fine Diggers! Great guys and darn good soldiers.
 

ChrisAnglophile

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I haven't got the time right this minute.
But Oil from use is in the casting , its a pain to get the stuff out.
Some will come out with a soak in petrol overnight.
But mainly , its necessary to heat with the TIG and watch it pour out the casting.
Takes about 5 times or more of Heating with the TIG and cooling it and Scrubbing Acetone and Wire Brush to get anywhere.
In the mean time , gives you time to make a metal backing plate , to fit the other side of weld.
With a ridge down centre to let Argon Flow. That way , less clean up , on other side, before welding.
Once welded , the trick is to heat with a torch , other areas to get it to slowly cool, an shrink in none welded point last.
Otherwise its horrible to hear it cracking in front of your eyes, straight down the middle of the weld.
And if you think that's frustrating , I won't ever weld Magnesium Again.
Chris
 
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