cut & weld GSXR steering stem

C

chickenStripCharlie

Coast to Coast
thinking of having this done, but before i go looking for a fabricator, has anyone here done this?
What type of aluminum is the stem made of, does anyone know?
It looks like aluminum, but it feels like a tougher alloy rather than plain aluminum.

The stem is hollow, so it should be possible to sleeve and weld, as long as the material composition allows for that. Be curious to hear exactly what it is made of before i reach out to a welder.

The stem in question is from a 1999 GSXR 750

Thanks!
 
I'm a welder by trade. If that was brought to me and i knew what it was for, i wouldn't touch that job with a 10ft pole for the liability, or even morality of it. To many ways things could go wrong if it cracks.

Pressing stems into different triple is one thing, cutting them to shorten or lengthen then welding them back together is another.

just my 2 cents.
 
Hurco550 said:
I'm a welder by trade. If that was brought to me and i knew what it was for, i wouldn't touch that job with a 10ft pole for the liability, or even morality of it. To many ways things could go wrong if it cracks.

Pressing stems into different triple is one thing, cutting them to shorten or lengthen then welding them back together is another.

just my 2 cents.
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Can you elaborate? Are you saying that for this particular stem material, or just the act of welding on any stem in general? If so, why, when the stem is hollow and an inside sleeve could be machined with a very tight tolerance fit. I'm NOT a welder, but i'm trying to understand why this set up would not work if done by a competent welder.

I have seen it done before, granted with steel stems, not these aluminum ones. So i'm just doing my research for now.

Thanks!
 
You mean you want to section it? Cut a piece out of the middle?

I had a steering stem shortened. Left the top alone, cut an inch off the bottom and welded it into the lower tree (steel on steel - the steering stem is highly unlikely to be anything but hardened steel).

The lower bearing needed a fresh seating surface, so they welded on some material and turned it down to the ID of the lower tapered steering bearing.

The better option is to get the stem you need to match your frame, and have it mated to the triple tree you want to use for your forks.

What are you putting the GSXR front end on? It's very common and most times you just need different bearings from All Balls. I think they even have a tool to tell you what you need.
 
chickenStripCharlie said:
Can you elaborate? Are you saying that for this particular stem material, or just the act of welding on any stem in general? If so, why, when the stem is hollow and an inside sleeve could be machined with a very tight tolerance fit. I'm NOT a welder, but i'm trying to understand why this set up would not work if done by a competent welder.

I have seen it done before, granted with steel stems, not these aluminum ones. So i'm just doing my research for now.

Thanks!
Click to expand...
Yes, mostly due to the fact that it is aluminum, of an unknown grade. Very likely a hard grade (6061 or higher) which can be welded, but can also be prone to cracking, either in the weld cross section, or at the edge of the heat affected zone. I would give it a whirl if it were steel, but I wouldn't attempt it with the aluminum. Not on my own machine nor on a customers. There will be guys out there that would weld it for you I'm sure. And again, just my advice, which is not the be all end all. If you are going to find a skilled craftsman for this project, I would recommend it being a machinist that can make you a new stem with your needed dimensions to press into the triple instead of welding it. Also, like Tim said, check out allballsracing to see if they have the bearing swap you need anyways.
 
Tim said:
You mean you want to section it? Cut a piece out of the middle?

I had a steering stem shortened. Left the top alone, cut an inch off the bottom and welded it into the lower tree (steel on steel - the steering stem is highly unlikely to be anything but hardened steel).

The lower bearing needed a fresh seating surface, so they welded on some material and turned it down to the ID of the lower tapered steering bearing.

The better option is to get the stem you need to match your frame, and have it mated to the triple tree you want to use for your forks.

What are you putting the GSXR front end on? It's very common and most times you just need different bearings from All Balls. I think they even have a tool to tell you what you need.
Click to expand...


It's a 1999 GSXR 750 fork (aluminum stem & clamps) going onto a 1983 CB 750 nighthawk (steel stem & clamps).
Using the original stem in the GSXR forks would not work as it is of a wrong diameter to be pressed into the GSXR lower triple, so the original would have to be cut out (as it is welded) and the entire bottom section redone, including a "lip" to prepare it for a press fit ... not easy either.

I have the bearings required already, but the stem is too short for the CB nighthawk The upper bearing sits on the threads as the bearing surface is too far down. Hence the 15mm extension that is required.
 
Hurco550 said:
Yes, mostly due to the fact that it is aluminum, of an unknown grade. Very likely a hard grade (6061 or higher) which can be welded, but can also be prone to cracking, either in the weld cross section, or at the edge of the heat affected zone. I would give it a whirl if it were steel, but I wouldn't attempt it with the aluminum. Not on my own machine nor on a customers. There will be guys out there that would weld it for you I'm sure. And again, just my advice, which is not the be all end all. If you are going to find a skilled craftsman for this project, I would recommend it being a machinist that can make you a new stem with your needed dimensions to press into the triple instead of welding it. Also, like Tim said, check out allballsracing to see if they have the bearing swap you need anyways.
Click to expand...

Thanks for the advice! I have reached out to a local machinist for a quote already.

my research shows they are likely 7075 Al, or even 7068 .... i have no way to verify that, however.
 
chickenStripCharlie said:
The original would have to be cut out (as it is welded) and the entire bottom section redone, including a "lip" to prepare it for a press fit ... not easy either.
Click to expand...

That's still the way i would go about it vs cutting and welding the aluminum stem. If easier doesn't correlate to safer or better, I choose safer or better.
 
Hurco550 said:
That's still the way i would go about it vs cutting and welding the aluminum stem. If easier doesn't correlate to safer or better, I choose safer or better.
Click to expand...

It also does not allow me to use the GSXR top triple, so that would be a a no-go. i just realized this. would need the top redone with a "shoulder" machined for the top triple to sit on.
 
chickenStripCharlie said:
Thanks for the advice! I have reached out to a local machinist for a quote already.

my research shows they are likely 7075 Al, or even 7068 .... i have no way to verify that, however.
Click to expand...

Those grades would both be believable. unfortunately, 7075 is un- weldable. If you want to go to sleep, google "7075 phase separation"

basically the elements that are alloyed to make that grade of aluminum un- mix or separate when they are made molten.
 
I cut, machined and pressed my TL1000r stem together to fit a BMW R100/7 frame. Ran it with the VH front end, then the TL front end. Over 3k miles and I'm still walking. Oh well.
 
Hurco550 said:
Those grades would both be believable. unfortunately, 7075 is un- weldable. If you want to go to sleep, google "7075 phase separation"

basically the elements that are alloyed to make that grade of aluminum un- mix or separate when they are made molten.
Click to expand...

so keep it cold and use JB Weld then?

JK .... thank you for the advice. i really appreciate it. Cognito Moto makes the exact stem i need, just trying todo it a little bit cheaper as the exchange rate is terrible so with shipping to Canada i'd probably be out $280 or so just for the stem.
 
No welding, just pressed together. The top piece is press halfway down the bottom piece. The OG BMW stem is pressed into the bottom tree. The nut holds it to the frame and bearing, the top section is just for the top triple, which doesn't need to be nearly as stout as the bottom.

6fae4354137f5e9b6d552ebc688ff887.jpg
 
irk miller said:
No welding, just pressed together. The top piece is press halfway down the bottom piece. The OG BMW stem is pressed into the bottom tree. The nut holds it to the frame and bearing, the top section is just for the top triple, which doesn't need to be nearly as stout as the bottom.

6fae4354137f5e9b6d552ebc688ff887.jpg
Click to expand...

I assume you mean the shiny piece is pressed into the dull bottom piece? (looks like there's a seam below the bottom threads, but I assume that's just where the bearing has sat and left a line)
I'd throw a roll pin in it just for the security adnd call it a day.
 
SONICJK said:
I assume you mean the shiny piece is pressed into the dull bottom piece? (looks like there's a seam below the bottom threads, but I assume that's just where the bearing has sat and left a line)
I'd throw a roll pin in it just for the security adnd call it a day.
Click to expand...
The shiny piece is TL1000r. The dull piece is BMW. Have you seen an airhead top triple? That shiny piece is pressed 3 inches into the bottom piece. The top bearing is held by the threads on the BMW stem. Please show me the math that suggests this needs a roll pin. Like I posted earlier, this has over 3k miles, and nothing has moved even a thousandths of a mm. The top triple is being held at the top screw AND the forks.
 
Yes, for your application that works, because the top part holding the clamp isn't seeing as much force.
For me, the stem is too short in the middle, below the top bearing aka critical section. It's also too small to have the GSXR section pressed into it, if i was to use the original stem
 
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As said already, if you need something longer than the GSXR stem, get a new one machined. I have had a GSXR stem machined and pressed into other bottom triple clamps.

As Irk alluded to, the major stress on a stem is with the bearing nut. The forces between the stem and top clamp are far lower. That's why it's not an issue for his application
 
cxman said:
get ahold of cognitomoto they make that stem

its not worth the risk
Click to expand...

Yeah, they do, for about $200 and an additional $50 to ship to Canada.
The entire front fork cost me less than that

So cognito is my last resort right now simply due to price. will see what local machinists want to redo the piece.
One already turned me down on account of it having metric threads ?!? ..... wtf kind of machine shop is concerned whether threads are metric or imperial?
 
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