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Fork Material

9K views 30 replies 11 participants last post by  bluezuke860 
#1 ·
Hey, what are the forks made out of? Is it steel or aluminum? I just read that the fork extensions are made out of aluminum, so I'm wondering if the forks are the same? If not, don't you think that could be a problem matching two dissimilar metals together?
 
#8 ·
From a corrosion standpoint you won't have any issues being that neither metal is prone to corrosion. as far as expanding and contracting at different rates I'm sure they will,, but I'm not sure how far off they'd be. Since the cap is solid and the forks are not I would thinke (and this is just speculation) that the 2 peices would expand/contract at different rates anyway even if they where the same metal.
 
#9 ·
St. John is right...The two pieces would expand and contract at different rates even if they were both kind of steel. It is probably your threads and the steel, being harder then the aluminum, bending the threads. Work and engineer with different kinds of metel everyday. Just my thoughts...
 
#10 · (Edited)
Parrot

Not good if the fork extensions are aluminum. The guy selling those things is crazy - if he's putting threads on aluminum parts. They are not going to have enough strength over the long term. The Raider is a big, heavy chopper with a lot of rake angle. That puts a lot of bending stress on the forks.

I am actively tracking down a source for replacement steel forks for the Raider - so that longer one-piece forks can be made. It's not as easy as it sounds. The Raider fork tubes have an OD of 46 mm (i.e. it's a metric size, and not a common one). There is no spare stock of steel fork tubes out there that matches this OD. It's possible to get a source of mild steel, then have someone make fork tubes from scratch - but the machining and grinding is not cheap. I guess that Yamaha probably has a supplier make and grind their fork tubes to their own specs - as required. I'm still working on it.

cheers,
dT
 
#11 · (Edited)
Alright ... let me pass on this important tidbit of information.

I just got off the phone with the major American manufacturer of steel for forks in metric motorcyles. I pointed out to them that some guys were selling fork extensions, instead of encouraging people to use longer one-piece fork tubes in the bikes. Their response was this ... "Yeah these people are absolutely crazy and we've been saying that for 40 years. For any big bike, the stress and vibration on the front forks is high and these fork extensions are NOT safe!". So consider that as input - if you are running these fork extensions on the Raider (or thinking about them).

But the headache goes on ... because we just CANNOT get replacement steel tubing with the right dimensions for the Yamaha Raider. The Raider tubing has 46 mm OD steel for the fork tubes, and this is not commonly produced in US steel mills. Nobody's got it in stock, and nobody's planning on getting it in stock any time soon. So it boils down to re-engineering a complete front suspension set-up, if you really want to change the fork length properly. Doesn't mean I've necessarily given up. It does mean we're looking at a reality pill - if the goal is to do this job properly.

By the way ... although we like to give HD a hard time here, apparently they did a really good job with the strength of the front suspension on their new HD wide glide. That bike has fork tubes with walls that are very thick - some of the strongest fork tube on the market. Just an interesting side comment.

dT
 
#15 · (Edited)
This thread is becoming way too painful. So, this is how it's done. 46mm=1.81". Start out with 2" O.D., chrome moly bar stock. Have it cut slightly longer than required (it will need to be cut to it's exact length on a lathe). Then, have it gun drilled to the proper I.D. and threaded. Once that's done, have the O.D. turned to within + 0.005 of its finished diameter. After which, you'll need to have it concentrically ground to 0.0002 undersize. Then, the tubes will have to be sent out and plated with 0.0003 of hard chrome. The last step will require the tubes to be re-ground again, to their final O.D. This will give you fork tubes that are 46mm O.D. (1.81), with 0.0002 of applied hard chrome. If you get enough orders together, you'd probably get a pretty decent package price.
 
#14 ·
OK here's where I'm up to.
Like I said - I have not given up at all.

We can re-build the Raider into practically any bike we want ... it just takes time, perseverance, and a really bad credit score (!).

1. We could look for an overseas supplier for fork tube material. I'm thinkin' that there's probably a place in Japan that has this metric fork steel. It would just take time to locate them. Plus they'd have to ship us the final order.

2. Yeah - we could also get a hold of some 4130 steel alloy tube from the USA with the correct inner diameter, and have somebody machine and grind the outer diameter. That's always feasible - it's just a question of cost. Probably pricey.

3. But the best alternative is a suggestion that Parrot65 just gave me in a private message. Why not keep the fork tubes the way they are ... and re-design the TripleTee's on the Raider? Actually, I think it's only the top TripleTee that needs to be re-done, and then it would grip the fork tubes at a lower level. I really like this approach because a TripleTee is a strong component - I can definitely design one that's super-strong (even stronger than what we've got now). And it's not to hard to replace on the bike. And it's also not hard to find guys who can machine some of these items for us - to make a final product.

I'm gonna' start working on Option #3 above. Stay in touch if you are interested.

dT
 
#16 ·
What's the I.D. of the fork tubes? You can find 1.875 O.D. tubing fairly easily, which would give you less work to get it down to size. Most shops charge by how much work they have to do so if you can start closer to size it would save you some $$$.
 
#18 ·
The difference between 1.810 (46mm) and 1.875 (1 7/8") is 0.065 (or 0.0325 on a side). If there is any runout or dings in the tubing, there might not be enough material left to clean it up. When finished, these tubes have to be absolutely straight, concentric, and un-blemished. Tubing suppliers will guarantee uniformity of wall thickness, but that's about it.
 
#17 ·
Paladin

OK ... fair comment. I'll try to price both options - machining and grinding of new forks, or re-design and machining of top Tripletee.

1. Re-doing the forks would give the bike more of the classic "chopper look" ... which is probably what most people are looking for.

2. Re-doing the top Tripletee would raise the front end of the bike, and might also increase the forward offset of the forks.

Either way - costs are probably lowered if several people order.

dT
 
#20 · (Edited)
Yeah, I think we're getting on to something here!! Whatever supplier/manufacturer guy takes this on could potentially make some money, because there are tons of Raider owners that would love to do a SAFE mod. I'm going to see if I can find this tubing too to assist dT.

The one thing to keep in mind is that whatever you find would need thicker wall thickness so the milling down of it doesn't make it too thin.

By the way, the exact measurement is 46.00mm = 1.811025"
 
#21 · (Edited)
We'll check prices.
I think in the end it's going to boil down to the total cost of the mod.
If we can keep the cost down to several hundred $$, then probably we'll have some guys who want to do this mod.

If it gets too expensive, guys are gonna' figure - why not just re-do the front end of the bike? You could put on a front end from HD, or a Springer suspension, or some inverted telescopic forks. Those kinds of jobs will cost around $2000-$3000 depending on how fancy you want to go. But possibly some people on this forum have been thinking about those options anyway.

Right now I need the ID of the fork tubes. I can go measure that, but not for about 14 days. I've got two big Spring rides happening on my Raider in the next 2 weeks. So I'm not doing any projects until I complete all those miles. After that - I'll be heavily involved in mods over the summer.

dT
 
#23 ·
I can't speak for everyone but, the main reason I went with the extensions besides the look was because I have huge forward controls installed and they drag pretty easy especially since the back is lowered. Bringing the front up has been a huge help.
 
#24 ·
The shop I work in works with tubing of all sizes and the raw stock comes in straight and round (most of the times!) and .032 per side would be plenty of stock to work with. We've cleaned up tubing with as little as .010 stock per side to work with. As long as it's round and straight it'll work! The times that the stock has come in bent, we've straightened it and finished it no problem. Any decent shop should have the capabilities to do so.
 
#26 · (Edited)
Msoos: I'll be in touch with a private message. Watch for it!

TysonTy and Matt:

I have the same interest as Matt. I would like the front end of my bike to be a little higher in front - have a bit more ground clearance. There are several ways to accomplish this, but the 2 best ways are either to re-do the front forks or to re-design the TripleTree's (actually it's probably just the top TripleTree that needs to be re-designed). After thinking about it, I realized that the option that gives the bike the best aesthetic appearance is to do what Paladdin has suggested - produce new steel forks starting from tubing with a different starting OD. I think most of the guys here who want this mod will be happiest if their bike looks like a chopper - which means having an extended fork length. Based on what I've seen done, an increase in length of about 4 inches looks good on the Raider.

Changing the TripleTree would also work for raising the height of the front end of the bike - but it would make the top of the front suspension look a bit like the top of a Springer ( ... but without the cool tubing and springs that really go with a Springer suspension). It would also add weight.

So I'll explore both approaches, but I am leaning towards what Paladdin has suggested.

dT
 
#30 ·
Changing the TripleTree would also work for raising the height of the front end of the bike...
This would probably be the easiest and cheapest way to go. BUT you'll probably lose the "chopper look" alot of these guys want because instead of the forks being extended further forward they'd have to be brought in towards the bike in order to raise the front end.

The Raider has a stock rake of 38 degrees. When you use lowering dog bones it changes to about 39 degrees. So I'm guessing off the top of my head that to raise the front of the bike another inch or so you'd probably have to have a rake of about 35-36 degrees (remember I'm just guessing here, it needs to be figured out mathematically). You'd just have to mill a new set of trees instead of messing with tubing.

One plus would be that the bike should handle better in the curves, especially if you had a good fork brace just above the fender.
 
#28 · (Edited)
Paladin, if my name was on the building, I'd be on it like white on rice! I just work there but I'll run it by the owner and see if he'd be interested. I'll let you know! Does anyone know the dimensions other than the 46mm outer diameter? What threads are on it and what lengths are you looking for?
 
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