How important are straight axles on your front truck?

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Brian Peck
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How important are straight axles on your front truck?

Post by Brian Peck » Fri Apr 14, 2006 5:19 am

I've been wondering about this for a while. Obviously, straight axles are a biiiiig plus on the rear of your board. I upgraded from a stock Tracker RT-S, to a modified RT-S with a straight 8mm axle and immediatly felt the improvement. From there I upgraded again to an Airflow OS and felt the difference in having the axle in line with the kingpin. But that's for back trucks... how do these principles compare with front trucks?

I've ridden stock Tracker RT-X's, modified RT-X's (straight 8mm axles again), and Splitfires in front. I don't like the Splitfires at all; I feel like the geometry really slows down my pump. On the other hand, I've got my RT-X tweaked perfectly and wouldn't trade it for anything. However, I haven't really got to compare the stock and modified RT-X's head to head. Do you think I will notice a difference? Is it worth the upgrade to have them modified? It's very easy to get a truck with a bent axle to slide out in the back, but I've never felt a loss of traction from the front wheels. An 8mm axle will help bearing alignment and in turn will help with a bit of speed, but is a straight axle in the front of your board really important?

Opinions, please.

Tod Oles
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Post by Tod Oles » Fri Apr 14, 2006 6:33 am

Brian,

Obviously the wider the hanger is, any misalignment(s) will be magnified...

I rode a stock Seismic in front for awhile, which had pretty nice axles and hanger faces...
but I noticed a slight difference in both speed and turning precision when I started using Biltin bearings.

For the next big upgrade I mounted up a Roeracing S-camber w/ a Radikal
front and a Splitfire rear and sat this setup on my kitchen countertop... it started to roll away
after just sitting there for 5-10 seconds...

My trusty carpenters level says the countertop is dead flat....
but my skateboard thinks otherwise..... :-)

I'd have to believe that any gain in precision will only
benefit the performance of your setup. It really comes down to if you think it'$ worth it or not??

Tod
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Paul Howard
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Paul's 2 Cents on Front Trucks (and Rear Trucks too)

Post by Paul Howard » Sat Apr 15, 2006 5:02 am

Hey, I pretty much use converted 8mm axle RT-X's in front for everything, 100mm for tight tight(but occasionally a Radikal on flat super tight) , 107's on tight/hybrid, and a 129mm for G/S and Super G. I find that 8mm conversions with straight axles just handle a little nicer plus having the hanger ends machined off to be exactly 90 degrees from the axle and machined locknuts with the right spacers between your bearings all makes a noticeable difference in the front as well as the back in terms of traction and speed. I agree, a tweaked and wedged RT-X in front is Saa-Weet for a lot of courses and it's simple.

As far as Splitfires, I have tried the Splitfire Phase III(same as Phase II but trimmed more) in front and it was good on a FAST highspeed course, but other wise I felt it wasn't twitchy enough for T/S or Hybrid for me even when pos wedged 15 and almost 20 degrees, but a lot of people do like them.

As a rear truck used on the Randall DOWNHILL baseplate, The Phase II and III hanger is a good slow action REAR truck for high speed or if you like a solid "dead"(in a good way) rear truck. However, the Phase I Splitfire with the Tracker RT-X baseplate is my definate 1st choice REAR truck for T/S and Hybrid. Fluitt should start making more soon, supposedly.

As far as Seismics, I never could get them to feel good for me in front, but as a REAR Truck, the Metal 30 degree baseplate with a 130mm hanger works like a charm for me on G/S, I have a 100mm hanger also I occasionally use as a REAR truck for T/S or Hybrid. Both were 8mm Wallgren/MMW conversions I bought from Dan at Seismic. Very solid.

Good Luck if you guys go to the Buckeye in June, I'm cancelling out due to a back injury, but hopefully I'll make it the DHB Dixie Cup #2.-Adios, Paul
I just dig slalom!

Matthew Wilson
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technical questions

Post by Matthew Wilson » Thu May 04, 2006 4:41 pm

Also posted at silverfishlongboarding.com

Ok, I am one of those poor, sorry-ass, newbie, dweebish skaters who got into this game way late and just look like a dumb fool anytime I step on a skateboard. With that said, I also slalom. Yes, slalom is cool to do, but it is still seemingly dweebish to some if that is all you do. And that is all I have done. So, I guess I'm dweebish.

Anyway...I need more traction on my back truck. Maybe I also need to learn to keep my weight better distributed over the rear truck, but we can get to that later. So, I have heard that 8mm axles are more precise than the stock axles that come on most trucks. I ride Tracker RTS's in the rear and will continue to ride that until appropriate funds come my way to buy a Splitfire or some other expensive gizmo that will help stick my wheels to the ground. Until then, I was considering the less expensive road of grabbing one of those modified RTS's from Sk8kings: http://sk8kings.com/Merchant2/merchant. ... ory_Code=T

They say that the axle is 5/16in. Yet all the hype I have heard is about 8mm axles because they allow for less slop between bearing and axle. And, though I am no math major, I know that 8mm = .315 inches and 5/16in, converted to decimal form is .3125. I also took machine drafting in high school and know that the difference between those numbers is not alot, but tolerances depend on application.

Wow, I take the long road to a point. So, does anyone care to educate my dumb self on this topic? If I buy a $45 modified RTS, am I gaining anything more than riding an $18-20 stock RTS? And when folks talk about 8mm axles, do they mean that the axle started at 8mm and was then machined down to 5/16", and because it was machined down it is more precise than a stock axle simple fabricated at 5/16"?

Thanks for your patience and feedback.
slalom is good

Paul Howard
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Matthew Wilson's Truck Question

Post by Paul Howard » Fri May 05, 2006 5:36 am

Hey, I looked on the www.sk8kings.com site and it did'nt really give the info I wanted to answer your question about buying them. Here's my thoughts:

8mm axles DO improve traction because they get rid of some slop, sloppy wheel jiggle is one of the reasons you will lose traction. However, it's really only good if the axle is truly straight. If a bent stock axle is pushed out of a hanger, then the hole it came out of is likely bent also. If you make a perfectly straight axle out of 8mm rod and cut threads on the ends and push it into the hanger's bent hole(likely from being cast around a bent axle), now you have a perfect BENT 8mm axle following the bent hole. You might get lucky and have a truck that has a straight stock axle and leave you with a straight hole, but not likely by my limited experience.


You also need to have the ends of the hanger and the axle nuts exactly shaved off to be 90 degrees to the axle so those surfaces don't cause "angular binding" on the bearings. With the right spacers between the bearings and with 90 degree hanger/axle/nut/bearing interfaces, you should be able to tighten that axle nut down pretty snug and have a free spinning wheel, this is almost non existant on a stock(misaligned) truck. Wallgren made(makes?) "monkey nuts" which are axle locknuts turned on a lathe with a "built-in aligned "speedring". I think(?) Wallgren also is who started lathed hangers with a lathe cut "built-in alighned speedring" bearing seat. He's sorta dropped his website I think. You can probably get his attention on the "Machine Shop/Truck" forum.


*****If Sk8kings is putting in a straight 5/16" axle and machining the ends of the hangers 90 degrees to the axle and using good axle nuts that are 90 degrees to the axle, then you are pretty well set. That extra amount of 8mm advantage is real, but not as big of an issue as good alignment and 90 degree hanger/axle/locknut interfacing. I would email them and ask them about those issues.*******


What I do next, is I take a stock RT-X or S to a machinist, have them push out the old stock axle, make me a new 8mm axle that is longer than the stock axle so that there is clean unthreaded axle under the entire length of the bearings so I have to use some kind of spacer or speed rings on the OUTSIDE of the bearings between the outer bearing and the locknut. This leaves you with pristine axle and no threads under your bearings. This will eliminate slop a little more.

Then, I take my empty hanger home and my newly made 8mm axle. I clamp the hanger in a vise and use a drill bit just a smidge bigger than 8mm and OVERBORE the hole just slightlty enough to let the 8mm axle slide in and out unimpinged.

I then put JB Weld metal epoxy into the hanger/onto the axle and put the axle into the hanger with masking tape over the portions that will be exposed sticking out of the hanger when centered in place. This will fill the empty space.

Next bake the hanger in the oven at about 175-200 degrees F for about 1-1.5 hours so the JB Weld hardens harder and a LOT faster. Don't go too hot or you'll change the temper of the aluminum of the hanger or boil the JB Weld and get bubbles.

Next, if you have a lathe, or an electric drill and a wheel with bearings and some clamps to improvise a lathe, get that hanger spinning on a nice medium speed(not too fast or it's imbalance will make it wobble around), and use your cutters or a metal file to carefully bring that hanger face to 90 degrees to the axle without dinging the axle, you can likewise do some work on the axle nuts to make them exact 90 degrees to the axle. Now you're set.

Finally, put a good 15 degrees of Pos wedge on that RT-X in front, about 10-15 degrees negative wedge on that RT-S in back(with some harder bushings also). If you have kinpins long enough for FULL HEIGHT BUSHINGS TOP AND BOTTOM (cone on top, barrel on bottom for the rear truck, cone on top and barrel or another barrel on bottom on the front truck). Khiro makes bushing combinations that fit what I just described. If you can't fit full height bushings top and bottom (like the new Indy's won't allow it), you can go to the hardware store and get a longer grade 8 3/8" bolt to replace the stock kingpin.

I do use the Phase I Splitfire(uses the RT-X baseplate) as a T/S and hybrid rear truck more than any other truck and prefer it over all others. S'posedly Fluitt is going to make more Phase I's and put them out in the near future. They are worth it. But so are Radikals front and back(IF you like the back truck to feel like that, some riders do and some riders don't) so I would recommend trying out every kind of truck you see on other people's decks before putting that kind of money into it.

Hopefully that's more usable info than confusion-Good Luck, Paul
Last edited by Paul Howard on Thu May 11, 2006 4:40 am, edited 1 time in total.
I just dig slalom!

Paul Howard
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Joined: Sat Dec 27, 2003 7:15 pm
Location: Corvallis, Oregon. USA

Paul Howard's Addendum for Matt Wilson

Post by Paul Howard » Mon May 08, 2006 2:20 am

I haven't seen the SK8KINGS rebuilt truck yet, but it's probably fine, if you don't find it too your liking, maybe contact www.asphaltplayground.com or Eric Wallgren by posting here, or on the "Machine SHop"(or whatever it's called) forum on the truck forum and see if either one of them have any RT-X/S's left. They might and they're who I learned a lot of info from that I previously wrote about. -Paul
I just dig slalom!

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