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Discussion Starter · #1 ·
Just finished up the weekend with two solid days of nothing but MX riding (my first two times at a MX track) and had a BLAST! Got to meet up with some cool peeps (Husker525, Terse, LittleMissE, RockiesYFZ, and others). Unfortunately the two days weren't without incident.. I cased pretty hard on 2-3 occasions throughout the two days of riding, and while the I didn't hurt much from the incident I just assumed the impact was pretty minor in comparison to what some of you guys might experience since I'm still a little timid (not afraid! :bawling: ) of railing the big stuff. Anyways..

I was doing some maint. work and cleaning the quad up from this weekends activities and had to remove the rear plastics to top off the rear coolant resivor. Upon reinstalling the rear plastics I noticed the left side rear fender was sitting up about 3/4" to an inch higher than the right.. Noticed the grab bar was crooked too. You can pretty much look down the subframe rails with the seat off and see the that somethings just not quite right.. And when looking at the bottom of the battery box you can see it's slightly overhanging over the chain.. That's not normal is it??

I did some poking around and found a picture that looks somewhat like my case. I didn't have my camera handy to snap a pic of mine, but this'll give you a good idea. Keep in mind the orignal thread that this pic was pulled from, it was determined that swingarm was the fault, not the subframe. If you noticed in the pic he's got a aftermarket tubular swingarm which was said to be "weaker" than the stock cast Al swingarm.. Anyhow, my swingarm is still stock (2008 model with LOW hours).

So here's kinda how mine sits:


I noticed there's a fair ammount of flex in the subframe if I pull up on the grab bar in attempt to "tweak" it back into shape. Not so much that it would suggest it was broken, but perhaps fatigued?

If it's bent, it's bent.. Nothing I can do about it now! :strokin: But really, how easily are these things bent? After looking at how much a stock one is, and aftermarket ones I'm a little trigger shy about purchasing a new OEM one with all the talk I've seen of how weak these things are. Especially if I bent the thing and I'm just getting started.

Granted these things were designed to tweak well before the frame.. But really..

Thoughts/Suggestions/Comments welcome...
 

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It's very likely that you bent it. The OEM subframe is cast aluminum and it doesn't take much to bend/break one. The subframe was one of the reasons that the first generation of Curtis Sparks pipes for the YFZ were bad about breaking. They had a solid fit where the pipe went into the canister, and the flexing of the subframe would eventualy break the pipe around that area. It was VERY common, so common at the time that Sparks was replacing/fixing the pipes for free.

If it were me, I'd look into an aftermarket alternative. In my opinion, the 6 point subframes are the best. I understand that with a lot of them, you have to weld the lower mounts on to the frame and you might not want to tear your quad down to do that. But there are some aftermarket 6 point subframes that are bolt on units, and I've heard they work pretty well but I don't have any firsthand experience with them. Another option would be to find some subframe braces. I know there used to be a couple of companies that sold them, and I've seen people make their own.

You are right though, the subframe is designed to break before the frame does. That's why I suggest either an aftermarket subframe with the lower mounts on it, or either an OEM subframe with the subframe braces. Gibson offers a stock replacement subframe that is made of chromoly, and it acts like a big lever attatched to the frame and since the subframe is stonger than the frame, guess what happens..............yep, the frame gets broken right below the subframe mounts. That's why I say the lower mounts are the key. With them, the subframe is supported in a way that won't let it bend down like a lever, so that much stress isn't put on the frame. Here's a pic of my Walsh 6 point so you can see what I mean about the lower mounts.


Sorry about the long @ss post, I kinda went on a little rant there. :loser:
 

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Discussion Starter · #3 ·
QUOTE (gtilley45 @ Feb 8 2009, 08:11 PM) index.php?act=findpost&pid=743919
It's very likely that you bent it. The OEM subframe is cast aluminum and it doesn't take much to bend/break one. The subframe was one of the reasons that the first generation of Curtis Sparks pipes for the YFZ were bad about breaking. They had a solid fit where the pipe went into the canister, and the flexing of the subframe would eventualy break the pipe around that area. It was VERY common, so common at the time that Sparks was replacing/fixing the pipes for free.

If it were me, I'd look into an aftermarket alternative. In my opinion, the 6 point subframes are the best. I understand that with a lot of them, you have to weld the lower mounts on to the frame and you might not want to tear your quad down to do that. But there are some aftermarket 6 point subframes that are bolt on units, and I've heard they work pretty well but I don't have any firsthand experience with them. Another option would be to find some subframe braces. I know there used to be a couple of companies that sold them, and I've seen people make their own.

You are right though, the subframe is designed to break before the frame does. That's why I suggest either an aftermarket subframe with the lower mounts on it, or either an OEM subframe with the subframe braces. Gibson offers a stock replacement subframe that is made of chromoly, and it acts like a big lever attatched to the frame and since the subframe is stonger than the frame, guess what happens..............yep, the frame gets broken right below the subframe mounts. That's why I say the lower mounts are the key. With them, the subframe is supported in a way that won't let it bend down like a lever, so that much stress isn't put on the frame. Here's a pic of my Walsh 6 point so you can see what I mean about the lower mounts.


Sorry about the long @ss post, I kinda went on a little rant there. :loser:[/b]
No need to applogize! :icon_biggrin: I'm all for posts that explain things, in detail rather than some one liners you know..

My first instict was that the subframe was bent.. Looking at it, you can see the front (frame, ect) part of the quad is true, and its the "tail" that begins to distort over the length of the subframe and by the time you look at the grab bar it's clear something is tweaked. Reading some stuff here (specificly the thread I nabbed that pic from) had me starting to worry my swingarm might have been tweaked, but from what I see I'm pretty confident it's the subframe, especially reading about how many people tweak theirs. I knew they were on the weaker side, but never wrecking my quad I was pretty certain I'd not bend it unless I had done something stupid..

Interesting.. That these things bent so easily.

I've looked through quite a few threads and saw the braces mentioned and that looked like an interesting option. Seems more like a band-aid type fix though depending on the braces lower mounting location. Of course I'd like a "bolt-on" solution, but I'd really rather not compromise the frame just to save a little cash/headache now only to end up investing A LOT more later.. Then again this is kinda a bummer, as I was going to enter in the SRAC racing series and do my first season of racing this year, but I'm going to miss a fair bit of the season if I'm stripping the bike and having the mount (might as well gusset it while I'm in there) welded to the frame and re-powder coating everything. Hmm...

Forgive my ignroance, but can you point me into a direction where I can see how a "bolt-on" 6pt subframe actually attatches to the frame?
 

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QUOTE (JustDSM @ Feb 8 2009, 09:39 PM) index.php?act=findpost&pid=743930
I'd really rather not compromise the frame just to save a little cash/headache now only to end up investing A LOT more later.. Then again this is kinda a bummer, as I was going to enter in the SRAC racing series and do my first season of racing this year, but I'm going to miss a fair bit of the season if I'm stripping the bike and having the mount (might as well gusset it while I'm in there) welded to the frame and re-powder coating everything. Hmm...

Forgive my ignroance, but can you point me into a direction where I can see how a "bolt-on" 6pt subframe actually attatches to the frame?[/b]
Well, it sounds like you have the right attitude about this anyway.

But yes, if you're gonna be racing and have the quad down to the frame, I think you should go ahead and gusset it. I've heard of people having good luck out of the bolt on's but I don't have any firsthand experience with them. The only ones I've had my hands on are a Walsh 6 point, a LSR 4 point (uses only the top OEM mount, and the weld on lower mount), and a JH Racing 6 point.

I THINK the JB Racing subframe is a bolt on. I looked at their website and it doesn't help. It only says "YFZ450 subframe" and doesn't have a picture. But for some reason I'm thinking it bolts to the bottom fender brackets.
 

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Discussion Starter · #7 ·
QUOTE (gtilley45 @ Feb 8 2009, 08:51 PM) index.php?act=findpost&pid=743938
Well, it sounds like you have the right attitude about this anyway.

But yes, if you're gonna be racing and have the quad down to the frame, I think you should go ahead and gusset it. I've heard of people having good luck out of the bolt on's but I don't have any firsthand experience with them. The only ones I've had my hands on are a Walsh 6 point, a LSR 4 point (uses only the top OEM mount, and the weld on lower mount), and a JH Racing 6 point.

I THINK the JB Racing subframe is a bolt on. I looked at their website and it doesn't help. It only says "YFZ450 subframe" and doesn't have a picture. But for some reason I'm thinking it bolts to the bottom fender brackets.[/b]
I've just learned over time that it's better to spend a little more and do it right the first time.. If you know anything about the DSM part of my screen name you'll understand :mhihi:

I'm pretty certain that MX is something that I'll be getting into pretty heavily among the other types of riding I do. This weekend of riding really got me hooked! So I guess I need to start making preperations... From what I am seeing, it's not so much the number of mounting points (as long as it's more than just two LOL), but the key is the lower mounting point, as that's what is going to bear the brunt of the force placed on the subframe.

I'm going to check out the Walsh/LSR subframes and see what gives me the warm and fuzzy.. I checked out the JB site too, and they must be under construction there as there's hardly any content there..

Thanks for your input!
 

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QUOTE (JustDSM @ Feb 8 2009, 09:59 PM) index.php?act=findpost&pid=743943
I'm pretty certain that MX is something that I'll be getting into pretty heavily among the other types of riding I do. This weekend of riding really got me hooked![/b]
Yeah, MX has a way of doing that. :icon_cool:


QUOTE (JustDSM @ Feb 8 2009, 09:59 PM) index.php?act=findpost&pid=743943
From what I am seeing, it's not so much the number of mounting points (as long as it's more than just two LOL), but the key is the lower mounting point, as that's what is going to bear the brunt of the force placed on the subframe.

I'm going to check out the Walsh/LSR subframes and see what gives me the warm and fuzzy.. I checked out the JB site too, and they must be under construction there as there's hardly any content there..

Thanks for your input![/b]
You are 100% correct, the main thing is the lower mounts. Like you said, they handle most of the force that the subframe will see.

Before you even start shopping, the Walsh will probably be higher. :icon_neutral: Walsh makes some good stuff (the best in my opinion), but it sure ain't cheap!!

Here you go, I dug up a couple links for you.....
Walsh 6 point
LSR 6 point **Does not work with OEM rear shock
LSR 4 point
http://www.triumphmotorsports.com/subframes.htm
 

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Hey Justin, first.... please remind me about bringing the NCVQ to the dyno for you or I very well might forget... I'm old that way! :mhihi: Bring some main jets and pilot jets too if you have any. I'll bring mine as well...no worries :)

I am sure it is your sub frame, and as Grant has posted everything he says is right on the money! So I have very little to add other then I can check it out for you and offer my suggestions for you and what I think will work for what you need.

Also if weather is going to be crappy we can always re-schedule the dyno time. I see snow and such this week, so don't think it is set in stone :)

I also want you to show me how you filled up your radiator too when you started the motor for the first time. I might have an idea as to what happened. YES it's fine! :mhihi:
 

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Discussion Starter · #10 ·
QUOTE (Terse @ Feb 8 2009, 09:26 PM) index.php?act=findpost&pid=743956
Hey Justin, first.... please remind me about bringing the NCVQ to the dyno for you or I very well might forget... I'm old that way! :mhihi: Bring some main jets and pilot jets too if you have any. I'll bring mine as well...no worries :)

I am sure it is your sub frame, and as Grant has posted everything he says is right on the money! So I have very little to add other then I can check it out for you and offer my suggestions for you and what I think will work for what you need.

Also if weather is going to be crappy we can always re-schedule the dyno time. I see snow and such this week, so don't think it is set in stone :)

I also want you to show me how you filled up your radiator too when you started the motor for the first time. I might have an idea as to what happened. YES it's fine! :mhihi:[/b]
Yeah, I can't believe I forgot to give you those two needles at Watkins.. I guess we all kinda got caught up in the moment.. I know I was just all sorts of excited to actually be out riding on the track with some good people. I'll remind you :) as I'd like to get that James Dean needle out.

I too am pretty certain it's the subframe. Tomorrow morning I'm going to put the frame on a stand just to confirm it's not my swingarm or anything else. I'm just anal.. It's pretty clear just by looking at the subframe the thing is just tweaked. Ohh well.. Yeah, big thumbs up for Grant and his help!

I'm a die hard. A little snow isn't going to stop me. And judging from the pictures you've posted in the past, the snow wont keep you from the Dyno either. But in any event, if for some reason it's an issue for you, I won't be butt hurt if we have to reschedule. But I fully plan on making it irregardless if all is good on your end.

And I just want to be sure.. Is my motor ok? :neener:

It might have been my first time MX'ing but I've filled up a radiator or two!! I promise!! I'm not going to lie I was FREAKING OUT when I noticed the coolant drain bolt finger tight and my skid plate soaking wet. I am going to formally say "I'm Sorry!" for freaking out via txt message on you :bowdown: This thing is my baby!
 

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The JB racing subframes attach to the frame where the bottom chain roller is on the inside of the frame on the left side and on the right side they attach through the foot peg hole, also on the inside of the frame. The JB subframes are a great alternative to having to weld somthing on your frame, but if you are goin to be gusseting your frame anyways might as well just do that.

And like grant said, braces are also a good alternative, that is if your subframe is still salvagable. I know that JB, Walsh, ATVfourplay make them.

Shawn
 

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I'll explain air bubbles and how I fill up the radiator to you at the dyno :icon_cool:

Snow won't stop me... however I want it tuned in at a certain temps so it isn't tuned for a crazy cold unridable temperature. But I think it should be fine.

No worries!! :icon_biggrin:
 

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Discussion Starter · #13 ·
QUOTE (quadracer2 @ Feb 8 2009, 10:02 PM) index.php?act=findpost&pid=743986
The JB racing subframes attach to the frame where the bottom chain roller is on the inside of the frame on the left side and on the right side they attach through the foot peg hole, also on the inside of the frame. The JB subframes are a great alternative to having to weld somthing on your frame, but if you are goin to be gusseting your frame anyways might as well just do that.

And like grant said, braces are also a good alternative, that is if your subframe is still salvagable. I know that JB, Walsh, ATVfourplay make them.

Shawn[/b]
Sounds like the JB bolt-on subframe is a little sturdier than just mounting to the fender brackets as it was mentioned earlier. I'll look into it. I'd like to see it mounted, so if you know of any pictures of it mounted to the frame please feel free to post them here. I'll keep an eye out for a pic or two myself..
 

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Discussion Starter · #14 ·
QUOTE (Terse @ Feb 8 2009, 10:09 PM) index.php?act=findpost&pid=743988
I'll explain air bubbles and how I fill up the radiator to you at the dyno :icon_cool:

Snow won't stop me... however I want it tuned in at a certain temps so it isn't tuned for a crazy cold unridable temperature. But I think it should be fine.

No worries!! :icon_biggrin:[/b]
I promise you I know how to burp the coolant system! :icon_biggrin: The drain bolt I tell ya!! :)

Yeah.. Like we discussed previously.. I agree on the temperature deal.. I remember the temp you mentioned, but what kind of variance can we work with and still be "good to go"?
 

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OK cool! I'm anal too!! :mhihi:

20*-30* swing.

And...






































































Your motor is fine! :neener:
 

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I tried to find some pictures of it and this is the best I could do. On the right side of the frame you have to drill the frame out through the top foot peg mount and run a longer bolt through the fraim rail. And on the left side you just use your chain roller and a bolt. Hope this helps.

 

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Discussion Starter · #17 ·
That does! Thank you very much for taking the time to dig that up.
 

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QUOTE (JustDSM @ Feb 8 2009, 11:11 PM) index.php?act=findpost&pid=743989
Sounds like the JB bolt-on subframe is a little sturdier than just mounting to the fender brackets as it was mentioned earlier.[/b]
I didn't mean it mounted to the brackets themselves, I thought it bolted to the frame where the brackets attatched to the frame. There's a guy that races around here that had one of the JB subframes, and I thought he told me it attatched like that. Oh well, you've got it straight now. :clap:
 
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