So I'm working on a Thunderace swingarm conversion, and trying to figure out which direction I want to go with a rear wheel. I've looked at several threads where the crush drive was modified, along with other parts, so as to get the rear sprocket to align with the front. I can't help wondering if it wouldn't be easier to just use an offset sprocket. The crush drive is there to serve a purpose, so why mess with it?
Am I missing something obvious?
If you deviate from Marc's installation shown here:
http://www.fjmods.btinternet.co.uk/MarcRittner.htm (http://www.fjmods.btinternet.co.uk/MarcRittner.htm)
According to Marc's measurements, the unmolested cush drive will add 0.195" to the outward offset on the chain in relation to the counter shaft sprocket.
Therefore, instead of using the oem Honda VF1000 offset sprocket, which has a offset of 0.070", you will need to special order a custom sprocket with a offset of 0.195+0.70= 0.265"....or about ~1/4" offset on the counter shaft sprocket.
I believe Sprocket Specialists can make you such a sprocket. Don't forget to specify the sprocket's countersink relief necessary for the bolt and locking tab to fit on the shaft. I would go ahead and order custom 2 sprockets to have 1 on hand when time comes to change out the worn custom sprocket.
What is unclear to me, is what this 1/4" outward offset will do to the clearance of the 530 chain inside your c/s cover. You may need a XJR sprocket cover.....others can chime in here..
On the plus side, you will have more room between your chain and the back tire.
Hope this helps. Cheers!
I can give some insight here... I mounted a 1/4" offset sprocket from PBI and indeed the stock engine cover would not clear it. Randy sold me a kit for the XJR cover that included a longer clutch push rod and a longer shift shaft. The XJR cover has a corner on it that must be removed to easily go on and off past the FJ frame. I used a hand held grinder and just buzzed the thing- no sweat. The result was a totally stock looking engine with the 8mm wider cover, push rod and shift shaft. None of the parts were difficult to instal the clutch basket did have to come off though. It was an opportunity to get those wire like clutch retainer deals out though.
Once the offset sprocket was done I was able to mount a 6" wide wheel with no clearance issues at all. I felt like this process was easier than machining a hub or cush-drive.
Do it- you will be happy!
tim
http://www.fjowners.com/index.php?topic=3148.60 (http://www.fjowners.com/index.php?topic=3148.60)
Very cool Tim, thank you....Your bike is sooooo bitchen. It was great to meet you in Porterville. :good2:
I already have the VF1000 sprocket on the bike. In reading my original post again, I wasn't too clear. I was refering to the possibility of using an offset rear sprocket. If I have to machine stuff, it just seems more logical to me to machine what I need to offset the sprocket. Modifying the crush drive seems to me the equivelent of cutting a coil spring to lower your car. It works, but I wouldn't think it's really the best way to do it.
Something like this
(http://img542.imageshack.us/img542/9708/sprocketoffset.jpg) (http://imageshack.us/photo/my-images/542/sprocketoffset.jpg/)
Quote from: Pat Conlon on June 15, 2012, 04:21:20 PM
Very cool Tim, thank you....Your bike is sooooo bitchen. It was great to meet you in Porterville. :good2:
Thanks Pat- really good to meet you and the others guys too. I had a great time! Wish I could have gone on to CO but it wasn't in the cards- next year though!
Rosso75- careful with the rear offset as no matter which end you offset you have to deal with the issues it creates. The countershaft sprocket can be done with the method and kit I used- not sure how you would deal with the clearance of the rear sprocket next to the swingarm... Anything can be done if you think it through and man are you going to love the updated wheels!
Keep at it!
tim
Quote from: axiom-r on June 15, 2012, 08:14:16 PMnot sure how you would deal with the clearance of the rear sprocket next to the swingarm
The object would be to offset the sprocket inward, rather than cutting / machining the crush drive. The swingarm wouldn't be an issue.
Quote from: rosso75 on June 15, 2012, 07:07:48 PM
If I have to machine stuff, it just seems more logical to me to machine what I need to offset the sprocket.
You will only have to machine the cush drive once..... rear sprockets, on the other hand, need replacing....
Do you want to go thru this exercise every time you need a new rear sprocket? Do it once and get it over with.
Rosso,
I think there is a minor misunderstanding. You are in no way removing the cush drive nor changing it's function at all. You are merely machining the mounting surface for the sprocket by a small amount. If you really wanted to get into it, I'd say it would minutely IMPROVE the way the cush drive operates due to putting less of a side load on it by moving the sprocket slightly inboard.
This mod has been very thoroughly researched - and I'll also say that when Marc Rittner "re-did" this mod, he was very meticulous. If you need further verification of his thoroughness when modding things - you should see his 200 mph Aprilia - the fastest 2 cylinder motorcycle in the standing mile - anywhere.
Offset countershaft sprockets are an option - and really needed for a 6 inch rim. An offset rear wheel sprocket would be a one-off part to solve a problem that does not exist.
Cheers, :drinks:
Chris
Quote from: rosso75 on June 15, 2012, 08:38:37 PM
Quote from: axiom-r on June 15, 2012, 08:14:16 PMnot sure how you would deal with the clearance of the rear sprocket next to the swingarm tire
The object would be to offset the sprocket inward, rather than cutting / machining the crush drive. The swingarm wouldn't be an issue.
:unknown: Got ya- I was thinking of that the wrong way- but the issue is the same only with the other side (tire side). The offset rear sprocket is an interesting approach. I have not read about anyone having done it that way yet... I would check to see if you can get a small enough sprocket and still get the offset you need- they are mostly for dirt bikes and therefore have a higher tooth count I think. I dropped to a 38 tooth in the rear and I need to go lower still to get the RPM's back down to where they were stock at 70MPH. Even though you are fitting a larger rim the over all wheel diameter with modern rubber mounted will drop slightly compared to stock FJ's - this will raise your RPM's and fuel economy.... gotta adjust for that in your gearing. If you mount that 44 tooth (shown) she's going to be a monster off the line but no fun to ride for the whole weekend!
tim
I find it interesting that I got all this response, and all these suggestions, and nobody even knows (or asked) what wheel I'm using. As I mentioned in the original post....I'm trying to figure out what direction I want to go with a rear wheel. The logic of the question was simply, in a perfect world, wouldn't it be better to keep the cush drive intact?
Anyway....
I know there are several wheels that are bolt-in, or close to it with some mods. Me personally, I tend to go with the "make what you got fit" approach, rather than the "buy more parts" approach. I just happen to have an '03 954rr wheel laying around, so that's what I'm working on.
Among other things, my concern right now is the width of the wheel and the alignment of the sprockets. I know...useless without pictures. I'll try and post them tomorrow. My concerns regarding the cush drive are still legit, I think, especially now that I've taken the stock FJ wheel apart. The rubber dampers in that hub are HUGE, especially on the power side. I'm assuming it was engineered as such due to the FJ's torque.
That being the case, I just can't justify modifying what would already be a smaller cushion against driveline shock. Every wheel mod I've seen already has smaller rubber in the cush drive, and in some cases you wanna cut them down further? It may work, but what kind of stress are you putting on other driveline components? As I said, I'm of the opinion that the cush drive serves a purpose, so why screw with it if you have the option of offsetting the sprocket instead?
I'll get pics up. It just happened to be on my mind at the moment, so I figured I'd post up something.
I appreciate all the input
Quote from: rosso75 on June 15, 2012, 01:18:29 PM
So I'm working on a Thunderace swingarm conversion, and trying to figure out which direction I want to go with a rear wheel.
^^ This was your opening statement.
Pardon me. I assumed that you were also using a T-Ace wheel with the oem bearings for correct axle diameter which fits the axle blocks which fits the swing arm....
Re: Altering the cush rubbers; I agree with you.....We never told you to do that. Again, in the Mark Rittner write up, it clearly shows that you don't alter the cush rubbers at all. You simply remove 0.195" from the *face* of the cush drive....where the sprocket sits (you gotta remove the sprocket studs first)
Re: Offset sprocket; My point was simply that this step, shaving the outside face of the cush hub, is no big deal. You only need to do it once.
If you plan on using a different rim (sounds like you are) all bets (and measurements) are off.
Best of luck.
should look great once fitted , what width is that 5.5" ?
6 inch.....190/50-17
sweeet , will be awesome , one fat arse end
I tore the bike down and had the frame powder coated a low gloss black, along with the swingarm, and about 15 other pieces. The CBR wheel is also a low gloss black, and it looks really nice in mock up. I'm working on a paint scheme that will be a traditional Yamaha yellow, black, and white. The black will be a combination of gloss and flat.
Current issue, aside from the sprocket alignment which I think I can fix, is the axle. The Thunderace uses a 28mm axle. The CBR uses a 25mm axle. I can't use the CBR axle with the Thunderace swingarm because the axle isn't long enough (13 inches). I'm looking at a couple axles on eBay that should work. One is from a '00 ZX6 (25mm x 13 3/4"), and the other is from an '07 ZX14 (25mm x 14"). They're both the same price, so it's gonna depend on whether one of them has chain adjusting blocks that will fit in the Thunderace swingarm, rather than me having to make new ones.
On that note, if anybody has one of those two bikes, I'd appreciate if you could measure the slot in your swingarm where the adjusting blocks sit and let me know what the height is. I seem to recall that the slot in the Thunderace arm is 45mm.
Beyond that, I'm sure I'll have brake caliper issues, but I'll cross that bridge when I get there.
guessing they don't make the size bearings that would solve the issue , maybe use 3mm shims in the bearings you have
Gotta say I also thought you were doing the Thunder Ace conversion. I can tell you with some certainty that if you are mounting a 6" rim you are almost certainly need to go with an offset countershaft sprocket and the XJR countershaft sprocket cover with associated longer clutch pushrod and shift shaft.
I eliminated the need to make custom spacers for placement of the wheel on the rear axle by using the entire rear end from an R1. You will have to do some custom spacer work for the wheel placement I assume and this gives you another variable to adjust for a perfect alignment. This could be a life saver or a pain in the ass.
My advice would be to go straight to the XJR cover and accept it - that way you don't necessarily machine the wheel at all and nearly all of the work is bolt on.
Regarding the axle issue... I source custom bearings all the time from a local electric motor shop. I can get virtually any size bearing from them. Perhaps a set of custom bearings for the rear wheel will resolve the axle selection for you?
tim
Yes. Different bearings and new spacers may be the way to go. would allow use of the ace axle. A bit of machining to be done though.
I thought about putting different bearings it it, but the problem is that I don't have the Thunderace axle. All I have is the swingarm. If I've gotta buy an axle, might as well just get one that fits the bearings in it now. Besides, I don't see any Thunderace axles on eBay currently
I have the VF1000 sprocket on it now, but I need a little more offset to clear the tire. Obviously I'll have to work that out, but it will give me more flexibility with where I locate the rear sprocket.
This is the reason I'm reluctant to use any wheel that requires modifying the rubber in the cush drive. The dampers in the FJ are huge compared to pretty much any other wheel one would use, so the ability to absorb driveline shock is already reduced. I know, there are wheels to use that don't require modifying the rubber, but like I said, this CBR wheel is what I've got laying around....free, and in hand. Besides, it's more fun to figure out something new.
(http://img862.imageshack.us/img862/8931/cushn.jpg)
(http://imageshack.us/photo/my-images/862/cushn.jpg/)
Quickie shot of the wheel / swingarm. I'll have some better pics, probably in a project thread, when I get the issues with the wheel worked out.
(http://img405.imageshack.us/img405/5473/wheele.jpg) (http://imageshack.us/photo/my-images/405/wheele.jpg/)
Quote from: rosso75 on June 25, 2012, 12:41:29 PM
I thought about putting different bearings it it, but the problem is that I don't have the Thunderace axle. All I have is the swingarm. If I've gotta buy an axle, might as well just get one that fits the bearings in it now. Besides, I don't see any Thunderace axles on eBay currently..."
You will wait a long time for T-Ace parts on the US eBay....
As far as I know, the T-Ace (YZF1000R) was available in the US for only one year.
The UK eBay is where you should look. The T-Ace had a long run in the UK and lots of used parts are still available.
The T-Ace axle is still available new from Yamaha for ~$45
http://www.powersportsplus.com/parts/search/Yamaha/Motorcycle/1997/YZF1000RJ/REAR+WHEEL/parts.html (http://www.powersportsplus.com/parts/search/Yamaha/Motorcycle/1997/YZF1000RJ/REAR+WHEEL/parts.html)
I have a extra T-Ace wheel if you are interested.....
Quote from: rosso75 on June 25, 2012, 12:41:29 PM
This is the reason I'm reluctant to use any wheel that requires modifying the rubber in the cush drive. The dampers in the FJ are huge compared to pretty much any other wheel one would use, so the ability to absorb driveline shock is already reduced. I know, there are wheels to use that don't require modifying the rubber, but like I said, this CBR wheel is what I've got laying around....free, and in hand. Besides, it's more fun to figure out something new.
Am I missing something or are you? The machining of the cushdrive to bring the rear sprocket closer to the rear rim does not impact the rubber bits in anyway as far as I know... Is there some mod that requires the rubbers be changed out?
tim
Quote from: axiom-r on June 25, 2012, 02:30:29 PM
Am I missing something or are you?
Entirely likely it's me. I bought this bike in April '09, then took it apart in June '09 for a quick paint job. It's been in project form ever since, due to a ridiculous work schedule at the time, and moving 3 times in 3 years. I'm trying to recolect from foggy memory.
However, I seem to recall seeing a thread that involved using a wheel that requires cutting down the thickness of the rubber. I'll see if I can find it again.
As for the axle....
If I get a new one for $45, I don't know what else is gonna nickel and dime me....the nut, washer, spacers, etc. The two axles I'm looking at on eBay are each less than $20 shipped, and include all that stuff.
If you scroll down to the part about using an FZR1000 wheel, the article explains that you have to shave 5-7mm off the cush drive rubber. There's a pic in there.
http://www.fjmods.btinternet.co.uk/Wheels.htm (http://www.fjmods.btinternet.co.uk/Wheels.htm)
your right, thats what the article says (popcorn)
Ohhhhh Yeah - I do recall that now- but that is just shaving them down on the side that doesn't matter in order to accommodate the mod- its a minor amount. I never considered that reduction to be a threat to the cushdrive because the rubbers stay the same length all along the side that the force is absorbed on.
PS- I might have a spare Thunderace rear axle for you. I do have an 07 R1 swingarm already modded to mount on an FJ and the rear axle set too. I'll check my stash.
Quote from: Pat Conlon on June 15, 2012, 02:34:38 PM
If you deviate from Marc's installation shown here:
http://www.fjmods.btinternet.co.uk/MarcRittner.htm (http://www.fjmods.btinternet.co.uk/MarcRittner.htm)
According to Marc's measurements, the unmolested cush drive will add 0.195" to the outward offset on the chain in relation to the counter shaft sprocket.
Therefore, instead of using the oem Honda VF1000 offset sprocket, which has a offset of 0.070", you will need to special order a custom sprocket with a offset of 0.195+0.70= 0.265"....or about ~1/4" offset on the counter shaft sprocket.
I believe Sprocket Specialists can make you such a sprocket. Don't forget to specify the sprocket's countersink relief necessary for the bolt and locking tab to fit on the shaft. I would go ahead and order custom 2 sprockets to have 1 on hand when time comes to change out the worn custom sprocket.
What is unclear to me, is what this 1/4" outward offset will do to the clearance of the 530 chain inside your c/s cover. You may need a XJR sprocket cover.....others can chime in here..
On the plus side, you will have more room between your chain and the back tire.
Hope this helps. Cheers!
Do you know what sprocket he used on the back wheel
The Thunder Ace wheel uses the same sprocket as our FJ's, just flip the sprocket around so that the offset faces the inside...
Thanks for that Pat,saved me €100.I got back end from UK minus sprocket,I was'nt sure if it needed the Ace one.
You got it laddie, we are always happy to help.
With the money you saved, why not donate a couple of Euros to Marsh to help run this forum?
Quote from: Pat Conlon on July 09, 2012, 12:49:02 PM
You got it laddie, we are always happy to help.
With the money you saved, why not donate a couple of Euros to Marsh to help run this forum?
Done
For the sake of anybody searching wheel mods in the future....
I got a ZX14 axle on eBay, delivered today, for $15. It's the correct 25mm diameter, and is wide enough to span the width of the Thunderace swingarm. The chain adjusting blocks need to be milled down a little, though that may be due to the added thickness of the powdercoating in the adjusting slot. I'll check it when I mount it.
I still have no idea what I'm going to do about a rear brake, or what problems I'll encounter, but that's the fun, right? :crazy: