putting a bigger tire and penske shocks on

[SethO]

I am running in the salt flats in a week and am looking to get more speed on top, when I put the new kumdo on (got 7800 miles with 4 BIR quarter mile drags out of it and could have gotten more but it was dicey in the rain) I got 5-8 mph on the top, plus with the directional tread intact still it was wayyy better, the worn shocks were not as big of an issue, the penske's just got here so I will be throwing them on.

I also have a 215/60/r15 with directional tread I am going to rip my fender off so I can get this on here. My theroy on this is that the taller tire will give me more top end in a straight line (like the salt flats) A shorter tire would help in the quarter mile drags I have found.

Wondering if anyone else was crazy enough to try this?

I understand this is a guess on if the spyder has enough power and torque to pull this off, the new tire weights 27 pounds and the standard weights 24 SO,,

 

[NancysToy]

You may have trouble with the VSS, unless you disable the wheel sensors. That's the theory, anyway. Not sure how the computer will react when it thinks the rear tire is rotating slower than the fronts.

 

[bone crusher]

You may have trouble with the VSS, unless you disable the wheel sensors. That's the theory, anyway. Not sure how the computer will react when it thinks the rear tire is rotating slower than the fronts.

Agreed...plus, the computer will not register proper mph as it's computing based on the standard tire size...this should only apply if the actual size of tire is different...for example, going from a 14 to a 15 or 16 inch tire...

 

[tjfischer]

You may have trouble with the VSS, unless you disable the wheel sensors. That's the theory, anyway. Not sure how the computer will react when it thinks the rear tire is rotating slower than the fronts.

Agreed...plus, the computer will not register proper mph as it's computing based on the standard tire size...this should only apply if the actual size of tire is different...for example, going from a 14 to a 15 or 16 inch tire...

Actually the VSS will have no Idea of a tire size change. The speed sensors are set closer to the center of the hub, not the outside of the wheel. Worst case scenario, the Speedometer may be off by a bit.

 

[bone crusher]

Actually the VSS will have no Idea of a tire size change. The speed sensors are set closer to the center of the hub, not the outside of the wheel. Worst case scenario, the Speedometer may be off by a bit.

Being that's one of Seth's concerns, if the speedometer is off, that does affect his racing, I presume...

 

[tjfischer]

SethO; Why did you decide to go with the Penske Shocks? I am currently awaiting the arival of my ELKA Shocks. I hoping they show up before my big ride next week. I ordered the Elites for both the front and rear.

http://www.elkasuspension.com/products/canam-moto.html

 

[SethO]

SethO; Why did you decide to go with the Penske Shocks? I am currently awaiting the arival of my ELKA Shocks. I hoping they show up before my big ride next week. I ordered the Elites for both the front and rear.

http://www.elkasuspension.com/products/canam-moto.html

They are the best, eviozone sold them to me, I did not know about the elka shocks when I ordered them and I am not going to F a company that has helped me go faster. The penske shocks are not on yet so I can't say either way but from a looks standpoint the are outstanding. They are made for you weight and how you ride.

the speedo will be off but I will have one of my cop buddies gun me to see the error and do the math.

On a trip side note Tom from NM is helping me out with the trip, I would really like to say thanks on here to him, he did not have to do what he did. Thanks bud, any time you want to come up and hunt or fish(that is what people come up here to do) you have a place to stay.

 

[NancysToy]

Actually the VSS will have no Idea of a tire size change. The speed sensors are set closer to the center of the hub, not the outside of the wheel. Worst case scenario, the Speedometer may be off by a bit.

In reality, it will. The rear wheel will now revolve farther with each revolution, and thus slower at the sensor or the wheel rim, either one. It will no longer match the rate that the front sensors see. Whether this affects the VSS remains to be seen. It is known that it does not like the rear turning faster than the fronts.

 

[tjfischer]

They are the best, eviozone sold them to me, I did not know about the elka shocks when I ordered them and I am not going to F a company that has helped me go faster. The penske shocks are not on yet so I can't say either way but from a looks standpoint the are outstanding. They are made for you weight and how you ride.

We are at the same point, awaiting upgrades. I ordered the ELKA's for handling, control and smoothing out the ride. ELKA builds them the same way, to match your driving style and weight. I'm just hoping I can get them on before I leave on my big trip.

I don't know if you will be in Gatlinburg. If you are I would like to compare the shocks and ride experiences with them. If not maybe we can meet on my way back, and go for a ride.

the speedo will be off but I will have one of my cop buddies gun me to see the error and do the math.

The speedo will be off because of the different size tire. I don't think the shocks will change anything.[/quote]

On a trip side note Tom from NM is helping me out with the trip, I would really like to say thanks on here to him, he did not have to do what he did. Thanks bud, any time you want to come up and hunt or fish(that is what people come up here to do) you have a place to stay.

Thats cool. Its good to know people who understand your passion and help out.

 

[Dochands]

Elka and the Penske shocks are an interesting mod. How do they compare in price?

 

[Magic Man]

The VSS will indeed see the slower turning rear wheel, and may or may not even go into limp mode. It could also cause a problem when on the brakes, as it will see the slower turning rear wheel and think it is beginning to "lock up" and therefore release the rear brake trying to get it back to the same turning speed as the front.

This could (in some cases) cause the bike to "swap ends" under hard braking from high speeds as the VSS may reduce, if not totally release the rear brake "trying to get it up to the same speed" as the fronts are turning.

At high speed with no rear braking force the rear end might want to "come around" as I have been told the salt flats are really kind of slippery?

The only way any of this can be found out "true or false" is to do some R&D testing with this set-up?

But remember, sometimes the "D" in R&D is for "Destruction." So I'd be very careful doing anything like this whatsoever!

Because, by the time you find out it's a problem it could be too late!

MM

 

[SethO]

The VSS will indeed see the slower turning rear wheel, and may or may not even go into limp mode. It could also cause a problem when on the brakes, as it will see the slower turning rear wheel and think it is beginning to "lock up" and therefore release the rear brake trying to get it back to the same turning speed as the front.

This could (in some cases) cause the bike to "swap ends" under hard braking from high speeds as the VSS may reduce, if not totally release the rear brake "trying to get it up to the same speed" as the fronts are turning.

At high speed with no rear braking force the rear end might want to "come around" as I have been told the salt flats are really kind of slippery?

The only way any of this can be found out "true or false" is to do some R&D testing with this set-up?

But remember, sometimes the "D" in R&D is for "Destruction." So I'd be very careful doing anything like this whatsoever!

Because, by the time you find out it's a problem it could be too late!

MM

this was a total F, got to switch the tire back, goes into limp mod (tranny, abs, some other dumbass warning) after about 1 minute of riding. If I had more time I would take the senors off or run with bigger front tires. I think I could have gotten more on the top with the extra 1.5'' of tire diameter but that will have to wait for another day.

the penske shock review will have to wait one more day(its not a seth test if it is not in the triples), was working on the spyder and helping out a kid that bought a honda RC51 but then I found out had never road a bike in his life since 8 this morning and I have to work from 530 to 5am. I ran out of time before work to switch the tire back at the dealership, lakeland motorsports who is not a spyder dealer but has helped me out a TON. They even called can am to tell them I was racing out there which can am answered it was not a big deal to them.

Also going to tape off the inlet holes in the front, and may do a run without the windshield, got 5 runs to do and I am racing one more quarter mile night and have it setup as close to the setup as I can to get.

I also need another belt if someone has one on the way. I have had a clean hole in it since 6k ( have 16k now) and I would like to be able to have one just in case. the dealer I got my spyder from needed to order one so it would not get here in time.

I will get some pics up here in a bit

 

[NancysToy]

Seth, sorry the tire didn't work out. A couple of us has suspected trouble. Thanks for proving it out for certain. Wondering a bit why you want to try a bigger tire. I know we can't change the gearing, but my experience has been that unless you are running at redline (or the top of the power curve) well before the traps, that a taller tire won't help. We only did this when there was no gear left back in days gone by.

 

[SethO]

Seth, sorry the tire didn't work out. A couple of us has suspected trouble. Thanks for proving it out for certain. Wondering a bit why you want to try a bigger tire. I know we can't change the gearing, but my experience has been that unless you are running at redline (or the top of the power curve) well before the traps, that a taller tire won't help. We only did this when there was no gear left back in days gone by.

had to be sure, I gained at least 5mph with a new rear tire so I was testing the idea, I think the red line in 4th would get there being taller, 5th is like overdrive in the wind or up a hill. here are some pics.

 

[tjfischer]

had to be sure, I gained at least 5mph with a new rear tire so I was testing the idea, I think the red line in 4th would get there being taller, 5th is like overdrive in the wind or up a hill. here are some pics.

Dude, I'm really sorry that it didn't work out.

I don't know if it is doable or not. But perhaps your dealer can adjust the ECM using BUDS to compensate for a larger tire. They should at least call BRP to see if it can be done.

 

[bjt]

Two things. If you remove the wheel sensors, you should also disable the DPS. I think it was Evan that did this and said the steering was scary without the sensors hooked up and the DPS enabled because the Spyder thought you were always at 0 MPH and would give maximum steering assist all the time. That made it too touchy at high speeds. Also, if you wanted to ride with the larger tire all the time, I'm sure some smart (engineering type) person could figure out how to make a new "target wheel" for the rear sensors that had a different spacing to compensate for the larger tire size. I would think they would just have to calculate the ratio of the old tire vs. new tire and determine what new spacing the targets (metal projections) on the new target wheel would be by applying that ratio to the current target wheel. Of the two, disabling the DPS and removing the sensors would be the easiest but not having steering assist at all takes some getting used to and wouldn't be ideal for everyday riding.

 

[NancysToy]

had to be sure, I gained at least 5mph with a new rear tire so I was testing the idea, I think the red line in 4th would get there being taller, 5th is like overdrive in the wind or up a hill. here are some pics.

That makes sense. If it could have gotten you to the traps in a lower gear it would have been optimized. Guess I've been away from the track too long...or drove to many direct drive (high gear only) cars.

 

[QuadManiac]

Simple suggestion - if you're willing to do some permanant disfigurement - Since the wheel sensors are just sensing the teeth on what was previously called the 'target wheel', removing one or more of the teeth from both FRONT 'target wheels' will make the system see fewer counts per revolution - same thing you've caused at the rear end with a larger tire. I doubt that the computer will notice the 'step' change when one or more (not contiguous) are missing, I suspect it just counts the number of teeth and compares the counts from each wheel per unit time.

With a cursory look there appears to be about 60 teeth on the front wheel, give or take (Please count for yourself!!!). SO, if you increase the rear tire size by 7% (going from 14" to 15"), then removing 7% (or 4) of the front 'target wheel' teeth will get you close to matching wheel sensor counts between front and back. Since there is a fixed number of teeth, you will be limited in the step size that you can change - for instance, with my hypothetical 60 total teeth, you can only change in 1.666% steps. BUT, this should get you closer, and then with a bit of tire pressure changes you could get close to exact.

The only thing i'd recommend if you're going to try this - if you need to remove more than one projection, do it in a symmetric fashion, e.g., if four - 90 degrees apart, if five - 72 degrees apart, etc., just to prevent missed counts from being lumped too close together.

If you're willing to permanantly grind off a few teeth, I think this might be a viable solution. Eventually, after you've proven the process and have it dialed in, you can have a pair of custom 'target wheels' made (or combination of custom front and rear target wheels to get REAL close) with tooth number and spacing that will match any difference in tire size between front and rear.

Also, since the 'target wheels' are just flat metal and relatively easy to remove and attach, I can't expect that they'd cost TOO much from BRP, so you can always return to stock - OR have several different versions for several different tire combinations.

 

[Firefly]

Simple suggestion - if you're willing to do some permanant disfigurement - Since the wheel sensors are just sensing the teeth on what was previously called the 'target wheel', removing one or more of the teeth from both FRONT 'target wheels' will make the system see fewer counts per revolution - same thing you've caused at the rear end with a larger tire. I doubt that the computer will notice the 'step' change when one or more (not contiguous) are missing, I suspect it just counts the number of teeth and compares the counts from each wheel per unit time.

With a cursory look there appears to be about 60 teeth on the front wheel, give or take (Please count for yourself!!!). SO, if you increase the rear tire size by 7% (going from 14" to 15"), then removing 7% (or 4) of the front 'target wheel' teeth will get you close to matching wheel sensor counts between front and back. Since there is a fixed number of teeth, you will be limited in the step size that you can change - for instance, with my hypothetical 60 total teeth, you can only change in 1.666% steps. BUT, this should get you closer, and then with a bit of tire pressure changes you could get close to exact.

The only thing i'd recommend if you're going to try this - if you need to remove more than one projection, do it in a symmetric fashion, e.g., if four - 90 degrees apart, if six - 60 degrees apart, etc., just to prevent missed counts from being lumped too close together.

If you're willing to permanantly grind off a few teeth, I think this might be a viable solution. Eventually, after you've proven the process and have it dialed in, you can have a pair of custom 'target wheels' made (or combination of custom front and rear target wheels to get REAL close) with tooth number and spacing that will match any difference in tire size between front and rear.

Interesting idea.

This all seems like too much work for such little possible gains.

You want to really get more top end--- you're going to have to change the gearing.

 

[NancysToy]

Simple suggestion - if you're willing to do some permanant disfigurement - Since the wheel sensors are just sensing the teeth on what was previously called the 'target wheel', removing one or more of the teeth from both FRONT 'target wheels' will make the system see fewer counts per revolution - same thing you've caused at the rear end with a larger tire. I doubt that the computer will notice the 'step' change when one or more (not contiguous) are missing, I suspect it just counts the number of teeth and compares the counts from each wheel per unit time.

With a cursory look there appears to be about 60 teeth on the front wheel, give or take (Please count for yourself!!!). SO, if you increase the rear tire size by 7% (going from 14" to 15"), then removing 7% (or 4) of the front 'target wheel' teeth will get you close to matching wheel sensor counts between front and back. Since there is a fixed number of teeth, you will be limited in the step size that you can change - for instance, with my hypothetical 60 total teeth, you can only change in 1.666% steps. BUT, this should get you closer, and then with a bit of tire pressure changes you could get close to exact.

The only thing i'd recommend if you're going to try this - if you need to remove more than one projection, do it in a symmetric fashion, e.g., if four - 90 degrees apart, if five - 72 degrees apart, etc., just to prevent missed counts from being lumped too close together.

If you're willing to permanantly grind off a few teeth, I think this might be a viable solution. Eventually, after you've proven the process and have it dialed in, you can have a pair of custom 'target wheels' made (or combination of custom front and rear target wheels to get REAL close) with tooth number and spacing that will match any difference in tire size between front and rear.

Also, since the 'target wheels' are just flat metal and relatively easy to remove and attach, I can't expect that they'd cost TOO much from BRP, so you can always return to stock - OR have several different versions for several different tire combinations.

Depends on whether the sensor samples rate, or counts pulses. If it samples rate between pulses, this wouldn't work. If it counts the pulses, it would only work if the sampling period was fairly long, and an even amount of revolutions or fractions, depending on the number of targets removed. If you had four gaps, and it counted 1/3 a revolution, for instance, the count would be way off when two gaps got counted. I doubt they use the counting method, since it would make for a serious lag in the system. Bad effects on the ABS. Remember, The "D" in R&D also sometimes stands for "Dangerous". This is a "Test Pilot" level of experimentation, and rectifying it if it didn't work could also be expensive.