[Marko]

So went out for a ride today in about a foot or so of snow and WOW the wheel hop! In four wheel drive i couldn't get the machine to climb the slightest grade. It was less in the fresh powder but was still there and if you started to spin too much the bike felt like it might come apart. It would do it in 2 wheel drive and 4. It was less noticeable in two but still there.

Has anyone had this before? I presume riding in the sand has to be same sort of thing as a packed snow trail. I've had it out in the snow prior, on the lake and river, no problems. Down the ditch in fresh and packed but it seemed as soon as it got into the deep stuff the machine was useless, had to shut it down before it broke something.

Is it a suspension thing? (running plush ELKA shocks) Tire issue? ( running OEM tires) Something with the suspension geometry? ( same idea as the bucking)

Thanks in advance for the help peeps.

 

[TOGR]

Something is probably out of balance, bent or starting to come apart. Start by checking tires, wheels, axles and driveshafts.

 

[hondatalonr]

I doubt anything is bent. My R also did this in the sand, The stiff springs that Honda puts on seem to cause this. Don't have any experience with snow.

 

[Marko]

I doubt anything is bent. My R also did this in the sand, The stiff springs that Honda puts on seem to cause this. Don't have any experience with snow.

Nothing is bent, broke or other.

I put the OEM shocks back on, it didn't seem to make any huge difference maybe a little better. Aired the tires up to 20psi rear and 17psi in the front, this made it way worse. Went down to 7psi rear 5 psi front, this seemed to have helped the most. Was running 10psi rear and 7psi in the front.

Going to try removing the sway bar next to see if that helps. Would like to try a different set of tires but that turns into an expensive experiment. might try this lower tire pressure with the Elka's back on the machine.

 

[PaulF]

They all do it, mainly in sand and snow. It gradually subsides as the suspension settles/softens and you get used to the machine and how to drive it under certain conditions. Mine went almost completely away after having Weller Racing tune my shocks. It has only done it to me a couple times in the sand when I had my dirt tires on in the past couple years. It never does it with my paddles on.

 

[Marko]

They all do it, mainly in sand and snow. It gradually subsides as the suspension settles/softens and you get used to the machine and how to drive it under certain conditions. Mine went almost completely away after having Weller Racing tune my shocks. It has only done it to me a couple times in the sand when I had my dirt tires on in the past couple years. It never does it with my paddles on.



Thanks everyone for the help. Kinda figured it was a universal problem. Going to try putting the Elka's back on and see what it does with the tires aired down, mess with the rebound and compression, try pulling the sway bar. Sounds like tires play a large role so if anyone playing in the snow has a recommendation please let me know.

Again, thanks everyone for the help.

 

[nm6r]

Is it a suspension thing? (running plush ELKA shocks) Tire issue? ( running OEM tires) Something with the suspension geometry? ( same idea as the bucking)

I assure you the rear end bucking has nothing to do with the suspension geometry.

 

[TOGR]

I hear the "rear end geometry" issue over and over. I think it started with Shock Therapy in their dissing of the Talon to get business, but they do not explain what they are talking about and then it just gets repeated like it is gospel. Can someone please explain what is being referred to, if there is really a "geometry issue."

 

[PaulF]

First off, this is only referring to Bucking, not rough ride, wheel hop, etc.

ST does in fact explain it in detail on the X and it has to do with the intersection between the tire ground contact, trailing arm front mount point and Center of Gravity. The center of gravity is forward of the the intersection and causes the nose to dive and therefore the bucking. Longer control arms (like a RZR or Can AM) puts the intersection in front of the COG and reduces bucking (any car can buck, the suspension determines how much under what condition). Only fix for the X is to install longer control arms and no one (as of today) has engineered that as far as I know.

ST does not explain it on the R. The R's 4 link suspension is a lot more complex and I have measured the center of gravity and plotted out the geometry and I guarantee you that rear suspension geometry on the R has a lot to do with the bucking. The Anti-Squat on the R is over 100% (my Talon is 111%) and while that it good for a rock crawler/hill climber, it is horrid for a desert racer. The only way to fix it is to change the rear geometry. Shock tuning can help but will never eliminate it. Typical Anti-Squat is like this...

• Anti-squat between 140% and 180% works well for drag racing on smooth pavement with heavy rebound valving.
• Anti-squat between 110% and 150% works well for hardcore technical rock crawling and some styles of rock bouncing.
• Anti-squat between 100% and 130% works well for mud drag racing and some hill-n-hole racing.
• 100% Anti-squat is a good universal default starting point for a multi-purpose vehicle.
• Anti-squat between 80% and 120% works well for almost every off-road application (excluding desert racing).
• Anti-squat between 80% and 120% works well for almost every street and track application (excluding drag racing).
• Anti-squat between 70% and 100% works well for rock crawling and trail running.
• Anti-squat between 20% and 80% works well for open road racing and rally racing.
• Anti-squat between 10% and 50% works well for high speed desert racing.

The reason that both the X and R benefit from adding weight as far back as possible is because it doesn't change the geometry, it does move the COG back and down and changes the intersection point on the X and the Anti-Squat on the R.

 

[PaulF]

Here is how the R works (courtesy of crawlpedia.com). The bolded text is what causes the bucking...

Rear: Anti-Squat Over 100%

Suspension systems with anti-squat values over 100% will cause the rear end of the vehicle to raise up and unload the rear suspension under acceleration or when the rear tires contact an obstacle at speed. These characteristics are desired for drag racing and heavy acceleration applications because the forces that push the rear end up also push the rear tires down for more traction. At speed, however, when the rear tires impact an object, that immediate increase in traction will cause the power applied to the rear axle to raise the chassis up at the same time as the suspension is trying to compress and absorb the impact.

 

[TOGR]

Very interesting. I guess it boils down to the Talon being a compromise, which is a common theme for Honda. Honda came out with the XR400 before coming out with the CRF450. Will Honda decide to make a CRF450-like SXS to compete with the Can Am and Speed units in desert racing, probably not. So instead we have a compromise that is rock solid reliable and does a very good job at rock crawling, mudding, hill climbing, trails, family fun and even fast desert (been in Baja now 2 months but do have extra weight on the rear), but was not developed exclusively for one of those, and should not be raced without significant modification.

Then the "geometry" issue is that the trailing arm is not longer/mounted more forward to be past the COG. Thank you for explaining this, as well as why adding weight to the rear of the thing indeed helps the situation.

 

[PaulF]

Very interesting. I guess it boils down to the Talon being a compromise, which is a common theme for Honda. Honda came out with the XR400 before coming out with the CRF450. Will Honda decide to make a CRF450-like SXS to compete with the Can Am and Speed units in desert racing, probably not. So instead we have a compromise that is rock solid reliable and does a very good job at rock crawling, mudding, hill climbing, trails, family fun and even fast desert (been in Baja now 2 months but do have extra weight on the rear), but was not developed exclusively for one of those, and should not be raced without significant modification.

Then the "geometry" issue is that the trailing arm is not longer/mounted more forward to be past the COG. Thank you for explaining this, as well as why adding weight to the rear of the thing indeed helps the situation.

You are correct. You cannot have a monster rock crawler and a whoop killer in the same machine, the characteristics that make it good at one make it bad at the other. Honda had to choose one and it will not suite all users. It is the reason Talons will "power" over an obstacle when a RZR/X3 would flip backwards in the same situation. Perfect example the vid below. It shows exactly what Anti-Squat over 100% does, it pushes the front end down when you are in trouble and nail the throttle (when in doubt, power out).

You will notice 2 distinct things about the Baha Talon and why they buck a lot less than a stock unit.

1. It is a 4 seater chassis with the drivers moved back a little and a lot of weight on the rear. This helps with the geometry/COG relationship.
2. They have limit straps on the rear suspension. This limits the trailing arm travel and reduces the suspension "unloading" that exacerbates the bucking.

I'm sure they did a lot more but you can't see it like the 2 obvious items above.

This vid shows exactly what 111% Anti Squat does...

 

[TOGR]

So as I am digesting this information, I have a couple observations.

I just watched the Dakar Stage 4 highlights and two of the race cars bucked and endo'd. Also if you Youtube "off-road crashes" or "Baja race crashes" a lot of those are from bucking/endo's. It hits me that every front engine Trophy Truck as well as every motorcycle is going to have the same condition, with the trailing arm/swing arm pivot being rearward of the COG. So Trophy Trucks and motorcycles handle this condition via suspension, which greatly helps, but does not necessarily eliminate it altogether.

I think I am going to Youtube "SXS crashes" and see if endo's are common with Can Am's, etc., even with the better geometry. Out of curiosity, what SXS's actually have their trailing arm pivot point forward of their COG, if anyone knows?

 

[PaulF]

So as I am digesting this information, I have a couple observations.

I just watched the Dakar Stage 4 highlights and two of the race cars bucked and endo'd. Also if you Youtube "off-road crashes" or "Baja race crashes" a lot of those are from bucking/endo's. It hits me that every front engine Trophy Truck as well as every motorcycle is going to have the same condition, with the trailing arm/swing arm pivot being rearward of the COG. So Trophy Trucks and motorcycles handle this condition via suspension, which greatly helps, but does not necessarily eliminate it altogether.

I think I am going to Youtube "SXS crashes" and see if endo's are common with Can Am's, etc., even with the better geometry. Out of curiosity, what SXS's actually have their trailing arm pivot point forward of their COG, if anyone knows?

All these buck/no-buck suspension scenarios are based on acceleration. The geometry forces are all opposite under deceleration so if you decelerate at the wrong time over a bump, ANY vehicle will nose over.

Most of the RZR/X3 nose dives are because the driver let off the gas at the wrong time. On the opposite end of the spectrum, here is a Talon jumping 3 times and the nose is up (almost a wheelee situation). This is atypical for a Talon and has everything to do with jump selection and staying in the throttle...

 

[TOGR]

Yeah, good point--driver input has a lot to do with it!

 

[dburt]

Take a Jeep, an FJ Cruiser or other 4x4 with locking axles in snow or sand and you can get the same hopping and bucking. Even with very low throttle input it can happen. Tire tread seems to make a little difference, tire pressure some difference, but it will still happen.