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Bump Steer Mod
Posted by
Dezsled
on 03 Oct, 2012 19:15
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After reading the lt250 camber mod w/ the bump steer mod mentioned, there was a mod for the lt500 wasn't there?
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#1 Reply
Posted by
Nopick
on 03 Oct, 2012 19:42
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The 500 bump steer mod is to install a 0.25 inch shim on the lower ball joint, same as the 250. Also move the inner tie rod end up 0.2 inches with washers between the tie rod end and the steering stem. Then reset the toe in to a quarter inch. That's what I did based on information from QRHQ. Seems good bit then I didn't ride the Zilla without the mod.
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#2 Reply
Posted by
Rogue1970
on 06 Nov, 2012 12:18
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There is a horrible amount of bump steer with the stock Zilla. I've heard of flipping the outside tie rod ball joints, changing the mounting arms for the ball joints, etc...
Well I thought I would throw up some measurements I made this summer of my front end. I have the Camber mod on my 500, but I wanted to know where to set my toe at, so I started checking to see just how bad it is.
Here are some of my measurements: 12 3/4" travel from full droop to fully compressed (no shocks). Initial measurements.... Measured from center to center of ribbed tire.
Quad only weight; Toe In set at 1/8 inch.
42 1/8" Front of tire
42 1/4" Rear of tire
Full Droop (no shocks)
38 3/8" Front of tire
41 1/8" Rear of tire
2 3/4" Toe In
Level A-Arms (no shocks)
44 5/16" Front of tire
43 3/16" Rear of tire
1 1/8" Toe Out
Full Compression (no shocks)
40 1/2" Front of tire
42 3/4" Rear of tire
2 1/4" To In
3 7/8" toe range!
When you cycle the suspension with no shocks the Toe travel looks like this:
/ \ Toe-in full drooped suspension
| | Toe 0 moving towards level a-arms
\ / Toe-out level a-arms
| | Toe 0 moving towards full compression
/ \ Toe-in fully compressed a-arms
So, I wanted to cut down on the amount of toe out, so I set my toe in to 5/8 (.625)" under quad weight this summer.
Anybody have a true fix for the bump steer? I would like the Zilla front end to be like my Long Travel KFX450 Houser setup that is on my wife's bike. It has almost no bump steer.
I played with flipping the ball joints, adding washers above and below the linkage arm, but never found a good sweet spot. Different stem mounting points? Different spindle mounts?
I should look at this again in the next few days again to see if I can reduce the toe out some more.
Any tips guys?
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I've found this way to work best on my Zilla. Swapping the steering arm to the bottom of the spindle mount.
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#4 Reply
Posted by
Q2W
on 06 Nov, 2012 13:31
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I saw a video where Q was making a new piece that went between the tie rod and the spindle that was supposed to eliminate bump steer.
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#5 Reply
Posted by
Nopick
on 06 Nov, 2012 13:34
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I talked to Q about that. He wants to make them out of steel to reduce chances of them bending on a hard hit. I think he said prototype units were AL.
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#6 Reply
Posted by
Q2W
on 06 Nov, 2012 13:35
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yea, i remember them being billet.
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#7 Reply
Posted by
QuadDave
on 06 Nov, 2012 14:28
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Rogue,
On my 250, I left my shocks on when I did this. Your obviously going to get more extreme measurements with no shocks as it will allow the suspension to cycle further than normal.
I set the toe to zero at full suspension droop (shock fully extended)
then I measured the toe at 1/2 suspension compression and wrote it down
then I measured the toe at full suspension compression
From what I was told, the minimum toe-in should be 1/16" at the "Worst" part of the curve.
This is under the assumption you have "toe-out" bump steer in the center as most LT's do and from your illustration, it looks like you do.
That measuring process is what I used to check my progress when I was adjusting the height of the ends of my tie rods until I limited the amount of toe-in/toe-out when I cycled the suspension through it's range.
The key is to take your time.
Once I had it down to the minimal amount, I realigned to a 1/4" toe-in.
By the way, it still has some bump steer, but not nearly as bad as it was and with the camber mod, it has helped a lot.
Hope this helps.
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#8 Reply
Posted by
Rogue1970
on 06 Nov, 2012 21:36
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I've found this way to work best on my Zilla. Swapping the steering arm to the bottom of the spindle mount.
I tried that, but will try it again and take some more measurements to see if I can reduce the bump steer.
Rogue,
On my 250, I left my shocks on when I did this. Your obviously going to get more extreme measurements with no shocks as it will allow the suspension to cycle further than normal......
Yes, I agree that I should take my measurements with the shocks on - no springs to get true measurements....
Thanks for the suggestions guys.
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#9 Reply
Posted by
MD2smoker
on 08 Nov, 2012 05:55
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So, does this mean that the .20 spacer at the inner tie rod ends is not enough to reduce bump steer?
Its my understanding that bump steer is directly related the the position of the ball joints, tie rod ends, and a arm pivot points being on the same plane with each other. As the suspension compresses , the arms do not follow the same arc as the tie rods, thus allowing the spindle to steer in and out.
Has anybody taken bump steer measurements with the z400 spindles ? Is be curious to see if it improves anything. I'm trying to figure out if the spacer, camber mod, and flipping the outer tie rod mount add up to a large reduction in bump steer. or of only the tie rod spacer and camber mod are necessary.
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#10 Reply
Posted by
Nopick
on 08 Nov, 2012 06:30
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The 500 we rebuilt last winter has the 0.2 inch ball joint spacer camber mod and the 0.1 inch bump steer mod at the tie rod / steering stem connection. I posted previously that the tie rod was spaced by 0.2 inches, it is actually 0.1. Anyway, my Dad purchased a 500 without the camber and bump steer mods and I rode both machines last weekend on the same rough sand. I didn't notice an appreciable difference in bump steer. The turning and handling of the machines were very different, however, with the camber modded bike making much quicker and more predictable turns. (I especially noticed this trying to follow Q2W through the trails on the un-modded machine... Lots of push when turning.)
I do not remember seeing anything on QRHQ about flipping the tie rod / spindle mount on the 500, only on the 250. Does that help out on the 500 as well.
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#11 Reply
Posted by
Rogue1970
on 08 Nov, 2012 23:07
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Camber mod will not impact the bump steer at all if any. The Camber mod can be seen when you are looking at the front of you quad. See the following for a diagram of Camber - Positive, Negative, and Neutral:
Stock Quadzilla's have Positive Camber which is not desireable. This mod makes the Zilla have 1 or 2 degrees of negative Camber.
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#12 Reply
Posted by
MD2smoker
on 09 Nov, 2012 05:09
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Yup, im familiar with. Camber and caster adjustments and how they affect the handling. Ive done a lot of testing with my yfz aftermarket front end to see what the adjustments do.
What im wondering about is the z400 spindles... Has anybody measured to.see if they improve bump steer? I had my buddies kfx 400 at my house for a while, I should have tried some measurements to see what differences it would make, if any, on the the zilla.
Thanks for the info on your front end measurements btw Rougue, once I get some spacers in hand, ill do the same with my trail zilla with shocks on, springs removed to see what I come up with.Its 33 degrees here in md right now, need to do something. Im kinda a nerd with a tape measure and an angle gauge.. Lol
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#13 Reply
Posted by
Rogue1970
on 09 Nov, 2012 08:00
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Nice MD2smoker. Looking forward to any light you can shed on the LT250/500 front end. I would also like to know the numbers on the z400 spindles.
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#14 Reply
Posted by
Dezsled
on 09 Nov, 2012 08:42
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I'm interested in the z400 spindle swap...using aftermarket +2+1 a arms & 16.5" shocks.
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#15 Reply
Posted by
MD2smoker
on 09 Nov, 2012 21:48
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So was just visually looking at my zilla front end vs. my yfz. the zilla tie rods are at a lower angle to the a arms as opposed to the yfz. The yfz is almost perfect as far as a arm / tie rods being at the same angle.
The zilla has a signifigant drop in the placement of the inner tie rod ends at the steering stem location. I have been nagging my buddy to get his kfx out of my shed for months now and now I want it back! LOL
Im pulling a lower ball joint bolt this weekend to take to a local hardware supply house to have .375 spacers made/ordered and a longer bolt as Iceracer had suggested to get -2 deg. camber. I usually run -4 deg. on my yfz. Ill put the shims in under the front inner tie rod ends and see what ive got.
I prefer more neg camber for reaction and steering precision, but run a cross country style caster angle for higher speed stability. Just seems to fit my riding style.
Im gonna keep playing with some spacer combos this winter to see what actually works and what dosent, but i have to say that the frame and a arm geo on the zilla is not the best starting point. Still better than the 250 tho.
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I'm interested in the z400 spindle swap...using aftermarket +2+1 a arms & 16.5" shocks.
Dale ran set of Z400 spindles on his set up like this and he said that there was more travel with the OEM zilla spindles ovr the z400s.
If he'd care to chime in about the bum steer of the z400s VS the stock ones on the +2/+1 arms.
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#17 Reply
Posted by
Dezsled
on 15 Nov, 2012 09:03
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Well that's a definite negative for the z400 spindle swap.... I was looking to use my extra Honda rims
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#18 Reply
Posted by
Q2W
on 15 Nov, 2012 09:29
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Even Mike, 500fanatic, said that if he had it to do over he'd just do a long travel setup in lieu of the YFZ clip he put on his hybrid.
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#19 Reply
Posted by
Nopick
on 15 Nov, 2012 09:46
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Even Mike, 500fanatic, said that if he had it to do over he'd just do a long travel setup in lieu of the YFZ clip he put on his hybrid.
He said the same thing to me about his hybrid but the reasoning was that the Zilla was just laid out better for a taller guy.
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#20 Reply
Posted by
Rogue1970
on 15 Nov, 2012 12:08
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I came from a long travel KFX450, am 5'8" and 190. I love the Zilla too. So much more stable for my style of riding (fast sand dune carving).... and all of this on stock a-arms and a stock swinger.
Once I can get the front end setup the way I want, it should be the perfect quad. Get these jetted right and they will start with one kick starts always!
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#21 Reply
Posted by
MD2smoker
on 29 Jan, 2013 05:51
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Yesterday I put my .375 spacers on the lower ball joints and shimmed the inner tie rod ends. The combo of spacers and washers I used came up to about .22 in. for the tie rod ends.
My question is about the nut on the bottom of the tie rod end. There isnt enough threads left for a cotter pin. Even if I did only.2, there wouldent be enough room. What have you guys done? Lock washers and loc tite?
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#22 Reply
Posted by
Q2W
on 29 Jan, 2013 08:57
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you sure they are stock? mine fit with plenty of room. Hell maybe mine aren't stock. lol.
I think the ultimate fix for the bump steer is to get the tie rods as flat as possible? The new 450's tie rods are mostly flat while the zilla's has a steep angle. Maybe modding the piece that connects the tie rod to the spindles would work better.
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#23 Reply
Posted by
JayTater
on 29 Jan, 2013 09:53
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The biggest part is to get the tie rods parallel with at least your lower a arms. That will get rid of some of the toe in issues. The width of the frame is going to make it nearly impossible to eliminate all of toe in problems. Because the arms and tie rods don't travel in the same arc, the tie rods will push the toe out when the suspension is compressed. It's why almost all of the manufacturers are building their quads with such a narrow frame now. I'm actually working on a couple things right now to try and compensate.
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#24 Reply
Posted by
Q2W
on 29 Jan, 2013 10:05
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Right, i've been thinking about trying to narrow the front part of the frame. Mimic the 450's some what.
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