vectorsolid

What causes shake, chatter, hop?

93 hatch, ETD traction bar, 24.5-8.5x13 M&H slicks at 7 psi, obx LSD.

I enjoy a decent burnout. Don't even care if it's necessary, so let's not debate that. I want to know how to keep tire hop, chatter, shake, out of my burnouts to make life easier on my axles, tranny, etc. And help put on a better show for the crowd (and myself).

Car only does it during the burnouts. I can spin the tires at say 40mph over the actual car speed for 3-4 seconds during a pass with no incident at all. Car tracks straight, drives straight, burns out straight. I scaled the car to get the weight equal on the fronts and that helped a pile.

Longer burnouts, 4+ seconds. Starting in third, I let out the clutch, and jumps to about 105-111 and I ride the limiter until it starts to shake at about 2-3 seconds into the burnout and usually let off. "LATELY", I've decided to ride through some of the shake (because I like the look of a longer burnout) and finally blew a CV in the burnout box. I had another axle that was about to go, that I replaced about 10 runs earlier. So in the last 20 passes, 2 CV's used up. Both were my stupidity, I make no claims to the other.

What causes shake, chatter, hop? What can I look at to prevent or limit it?


Modified by vectorsolid at 12:57 AM 9/23/2008

slowman

iTrader: (3)

possibly a quality name brand suspension setup.

but i think you'd notice a bigger difference if you change the motor mounts.

vectorsolid

Coilovers are Tanabe Sustec Pro SS

All mounts are new. Engine movement is fairly low if at all.

Video of engine movement.
http://www.youtube.com/watch?v=3ejBDA__HYM



Modified by vectorsolid at 12:57 AM 9/23/2008

SPOOLINmatt

do you have any traction bars. I've never EVER had hopping on burnouts. What engine mounts do you have? 3 sec burnout is all that you need.

INCNTRL4

I did a 3rd gear burn out this weekend for the first time, prolly 5 - 7 seconds long. I have stock mounts, and do NOT have traction bars, and did not have any vibration issues. Also I have same size tires, and was run 9psi in them.
However I did not stay in the burn out box, it was a rolling out of the box, not sure if that would make a difference.

I think you might need some tighter suspension!

vectorsolid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SPOOLINmatt &raquo;</TD></TR><TR><TD CLASS="quote">do you have any traction bars. I've never EVER had hopping on burnouts. What engine mounts do you have? 3 sec burnout is all that you need. </TD></TR></TABLE>

I mentioned ETD traction bars, and that I don't really care if the burnout duration is "necessary" but that it's important to me to lay down some smoke, regardless of how it effects the pass in a positive or negative way based on time of burnout. I just want to get rid of the chatter

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by INCNTRL4 &raquo;</TD></TR><TR><TD CLASS="quote">I did a 3rd gear burn out this weekend for the first time, prolly 5 - 7 seconds long. I have stock mounts, and do NOT have traction bars, and did not have any vibration issues. Also I have same size tires, and was run 9psi in them.
However I did not stay in the burn out box, it was a rolling out of the box, not sure if that would make a difference.
I think you might need some tighter suspension!</TD></TR></TABLE>

9 psi is a fair amount of air. I'd be curious how it reacts at 6.75 - 7psi. I generally roll while doing a burnout as well. The difference being I want to keep them lit up, and smoking and roll across the line and have to back up to stage. Some places are cool about that, some are not. Know your track.

I'm starting to feel this is a geometry issue, and possibly related to the 6.75-7psi in the tires. Perhaps the chatter, which happens as the tire heats at say the 3 second mark, has something to do with the wrinkling and un-wrinkling of the tire as it's gaining traction during the heating process. They are spinning at about 110mph in 3rd.

Or, perhaps it's something to do with how much the tire grows at speed. the front of the car raises about an inch, due to tire height increase, during the burnout.

Or, there is cause effect thing going on when you ride the limiter and the engine pulses power to a wrinkled and un-wrinkling tire sidewall.

Or it's a geometry issue with the traction bar arm as it connects to the LCA. There must be a cause and effect relationship between one end being higher and lower than the other.

The only other thing that could be changed would be toe in or caster. And how they could effect chatter or hop. I could see toe-in having an effect, but I'm not so convinced on caster.

I think we can rule out, on this car.
shocks (unless there is a superior dampening adjustment that could be made, but the fastest cars have little or no movement)
ball joints
engine mounts

vectorsolid

Hmm, I was just thinking about something else it could be. On my EF chassis there is a secondary plate that adds mounting points to help stiffen the ETD traction bar to the chassis.

I wonder if that could have some effect. The one on my EF was a shitty fit, so I made my own bracket. It's shown here in this picture. Takes a pile of flex and leverage out of the equation. Although it would have to be moving a LOT to make the chatter necessary.

90dxhmt

iTrader: (1)

Buy some urethane control arm bushings or just get the whole kit for the car they are a bugger to install but much worth it

vectorsolid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 90dxhmt &raquo;</TD></TR><TR><TD CLASS="quote">Buy some urethane control arm bushings or just get the whole kit for the car they are a bugger to install but much worth it </TD></TR></TABLE>

Got 'em on the car now. I'm not sure they would have that effect anyway. Relative to a burnout, the inner mount on the LCA should have low effect, the radius arm should be taking 80-90% of the force and it's mounted with heims.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rota92 &raquo;</TD></TR><TR><TD CLASS="quote">You're rolling through the water top fuel style and carrying the burnout on the dry stuff?

That should be your problem right there lol I ran 4 psi in my tires, stopped, revved up, let the clutch out nicely, burned some tire and let it yank me out of the water and then staged.

If you're trying to make something happen, that isn't supposed to the chassis could be getting unsettled while you're just beating on it lol

Try a nice 'in place' burnout and see how that feels.</TD></TR></TABLE>

Roll through and stop. Start the burnout, start bouncing the limiter and ease up on the e-brake. I make sure the box is good and wet (resisting the easy humor on that), I wait until the very last second to roll through, stop and hit it.

I can't recall if it does it or not if I just try and stay planted and not roll. I think that it still chatters a bit. I've got about 25 passes on the car now, so I'm still sorting stuff, but getting closer.

4psi?!? Did the box guy point at your tires and try to toss ya? ...lol... I've got wrinkles overlapping wrinkles on 5psi, was afraid to try it.

It's possible that "I" may not be compatible with the chassis. You're right, it could be me wanting the car to do something it doesn't want to do. But I'm gonna try and make it work. It seems other dudes get their cars to do the bigger 5-6 second burnouts. I know it's not completely necessary. I want to make it happen anyway. I enjoy that part of the pass.

I called ETD. I was kind of surprised at how little they know about what the bar does. Nose high, nose low, level, not much difference according to them, nor could they really say what those adjustments would do. Seriously?

So, uh... It's a traction bar right? what do the adjustments do? "not much". So nose high gets me what, relative to traction "you'd need to test that for your application"....

How can you sell an adjustable traction bar and not know what the adjustments do?


Modified by vectorsolid at 2:48 PM 9/23/2008

vectorsolid

Looks like this, ignore the rest of the pass. Hit it, max it, start rolling. The only reason I let off was because of the chattering.
http://www.youtube.com/watch?v=_DsKCgLMfOA

vectorsolid

Modified by vectorsolid at 3:26 PM 9/23/2008

1992Si

I sent him so burnout's in a PM.

vectorsolid

Got the vids. Sweet.

vectorsolid

Anybody know what adjusting the radius arm nose high, level, or nose low actually gets you?

vectorsolid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rota92 &raquo;</TD></TR><TR><TD CLASS="quote">Preload, and tow I believe?</TD></TR></TABLE>

I dunno. The majority of toe comes from the steering rods, and you can change castor with the radius rods. If that's what you meant.

Honda Bull

I've gotten shake in some of my burnouts lately, on 22" slicks aired to 6 psi cold. I do them in 2nd. It never had that issue when I was all motor and had them aired to 10-12 psi. And of three tracks I've been to, I've had shake at two but not the one. I also had no issues burning out on drag radials at another track. Not sure what to make of it, but tire shake like that feels awful. lol

4piston

Tire shake is usually from a lack of power causing too much traction. Try to keep your wheel speed up.

CompressionFed

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4piston &raquo;</TD></TR><TR><TD CLASS="quote">Tire shake is usually from a lack of power causing too much traction. Try to keep your wheel speed up.</TD></TR></TABLE>

Right. I was about to say, usually tire shake is from not putting enough power to the ground.

vectorsolid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CompressionFed &raquo;</TD></TR><TR><TD CLASS="quote">

Right. I was about to say, usually tire shake is from not putting enough power to the ground. </TD></TR></TABLE>

Here's a burnout and (crappy BOG pass), to analyze. It's chattering when I let off, you can't see or here it on the video. This is 3rd gear, bumping on 9100rpm limiter.
http://www.youtube.com/watch?v=_DsKCgLMfOA
and another.
http://www.youtube.com/watch?v=ZObUrg2GafQ

Is it possible that bumping the limiter makes it worse? As in, the power's good, then cuts, then good, then cuts. Perhaps instead, get 'em spinning and modulate the throttle just below the limiter? I have no idea. Just throwing out a thought.

For what it's worth, I'm just doing a fuel cut, not fuel and ignition.



Modified by vectorsolid at 3:03 PM 9/24/2008

1992Si

I seem to recall after I put rota's traction bar on I shorten the hiem joints until they felt right, not a lot of stress/torque to shorten them, may be just a turn or turn and a 1/2 in the shorter direction.

4piston

You don't need to beat it off the limiter forever to get heat in the tires. If you can get your wheel speed up you don't need a long burnout. Are you doing these in 3rd gear?

tepid1

I think there is a bit more to it than air pressure, alignments, and a traction bar....

Look at the wheels you are using. Last time I spun up a Lenso in the balancer all by itself just to see where it was at, it was all over the place. The exact reason why I switched to Weld wheels....

Resonation comes to mind as well. If you vary your speed instead of keeping a constant speed then the tire doesn't have time to resonate or vibrate. Maybe I'm thinking too much into this....

What slicks are you using? Do the lot numbers match? Remember that lot number are very important when using slicks. There are slight difference between lots.

What axles are you using? Stock axles have a harmonic rubber piece to prevent resonation and vibration in the driveline. Many aftermarket axles, even the best ones, don't have this, but are very well balanced. Your cheaper axles will most likely be all over the place as well.

Ever check your front wheel bearings? What condition are they in? Any play? Put the car on a lift and try to rock the wheel side to side and top to bottom. If there is any play at all.... it's f'ed up.

Hope this info helps mang.

jgf

The quickest way is to sell your Honda, get a domestic 60's or 70's muscle car. You'll have rear wheel drive for better burn outs, go faster, have a great looking car and increase your "cool" factor 100 fold. I'm not kidding, I switched from a Honda a couple of years ago and am having a lot more fun. Another thing is sport compact racing is dieing, less races, lower car counts. Time to get out and come over to the "cool" side and have some serious fun. Hope this helps, good luck.

vectorsolid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4piston &raquo;</TD></TR><TR><TD CLASS="quote">You don't need to beat it off the limiter forever to get heat in the tires. If you can get your wheel speed up you don't need a long burnout. Are you doing these in 3rd gear?</TD></TR></TABLE>

Yea, 3rd gear. Having really analyzed it hard this week... sad as it may be, at least for me, it would appear that the long burnout isn't really helping the pass... But I LIKE IT ANYWAY. but I am starting to see the light. It's cool, but not necessary... dang it.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tepid1 &raquo;</TD></TR><TR><TD CLASS="quote">I think there is a bit more to it than air pressure, alignments, and a traction bar....

Look at the wheels you are using. Last time I spun up a Lenso in the balancer all by itself just to see where it was at, it was all over the place. The exact reason why I switched to Weld wheels....

Resonation comes to mind as well. If you vary your speed instead of keeping a constant speed then the tire doesn't have time to resonate or vibrate. Maybe I'm thinking too much into this....

What slicks are you using? Do the lot numbers match? Remember that lot number are very important when using slicks. There are slight difference between lots.

What axles are you using? Stock axles have a harmonic rubber piece to prevent resonation and vibration in the driveline. Many aftermarket axles, even the best ones, don't have this, but are very well balanced. Your cheaper axles will most likely be all over the place as well.

Ever check your front wheel bearings? What condition are they in? Any play? Put the car on a lift and try to rock the wheel side to side and top to bottom. If there is any play at all.... it's f'ed up.

Hope this info helps mang.</TD></TR></TABLE>

Appreciate it. Some good things to consider. I checked the slicks are identical so that's handled. I had the lenso's balanced, after I screwed the tire to the rim, so it's as good as that's gonna get. There might be something to that harmonic thing. Wheel bearings were new when I did the studs.

could be the axles. Never really thought about the ones with the rubber donut offering any kind of difference relative to our application.

I think I'm gonna do the DSS 5.9's on it this winter. Just eliminate that from the equation. And maybe go to the 25-8.7-13 M&H's from the 24.5-8.5-13.

Appreciate the thoughts. I like to look at less common solutions and ideas.

A train

cause you have a rear wheel drive it increase your cool factor 100% come on when the domestic cars see what we do in our 4 bangers they think thats pretty cool. bann jgf please nothing but negitive things to say! bring that rear wheel drive and let us show you how cool it looks to see you in our rear view mirrors! ron weems found that out!