Posted By: Tig
SloMo Launch vid - 09/13/10 09:31 PM
Here's a vid from the last meeting.
http://www.youtube.com/watch?v=91dmTS-UvDc
http://www.youtube.com/watch?v=91dmTS-UvDc
SloMo Launch vid
Posted By: Tig
Re: SloMo Launch vid - 09/13/10 10:00 PM
Here's another one.
http://www.youtube.com/watch?v=4-w-tGU0Nks
Any tips on how to get rid of the wheel wobble
Cheers.
http://www.youtube.com/watch?v=4-w-tGU0Nks
Any tips on how to get rid of the wheel wobble
Cheers.
Posted By: dragram440
Re: SloMo Launch vid - 09/13/10 10:14 PM
I looks like it launches really awsome!!! The wheel wobble is definatley scary. Is that a whole hood on there or did you put the scoop on? I am looking for something taller then a stock one to clear my setup.
Posted By: Randy514
Re: SloMo Launch vid - 09/13/10 10:20 PM
Bump-steer usually attributed to stock suspension geometry woes. Our car does it but not as severe.. or maybe it does and I haven't looked at a slow motion video. I know its noticeable to the naked eye.
As the suspension drops on lift the geometry of the suspension gets out of wack with the un-equal length control arms and throws all the alignment angles out of wack. I think the common cure is aftermarket suspension and rack and pinion steering
Looking at the video it looks like your toe and camber are WAY out at the end of the second video Maybe have someone familiar with aligning race-cars set up the angles with the appropriate lift (in the front end at speed) Couldnt hurt Randy
As the suspension drops on lift the geometry of the suspension gets out of wack with the un-equal length control arms and throws all the alignment angles out of wack. I think the common cure is aftermarket suspension and rack and pinion steering
Looking at the video it looks like your toe and camber are WAY out at the end of the second video Maybe have someone familiar with aligning race-cars set up the angles with the appropriate lift (in the front end at speed) Couldnt hurt Randy
Posted By: sshemi
Re: SloMo Launch vid - 09/13/10 10:22 PM
Some more toe in maybe?
Looks like you could go a little stiffer on rear shock extension..or slow the front end rise down a bit.
But those launches look really cool, exept for the front wheel wobble.
Posted By: cheapstreetdustr
Re: SloMo Launch vid - 09/13/10 10:26 PM
actually moving the tierod end can fix this..
and poly bushings in the LCA's and strut rods.
that is alot of wobble.
id swear the lca is flexing...lol....
i might suggest trying a tad more air psi in the rear tires. see if the 60ft drops...?
cheapst
and poly bushings in the LCA's and strut rods.
that is alot of wobble.
id swear the lca is flexing...lol....
i might suggest trying a tad more air psi in the rear tires. see if the 60ft drops...?
cheapst
Posted By: mafo
Re: SloMo Launch vid - 09/13/10 10:37 PM
for me it helped to limit front end travel
casio exilim camera?
casio exilim camera?
Posted By: Tig
Re: SloMo Launch vid - 09/13/10 10:49 PM
Thanks for the reply's
The Hood is a old MAS piece from years ago, the scoop was modified to make it 3 inches taller.
Car has poly LCA bushes fitted, the strut bars are dynamic ones from CAP as are the Upper control arms.
I set the car up with a camber and castor gauge, after about 5 hours we got 5 degrees of castor zero camber and zero toe at + 1 inch, Tie rod ends were heated and moved up to level the tie bars with the LCA but thats not to say to say stuff hasn't moved since.
I've seen the wheels move on a normal speed camera it doesn't look that much, and the steering wheel wobbles briefly on touchdown. After seeing these vids I'll be checking stuff out pretty soon.
We were running a new brand of tyre, they seemed to have a stiffer sidewall than what we usually used. We were upping the air 1/4 lb per pass till we hit the sweet spot. The vids where from earlier in the day. Ended up with 12.5 psi but I think they could probably go more.
Rear shocks are on max ext damping (9 ways) I agree that slowing the front rise will help. Looking to upgrade the front shocks over the close season.
Sorry I've got no idea what camera the guy was using, makes for an exceptional tuning tool though.
Thanks again
The Hood is a old MAS piece from years ago, the scoop was modified to make it 3 inches taller.
Car has poly LCA bushes fitted, the strut bars are dynamic ones from CAP as are the Upper control arms.
I set the car up with a camber and castor gauge, after about 5 hours we got 5 degrees of castor zero camber and zero toe at + 1 inch, Tie rod ends were heated and moved up to level the tie bars with the LCA but thats not to say to say stuff hasn't moved since.
I've seen the wheels move on a normal speed camera it doesn't look that much, and the steering wheel wobbles briefly on touchdown. After seeing these vids I'll be checking stuff out pretty soon.
We were running a new brand of tyre, they seemed to have a stiffer sidewall than what we usually used. We were upping the air 1/4 lb per pass till we hit the sweet spot. The vids where from earlier in the day. Ended up with 12.5 psi but I think they could probably go more.
Rear shocks are on max ext damping (9 ways) I agree that slowing the front rise will help. Looking to upgrade the front shocks over the close season.
Sorry I've got no idea what camera the guy was using, makes for an exceptional tuning tool though.
Thanks again
Posted By: Big Squeeze
Re: SloMo Launch vid - 09/13/10 11:33 PM
Quote:
Here's a vid from the last meeting.
http://www.youtube.com/watch?v=91dmTS-UvDc
Did you guys see how the rear of the body goes up and down a few times while the front tires are in the air???
Posted By: Irun5snd8th
Re: SloMo Launch vid - 09/13/10 11:42 PM
Definitely saw that. Looks like it could use a bit stiffer compression in the shocks. Amazing video! What kind of camera/ video editing did that?
Posted By: Bigcube
Re: SloMo Launch vid - 09/13/10 11:52 PM
You could see it slam the tire and bounce it like a basketball.. More air? Awesom vids! 
Posted By: rowin4
Re: SloMo Launch vid - 09/13/10 11:54 PM
First thing I would check is the idler arm to see if the bushing is shot. 
Interesting video, really can learn allot with that slow motion camera . 
Interesting video, really can learn allot with that slow motion camera .
Posted By: Devilbrad
Re: SloMo Launch vid - 09/13/10 11:59 PM
Quote:
First thing I would check is the idler arm to see if the bushing is shot.
If you watch the second vid, you can see both front tires move in same direction at same time. Something is definitly worn in the steering if he isn't feeling much in the wheel.
Posted By: sixpackgut
Re: SloMo Launch vid - 09/14/10 02:12 AM
Quote:Quote:
First thing I would check is the idler arm to see if the bushing is shot.
If you watch the second vid, you can see both front tires move in same direction at same time. Something is definitly worn in the steering if he isn't feeling much in the wheel.
i seen that too. wonder if a very sloppy gear box could cause that. both videos are awesome. Tig, your car is awesome
Posted By: Cab_Burge
Re: SloMo Launch vid - 09/14/10 03:47 AM
Tig, your car is doing what the SS/AA car do, maybe Jared or lordan or one of Holtons will chime in on what they do to limit that wobble. I agree with slowing down the amount of rise on the wheelie and the resulting collision with the ground making things bend and wear 
I'm a firm beliver in getting both front tires off of the ground the least amount possible,no big wheelies for me 
BTW, your car is leaving very well, stiffen up and or slow down the suspension extensions and the car will probally go quicker and faster What size, brand and compuond are the new tires? Inquiring minds want to try them 
I'm a firm beliver in getting both front tires off of the ground the least amount possible,no big wheelies for me BTW, your car is leaving very well, stiffen up and or slow down the suspension extensions and the car will probally go quicker and faster What size, brand and compuond are the new tires? Inquiring minds want to try them
Posted By: go green
Re: SloMo Launch vid - 09/14/10 04:37 AM
Looks par course .
Smoking cool launch .
That's what you get with the flimsy stock suspension .
Look at 4 days in May video .
Super stock guys have been doing this fore years.
What camara are you using ?
Smoking cool launch .
That's what you get with the flimsy stock suspension .
Look at 4 days in May video .
Super stock guys have been doing this fore years.
What camara are you using ?
Posted By: thehemikid
Re: SloMo Launch vid - 09/14/10 06:47 AM
Quote:Quote:
Here's a vid from the last meeting.
http://www.youtube.com/watch?v=91dmTS-UvDc
...I may be wrong, but looking at that vid, at the (rear tire) air gap above the tire, ...once it reached full separation it doesn't change much. most of the springing is the rear "Tire" itself. After the 1st spring there's a slight spin looks like to me.
Posted By: 540DUSTER
Re: SloMo Launch vid - 09/14/10 07:38 AM
Tig,What does the car do when brakeing at the end of the run?I have an old Direct Connection chassis book that tells you how to measure for and correct bump steer problems. I think your toe settings are changing as the car goes up and down.
Posted By: MrSixpack
Re: SloMo Launch vid - 09/14/10 07:57 AM
My car has done the same thing since early 1970'ths and still does it.
I don't like it and don't know how to fix it, as I have to use the stock frontend parts.
Look at this T&T video from 1977 or 78. Wheelie
I don't like it and don't know how to fix it, as I have to use the stock frontend parts.
Look at this T&T video from 1977 or 78. Wheelie
Posted By: Tig
Re: SloMo Launch vid - 09/14/10 12:26 PM
Thanks for the reply's.
I don't know what camera the guy is using, he's the official track photographer, Googling Blackett photography may throw some light on this.
I'm going to replace the steering box and Idler arm over winter. They are the only thing I haven't changed on the front suspension. Front shocks are on the cards, maybe rears if finance can stretch to it. I also want to put a bigger cam in the motor too
The tyres are Toyo 10.5 w's. Similar in section width and Circ to the old 29.5 x 10.5 M/T's we had but with an 11.2 inch tread. http://www.toyo.co.uk/productdetail.php?identity=products&product_id=55
Ideally I would like a bit more shackle angle on the rear, we would have to fab some longer hangers and relocate them further forward. It's been on the "to do" list for some time
The car brakes strieght, with a tail wind we terminal @ 141+. Have to stand on the brakes hard sometimes if I've been looking at gauges
.
Seems I'm not alone with this "wobble". Does it cost some ET?
Thanks again for the help guys
I don't know what camera the guy is using, he's the official track photographer, Googling Blackett photography may throw some light on this.
I'm going to replace the steering box and Idler arm over winter. They are the only thing I haven't changed on the front suspension. Front shocks are on the cards, maybe rears if finance can stretch to it. I also want to put a bigger cam in the motor too
The tyres are Toyo 10.5 w's. Similar in section width and Circ to the old 29.5 x 10.5 M/T's we had but with an 11.2 inch tread. http://www.toyo.co.uk/productdetail.php?identity=products&product_id=55
Ideally I would like a bit more shackle angle on the rear, we would have to fab some longer hangers and relocate them further forward. It's been on the "to do" list for some time
The car brakes strieght, with a tail wind we terminal @ 141+. Have to stand on the brakes hard sometimes if I've been looking at gauges
.Seems I'm not alone with this "wobble". Does it cost some ET?
Thanks again for the help guys
Posted By: B G Racing
Re: SloMo Launch vid - 09/14/10 01:36 PM
Try this,set the suspension at 1" rise,0 to 1/32" toe,1/4 degree positive on the camber and 1 to 3 degrees positive caster.Tighten up the torsion bars to limit the travel or install front limiters for a maximum of 3" travel.Try and set the front ride height for 27+" from wheel lip to ground with no more than a 2" rake measuring at the front rocker(just behind the fender) to rear rocker as near to the tire as possible.Make sure before alignment that the pitman arm,idler arm and all tie rods and bushings are good,including the lower controll arms.Tighten the strut rods as much as possible.
Posted By: Tig
Re: SloMo Launch vid - 09/14/10 02:19 PM
Quote:
Try this,set the suspension at 1" rise,0 to 1/32" toe,1/4 degree positive on the camber and 1 to 3 degrees positive caster.Tighten up the torsion bars to limit the travel or install front limiters for a maximum of 3" travel.Try and set the front ride height for 27+" from wheel lip to ground with no more than a 2" rake measuring at the front rocker(just behind the fender) to rear rocker as near to the tire as possible.Make sure before alignment that the pitman arm,idler arm and all tie rods and bushings are good,including the lower controll arms.Tighten the strut rods as much as possible.
Sounds like a plan
, currently set @ 0 deg toe, 0 deg camber at 1 inch and 5 deg caster. 6 inch travel and 27 inch to fender lip through wheel C/L. Car doesn't usually have any stability issues unless it is really windy. Car also rides way higher than +1 inch when racing, looks like a gasser 
Do you use 20 degrees angle in and out to check caster? Won't tightening the strut arms alter caster angle too? Upper UCA's and strut bars are adjustable BTW.
Thanks
Posted By: moparacer
Re: SloMo Launch vid - 09/14/10 02:44 PM
Strut rods and more air in the slicks.
My car used to do that and solid strut rods helped it out quite a bit. Didnt eliminate it but cut it way down.
My car used to do that and solid strut rods helped it out quite a bit. Didnt eliminate it but cut it way down.
Posted By: Tig
Re: SloMo Launch vid - 09/14/10 03:07 PM
Quote:
Strut rods and more air in the slicks.
My car used to do that and solid strut rods helped it out quite a bit. Didnt eliminate it but cut it way down.
Car has Alloy adjustable strut bars with no bushes, when you say solid do you mean ones with no bushes?
Vids were taken early in the day, we were going up on pressure each pass.
Thanks
Posted By: mafo
Re: SloMo Launch vid - 09/14/10 03:14 PM
This is after I limited front end travel to about 4",it was not as bad as yours before and I don t really know if it helped performance but it looks better...
I have stock suspension with 1/2 shortened strut rods
http://www.youtube.com/watch?v=PUNba0TQt68
I have stock suspension with 1/2 shortened strut rods
http://www.youtube.com/watch?v=PUNba0TQt68
Posted By: B G Racing
Re: SloMo Launch vid - 09/14/10 03:20 PM
Quote:Quote:
Try this,set the suspension at 1" rise,0 to 1/32" toe,1/4 degree positive on the camber and 1 to 3 degrees positive caster.Tighten up the torsion bars to limit the travel or install front limiters for a maximum of 3" travel.Try and set the front ride height for 27+" from wheel lip to ground with no more than a 2" rake measuring at the front rocker(just behind the fender) to rear rocker as near to the tire as possible.Make sure before alignment that the pitman arm,idler arm and all tie rods and bushings are good,including the lower controll arms.Tighten the strut rods as much as possible.
Sounds like a plan
Do you use 20 degrees angle in and out to check caster? Won't tightening the strut arms alter caster angle too? Upper UCA's and strut bars are adjustable BTW.
Thanks
How did you achieve 6 degrees (I'am assuming positive) on the caster?Normally tightening the strut rods(but not to bind) will help positive caster.Usually Mopars are set with 1/2 to 1 degree nagative caster and need to go positive.Usually too much negative caster,bump steer or loose componants cause the condition your experiencing.I very seldom see stock Mopar front ends experience bump steer unless something is really screwed up.
Posted By: Tig
Re: SloMo Launch vid - 09/14/10 03:38 PM
Mafo: Yours looks way better than mine .
BG: Front suspension isn't all stock, I have adjustable UCA's with heim joints. This enabled me to get 5 degrees of + castor angle. The only poly bush is in the stock LCA, but these have stiffening plates. The strut rods are adjustable with a heim joint on the K end.
It could well be that something is really screwed up
All the ball joints are new as are tie rod ends. The only thing I haven't changed is the steering box and the drag link idler arm which I'm going to change in the close season. I have one more race to do this year next weekend so I'll see if I can rig up some sort adj travel limiting arrangement before then.
Thanks again
.BG: Front suspension isn't all stock, I have adjustable UCA's with heim joints. This enabled me to get 5 degrees of + castor angle. The only poly bush is in the stock LCA, but these have stiffening plates. The strut rods are adjustable with a heim joint on the K end.
It could well be that something is really screwed up
All the ball joints are new as are tie rod ends. The only thing I haven't changed is the steering box and the drag link idler arm which I'm going to change in the close season. I have one more race to do this year next weekend so I'll see if I can rig up some sort adj travel limiting arrangement before then.
Thanks again
Posted By: B G Racing
Re: SloMo Launch vid - 09/14/10 03:52 PM
Quote:
Mafo: Yours looks way better than mine
BG: Front suspension isn't all stock, I have adjustable UCA's with heim joints. This enabled me to get 5 degrees of + castor angle. The only poly bush is in the stock LCA, but these have stiffening plates. The strut rods are adjustable with a heim joint on the K end.
It could well be that something is really screwed up
All the ball joints are new as are tie rod ends. The only thing I haven't changed is the steering box and the drag link idler arm which I'm going to change in the close season. I have one more race to do this year next weekend so I'll see if I can rig up some sort adj travel limiting arrangement before then.
Thanks again
I'am going to take a shot here,using the solid strut to pull 6 degees positive is toeing in the lower control arms to a acute angle on the LCA mounting pin and bushing.Back off the strut to only 1 or 2 degees positive and see what happens.
Posted By: Tig
Re: SloMo Launch vid - 09/14/10 04:09 PM
Quote:
I'am going to take a shot here,using the solid strut to pull 6 degees positive is toeing in the lower control arms to a acute angle on the LCA mounting pin and bushing.Back off the strut to only 1 or 2 degees positive and see what happens.
Thanks
OK I can lengthen the struts an equal amount on both sides (same turns). Check castor and try again. I could easily do this at the track. Initially I used the UCA's to get the castor angle.Thanks for your help
Posted By: 540DUSTER
Re: SloMo Launch vid - 09/14/10 07:17 PM
Is your steering box and idler arm in the stock location?
Posted By: Tig
Re: SloMo Launch vid - 09/14/10 07:30 PM
Quote:
Is your steering box and idler arm in the stock location?
Yes.
I've also remembered that we heated the steering arms on the hubs and raised them when I was running smaller front tyres and more torsion bar load for a same rake / ride height
Wondering if thats causing a problem
Posted By: mafo
Re: SloMo Launch vid - 09/14/10 08:52 PM
Quote:
Mafo: Yours looks way better than mine
You are just polite, English as you are
Posted By: 540DUSTER
Re: SloMo Launch vid - 09/14/10 09:08 PM
You really need to read the mopar chassis book,maybe someone can scan it for you.If you bent the steering arms you got problems.You need to plot the toe cruve of the wheels(do one at a time)Once you know what the wheels are doing you can begin fixing it.I would bet that one wheel is toeing in when the other is going out when you land from the wheelie.Its like a oscillation thing.My car used to do what yours does when I hit the brakes at the top end,except my wheels wouldn't stop shaking until the car slowed down.It was so bad it broke the idler arm bushing and cost me a new pair of nickers.Is that the Kings english I'am looking for?
Posted By: Leon441
Re: SloMo Launch vid - 09/14/10 09:35 PM
Bob was hitting the nail on the head. You just did to Tig. I think you have too much ride height. 27" fender lip to the ground with whatever tire Bob said. I'll bet that gets the upper control arm level. You need the ride height adjusted so the upper ball joint is as far from the frame as possible. I always say level and nobody understands that becuase the control arm pivots are higher in the front than the rear of control arm.
I think you have too much ride height. Your A-arm is laying down to start with. Then you launch and the arm lays down even more pulling the top of the tire in more than the bottom. You can limit travel to help but initial problem is still there if this is the case. The ball joint on the control arm is too low to start with. Raise and lower the car with tire size not the torsion bar.
I don't know if you can get rid of all of this problem with stock parts. But a good start is to have the arms angled right to start with. I had this problem even with the upper arms level. I think my problem was too much caster. A little is good a lot is better. Not necessarily.
Fortuneately we went tubular on everthing in 1998 and the car was fixed. But, I remember those troubles.
Leon
Most people try to make their car too low. I think you might be a little high. Check it and see.
I think you have too much ride height. Your A-arm is laying down to start with. Then you launch and the arm lays down even more pulling the top of the tire in more than the bottom. You can limit travel to help but initial problem is still there if this is the case. The ball joint on the control arm is too low to start with. Raise and lower the car with tire size not the torsion bar.
I don't know if you can get rid of all of this problem with stock parts. But a good start is to have the arms angled right to start with. I had this problem even with the upper arms level. I think my problem was too much caster. A little is good a lot is better. Not necessarily.
Fortuneately we went tubular on everthing in 1998 and the car was fixed. But, I remember those troubles.
Leon
Most people try to make their car too low. I think you might be a little high. Check it and see.
Posted By: Tig
Re: SloMo Launch vid - 09/15/10 06:59 PM
Thanks for all the comments and advice. I've takin it on board, I have the mopar chassis book so I'll try to get my brain round it all over the close season and see if we can improve, if not eliminate the condition.
Thanks again.
Thanks again.
Posted By: Greg_Gessler
Re: SloMo Launch vid - 09/20/10 07:36 PM
Amazing video, perfectly clear picture. What camera takes video like that??