Organized Drag Racing and Autocross Drag racing and autocross discussions and questions. Techniques, tips, suggestions, and "what will I run?" questions.

front end shake after launch

Thread Tools
 
Search this Thread
 
Old 04-29-2012, 07:43 PM
  #1  
Junior Member
Thread Starter
 
68rsss's Avatar
 
Join Date: Apr 2009
Posts: 3
Likes: 0
Received 0 Likes on 0 Posts
front end shake after launch

First run today my car launched and when the tires came back down they started shaking uncontrollably. I had to let off just after the 60 because it was so bad. Last year was the first year with the car and its never done that once. I checked all the steering linkages and everything up front and its all fine. Has anyone had this problem with theirs and what did you do about it?
Old 04-29-2012, 08:26 PM
  #2  
Moderator

 
AlkyIROC's Avatar
 
Join Date: Jul 1999
Location: 51°N 114°W, 3500'
Posts: 17,123
Likes: 0
Received 123 Likes on 104 Posts
Car: 87 IROC L98
Engine: 588 Alcohol BBC
Transmission: Powerglide
Axle/Gears: Ford 9"/31 spline spool/4.86
Re: front end shake after launch

Get your steering geometry checked. You want as much caster as you can get to help keep the tires straight. It also sounds like you have bump steer. Every now and then I feel a shimmy when the front end comes down but never bad enough that I have to let off the throttle

I limit how much suspension travel I have with some cable limiters. I have a bump steer kit but I've never had it accurately checked. Another option is to install a steering stabilizer.
Old 04-29-2012, 09:06 PM
  #3  
Junior Member
Thread Starter
 
68rsss's Avatar
 
Join Date: Apr 2009
Posts: 3
Likes: 0
Received 0 Likes on 0 Posts
Re: front end shake after launch

Thanks for the advice. How much travel do you have in the front? The front of mine is really low and has a lot of travel
Old 04-29-2012, 10:07 PM
  #4  
Moderator

 
AlkyIROC's Avatar
 
Join Date: Jul 1999
Location: 51°N 114°W, 3500'
Posts: 17,123
Likes: 0
Received 123 Likes on 104 Posts
Car: 87 IROC L98
Engine: 588 Alcohol BBC
Transmission: Powerglide
Axle/Gears: Ford 9"/31 spline spool/4.86
Re: front end shake after launch

I can't remember the exact measurement but the cables stop movement before the struts are fully extended. I still want enough extension so when the front end comes back down that the shocks start to slow the movement down and absorb the impact. I also play with shock settings. During T&T passes, I usually set them on full loose and the front end pops up very easily and I can carry the front wheels to the 60' mark. The spectators always like that. During competition, I stiffen up the extension to help keep the front end down.
Old 04-29-2012, 10:17 PM
  #5  
Junior Member
Thread Starter
 
68rsss's Avatar
 
Join Date: Apr 2009
Posts: 3
Likes: 0
Received 0 Likes on 0 Posts
Re: front end shake after launch

Think ill adjust the caster and put some cables on and t&t with different amounts of travel then
Old 04-30-2012, 08:29 PM
  #6  
Member

 
mod313's Avatar
 
Join Date: Apr 2002
Location: Hanover, MA
Posts: 322
Likes: 0
Received 0 Likes on 0 Posts
Car: Camaro
Engine: 305-150/254 combo
Transmission: TH350 or T200
Axle/Gears: Srange 12 bolt; 5.14 or 5.38
Re: front end shake after launch

Ed Quay has a steering damper kit that will stop that. I am assuming that you've swapped to either a Vega or S10 manual box? Either way the Quay kit will take care of that shimmy.
Old 04-30-2012, 09:05 PM
  #7  
Moderator

 
AlkyIROC's Avatar
 
Join Date: Jul 1999
Location: 51°N 114°W, 3500'
Posts: 17,123
Likes: 0
Received 123 Likes on 104 Posts
Car: 87 IROC L98
Engine: 588 Alcohol BBC
Transmission: Powerglide
Axle/Gears: Ford 9"/31 spline spool/4.86
Re: front end shake after launch

You might want to check the adjustment on the steering box also. It may be sloppy.
Old 05-12-2012, 03:21 PM
  #8  
Supreme Member

iTrader: (14)
 
greezemonkey's Avatar
 
Join Date: Jan 2004
Location: The "D"
Posts: 1,761
Likes: 0
Received 3 Likes on 3 Posts
Car: A Portly 85 Z28
Engine: 4.530 X 4.250 BBC
Transmission: under rated for this application
Axle/Gears: also under rated
Re: front end shake after launch

Originally Posted by mod313
Ed Quay has a steering damper kit that will stop that. I am assuming that you've swapped to either a Vega or S10 manual box? Either way the Quay kit will take care of that shimmy.


I had this problem and the ED Quay shock fixed it. I had 6 degrees + caster Tight new linkages and manual steering box 28 inch frt tires and lots of travel. it does work for a 50$ fix
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
customblackbird
Suspension and Chassis
4
08-15-2021 10:16 PM
Terrell351
Engine/Drivetrain/Suspension Parts for Sale
5
06-13-2021 01:13 PM
Amillionoh7
Suspension and Chassis
24
05-24-2020 08:01 AM
bellez77
Body
14
09-05-2015 08:39 PM
bamaboy0323
Tech / General Engine
25
09-03-2015 06:07 AM



Quick Reply: front end shake after launch



All times are GMT -5. The time now is 11:11 AM.