Visit The Dirt Forum for More Information

Author Topic:   Wrap-up shock question
jbenn
Dirt Roller

Total posts: 7
posted September 27, 2001 06:55 AM
I have an IMCA 4-link car that runs on a 1/4 mile dirt track. I want to know the effects of completely removing my 90/10 wrap-up shock. Has anyone else removed theirs? How did it affect your car? Did it set down too violently? Also I run a long AFCO torque link if that helps (35"). All help is greatly appreciated.

jammin
Dirt Administrator

Total posts: 3405
posted September 30, 2001 09:38 AM UIN: 16262997
When your rear end rotates upward and is under strain with spring pressure, if you don't use a 90/10, it will slam down, very, very hard. This could be very dangerous, especially if your running a lift bar and it breaks. I would not recommend it.

jammin

tmtrigg4
Dirt Roller

Total posts: 11
posted September 30, 2001 05:03 PM
I also run a 4 bar car. I have done this and it is more violent, espicially if you jump off the throttle. It will loosen entry up cosiderably. You may experience the car trying to spit the drive shaft out when you get out of the throttle. I only consider this as last ditch to make the car turn on a real heavy, tight turn racetrack. As Jammin said, it's not the best idea on the 4 bar cars because they move so much as it is.
If you look at the HOT chassis cars none of the ones I have seen use a 90/10 or have provisions for it. All of them are 2 link with push or pull bar.

jbenn
Dirt Roller

Total posts: 7
posted September 30, 2001 06:49 PM
Thank you to everyone that replied. I wished that I had heard from you before last night. The strangest thing happened. I pulled the 90/10 off and I did lose the driveshaft. However, it appeared that it was more from wrap-up under acceleration than from drastic negative pinion angle under braking. The front yoke somehow traveled completely into the transmission and jammed to where it didn't come back out. Afco torque link with 850# spring traveled 4". Until I pulled wrap-up shock off it had only traveled 2". With the front yoke stuck in the trans when the car set down the u-joints bound up and snapped the u-bolts. I had to take the front yoke out of trans. with a hammer; however, another one slides in and out with ease. What is everyones opinion as to what happened? The straightaway before this happened my car was hit in the right rear and went airborne. Do you think that couldve caused it? The car went a half lap more and the driveshaft came out. I need help and appreciate all who reply.
Thanks,
Jbenn

tmtrigg4
Dirt Roller

Total posts: 11
posted September 30, 2001 09:58 PM
What was the reason for pulling the shock to begin with? I've run 4 bar cars a long time, the rule of thumb for pinion angle is more than the 2 bar or leaf cars. I typically run 10 degrees. You may have broke over center and pulled the drive shaft out due to added travel. This will also cause the car to lose all it's bite when the car raises to its max lift. 4 bar cars have to have a lot of movement to engage the roll steer, this is what makes them fast not more bite. There is only so much bite that can be achieved by anti-squat period. Use the roll steer adjustments to gain moment thru the middle of the turn. When you are faster through the middle the exit will normally take care of itself if the car is close at all.

jbenn
Dirt Roller

Total posts: 7
posted September 30, 2001 10:21 PM
The car is way too tight entering the corner. I was hoping that pulling the 90/10 off would loosen it up. Will too much cross weight make it too tight going in? Ive got a lot with a lot of bite. 60.5 cross 325# bite. my RR ride height is too low also. It will definitely be fast if I can get it to turn going in without sacrificing forward bite.

dirtslinger66
Dirt Roller

Total posts: 13
posted October 01, 2001 12:12 AM
THAT WILL MAKE IT VERY TIGHT WE RUN 51% CROSS AND 80# OF BITE WITH A Z LINK

jbenn
Dirt Roller

Total posts: 7
posted October 01, 2001 10:44 AM
tmtrigg, check your private messages. I'd like to discuss some setup ideas and questions with you since we appear to be somewhat on the same page.

jammin
Dirt Administrator

Total posts: 3405
posted October 01, 2001 11:01 PM UIN: 16262997
Antisquat can come from different parts of the car. It isn't always what you see that gets you the bite. Depends where it is coming from.

jammin

Back to the Archives