Altered chassis problem

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489chevelle
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Joined: Sat Apr 28, 2018 7:39 pm

Altered chassis problem

#1 Post by 489chevelle » Sun Apr 29, 2018 9:27 pm

Hi people , My first post from Australia . I have a 125" Altered drag car has a decent 489 bbc on alcohol has run 5.39 @ 126 to the half on a new combo with no developement , it's after half track that things get a little wild and interesting so I'm hoping there are some chassis Guru's on this site . In top gear the car has an awful tendency to get loose and move all over the track and nothing i do can get it to hook up for a full quarter pass , the car is mild steel construction with solid rear and front , so no suspension . I checked tyre diameters and are the same , changing tyre pressures between 4.5.and 6 psi makes no difference .
What i have noticed is when i jack the rear on the diff center the right tyre raises up 3/8 " before the left and on the front the left raises up 1/4" before the right , Does this point to a twisted chassis ? . Is there any way to alter things to get it to work . With the engine torque and less load on the right rear i believe this could be the reason it is unloading the tyres . TIA for any comments that can through some lite on this issue . ps the nearest chassis constructor is 3000 km's away ....Cheers Mick

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John_Heard
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Re: Altered chassis problem

#2 Post by John_Heard » Sun May 20, 2018 9:55 am

Are other similar cars having problems too at the same track? Or is it just your car? - Just wondering if you're dealing with more a track prep problem than a chassis issue. I assume you've aligned the front end? Got any video of it during one of these passes when it's moving around? Any drive shaft RPM data from a data logger?

The difference in height when you're jacking it up doesn't sound all that excessive to me.

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