Originally Posted by sgp-chris
I have a question regarding the tweak of this chassis. I have now read all 139 something pages of this thread, and have found small posts here and there regarding tweak which impacts left/right ride height in the middle position. But I have yet to find a post which explains in detail what the issue is.
My hope is that some of you kind Xray guys, will take the time, and help me to understand what my problem is, where it's coming from, and how I can fix it.
I have tried to loosen all screws in the top and bottom of the front end, and tighten them again. This does not help.
I have about 0,4-0,6 difference L/R in ride height in the middle position. I would really like to have that as close to zero as possible.
The front springs are brand new, I have just changed them because i thought one had collapsed maybe. This is not the case.
I hope you can help me out
Any help will be much appreciated!
To make sure I understand, when you measure in the 'middle' position - where are you specifically measuring? At the front of the rear pod plate or somewhere else?
I measure ride height in 4 places:
- Front - under the front arm mount
- Front of Side Link - under the front pivot ball
- Rear of Side Link - under the rear pivot ball
- Rear - from the back of the pod plate (left and right side)
There are a number of things that can cause tweak:
Tires - F1 tires have thin inserts and a large air gap - the more you run them, the more uneven they get. They tend to cone like foam tires with heavy use. I mark my tires and don't rotate them for racing. On the bench, you can rotate them and see if that causes any tweak or put on a new set and see if there is a difference.
Balance - Make sure the car is balanced left to right when ready to run. Remember that the side of the battery with the plugs is lighter than the other side.
Wires - Make sure wires are not causing any pressure on the rear pod. I use TQ1000 (14g), anything more is not necessary. Make sure the sensor wire is not putting pressure on the rear pod - I cut the sleeve off and twist them.
Chassis - double check it is flat.
Bent Arms - The arms (especially the lower arm) tend to bend and become soft over time. Take the arms off and lightly flex them, if they show signs of being overly soft or not returning to neutral by themselves then replace them.
Collapsed Springs - One spring has collapsed.
Rebuild - For a quick or partial fix, loosening the screws (especially the castor plate) may work, however, I tear down the entire front end. It doesn't really take that much time (~10 min) and allows me to check that nothing is bending, binding or broken and solves 99% of front end issues.
Servo Mount - I run the car with the direct servo mount position. I will loosen these screws and retighten.
Tweak Springs - Check that they are not collapsed, or crooked (the set-screw is not in the carbon straight). I use a 2mm shim between the spring holder and carbon plate as a starting point with kit springs - this makes the springs just touch the chassis. I will tweak the car from there.
Side Links - Make sure they are free - a slightly tight side link on one side of the car is a tell tale sign that the rear pod is tweaked (re-adjust the pivot ball assembly).
Pivot Ball Assembly - check the pivot ball movement - too much slop (up and down) will cause odd ride height issues.
Pod Plate - make sure it's not bent, cracked, etc.
Inserts - On a rare occasion, the ride height inserts have developed some slop up and down - after a blown and locked up bearing in my case.
Tires - Usually the case, as mentioned before - they wear down and become soft. When replacing with new tires, I have gained 0.5 - 0.7 of ride height.
Even with a perfectly flat setup, after a couple of hard hits you may start to notice some tweak - 0.5mm is not too bad - 1mm or more and I'd start looking for the issue.
Hope that helps. Let us know.