XRAY - Model racing cars

Just built my t4 and done 1 event with it. Noticed there is some serious tweak under the battery and in the front right.

I've done all the screws up in the correct order, got someone to press down on the chassis while I do up the top deck hoqever still tweaked.

Any ideas ?

How are you determining the tweak - eg laying a ruler along the bottom deck?

Putting the car on a flat surface and pressing down on the chassis. The car will lift the opposing side and you can hear it isnt flat.

Also, pressing on the rear shock tower and pushing down on the front, the front right of the car is off the flat surface

Ok, not impossible but not normal for a new chassis plate to be tweaked. You may have done some of the following but I suggest…


1. I may be doing it wrong but I have always found that there is some lateral movement when pressing the plate – even though my Hudy setup station is telling me that tweak is zero. Hence I never use that method; for a quick check I lay a metal ruler along and across the plate – so you might want to try that (undo the 4 shock absorber bottom mounts). If it lays against the plate for the entire length then your plate is not tweaked.
If it is showing flat then re-attach the shocks and check again to see if the shocks are causing the problem.

2. If you have setup wheels then fit those; otherwise your ordinary wheels will do. The 4 shocks should remain undone from their bottom mount. Lay your rear axle on one of the droop setting blocks. Then from the front, looking to the rear, slowly slide your ride height gauge under the car (along the centre line) until the wheels leave your setup board. Do they leave the floor at exactly the same time? If they do then unlikely that that end of the plate is tweaked.

Reverse the car and check the rear axle.

For me, a minor difference of the two wheels leaving the setup board, say up to 0.5mm, is fine. (Others might disagree!!)

This is probably eggs and sucking but you should have a battery on the chassis for the above.

3. Now if the car passes 1 but fails 2 then re-check your downstop settings to ensure they really are the same on both sides of the axle (making sure the A arm is really free and not sticking) and then redo 2.



If your are failing 1 and 2 then I would start again. IE loosen all the screws in the top deck and underneath the chassis and put some pressure/twist on the plate to try and flatten it, then re-check with the ruler.

If the plate remains warped then I suggest you call your supplier; otherwise hopefully continue setting up the car

HTH

Not teaching how to *** :-) *** eggs either but I saw a gentlemen de tweaking he's car with cell tape still in easily done!

How I de tweak mine, I obviously slacken off the top deck screws then using my plastic toe part from my hudy setup perfect for pressing down on the shock towers then retightening my top deck screws.
I always clean my board with brake cleaner first to make sure she's clear.
U can slacken off the shock towers from the bulkheads before doing the top deck then de tweak car on the setup station u can get tweak in the shock towers too, I have never had issues with either way.
Also make sure with the screws out a mm on the top deck it moves freely "rattles around a little" if not then you'll never get rid of the tweak!

I always loosen my top deck screws after my last final or testing just incase, but I have a some big whoopsies with the t4 and I've had zero tweak plus legendary zero breakages.

Ok to fully detweak

1.Loosen the top deck screws
2.Loosen the 8 screws holding the 2 front and 2 rear upper clamps with the roll centres
3.Undo the shocks from their lower joints.
4.Take off the front bumper and remove the 2 rear bodyshell holders
5.Loosen all the screws on the bottom of the chassis
6.Remove the aerial tube from the holder and lay flat


7.Turn the car upside down and lay on your setup board. Starting at the front or the rear, tighten the chassis screws, moving from front to rear or vice versa. As you do this, with your “spare hand” press down on the centre of the chassis; not too hard but enough to create a pressure on the chassis.

8.Turn the car over and tighten all the screws you loosened, starting at the same end that you tightened the chassis screws. As you tighten the top deck screws push down on the front and rear suspension holders. Easier with two people but on your own I put hand on one suspension holder and my arm on the other one.

9.Set your downstops. I always then use the method in my previous post of sliding in the ride height gauge to ensure the two wheels on the axle are leaving the ground at the same time. If they are not then something is wrong.

10.Check and make sure your 2 shocks on an axle are symmetrical in measurement

oGap between the lower shock ball joint and the end of the threaded part of the shock rod is the same (the manual recommends 1mm)
oPreferably using a vernier gauge, the lengths of the shocks, compressed and extended, are the same
oThe measurement from the top of the shock adjuster nut and the bottom of the lower shock cap should be the same.

11.Fit your shocks; loosen your roll bars; place on setup station and check tweak (should be fine )
12.Adjust your ride height to desired setting. Recheck tweak on setup board
13.Tighten roll bars and recheck tweak

Sorry I omitted the following comment.

Whilst XRAY state in their excellent setup book that you remove tweak by adjusting the shocks on the setup station, I disagree with this. Doing this is masking a fault. I accept it is an option during a meeting to resolve tweak when you do not have the time to go though the detweaking process. But when I am setting up my car before a meeting, if I see tweak on the setup station I do not adjust the shocks, I go through the detweaking process and always then end up with a car that placed on the setup station does not exhibit tweak.

The reason for tweaking the car on tweak station is for weight, not a twisted chassis!
If ur chassis is flat on the board, u'd never de-tweak through the shocks just setting weight evenly!

I've done all of the above and still cannot eliminate the tweak. I took the chassis off and put it on a flat glass and the chassis itself is not flat.

Is there anything I can do ?

Assuming you did not have an almighty crash in your one outing I would take the chassis back to your retailer and request a warranty replacement.

The car has driven ok. No crashes but it's so annoying having a new car with a tweaked chassis. I'm going to contact the place that I bought it and see where I stand.