Touring Car tweak help (Tamiya 417v5)

[cs8sz]

Hi,

Please help!

I have a tamiya 417v5 which for some reason is massively tweaked. If I take all the wheels off and put the chassis on a board it is flat as a pancake. If I then setup the ride height to be 5.5mm on the rear and 5 on the front making sure all the spring collars are identical left to right, and then put it on a tweak station the car is miles off, and requires loads of extra pre load on some of the shocks.

If I don't use the tweak station the car is awful, is there any other way around this does anyone else have this?

I have made sure all the shocks are identical lengths.

Also it really messes up trying to get the correct droop due to the chassis being at different heights.

Thanks in advance

Chris

[shaun m]

Have you tried it on the set up board using 10mm blocks under the chassis ??

Basicly to get the tweek out of the chassis , put the car on the 10mm blocks under the fr - rf block or under where the droop screws are , undo the top deck screws , get someone to hold the car down flat ( pushing on the shock towers ) then re-tighten the top deck screws in a diagonal way..

you should have a totally flat de-tweaked car ..

[cs8sz]

Hi,

No I haven't tried that, although if you put the car on a sheet of glass the chassis is dead flat.

I will certainly give your suggestion a go anything to try and get rid of the tweak!

Thanks Chris

[Matt Butcher]

Yes check your downstop/ droop settings, make sure they are the same left to right.

[cs8sz]

The problem with this much tweak is that if you measure the droop with a gauge, then put the wheels back and and make sure that both rear tyres touch the floor at the same point by lifting the rear end, then it is miles off and I end up adjusting the droop screws to make sure that both tyres leave the floor at the same time.

My car is seriously strange, but then again all the touring cars I have owned have always had similar problems.

Thanks for all the input.

Chris

[Joe_K]

I'm not sure exactly what the problem with your car is but you could look at a couple of things:

1) Make sure that the car is set up the same on both sides (left and right) - make sure the upper arms are the same length, make sure they attach to the same points on the chassis and rear hubs. Make sure that the roll center points (where the lower wishbones/arms attach to the chassis) are of the same type from left to right and that they're the right way round. If you have rear hubs with vertical ball studs (pointing up rather than forwards/backwards) then make sure each side has the same amount of spacers (if any). Do the same for the front.

2) Take the shocks off the car. Put the car on 10mm blocks (or something you know the height of) and measure the droop, make sure that the droop is the same from left to right. Make sure that the amount of thread protruding from the wishbones onto the chassis is the same from left to right, if it's not then the wishbone is bent or moulded out of shape in some way (or the attachment of the hub to the wishbones may be screwed up or something). Make sure that the wishbones roate freely, look at the rotating bits (hinge pins, attahment to chassis, attachment to hubs/steering arms) and make sure that nothing is tight there.

3) Look at the shocks, measure them and make sure that they're the same length. Make sure that they both rebound (the outwards movement of the shock) to the same point and measure again.

Make especially sure that the car is built exactly the same (and correctly) on both sides, I've bought a few cars second-hand and had to totally rebuild them due to them being mangled by the last owner. Worst example was an Mini M05 (Tamiya) most of which wasn't actually Tamiya parts. Spent as much returning it to stock Tamiya state as I would have buying a new M05. Oh well!

[shaun m]

my moneys still on saying the chassis is tweaked , let us know what you find ..

[JimboJames1972]

Weight balance could also be a factor.

With modern TC layouts we have the cells down one side and electrics down the other. Depending on the type of battery/electrics you have, and where you have to locate them on the chassis, you probably won't have an even left/right weight balance.

If the weight balance is out you will need to compensate for this with shock pre-load. Unfortunately, if you then need a significant difference in pre-load from left to right you will get the mis-match in chassis ride heights and droop settings you refer to.

Try to get the weight balance equal. Mark the centreline of the chassis and balance it on two upturned drawing pins (if you don't have chassis balance pins). Move your electrics about or change your cell position or add stick on weights to get an even left/right balance. Once you have done this, then you can check the rest of the build geometry.

Hope this helps,

James

[cs8sz]

Hi Guys,

I did already check the left to right balance a few weeks ago and added some lead to the outside of the LIPO pack to balance the car 15g I think.

Last night I put all the pre-load for the shocks the same left to right and setup the ride height 5.5mm on the rear and 5mm on the front, the chassis was then level. However when I put it on the Hudy tweak station is was miles off, I did also swap the shocks left to right to see if that made any difference and it didn't.

I will certainly go through Joe_K suggestions and also shaun on the chassis tweak although it does seem flat.

Thank you so much for the input I very much appreciate it.

Chris

[smokes]

Hi My 415 had this problem. The car wasn't tweaked the spring lengths were different.

Also check that the shock lengths are equal and the shock rebound is equal as this compounds the the tweak issue.

Also chaeck the left to right balance is equal irrgang racing make som balance buttons that do the trick.

[cs8sz]

Hi Guys,

I had yet another look at my car and I discovered thanks to "smokes" that the rear springs were different rating they are meant to be HPI silver springs, I managed to use my kitchen scales as a way to measure the poundage of the springs. By compressing each spring 1cm and then seeing the weight required on the scales.

I changed the springs for some HPI blues, but annoyingly it hasn't made much difference!

Thanks for the help.

Chris

[qatmix]

Have you tried a different board? A guy at our club has a glass board that had a bow in it and that was the cause of his tweak as he assumed it was flat and would straighten his car on that.

[ceejay21]

i de-tweak all my tc's the same way.

get yourself a completly flat surface. make sure its clean as bits of crap will affect your measurements.

make sure there are no screw heads or bits protruding from under your car e.g. totally flat.

put it onto the flat surface and loosen all the top deck screws. make sure you loosen the shock tower screws too as they move about within the screw holes enough to cock up your setup.

get yourself something long and flat, e.g. a peice of steel rod.

place this ontop of the shock towers on the bits above diff and spool.

put a reasonable amount of pressure on the bar and tighten the top deck screws and any other screws you have happened to loosen.

now you can set your droop and things properly. using a bar on setup blocks sometimes causes problems as it just bends the chassis the other way

check for wear on the bottom of your chassis as sometimes you can make things worse.

[drop test]

I had an mi4lp that I was having very similar issues with. Turned out to be a internally delaminating chassis. Months I was scratching my head as to why I could tighten the top deck with the car on the tweak board and after set up it seemed to have moved. HTH.

[smokes]

Use float glass for flat surface a wooden board will never be as flat as glass due to mositure absorbsion