GT12 Help..

[stucartwright]

Mark
Did I understand you right...if you have side dampers the plastics struts seen in the car above need to be removed as they are no longer necessary?

[stucartwright]

Scrap that... Just read your message for the fifth time, understand. You are not suggesting this but merely stating the O rings are not needed if you have a side damper kit.

[northernerbill]

Yeh thats why I made a point with regards to "my" car. I understand they are to removed if you have the damper hop up and by me adding them back today I've immediately noticed how much stiffer the rear end is.

I have removed them again, BUT my only reason for fitting was the ball joints are loose enough to cause slop in the rear end in a fwd/backward left/right direction, which is amplified towards the axle area.

My reasoning was it was better to have a car that travels straight/true reliably rather than potentially wandering due to that rear end play. I rolled the arms off the balls when I removed them (one time only) and the car is new.

My sons car is new too and never had the balls removed and his has the same play, guessing its within tolerances so just me going overboard.

[SlowOne]

Take a thin plastic bag, one of those cheap ones you get parts in, not a thick one. Place the bag over the ball and pop the socket on.

As you pop the socket on it will cut a piece out of the bag that stays in the socket and removes the play. Check carefully that the ball joint is free (any binding will hurt the handling) and if it tightens up find a thinner bag. Cling film won't work it will stick to the ball! If you can't make it perfect, do one ball joint at one end of the arm. That will halve the problem.

I am like you, I hate things like this that are not perfect. However, in practice it will make no difference to the car. If you take all the play out you may find the car more difficult to drive - pan cars like a bit of play in some areas. Don't sweat a small amount of play, it won't hurt.

Or, play around with the plastic bag trick until you reach nirvana. Take the bag with you in the pit box. Each time you pop the ball off for repair or maintenance, repeat the bag trick. Make sure that the old bit of bag is not still in the socket or the ball joint will be too stiff to work - that one I learnt form experience! HTH

[stucartwright]

Slowone; so to conclude. You are saying keep the struts on and place bag plastic over ball joint and then pop them back on??

[shinytopman]

Disconnect the ball and socket place the plastic bag over the ball of the joint then refit the socket of the strut. Thus leaving a small bit of plastic bag inside the socket to act as a shim.

[northernerbill]

Originally Posted by SlowOne

Take a thin plastic bag, one of those cheap ones you get parts in, not a thick one. Place the bag over the ball and pop the socket on.

As you pop the socket on it will cut a piece out of the bag that stays in the socket and removes the play. Check carefully that the ball joint is free (any binding will hurt the handling) and if it tightens up find a thinner bag. Cling film won't work it will stick to the ball! If you can't make it perfect, do one ball joint at one end of the arm. That will halve the problem.

I am like you, I hate things like this that are not perfect. However, in practice it will make no difference to the car. If you take all the play out you may find the car more difficult to drive - pan cars like a bit of play in some areas. Don't sweat a small amount of play, it won't hurt.

Or, play around with the plastic bag trick until you reach nirvana. Take the bag with you in the pit box. Each time you pop the ball off for repair or maintenance, repeat the bag trick. Make sure that the old bit of bag is not still in the socket or the ball joint will be too stiff to work - that one I learnt form experience! HTH

Excellent tip, doubt I'd ever have thought of that lol. TBH the rear play is no worse then the front ball joint play in the steering arms which we live with.

I actually currently find these a bit trickier to set up. Coming from 1/8th off road racing, and 1/10th touring cars they both essentially have the same mechanical/moveable principals where as these cars are a tad different.

I drove mine for the very first time at my last meeting and apart from being a bit too slow on the long straight thought it handled fantastically, tight, responsive, and nimble, going round the course on rails compared to touring cars on tarmac.

[SlowOne]

Stu, Mr. STM has got it so I hope you get it too. Come back if not.

Bill, always glad to help! I'd like to tell you I thought that up on my own. Sadly...

[northernerbill]

Originally Posted by SlowOne

Stu, Mr. STM has got it so I hope you get it too. Come back if not.

Bill, always glad to help! I'd like to tell you I thought that up on my own. Sadly...

Haha thank you anyway.

Right then next queeries.

Last night I christened my Tyre Truer reducing the rears to 46mm (being the largest people recommended) and 45.5mm on the fronts. Rounded the corners and applied the contact tyre decals for the protection.

Ok so then I got out the ride height gauge aiming for 4.5mm at the rear and 4mm at the front, again based on info here and elsewhere.

Not suggesting they are correct and maybe coupled together very bad but thats what I ended up at last night.

I have the front independent suspension set up and found it quite straight forward balancing the O ring damping against spring compression to get the desired height.

The rear however through in the extra variant of the single rear central grub screw which I'm guessing is two things...pivot point and sag adjustment. I wound the grub screw all the way out, and then adjusted the springs until it increased the ride height to 4.5mm. I then wound in the grub screw until it contacted the chassis whilst unloaded.
So it has no sag currently and under load or not loaded looks like this from the back, any corrections, advice and how too's much appreciated as ever. I have blues on the rear and greens on the front.



Thanking you in advance

[SlowOne]

Bill, you're coming at this from the right end, so here's a bit more information...

Ride height is ride height and you've got that sorted. There is a slight 'curved ball' with the front end - your static ride height is also your static castor. You need to get both as close as you can to where you need to be.

Start with the static castor. With the car on the ground, fully laden, use a camber gauge to measure the static castor - the angle of the kingpin to the ground. I usually start at four degrees.

Wind the downstop grub screws well away from the chassis. Adjust the nut on top if the spring until you get four degrees castor. Adjust both nuts the same and together otherwise it all goes pear-shaped! Now wind the downstop grub screws all the way in until they just touch the chassis.

As a rule of thumb more castor means less turn-in but the car will exit the corner well, and less castor gives more turn in but less steering coming out. Find a balance you like and adjust it to the track features as you see fit.

Next, change the washers above and below the steering block until you have your ride height right. We're done here for now.

At the rear wind the centre downstop screw well away from the chassis. Adjust the springs until you have about 2mm of 'sag' or 'droop' (I call it droop) in the chassis. Car fully laden, adjust the springs until the chassis sits with 2mm of movement when you pull it up to the stops. Now screw the downstop down until it just touches the chassis.

Using the eccentric inserts, get the ride height you need.

Now you should have a car at the right ride height on which the suspension at both ends does not drop down when you lift it off the table/pit board. It should have the ride height you want at both ends. Get it like that before we get to the next bit.

You can now set the droop at both ends by unwinding the downstops. As a rule of thumb start with 1mm at both ends. Unwind the screws evenly on both sides, lift the car up until the downstops touch the chassis and slide in your ride-height gauge. 1mm droop means that what reads 4mm on your ride-being gauge ready to race goes up to 5mm when you lift the car up until the downstops touch the chassis with the wheels still on the ground.

Now you can tune the handling. Rear droop will give you weight transfer to the front - the more droop the more weight transfer but the longer it takes the car to settle as you come off the throttle to turn in. I run 1mm, David Gale runs 0mm as he likes the fast reaction he gets when turning. We both increase this if the track is bumpy as it smooths out the ride.

Front droop is usually left alone - 1mm seems to work for everyone.

The rear downstop is not a pivot. If it touches the chassis during roll you have something else wrong! As the car rolls it will sink into the suspension so the downstop won't touch. It will touch a lot in bump as the car moves up and down over bumps. Try adjusting rear droop and see what you like to have for your driving style.

I hope that helps, but where my explanation is obscure shout up and I'll have another go! HTH

[mark christopher]

Originally Posted by northernerbill

Haha thank you anyway.

Right then next queeries.

Last night I christened my Tyre Truer reducing the rears to 46mm (being the largest people recommended) and 45.5mm on the fronts. Rounded the corners and applied the contact tyre decals for the protection.

Ok so then I got out the ride height gauge aiming for 4.5mm at the rear and 4mm at the front, again based on info here and elsewhere.

Not suggesting they are correct and maybe coupled together very bad but thats what I ended up at last night.

I have the front independent suspension set up and found it quite straight forward balancing the O ring damping against spring compression to get the desired height.

The rear however through in the extra variant of the single rear central grub screw which I'm guessing is two things...pivot point and sag adjustment. I wound the grub screw all the way out, and then adjusted the springs until it increased the ride height to 4.5mm. I then wound in the grub screw until it contacted the chassis whilst unloaded.
So it has no sag currently and under load or not loaded looks like this from the back, any corrections, advice and how too's much appreciated as ever. I have blues on the rear and greens on the front.



Thanking you in advance

Refers to the manual for axle spcers and rider height, you have way too much spring pre load.

[northernerbill]

Mark I'll answer you first TOTALLY forgot about this, had the 3 dots in, swapped to 2 dots and the preload is sorted along with ride height

SlowOne. Mate thats a brilliant break down of it and I totally get it (for now, till I think of a new issue I'm unable to even comprehend yet )

I had to tweek your front description a tad as with having the front independent suspension (I don't think) you adjust castor at all (just camber with the shims) you don't even have the grub screws for travel limit. Its purely adjusting the spring in conjunction with the O ring to set ride height and droop.

Belting though as I now have ride height, droop (where wanted), well you get the picture.

Thanking you's

[shinytopman]

Hi Bill,
You might also wanna try moving your rear springs to the outer holes, rather than the inner holes.

[SlowOne]

Bill, same thing applies if it is the independent front end, you just do one side at a time. Get the four degrees castor sorted on both sides. Also, make sure that the amount of compression on the front springs is pretty much even on both sides - check how much thread is sticking out of the bolt as a useful guide.

Yes, if you change the camber strap you need to check it all through again, especially the toe in/out on the steering.

Note Mark's point too. Move the springs to the outer hole. If you are running the kit pivot height start with blue springs, if you are running the lowered pivot conversion try starting with yellow springs. Remember that when the grip is high you want to soften the car so it rolls in to the corner and lowers the CofG. Making the car harder will cause it to jack up and grip roll.

Using softer tyres has the effect of softening the spring rate. I will often leave the front springs as they are and go to a softer tyre when the front grip is up as it has a similar effect as using a softer spring. If you run your tyres down in the low 40s then this doesn't help as much. HTH

[Xracer]

An excellent 'how to' SlowOne, if only Schumacher had you writing the instruction notes there would be more happy racers out there!

I just wish Schumacher would now fix the slipping diff drive ring with the 'D' ring solution that has been around for donkey's years on LMP's! Yes my diff is built as instructed!
Oh, and a finger hole in the chassis to access the motor to help make gear mesh easier!

I'm sure others may be suffering some of the above niggles too.

[northernerbill]

Yep cheers guys this has been a massive help, its all well and good being new to this class, building the thing, being new at a club and then slowly getting areas of the car better as you dare to ask, but nothing beats maybe having the car a good way there near the start.

Here she is and thanks to you.

[Xracer]

Well all looks neat and organised but just one minor observation, why take the power leads all the way across the car? The shortest, lightest and most efficient route is to the left hand side surely!
Attachment 80543
Just to illustrate.

[northernerbill]

Yeh I hear you I just hate chopping ESC cables down short incase I want to use them elsewhere...........but doubt that will ever happen with this ESC, its so car specific.

[stucartwright]

So good to see newbie using this thread with affect...
Personally I wouldn't worry about the length of the cables, the difference won't be noticed when you race, purely cosmetic in my experience. Looks very smart and let the fun begin!

I've been away for almost a month working and tomorrow sees me return to West Kent for a very exciting time, my pal has his new GT12 car, also equally excited.

I am amazed quite frankly at how the new RW racing spur gear and pinion I got, mesh, to reduce my car to almost silence when I test it on the road nearby. It's amazing. Added to the new diff balls and increased side damper oil thickness, looking forward to seeing how she runs.


Will check in Sunday with an update, happy racing lads!!

[mark christopher]

The core spurs are made by rw.

I'd shorten the wire and fit 16 guage, alot lighter more flexible and very capable of carrying the current, personally I'd also loose the ifs and stick with the kit beam.