rear end !!!

[mrtecone1]

First time on here for me so happy new year to everyone and on with my story.
I decided to build an MRS for track/tarmac rallying about 3 months ago,I used it for a short time as it was a very tidy road car,I have to say they are more fun than I expected ,it had after market suspension ,a brace under the centre of the car and some kind of camber set up on the front, I found it to under steer in the wet but not evil ,you can also hold a good slide,the main problem was lift off over steer, as if something on the back had come lose ? It had a long MOT so maybe some thing had been missed.
As soon as I can load pictures I will start to show the build.
At the moment it has had a full custom cage fitted ,I have a complete EP3 as a donor yes she will be having a K20.
Innovative mounts are here in a box waiting.
I had a alloy fuel tank made to fit the front due to the K20 set up being around 170 kilos,but I will get rid of the air con and Honda p/s pump.
A fully adjustable pedal box and AP 4 pot callipers front and back to give me a bit more control with the set up.
AVO 3 ways are being made over the next few weeks they have been a great sponsor for many years.
I also have an Mfactory gear kit coming as the gearing on a standard box is not so good,good for 170 mph !!
Will be running a Kpro ECU on its way.
Exhaust manifold is proving tricky as I still need ground clearance.
I would also like Megan rear arms should help set the car up a bit more ?
But does any one have any ideas regarding the lift off over steer. Hope I haven't bored you all to much.

[Topdownman]

Welcome,

Sounds like quite a project you have there and looks like you know what you want!

Looking forward to seeing some pictures as you go.

What tyre sizes, makes and pressures are you using?

[mrtecone1]

Team Dynamics supply my wheels,I will be running 7 x 15" Pro 1.2 I hope to use a Hankook T91 or T71 ,around 21 psi ,thanks for the welcome.

[ChrisGB]

Lift off oversteer could be normal. These cars have the engine a long way back in the car. Once that weight gets rotating, it is not easy to catch and it will get rotating very quickly if you back off with it heavily loaded mid corner, or overdo the trail braking. Tyres and geo are key areas. Reducing rear roll stiffness could help tame the rear, but may also increase understeer.

The K20 weight shouldn't upset the balance too much, I've got a big chunk of engine and box behind the bulkhead and it seems to be nicely balanced, but with more traction than it used to have with the stock engine. Keep us posted on the build!

[mrtecone1]

Hi Chris,I hope the lift off over steer inst normal ,did forget to say it only seams to do it /pull to the left rear. Regarding engine position, I like that it is so in front of the rear wheels ,I like the fact your car seams to have more rear end grip or traction. I agree with a proper geometry set up,I will let AVO do that side of it.

[stupink]

They're definitely prone to lift off, but I've never had lift break traction, but if tractions broke and you lift it can flick it back to a spin the other way. Geometry is probably out or current tyres are poor. Good tyres and accurate adjustments transform these cars so much.  Also under steer will take down on decent rubber, it will still under steer on tight turns or very high speeds but not excessively. And can be corrected with a little more or less power  s:) s:)  will only happen on the road not track where there's more grip(from my limited experience)

[ChrisGB]

Hi Chris,I hope the lift off over steer inst normal ,did forget to say it only seams to do it /pull to the left rear. Regarding engine position, I like that it is so in front of the rear wheels ,I like the fact your car seams to have more rear end grip or traction. I agree with a proper geometry set up,I will let AVO do that side of it.

Could be a geo problem, or perhaps a failing bush. I've spun mine near 720 degrees oo a handling day, but it took some serious provocation to get it to go round, silly amounts of heavy trail braking deep into a 70mph corner. What I've found does upset it is getting on it too early in the corner so the rear is sliding, then getting off it too quickly, but that is something that should only happen when trying to provoke a spin, or if you are taking the  spiss piss spiss  with the balance.

[weeJohn]

Looking forward to seeing the fuel tank set up, any visions of how it will look and fit?

[mrtecone1]

Hi Weejon,I have already had the tank made,it sits low very close to the steering rack,and is full width ,should help with the handling !!

[6100art]

Hi. Has it got a LSD as this is a feature of that, keep your foot in.

[mrtecone1]

My car has got a DC5 type R slip going in it ,I have since found a rear arm had a really bad rubber in it ,so much play it was always going to feel strange.