v8 fm kit

[rodsmx5]

hey guys ,,i have the 6 litre mx5 [the grey one]..and it is killing the front bushes like you wouldnt believe,,i have now fitted 4 kits and they all last about a month,,i dont know if it is because i am doing hard laps at wanneroo or what,,,,the yokohama ao50 s are rooted after 18 laps and the willwood rotors are cracked so i get the idea it is going hard but i do think the lower bushes should last longer..maybe i should get some made out of brass i really dont know
what do you guys think

[spikes]

motor mount bushes or suspension bushes?

[rodsmx5]

the rear on the lower arm goes first,then just after the front tear out[the ones near the camber adjuster washer.]

[NitroDann]

What are you using? Considered tube arms with rose joints?

Dann

[deviant]

First step I think I would call FM and see what they do on their track cars. I believe they built a V8 for tarmac rally so may have run in to some issues.

No way you should be destroying AO50's in 15 laps unless you are over driving them, have incorrect pressure or incorrect alignment. That it is tearing tyres up AND destroying bushes...something just aint right! Maybe something is binding up or doing funky things in the corners. What times are you running at Barbagallo? I seem to remember they are pretty decent so it must handle okay.

Wilwood rotors are big in diameter but not nearly thick enough for hard circuit work...you need thickness to cope with big heat. An MX5 is a light thing but you still get an almighty amount of heat in the brakes coming down from big speeds. Look for a 30mm+ thick discs...Skyline discs work well.

[16bit]

what size wheels do you have? if you are still running 15's it could be time to move up to a larger tyre with more thermal capacity. that said unless you are taking data on tyre temps we don't know if its an alignment issue or what.

at the same time ditch the wilwoods they are no good for track work.

if you have lots of cash get an ap racing 330mm front kit or a brember 313mm kit and put se brakes on the rear. if you don't try the yellow speed 330mm kit so we know it works and can also buy them

a few more specs of the car might help.

like what kind of bushing you are going through so fast - is it oem or something after market?

[Hellmun]

How are they getting destroyed exactly? Like are we talking abrasion and eventual breakage or flat out torn apart suddenly? That will give you some indication whether it's binding and being ripped or just plain not turning (assuming your using polyeurethane bushes). What angle are your suspension arms in relation to the front sub-frame just to get an idea whether you've got some unusual geometry happening? The V8 will give unique issues but you'd think the guys on Slicks with big power turbo's would atleast be approaching similar kind of issues with all the extra weight to keep them reliable. Have you weigh-bridged the car since the install?

A050's in medium aren't that soft either, I did the wakefield 300 in the wet plus about 9 trackdays...so that would put them at near-abouts 360 (138 in the wet) laps. What size tyres are you running? Mine were 225/50/15.

[spikey]

Rod give FM a ring and chat to Keith Tanner, he should be able to put you in the right direction, they have developed and race these V8 so would have lots of experiences on the matter.

[rodsmx5]

the car is doing well at the track,,55.4 short,,64.3 long...thats running 15-9 6uls with the 225 -50 yokos,but the tyres do boil after 15 long laps ,have been told to use 048s or the bridgys,,the rotors are just starting to crack a little,but they have done 300 odd laps and it is pulling up from 237 km coming over the hill so i cant really complain about the rotors...they are only 30 bucks from 949..the bushes are the aussie pro ones, the the orange pommy ones ,then the race ones from f.m...it always splits on the rear ones first and its right on the 90 degree bit if you know what i mean....the fat bit on the end of the bush.rips off and hangs down like shoe laces..its the f.m v8 kit so the arms hang at 90 degrees under no real stress and i have checked a made sure there are no dags or any sharp edges. the car is abit lighter than it was with the 1.6 and is still evenly balanced,,,i do run a bit splitter under the garage vary lip,,and that has helped with lap times ,but maybe it pulling the car down to much and really testing the bushes i dont know

[geofiz]

Rod,

Have you considered using delrin bushes? Mazdaspeed use them as their high end competition bushes.See the attached link. You should be bale to get them through the club, as we have some arrangement through Mazda WA

http://www.mazdaspeeddevelopment.com/miatasuspension.html

Let me know if you need more information.

Russell

[manga_blue]

Something very odd here. I was told the MX5 lower FCA bush sizes were very over-engineered originally, much bigger than a Commodore V8 for instance.

[deviant]

Your rotors still should not be cracking or even showing much wear. The turbo race car I just sold to Pete Corboy (previously owned by Rob Hagarty) has Subaru STI calipers and Skyline GTR discs which are 30mm thick....the same discs have been on that car for 5 years of racing and tuning days on full race pads and they barely have a lip on them. Terminal speed on the long track is about the same and that car weighs approx 1000KG. You need much thicker discs for those sorts of speeds and times. Even with those great big Skyline discs and air ducting from the front bar they can be seen to be glowing bright orange at night...Imagine what your poor 20mm thick discs are putting up with!

Be a little wary of just fitting solid bushes etc as they can be a bit of a band aid solution. If 'something' is moving under load or binding up fitting solid bushes will just shift that movement somewhere else which can cause you more problems! With a light car you do want to keep a bit of compliance in it.

I have seen the lip ripped off bushes before but not sure what causes it. I have only seen it on hard dríven cars. Maybe it is whatever the bush is in is sliding up and down the bush due to the load of the high grip tyres.