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MG MGF Technical - Trophy Calipers update

From previous thread as a reminder

>Finally got round to fitting the 4 pot AP calipers.
Had to use a 10mm spacer behind the wheels to keep my MG cup wheels. Also had to fit new studs that were 10mm longer to compensate.

Only problem I had was wheel arch rub, which was easily sorted by pumping her up to a ride hight of 320mm.<

*X* update *X*

Rob B, Mike H and David S asked for an update.

(Mike did you fit yours?)

Now had the calipers on for a couple of months. Have had no major problems with them.

But....the front end has seemed to be a little bit 'skittish' (is that a real word?). I wasn't sure if it has always been like this or after I fitted the spacers.

I did have 215 all round, but yesterday due to a punchure, had to buy a new tyre. Decided to buy two 195's to see if I could have her lowered again. Bearing in mind these tyres have less than 50 miles on them, the 'skittishness' has completely gone, and the very occasional 'squeak' when the old tyre hit the arch has also vanished.

Looks like she'll be getting lowered again :)
Richard P

Hi Richard,

I took the more conventional route of using the Trophy alloys, so no spacers required. I think you've made a wise choice going to 195s at the front, from a grip & handling point of view, as well as aesthetics.

Get on a track day, then you'll see how different your braking points are compared to standard brakes ;-) Although having said that, I still don't seem to noticeably out-brake Rob with his standard calipers grrrr!

Mike Hankin

Hi Richard,

thanks for the update! Good to hear that you are getting on well with the combination of wheel and caliper :o)

>> But....the front end has seemed to be a little bit 'skittish' (is that a real word?). I wasn't sure if it has always been like this or after I fitted the spacers. <<

In the original thread do you recall that I mentioned about the scrub radius (also known as the pivot angle radius)? The skittishness (I think that is a word!!! ROFL) that you've noticed is almost certainly down to this: there is a much greater moment of force now acting on the kingpin axis that gives this sensation of lack of stability. Pictures always help with explanations, and there's one here: http://www.mgf.ultimatemg.com/group2/suspension/wheel_options_for_the_mgf.htm#KingPinInclination

Interestingly, when you lower the ride height, the king pin inclination tends towards the horizontal, and in doing so will reduce the scrub radius - and this should help with the unsettled front end of the car. Narrower tyres will help anyway, and will reduce the amount of tramlining I suspect that you're also suffering from.

What's the ride height at present Richard, and how low do you intend to go?

BTW - any pictures? :o) :o) I am sure that the combination looks terrific :o)
Rob Bell

Anyone has experience with AP calippers/304mm discs WITH 16" square spokes alloys ??
I might be tempted.... ;o)
Fabrice

IIRC Fabrice, they're as much a nightmare as the 'Cup' alloys that Richard has had to use spacers for :o( It's the clearance between the somewhat bulky AP racing caliper and the inside face of the wheel spokes that cause the problems.
Rob Bell

Sent you a pic Rob.

Ride height is about 320-330mm at the mo, would like to go back to 290-295mm :)

R
Richard P

Thanks Richard - which address did you send it to? Hotmail?

Would be very useful to know how the kingpin inclination angle alters with ride height - particularly with the ride heights you plan! :o)

I've had my car down to sub 300mm before - the car looks awsome - but speed bumps become a real challenge! The ride height at present is about 330mm, which is pretty practical for my small enclave of Londinium! :o)
Rob Bell

I used your UCL address and it's been bounced back. Not sure if I've got your hotmail one. Can you mail me and I'll mail back.

Had 295 all last summer, had to be very careful, but like you say, it makes the car look superb :)
Richard P

Richard, the UCL account is now defunct - try robert dot m dot bell at kcl dot ac dot uk. Thanks :o)
Rob Bell

2nd time lucky ;-)
Richard P

Got it! Thanks Richard! :o)

Have to say, it looks terrific.
Rob Bell

This thread was discussed between 28/06/2005 and 30/06/2005

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