MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGF Technical - Brakes again: Calliper piston areas

Hi folks - a quick question - anyone know the diameter or are of the rear calliper piston? I know that the diameter of the front caliper piston is 54mm...

Thanks!
Rob Bell

Rob,

Try RP

Paul
Paul Wiley

I'll drop him an email Paul, thanks
Rob Bell

Rob,

Can you keep me in loop as to your eventual decision and numbers, as its been quite fascinating so far the physics and reality.

Paul
Paul Wiley

No problem Paul. BTW, I've summarised my understanding of brakes and balance here: http://www.mgf.ultimatemg.com/brakes/big_brakes/Big_Brakes.htm
Rob Bell

Rob did you establish what the Trophy brake bias is set to, given the standard F 60:40 front to rear?
Steve Ratledge

No - but I believe that the Trophy has a bias valve with a different part number...

There isn't anything more on this topic in any of the literature I have. :o( Has anyone else found anything?
Rob Bell

Rob,

Try RP again.

The larger piston is on disc exit!

I would also check Hawk pads as they go to 800deg and suitable for road (I find they do squeal) greenstuff are around 500deg which I think is the reason for so called disc warping but really pad material.

I've no confirmation on wheel velocity!

Paul
Paul

Hi Rob,

just had a look and quick fly over the written scientifics :)
(You will know, I didn't read all in details) ;)

I like the brake mistake section.
Well done though !!
:o)

Missing the message:
*If you're in daubt, leave it out !!*

Regards
Dieter
Dieter K.

Cheers Guys :o)

>>*If in doubt, leave it out !!*<<

Dieter, I especially like this line!!! :o) I'll put it in somewhere...

RP's been out of circulation recently, but I'll drop him a mail today to see if he's back at work :o)
Rob Bell

Rob,

Great read- I wonder if reaction will be same as my general posts?

A few interesting areas are the amount by which rears are downgraded to avoid rear will lock in first place 5% 10%? its not even maximum to start- with TVR it appears rears are actually too good?

Modulation - having on/off brakes may not be best to acheive 15% slip? Tyre force at 15% say 1.2g but locked say 0.8g?

The effect of ABS and EBD and a decel hole?

Silicone DOT 5 fluid?

Paul

Paul Wiley

Paul, once 15 degrees of slip is exceeded, it depends on the tyre how much grip is lost and how quickly. Some tyres may have a rapid drop off of grip - perhaps being only capable of decelerating 0.2G, whereas others (the more progressive tyres), may generate more - somewhere in the region of 0.8G...

But interesting discussion points there:
1. Brake modulation/ technique (I'll have a look to find some good links on the web)
2. Tyre performance and slip angles - there's already a page on the site that deals with slip angles - might just add another small section relevant to braking... [ http://www.mgf.ultimatemg.com/chassis_and_handling/slip_angle.htm ]
3. ABS/ EBD... That's going to need some research on my part!
4. Silicone DOT 5 fluid - and why not discuss DOT 5.1 fluid (the stuff that I have in my braking system)?
Rob Bell

Rob,

I've been informed very quick!

http://www.stoptech.com/whitepapers/abs_bigbrake_122701.htm

Only DOT 5 is a problem, rest need regular changing
Castrol SRF is max 18mths.

Paul
Paul

Great explanation on another almost forgotten braking process.

Why to release clutch and kick the brake like a silly horse in emergency case,
http://www.stoptech.com/whitepapers/abs_bigbrake_122701.htm

With or without ABS. :)

Regards
Dieter


Dieter K.

This thread was discussed between 06/02/2004 and 13/02/2004

MG MGF Technical index

This thread is from the archives. Join the live MG MGF Technical BBS now