12 replies to this topic

[imack]

Thinking of changing my unservo'd 8.4" metro turbo set up to KAD 7.9's.
Reason for this is to reduce twitchy handling caused by excessive scrub radius due to my dubious fitment of modified turbo calipers, spacers and 10" wheels.
Anyone swapped from 8.4" metro four pots, to 7.9" KAD's? Just wondered how the performance / pedal effort compared.
Don't know if KAD use metro piston size like minispares or minisport four pots.

[nicklouse]

its the same. offset aint it.

[imack]

its the same. offset aint it.

No, KAD fit the modified turbo discs to 8.4" mini drive flanges, discs are moved inboard towards the steering arms, so you get rid of the turbo flanges and wheel spacers that mess everything up.

[nicklouse]

then i would ba talking to them about doing the same but for 8.4s as you cant beat a bigger diameter.

[imack]

then i would ba talking to them about doing the same but for 8.4s as you cant beat a bigger diameter.

Totally agree about the larger diameter but I don't think the 8.4 setup can be made to fit inside a 10" wheel without adding wheel spacers again. They say the 7.9's won't fit all 10" wheels and some combinations known to work or not work are listed.

[imack]

KAD Caliper Info: Which Calipers do I Need?

Click here for instructions on fitting KAD calipers on your Mini.

Four pot calipers for Classic Mini:

KAD manufacture in total three different Mini 4 pot calipers according to their offset from the centre of the disc. There is one size of caliper to suit 12 and 13" wheels (marked "12") and two sizes of 4 pot caliper for use under 10" wheels using either 7.5" (marked "M") or 7.9" (marked "10") diameter discs depending on the type of 10" wheels fitted.

Most of the modern pattern wheels (Minilite, Minilife, GB alloy, 100+, Spectrum, MB Racing, Revolution, Revolite etc) have sufficient clearance for the 7.9" disc to be used which non standard size achieved by machining down an 8.4" (part GDB 90806) 12" wheel disc. This mounts to the late type Mini drive flange (21A 2695).
The Cooper S steel and reverse rim 10" wheels, Mamba and Magnesium Minilite must use the smaller disc size (7.5) which can be either the 8.4" disc machined down with late flange or Cooper S disc and flange (with our 'S' fitting kit of spacer washers and longer bolts). Many older types of wheel fall into this category also and in some cases wheel spacers must be added as these wheels were often initially produced to fit over drum brakes.

All of the calipers can be used with vented discs either as supplied (as a vented type caliper) or by the retro-fitting of the spacer kit and longer bolts, our calipers are designed to mount these to the late Mini flange by drilling the mounting holes from 3/8" (9.52mm) to 10mm. There is no vented option available for the S flange.

We do not use the Metro flange due to the upstanding lugs in the centre of the flange which prevent many Mini wheels from fitting. If you have bought our calipers and are wondering why you cannot make them, you should establish that you car has not been fitted with Metro flanges as there is an offset difference in the flange which will be causing your problem.

When fitting vented discs not supplied by KAD, the inside of the disc bell must be machined to provide clearance over the hub oil seal. The final dimension for the thickness of the face that the drive flange bolts to is 0.660". In 90% of cases the vented disc will now touch the steering arm where the arm forging bulges out around the mounting bolts, here it is necessary to either file or grind the bulging portion to achieve clearance of 2mm, there is plenty of meat in the arm at this point so strength is not a problem.

The hub/uprights are the same between the late Mini and the S type, but the drive flanges are different so its not possible to use the late flange with the S disc or vice versa.

[nicklouse]

so you are going to 10s?

 

road car? if yes you dont really need vents as they dont get up to temp to work correctly.

[imack]

Already on 10's with metro turbo brakes with ground down calipers spaced inboard, discs spaced inboard and wheel spacers to clear calipers.
Completely happy with current brake performance but the increased scrub radius caused by the wheel spacers and turbo drive flanges causes some 'interesting' pulling and weaving when overtaking and on heavily cambered lanes or on lines/repairs in the road.
Trying to get the scrub radius back to standard by loosing all the wheel spacing.
Wheel ET is 21mm, not sure what standard ET should be for 10" wheels on discs.

[Ethel]

As far as I'm aware the drive flanges just correct for the added thickness of vented discs. All Metros ended up on "Turbo" discs, not sure how much further you could move the discs inboard. If KAD are using turned down 8.4 vented discs, surely you could use ones that are still 8.4 and only need to look at the caliper spacing, at most?

 

You'd want the ET for 12" inch wheels if you're using the corresponding discs and flanges. Plenty of useful info here

[DomCr250]

Already on 10's with metro turbo brakes with ground down calipers spaced inboard, discs spaced inboard and wheel spacers to clear calipers.
Completely happy with current brake performance but the increased scrub radius caused by the wheel spacers and turbo drive flanges causes some 'interesting' pulling and weaving when overtaking and on heavily cambered lanes or on lines/repairs in the road.
Trying to get the scrub radius back to standard by loosing all the wheel spacing.
Wheel ET is 21mm, not sure what standard ET should be for 10" wheels on discs.

Are you 100% sure it's not the unequal driveshaft length causing your problems?  How much power are you trying to put down?  

[Icey]

road car? if yes you dont really need vents as they dont get up to temp to work correctly.

 

Agree with that. I'm about to switch out vented Metro 4-pots to original 8.4" solid disks and twin-pots as the Metro setup never gave enough feel (as they are always cold - even around Castle Combe).

[Pete649]

If you do decide on the KAD calipers be aware that the 7.9 inch setup will not fit under all 10" wheels. I have Ultralite wheels and got hold of the caliper template from KAD to check and there was no clearance so if I go down the KAD route I will have to fit the 7.75 inch setup.

[imack]

Car is currently putting out 138bhp according to Peter Baldwins rolling road,I'm aware of effects of drive shaft lengths, lsd, camber angles etc but when I fitted the turbo setup 25+ years ago I remember the car instantly having a very different twitchy /tramliney feel to the steering, nothing else was changed, just a conversion from 7.5" S discs to 8.4 turbo. This could only be caused by the increase in track / scrub radius caused by the flanges and wheel spacers.
I know people say vented discs are not required but I've always been very happy with the turbo brake setup.
I'm guessing the KAD setup will require a bit more pedal effort for a given retardation assuming their calipers use metro piston sizes.