37 replies to this topic

[R32Egor]

Hi all,

 

I got a set of 4 pot metro brakes (i think) with the spacers to fit vented discs.

I have a 1996 SPI with the standard setup now.

 

I checked on Mini spares and they say that the drive flange - NAM6450F -   must be fitted to enable the vented discs to be used.

I read an old mechanical tips in an old mini magazine from keith calver that there is no need to fit these flanges if you have 8.4 inch discs as standard.

 

Whats correct? any ideas??

 

 

 

[Spider]

If you are retaining the stock unvented discs, then you don't need to change the drive flange, but this won't work with the calipers you have.

If you are fitting vented discs, then yes, you need to change the drive flange to the NAM6450F.

I'll add, on a Mini you really don't need or want vented discs. They add to the un-sprung weight and increase the track adding more load to the wheel bearings, hubs and ball joints as well as increasing the scrub radius, that'll make the steering heavy and twitchy.

[nicklouse]

As above.

 

don’t forget there were 3 types of 4 pot Metro calipers. Types A and B that were for solid discs. And then there were the type for vented discs. For vented you need the correct drive flange. The others use the standard sized one. Locating lugs on the Metro drive flanges need to be removed for most Mini wheels.

[mab01uk]

From Keith Calver's website:-

 

Metro disc brakes

"There’s always a bad egg in there some where and the Metro hub/disc set-up has one…it does weird things to Mini suspension geometry. Mainly manifesting it’s self as horrendous bump-steer and huge positive camber gains - even with standard bottom arms; worsening with a much lowered ride height. Bump-steer is so bad that sudden bumps caused by anything including mastic joints in tarmac can fire the car across to the other side of the road. This is accentuated by bigger and bigger wheel/tyre combinations. The worst inevitably being the ‘vogue’ thirteen-inch rim diameter and low-profile rubber. 

The reason is relatively simple. The Metro has a significantly different king-pin inclination angle to allow for a track increase of some 1.75”, and very deeply inset wheels as fitted to Metros. This is juggled in an effort to reduce bump steer to tolerable levels and give some ‘feel’ to the steering but retaining a 'lightness' without resorting to a bus-sized steering wheel. When applied to a Mini, this goes completely hay-wire. Funnily enough, there seems to be two types of Metro hub. I have fitted several sets and noticed this was worse with some than others. The king-pin angles are different, but there are no distinguishing features at all. All casting numbers are the same, and indeed have been sold under the same part number since inception of the Metro. Weird, huh? I believe it was something to do with the vented/non-vented discs set-ups on earlier Metros. 

So what’s the answer? None that’ll completely sort the problem. Using negative camber bottom arms (adjustable ones on racers) will help sort camber problems, as will maintaining a reasonable ride-height. Using wheel rims with the greatest inset you can find will help too. If wanting to run a real low ride-height, run a race car, use sticky-out wheel rims (because you’ve got them) or retain ten-inch wheels, I STRONGLY advise using the pukka Mini set-up. 

The last point to make is about connecting flexible brake lines. Metros use two where Minis have one. This is because the standard Metro system has a fail safe facility where if part of the system fails, the calipers are split so two of each four in both calipers will still work. This isn’t a problem as Mini Spares/Mania sell a conversion pipe kit to feed both ports on the caliper from one pipe on the subframe. Saves a lot of mucking about."

More here:-

https://calverst.com...-fitting-discs/

Edited by mab01uk, 13 October 2023 - 09:24 AM.

[GraemeC]

That's more about the hub than the brakes though Mab01uk

[mab01uk]

That's more about the hub than the brakes though Mab01uk

 

It's also info about the flexible brake lines and the Minispares conversion pipe kit though....plus others that read these posts may not be aware of the Metro hub issues.

 

BRAKE HOSE METRO 4 POT TO MINI BRAIDED CONVERSION KIT:-

https://www.minispar....aspx?pid=35514

Edited by mab01uk, 13 October 2023 - 01:31 PM.

[absx2]

Trust me I`ve been there so take it from me don`t waste your time and money.

You end up with lifeless feel, less bite and longer pedal travel and all you have to show for it is less money and a couple of extra kg`s where you don`t want it.

[Gaz66]

I've had a solid metro disc setup on a mini and never encountered any of this bump steer malarkey.
I used the mini steering arms and the bottom arms were made 3/8" longer which gave me about 1° neg camber.
Having said all that, don't bother. There's better brakes out there.

Edited by Gaz66, 13 October 2023 - 02:46 PM.

[nicklouse]

I've had a solid metro disc setup on a mini and never encountered any of this bump steer malarkey.
I used the mini steering arms and the bottom arms were made 3/8" longer which gave me about 1° neg camber.
Having said all that, don't bother. There's better brakes out there.

But was that with or without using the Metro hub? 
 

what you have said you have used would not change anything in the suspension because you have not changed anything.

[Gaz66]

Metro hubs. All I had to do from memory is drill out the mini steering arms a smidge to get them to fit the hubs.
The bottom arms were lengthened to negate the positive camber.
As I said I had no problems with the handling on 12" wheels.

[r.tec]

Do you know this: https://www.minimani..._pot_conversion .....or here: http://www.dummett.n...rake_discs.html

 

Edited by r.tec, 13 October 2023 - 05:29 PM.

[Gaz66]

Do you know this: https://www.minimani..._pot_conversion .....or here: http://www.dummett.n...rake_discs.html

Good write ups there. The second one suggests what I did. 👍

[absx2]

As I said I had no problems with the handling on 12" wheels.

 Sorry mate, you didn`t drive it hard enough 

Hideous bump steer on Metro hubs even with l.25 degree of negative camber on 165/60-12 A539 Yokohama`s on standard Rover Minilights

literally fighting with the steering wheel on hard acceleration in second gear on a bumpy road with vented Metro 4 pots and hubs with mini steering arms and totally cr*p EBC pads.

Swapped back to standard with AP pads and it was a joy to drive again with no bump steer. The Gas Spax shocks coped with the bumps better due to the reduction of the unsprung weight and the brakes worked nice with plenty of bite due to not being too cold.

[Spider]

Hi all,

 

I got a set of 4 pot metro brakes (i think) with the spacers to fit vented discs.

I have a 1996 SPI with the standard setup now.

 

I checked on Mini spares and they say that the drive flange - NAM6450F -   must be fitted to enable the vented discs to be used.

I read an old mechanical tips in an old mini magazine from keith calver that there is no need to fit these flanges if you have 8.4 inch discs as standard.

 

Whats correct? any ideas??

 

Probably not an answer or advice you are looking for here, but with the brakes you have, if I can suggest, a change I have tried and loved on one of my last Minis, was the fitting of Mini Spares 4 Pot Alloy Calipers. It possibly needed slightly more pressure on the pedal and the pedal travel was a little longer, but in terms of stopping, these were nothing short of brilliant. These were fitted up to standard solid Mini 8.4" Discs, on a standard Mini Hub.

[R32Egor]

Thanks all,

 

here is what I have -

 

 

 

 

It looks like a spacer has been added to allow vented discs to be fitted, and the adive here is saying remove the spacers and use normal non-vented discs and then there is no problems??

 

Last question - normal discs or grooved and  crossdrilled? and are the green stuff pads ok or too much?? (stage 1 right now and looking for stage 3 and 90 HP later).