84 replies to this topic

[Hexxeh]

Spent many, many hours over the weekend fiddling around with this.

 

I set the ride height to 9.25" with me sat in the car and someone else measuring, and then started tweaking the camber/caster. Managed to get the caster to 3.5 with the camber at about 0.4-0.5. A bit less than I was aiming for, but I think probably within the bounds of the accuracy of how I'm measuring to be honest? Certainly a lot closer than it was, and the steering feels notably less heavy.

Checked the camber at the back and finding that one side was like 1 degree positive and the other 1 degree negative. Tried to adjust to get -0.5 deg both sides but I can't get them much closer than roughly zero on the driver side and -0.8 on the passenger side. The MS73 brackets I have on there don't seem to allow enough movement in the little holes used to set toe to get the position I actually need.

I could probably file them, but decided to order a set of the KAD brackets instead since these appear to be a different design that wouldn't have this problem. They also allow more fine adjustment of toe by the look of it, rather than just three predetermined positions.

I also rolled it out the garage and fired it up with the newly insulated and re-routed fuel hose - no joy, it still wants to die off periodically if I set the idle below 1k. I did chat to the chap who'll be tuning it on Friday and he thinks it may just be a mixture issue, so fingers crossed he can sort that out.

[Hexxeh]

Had the car over at RE Performance yesterday for the engine tune, ran into some ignition problems. I'd fitted Minispare's EVO electronic dizzy (https://www.minispar...-276-cam-profil). All was going fine for a bit, and then the car started to cut out and be difficult to start again. Ken did some diagnosis and suggested the dizzy was at fault, showing me some output on a scope he had connected up that didn't look as he expected.

 

Fortunately I'd brought a spare Powerspark dizzy with me that also had electronic ignition, so we swapped over the module and the coil (since the Powerspark one was for 3ohm and the minispares one for 0.9ohm) and it immediately cured the issue, fired up again immediately when the key was turned. Only problem I've got now is Minispares wants to swap the whole unit and I don't want to remove it and lose the ignition timing that Ken set up for me... I could leave it as is but I understand the 0.9ohm coil and module is supposed to provide a stronger spark and given I paid over £100 for the fancy unit I'd really rather have the benefit of it!

 

Finished the tune up, didn't get a power figure as the dyno wasn't producing a figure correctly apparently. Drove around a little bit and noticed the idle back up at 1100rpm, if I turn the car off and then turn it back on it starts at 800rpm but then eventually after maybe 30 seconds rises to 1100rpm. Ken fiddled around a bit more and it went down, but it's since gone back again, so I think something still isn't quite right. It does seem to drive pretty well though, I'm not familiar enough with Mini's to know if it's spot on but it certainly feels like a big improvement vs before.

 

I don't think he changed the dashpot oil, it still has the SU oil I filled it with I believe. I pulled the plugs today after the run over to the MOT garage while draining the oil (old oil smelt quite strongly of fuel, so wanted to get fresh in now it should be running right). Tips look okay, the base around it looks quite black though. Based on AC Dodd's videos it seems like perhaps it need to go a BP5ES rather than a BP6ES?

 

 

Still, it was in a shape where I could comfortably drive it the hours trip home, and it was great to finally drive the car more than just up and down the street at last!

 

Unfortunately, on the way home, I discovered a new problem. Under braking, the car pulls pretty badly to the left. Seems like some kind of brake issue?

 

The calipers are Mini Sport 7.9" vented, hoses are braided Goodridge, all the lines from the master cylinder are new (also braided hoses, rather than hard lines) and the t-piece and banjo bolt through it were new. I've tried to bleed them again, not getting any air bubbles out, but the problem persists.

I checked by removing the pads that the pistons on the right hand side caliper move freely: when applying the pedal without pads in, one piston moved (opposite the hose side), blocking that piston moved the one next to it, blocking that one moved one on the hose side and finally blocking that one moved the other on the hose side.

 

I popped down to an MOT garage to test it on the brake rollers and they didn't show me the numbers but said there was indeed an imbalance with the right side weaker, but that it wasn't unbalanced enough to fail the MOT. It sounds like it may have been somewhat close to the limit, though, so this does sound like it may be the problem.

 

I'm a little confused as to what to try or check next, can anyone share any advice?

Edited by Hexxeh, 09 August 2025 - 10:24 PM.

[Hexxeh]

Popped to another MOT place today to get the numbers for the brakes from the machine myself just to be sure: it's 137kg/f for the left and 94kg/f for the right, so significantly (46%) imbalanced, beyond what the first place suggested where I hadn't actually seen the figures.

 

I'm pretty confused because everything is new what could be wrong. Visually everything looks okay, the caliper pistons move freely, when bled no air comes out, pedal is nice and solid.

 

I've emailed Mini Sport to see what they suggest because it kinda feels like it has to be a faulty component somehow now, though I don't quite know how. They supplied everything involved (calipers, discs, pads, hoses) so hopefully they can help and don't just blame some other component.

[imack]

Does an 87 mini have diagonal spilt circuit brakes and that valve thing on the bulkhead (sorry, I've never progressed beyond single circuit minis!). If so, possibly a master cylinder issue. Are the rear brakes unbalanced as well, with the opposite rear corner to the fronts reading low?

[Hexxeh]

The car has the front/rear split type with two feeds out of the master cylinder, one for the front and one for the rear. The rears are connected via an adjustable limiter valve.

[stuart bowes]

When you say left / right is that OS or NS

 

first thing that occurred to me is a kink in the line that goes around the front of the subframe?  just thinking in terms of things that would only affect one side.  or a new but dodgy flex maybe

Edited by stuart bowes, 11 August 2025 - 02:18 PM.

[Hexxeh]

Sorry, left being NS and right being OS, ie as in left/right as you sit in the car.

 

The brake that's underperforming is the one fed from the t-piece on the subframe, so the hose that runs around the subframe is feeding the one that's working well.

[stuart bowes]

right o yeah that's why I was checking

 

that is odd then eh, any pipework issue before that would affect both presumably (but im no expert)

 

annoying that the flexies are handed so you can't even swap them over to see 

Edited by stuart bowes, 11 August 2025 - 02:22 PM.

[imack]

Have you tried swapping pads of disc from left to right and retry. Are minisport calipers handed and could be swapped over?
KAD ones are not handed, don't know about minisport.

[Hexxeh]

Have you tried swapping pads of disc from left to right and retry. Are minisport calipers handed and could be swapped over?
KAD ones are not handed, don't know about minisport.

 

The calipers are handed because of the single bleed nipple (putting them on the correct side puts the bleed nipple at the top).

 

I haven't tried swapping discs since that'd mean undoing and re-torquing up the hub nut and I'm not sure where I've put the special washer you're supposed to use to seat those properly. I wasn't really sure what could be wrong with the disc that you couldn't tell just by looking at it - it could be contaminated I guess but I did clean everything with brake cleaner when fitting.

 

I suppose swapping the pads would be easy enough though, could give that a go.

[sonscar]

A brake pressure tester screwed in the bleed nipple could show any difference in line fluid pressure?watch the disc,pad,caliper when operating the brakes for movement or catching.Just thoughts,Steve..

[Hexxeh]

A brake pressure tester screwed in the bleed nipple could show any difference in line fluid pressure?watch the disc,pad,caliper when operating the brakes for movement or catching.Just thoughts,Steve..

 

Had thought about that, but a quick look online showed even the cheapest ones are over £100 and I don't know anyone locally who has one. It would be a nice though since it'd rule out the hose if the pressures were matching both sides I guess.

[stuart bowes]

if pads dont make a difference I suppose you could pull out the big bolt from the banjo, have a look at that and check the hole through the middle is machined properly and not slightly blocked or anything, check the connection to the flex at the same time

 

bit of a faff to take apart though I know :/

Edited by stuart bowes, 11 August 2025 - 06:41 PM.

[colinf1]

Is it using all braided hoses rather than hard lines with braided to calipers that's causing the issue? It's maybe finding a weak spot on the diagonal hose that's reducing pressure to that caliper?

[timmy850]

Have you bedded in the new pads and discs properly?

New calipers can also have slightly sticky pistons that haven’t found their ideal resting position yet and perhaps one is taking more travel to contact the disc. You should be able to inspect the pads & see if they have much wiggle room at rest, and then observe how they contact the disc when someone presses the pedal down