The curious case of the Atom 4 brakes

[plip1953]

https://www.questmead.co.uk/Categories/ ... CP2667-105

They are also sold in packs of 4, but last time I looked they were on back order.

So you need 4 packs / 16 springs for the whole car?

How hard are they to fit? Presume they need to dismantle the calliper?

Master cylinder wise this is the right one - 3/4” / 19mm?

https://www.competitionsupplies.com/til ... -cylinders

Yes, 16 springs, ie 1 per piston therefore 4 per caliper. Unless you already have experience messing about with brakes I would fairly strongly recommend you get someone who is to either do it for you or help you with it. Ideally, all four calipers need to be removed from the car as it's then must easier both to remove the pistons (although a reasonably high pressure air line will also be needed, and it can get pretty messy), insert the springs and then VERY CAREFULLY re-insert the pistons as they must go back in nice and square otherwise a main piston seal could easily be damaged. And even then it was surprisingly difficult to push the pistons in, even once started, which is something I'd not come across before. So some kind of mechanical piston spreader therefore comes in very handy.

And then of course you need to re-fit the calipers, re-attach the banjo bolts (ideally with new copper washers) and then bleed the system very thoroughly. At the end of the bleeding process clean away all traces of brake fluid (including in the top of the bleed valve using kitchen roll of loo paper rolled up and poked down the hole!!) and then get someone to press on the brake pedal as hard as they can and hold it for at least 30 secs. If the pedal sinks, even by a small amount, you have a leak somewhere. So always leave yourself access to all to bleed valves and banjos so you can make a visual inspection of everything right at the end.

A very handy tip when removing the calipers is to prop the brake pedal part way down. This stops fluid from the main reservoir flowing through the system and should mean minimal fluid loss at the open banjos.

As a guide it took four of us, albeit working at a leisurely pace and doing a few other bits and pieces along the way, around 6 hours!!!! Doing it a second time round I expect two people could do it in under 4 hours.

That is the correct master cylinder.

[robfitz]

Thank you.

Given that, I think I’ll just cough up and ask the factory to do it!

[Alistairbuchanan]

Thank you.

Given that, I think I’ll just cough up and ask the factory to do it!

If my brakes go back to what they were like pre service ill be p*ssed off….this should be a free factory service update


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[anx10us]

Thank you.

Given that, I think I’ll just cough up and ask the factory to do it!

If my brakes go back to what they were like pre service ill be p*ssed off….this should be a free factory service update


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Mine did exactly that, after service brake pedal was firm and there was no softness about it, a trackday at Bedford and back to how they were previously .. Will be interesting to see how yours go ..

[robfitz]

Thank you.

Given that, I think I’ll just cough up and ask the factory to do it!

If my brakes go back to what they were like pre service ill be p*ssed off….this should be a free factory service update


Sent from my iPhone using Tapatalk

They will do, let us know how you get on with that discussion

[speedmachine]

Thank you.

Given that, I think I’ll just cough up and ask the factory to do it!

If my brakes go back to what they were like pre service ill be p*ssed off….this should be a free factory service update


Sent from my iPhone using Tapatalk

This is what I was thinking. I am following this subjecy with great interest as I am totally surprised people are building custom made frames, add springs and so on to make a brand new system work as intended in the first place…

If all this is really necessary than it should be done to the yet to build cars (especially mine) and retrofitted to the allready build cars

I’m pretty confident I am not going to bring my brand new atom to a local brakeshop to tweak them…

[Alistairbuchanan]

Thank you.

Given that, I think I’ll just cough up and ask the factory to do it!

If my brakes go back to what they were like pre service ill be p*ssed off….this should be a free factory service update


Sent from my iPhone using Tapatalk

This is what I was thinking. I am following this subjecy with great interest as I am totally surprised people are building custom made frames, add springs and so on to make a brand new system work as intended in the first place…

If all this is really necessary than it should be done to the yet to build cars (especially mine) and retrofitted to the allready build cars

I’m pretty confident I am not going to bring my brand new atom to a local brakeshop to tweak them…

I dont wanna drive it now incase it reverts


Sent from my iPhone using Tapatalk

[speedmachine]

I think you are on to something…That might be the solution long term

[wasp]

Having spoken to the Factory, they aren't keen to do any work to a customer's car that they haven't tested themselves on their own car. I think that they will certainly try to the master cylinder at some point and possibly the springs too but haven't done so yet. Hopefully Henry will get into this very soon and find a solution but I do understand them being hesitant in bolting things to cars that they haven't tested.

Cheers,
Stu

[robfitz]

Steve said similar to me. I don’t sense any recognition that this is a problem or urgency to do anything about it though. Maybe I am reading that wrong….

[reg]

Having spoken to the Factory, they aren't keen to do any work to a customer's car that they haven't tested themselves on their own car. I think that they will certainly try to the master cylinder at some point and possibly the springs too but haven't done so yet. Hopefully Henry will get into this very soon and find a solution but I do understand them being hesitant in bolting things to cars that they haven't tested.

Cheers,
Stu

IIRC they already tested various master cylinder sizes. There seems significant pushback that it’s even an issue at the moment? It’s easier to have customers do the debugging…

[reg]

This is what I was thinking. I am following this subjecy with great interest as I am totally surprised people are building custom made frames, add springs and so on to make a brand new system work as intended in the first place…

Not as surprised as the same people who are building custom made frames, adding springs and so on to make a brand new system work as intended in the first place….

[reg]

insert the springs and then VERY CAREFULLY re-insert the pistons as they must go back in nice and square otherwise a main piston seal could easily be damaged. And even then it was surprisingly difficult to push the pistons in, even once started, which is something I'd not come across before.

That's odd. I still believe when it comes to calipers these are pretty terrible things. When you say difficult, difficult to keep square or something else? Good tip on the pedal.

[plip1953]

insert the springs and then VERY CAREFULLY re-insert the pistons as they must go back in nice and square otherwise a main piston seal could easily be damaged. And even then it was surprisingly difficult to push the pistons in, even once started, which is something I'd not come across before.

That's odd. I still believe when it comes to calipers these are pretty terrible things. When you say difficult, difficult to keep square or something else? Good tip on the pedal.

That wasn't a particularly good word to use. Making sure the pistons went back in nice and square takes care, but isn't difficult. But my point was that even once the piston was properly started on its journey it still takes a greater amount of force/pressure than I expected. Previously I've always managed to do it with finger pressure alone.

[robfitz]

When are you trying the car with the springs / new MC on track?