Blimey, so 3 different pistons, 3-4 days each for between 21 and 36 grams each. There’s got to be a easier way to save that amount of weight??? Yes, I know, 0.01% here, 0.02% there. I get it that it all stacks up.
In my experience the seals fail due to age, heat and misuse for the most part. I’ve seen a few ally pistons corrode/pit, that then damage the seals, but this is after lots of use. Generally what kills them is when people don’t clean the pistons, and just force them back in during a pad change, dragging all the old pad/disc material and general road dirt between the seals and the pistons. Not seen any of the AP calipers with the stainless steel pistons yet, but would hope that AP have picked the right spec of stainless so it doesn’t corrode, or react with the calipers. I’ll be amazed if you have ‘zero maintenence’, especially as AP recommend checking the seals regularly.
When I change rubber lines to stainless braided ones, it makes a difference. This is changing something rubber - relatively soft - to braided lines - not quite as soft - but they’re still not stiffer than the pads/calipers. You have changed stainless steel - really hard - to titanium - really, really hard - both way harder than the pads and lines - soft/hard in this use refers to resistance to deflection before we discuss correct terminology. All you need for a piston is it to be stiffer than the least stiff bit.
Do AP not make titanium pistons for these calipers already? I see they now make titanium pistons with ceramic caps…
If you say so. I’d love to be able to spend as much time/money, redesigning every single component on a Lotus - and may have!! - but eventually people do tend to want to have a finished item to use. So you start to look at what the benefits are, compared to the cost and time implications, and then settle on a specification that is ‘good enough’ to do what is required, not break, not kill anyone, do exactly what it says it will do, over and over again. Otherwise you are constantly moving the goalposts when then next new widget comes out, budgets slip, deadlines slip and you end up with a nice advert for an unfinished project with some cool bits and pieces, and the whole experience leaves a bit of a sour taste.
Sadly there is no easier way, but there is a different way.
I realise that there are as many caliper pistons on a car as you choose to spec. No, I didn’t do a forensic analysis on brakes, I left that to AP, I’m pretty sure they know exactly what they are doing. I have however been messing around with the Elise platform since they came out in 96. Have built, spec’d, maintained, run in a race series, tracked and driven them a bit, I’ve a good idea of what makes them work, what doesn’t work so well, what’s necessary and what’s not always so necessary.
If you are 100% honest, do you think you could tell the difference between a caliper with stainless pistons and one with titanium? Pretty sure I couldn’t and pretty sure every car I have been involved with hasn’t had a problem with brake feel, despite not using them. Wait until you have your brake system all fitted, bleed and set up and take a look at how much your pedal box flexes when you lean on the pedal. You may get a little upset.
Maybe because there is a greater mismatch in thermal expansion between aluminium and titanium than aluminium and stainless steel; so once the calipers get hot the seal loading will reduce further with titanium pistons than with stainless ones, giving rise to a greater likelihood of fluid leakage?
My fave thread …
Love it
I’m gonna have just half a pint of ale with my dinner instead of a full pint …
Saving 250 grams and a quid .
How’s that for performance vs cost
Certainly the cheapest way to go faster in an Exige is personally move more and eat less, I couldn’t be bothered with that so made up for my bulk with carbon fiber and bigger brakes, seems like you are doing similar, I do love this build and watch with much excitement all the new bits you are doing. Be good to get them bolted on and test some of them
