Brake pedal travel

[KevD]

Picked the car up after nearly 4 weeks of garage time. It's had calipers refurbished and new hoses and pads fitted after one of the calipers were sticking which damaged the hose and pad on that side apparently. It then got a new master brake cylinder as they couldn't get the old one to bleed up apparently.

It's now back with a huge amount of pedal travel before the brakes start working- probably 70% before any reasonable braking performance and even then it doesn't stop well.

It's heading back to the garage again Monday, they are planning to rebleed but I'm starting to lose confidence- is it a bleeding issue or are the replacement pads just not up to the job? Previously I had mintex 1144s but it's standard spec mintex ones on now.

[tut]

Pads have nothing to do with pedal travel, just stopping ability.

It has new fluid in and the callipers have been refurbished, so it should be down to proper bleeding to get rid of all the air, or there is an air bleed somewhere.

tut

[KevD]

Hopefully a quick fix then, cheers I'll persevere with current garage then take it over to Edinburgh if it doesn't work out. They've been good and only charged me a few hours labour for what's taken a lot more but it's still not right!

[tenkfeet]

Its been a long time but you have to invert the front calipers to bleed properly. Some one in the know I am sure will clarify that.

[robin]

You don't *have* to invert the calipers, but often it is the least painful way to get the air out.

Note, this applies to the front calipers ONLY. It's because the outer cylinder is connected to the inner by a little transfer pipe and this allows airlocks to develop; turning it upside down allows the air to jiggle through.

Kev - if you pull on the handbrake (while stationary, obvz) does the pedal go hard while the handbrake is applied? If so the problem is with the rear calipers. If you operate the handbrake and foot break repeatedly you might find it just starts to work properly! The reason for this is that the piston in the rear calipers has a ratchet mechanism which takes up any wear in the pads to keep the handbrake operating at a reasonable travel; the ratchet has to be reset during pad change (which they will have done), but will take quite a few handbrake cycles to pump back up again to normal. Whilst the ratchet is reset the foot brake travel can be very long.

Alternately, if you jump up and down on the pedal really quickly (river dance stylee), does it get (and stay) hard until you release the pressure on the pedal at which point it goes soft again? In that case you've got air in the system - my money would be the corner(s) that have had caliper refurb.

I find pumping the pedal up (to compress the air) between each bleeding stroke of the pedal normally gets all the air out, even air stuck in the top of the front caliper - but if they cannot get the air out then they need to remove the front calipers, rotate them around so that the transfer pipe is up, wedge something between the pads (watch your fingers - the calipers will easily make a mess of a finger stuck in there), operate the brake pedal a few times to force the air to accumulate in the transfer pipe. Now rotate the caliper to the horizontal with the outer up and the inner down; operate foot brake again. Imagine you're chasing the bubble in a spirit level around from the top of the inner piston to the top of the outer piston - I am sure you can see what's happening. Finally refit the caliper as normal and bleed - the air should have all collected in the outer chamber and should be ready to bleed out.

One other point - I have found in the past that bleed pipes can be a poor fit for the nipples and that the nipples can bleed back air through the threads. So I have always taken the manual 2-person bleed approach - one person operates the pedal, the other the bleed nipple with a spanner. Sequence should be nipple closed, pedal up, nipple open, pedal down, nipple closed, pedal up, ... For maximum effect it can help to get the pedal hard (river dance) before opening the nipple - this compresses the air and can help force it around awkward bends.

Cheers,
Robin

[tenkfeet]

A helpful video.https://youtu.be/WSYdOidSqjU

[campbell]

I have found that Craig's crew will always get the pedal well hard. Fnar.

With one exception, for which I believe the apprentice got a hot oil cocktail force fed, Fast n Furious stylee.

[KevD]

Dreaming of a hard pedal...

Handbrake trick didn't make a difference so looks like its fronts ( which are the refurbed) . I think the garage have been trying to use a pressure bleeder. I'll mention they might be better with a manual two person approach pumping brakes as per cycle detailed above and offer to cover their time. Looking forward to getting her back now the sunshine is gone.

[campbell]

If your garage can't get this right, Kev, then they perhaps shouldn't be your garage.

It's an elementary procedure for a true motor engineer, and safety related at that.

Fingers crossed though, as if they are your garage of choice it's always nicer not to have to change

[Dominic]

If your garage can't get this right, Kev, then they perhaps shouldn't be your garage.

It's an elementary procedure for a true motor engineer, and safety related at that.

Fingers crossed though, as if they are your garage of choice it's always nicer not to have to change

Was thinking the same. If I can manage it, surely a garage should be able to.

[woody]

Bleeding S1 brakes after they've had the circuit opened is, in my many experiences of it, a monumental PITA. Without knowing the various elise eccentricities & how to over come them (assuming this is a garage not used to elises) I can see why they may have had an issue. Suspect the lack of servo may have confused them too with a soggy pedal feeling more like a normal cars?

[campbell]

All the more cause to identify an experienced Lotus specialist, then.

This'll be why my local (otherwise excellent) independent declined to touch my, or any other, Elise some years back.

[Ferg]

Nowt wrong with using pressure bleeders.

[2F45T4U]

Another way is to bleed best you can, remove the pads and caliper, pump the pedal gently to extend the pistons to almost full travel, then lever them back in. This displaces the air from the caliper back up to the reservoir. Do this a couple times, rebleed via the nipple.

There is more accumulation of fluid in the caliper than the volume of air trapped on the inboard cylinder and the pipework back to the MC. So it normally displaces it.

[KevD]

It's a good garage that's done us well in the past, hopefully they sort it by wednesday.. If not then I'll head to edinburgh for craig to fix it - if I'd known a month ago eh was up in business I'd have taken it there for the service and wheel bearing which has turned into this saga! Thanks for all the advice - keen to keep it in professional hands if I can!