hi all, been helping a friend upgrade to 4 pots but they have turned out to be pants compared to the standard 2 pots.
they've been bled 3 times now and the pedal still feels spungie, they are new discs and new pads.
its on a 98 uk turbo, any ideas what could be wrong cos its got me baffled now

 

Something is defo wrong as have done the same conversion twice and the 4 pots are a good deal better than the 2 pots, once bedded in.

Not being funny but, have you got the calipers on the correct sides, ie. bleed nipples at the top? It's been done before and will result in soft pedal as there is still air in the calipers.

 

yes mate, bleed nipples are on the top

 

How are you bleeding then?

Did you start with rear brakes first?

How much fluid did you lose when changing the calipers? and I am assuming that it is a standard UK MY98 with ABS?

 

the car was taken to a garage on thursday to be bled again and it came back just the same.
got the manual for the car and we've bled the brakes in the order the book says(front right, rear left, front left rear right).
and standard car with abs.

 

Oh, if a garage can't get it right then you have problems!!!!

In my experience of problems occurring after a change it is usually best to undo the change and try again. ie. refit the 2 pot calipers and then see if you can bleed the system then. That way you will know if the calipers are the problem or not. Unlikely I know but think it may be the best way to go in this situation

 

How much fluid was bled out each corner?

When I do it myself I aim for 400-500ml out each corner. 250ml out each corner is the minimum IMO.

 

What did the garage say when they gave it back?

 

Any news on this one? Just curious.

 

hey tony, cheers for all the ideas mate.
my mate who owns the car has bled them all again but slowly this time and seems to think it feels alot better, so still waitin to find the out come of that as yet.
just need to sort the problem out with my own motor now lol.
the joys of motoring ehh lol.

 

Do the 4 pot calipers bolt straight on,or do you need brackets.

 

lukey
yup straight swap bolt on (wheel/caliper clearance issue though)


tomo72
were the brakes pressure bled or pedal pumped?
i have had in the past on other cars issue with master cylinder seal going after bled by pumping brake pedal, if its pretty old may be needing replacement.

 

changed mine today from 2pots to 4pots and it was easy, you will need discs that match the calipers tho.

 

they were pedal pumped.

 

tomo you tried pumping the pedal so its hard and keep pressure on pedal see if it loses any pressure and pedal drops? (engine off)

its just this reminds me exactly of my old mk1 rs 2000 when i changed to 4 pots and pumping the pedal nearly full travel in the master cylinder damaged the seal and fluid was escaping past causing that spongy feel.

you do get a spongy feel from new pads/discs sometimes for a few miles til they bed in if you keep eye on fluid lvl and run it then see how they feel taking things steady obviously

 

bleed it out with engine running on a.b.s systems mate,this way the pumps working but only pump pedal half way.pedal will feel a bit spongy with new disc's and pads anyway till you get a few miles down road.:-)