Legacyb4-Dan

iTrader: (1)

I have the 4 pot CP6600 calipers and godspeed two piece disc, i got the replacement rotors onto my old disc bells(pain in the ***!) and i was going to repalce the seals too on the calipers but rounded the wear plate bolts so that was the end of that. I just threw the old pads back in with new discs. I bled the front calipers only and as a result the caliper body was actually rubbing on the disc. Im hoping its just a bleeding issue and once i get the correct sequence all pistons will work right and nothing will rub!

There is two bleed valves on the fronts and only one on the rears. Do i pump the brakes a few times after each time i bleed the caliper/caliper side or only when all have been bled.

Thanks
Dan

ditchmyster

iTrader: (7)

Bleed the furthest away from the servo first, so opposite side of the car rear first, then the next furthest etc until you get to the nearest to the servo and do that one last, if that makes sense.

Don't keep pumping the brakes, best way is to get someone to help.

Open bleed nipple, press brake pedal to the floor and hold it there, close bleed nipple, let pedal up, and repeat until no air in that line. helps if you have a bit of clear hose on the nipple so you can see when there is no air bubbles.

Don't for get to keep topping the reservoir up otherwise you'll re-introduce air into the system.

P.s where did you get the rotors and do you have a part number? I have the same set up and will no doubt be needing new rotors sometime.

Don Clark

If the caliper BODY is rubbing on the disc it would seem that the caliper requires re-shimming to suit the new disc. No amount of bleeding will fix that problem.

When new, AP calipers are supplied with spacer washers for this exact problem.


As for which of the two nipples on the caliper to bleed first - do the outside first then the inside.

2. Bleeding procedure
2.1. Connect a bleed bottle and tube to each caliper bleed screw and fill the reservoir, leaving the reservoir cap off. Open the
bleed screws of each caliper in turn to allow the system to gravity fill, until clean fluid can be seen in each bleed tube. Check
that the fluid level in the reservoir does not fall below the outlet opening. Close all bleed screws.
2.2. Where dual master cylinders are used, bleed one front and one rear caliper together. For calipers with two bleed screws,
bleed the outer side of the caliper first, followed by the inner side.
2.3. Never bleed the system by pumping the pedal until it is firm followed by opening the bleed screws. If there is air in the
system, this procedure will aerate the fluid, making removal more difficult.
2.4. Air in the master cylinder primary and secondary chambers should escape to the reservoir via the feed line when the brake
is off. If there are any restrictions in the feed line or reservoir connection that prevents air from escaping, air that remains in
the feed line will be drawn back into the cylinder on the recuperation stroke. To minimise the restriction, dash 4 hose and
fittings should be used for the feed line, particularly if the reservoir outlet is close to the cylinder inlet.
2.5. Open the outer bleed screw of a front and rear caliper and slowly depress the pedal to avoid fluid aeration, using the full
master cylinder stroke. Close the bleed screws and let the pedal return fully to its original position to allow the master
cylinder to recuperate fresh fluid from the reservoir. Do not allow the pedal to snap back, use a controlled rate of return. Rest
for 5 seconds to allow the master cylinder to re-fill. Top up the reservoir as required. Repeat until no air is visible in the bleed
tube. Depending on brake hose runs, a clear tube should be achieved within 3-5 strokes.
2.6. Repeat section 2.5 for the inner bleed screws of the front and rear caliper until no air is visible in the bleed tube.
2.7. Repeat sections 2.5 & 2.6 on the other side of the car.
2.8. Repeat sections 2.5, 2.6 & 2.7 if pedal travel is not satisfactory.
2.9. If the pedal is not firm after repeating the procedure, there must still be air in the system and an alternative procedure, backbleeding,
is recommended. Using this method, a large volume of fluid and any air that is trapped in the system is returned to
the reservoir via the master cylinder inlet port.
2.10. Fit thin pads, or preferably just pad backplates, to each caliper and slowly pump the pedal so that caliper pistons move
forward to contact the pads. Working on one caliper at a time, squeeze the pistons back into the caliper, displacing fluid to
the reservoir. The reservoir will fill with displaced fluid so it must be emptied to prevent it from overflowing. Repeat the
procedure for each caliper and re-fit the original pads before pressurising the system with the brake pedal.
2.11. After bleeding, check the complete system for leaks before driving the car.
2.12. Recommended bleed screw torque (do not over-tighten bleed screws):
Cold Hot
0.375” UNF & M10 threads: 14Nm 18Nm
2.13. The aim when bleeding is to achieve a firm pedal that holds its position under a sustained pedal load. Re-bleeding the
brakes after some running can further improve the pedal.
2.14. IMPORTANT - When the system is fully bled, the threaded rod of the balance bar should be at right angles to the master
cylinder push rods when the normal maximum pedal load is applied.

Legacyb4-Dan

iTrader: (1)

Thanks for the reply guys. The problem is these are replacement rotors for what I already had on there. They are two piece godspeed discs . the calipers have the spacers fitted already same as before.

So I'm hoping it's just a bleeding sequence issue

TECHNOPUG

iTrader: (1)

I fitted AP 4 pot fronts (reconned by Godspeed with their 2 piece discs).

I found that the "furthest to nearest" method left a lot of trapped air. I was replacing all my brake fluid at the time.

I bled them again and this time used the sequence as prescibed by Subaru. Impreza has a diagonal brake system, using 2 circuits - the calipers you fit are irrelevant. Bleed in the following order:

FR
RL
RR
FL

Most of my air was trapped in the secondary circuit, which is the FR-RL.

If the actual caliper body is contacting the discs, I don't think that bleeding will help!

Either they aren't fitted properly or the replacement discs are bigger than the original that the kit (caliper mounting kit) was designed for.

Where exactly is it rubbing? On the pad side of the disc against the caliper body (struggling to imagine this) or the rim of the disc on the inside of the caliper (not where the pads are fitted)?

If it's the latter, your discs are bigger than original. Easiest fix is to get some washers and just space the caliper out the required distance.

Legacyb4-Dan

iTrader: (1)

SO i couldn't figure this out the caliper body rubs off the discs when turning. I had to leave it into my mechanic and he said that it seems like those discs are too thick for the AP CP6600 calipers. they are 330 x30.3mm~ but definitely seem too thick, also he said there is very little clearance with the tie rod end and the discs also. Think i need to talk to Godspeed and see why the tolerances are so close and possible solution

TECHNOPUG

iTrader: (1)

AP CP6600 are definitely for 330*30mm discs. Have you measured the discs - are they 30mm?

I presume that only one side of the disc is rubbing against the caliper, as if it was both, you'd never be able to fit them?

What bells are you using? If the bells are wrong, it will put the disc in the wrong place in relation to the caliper. Or the mounts are wrong and the caliper is in the wrong place in relation to the disc.....

If the disc is only rubbing on one side of the caliper, you can just use some washers on the mounst to centre the disc, one way or another.

Are they definitely CP6600 calipers?

My money is on the bells though, if your mech thinks the discs are in the wrong place.

Don Clark

https://www.apracing.com/product_det...30mm_disc.aspx

https://www.apracing.com/drawings/cp6600_1cd.pdf

Legacyb4-Dan

iTrader: (1)

So yes they are cp6600 calipers. And replacement discs were supplied from godspeed as I bought the kit from them originally. My mechanic thinks it is down to the fact that the Bell don't suit the new replacement discs and there is 17mm on side and 19mm the other side approx so thats the issue he thinks. 2mm can be shaved off the disc to make it work but I'm not gonna do that. So I guess I need to find out from godspeed if there bell design/ offset has changed over the years as something doesn't line up now. I'll take the whole setup off as soon as I get some spares and probably send it all back to them