Bigger Brakes

nicko500s
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Bigger Brakes

Post by nicko500s »

i am getting brake fade as you might expect with soild discs on my R45 with 17" straights, i have looked at getting 285mm MG set up as mentioned on this site but before i finally decide to do this does anyone have a better option?
or other ideas?
nicko500s
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Re: Bigger Brakes

Post by nicko500s »

well i went ahead and got the MG brake kit (285mm rover disks, pads and calipers) brand new and braded hose set as well, i fitted these today and bled the brakes renewing the fluid (we used about a litre) but the pedal is not as firm as i hoped, when braking the pedal has much more travel than with the old brakes and if you pump the pedal it firms up, but then has the excessive travel again straight away, i dont like it and im not sure why this would be, the calipers are handed, i put the L on the N/S and R on the O/S i used standard dot 4 fluid.

i bled the brakes O/S/R then N/S/R then O/S/F then N/S/F cos i was told to bleed the longest pipes first?
im not sure if the method i used is correct as it has ABS but all i did was opened and closed the bleed nipple as my friend worked the pedal, pausing in between pedal movements to properly close the bleed nipples. there was quite a bit of air bubbles in the pipe as we was bleeding as you would expect but these cleared and we was quite thourgh, using a litre of fluid.
it was very cold when we did this outside but i doubt that is the cause.
the brakes where actually quite good before we changed them so any thoughts greatly recieved :)
E_T_V
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Re: Bigger Brakes

Post by E_T_V »

Greater pedal travel is normal when fitting the 282mm discs/pads/calipers if they are from a ZR160/ZS180.

However make sure you are bleeding the brakes properly
If you have an assistant in the car you can give some instructions:

"Press" - assistant presses the brake pedal.
(you release nipple with a pipe attached to it directed into a pot - the pedal will go to the floor.)
(you tighten nipple back up)
"Release" - assistant releases pedal.
Then repeat 10-15 times then check fluid level in the reservoir topping up as necessary.

Once bubble free fluid is coming out of the caliper. Move to the diagonal opposite one and repeat. Before moving on to the other diagonal.
nicko500s
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Re: Bigger Brakes

Post by nicko500s »

thanks so much for the fast reply E T V. i guess the extra travel is due to the bigger pots?
its dissapointing to be honest i feel i have made them worse now, they where good brakes just so much fade with the solid disks.
from your description i bled them right just not diagonal, i think i will bleed them again that way and slower as we was doing it quite quickly.
is there a way to decrease the travel? is it cos the ZS160/ 180 has a bigger servo?
E_T_V
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Re: Bigger Brakes

Post by E_T_V »

Yes the bigger calipers mean more fluid to move which means more pedal travel. They should still be a huge improvement over the solid discs.

If you have drum rears then check the self adjusters are working as this also increases pedal travel.

I think the 160/180 have a bigger master cylinder to compensate for having to move more fluid.

Most people find the change acceptable but undesirable. You can fit a bigger master cylinder if you get desperate. I think one from a landrover fits but I'd need to do some digging.

If you use the 620Ti calipers modified to fit then the increase in pedal travel doesn't happen.
nicko500s
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Re: Bigger Brakes

Post by nicko500s »

If you are able to find out about the better master cylinder that would be great, I really dont like it as it is.
nicko500s
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Re: Bigger Brakes

Post by nicko500s »

i cant find any info on putting the landrover master cylinder on the 45 but there is some info on fitting the mg zs master cylinder to the std 45 as you said, but would this land rover one be even better?
E_T_V
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Re: Bigger Brakes

Post by E_T_V »

Here you go:
http://www.rovertech.net/forum/viewtopi ... der+master

It is a Discovery 300tdi master cylinder which needs modifications to fit. I.e. two new brake lines running as the exit ports are on the opposite side than the standard one.

I've not done it myself as I think the earlier R8 (wedge shaped 200's) already had the bigger master cylinder than the later R3 (bubble shaped) cars had.
nicko500s
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Re: Bigger Brakes

Post by nicko500s »

thanks E T V i looked at discos today but it looked like you would need the servo as well as the master cylinder mounting bolts are about 2 & 8 o clock position and the rover ones are different, plus as you say you need to sort the brake pipes so i decided to go with MGzs 180 master cylinder as that is a direct swap if you get the two brake lines off a doner car, i wasnt able to undo them from the abs unit so i will have to just bend mine.
nicko500s
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Re: Bigger Brakes

Post by nicko500s »

I made a mistake in the last post, the Rover bolts are 2 and 8 o clock (roughly) I cant remember what the disco ones are?
I fitted the used MG ZS 180 master cylinder and its not too hard to bend the existing brake pipes to fit although if you manage to get the MG pipes off it looks better.
Bled the brakes again, used another litre of fluid just to be sure and they are amazing, vertually no pedal travel at all!
strange cos they are only slighty bigger than the solid discs that where on there.

I cant see you would want or need the disco servo and master cylinder unless you are able to source even bigger discs and calipers? I bought massive motorsport brakes for my 800 vitesse years ago and they where hopeless, you had to stand on the pedal, i realise now it must have been due to the insufficient original master cylinder but no one seemed to know why at the time, and everyone was right, drilled disks do crack!
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