Brakes

Post Reply
lozzaj
BMW Enthusiast
Posts: 2
Joined: 11 Sep 2013, 11:00
Car model: BMW 840 ci

Brakes

Post by lozzaj » 17 Sep 2013, 10:50

Hi all, just wondered if you could help me out, I have a BMW 840 ci (1999), I have found that the brakes are not very effective, the discs and pads are changed regularily but the brakes just dont seem too good, has anyone got any advice on what could make the brakes better? Thank you :D

User avatar
M60NJP
Site Owner
Posts: 23441
Joined: 12 Oct 2011, 13:22
Car model: 135i M Sport
Isetta 300
Location: Bucks
Location: Buckinghamshire
Contact:

Re: Brakes

Post by M60NJP » 17 Sep 2013, 11:00

Cars of that generation had (by today's standards) laughable small discs and calipers - so the expensive solution is a big brake kit, replacing the discs and calipers (checking they fit behind your existing wheels).

But before you go there have you checked the components of what you already have? Assuming there's no leaks, are the fibre hoses old such that pressure expands them? Braided hoses will make an improvement. Is the fluid in need of changing or maybe air in the system? Master cylinder fit and healthy?

Quite often in my experience is the matching of discs and pads and/or the brand - cheap pads and discs can be OK, but can mean we get what we pay for. I've never been a fan of (for example) Pagid pads on Brembo discs etc so mix/match can cause problems. I've never had much luck with EBC pads (particularly the low dust ones) although I know folk who've had no problem. Check for the obvious uneven wear, sticky calipers too!

I'd suggest starting at the hub, check what you've got and their condition and work back through the hoses, fluid, pipes to the master cylinder. Apologies if I'm telling you what you already know but don't jump in changing the fluid until you've checked the other components as you'll end up doing it again if you change most other parts!!

User avatar
Gus247
BMW Enthusiast
Posts: 11121
Joined: 17 Oct 2011, 14:24
Car model: '98 E36 323iSE Touring
'12 F31 330d Touring
Location: Reading, Berks.

Re: Brakes

Post by Gus247 » 17 Sep 2013, 11:23

I dont know how comparable the master cylinder is on 8's to the E36 3's but, for example, the E36 M3 had a bigger master cylinder than it's non-M equivalents.. swapping this over pushes more fluid and as such improves braking performance. I've changed the front discs and calipers on mine to those from an E46 330ci which has helped stopping power, however my pedal travel has increased everso slightly.... I have an M3 servo waiting to go on and this will resolve the pedal travel issue (which isnt really an issue!!....) :)
aka Andy

Image

BMW Forum UK

User avatar
Stratts
BMW Enthusiast
Posts: 1103
Joined: 02 Oct 2012, 13:00
Car model: E85 Z4 3.0i Auto
F20 116i 5Door for Mrs Stratts
Location: Upminster, Essex

Re: Brakes

Post by Stratts » 17 Sep 2013, 12:16

The front brakes on the E31 are notoriously weak for such a big, fast car. I think you will have the 4-pot Brembo units, have you had the discs off for inspection?, because most commonly the pistons get stuck in the caliper and you end up having only one or two pistons working. It's easy enough to spot in most cases as the disc will only be worn on 50% of the surface.

It is very common and you would need a refurb of the caliper.
2004 Z4 (E85) 3.0i Auto

Member of the number plate police (keep it legal!)
Photographer of people who can't park properly

lozzaj
BMW Enthusiast
Posts: 2
Joined: 11 Sep 2013, 11:00
Car model: BMW 840 ci

Re: Brakes

Post by lozzaj » 17 Sep 2013, 12:35

Thank you for your speedy responses, much appreciated.

Post Reply

Return to “Wheels | Brakes | Tyres”