Mazda Rotary Club

General => General Technical => Wheels & Tyres, Suspension & Brakes => Topic started by: Initial-D on January 30, 2007, 11:52:18 PM

Title: Brake bias??
Post by: Initial-D on January 30, 2007, 11:52:18 PM
I\'m having the ABS unit from my FD removed but wondered wheather the brake lines being different lenghs e.g. front right shorter than the left, would create an uneven brake bias between them?:xconfused
Title: Brake bias??
Post by: Martiny on January 31, 2007, 06:58:00 AM
I doubt it, they are unequal lengths at the back.
Title: Brake bias??
Post by: clive on January 31, 2007, 08:24:58 AM
Quote from: Initial-DI\'m having the ABS unit from my FD removed but wondered wheather the brake lines being different lenghs e.g. front right shorter than the left, would create an uneven brake bias between them?:xconfused

Hi Ben,

Please only Only trust this job to someone who is very competent because after removing the ABS they will need to trace the pipes directly from the master cylinder to the  brakes individually and then repipe accordingly to ensure that the correct halfs of the master cylinder are operating the correct ends of the car.

Hope this helps.
Title: Brake bias??
Post by: antnicuk on January 31, 2007, 08:50:46 AM
i am in the process of doing this to my car and also fitting a bias valve to compensate for the bigger front brakes.

I wouldnt have though length would matter,  Mazda ones are no where near the same length, the passenger side front wheel is very close to the abs unit but the drivers side front is much further away.
Title: Brake bias??
Post by: TonyC on January 31, 2007, 09:09:58 AM
The ABS pumps does have the inlet/outlets marked as Rear, front left and front right so it should be clear which pipes need plumbing where once it has been removed. Remember to plump the bia valve on the line to the rear, not between the front left and right :driving
Title: Brake bias??
Post by: Initial-D on January 31, 2007, 09:44:08 AM
Thanks for the concern Clive!

Thats good news then, we thought it probably made no difference if they were different lengths.

Ah bias valve, nearly forgot to mention that to the guy, cheers Tony. Was thinking AP unless you know a good alternative? Anyone know the going price for a 929 master cylinder? - might well do that at the same time if its not a fortune.
Title: Brake bias??
Post by: DRAGON on January 31, 2007, 10:26:02 AM
This pic maybe some help, I also put a line lock in this set-up, the Bias controll is in the cabin.
Title: Brake bias??
Post by: antnicuk on January 31, 2007, 12:23:43 PM
very neat, i wish i had the patience
Title: Brake bias??
Post by: TonyC on January 31, 2007, 12:42:58 PM
Quote from: Initial-DThanks for the concern Clive!

Thats good news then, we thought it probably made no difference if they were different lengths.

Ah bias valve, nearly forgot to mention that to the guy, cheers Tony. Was thinking AP unless you know a good alternative? Anyone know the going price for a 929 master cylinder? - might well do that at the same time if its not a fortune.

AP\'s are good, although I\'ve gone for a wheeled one, rather than the classic AP lever. There should be more adjustment in the wheel type. There are a quite a few knocking around on ebay fo rmuch less than Demon Tweeks or similar. Rally design are quite well priced as well if you are after a supplier.I\'ve not done any work on my car for a week as I\'ve been ill, but getting back into it tonight - can;t touch the brakes though as it is due to go off to the paint shop monday. Will be able to give more pictures/info in a few weeks as that is going to be part of the next batch of jobs.

(Is there a reason the strut brace isn\'t bolted on in the picture?)
Title: Brake bias??
Post by: antnicuk on January 31, 2007, 02:05:26 PM
i have a willwood one which has a knob..........
Title: Brake bias??
Post by: AtomicRex on January 31, 2007, 04:25:44 PM
Relying on a brake bias isn\'t always the best move as it isn\'t really doing the best job....if you can...and have the time....

Ive redone the master cylinders on mine and fitted a balance bar between the two.  This is a lot safer than just turning on or off the rear brakes, as what you are not doing is balancing the brakes
Title: Brake bias??
Post by: Ed_RX7 on January 31, 2007, 06:24:00 PM
ive got a willwood brake bias on mine..... also have a 929 cylinder...ben you should be able to pick one up for about 90 quid..........trust me well worth the money if you have a big brake upgrade....also account for making up new brake lines as on the 929 the connection is on the other side....
Title: Brake bias??
Post by: antnicuk on January 31, 2007, 07:35:18 PM
Can you explain a bit more about this 929 cylinder?,   is this a Mazda 929, if there is such a thing.
Title: Brake bias??
Post by: Ed_RX7 on January 31, 2007, 08:40:17 PM
ANT, the cylinder is off a mazda 929...think they only made them in america or oz...cant remember which...the 929 cylinder is about i nch bigger than the stock cylinder ...thus greater force to push the fluid round...thinking about it got mine for £75.........just can t remeber where i got it from now. but if i remember i\'ll pm ya.
 
its basically what feed use  and badge up as theirs IMO...but the price!!!!!!!...see reworx website.
Title: Brake bias??
Post by: Initial-D on January 31, 2007, 11:08:27 PM
Well if you remember that\'d be great. I\'ve had a look and there seem to be two types of the 929, ones for cars ABS and another without? Surely they\'d be the same??

I\'m still using standard FD calipers and rotors but it\'s basically to make best use of what I have until I can get some really good brakes. Whilst the cars having all bits on and off it seemes like a good plan to simplify and remove all the bits not needed. The stock brakes have been good to me on track with no fade as yet! But the ABS was coming in too soon so I\'ve made the decision to pull it.

Big thanks to all the posts - most useful!
Title: Brake bias??
Post by: Ed_RX7 on February 01, 2007, 02:28:40 PM
think i got the abs one.
Title: Brake bias??
Post by: Initial-D on February 02, 2007, 05:12:26 PM
Was going to get this brake propotioning valve, Just fancied the lever over the screw type!

http://www.demon-tweeks.co.uk/products/ProductDetail.asp?cls=MSPORT&pcode=GDR90-1000
Title: Brake bias??
Post by: Ed_RX7 on February 03, 2007, 08:13:37 AM
if it does the job...go for it.