Hi ya guys,
Here is the dilema I\'ve been driving some other cars lately, and the brakes feel better, now don\'t get my wrong my Fd\'s breaks stop the car and they stop it well but they don\'t feel very good.
I\'ve been driving a lexus is200 sport recently and when I press the brakes they engage right at the top and it feels solid where as the rx7 just doesn\'t, when I press the brakes in the FD have to push quite a way before they engauge and the peddle never goes solid once its engaged, once the brakes are actually working I can still (with a bit of force) get the peddle to touch the floor. They feel a bit spongy, I\'d like somthing with a lot more "feel" to it, could someone with brakes they know are set up properly describe how they feel, I want to know if I have somthing I can cure or whether this is somthing I\'ve just got to get used to.
Alan
i find the brakes in modern cars very grabby and over-servoed compared to the fd. the fd is much more progressive and does require more pressure to get the same effect. having said this i have braided lines, and master cylinder brace, and upgraded pads so i doubt my brakes feel like the standard ones! i drove a new audi recently and nearly put myself throught the front window at the first junction i stopped at!
i really liked the progressive nature of them on track-i was able to brake hard without the abs engaging. having said that i boiled the fluid in a 20min sesssion so some uprated stuff is needed!
maybe you just need to adapt back to it once you have been in a newer car?
Quite possibly, I\'m just not sure they used to feel like this, I don\'t like the grabby feel of modern breaks but I like to feel that there is smothing solid that the peddle is attaced to rather than the spongy feeling I\'m getting.
I\'ve got Uprated Disks/Pads and braided lines on the back.
A
Could also be some air in the system or old fluid. Replace the cheap stuff before going mad on big setups!
Quote from: allstarukQuite possibly, I\'m just not sure they used to feel like this, I don\'t like the grabby feel of modern breaks but I like to feel that there is smothing solid that the peddle is attaced to rather than the spongy feeling I\'m getting.
I\'ve got Uprated Disks/Pads and braided lines on the back.
A
Hi A,
What pads / discs have you got ? also braided lines all round would help
Soft, and songy pedal will be fluid - when was it last chnaged or even bleed. Should be chnaged at least every 2 years. Forget pads and discs and braided hoses - get the fluid system bled and refreshed.If after doing that you still find the pedal is soft or spongy - or even after bleeding the pedal feels fine but then becomes soft again then you are looking at seals in the master cylinder allowing fluid to bleed back past the piston in the cylinder.
Quote from: allstarukHi ya guys,
Here is the dilema I\'ve been driving some other cars lately, and the brakes feel better, now don\'t get my wrong my Fd\'s breaks stop the car and they stop it well but they don\'t feel very good.
I\'ve been driving a lexus is200 sport recently and when I press the brakes they engage right at the top and it feels solid where as the rx7 just doesn\'t, when I press the brakes in the FD have to push quite a way before they engauge and the peddle never goes solid once its engaged, once the brakes are actually working I can still (with a bit of force) get the peddle to touch the floor. They feel a bit spongy, I\'d like somthing with a lot more "feel" to it, could someone with brakes they know are set up properly describe how they feel, I want to know if I have somthing I can cure or whether this is somthing I\'ve just got to get used to.
Alan
I changed the fluid at the begining of summer and bled the system then will do it again this week, what fluid do you guys recomend?
Clive, I\'ve got black diamond discks (drilled and grooved) and Hawk Hp pads standard lines on the front and braided on the rear.
So what does it feel like when you have a working system? Is there a definate point where it feels solid as you push?
A
Before I had the big brakes put on my car the brakes would do exactly as described! My standard brakes were awful....spongy non responsive, and absolutely no feel. You can do many different things with the brakes, remembering that the system is probably 10 years old compared to your Lexus that is only a couple of years old.
Changing the discs and pads is a good plan....the braided lines are great as they reduce the hydraulic flex in the pipe.
But I would suggest that you change the fluid firstly as it may have water in the fluid.
You can go for a big brake conversion....but then you get into difficulties with over braking....nothing worse than not being able to stop because your brakes are toooooooo good!
Dot 4 is the better fluid to go for....dont go for 5 as you will end up changing it more than you change you pants! Also you would need to change a lot of the seals in the brakes to cover the change.
Is the master cylinder ok?
Not sure on the master cyclinder I think its ok, not to sure how I would check , think my first port of call is to change the fluid, what make would anyone recomend?
A
AP551 is a good one to run, or if you really want to give her a good christmas pressie...ap600 Big difference in price though!
Quote from: allstarukI changed the fluid at the begining of summer and bled the system then will do it again this week, what fluid do you guys recomend?
Clive, I\'ve got black diamond discks (drilled and grooved) and Hawk Hp pads standard lines on the front and braided on the rear.
So what does it feel like when you have a working system? Is there a definate point where it feels solid as you push?
A
I suspect mine have a little air in the system as the first press has a little give in it, aftwr that they\'re pretty rock hard. I\'m running 5.1 race fluid and braided lines all round. BD front disks, HP+ rear, HT-10 front. The peddle feel is great (after the initial application) and I don\'t find it takes a huge ammount of pressure to get full force out of them.
Quote from: allstarukI changed the fluid at the begining of summer and bled the system then will do it again this week, what fluid do you guys recomend?
Clive, I\'ve got black diamond discks (drilled and grooved) and Hawk Hp pads standard lines on the front and braided on the rear.
So what does it feel like when you have a working system? Is there a definate point where it feels solid as you push?
A
With HP+ you should have VERY good initial bite, indeed I never recomend them these days for the front as they are very "grab n stop" with very little feel and they fade on the front.
Now I know what pads you are using I think you should maybe look at the pistons in the calipers to see if they are seized!
I\'ll get involved and see what I can find I think new fluid and a good bleed is my first port of call.
Is it possible to adjuct where they bite on the peddle?
A
Quote from: iaintI suspect mine have a little air in the system as the first press has a little give in it, aftwr that they\'re pretty rock hard. I\'m running 5.1 race fluid and braided lines all round. BD front disks, HP+ rear, HT-10 front. The peddle feel is great (after the initial application) and I don\'t find it takes a huge ammount of pressure to get full force out of them.
5.1 is Dot5......It is so hydroscopic that you run the risk of boiling your brakes, especially in a road car with the continual starting and stopping (yes I know thats what they are used for ;)) as that is when the moisture gets in. A quality Dot4 is far better....I dont even run it on my car I dont believe that the necessary frequency of changing the fluid out-ways that of the implied benefits.
Quote from: AtomicRex5.1 is Dot5.....
Sorry?
What does this mean?
Jon, have you got dot 5 and dot 5.1 mixed up?
Dot 5 is the silicone stuff and as you say horribly hydroscopic. Dot 5.1 can be mixed with dot 4, 3 and other fluids. Although as you say a good quality do4 can have better heat control properties than an average 5.1
If a pedal is very spongy as described but has new fluid and has beenb bled I still think it sounds like master cylinder seals allowing fluid to flow back when the pedla is pushed - it will give just that sort of sensation on the pedal - In fact, if you keep your foot on th epedal hard does it slow sink down to the floor - if it does than the problem is the master cylinder.
Tony
I thought that 5.1 was dot 5??? Or is it a "semi synthetic" type of fluid, which as you say can be mixed??? (I\'m still learning ;))
Id still stick to the ones I suggested up above.....and for the cost of it get some new seals on the master cylinder, cheaper than repairing the front of the car having gone into a wall!
ah, common mistake. 5.0 can\'t be mixed with any other fluid. 5.1 can be mixed with the other lower numbers. The products you mention are top notch as you say.
shalln\'t make the same mistake again!
Thank you oh racing guru! :p ;)
Ok I\'m going to change the fluid and bleed everything tomorrow then I\'ll let you guys know how its going but i suspect it being a crap master cylinder.
So what fluid should I be using(make and model please) and better still somwhere I can get it?
A
Make sure all your Caliper Pistons move smoothly.
Also have a real good look at the Rear calipers, Not sure if there the same as T2\'s but i went through a stage where mates where asking why there brakes Where Poor and after lots of messing it was the handbrake seal in the rear Calipers that was causing air to be drawn in, i only noticed becouse i pulled the Rubber Cover off the back to grease one up and it was full of Fluid.
If you phone Martin at Tweeks 01978 663 014 and ask for either
AP551 £4.52 per 500ml bottle
AP600 £11.66 per 500ml bottle
The AP551 will do fine, but depends on how you drive...if you use the brakes a lot down twisty roads and if you can spare the extra cash so soon after christmas then go for the AP600
Without wishing to teach grandmas to suck eggs....when you bleed the brakes make sure you start with the caliper furthest away from the master cylinder and work you way towards the one that is closest.
To save time on refurbishing the master cylinder I know either Carl or Gary have second hand ones! Could be worthwhile swapping it over....nothing worse than wasting the nice new brake fluid.
this is all interesting, and useful stuff, as i need to change my fluid asap after boiling it on track. how much do you need in total to do the change?
thanks for all the info guys!
Quote from: RAWthis is all interesting, and useful stuff, as i need to change my fluid asap after boiling it on track. how much do you need in total to do the change?
thanks for all the info guys!
Two bottles will be all you need, we have sold DOT 5.1 Lockheed ( AP )
non silicon fluid for the last few years for FD\'s at £5.63 + vat per bottle
http://www.mazdarotaryclub.com/forums/showthread.php?t=24058
hope this helps
Quote from: allstarukonce the brakes are actually working I can still (with a bit of force) get the peddle to touch the floor.
If you can get the brake pedal to touch the floor then either you have a lot of air in the system (need a bleed!) or your MC is fubar\'d.
Probably air in the system but if it\'s this bad it really is dangerous!!! I think the brakes on the FD are pretty good TBH, not much servo assit which is nice.
An easy way to check the MC is lightly press the brake pedal with the engine running, and just keep the same light pressure, if the pedal keeps sinking down slowly then the seal on the MC is letting fluid past so needs an overhaul.
GL!!!
Cheers lads will have a look today.
A
If the cap that goes on the MC is split, this would cause problems too?
Thinking about it mine\'s seen better days, can anyone confirm this?
confused about whether to get 4 or 5.1 now! i was going to buy 5.1 here:
http://www.tokyo-express.co.uk/engine/fluids.php (http://www.tokyo-express.co.uk/engine/fluids.php)
although Clive\'s prices seem good.
can anyone clear this up? i use my car for hard road driving but also track work. my standard stuff boiled after a 20min session.:3gears-lh
The 5.1 is just a semi synthetic version of Dot4 and can be mixed...Im sure Tony will correct me if im wrong!.... If you are boiling your brakes, then this can be because
the brake fluid you are using might as well be made from Tea
you are getting air in the sytem which leads to
you are getting water into the system.
Why compromise on the simplest of items? yes its another £20 but how much to replace a wing if you dont manage to stop?
Go for the AP600 it has a very good boiling point....and it will make you car go :Thumbsup!
If you really want to go the whole hog then get some Castrol SRF
http://www.raceparts-direct.com/products/fluids_and_lubricants_and_consumables.asp?group=Castrol
As you can see, not cheap at all! But it\'s a seriously good fluid, I think it\'d be nigh on impossible to boil that when it\'s fresh! And will mix with Dot4 and Dot5.1...
Ive always been perfectly happy with carstrol super dot 4 (SRF i think)...used it ony car at the nurburgrng and didnt get any fluid boiling...also used it at croft and snetterton with no issues....i was gonna use moutl rbf600 (i think thats what its called) but the castrol was readily available and not that dear either
Quote from: AtomicRex5.1 is Dot5......It is so hydroscopic that you run the risk of boiling your brakes, especially in a road car with the continual starting and stopping (yes I know thats what they are used for ;)) as that is when the moisture gets in. A quality Dot4 is far better....I dont even run it on my car I dont believe that the necessary frequency of changing the fluid out-ways that of the implied benefits.
Maybe the stuff in mine isn\'t 5.1 then - checking the label it\'s R600, not sure what the spec of that is!
Quote from: iaintMaybe the stuff in mine isn\'t 5.1 then - checking the label it\'s R600, not sure what the spec of that is!
Here you go Iain,
We have used this for the last few years and it exceeds all the above on this thread and is compatible with normal fluids.
http://www.aaoil.co.uk/frameset.cfm
Sunoco racing fuel? In your brakes? :-)
Quote from: MartinySunoco racing fuel? In your brakes? :-)
Sorry didn\'t realise the link wont copy properly !
Follow the link then go to "pitstop products" then onto "R 600+ Racing Brake Fluid
Product Information"