Lude Generation

I have another track day booked for my local track at Abingdon next month, and decided I need to do something about the lack of pedal feel in my brake setup. This is one of the last things I don't like about the car! Its not a big braking circuit and you don't even get out of 4th gear, but I already know the feel will annoy me.

I'm running:

DS2500 pads front and rear. These have seen multiple track days but never faded. Only about half worn thickness.
MTEC drilled and grooved front and rear (300mm ATR fronts). These have seen multiple trackdays and are not worn out at all in overall thickness at all.
ATR calipers (freshly rebuilt again with new pistons/seals/pins/grease/etc since last track day).
not so many years old remanned rear calipers as i know they like to seize up (handbrake works fine and not seized, also new pins/grease etc).
RBF600 fluid is changed out pretty often.
1 way bleed valves on each caliper.

The pedal feel can only be described as body lemonade poor. This is not to be mistaken with poor performing brakes. They are just too vague. the first inch of pedal does very little. I can't remember if they have always been this un-responsive, as the ATR setup has been on for years.

On track, I find I have to knock the pads back before the braking zone to get a better feel. I'm not going to replace all 4 wheel bearings on a whim , as I have no reason to believe this is the cause. At no point on the last track day (Bedford full size circuit), i was doing multiple ~10 laps stints, and the brakes were no where near overheating - the ATR setup drilled and grooved dissipates the heat very well, and prevents me having to step up to more aggressive pads or worry about heat range. Perhaps if the feel was better, I would be braking harder. Compared to a trip in a DC2, i was only braking about 65% force compared to that. Prelude is a much heavier car but its still not quite able to capitalise on the brake force that should be available. Likewise, DC5 has immense feel from the brembo 4pots when I drove it last, these were aftermarket pads/discs also (not cheap). Even when i drove a bog standard 2.2vti (free ranj eggs) , the stock setup felt nicer, so i have some issue for sure.

Very infrequently, just on normal road journeys, there can be a marked improvement in my pedal feel for no reason. It tends to last the entire journey, and is gone again the next. This is the most troubling aspect as it seems odd to have variability in the setup. During such a journey (this is maybe 1 in 50+ journeys), I can really feel the brakes and the feel is great and solid. Much less pedal travel/effort. Alas, i'm at a loss as to what is causing it or why it suddenly feels better! If they were always in the better mode - i could live with it. This does not seem related to the servo function, the pedal effort is always the same.

So my thoughts/questions:

1) refresh discs and pads for the same - they are old and the front discs have a slight unevenness to the wear (about 1cm from in from the outside edge, there is a band wear deeper than the rest, only slight not especially worried by it).

2) Braided hoses - 21 year old hoses can't be good for anything especially with the track abuse. Hard to test and verify without removing them, so perhaps worth replacing regardless? about 70 quid. Don't like the idea of removing them from the metal brake line though - trouble there for sure...

3) ATR master cylinder? Not sure if anyone has tried this mod. Hard to confirm on part numbers, but i think the 5th gen prelude is 15/16ths inch bore, and ATR is 1inch bore. Does a 1/15th (6%) increase really make much of a difference? With the current 'issue' i feel like i need 25% better travel/response. I've never found the need to rebuild a brake master cylinder before , my experience is only of clutch master cylilnders, which tend to just fail in entirety. Anyone ever rebuilt the standard brake one to resolve any feel issues?

4) I always suspect the rear calipers - i hate the combined piston/handbrake mech, it always goes wrong and perhaps the remanned calipers are never as good as new. Anyone ever tried clamping up both rear brake pipes and going for a drive to confirm? I have found that adjusting handbrake tension can greatly affect the feel/slack of the system as a whole. It shouldnt happen because of the adjustment, but i never trust it. The hand brake works absolutely fine, and has no trouble (other than great arm effort) locking up the rear wheels as i found out (quite surprisingly i might add!). I believe it is correctly adjusted (and doesn't explain the variable occasional good journey i have).

5) Some other component or issue? Brake bias valve faulty? ABS module? bleeding method issue? Any other ideas?

Very recent MOT test had no advisories, and the following brake balance information (sun vic 3000 atl machine).

Front:
Wheel drag Left =13kg/f , Right 14kg/f
Brake force left = 320kg/f , right 329kg/f
axel weight 861kg

Rear:
Wheel drag Left =10kg/f , Right 11kg/f
Brake force left = 129kg/f , right 123kg/f
axel weight 522kg

handbrake:
Brake force left = 164kg/f , right 154kg/f


total weight 1,383kg! (half tank of petrol, space save spare, not much else in the car!) Motegi kit + fogs doesn't add that much, perhaps the occupant was large. Still heavier than i thought...

To me, they seem pretty in balance left/right , which is good given the recent refurbishment. I'm leaning towards a hydraulic issue, any ideas welcome.

I would always say braided lines. The difference is night and day. Other than that, just a general clean up and lube up combined with a fluid change.

That would basically put you up to the same set up I had on my 5th gen and other than the juddering/noise of the grooves in the discs, they were spot on.

Abs = 1 inch
Non abs = 15/16th.

If your non abs upgrade the master cylinder.

It's the master cylinder that's the issue. I have the same feel with atr brakes and I have the same feel with the KB1 legend brakes. The brake pedal is very progressive and linear. Completely the opposite to me to s660 and van. Takes getting used to but the brakes are superb. Just not much brakes for the 1st inch of braking.

Changing the master cylinder will sort this but I have not researched to what just yet.

Thanks for the replies. I don't find the noise from the discs too bad. If for some reason i have the back seats down, radio off, i can hear the rears under braking, but not much.

If the same setup for you felt spot on, then i'm leaning towards master cylinder. It is odd that just occasionally it will feel perfectly firm, but most of the time be unsatisfactory. Perhaps there is an issue with the pedal linkage, maybe i should have a look down there too (remind me to grease the clutch pedal thats started squeaking aswell!).

Id have hoped a problem with the lines would leave some kind of visible deformation, there certainly is no leakage (fluid has only dropped a little as a result of pads wearing down).

Car is UKDM 2.2VTi with ABS as standard. Not many of the parts listings make mention of this, so still hard to be sure. Some 4th gens are listed at 15/16ths , i guess because very early examples might not have abs? not sure when it became mandatory?

lings don't list a rebuild kit as such, but both pistons and seals add up to a pretty penny

RattyMcClelland wrote: ↑

Sun Sep 06, 2020 4:26 pm

It's the master cylinder that's the issue. I have the same feel with atr brakes and I have the same feel with the KB1 legend brakes. The brake pedal is very progressive and linear. Completely the opposite to me to s660 and van. Takes getting used to but the brakes are superb. Just not much brakes for the 1st inch of braking.

Changing the master cylinder will sort this but I have not researched to what just yet.

The weird part is this doesn't explain the odd trip where the pedal suddenly is firm as fook, and i can really hammer the brakes and they are great. Perhaps that was an occasion where the rears were frozen (i did have 1 stuck rear guide pin recently which led to the refresh - not driven much since but i have not had the good 'feel' since then actually).

bloody cars, makes you want to buy a new one at times...

Yeah, I would tend to agree then, as mine were solid no matter the climate or driving style. The fronts were rebuilt before fitting with new sliding pins. The rears weren't, but slider pins and handbrake mechanism were freely moving.

Just had a quick scout on ebay and you can get a replacement (non-genuine) master cylinder for around £75.

Seems to be a lot of parts numbers , and not many parts!

Lings honda and https://www.parts-honda.uk/ both list 46100-s30-951 as the master cylinder.

not available on lings or parts honda. However, searching for the part number on the latter, shows a replacement part number 46100-s30-952

Searching around for that online i don't find much, except a different part number!

buycarparts.co.uk seems to amalgamate many parts catalogues along with the OE partnumbers and snippets of detail which help piece together the whole picture , and can search for similar part numbers. They list the equiv part number as 46100-s30-a51 (not -951). Don't fancy ordering one for it to be wrong (and the pictures are normally stock photos). https://www.buycarparts.co.uk/search?ke ... 00-s30-a51 all out of stock along with A52 , but seems to match up with japan parts own part number pf446 https://www.ebay.co.uk/itm/JAPANPARTS-N ... SwyZhfN3fL

maybe worth a punt - perhaps cheaper to just buy a 15/16th and 1inch rebuild kit from ebay?

My setup.
KB1 4 pot front calipers
328mm brembo discs
dixcel type z pads
Goodridge brake lines all round
Motul RBF600 fluid
pHresh Rebuilt OEM rear calipers,
OEM rear discs
EBC redstuff rear pads

Both ATR setup and legend KB1 setup "feel" the same.
Very progressive pedal feel. Minor braking = minor pedal travel, epic braking = epic brake travel.

But very consistent ALL THE TIME.

BUT s660 on OEM brakes and VW t6 on 4 pot Audi rs3 brembos the pedal feel is very different but the same on both. Very sharp brakes on the initial feel and progressivly softens the more you push down to full braking force.

For me this works well as the prelude is NA so the progressive throttle response works well where the s660 and VW t6 are turbo and both have that sudden turbo response on initial throttle.



Very odd how yours changes.
I have never had experience with Ds2500 pads however I doubt they are the reason. Very respected pads, discs wouldnt change like that, fluid is good so it must be the unit that controls the fluid. The cylinder.


The Weight of your car is about what I'd expect an 4ws prelude to be 1380kg however I don't know wheather the UK brochure includes a full tank of fuel.

it doesn't change often - its very rare indeed. A glimmer of hope. I have 1 brake clamp already, just ordered another. infact the more i think about it, the more i realise it was a symptom of that rear guide pin seizing up (it was so stiff i had to use a set of pipe wrenches to twist it free and remove it).

Is there such a think as too much grease on the slide pins, causing a hydrolock at the bottom of its travel? I'm using some 3m stuff that has been decanted into syringes. I tend to press them in, and then remove any excess that eventually oozes out before fitting the dust boot which tends to make it air tight...

I'll clamp up both rears when they arrive and go for a spin - that should rule out or in any ill affect of the rears and go from there. I wont order the MC just yet, as im not 100% confident its the right part (Not sure i will ever be confident on that front lol).

Don't fancy a track day at abingdon do you ratty? Can compare and contrast then lol.