moshy brakes

[nicolas]

been spending some money to make my brakes better, but i still end up with a lot off travel on the pedal.
and when i step on the brakepedal the second time it firms up quicker. like there is less oil the first time.

here is what i use so far

CSP 21mm mastercylinder
regular lines with a linelock (has one oilline in and two out, doubles as a splitter)
rubber flexibel hoses
front discbrakes are talbot horizon (refurbished and no leaks)
rear are type3's.


not really sure how to fix it. or what i am overlooking. maybe the reardrums? or the amount of oil needed is still not enough...

[Zach Gomulka]

Adjust the rear drums, then bleed all 4 brakes.

[nicolas]

the drums are the hard part. i set them as close as possible but that seems to be not enough... i have thought about it as well. but that would mean that i can't adjust them...

[Fastbrit]

You need a residual pressure valve in the front brake lines...

[Tony M]

Make sure that there is free play in the brake pedal - most brake problems are that the b/pedal has no free play - set it like your clutch - aprx. 1/4 in free play - adjust rear brakes till they wont turn then back them off about 3-4 notches - bleed from right rear to left rear - then right front to left front - make sure that your e/brake cables are loose at the handle - adjust cables at the end. Hope this helps -

[nicolas]

You need a residual pressure valve in the front brake lines...

how do i know if ihave one? i have the type3 master cylinder from CSP it claims to be good for their discbrake conversion as well so i hope it is OK for me as well.

maybe Gunter knows more about it?

Make sure that there is free play in the brake pedal - most brake problems are that the b/pedal has no free play - set it like your clutch - aprx. 1/4 in free play - adjust rear brakes till they wont turn then back them off about 3-4 notches - bleed from right rear to left rear - then right front to left front - make sure that your e/brake cables are loose at the handle - adjust cables at the end. Hope this helps -

i wll recheck everything again, but it looks like i covered all the bases. except i bleed the fronts from left to right at the front due to the linelock at the right side.

i have been having the problem for a long time, but i have had firm brakes and now it doesn't seem to work as good as i want it to. so i am a bit bummed. it probally is something in the adjustment that i keep getting wrong.

will get back later with more info.

[j-f]

Do you set the handbrakes too? If it is too loose, the travel of the pedal will be too long.

[besserwisser]

My experience says its the linelock that is causing problems. It has to be mounted very low under the brakecylinder and when I bled the brakes I raised the rear of the car up about 80 centimeters.

[gibber!]

You need a residual pressure valve in the front brake lines...

how do i know if ihave one? i have the type3 master cylinder from CSP it claims to be good for their discbrake conversion as well so i hope it is OK for me as well.

maybe Gunter knows more about it?

The residual valves screw into the master cylinder before you fasten the front brake lines to the cylinder.
They look something like this:

http://www.vwspeedshop.com/store/product.php?productid=16528&cat=304&page=1

....the original VW ones are smaller.

[Cornpanzer]

Do you set the handbrakes too? If it is too loose, the travel of the pedal will be too long.

The handbrake should have no effect on your pedal feel.  It is a simple mechanical system while your service brakes are hydraulic.

That being said, if you pull the handbrake up a couple notches and your pedal gets firmer, this is an indication that your rear shoes are not adjusted properly.  The handbrake is simply closing up the air-gap that you have between the shoes and the drum.  Adjust the shoes, not the handbrake.

Remember, you need to feel some light drag on the rear brakes when you spin them by hand if you want a firm pedal.  What I was taught is to tighten the shoes evenly til the wheel locks and then back them off one click at a time alternating shoes til the wheel releases and spins freely.

If you have a high pedal, yet it is spongy, then re-bleeed them.  This can be a real pain on a fresh system.  A vacuum bleeder is a wonderful thing 

KS may be on the right track with the residual valve, but I have never needed one in any of the disc conversions that I have done. 

[nicolas]

no residual valve in my system. so i might have to look into those. but do i need one right after the master cylinder or two exiting from the linelock.

but i will check the rear brakes first with the 'handbrake technique' becaus i suspect the rear brakes to be the problem. i always back them off until there is no rubbing. but that can be too much. brazilian drums may be the problem as they may be out of spec (oval) i need to check that as well...
i have heard that drumbrakes need more oil then calipers,...

thanks allready will keep you posted.

(love weekends.... )

[Fastbrit]

Personally I would run one in each front brake line, but you may get away with one at the master cylinder. In my experience, though, you'll never get a really firm brake pedal when using a line-lock. The brakes work, but lack that solid feel of a stock system.

[nicolas]

thanks for the help allready,

here is what i have come up with so far.

the rear brakes don't lock up when i brake on sand. the fronts do, but indeed need a good hard push.
with the 'handbrak-test' the pedal is a bit stiffer and travells less when the handbrake is on. but i still have to push twice to fill the lines. or it feels like this. the first push is filling up the lines and the others are the same and pretty firm. but how can i make the first as firm as the others.

boy does it feel weird talking about firmness in relation to brakes... 

[j-f]

Do you set the handbrakes too? If it is too loose, the travel of the pedal will be too long.

The handbrake should have no effect on your pedal feel.  It is a simple mechanical system while your service brakes are hydraulic.

That being said, if you pull the handbrake up a couple notches and your pedal gets firmer, this is an indication that your rear shoes are not adjusted properly.  The handbrake is simply closing up the air-gap that you have between the shoes and the drum.  Adjust the shoes, not the handbrake.
 

OK. But on my car, if the handbrakes is to loose, it don't work correctly. The drums are original in good state, brake shoes are new and good quality. When I install it I check to put them in the good way and set the brakes until the shoes rub drums. Then, I adjust the handbrakes. I always have good braking and no problems at annual tech inspection.

[Fastbrit]

thanks for the help allready,

here is what i have come up with so far.

the rear brakes don't lock up when i brake on sand. the fronts do, but indeed need a good hard push.
with the 'handbrak-test' the pedal is a bit stiffer and travells less when the handbrake is on. but i still have to push twice to fill the lines. or it feels like this. the first push is filling up the lines and the others are the same and pretty firm. but how can i make the first as firm as the others.

boy does it feel weird talking about firmness in relation to brakes... 

This does suggest you need residual pressure valves. That first push of the pedal moves the pistons in the calipers, taking up the 'freeplay' between the pad and the disc – the second time you push the pedal, the pistons/pads are already close to the disc. A residual pressure valve stops all the fluid from draining back from the caliper, keeping the pad in light contact with the disc at all times.

[nicolas]

thank you, i might go for that route as it 'feels' unsafe to push twice. i have seen the link for the valves, but i may need a address here in belgium as the £ is still a bit high. turns out to cost about 100 euros to ship them to me... a bit too pricey for safety... 
i also think i need to get the drums machined so they are round and so i can adjust the screws a notch or two further.

[Frank LUX]

thank you, i might go for that route as it 'feels' unsafe to push twice. i have seen the link for the valves, but i may need a address here in belgium as the £ is still a bit high. turns out to cost about 100 euros to ship them to me... a bit too pricey for safety... 
i also think i need to get the drums machined so they are round and so i can adjust the screws a notch or two further.

Nicolas,

Please don't Take this Wrong, BUT SAFETY HAS NO PRICE...!!!

Frank

[nicolas]

frank i know what you mean. it was sarcasm... i know it doesn't really come across when i type it, but i plan on driving the car with my wife and son... so money isn't really going to stop me from buying the pressure valves.

thanks for your concern, you are right, safety first, even (read especially) if you like to play with more horsepower.

any leads on finding those in belgium?

[nicolas]

i found some at CB, but not sure which ones i have to order??? can someone help me? thanks. 2lb, 4lb, 10lb (but those are for drums) i was thinking about a single one right at the mastercylinder before the linelock to have equal pressure at all times towards the brakes... not sure if my thinking is correct or the best option.

[nicolas]

TTT

 

i still am not further on the one or two pressure valve issue and the size that i need. please help as the season is approaching and i may get the engine at the end of the month... 

[benssp]

 WILWOOD RESIDUAL PRESSURE VALVES:
These in-line pressure valves retain a minimum brake line pressure to help eliminate excessive pedal travel in both disc and drum brake systems.

The two pound valve is used in disc brake applications where the master cylinder is mounted below the horizontal plane of the calipers and fluid drain back occurs from gravity and vibration, thereby causing excessive caliper piston retraction and a longer brake pedal stroke. The minimal two pound residual pressure prevents fluid from flowing back without causing the brakes to drag. With drum brakes, a ten pound valve is used to compensate for return spring tension in the drums. Residual Pressure Valves are made from billet aluminum and color coded for easy identification. Ideal for drag racing, street rod and many off road applications.

Use the drop down box to confirm 2lbs or 10lbs valve.

[nicolas]

thanks Ben

i found that info as well and like the idea behind those as they are just bolted in line an look good too. but i still haven't figured out if i need only one right after the master cylinder (like CB shows them) or exiting on the line lock. two different ones that can fit the 1/4 NPT tread off the linelock...

i have mailed CB to have a quote on the total price, so i guess i will go with those as they seem to have one that fits the original master cylinder.

[nicolas]

OK so in all the fuss i forgot to tell you guys i got my valves yesterday and now i need to install them. just to make sure if it will work.

i have two 4lbs valves which i plan to mount both on the exits of the linelock

so the layout is:

one master cylinder with one line going into the linelock

two exits on the linelock with at both sides a 4lbs residual pressure valve

two lines going to talbot brakes.

can this work? i have read that JR had a similar problem but with a stagingbrake and that Keith suggested to add the valve right after the mastercylinder... so will my setup work? or not? can't test it.

[Mike Lawless]

Here's some other stuff to look at if the residual pressure valves don't cure the problem....

http://www.cal-look.com/forum/index.php?topic=23660.0

[nicolas]

thanks some good info there as well. note that it is indeed the furthest lines first and that with a linelock on the front wheels the lines to the left are longer then those to the right. in fact i just swapped left for right and visa versa on the car as i installed my linelock on the right side where the master cylinder would exit from a RHD car.

[Buttons]

i have the same problem on my '56 so have been watching this topic with much interest!

The residual valves screw into the master cylinder before you fasten the front brake lines to the cylinder.
They look something like this:

http://www.vwspeedshop.com/store/product.php?productid=16528&cat=304&page=1

....the original VW ones are smaller.

So then.... do you need 1 valve or 2??

[Buttons]

i have the same problem on my '56 so have been watching this topic with much interest!


Quote
The residual valves screw into the master cylinder before you fasten the front brake lines to the cylinder.
They look something like this:

http://www.vwspeedshop.com/store/product.php?productid=16528&cat=304&page=1

....the original VW ones are smaller.

So then.... do you need 1 valve or 2??

[nicolas]

i have installed 1 that has 4lbs pressure and it works for my front discs. big discs. still have drums at the back. and everything locks up pretty firm.