Hydraulic Handbrake

[cheekychimp]

We sat and puzzled over this for about 30 minutes today, after which I came home and got on the internet to try and work this out.

After fitting the huge rear discs and 4 pot rear calipers I have no handbrake. I intend to convert the existing handbrake assembly to a push rather than pull operation (refixing the pivot point on the bottom to the top to drive a master cylinder).

There are different ways this could be done, either using the 4 pot calipers as the handbrake by putting the e-brake master inline, or making the handbrake independent by adding a second one or two pot caliper on the opposite side of each rear rotor.

Pros and Cons to each?

Also for the brake gurus, I have something niggling at the back of my mind about our brake system being diagonally opposed because of the 2-channel ABS. My ABS is now eliminated but will I still have problems routing the lines? As I understood it if I use the 4 pot calipers, I need to cut the two lines going to the rear calipers and use a Y-fitting to run them into a single line to the e-brake master cylinder. The single line from the e-brake master then has to be fed to another Y-fitting splitting to the left and right rear calipers. If the brakes ARE diagonally opposed, how does this work out?

 

[Rausch]

Quote:
making the handbrake independent by adding a second one or two pot caliper on the opposite side of each rear rotor.


this gets my vote. for two reasons. one. it's seems more straightforward. and two, it seems to me that if its good enough for Ferarri, etc. it's good enough for the Galant.

Not very technical, i know, but i think it would be better to use a dedicated handbrake caliper, if for no other reason than to keep the systems seperate, and thus simpler to design, and diagnose. /ubbthreads/images/graemlins/dunno.gif

 

[Gordian79]

Do you just want an ebrake?You can use a manual line lock on your rear brake lines.I used to use when i did 8.8 ford rear end swaps into corollas.basically you pump the pedal a couple times push the button down and your rear wheels are locked.To release just tap break pedal.The company on makes is called jebre or something like that they make vw parts.

 

[cheekychimp]

Quote:
Quote:
making the handbrake independent by adding a second one or two pot caliper on the opposite side of each rear rotor.


this gets my vote. for two reasons. one. it's seems more straightforward. and two, it seems to me that if its good enough for Ferarri, etc. it's good enough for the Galant.

Not very technical, i know, but i think it would be better to use a dedicated handbrake caliper, if for no other reason than to keep the systems seperate, and thus simpler to design, and diagnose. /ubbthreads/images/graemlins/dunno.gif



Makes sense Aaron, my only concern is that the Ferrari system was designed this way from the factory. There are no 'ears' for a second caliper on the VR4 which means welding brackets direct to the lower arm. Any strength issues here?

 

[cheekychimp]

Quote:
Do you just want an ebrake?You can use a manual line lock on your rear brake lines.I used to use when i did 8.8 ford rear end swaps into corollas.basically you pump the pedal a couple times push the button down and your rear wheels are locked.To release just tap break pedal.The company on makes is called jebre or something like that they make vw parts.



This may work as a stop gap and would actually make a very nice e-brake, but I was also hoping to indulge in a little lever pulling, hairpin u-turn action /ubbthreads/images/graemlins/devil.gif

 

[kartorium]

I would say just find a lightweight caliper single piston for the ebrake and make a dedicated system for the ebrake. I imagine it would cause you less headache and would be effective if you have the sources for bracket fab for the new calipers. Lines will be simple, and so will adjusting the system.

I'm not following the second half of your post. It keeps confusing me as I read it. If all of the abs stuff is removed, and you don't have the stock Pvalve anymore the system should be pretty straight forward.

If you make sure everything is fabbed welded and aligned correctly there shouldn't be too much stress on the ebrake caliper itself. Are you doing a custum rear arm setup? Or is most of it stock?

 

I'd go with the separate system too, for safety reasons. If the main system had a leak, your e-brake also wouldn't work because the fluid would exit the same leak, leaving you with no brakes at all, potentially just as you approach a very busy intersection!!!! Unless there is some kind of non-return valve you could put between the main system and your e-brake setup

 

[kartorium]

good point^ The safety benefits of having a seperate system would be the kicker for me.

 

[Rausch]

+ a bunch to the above posts. i don't see strength being an issue, provided the material and welding is of good quality. as said above, the calipers would not endure anymore stress than the rears themselves, probably less to be more accurate. i think a decent bracket and a nice smaller single piston caliper would do the trick. i have given this some thought before, as it's something i would like to do myself in the future.

on a side note, i noticed the other day that the MAybach runs dual calipers, only these were on the fronts as well......big ass brakes!!!

 

[cheekychimp]

Quote:
I'm not following the second half of your post. It keeps confusing me as I read it. If all of the abs stuff is removed, and you don't have the stock Pvalve anymore the system should be pretty straight forward.

If you make sure everything is fabbed welded and aligned correctly there shouldn't be too much stress on the ebrake caliper itself. Are you doing a custum rear arm setup? Or is most of it stock?



I'm sorry if my post is confusing. I don't want to spread incorrect information which is why I was posting as a question, but I was under the impression that in stock form, our ABS split the braking front left/right rear and vice versa rather than just front and rear. I never understand this exactly, nor was I able to verify with any certainty if it was correct. I presume from what you have said above that installing a non-abs proportioning valve removes the diagonally opposed brake line routing and makes this a straight front rear setup ... yes?

As for the rear, I can hardly call it stock since the 4WS has been removed and Larry's toe elimination kit installed along with Andre's chromoly upper control arms, but I think I know what you are getting at here, namely that with the main part of the original rear end intact there is ample space for the welds on any custom brackets so it is not as if the brackets will have to be supported by two spot welds on a skinny aftermarket tubular arm.

I can see the logic in what has been said above, ease of installation, safety, ease of troubleshooting problems/failures etc. So it looks as if the consensus is that I need to start looking for some light one piston calipers that will fit 28 mm rotors.

 

[kartorium]

Here is my thoughts and experience. You def clarified it better that time, but i think I was just getting confused from your first post by all the mention of Y's and whatnot /ubbthreads/images/graemlins/grin.gif

diagonal distribution is correct from what I've read, but that is with stock abs, stock abs Pvalve. Once you remove those two items what is left? The master cylinder. Now is the master cylinder splitting things diagonaly? From what I have decided and experienced, no. It doesn't make any sense anyways if someone was to argue that the stock MC is creating this distribution. What I have done on my car is simply deleted the abs, removed the stock Pvalve, and in its place put a wilwood adjustable valve. With the valve fully open it would lockup the rear FAST in the snow. One port of the MC goes to the wilwood valve then to a T fitting, and the other port goes to a T fitting then to my front brakes (no valve in line). Things seem to be fine, and the car brakes like a champ, especially from 70+mph. The pads heat, and bite like a motha, no pulling left or right. From what I can tell this system is currently safe, and works very well. If someone thinks that it is flawwed, speak up. The car has been this way for 6 months maybe.

So, yes, after you remove all the stock abs sh*t and stock pvalve it should be straight front to rear. HAHA, i just thought about it, if it was diagonal somehow, my car would really be freaky to stop in /ubbthreads/images/graemlins/blush.gif

I am pretty sure wilwood makes calipers specifically for what you are doing. They are lightweight and simple too IIRC.

You got what I was saying about "stock". I should have been more specific, but I figured you'd get it /ubbthreads/images/graemlins/smile.gif

 

[cheekychimp]

Can you post a link (or send me a PM) of the hardware you are using. There is a Wilwood dealer in town. I'll go and check if he has any single piston calipers. Last time I was there to check on fittings he had some HUGE brakes (406 mm rotors) /ubbthreads/images/graemlins/jawdrop.gif

Made my brakes look small ... lol!

 

For a slightly option, on their IRS, Jaguar used a disc mounted on the "nose" of the diff pinion, with a cable operated caliper clamping it...less unsprung weight would be a bonus as well. If you are using a locked/welded center diff, I think this would lock all four wheels though...

 

[curtis]

Paul

the circle track store in town has wilwood e brake calipers, single piston and small, there mainly for parking brakes they also have steel weld on brakets. If you want it really crazy look up the dune buggy stuff they steer with the brakes on trials and the dirt. Two handles two calipers. CNC brake corp. is one of the VW dune buggy places...


I just checked and scogins website is down but they have them on the sheilf along with the outlaw series which is cheaper and tilton and alcon stuff as well.

 

[Gordian79]

Quote:
Quote:
Do you just want an ebrake?You can use a manual line lock on your rear brake lines.I used to use when i did 8.8 ford rear end swaps into corollas.basically you pump the pedal a couple times push the button down and your rear wheels are locked.To release just tap break pedal.The company on makes is called jebre or something like that they make vw parts.



This may work as a stop gap and would actually make a very nice e-brake, but I was also hoping to indulge in a little lever pulling, hairpin u-turn action /ubbthreads/images/graemlins/devil.gif




no hairpin u-turn action for u.your drivetrain will thank you.even though its a beefy one at that.heres the thing i was talking about.

 

[toybreaker]

Excellent topic, Paul, I really like the idea of a stronger e-brake!

I do have question or two though...

Because of the center diff and viscous coupling, I have only had moderate success turning the car with the e-brake. Most of my spirited driving is on loose surfaces, (dirt/snow/ice), and I've noticed that a hard enough pull to lock the rear wheels in an attempt to generate oversteer will also transfer enough brake force to the front wheels to do some strange things,...(i.e. four wheel lock up, or the car will only rotate ~partway~ and then it will just slide sideways...) I can release the handbrake, step on the service brake, add throttle, pop the clutch, or a combination, and it just continues to slide sideways, and not rotate the way I want it to. I live at 9200ft, on a combination of road surfaces from tarmac, to loose gravel and hard pack dirt, so I get to practice a lot. /ubbthreads/images/graemlins/devil.gif I can work a rwd or fwd platform with the handbrake to intiate momentary oversteer fairly well, (and even a wrx, with a diff disconnect) but I don't have much luck with the dsm/vr4 set-up. It's just not consistent enough, and I can drive faster, with more comfort and control by reserving the handbrake for very special occaisions/low speed hairpins only. I have found that a quick, hard pull with the clutch in, then a bunch of throttle, and a quick clutch release gives the best transition to oversteer and the most repeatable results. (but I don't even pretend to be a good driver.)

I can only attribute the unpredictable behaivior to the fact that the locked rear wheels are transmitting force thru the center diff/viscous coupling, and this force will then act on the front wheels. /ubbthreads/images/graemlins/dunno.gif

Some of the more sophisticated awd platforms will disconnect the rear driveline when the handbrake is actuated. Unfortunately, Mitsubishi didn't check that box when they spec'd the gearbox for the US market gvr4's.

My high mileage eclipse GSX (without rear lsd) had a loose coupler in the trans, and it would handbrake ~ok~, but my tsi and vr4 (with four bolt/lsd rear diffs) and good viscous couplers in their trannies are unpredictable when the handbrake gets yoked. My theory is the handbrake doesn't only affect the rears, leading to the unpredictable behaivior. (I would love to hear other peoples opinions on this!!!)

In addition, I think there may also be some ramifications and reprecussions to the transmission from this force transfer. The center diff will be extremely stressed by the differing rotating speeds, because the viscous coupler in the transmission is hella stiff, and it will transfer as much force to the front half of the driveline as it can.

The pinion gears in the diff will put HUGE thrust loads against their washers, potentially breaking them. This can cause all kinds of trauma, up to and including catastrophic diff failure. (Especially if the diff gears chew on the washer halves)

The side gear thrust washer will also be very heavily loaded against the output shaft flange, and the difference in rotational speeds could gall/sieze the washer, resulting in a siezed input/output, and a ruined front diff case.

At the very least, the constant shearing of the viscous coupler fluid will accelerate it's demise, if the handbrake is yoked on a regular basis.

I haven't actually broken anything in my transmission, because I generally only get rowdy on loose surfaces, but I could see some potential issues on the street, with sticky tires.

All that said, a well functioning emergency brake has saved my ass (when the primary hydraulic system had a hose failure) at speed, so In my humble opinion, it's worth whatever hassle it takes to have a separate system to fall back on in case of emergency.

And if it lets you square off a turn or two, so much the better. /ubbthreads/images/graemlins/worthy.gif

 

[cheekychimp]

Well the Cusco centre diff is essentially a 4 spider with a viscous coupler eliminator, but given your points above I don't think that will help. Infact it would most likely put more strain on the drivetrain as the clutch lock up to 50/50 would be almost istant when the rear wheels lose traction. I think you are absolutely correct in that a far as potential damage to the drivetrain is concerned, this type of manouevre is only really 'safe' to perform on loose surfaces.

As far as unpredictable behaviour is concerned, I would say the type of diffs you have (and the different combinations of diffs you use) will heavily affect behaviour as it gets far more complicated than either a FWD or RWD setup. A welded centre diff or a clutch pack centre diff locked up will significantly help in maintaining that e-brake induced oversteer. Remember AWD cars by their very nature tend to understeer and it can take a lot of setting up (suspension, swaybars etc) to counteract the cars natural tendency to try to straighten up from a sideways slide.

As for reducing drivetrain strain, I only use this type of manouevre to make tight u-turns around central dividers. As such it is a bit different from the powerslide/drift type manouevre rally drivers do. I approach the intersection in the fast lane, brake, start to slowly turn in, then as I reach the gap I push the clutch all the way in, pull the e-brake on and turn hard on the steering wheel. I pretty much wait for the car to stop rotating, before engaging 1st and letting the clutch out. I'm not saying that doesn't put any stress on the drivetrain but I think it is a far cry from forcing the rear to lock up under power!