AE86 proportional valves (brakes n shizno)

[rthy]

For the vehicles we are interested in, the proportioning valve turning point is set at:
AE86, ADM = 15kg/cm^2
AE86, JDM GT with drums, Euro GT with disk = 20kg/cm^2
AE86 with disk rear, AE85, some Euro = 30kg/cm^2

It is worth noting that these same valves come on a host of Toyota vehicles, including the 1977 Mini made in Australia. Also, the AE85 (with drums) uses the exact same p-valve as the GTV and GT-Apex models with disks.

Update: All of my assumption are incorrect. See Jonny's post on the 2nd page

Due to the lack of proportional valve stock at toyota... whats the difference between the rear drums and disk proportional valves?
besides the drums has a single piece proportional valve and disk two piece?
is there a way to modify the drum propvavle to work with disks the same way as the disk propvavle?

the reason why i ask is that the drum wheel cylinders require more liquid for the shoes to hit the drums... so when swaping over to a disk rear end the rear brakes force will be stronger than the front.

i did look around on the internets but didnt find anything solid with modding to the drum pv to use on disks rear ends.


edit: this is for drum to disk rear end, factory swap over
Using the Factory ADM PV can you modify it to use disk rear end?
not after adjustable/aftermarket pv as i would have got one along time ago.

[Vance]

removing the spraings theory-

it makes it easier to open the valves which makes the front brakes work earlier.

i havent tested it personally

[LittleRedSpirit]

Just get the same proportioning valve as the diff came with. Failing that you could always use something like this in the rear line to the diff, after the factory proportioning valve:


If all you need is to limit the flow, thats all you need.

[n00bvak]

^^^ I have a willwood adjustable proportioning valve setup for my hydraulic handbrake, really easy to setup and way lighter than the stock one.

And by far the best thing is you can setup whatever brake bias you want!!! :P

Check my build tread link below for instal pics (its on the side of the hydraulic handbrake)

[rthy]

yea hard finding a factory disk pv, bought a rear pv from toyota but they no longer have stock for the front pv! so might have to buy second hand or other way.

not looking at getting a flow limiter at this stage

edit:
also which spring is removed?

[reecegze]

ive got r32 bmc , hilux front brakes and r31 rear disc brakes.. I am just running the stock pv seems to be sweet ??

[rthy]

thats cos u got the bigger mc, im still using the factory MC, factory jdm front brakes, factory jdm disk rear end and factory adm drum PV. so once the brakes heat up the rears lock up pretty easy which only happend at winton.

if i get paid tommorow ill buy some brake fuild and try removing that spring and see wat happens.

[reecegze]

i see upgrade to r32 ?

[rthy]

with the stock brake? nahh

altho i do plan on using a r32 bmc on my ae71 with rx7 brakes n stuff

[Hen may possibly be a nut]

Try just pulling the spring out of your current valve. The bit that deals with the rear lines, open it up, remove spring and put it back together. I did that years ago and seems to work.

At least give it a try before chasing expensive parts around the country.

Hen

[rthy]

So thats the spring from the bottom of the adm pv that goes to the rear brakes?

http://img23.imageshack.us/img23/928/pvadmrp8.th.jpg (http://img23.imageshack.us/my.php?image=pvadmrp8.jpg)

[Hen may possibly be a nut]

I can't remember, it was years ago. Bottom rings a bell, but I just pulled it apart and investigated.

Hen

[rthy]

kool thanks, will check it out tomorrow

[rthy]

ok took apart the adm pv and jdm rear pv
http://img12.imageshack.us/img12/6092/dsc00343ou7.th.jpg (http://img12.imageshack.us/my.php?image=dsc00343ou7.jpg)

ADM PV (rear side), spring, piston, spring seat and nut
http://img24.imageshack.us/img24/2871/dsc00338pb8.th.jpg (http://img24.imageshack.us/my.php?image=dsc00338pb8.jpg)
in side the rear half of the adm pv
http://img99.imageshack.us/img99/1931/dsc00339wx7.th.jpg (http://img99.imageshack.us/my.php?image=dsc00339wx7.jpg)

JDM rear pv, spring, piston, spring seat and nut
http://img99.imageshack.us/img99/3174/dsc00340tc3.th.jpg (http://img99.imageshack.us/my.php?image=dsc00340tc3.jpg)
inside the rear jdm pv
http://img24.imageshack.us/img24/7825/dsc00341iw1.th.jpg (http://img24.imageshack.us/my.php?image=dsc00341iw1.jpg)

so it looks like some fluid from the front half of the adm pv goes to the rear as well.
so not sure how removing the rear sping will help?

ADM PV (front), spring and nut
http://img24.imageshack.us/img24/5246/dsc00348ce2.th.jpg (http://img24.imageshack.us/my.php?image=dsc00348ce2.jpg)

inside the front half of the adm pv
http://img24.imageshack.us/img24/9421/dsc00351po5.th.jpg (http://img24.imageshack.us/my.php?image=dsc00351po5.jpg)
(note the thing in the middle is not a hole)

was thinking of a way to block fluid from the front half going to the rear, maybe cutting it someplace and welding that hole
http://img24.imageshack.us/img24/6310/dsc003442uq7.th.jpg (http://img24.imageshack.us/my.php?image=dsc003442uq7.jpg)

[rthy]

http://img99.imageshack.us/img99/5122/pvomgxg9.th.jpg (http://img99.imageshack.us/my.php?image=pvomgxg9.jpg)
This is how i think the PV is working

since the jdm disk is a 2piece the additional passage for more fluid to the rear isnt required.
so maybe cutting and welding up the hole will be the pov workaround to get the rear disks working the way they should?

[LittleRedSpirit]

I found some terrific links while researching some brake concepts a while back. Here they are. They have some sort of explanations about proportioning valves in there I believe.

http://dsr.racer.net/brake_bias.htm

http://www.pbr.com.au/technical/documents/HYDRAULICBRAKESYSTEMSGUIDE.pdf

[rthy]

thanks, but im looking for into on the ae86 pv's
i would buy the jdm front half pv but they are no longer available from toyota (or so says the parts guy at essendon toyota)

[LittleRedSpirit]

Yeah you're right, fuck learning anything, its much easier to put your bib on, open your mouth, and here comes the aeroplane. Just hang around until Johnny Rochester shows up and tells you everything.

Ill spare you the 10 or so explanatory links I just found then, since you're not willing to read shit.

What a waste of 15 minutes.

[rthy]

i already have read up on how shit works along time ago before asking this questions

i guess what im really after is the factory specs of the adm and jdm PV

Not all PV's are the same, and the ae86 came with a few different designs for drums and disk brakes.
As we all know the drums require more fluid as they use wheel cylinders.
http://www.lubemobile.com.au/SiteMedia/w3svc621/Uploads/Images/wheel%20cylinder.jpg
So how does this ADM PV put more pressure to the rear wheel cylinders?
As mentioned above, there is an additional passage from the top part (that controls the front brakes) of the ADM PV connects to rear half of the PV.
By eliminating this extra pressure from the front half, will this reduce the pressure to the rear brakes to act like a factory disk end? i assume so?
i dont think removing the spring from the rear half of the adm PV will work, as it will allow more pressure to the rear?

OR are the JDM and ADM Master cylinders also different?
as for the removing the spring from the master cylinder on the rear half so less pressue is applied to the rear, that seems to work but not correctly.
as the pressure to the rear is being applied via that additional passage and not the proportional section of the rear half of the adm pv. i assume so too?

so removing a spring doesnt seem logical, unless proven.


Also: anyone got pics of the front section of the JDM PV or part number?
JDM Rear Prop Vavle: T47150-22050

[n00bvak]

This seems like a lot of screwing around when an adjustable PV only costs $70 and bending a bit of bundy around a screwdriver.

It does the same as all the stuff you are trying to workout here, its lighter and fully adjustable for those sick burnouts with the rear lines locked :P.





not looking at getting a flow limiter at this stage

Especially if you may get on in the future

[Vance]

yeah but theyre illegal which is the problem. im gonna have to get one but am gonna hide it in a black plastic box

[n00bvak]

it is just the adjustment that makes them illegal, well here in WA anyway. If you take the adjustment knob off them (it just comes off) and heat shrink some plastic on it then it is non adjustable therfore legal.

This is what the guys at a performance brake place have been doing for years and registration has never been a problem.

[Vance]

well thats what ill do smart guy


seriously though, thanks for that info :))

[slydar]

you can buy in like proportioning valves from American speed shops. for disc or drum.

[n00bvak]

Rthy, this is how we have resolved "blocking the front fluid getting into the rear" issue
http://www.ae86drivingclub.com.au/dcimages/1/2/9/6959.jpg

[rthy]

im aware of how how the adjustable pv works was thinking for getting the adjustable prop valve, but didnt like the idea of having aftermarket pv's when the car can be stock as a rock.

so it safe to say no one has tried modifying the factory pv in away to block the additonal patchway to the rear.

my plan b was to get one from america or europe.

edit: first post fixed, want to use factory PV and not aftermarket ones.

[LittleRedSpirit]

Whats all the fuss about?

You know what parts to use to make it as it should be, so just get them.

Looks like no ones gonna explain it to you.

I bought a halfcut to get my bias valves and a low klm gearbox from it. In the end I was paid to get them.

:)

[rthy]

the fuss is: has anyone modded the factory ADM proportional valves to suit JDM rear disk brakes? more to the point, has anyone cut an ADM pv in half and welded shut the connections between the Front and rear brakes?

I assume not.

maybe my 1st few posts wasn't clear on my intention, appologies for the confusions...
looks like ill just do things the right way and get the jdm 2piece pv.

cheers

[LittleRedSpirit]

Well plenty of people mod them, by leaving out the spring, but I have a feeling its part of the tandem circuit failsafe that stops you losing all your brakes when one corner goes.

Best to use what Toyota has designed for the job, failing that, the aftermarket gear which you aren't so keen on.

Have a nice day.

[rthy]

Found one of those rear brake T piece on the diff
http://img12.imageshack.us/img12/91/difftp.th.jpg (http://img12.imageshack.us/my.php?image=difftp.jpg)
tried using it for the front brakes and the jdm pv to control the rear. the brakes work great now.
http://img12.imageshack.us/img12/2328/dsc00354.th.jpg (http://img12.imageshack.us/my.php?image=dsc00354.jpg)
made a small alloy bracket and bolted it to the factory location so that the splitter is not floating around

factory adm pv
http://img12.imageshack.us/img12/4329/dsc00359.th.jpg (http://img12.imageshack.us/my.php?image=dsc00359.jpg)

altho would still be interested to see if anyone has hackeds up the adm pv... :(

dont have anything agasint the adjustable pv, i just want to keep the car stockish, as for the ae71 dont really care cos its all going to be engineered.

[Jonny Rochester]

Due to the lack of proportional valve stock at toyota... whats the difference between the rear drums and disk proportional valves?
besides the drums has a single piece proportional valve and disk two piece?
is there a way to modify the drum propvavle to work with disks the same way as the disk propvavle?

The one piece and the two piece items both function the same way. There is no internal connection between front and rear fluid in these items. The working differences is the calibration of the proportioning valve. It is a generic p-valve body that Toyota have for most vehicles, and it works the same for disk or drum. The engineers obviously select a setting for that vehicle. The valve is not a one-way valve, and it does not regulate volume of fluid. A graph has to be used to show the exact function of it. The turning point, or refracted point in the graph, is what is used to name the different valve settings. When the fluid gets to a certain pressure, the valve starts reducing pressure to the rear in proportion to the master cyl pressure.

For the vehicles we are interested in, the proportioning valve turning point is set at:
AE86, ADM = 15kg/cm^2
AE86, JDM GT with drums, Euro GT with disk = 20kg/cm^2
AE86 with disk rear, AE85, some Euro = 30kg/cm^2

It is worth noting that these same valves come on a host of Toyota vehicles, including the 1977 Mini made in Australia. Also, the AE85 (with drums) uses the exact same p-valve as the GTV and GT-Apex models with disks.

If you have a "ADM" AE86 and just swap to the rear disks, and want to keep everything factory, you can use the p-valve off the RA40 Celica (just one of many vehicles). That is the exact same valve the disk brake models in japan had. So there you go... (I should be getting money for this... oh well).

If you have larger front brakes (and rear disks), or if you don't want to find a different p-valve, you can just gut your valve so it has no effect. Rather than just removing the spring, I think you should remove everything you see in there unless you figure how it works.

[n00bvak]

man jonny, how the hell do you find out this stuff???

*amazed* :thumbup:

[af300e]

man jonny, how the hell do you find out this stuff???

*amazed* :thumbup:

He actually reads playboy magazine for the articles.

[rthy]

Thanks Johnny, exactly the info i was after.

[sundee]

hey just thought i might add to this, when doing the rear disc conversion on my dato 1600 from drums to R31 disc's, The preasure relieve valve inside the rear section of the BPV had to be removed, this had something to do with it not allowing the release of the rear breakes propery or quick enough when u stopped breaking.. this pic posted on the 1st page.. all i had to to was remove the spring and that tube and put it all back together.



http://img24.imageshack.us/my.php?image=dsc00338pb8.jpg

[Jonny Rochester]

http://mjbobbitt.home.comcast.net/~mjbobbitt/mustang/mc/combination_valve_diagram.jpg

This shows a typical 1-piece proportional valve, like some KE30s had. At No.3 you can see a shuttle valve, which makes it appear that the front is connected to the rear lines. But this shuttle valve is there only to operate a safety switch, and light on the dash, if the rear brake pressure (from the master) should be different to the front brake pressure. The AE86 does not have this.

Law states you need a brake failure light on the dash. With the AE86, there is a fluid level switch on the brake fluid lid, which does this job. So a switch at the distribution block is not needed, but the 1-piece design remained.

[rthy]

so what is the difference between the to? like how does it control the cm^2? spring rate?

ie. if u put the disk rear pv spring into the drum rear end pv it should change the cm^2 to suit disk?

[LittleRedSpirit]

I assume at that listed pressure, the spring starts to compress. This will increase the volume of the line to reduce the rate the pressure increases, as you increase pedal pressure? The fluid pressure still increases but at a reduced rate?

Its a tandem brake system designed to leave you one end if the other fails, so they aren't connected, and really shouldn't be. Any failures should hopefully be limited to front or rear.

[Kid Karola]

I remember when i fitted JDM front discs and disc rear-end, I also fitted a 2 piece P-Valve consisting of T-Piece for front and a seperate bias to rear (Can't remember the Part #'s) think it was somewhere on the old site, more than likely from Jonny's epic Part # thread!) I think it was either kouki spec or superceded the one piece part #.

[Sam-Q]

I want to know exactly what that spring setup does inside the bias valve bottom end. I had and still had the combo of ma61 disks and calipers on the front and ae82 calipers with 280mm disks on the back. With the stock master cylender and then later to an upgraded 15/16" cylender I had so little rear bias it wasnt even taking the machining marks off the rear disks. After I gutted the bias valve I found I had ideal brake bias.. win!

[Jonny Rochester]

I think the spring is a big part of it. Maybe the main differences between the Toyota valves is the spring tension. Adjustable valves use adjustable spring pressure.

To learn more about this, I surgest getting into some automotive text books. Remember, books?

Confusing exists, because some vehicles do have residual pressure valves, designed for drum brakes. Some vehicles have a 1-piece valve which uses the front line pressure in some way. There are a few types... HiLux and HiAce and some Toyota wagons have factory load sensing, adjustable rear bias valves. (Works on suspension height). Some vehicles have the rear bias valve as part of the master cylinder.

But... I know the AE86 master is the same for all models, and has no valve in it. And I know the bias valves used, have the same item used on some disk brake cars, and some drum brake cars. Which to me, means a residual pressure valve is not used.

But don't take what I say as gospel. It's an interesting topic. Sort of like ackermann steering. Lots of theory, very little application.

[rthy]

the spring in the jdm PV is significantly more aggressive, i assume the ADM was softer because it was 20+years old. i would assume the spring controls the pressure

where do i find such text books?
i might stop buy toyota tomorrow and see if i can get part numbers for springs

[Jonny Rochester]

Toyota do not list the individual parts of the valve. They only list the valve assembly. I can give you the number for that if you want, not sure if it's available new.

For books, go to your local Tafe or Technical college, and go to the library. Find the automotive section. Most automotive text books try to be very broad and comprehensive. Automotive Mechanics by Ed May, a 2 volume book, has been the Tafe text for many years now. Everyone should have it.

Go the the brake section of the book, and somewhere in there will be a little chapter on proportioning or pressure limiting valves. I picked up a Heavy Vechicle mechanics book today, and it had a bit on these valves also.

[Sam-Q]

thanks for the tip Jonny I will have a look to see if I can find that book.

So when I gutted that proportioning valve I may of just made it have a 50/50 split of fluid?

[Jonny Rochester]

Yes. No p-valve means full fluid pressure to the front and rear, both the same. Then you need to test, brake hard and see if the rear brakes lock up. If the rears lock before the front, then you need a p-valve. If they don't, then you don't need one. ... I guess.

[Sam-Q]

ha funny that, and I always thought it was a preload for the fluid that the drum brakes needed to not drag or something, how wrong I was. I have fully tested mine on the road on and the racetrack and it seems to be balanced to perfection. So I can only take an educted guess and say that the front brakes conincidently need less pressure for the same amount of braking and so forth I end up with the right amount of bias? or am I making a really silly asumption again?

On another note I have heard of people using shims to preload that spring to have the same effect

[rthy]

Well thanks to that parts post
found the Part number to the stock pv's

http://www.toyodiy.com/parts/p_J_1984_TOYOTA_SPRINTER+TRUENO_AE86-FCMQF_4708.html

sexy site, has everything (for stock parts)

[Jonny Rochester]

Yes. But the hard bit comes when you want a cheap second hand part (or if it's not available), finding what other vehicle it comes on.

[Kid Karola]

Well thanks to that parts post
found the Part number to the stock pv's

http://www.toyodiy.com/parts/p_J_1984_TOYOTA_SPRINTER+TRUENO_AE86-FCMQF_4708.html

sexy site, has everything (for stock parts)

yes great reference... if you have a Trueno, not complete for Levin variants especially bodywise. Still win to have online parts interpreter handy for meachical bits.

I beleive the parts I used are marked 1 and 2 in that diagram.

[rthy]

yea i paid $200 for that rear pv brand new (1) from japan
the front half (2) are no longer available

looks like they dont sell they dont sell the spring seperate too

[Jonny Rochester]

I got the "ADM" AE86 one-piece proportioning valve today, and cut it in half. Just to double confirm what I said. Yep, it's solid metal. Front not connected to rear.

[Sam-Q]

good to know, so let me get this straight; the spring jigger is just a very crude preload that restricts the fluid flow for the rear wheels? You know this negates the need for any sort of bias adjuster if someone is willing to play with the stock one with different springs.

Jonny I honestly think your this forums best non operational resource

[af300e]

good to know, so let me get this straight; the spring jigger is just a very crude preload that restricts the fluid flow for the rear wheels? You know this negates the need for any sort of bias adjuster if someone is willing to play with the stock one with different springs.

Jonny I honestly think your this forums best non operational resource


Limits the pressure to the rear brakes, not the flow. I had the same idea with my skyline master. Bias spring is built in so altering the spring pre-tension should result in tuning of the rear bias.

If you really need a black and white illustration of how a bias valve works, have a look at a graph of their operation. It's then easy to see the effects.

[rthy]

I got the "ADM" AE86 one-piece proportioning valve today, and cut it in half. Just to double confirm what I said. Yep, it's solid metal. Front not connected to rear.

thanks, has anyone tried putting a ra60 pv spring into a ae86 pv?

[Sam-Q]

af300e: got a graph handy? I would really like to see one

[Jonny Rochester]

There is a hollow aluminium shaft with a coregated rubber seal at the end.

How it actualy works could bend my brain. It is to do with difference in pressure from front to rear, and maybe differences in the diameter of the alloy shaft. The shaft may move a bit...

I think the differences between the Toyota valves of this era, is just the spring. I have 2 springs here, a "ADM" one, and one out of a single style one. The ADM one is softer, but I can't remember what car the other was off.

I think you could increase spring pressure with washers, if you didn't have another spring to swap in.

[af300e]

af300e: got a graph handy? I would really like to see one

I'll have a hunt.

[Jonny Rochester]

http://www.winbrake.com/trainingmaterials/ProportioningAndLoadSensingValveDiagnosis.html
http://autospeed.com/cms/A_110601/article.html
http://www.geocities.com/nigel_warner/scimitar13.html

I think I could make an adjustable one using the Toyota one as a base. But it would be easier just to buy the Wilwood/Tilton valve.

[af300e]

^^^Thanks for those links. They have the graphs I was talking about.

What does a wilwood valve run costwise? $100?

[Jonny Rochester]

Yeah. $93 on ebay. Maybe $200 in a shop.

[rthy]

Found this guy today and thought of this thread lol
38263

edit: came out of my old adm converted trueno with a kouki rear end