1st gen VR4 brake conversion big issues :(

[TUFFTR]

Basically the brake pedal feels very soft and doesnt bite hard at all compared to the twin pistons. The master cylinder is pushing fluid out of the resevoir prett bad. Do the vr4's run a bigger booster or master cyl? Its pretty crap as im sick of brake fluid all over my nice car! I think this may be the reason the car doesnt feel like it brakes hard. (all new fluid, machined blank rotors, hawk hps pads) any help fellas?

[Pensky3thousand]

open all your bleeders one by one and make sure that fluid flows out of each. Verify that each one can easily be gravity bled. That will narrow it down to a collapsed line, or but most likely a blockage somewhere in the valves of the master or an internal leak. Do you have ABS?

[TUFFTR]

Non ABS car. I have bled all the brakes many times even beforehand and all of the calipers bled no worrys at all. Even the new calipers bled very easily! I have never had a leak when using the old twin pot brakes, as soon as these went on, BAM leaking from master cyl. Is there the possibility of it being an internal caliper issue? only reason I don't think it is is it's leaving a thin black film on both rotors on the front leading me to believe they arnt actually clamping hard on them at all.

[green-lantern]

Sounds like you might have a bad caliper. I want to think something is up with the rotor though. Like a warped rotor is pushing the pistons back in after breaking. Are you sure you don't have debris behind the rotor? I did this upgrade and it worked great. Did you put 1gen VR4 brakes on an NA or did you upgrade your 1st gen VR4 breaks to 2nd gen?

[TUFFTR]

Possibility in the caliper, however both rotors have the same black shit all over them. ive done a few brake conversions in my time and MANY sets of rotors/pads over the years (doing another set on an aristo thursday actually) and never had this problem! this is what my rotors look like currently...
http://i9.photobucket.com/albums/a52/dodgeviper89/IMG_0631.jpg
As you can see with black shit all over them from the pads, which should of worn off by now! thats exactly the same on both sides. Wont be warped as Ive only done 20-30k's and they are machined, so they are flat alright! No debris behind the rotor 100%, I am under the wheel arch regularly and when this conversion took place everything got cleaned well and proper!
argh.
How can you check to see if its a bad caliper?

[Alex3000gt]

Strange, I have no idea.

[TUFFTR]

That's really what I didn't wanna hear! lol

[GTOJOE]

If you stomp on the brakes does it stop like you would expect?

[TUFFTR]

Nope not at all, even with my foot firmly down the braking is substandard by anyones means. Def something not right here

[GTOJOE]

Master cycliner maybe? Have you asked this question on AMC? I'm sure there have been others fitting GTO brakes to a Magna? After going for a drive when you look at the caliper is the pad floating free from the rotor or does it look normal? I assume you bled them in the correct sequence? rear left, rear right, front left, front right? Have you inspected your brake lines? no swelling brake lines that might be expanding under pressure?

[TUFFTR]

1 Master cylinder maybe? 2 Have you asked this question on AMC? 3 I'm sure there have been others fitting GTO brakes to a Magna? 4 After going for a drive when you look at the caliper is the pad floating free from the rotor or does it look normal? 5 I assume you bled them in the correct sequence? rear left, rear right, front left, front right? 6 Have you inspected your brake lines? 7 no swelling brake lines that might be expanding under pressure?

1) Well could be, but my brakes worked totally fine before the conversion!
2) Sorta banned on there for a while, Plus no-one really knows anything on that website anyway
3) Actually AFAIK I'm the first!
4) It looks normal to me, but I will have the car on jackstands tomorrow and while it running get someone to press the brakes while I look at the caliper
5) Yes, always bleed in that order. Except when the new brakes when on the front I only bled the front. Rears were only done 500km's ago so no need to do all 4 again.
6) Again yes, My lines AFAIK are in good order. No signs of visual wear front or rear.
7) I doubt it, although anything is possible. if it was swelling under pressure, it wouldnt explain the master cylinder puking the fluid out.

Am I right in thinking I either need a bigger master cyl or one - or both - of these calipers need to be taken apart and inspected?

[tabasco122]

you generally need a larger MC when upgrading to more pots. It requires more fluid to get the same amount of pressure as your old brakes, so you old MC generally wont be up to the task. I dont think that would cause the fluid to come out the MC though, it would just give you bad brake performance.

[TUFFTR]

Understood. So It's strange how I have both symptoms. May start looking at a rebuild kit for these calipers. Knew I should of done this when i got them. ARGH.

[tabasco122]

i dont have any experience with 3s brakes, but that is how it goes when upgrading from the 4 (total) pot 240sx calipers to the 12pot 300zx system (front and rear). it sucks if you upgrade the brakes without doing the MC. you can usually get away with just the front brakes, but if you upgrade the rears too you need a larger MC

[TUFFTR]

Steve, Why do I need to bleed the rear ones if I only disconnected the hoses from the front and re-connected the new hoses right away? Would this in anyway cause what is happening?

[GTOJOE]

It's always a good idea to bleed all of them after working on the braking system. Better to be safe than sorry.

[TUFFTR]

I'll give that go on the weekend then. No big issues there, 5 minute job. I'll put it up on the stands tomorrow and see whats going on when I stomp on em. I would of thought the standard master cyl would of had enough force to push them. Who knows maybe both calipers do need a rebuild?

[GTOJOE]

I was more refering to what the pads look like after a drive. I was thinking that maybe the pads are being pushed back which would push the pistons back and cause the fluid leakage you are having issues with. However I'm sure you would feel it if there was warped rotors or movement etc.

[TUFFTR]

Definitely no movement. Rotors have just have been machined so yeah....HmMMMMMmMMmMMM

[Rocket]

If it was one brake I would say a bad rubber house going to the caliper. If it is all of then and you are pushing fluid out the mc then it almost has top be a plugged line. air in the system would give a soft peddle but shouldn't cause overflow from the mc. Bleed the rears and see how that goes.

Sent from my Droid using Tapatalk

[TUFFTR]

Okay, so should I take the front brake lines off and blow em out or something? how should I go about this? I am having a DIY day on the weekend with some mates (took an engine and gearbox out at my joint so it's all going back in this w/e) so if I had some steps to cross off so to say I could knock down a few possibility's this w/e.

So yeah, Must be in the calipers or lines as the previous lines and calipers worked fine! I just got greedy and wanted bigger :(

[GTOJOE]

Just re-bleed the whole thing. If they bleed fine then there is nothing stuck in them. Report back after this. Also the lines you are talking about... did they come with the GTO calipers? Have you check them? maybe they are swelling which is reducing your braking efficiency? None of this howevr explains why you would be getting fluid overflow.

[TUFFTR]

Yup. That's the problem. The fronts bled fine. hell just this week I did 2 brake bleeds. and like you can tell when there is an issue with pressure compared to the process going by the book.
So fucking weird. I just dont wanna bleed the whole system for no reason. Guess I might just to say It's done. Who knows. Pressure buildup is making me confused. Anyone else got some pointers? Sigh. Nothing ever goes right for poor pauly.

[tabasco122]

if you disconnect the front, you need to bleed the rear. there is a reason you bleed the brakes in reverse order. if you take off the brake closest to the MC (front driver usually) then you have the possibility of letting air into the whole system. just bleed them all, starting from the rear pass>rear driver> front pass > front driver

[TUFFTR]

Spoke to a brake guy today while getting some disc's for my mate's car with my situation and he said, like I suspected, if it's only happened once the calipers have gone on. It's probably the calipers. ordering a rebuild kit on monday from rockauto.com and in a few weeks will take them apart and see what the hell is going on.

Should I actually SPLIT the calipers apart or just do the pistons and seals and lube em up?

[TUFFTR]

:bump: should I get the master cylinder anyway off a VR4?

[GTOJOE]

Just try the caliper rebuild first. I don't think you will need to split them. Just change all 4 seals and boots and clean them and try again. Split them if you want to though. Who's car did they come off?

[TUFFTR]

Ahh well, my mistake really. they were sitting for a good 3 years off a car. Got it off a member of AMC who just had em laying there and needed the $.

Mmmm.....I'll do that. Even though I can see they are somewhat clamping I will do one thing at a time. I'll blow out the brake lines aswell just incase.

[TUFFTR]

Think I may of found a cause *hopefully not tested yet* which seems very logical and possible.

Disassembled both calipers, cleaned up the dust boots, recoiled the bores, checked for rust etc, what i noticed was a lack of lubrication on all 8 pistons/bores and the fact even with a full air compressor it was almost impossible to push the pistons out (due to lack of lubrication?) so I've reoiled everything and cleaned it all up, seems alottttt smoother now. Tomorrow or tues will rebleed and see how we go!

[GTOJOE]

Don;t think they need any oil/lubrication. The brake fluid is all the lubrication needed. Perhaps the issues are from the pistons not moving well but all you need to do is clean then [wet sand with very fine paper if they need it] and reassemble. Don;t use oil. When inserting the pistons back in wipe some brake fluid on them to help slide them in.

[TUFFTR]

Sorry Joe, But re-oiled I did mean brake fluid! So yes, lubed em all back up with brake fluid and I'm almost certain this should be it. Really should of done this when I got them a few years back. Im almost certain it goes like this
I put pressure on brake pedal > fluid gets pushed to all calipers to push out pistons > front pistons stuck at a certain point > pressure cant go anywhere > comes out the Master Cylinder instead.

buffed a few of up with 2000G, but they were actually in great nick for the most part. Will report back anyway. Spanks dudes.

[TUFFTR]

So is the fluid returning to the reservoir when you put the brakes on.?
That's a faulty seal in the master cylinder.

Steve

No idea, Never done this before the conversion, but it was pushing fluid UP and OUT the cap. Will see how this goes, if not, another master cyl will be going on.

[TUFFTR]

yeah but I always keep spares. I'll be getting one off a non ABS TJ magna (2002 model) for around $30, so it'll be cheap, and not 20 years old like the other ones. That's of course, if

[TUFFTR]

Re-bled the whole system again and took it for a drive around the block ~10 times. After lubing up the caliper pistons and taking it for a drive it defiantly feels 'better' but not 'great' Upon returning home and having a look, it looks like they are def biting the rotor a bit better. However I noticed it's pulling in the rubber at the front (i.e. closest to the front of the car) of the master cylinder.

Went wreckers, grabbed another master cylinder for $20. Will clean this up and get it painted, and suss out a rebuild kit while I'm at it.
*sigh*

[GTOJOE]

Maybe it's too small to push 10 pistons [8 on the front and 2 on the back]? that's a lot of fluid to be moved.

[TUFFTR]

I agree in part, doesn't explain how N/A 3000GT guys can upgrade with no issues though!

[GTOJOE]

All GTO have the same braking setup... Only different models are the USDM ones. Maybe they have the same master cylinders?

[TUFFTR]

Well by that logic, the NA master cyl will have the same as the TT.
I am thinking this is very well a master cyl issue. come to think of it now braking with the old twin pot's wasn't that great either....I always blamed the pads...(herpa derp)
I will get tot the bottom of this!

[tabasco122]

The amount of fluid moved is negligible. Changing the bore diameter of the master cylinder changes the ratio of pedal pressure to caliper pressure. It's just broken, that's all.

Steve

larger bore MC moves more fluid with the same amount of pedal travel, so thats just plain wrong

If you have a mc with a 1 inch bore and you push your pedal in 4 inches, it doesnt move as much fluid as pushing the pedal in 4 inches on a 1.5 inch bore mc. generally systems with more pots have larger MC's because there is more area to fill with fluid in order to apply pressure.

[TUFFTR]

I agree, This Master cyl was only bought out on cars with a total of 6 pistons. it now has 10.
however, It's the same MC as on NA GTO's (Its a 4 port MC, not 3 or 2) and they upgrade no problems, So I dont see why my car should be any different!
Anyway, you guys have been GREAT. I will leave the thread for a few weeks until I get my master cyl back on and let you guys know how it goes.
Thanks to everyone again.

[GTOJOE]

I agree, This Master cyl was only bought out on cars with a total of 6 pistons. it now has 10.
however, It's the same MC as on NA GTO's (Its a 4 port MC, not 3 or 2) and they upgrade no problems, So I dont see why my car should be any different!
Anyway, you guys have been GREAT. I will leave the thread for a few weeks until I get my master cyl back on and let you guys know how it goes.
Thanks to everyone again.

All GTOs hae the same braking system. NA or TT so that's not entirely true. It's probably the same as the NA 3000GT as it had different brakes. What is confusing is that these guys hae been able to fit TT brakes with no issues....... HMMMM......

[TUFFTR]

Well, Life really likes to fuck me up the ass sometimes.
Go to install the newer master cyl............3 out of 4 brake fittings rounded on me >< FFS! Yes, pipe spanner was used....always is...
What the worst thing is....each line from the master cyl goes directly to the caliper. No prop valve.
Fantastic, tomorrow I'm heading to the wreckers to see if I can upgrade to the later model brake lines or just replace the lines ive fucked and start again.
gah.....muprhys law of how a simple mechanical job ALWAYS turns into a hard one.

[tabasco122]

get some scrap lines, a pipe flarer, and some double female fittings and just replace the last foot or so before the mc.

[MR2]

what tabasco said :) double pipe flairers are not expensive...might as well do THAT yourself as well :)

why would you not get Gen II GTO brakes :p

also do you know of any GTO brake cyl refurb kits? mines leaking

[TUFFTR]

what tabasco said :) double pipe flairers are not expensive...might as well do THAT yourself as well :)

why would you not get Gen II GTO brakes :p

also do you know of any GTO brake cyl refurb kits? mines leaking

Car only weighs 1300kg.....I dont race with it so 317mm brakes are very excessive!
Check rockauto.com for the rebuild kits mate I;m certain I've seen them listed.

[MR2]

yeah found the kits and ordered :D just trying to think what other crap I might want.

[TUFFTR]

Changed the Master cylinder today aswell as one brake line. Polished the brake line before installation, looks pimp. Black master cyl looks much better too....doesnt stand out.
Managed to nip up the 2 remaining rounded nuts with a 10mm open ender. Tried 3 diff high quality flare nut spanners and they all have the same play. I reckon its 1/10th of a mm but just enough to start to round em.

Not pushing fluid up which is good, Bench bled the master before install and finally bled all calipers. The brakes feel OK. Nothing great just yet, will try em more during the week.
Decided to not change the other brake lines as the steering coloum needs to come out lol. Meh, brakes for now. That can be a job for another day!
Thanks fellas!

[MR2]

dude, best thing I found for those god damn things is vicegrips....fkn tightens those shits down ;(

[TUFFTR]

Yeah had to use vicegrips in the end to get them off. While I was there, replaced the two rear bleeder nipples for rounding aswell.

little tip for bench bleeding master cyl's, since my M/C has 4 ports, I blanked off 3 at a time with the spare bleeder nipples I had and bled one port at a time. makes for easy bench bleeding and a very easy install process!

[TUFFTR]

Okay.
Still problems.
Still sucking in the front of the MC a little bit, no-where near as bad as the original MC.
Could it just be the Hawk HPS pads are REALLY shit and have next to no stopping power when cold? Cause I reckon I could pull up better by cutting a hole in the floor and putting my feet out of it.

on another note, can anyone ONE HUNDRED PERCENT CONFIRM that these are DEFINITELY TWIN TURBO tie rod ends?
2 OUTER Tie Rod End Set For MITSUBISHI 3000GT 91-99 GTO | eBay (http://www.ebay.com.au/itm/2-OUTER-Tie-Rod-End-Set-MITSUBISHI-3000GT-91-99-GTO-/180559527895?pt=AU_Car_Parts_Accessories&hash=item2a0a2fbfd7)

Just waiting my bendix pads to arrive and i'll go from there. Hope it's just a pad issue.
I've bled the lines F and rear 675 times
taken the front calipers apart, cleaned all bores and pistons up, re-lubed them up and back together
another MC
could be another faulty MC since it is 2nd hand...eh.....dunno what to do now.

[GTOJOE]

Since all GTOs are AWD and have the same braking system I would assume things like the tie rod ends are the same as well.... Use ASA/CAPS to look up the part number for a TT and for an NA and see if they match. I suspect they will.

[TUFFTR]

I just dont have CAPS.....could you look up the P/N for an N/A GTO? I am positive they are different. the ends of my N/A ones (although for a magna same rack) are longer, and thinner, thus to get them to seat properly in the knuckle, they have to go down further on the tid rod end, squashing the boot to all buggery (grease is now everywhere cause of it) and had to stack up the thread with washers to bring the castle nut up to the holes in the thread!
oh the joys. Meh might just get these ebay ones, will be better then what I have now...

[GTOJOE]

Just checked ASA and ALL GTOs use the same part so go for your life.

If you don't have CAPS [replaced by ASA] I posted instructions on how to get it on here.

http://www.3sgto.org/f2/mitsubishi-asa-jdm-usdm-346.html

[TUFFTR]

So hmm.....how long to 'bed' pads in? Ive done about 500k's now, still piss poor braking and still the rotor face is dirty.
Alas, the MC is still pushing up some fluid. There is a good chance of course this MC is buggered too....how hard can this be to diagnose?
Does it need a proportioning valve installed? considering it's just 1 line direct to each caliper from the MC?
sigh.

[GTOJOE]

GTOs all have either a prop valve or ABS so I would say yes you should have one.

[TUFFTR]

GTOs all have either a prop valve or ABS so I would say yes you should have one.

Just started thinking that now. Fantastic I can see this chewing up all my money.
Never thought about it but even in the magnas in ABS models which use the twin piston calipers have a prop valve.
SO, next port of call, 2nd hand one ok to use?

[GTOJOE]

Yeah just grap one of a Magna i recon. As long as it looks clean and the brake fluid is clean. I assumed yours would have had one already.....

[TUFFTR]

Yeah just grap one of a Magna i recon. As long as it looks clean and the brake fluid is clean. I assumed yours would have had one already.....

There is a positive in this. I can now use one off a 2005 magnas which means for the $30 for a MC I basically get a brand fkn new one. Yeah I bench bleed the MC's before they go on the car anyway.
I'll be heading to the wreckers tomorrow so I guess I'll be stocking up on parts.
I better be able to do this engine in or else i am going to be PISSSSSSSED off.

And yeah - something I overlooked. I think this has been the issue all along as not many people really touch the base base model magna's let alone put 3000gt brakes on em...argh.