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non ABS prop valve from 91 galant


belize1334
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Galant VR-4 org Post #: 573642 posted 12/07/07 12:22 PM     Remind Me!  Send Private Message   Edit Post      
I found a prop valve at a Pick-N-Pull on a 91(ish) non-ABS FWD n/t Galant. I'm curious to know how the bias compares to our stock system (including the abs unit) vs. the 1G prop valve. I know that with the 1G there's a slight issue of the rears locking up too soon and I'm thinking that this was made for our weight balance and might eliminate that problem. Does anyone have info on this?



Roger B. Scott
'91 Belize Green

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Galant VR-4 org Post #: 573645 posted 12/07/07 12:26 PM     Remind Me!  Send Private Message   Edit Post      
There is info on a lot of the prop valves on RRE's site, but I don't recall seeing any NT prop valves listed. I've often asked this same question and it seems to piss a few people on here off as they don't seem to think it matters. Good luck in your travels



-Jeff
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Dialcaliper
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Galant VR-4 org Post #: 573854 posted 12/07/07 03:10 PM     Remind Me!  Send Private Message   Edit Post      
It's probably a bit better for the front/rear bias, but the weight distribution seems to be about the same for both (60/40) so don't quote me on that.

If your bias is a little off, and you don't want to shell out time and effort on an adjustable valve or fitting different rotors, you can compensate by finding some slightly less grippy rear pads (or grippier front pads). It won't really affect your stopping power, just the required pedal pressure, since locking the rears is far worse for your braking.



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belize1334
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Galant VR-4 org Post #: 573860 posted 12/07/07 03:13 PM     Remind Me!  Send Private Message   Edit Post      
The main concern I have is that I don't remember if the donor car had rear disks or rear drums. If it's drums, then I can imagine that the rear pressure may be very different then it would be for disks. I don't know that this is true but I'm just speculating that it's a possibility.



Roger B. Scott
'91 Belize Green

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14u2nV
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Galant VR-4 org Post #: 573893 posted 12/07/07 03:36 PM     Remind Me!  Send Private Message   Edit Post      
Only vr4 and Gs galants had rear disk IIRC. I'm using a non-abs from a 92 gs, and I'd almost swear the fronts lock just slightly ahead of the rears.

*GSX probably had disk too, but I've never seen one in person.



~Kenneth Brian
"Censorship offends me" ~Author Unknown



Edited by 14u2nV (12/07/07 03:38 PM)

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IslandVr4
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Galant VR-4 org Post #: 573916 posted 12/07/07 04:03 PM     Remind Me!  Send Private Message   Edit Post      
I have a prop valve from a plain jane galant in mine, just the other night when a turn snuck up on me & I laid into the brakes, rears started locking. Based on that alone I'm on the hunt for one from a 4wheel disk car.

It works & under normal conditions its fine but I didn't like the feeling of the car wanting to rotate under me.

My 2psi

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toybreaker Galant VR4.org Moderator
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Galant VR-4 org Post #: 574072 posted 12/07/07 10:03 PM     Remind Me!  Send Private Message   Edit Post      
I'm not even close to an expert on this subject, but I'm working this problem on my own car, so I've been thinking about this recently.

The question of possibly using a drum brake prop. valve brought back a lesson, hard learned, from back in the day.

Vehicles equipped with front disc, and rear drum brakes often use a metering hold off valve in their braking systems. It's generally co-located in the proportioning valve housing.

It has multiple purposes, but the main one is to allow the front and rear brakes to energise at the same time. Without it, the front disc brakes would apply sooner than the rear drum brakes.

The why of that goes like this...

When you press on the brake pedal, the caliper pistons move 1 for 1 with brake presssure.

Rear drum brakes, however, have strong springs on the brake shoes that return them to the rest position when you release the brakes. These springs will resist the motion of the shoes at light pedal pressures. This will delay the application of the rear brakes. In fact, at light pedal pressures, only the front calipers would be doing any work, because the rears would have to overcome that spring pressure to move enough to contact the drum.

Sooooo, on drum brake equipped cars, there's a dingus in the prop valve that would time the system, and adjust the front/rear work levels at light pedal pressures.

The problem is when you use that style prop/metering hold off valve on a vehicle that has rear discs...it will make the rear brakes uber sensitive at low pedal pressures.

For those of us that do a lot of winter/snow driving, that spells trouble with a capital "OH SHIT" on ice at high speeds.

My own experience has also been that it will hold some ~small~ amount of line pressure on the rear circuit.

It only holds a couple of psi, (certainly less than ten psi), so it's hardly noticeable, however, it's there, 24/7...especially when the system is warm.

Backstory, (for those who care ). I found this out the hard way back in the day playing z-cars. The rear disc brake conversions we were doing would eat rear pads. In addition, the rears would run hotter, and stay warmer longer than one would expect. The front/rear balance was ~adequate~, but we ate rear pads any time we really pounded on the cars. (Keep in mind, these were v8 swapped nissan z cars, we drive hard, and we live in the mountains)

We didn't have the intraweb back in the day, so we had to figure shit like this out ourselves.

I used to call the various suppliers, manufacturers, and anyone who would listen to ask questions, and every now and then we would get lucky. One day, I was abusing a retired GM project engineer about doing a conversion using corvette goodies, and he turned me onto a retired Lock-heed engineer in our area that helped design the systems.

He asked to see the set-up we were running, and put some really cool brake pressure gauges where the bleeders go and we went for a ride. Yep, you guessed it, ~4 psi , (with the pedal released), ALL the time to the rear brakes.

It was an education, listening to that man! (Sadly, he's passed, 8 years ago... )

One thing he did teach me is to understand the whole system before I started tampering with it.

I have tried to follow his sage advice.

I'm doing the abs delete on my own car, and I had a bunch 'o questions as well.

(searching the topic just gave me a headache, as the information contridicts itself many times in the threads I found, both here, and elsewhere on the intraweb.... )

Has anyone here ever actually measured the brake pressure, the knee point, and the actual split from the factory prop valves available?

I see a lot of people describing front/rear balance as a function of lock-up.

There's so many variables in the equation, that I'm not so sure that's a good definition of the actual hydraulic pressure settings.

The front/rear brake pad materials, tires, suspension settings, battery relocations, road surface etc. will have a profound effect on the effective brake balance. It's one part brake leverage, one part tire adhesion, one part road surface. (Etc) These all effect weight transfer.

Intuitively we can see with better tires/road surfaces, bigger front brakes etc, we get more weight transfer to the fronts, and the rears will lock more easily/sooner.

Change one variable, and you change that threshold where the rears will lock first.

For example, even the grade of the road effects brake balance. I find myself hazing the rears going downhill when I'm late for work, but going home, uphill, same road, same car, same driving style, I never hear the rears even when I brake up to, and past the apex. (Boost/Brake...oh...yea.. ...guilty!)

I'd love to have a thread in the how to's that had empirical evidence of what works on these cars!

On a side note, I've been looking at the various master cylinder choices, and, as a point of interest, Mitsubishi has a different set of internals in the non abs version of these master cylinders. Anybody know why?

Oh, yea, the original topic...( ) I'm running a 1g, awd, non abs prop valve in my 92 vr4, and it works ~reasonably well, in most circumstances, and I'm pretty particular about things like that.

Still.... I'd love just a schosche more rear bias...

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Wizardawd
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Galant VR-4 org Post #: 574105 posted 12/07/07 11:31 PM     Remind Me!  Send Private Message   Edit Post      
Split Points: Year FWD/AWD
90-91 All 4200/3700
90-91 All w/ABS 4200/3700
92-93 All, 94 NT 2500/3500
92 All, 93-94 NT w/ABS 2500/3500
94 T ???/???
93-94 T w/ABS 2500/3500
91-92 GVR4 N/A/5200
95-99 ???/???

Taken from that wonderful site....www.vfaq.com

Higher number means more front bias.

Wiz



598/1000 Nile Black
12/2000 Nile Black
1995 Montero SR
1997 Talon Tsi AWD Auto


Edited by Wizardawd (12/07/07 11:32 PM)

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toybreaker Galant VR4.org Moderator
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Galant VR-4 org Post #: 574107 posted 12/07/07 11:41 PM     Remind Me!  Send Private Message   Edit Post      
^^^DOH!

Thanks for the info!



the bitterness of low quality remains long after the temporary joy of a low price has faded


Edited by Toybreaker (12/07/07 11:42 PM)

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belize1334
well bread and nobly conceived
1334/2000


Galant VR-4 org Post #: 574121 posted 12/08/07 01:26 AM     Remind Me!  Send Private Message   Edit Post      
I looked at those but I thought they only referenced the TELs (aside from the GVR4 of course).



Roger B. Scott
'91 Belize Green

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Dialcaliper
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Galant VR-4 org Post #: 574122 posted 12/08/07 01:29 AM     Remind Me!  Send Private Message   Edit Post      
That's some pretty deep stuff Toybreaker - I didn't remember than not all of the galants weren't disc brakes.

I'd bet that the lower bias on the 1G DSMs has only a little to do with the brake distribution and more to do with the single piston front calipers? Does anyone know the actual ratio on the prop valve above the split point?

I think the units there are kilopascals, which makes the VR-4 come out to 752 psi, which might be similar to the prop valve used in the 3000GT VR4 Spyder? That's probably going out on a limb though, since who knows on the rear reduction

The DSM numbers come out to

90-91 FWD 4200 = 609psi
90-91 AWD 3700 = 536psi
92-94 FWD 2500 = 362psi
92-93 AWD 3500 = 507psi

from click
3000GT VR-4 (533-604psi split, 34-42% rear reduction)
3000GT VR-4 Spyder (704-775psi split, 23-34% rear reduction)
3000GT VR-4 (Australia) (391-462psi split, 25% rear reduction)

Anyone care to interpret?



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Wizardawd
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Galant VR-4 org Post #: 574129 posted 12/08/07 05:35 AM     Remind Me!  Send Private Message   Edit Post      
Why not a NT 3000GT/Stealth ES/RT? The weight of the car is similar with similar weight distribution and have the same dual piston calipers up front with similar calipers in the rear as far as piston size goes. Anyone find the numbers for that?

Wiz



598/1000 Nile Black
12/2000 Nile Black
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IslandVr4
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Galant VR-4 org Post #: 574307 posted 12/08/07 07:33 PM     Remind Me!  Send Private Message   Edit Post      
Hey, I didn't think about the 3kgt. Is the valve physicly the same, I would be happy to pop one in & go out to my road test area & see what I can make happen.

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Dialcaliper
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Galant VR-4 org Post #: 582095 posted 12/27/07 10:41 PM     Remind Me!  Send Private Message   Edit Post      
I was tooling through the Galant factory service manual, and I stumbled across some actual numbers, so I decided to do some sleuthing.

Proportioning valves:

AWD, w/ and w/o ABS:
Split Point: 740 psi
Decompression ratio: 0.4

89-91 FWD, ABS w discs and Non-ABS w/ rear drums:
Split Point: 597 psi
Decompression ratio: 0.3

Other Galant FWD models:
92 and later SOHC: 597, 0.4
92 and later DOHC 526, 0.3

It's important to note two things.
All FWD Galants had the same prop valve, drums or discs. Drum models have a separate "delay" valve toward the rear of the car.
A non-ABS valve from a GSX (if it exists?) would be a perfect match for a VR-4

GGSX Prop Valve from CAPS:
Valve, Brake Fluid Proportioning
MB618565 replaced by MB699654 (ABS valve is MB618567/MB699656)

From JNZ Tuning:
MB699654, Pressure metering valve, galant, 4wd, w/o abs, from 10/90
Price: $55.95


All of the prop valves seem to operate in the same fashion - Master cylinder feeds in the front either directly or through the ABS modulator. The top two outlets (as mounted) are throttled for the rear brakes.

Now the only difference between the ABS and non ABS prop valves seems to be that the H-casing is drilled and tapped to accept front brake lines on the bottom half. These see full pressure anyway, so it's nothing more than an extra hole.

Disclaimer - it would probably work to drill and tap the valve for front brake lines, but do so at your own risk...

In short, the valve works in identical fashion to the aftermarket adjustable type, which just have an adjustable split point. The Tilton valves have a 3:1 ratio (0.33), but I'm not sure about the Wilwood valves.

For reference, these may have been stated above, but here's from the service manual:
90-91 FWD: 597, 0.3
90-91 AWD: 526, 0.3

92-94 N/T: 597, 0.3
92-94 T : 363, 0.25
92-94 AWD: 508, 0.25

All 2G DSMs have a 0.25 valve, but no split points are listed. The 2G spyder service manual lists split points of 320-391psi for nonABS and 391-462psi for ABS. Ratio is not listed, but based on the numbers for the prop valve test, I think Non-abs is 0.25 and ABS is 0.3.

3000GT All appear to have a valve that's 533-604 split point and 0.37 ratio, but all models have a system that's integrated with the ABS unit.

From the look of it, all of the DSM prop valves are biased much more towards the front brakes than the Galant. This would imply that you'd need a rather large rear brake upgrade in order to use one properly. None of the other valves I could find seem to be quite so rear biased as the Galant.

It looks like the best options are to either put in a front biased brake setup and run a DSM valve, or work for a rear-biased setup with a SOHC Galant, which has the right proportioning, but a different split point (which would give the car a little front bias).

Why do service manuals progressively contain less inforation and assume people are less intelligent as time goes on?

If I get unlazy, I might put these numbers in a spreadsheet/graph to see what they look like actually look like relative to eachother. Unless someone else wants to.



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Edited by Dialcaliper (12/27/07 11:15 PM)

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14u2nV
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Galant VR-4 org Post #: 582097 posted 12/27/07 10:50 PM     Remind Me!  Send Private Message   Edit Post      
My 92 GS was FWD, all disk, non ABS. you don't have that listed. That's the valve that is in my Vr4 now, and works great.



~Kenneth Brian
"Censorship offends me" ~Author Unknown



Edited by 14u2nV (12/27/07 10:51 PM)

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Rausch Galant VR4.org Moderator
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Galant VR-4 org Post #: 582104 posted 12/27/07 11:00 PM     Remind Me!  Send Private Message   Edit Post      
^ I would assume that either way it's the same valve. ABS or not, Drum or disc. ...From what I read above.

They probably didn't list that combination specifically., as it most likely is not as common.



Rance lives here...
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belize1334
well bread and nobly conceived
1334/2000


Galant VR-4 org Post #: 582107 posted 12/27/07 11:05 PM     Remind Me!  Send Private Message   Edit Post      
Quote:



AWD, w/ and w/o ABS:
Split Point: 740 psi
Decompression ratio: 0.4

FWD, ABS w discs and Non-ABS w/ rear drums:
Split Point: 597 psi
Decompression ratio: 0.3

For reference, these may have been stated above, but here's from the service manual:
90-91 FWD: 597, 0.3
90-91 AWD: 526, 0.3

92-94 N/T: 597, 0.3
92-94 T : 363, 0.25
92-94 AWD: 508, 0.25






So if I'm reading this correctly, the AWD galants have the most front heavy brakes, followed by the FWD galants and earlyl DSMs and then lastly the later DSMs which have the most rear heavy brakes. In addition, the AWD galants have the highest split point, again followed by GWD galants and later model DSMs.

In application then. To put a FWD galant prop valve in, the rears would work harder than the fronts at low pressure, but the split point would come in earlier and after that the fronts would start working harder. This effect seems to be more dramatic as you go down the list, with the bias becoming more intense and the split point lower. It seems to me then, that if you can't get a AWD galant valve, and you don't want to mess with drilling and tapping the stock one, then one like the one I have (91 FWD non-abs rear drum Galant) is the best option as it's most similar to stock.



Roger B. Scott
'91 Belize Green

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Dialcaliper
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Galant VR-4 org Post #: 582114 posted 12/27/07 11:18 PM     Remind Me!  Send Private Message   Edit Post      
By the way, does anyone know the Stock VR-4 rear caliper piston diameter? I can't seem to find it anywhere, and I got distracted looking at all the prop valves.

Edit: Never mind, I finally found it
AD35P Caliper = 41.3mm piston (VR-4/GSX)
AD30P Caliper = 30.2mm piston (some FWD DSM's)



1269/2000 Summit White


Edited by Dialcaliper (12/28/07 04:53 AM)

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Dialcaliper
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Galant VR-4 org Post #: 582141 posted 12/28/07 04:36 AM     Remind Me!  Send Private Message   Edit Post      
Okay, here's a quick plot from excel, for anyone interested:

The differences are actually pretty subtle - The highest pressure I could find reference to in the service manual was 1300psi, and regardless of valve, The rear pressures all end up within about 150psi of eachother.

The only significant differences seem to be with the knee, which should match the brake pressure where the car begins to pitch. Otherwise, they basically converge. Under normal to heavy braking, All other valves will tend to bias the front brakes, except under very heavy braking with several of the DSM valves where it shifts rearward.

The only valve that has a major effect under heavy braking is the 92+ SOHC Galant Valve, which has more front bias.

None of the valves will really do anything towards fixing the front bias caused by upgrading the front brakes only, except maybe a DSM non-turbo (or older galant) valve. But only then under heavy braking.



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toybreaker Galant VR4.org Moderator
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Galant VR-4 org Post #: 582171 posted 12/28/07 08:19 AM     Remind Me!  Send Private Message   Edit Post      
Thank you very much for your research!

I especially appreciate your follow up on the metering hold off valve on the drum brake galants. They are *generally* co-located in the prop valve body. It's nice to see they aren't in the base galants, as that adds another choice to the list of suitable donors.

The excel graph is a very nice touch.




^Here's the prop valve/line layout for a a 3000gt, (notvr4) non abs system.



^And here's a 1g/galant without abs

The routings are subtly different, but do-able, especially if you're swapping out the master/fabbing new feed lines from the master cylinder.

(The lines from the master come in the front on the 1g/galant, and the bottom on the 3000.)

Is there any benefit to considering the 3000gt units?

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BoostedAWD91
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Galant VR-4 org Post #: 668666 posted 07/13/08 02:26 PM     Remind Me!  Send Private Message   Edit Post   
I just aquired a few non-abs Prop valves from non turbo 89-91 galants. Are these the correct vavles to use for the non abs conversion?



#815/2000- Lexus Pearl White


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