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Remove reducing valve to rear brakes?

rijk

rijk

Member
Joined
Apr 14, 2004
Location
Netherlands
Have installed V70R Brembo calipers and rotors with V70R stock pads f/r on my '93 960, together with new Mustang m/cyl. with extended rod. Installed a proportioning valve in the rear brake line. But since there is a stock reducing valve for the rear brakes, I ask myself if that should be removed or not. And what effect will this all have on the stock ABS. Anybody familiar with this?

 
Personally I don't know about a pressure reducing valve at the brake lines to the rear at a 940/960

There will be a pressure limiting valve at cars without ABS....

And the line where you mount your valve in is the most stupid, sorry.

If you want to reduce pressure to the rear you should mount the valve between master cylinder and ABS, and never ever AFTER THE ABS.
Do you have a little knowledge about pressure peak at cars with ABS if the system is regulating full?
The only solution to balance between the front and the rear is a balance beam system. Made for racecars. ....
Good luck, Kay
 
The device with 4 brake lines is not a proportion valve, it is a pressure imbalance switch. The wire turns on the red light on the dash.
If it has ABS that part should not be there.
 
The car has ABS and a reducing valve (pic)

n4rWRFQ.png
 
The image is blocked on my work computer, and on my phone it won't let me expand it. As for the diagram, and more importantly for your car, if there is no wire and it does limit max pressure (which is what your aftermarket proportion valve does), of course you don't need 2 of them. So if you want, remove the in/out lines from that block(the one going to the rear input on the ABS unit), and install the aftermarket unit there. No-brainer.
My alldata diagram info could be wrong, but I can't tell from here. And personally, I would see how it does with no pressure cap on the rear. If it triggers ABS too often, then fix the "problem".
 
Your pic shows 4 lines from #12, that looks like a pressure imbalance switch not a pressure reducing valve. Why would the front lines go into a pressure reducing valve for the rears?
 
A different type of reducing valve was added to both ABS and non-ABS brakes in '92. The reason the front brake circuit goes to the valve is because there's a safety feature built into the valve that allows full pressure to the rear brakes if the front circuit fails.

ABSReducingValve.jpg


open-uri20150714-9168-1arm3k4.
 
hiperfauto said:
A different type of reducing valve was added to both ABS and non-ABS brakes in '92. The reason the front brake circuit goes to the valve is because there's a safety feature built into the valve that allows full pressure to the rear brakes if the front circuit fails.

ABSReducingValve.jpg


open-uri20150714-9168-1arm3k4.
Click to expand...

Thank you, I did learn something new again.
Good day :-)

I will have a closer look to the Volvo at this side of the pond.

IIRC still a limiting valve

If I find one I will do a test and open the stuff to understand more.

Have a nice day, Kay
 
If I can get my hands on one (chris sold his long ago) I'll do some pressure tests.
I also want to do tests on stepped master cylinders.
 
mikep said:
If I can get my hands on one (chris sold his long ago) I'll do some pressure tests.
I also want to do tests on stepped master cylinders.
Click to expand...

Isn't the '93 model year 960 nearly identical to the 940? I think it was '95 when they became different vehicles. We can always goof with my '91 if the '93 has already been cannibalized
 
mikep said:
So if you want, remove the in/out lines from that block(the one going to the rear input on the ABS unit), and install the aftermarket unit there. No-brainer.
My alldata diagram info could be wrong, but I can't tell from here. And personally, I would see how it does with no pressure cap on the rear. If it triggers ABS too often, then fix the "problem".
Click to expand...

Thanks. That is exactly the way the proportioning valve is connected now. Soon I will find out how that works.
 
ABS and reducing valve

mikep said:
The device with 4 brake lines is not a proportion valve, it is a pressure imbalance switch. The wire turns on the red light on the dash.
If it has ABS that part should not be there.
Click to expand...

My car has ABS and that - as you call it - pressure imbalance valve. Volvo itself calls it a reducing valve (#12 on the parts list). Anyway function is the same.
 
rijk said:
My car has ABS and that - as you call it - pressure imbalance valve. Volvo itself calls it a reducing valve (#12 on the parts list). Anyway function is the same.
Click to expand...

No, the function is completely different.

A reducing valve would 'reduce' pressure. The balancing valve is designed to retain pressure in the other half of the system when one half fails.

As noted above, it's a safety feature and does nothing unless one of your brake circuits fails.
 
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