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ABS Master vs Non-ABS Master, What is the Difference?

S

sjulier

Member
Joined
Nov 20, 2013
Location
Hamden CT
Due to the discontinuation of brake master cylinder with ABS part 8251131 I am starting this topic. What is the difference between a master with and without ABS? Does a work around exist using a non-ABS master on an ABS system?

Thanks in advance for your constructive comments!

Sam
 
Not previously mentioned: this part number fits 90-93 240. It's maybe available, just not from Volvo. Look for remanufactured.

Interchange:
ATE 03.2022 - 2002.3
A.B.S. 41142
Bendix 132706B
Volvo 3530972
Volvo 8602015
PEX 2.22.362

Bendix 132706B fits 1974-1993 240
Girling 4006188
TRW PMH188
 
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lummert said:
Not previously mentioned: this part number fits 90-93 240. It's maybe available, just not from Volvo. Look for remanufactured.

Interchange:
ATE 03.2022 - 2002.3
A.B.S. 41142
Bendix 132706B
Volvo 3530972
Volvo 8602015
PEX 2.22.362

Bendix 132706B fits 1974-1993 240
Girling 4006188
TRW PMH188
Click to expand...

None of these parts are available.

Sam
 
The 'work around' is to find one in the junkyard like any true turbobricker, or beg in wanted, and go on down the road.

Or continue on with your car up on jackstands?
 
My mc on my 92 245 has failed. Can't find replacement online.

Differences:
The online pics show ABS mc has three line ports, 1 on either side of barrel and one on tip. The non-ABS mc has 2 ports, 1 on right (passenger) side of barrel and 1 on tip. Specs say threads are M10?1 on both types. I cant tell if other dimensions are the same to allow bolt up and interchange of the reservoir.

Oddly, the ABS mc on my car has the 3rd port (on left/drivercside of barrel) plugged/capped with a bolt. Only the 2 ports which match a non-ABS mc are in use, and they are plumbed to the ABS pump. The pump has 5 lines total, 2 pairs and 1 by itself. The car has been this way the entire time Ive owned it. The abs was nonfunctional initially, but some years ago I replaced the abs computer and fuse and it revived, or at least I thought so. The abs self tests, and vibrates/pulses under emergency braking conditions, so I assumed I had abs. Now Im not so sure, since that 3rd port is plugged/capped off.

I might be able to find a used abs mc locally, but if not will try the nonabs 2-port version and see what happens. Car is bricked until I find a solution.

Has anyone figured out a bolt on substitute?
 
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John V said:
Well you better look it up..
Click to expand...

oh, something you don't know? :-P
I guess I shall since no one here seems to know.

Im assuming they are different since the abs has a single line system and the non abs has dual lines. Front calipers on abs have single bleeder and non has two. Then its the piston caliper sizes would be why the master is different.
 
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Thank you. I presume the larger abs bore is so that it delivers more line pressure?
And thus, using a nonabs master on an abs car would result in weaker braking force, thus longer braking distance?
Do yall think this would be so unsafe as to not risk it?
 
Raybestos lists the MK1937 as the mc repair kit for a 1991- 1992 240 (1993 doesnt show a repair kit). Rockauto lists it at $43.99. I havent found specific bore dimensions to validate that its the right one, but is listed by the mfr for this vehicle.

EDIT: I just tried to buy one, but Rockauto said it is not currently available and has been removed from my cart.
 
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A larger bore diameter will deliver less pressure, not more. I'm sure there's a reason for the change in bore size for ABS brakes, probably having to do with the lack of proportioning valves.

The MK1937 kit is listed as fitting 240's all the way back to '75, so I don't think that's the right kit for an ABS master.
 
15/16 f/r works for my 88 765. But the 1-1/6 f/r that I tried was too large. Too large = rock hard pedal, not safe.

Edit: 1999 Ford Ranger master cylinder installed in my 88 765 has a 1-1/16" bore front and rear. Anything bigger is too big.
 
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lummert said:
15/16 f/r works for my 88 765. But the 1-1/6 f/r that I tried was too large. Too large = rock hard pedal, not safe.
Click to expand...


I don't understand what youre saying, what is f/r? Im racking my brain trying to figure it out and failing, lol.

Also, I think youre saying that too large a mc bore would mean hard pedal, unsafe.

The NLA abs mc has a larger bore than non-abs, so we would get extra line pressure with a substitution of the non-abs, smaller, mc. Maybe a softer pedal feel?
 
I obtained a used abs mc from the picknpull off a '92 244. That cars line configuration was the same, only the two ports were in use on the abs mc, with the 3rd capped with a bolt just like mine. The mc is ancient looking like mine, not a recent replacement, but I figure I'll give it a try, what the hell. If I'm lucky itll work until someone makes/remans a better choice.
 
Marauder03 said:
I don't understand what youre saying, what is f/r? Im racking my brain trying to figure it out and failing, lol.

Also, I think youre saying that too large a mc bore would mean hard pedal, unsafe.

The NLA abs mc has a larger bore than non-abs, so we would get extra line pressure with a substitution of the non-abs, smaller, mc. Maybe a softer pedal feel?
Click to expand...

The master cylinder bore is 15/16" front and rear.

Went back to look at the specs of the 1999 Ford Ranger master cylinder that I swapped into my 88 765. Bore is 1-1/16". When I tried a similar master cylinder from a Ford F-150 with 1-1/4" bore that was when I experienced a rock hard pedal with very little stopping power.
 
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I got lucky, the old abs mc I found at the yard was still good, so my 245 is back on the road. I did not try a non-abs mc, so we still dont know if it is workable.
 
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