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Guest Message by DevFuse
 

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rear disc brake swap.


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27 replies to this topic

#1 jonas

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Posted 06 June 2006 - 07:11 PM

is '85 the last year rear discs would be interchangeable with my '84 wagon? i located wrecked '86 and '87 turbos w/ discs still on them.

#2 Johnnyboy

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Posted 06 June 2006 - 07:18 PM

Nah, you'll find any EA82 vehicle will suit. You may need to get a new flexible brake line, rather than use the old hardline part. see how you go.

#3 jonas

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Posted 06 June 2006 - 07:28 PM

schweet.

#4 TheSubaruJunkie

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Posted 06 June 2006 - 07:33 PM

Just make sure, if your '84 is a 4WD you get the rear disc's from another 4WD. If your '84 is 2WD, you will need to find a 2WD with rear disc's to use.

Other than that, any year will work.

-Brian

#5 jonas

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Posted 06 June 2006 - 08:18 PM

got it. thx.

#6 mellow65

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Posted 06 June 2006 - 09:54 PM

Ok not to thread jack here but it's on the same line of the rear disc swap. In all that I read about rear disc swaps i have never heard about the proportioning valve being swaped also. Is this not really needed or what?

#7 calebz

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Posted 06 June 2006 - 10:47 PM

Ok not to thread jack here but it's on the same line of the rear disc swap. In all that I read about rear disc swaps i have never heard about the proportioning valve being swaped also. Is this not really needed or what?


Nope. No need

#8 lastchance

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Posted 06 June 2006 - 11:56 PM

Remember when we talked about this Jon? It's way worth it! Good luck! :grin:

#9 TheSubaruJunkie

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Posted 07 June 2006 - 12:02 AM

I dont think EA82T's have this valve you speak of. Maybe im wrong, but i know its not needed to do the swap.

Check out the USRM for the details.

-Brian

#10 mellow65

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Posted 07 June 2006 - 01:14 AM

Very cool, I just got a running DL wagon for $100. Sweet now I'm on the search for rear discs. Thanks

#11 Loyale 2.7 Turbo

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Posted 07 June 2006 - 08:31 AM



Very Nice! :)

I just wanna see pics of it when it`s done, could you post them here?



#12 PoorManzImpreza

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Posted 07 June 2006 - 10:50 AM

just by the way..all ea82s have a valve that varies pressure to the rear brake assemblies based on vehicle load. 'g load sensing valve' as its termed...I dunno how much it varies pressure by..but it does seem to differ from model/year and whether the car is 4wd or 2wd..

#13 carfreak85

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Posted 07 June 2006 - 01:11 PM

just by the way..all ea82s have a valve that varies pressure to the rear brake assemblies based on vehicle load. 'g load sensing valve' as its termed...I dunno how much it varies pressure by..but it does seem to differ from model/year and whether the car is 4wd or 2wd..


I've never heard of this valve. Perhaps you're confusing it with the hill holder?

#14 GeneralDisorder

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Posted 07 June 2006 - 02:26 PM

If you are putting the discs on an EA81 then yes - you need the valve. EA81's have no proportioning control at all. I've said it before, but people on here refuse to listen. I did a skid test with my Brat (not lifted) and the difference is pretty scary without the valve.

There's really a lot more differences than people here realize - for example there are two sizes of rear discs - wagon/coupe and sedan. For some reason the sedan got smaller rear calipers. This also means different proportioning control as hinted at above....

GD

#15 carfreak85

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Posted 07 June 2006 - 04:25 PM

Thats very odd. I seem to remember a thread where someone was very worried about the need for a proportioning valve, but all the senior members assured this member that they had checked the parts catalogs and that there were no proportioning valves in the entire system. Oh, and I have rear discs on my EA81 wagon and emergency braking ins't scary at all, in fact the braking (With or without the valve) is 10x better than with the old drums in back. I don't think I'm going to install this mythical valve for the simple reason that it seems unnecessary to the functioning of the brake system.

#16 mikeshoup

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Posted 07 June 2006 - 05:10 PM

There definitely is a proportioning valve. My 1988 XT FSM shows one for both XT6s and XT 4cyls. My Haynes manual also shows it, but neglects to say which models it is on.

Of course with anything, results will vary. Some people may feel after converting to rear disks that the proportioning valve is needed, others will say its not.

#17 Caboobaroo

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Posted 07 June 2006 - 06:38 PM

I did a rear disc swap on a '84 Brat and in the snow, the rear end locked up before the ftront, thus making it slide all sideways. I had to be careful.

#18 mellow65

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Posted 07 June 2006 - 07:01 PM

I did a rear disc swap on a '84 Brat and in the snow, the rear end locked up before the ftront, thus making it slide all sideways. I had to be careful.



And this is what the proportioning valve stops. Instead of send equal pressure to all four wheels it allows the front to start stopping first then letting pressure to the rear. And in something like a brat I could see how having one would be nice because the rear end is so light, but I'm sure in a wagon it wouldn't be as bad because of all the weight.

#19 GeneralDisorder

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Posted 07 June 2006 - 07:05 PM

I did a rear disc swap on a '84 Brat and in the snow, the rear end locked up before the ftront, thus making it slide all sideways. I had to be careful.


We have a winner! That's exactly what mine did - only on wet pavement. I installed the valve and she brakes 100% straight.

GD

#20 Petersubaru

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Posted 07 June 2006 - 08:04 PM

the haynes manual can be a bit confusing because it is published in england and the early loyales all had proportioning valves over there unlike my canadian loyale ('86) which does not have a valve and according to the subaru dealer did install one until the '92 models..the rears lock up in the winter and I don't drive it anymore because the rear can swing around to the front...it is panic brakeing that we need to be concerned with here and control is really needed under these conditions..without the proportioning valve you just don't have it.......

There definitely is a proportioning valve. My 1988 XT FSM shows one for both XT6s and XT 4cyls. My Haynes manual also shows it, but neglects to say which models it is on.

Of course with anything, results will vary. Some people may feel after converting to rear disks that the proportioning valve is needed, others will say its not.



#21 Petersubaru

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Posted 07 June 2006 - 08:05 PM

where did you get the valve...

We have a winner! That's exactly what mine did - only on wet pavement. I installed the valve and she brakes 100% straight.

GD



#22 GeneralDisorder

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Posted 07 June 2006 - 08:50 PM

Same car I got the brakes from. 88 FT4WD Turbo Automatic Sedan IIRC.

My 86 carbed sedan has one too - even with the rear drums. I'm sure it's a different "proportion" but it's there. EA81's (in the states) never had any form of proportioning control, but the front discs are much smaller as are the calipers. I'm guessing the fact the rear drums are not very powerful (and usually out of adjustment), and the small discs they just don't need them.

GD

#23 PoorManzImpreza

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Posted 08 June 2006 - 12:34 AM

If you are putting the discs on an EA81 then yes - you need the valve. EA81's have no proportioning control at all. I've said it before, but people on here refuse to listen. I did a skid test with my Brat (not lifted) and the difference is pretty scary without the valve.

There's really a lot more differences than people here realize - for example there are two sizes of rear discs - wagon/coupe and sedan. For some reason the sedan got smaller rear calipers. This also means different proportioning control as hinted at above....

GD


yup I figured this out when I got a rebuild kit for my drums (when I had them) and the parts guy asked me if I had a SW or a sedan I said wagon and asked him why..sedan used 11/16" wheel cyl. and wagon uses 3/4"
so figuring that the same is true for rear discs I ordered the part from 1stsubaru for a wagon and they shipped it, I strip off a rear caliper take everything apart only to go WTF? sent me the wrong rebuild kit..2 small..so I go to local dealer grab the parts book and sure enough they sent me the wrong part..it seems their parts database has the wrong parts number associated with wagons..so fair warning for those buying kits..and I couldn't return it cuz I'm not exactly local lol..

if one looks under the back of an ea82 where the fuel lines enter the body of the car you'll see the 'g load sensing' proprtioning valve..

#24 Petersubaru

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Posted 08 June 2006 - 06:51 AM

my 86 is a Wagen 4wdr and I know that the replacement discs have to come from another 4wdr vehicle...can I use discs and the proportioning valve from a sedan or am I only stuck to useing the discs/pro. valve from another wagen ..I am seeking to make this change over as proper as possible

#25 GeneralDisorder

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Posted 08 June 2006 - 08:25 AM

my 86 is a Wagen 4wdr and I know that the replacement discs have to come from another 4wdr vehicle...can I use discs and the proportioning valve from a sedan or am I only stuck to useing the discs/pro. valve from another wagen ..I am seeking to make this change over as proper as possible


Wagon's are MUCH, MUCH more common (with discs), so likely that's what you'll get anyway.

I really doubt it would make that much difference on the EA82 - even the drums have the valve (different proportion, but at least it has one), so the phenomena is not nearly as pronounced. If you want to be safe just get the valve from whatever car you get the discs from.

GD




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