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  1. #1

    Default 7.5 in rear axle brake line questions

    I'm converting my 84 GT 350 5.0, with t-5 and 7.5 in rear end to dual exhaust. I'm struggling a bit with relocating the brake lines. I want to keep the 7.5 in rear. I ordered the rear axle line for an 85 V8 with 7.5 in rear end thinking that would allow me to simply swap the lines (http://www.classictube.com/power-dis...-7-5-axle.html) using the hose and bracket below. I only ordered the rear axle hard lines not the intermediate lines. I assumed this would allow me to move the connection point to the differential. I was surprised to see that the real axle lines I ordered are exactly the same as the my current lines and would sill connect on the passenger side. I though they sent me the wrong lines but I called classic tube and they said those were correct for an 85 with a V-8 and 7.5 in rear.

    I planned to use this rear differential brake hose (https://www.americanmuscle.com/rear-...hose-8795.html) and this upper brake hose bracket (https://lmr.com/item/LRS-2073BRKT/mu...-bracket-86-93) to connect the intermediate lines to the axle lines at the differential.

    I was going to bend the intermediate line to the center of the car as suggested in this post (http://vb.foureyedpride.com/showthre...e-Line-Routing)

    Here are my questions:

    1) Are hard axle lines for an 85 GT with V8 and 7.5 in rear the same as an 84? I would have thought they were different due to 85''s having dual exhaust from the cat back.

    2) Rather than use 85 lines could I order the lines from an 86 even though that would be for an 8.8 rear end rather than 7.5?

    3) Can I use the brake hose and bracket above to connect to 85 or 86 hard lines.

    4) Rather than bend my current intermediate line could/should I order the intermediate line from an 86? Note I do have maximum motor sports sub frame connectors welded in.

    This is the last issue I need to workout to complete the conversion. Thanks in advance for the help.
    Last edited by Crimson_Stang; 07-29-2018 at 09:41 AM.
    Have:
    84 GT 350 Anny 5.0
    05 F-150 Super Crew
    08 Saturn Outlook
    Had:
    00 Nissan Frontier
    97 Gand Prix GTP (Supercharged)
    87 Audi Coupe GT
    84 Mustang L 3.8

  2. #2
    FEP Super Member erratic50's Avatar
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    I would make it like the 86. Less trouble with future upgrades.

  3. #3

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    I just don’t have a lot of interest in changing out to an 8.8 rear end right now. I’d like to keep the 7.5, but would use the 8.8 hard lines if they would fit even with minor modifications.


    Sent from my iPhone using Tapatalk
    Have:
    84 GT 350 Anny 5.0
    05 F-150 Super Crew
    08 Saturn Outlook
    Had:
    00 Nissan Frontier
    97 Gand Prix GTP (Supercharged)
    87 Audi Coupe GT
    84 Mustang L 3.8

  4. #4

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    So could I use the hard lines from an 86 with 8.8 rear end on an 7.5 rear end?


    Sent from my iPhone using Tapatalk
    Have:
    84 GT 350 Anny 5.0
    05 F-150 Super Crew
    08 Saturn Outlook
    Had:
    00 Nissan Frontier
    97 Gand Prix GTP (Supercharged)
    87 Audi Coupe GT
    84 Mustang L 3.8

  5. #5
    FEP Super Member erratic50's Avatar
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    Dec 2016
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    Nebraska
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    The lines from the 86 8.8 will fit the 7.5 but the line from the rear end to the body is different and the fitting location on the body and the fitting itself are different.

    easy mod. Necessary for dual exhaust

  6. #6

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    I converted my 85 to dual exhaust when I swapped from the 2.3 to a 347. I didn't have to make any modifications to the brake lines. All I did was on the passenger side for new hanger I mounted the hanger and was still able to put the brake hose bracket with it. The bolt for the new hanger I ordered was long enough, BUT I dumped the exhaust before the rear end. If one was going the whole way with tailpipes is that when new lines and what not are required?
    Last edited by chevelle21; 08-03-2018 at 03:47 PM.

  7. #7
    FEP Member Dadsccat's Avatar
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    Oct 2014
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    Niagara Falls , Ontario, Canada
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    477

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    I used an exhaust system for an 86 and 86 brake lines to convert but had to modify the coupling on the rear axle the splits the line coming from the master to the rear wheels. Also changed the transmission crossmember. Everything worked fine.
    Shawn


    Currently in the stable:
    83 Capri RS Crimson Cat
    90 7 UP Mustang
    87 Mustang GT
    83 Porsche 928S
    69 Thunderbird Landau
    65 Cadillac Calais 4DR Hardtop
    02 Thunderbird

  8. #8

    Default 7.5 in rear axle brake line questions

    OK made some progress but also had some setbacks. Evidently the rear differential brake hose ([url]https://www.americanmuscle.com/rear-diff-brake-hose-8795.html) that I planned to use will not work. I guess I should and listened when it said it fits 87 - 93. It looks like RockAuto has one specifically for an 85 with 7.5 in rear end (https://www.rockauto.com/en/moreinfo...430161&jsn=615). I'm hoping this will fit. If nothing else I'll use the bracket and keep the hose off the first one I ordered. I know it fits the axel hard lines and the upper brake hose bracket.

    Also I ordered lines directly from Classic Tube. I got the axle hard lines and intermediate lines for an 86. The axle hard lines seem to fit fine, but the intermediate line is exactly like the intermediate line I already had. (See picture below). It does not go to the middle of the car to connect to the upper break hose bracket. I assume they sent me the line for a V6 with a single exhaust. Shouldn't the intermediate line for an 86 V8 Dual Exhaust be different than an 84 V8 Single Exhaust or is there another line that I should be asking about?

    Name:  Breakline Picture.JPG
Views: 295
Size:  32.3 KB
    Last edited by Crimson_Stang; 08-11-2018 at 10:34 PM.
    Have:
    84 GT 350 Anny 5.0
    05 F-150 Super Crew
    08 Saturn Outlook
    Had:
    00 Nissan Frontier
    97 Gand Prix GTP (Supercharged)
    87 Audi Coupe GT
    84 Mustang L 3.8

  9. #9

    Default 7.5 in rear axle brake line questions

    OK...some good news. The brake hose bracket for the 85 that I got from Rock Auto is a perfect fit and mates right up to the rear axel hard lines as well as the upper brake hose bracket that I got from LMR.

    Now for the bad news. Classic Tube is insisting that they sent me the correct intermediate lines. I confirmed tonight that this line is exactly like my original line. Here's a picture on this new line "mock up" installed. It runs right to the point where my original brake hose bracket was on the passage side. Name:  Brake Line.JPG
Views: 281
Size:  247.1 KB.

    The invoice even indicates that the intermediate lines they sent are for an 85 86 with 7.5 in Axle which leads me to think its the wrong line and not what I ordered. What I was expecting was an intermediate line for an 86 V8 with dual Exhaust. Classic Tube is insisting that the intermediate line for a 7.5 and 8.8 are exactly the same. Name:  Invoice.JPG
Views: 284
Size:  221.6 KB

    They asked for a picture of the routing of the original line which of course I don't have. Does any one have a picture that shows how the intermediate line for an 85 or 86 should run. I've seen serval pictures where folks have bent there own lines, but don’t think I've seen a good picture of how an original line is run.

    I did ask if there was another line that should run from the passenger side of the car to the center, but they guy had no answer. He said I must be installing it wrong.

    I guess its possible I'm doing something wrong but I was under the impression that the intermediate line for an 85 or 86 V8 would be different than an 84 V8 or 85/86 4 or 6 cylinder with single exhaust.
    Last edited by Crimson_Stang; 08-13-2018 at 11:25 PM.
    Have:
    84 GT 350 Anny 5.0
    05 F-150 Super Crew
    08 Saturn Outlook
    Had:
    00 Nissan Frontier
    97 Gand Prix GTP (Supercharged)
    87 Audi Coupe GT
    84 Mustang L 3.8

  10. #10
    FEP Super Member onetrackrider's Avatar
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    Apr 2009
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    Denver, Colorado
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    4,660

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    When I did true duels conversion on my 83 Carpi I used the brake lines from a 85 GT from the JY.
    Current rides:
    89 LX 5.0, 5 -spd..the Lemon
    86 RS Capri 5.0 Auto...
    86 LX Colorado SSP 5.0 5-spd (Sadly Sold)
    85.5 SVO, Finally Got Boost
    83 RS Capri 5.0, 5-spd (another sadly sold)

  11. #11

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    I haven’t had much luck finding Fox bodies in JY lately and I kind of wanted new stainless lines. Did the line run down the passenger side then over to the middle of the car a little before the passenger side wheel well?


    Sent from my iPhone using Tapatalk
    Have:
    84 GT 350 Anny 5.0
    05 F-150 Super Crew
    08 Saturn Outlook
    Had:
    00 Nissan Frontier
    97 Gand Prix GTP (Supercharged)
    87 Audi Coupe GT
    84 Mustang L 3.8

  12. #12

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    1985 was a strange year for the Mustang. You could get a Mustang GT with two 5.0l engines. One had CFI fuel injection, the other had a 4V carb. The CFI model had a single exhaust. The 4V model had dual exhausts. Both cars had a 7.5" differential.

    The CFI car had the rear brake line running down the inside of the right hand frame rail terminating with a brake hose that goes to a tee on the right hand axle tube, just like almost every other 7.5" axle installation. The high pressure fuel pump sits on the right side frame rail exactly where the right hand muffler would be. I have photos of this.

    I do not have any photos of the rear brake line routing for a 4V car. I'm 98% certain that it is not the same as a single exhaust 7.5" installation. The brake hose would practically touch the right side tail pipe. It must use essentially the same routing as all 8.8" installations.

    There is only one other Mustang with dual exhausts and a 7.5" axle. That is the 1985.5-86 SVO. This car has 8.8" style rear brake line routing, despite having the 7.5" axle. I believe that you could use a 1986 SVO rear brake line to fix your problem.

    I suspect that when Classic Tube made the rear brake line that you purchased, someone sent them a line from a 1985 CFI Mustang and the owner or Classic Tube did not know the difference between this and the 4V model routing.

    Classic Tube is absolutely wrong about a 7.5" and 8.8" rear brake line being the same. In the vast majority of applications there are different from each other.
    Jack Hidley
    Maximum Motorsports Tech Support

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