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Thread: Differential travel

  1. #1

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    Differential travel

    How much vertical travel should I expect for a solid axel (Moser 8.8)?

    I am using the complete kit stock Koni shocks with 350# springs.

    I was so happy my pinion angle was within limits right from the start with no adjustments that I neglected to look at my battery box and differential housing clearance. It was my muffler guy who asked me what I was going to do about the clearance! As you can see sitting at ride height, the two just make contact with each other with no room for upward movement. Well my best (cheapest) solution considering I already bought the battery and the FF Metal battery box is to cut and shorten the bottom of the battery box. I was thinking 1.5 inches should clear it? Would 1.5 inches be enough? I could live with the battery taking up space sitting above the floor of the trunk. And with 1.5 inches higher on top by the posts, I would not need to make adjustments for the battery cables. If I need to go over 1.5 inches by the battery posts I might need to reroute the battery cables and/or re-run longer battery cables $$$. Of course I would make a shroud to protect the battery posts from above. My last option is to look at the original cover to see if it would clear. However, that would involve draining the oil, taking the cover off, etc. What do you experts think?

    build thread: http://thefactoryfiveforum.com/showt...-USRRC-vspeeds

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  2. #2
    Not a waxer Jeff Kleiner's Avatar
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    I'd hit the easy button and change the cover.

    Jeff

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  4. #3

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    2-1/2 - 3". You can measure the distance the shocks have to travel to the bump stop plus maybe 1/2 the height of the bump stop as a worst case fully bottomed position.

    If you don't want to give up on the support cover then plan B is:

    https://www.breezeautomotive.com/sho...-1-4-roadster/
    Last edited by Mark Reynolds; 12-13-2018 at 01:13 PM. Reason: spelling
    www.breezeautomotive.com 2005 FFR Mk3 Roadster, 302/340hp, MassFlo EFI, Breeze Pulleys, T5, Aluminum Flywheel, 3-link rear with Torsen Diff and 3.27:1 gears, Power Steering, Breeze Front Sway Bar, SN-95 Spindles with outboard SAI Mod, Breeze Battery Mount, QA1 Externally Adjustable Shocks, Quick Release Steering Wheel, Vintage Race seats, GM Arctic White, Sky Blue Scoop, Hidden Hinges, Billet Aluminum Side-view Mirrors, 2,183lbs wet. 1967 Mustang Fastback, Dark Moss Green, black interior, '67 14" styled steel wheels, 2000 Explorer 302 w 5.0 Cam, Quickfuel 450 CFM, 289 Hi-Po Dual exhaust, C4, lowering springs w Shelby drop.

  5. #4
    Member aspbite's Avatar
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    Quote Originally Posted by jeff kleiner View Post
    i'd hit the easy button and change the cover.

    Jeff
    Mark IV, Boss 351c, Toploader, Levy 5 link

  6. #5
    Senior Member CraigS's Avatar
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    I know those nice covers have a use but probably not as important in an FFR than in a Mustang. Reason I say that is we are way traction limited unless you will be running drag radials. I bet the OE steel cover will clear. BTW the jam nut on your third link is not tight.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

  7. #6
    Senior Member kobra01's Avatar
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    Same problem with my car. Put stock type diff cover on it, unbolted one end of the shocks and ran suspension through full travel and it's all good now.
    MK4 Roadster # 8548, Ford Performance X427, TKO 600, 8.8 3 Link, Paint by Jeff Miller, Suspension setup by Frank Maslowski I.E.427

  8. #7
    Senior Member Dave Howard's Avatar
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    I have the exact same set up and had the same issue. My solution was to remove the rivets securing the front of the battery box. I cut, a piece of aluminum approximately 1.5" wide by the length of the the battery box. This was riveted to the front of the battery box, making the front wall taller than the back wall of the box. The extended front wall was re-secured in the original holes. This pushed the front of the box down and tilted it back enough to clear the diff cover under full range of diff movement.
    MkIV #7854, Kit picked up September 2012, Coyote/BOSS 302 intake tuned at 488HP, TKO600, Center Force, Moser 8.8, driveshaft safety hoop, Stainless Header 4x1x4 headers, Gas-N-sidepipes, rad shroud, Wilwoods, NO PS/PB, heater/defroster, heated seats, wipers, Herb door panels, Dynamat Extreme sound/heat dampening, premium Rodtop top, Fast Freddie lexan wind screen, Nitto 555R, drop trunk battery, drop trunk storage,

  9. #8
    Senior Member rich grsc's Avatar
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    Those fancy expensive covers aren't what they're claim, watch some of this series.
    https://www.youtube.com/watch?v=9-yG3D3JBRs

  10. #9
    Senior Member Avalanche325's Avatar
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    Geeze Rich, you must be a real car nerd. You watch the same videos that I do!

    I was going to refer to the same thing. The bearing preload "sounds" nice, but really isn't an issue on these cars. Not sure about the cover you have, but he shows some real oil flow issues with some.

    500hp, Nitto NT05s, 4 years of autocross with hard launches, 20K miles and no differential issues. My transmission is on my workbench right now, but that's a different story.

  11. #10
    Senior Member Fixit's Avatar
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    Change the cover. (BTW I love the "hit the easy button").

    The video by Gale is an eye-opener, and really reinforces the old saying "Chrome Don't Get You Home".
    John D. - Minneapolis 'Burbs

    1965 El Camino - LT-1, 4L60e, 4wh discs, SC&C susp.
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    2018 Mk4 Roadster w/ Coyote - #9365 - Build Thread Delivery 7/3/18, 1st Start 1/4/19, 1st Road Mile 5/5/19, Legal 6/18/19, In Paint 2/25/21, Done (?) 4/2021

  12. #11
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    That looks like a Moser cover as I have one. They have a curved back for ring gear oil flow and They have a purpose if you make enough torque to need it. Plus they have a drain port for fluid changes. They are nice pieces with solid engineering in them unlike some parts that are poorly engineered and or made and are all about looks. Personally I would move or angle the battery box and call it a day as it’s a easy enough change.
    Last edited by GFX2043mtu; 12-11-2018 at 08:08 PM.
    Mk4, Moser M88 rear end, Eaton truetrak, Craft Racing 461 Windsor, MMR pro trans, Glenn’s 1,000 hp cobra fuel system and lots of other parts.

  13. #12
    Senior Member rich grsc's Avatar
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    Quote Originally Posted by Avalanche325 View Post
    Geeze Rich, you must be a real car nerd. You watch the same videos that I do!

    I was going to refer to the same thing. The bearing preload "sounds" nice, but really isn't an issue on these cars. Not sure about the cover you have, but he shows some real oil flow issues with some.

    500hp, Nitto NT05s, 4 years of autocross with hard launches, 20K miles and no differential issues. My transmission is on my workbench right now, but that's a different story.
    That may be the nicest thing anyone on this forum has called me. Thanks

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  15. #13

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    Quote Originally Posted by Jeff Kleiner View Post
    I'd hit the easy button and change the cover.

    Jeff
    I don't think I can use that easy button. It seems the stock cover would hit also. I think the issue is with the pre-welded banana bar onto the axle. It doesn't leave me with much angle to play with. I needed to set the banana bar all the way back along with 3/4 spacers at the transmission to get the pinion angle right. With that rear most setting is why the battery box is hitting.
    build thread: http://thefactoryfiveforum.com/showt...-USRRC-vspeeds

    Build School: July 14-16, 2017
    Kit purchased: July 25, 2017
    Kit delivered: September 13, 2017
    First Start: December 22, 2018
    Body painted and kit completed and drivable: July 2019 (but still not done)
    CA SB100 Registration: January 2020

    Mk4 - 289 USRRC Roadster kit, Roush 427SR with Schneider Racing custom camshaft, Fitech EFI, TKO600 (.64-5th gear), 15" wheels, stock brake calipers, under car exhaust with Spintech 7000 muffler, no roll bar, Russ Thompson turn signal, removable steering wheel, and many other small upgrades and modifications

  16. #14

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    Quote Originally Posted by Dave Howard View Post
    I have the exact same set up and had the same issue. My solution was to remove the rivets securing the front of the battery box. I cut, a piece of aluminum approximately 1.5" wide by the length of the the battery box. This was riveted to the front of the battery box, making the front wall taller than the back wall of the box. The extended front wall was re-secured in the original holes. This pushed the front of the box down and tilted it back enough to clear the diff cover under full range of diff movement.
    Thanks. Thats a clever solution to tilt the box.
    build thread: http://thefactoryfiveforum.com/showt...-USRRC-vspeeds

    Build School: July 14-16, 2017
    Kit purchased: July 25, 2017
    Kit delivered: September 13, 2017
    First Start: December 22, 2018
    Body painted and kit completed and drivable: July 2019 (but still not done)
    CA SB100 Registration: January 2020

    Mk4 - 289 USRRC Roadster kit, Roush 427SR with Schneider Racing custom camshaft, Fitech EFI, TKO600 (.64-5th gear), 15" wheels, stock brake calipers, under car exhaust with Spintech 7000 muffler, no roll bar, Russ Thompson turn signal, removable steering wheel, and many other small upgrades and modifications

  17. #15

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    Quote Originally Posted by rich grsc View Post
    Those fancy expensive covers aren't what they're claim, watch some of this series.
    https://www.youtube.com/watch?v=9-yG3D3JBRs

    Thanks Rich. Thats an interesting video. I subscribed to their channel
    build thread: http://thefactoryfiveforum.com/showt...-USRRC-vspeeds

    Build School: July 14-16, 2017
    Kit purchased: July 25, 2017
    Kit delivered: September 13, 2017
    First Start: December 22, 2018
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    Mk4 - 289 USRRC Roadster kit, Roush 427SR with Schneider Racing custom camshaft, Fitech EFI, TKO600 (.64-5th gear), 15" wheels, stock brake calipers, under car exhaust with Spintech 7000 muffler, no roll bar, Russ Thompson turn signal, removable steering wheel, and many other small upgrades and modifications

  18. #16

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    Quote Originally Posted by GFX2043mtu View Post
    That looks like a Moser cover as I have one. They have a curved back for ring gear oil flow and They have a purpose if you make enough torque to need it. Plus they have a drain port for fluid changes. They are nice pieces with solid engineering in them unlike some parts that are poorly engineered and or made and are all about looks. Personally I would move or angle the battery box and call it a day as it’s a easy enough change.
    That is why I purchased it and will leave it on. I like the look and features to has. However, that video was interesting and makes me wonder how much of an improvement it is.
    build thread: http://thefactoryfiveforum.com/showt...-USRRC-vspeeds

    Build School: July 14-16, 2017
    Kit purchased: July 25, 2017
    Kit delivered: September 13, 2017
    First Start: December 22, 2018
    Body painted and kit completed and drivable: July 2019 (but still not done)
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    Mk4 - 289 USRRC Roadster kit, Roush 427SR with Schneider Racing custom camshaft, Fitech EFI, TKO600 (.64-5th gear), 15" wheels, stock brake calipers, under car exhaust with Spintech 7000 muffler, no roll bar, Russ Thompson turn signal, removable steering wheel, and many other small upgrades and modifications

  19. #17

    Steve >> aka: GoDadGo
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    Quote Originally Posted by Jeff Kleiner View Post
    I'd hit the easy button and change the cover.

    Jeff
    You could hit the "Hard Button" and shorten the wheel base so that it clears the battery box while better centering the wheels within the wheel arches....That solution may work; however, it will require new shorter lower control arms, possibly a new shorter upper link and of course a new shortened drive shaft....After that you get to worry about your tire clearance on the back side of the cockpit aluminum plus you even get to worry about U-Joint bind too.

    Personally I'd hit the "Easy Button" but then again it's so much fun making Stone Soup!

    The Stone Soup MK-4:
    https://youtu.be/_wnHDNgnNqs
    https://youtu.be/IGYtX-3p7xk
    https://youtu.be/NhRHwAbtrt0

    All Kidding Aside, Good Luck From The Dark-Dart Side

    Steve...>>>------------------------->...aka: Stone Soup Steve
    Last edited by GoDadGo; 12-12-2018 at 09:00 AM.

  20. #18
    Bill_VA's Avatar
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    Is the battery box in the center of the trunk or over to the left? The instructions say to mount it to the left for solid axles and in the center for IRS.
    Non-donor - Engine Factory 351w/400hp - TKO500 - 3-Link - Cobra brakes - FFmetal - Wilwood pedals - FR500 wheels - NCPainter

    Owner of FFmetal.com

  21. #19
    Administrator David Hodgkins's Avatar
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    I hit the easy button on my brother's 15th anniversary build:












    FFR 5369 Pin Drive, IRS, Trigos, Torsen, Wilwoods, FMS BOSS 302 "B" cam , Mass-flo. CA SB100 (SPCN) Registered
    Delivered 4/23/06. "Finished" 4/2012 (still not done!)


  22. #20
    Mark Eaton's Avatar
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    Quote Originally Posted by rich grsc View Post
    Those fancy expensive covers aren't what they're claim, watch some of this series.
    https://www.youtube.com/watch?v=9-yG3D3JBRs
    I watched three of these videos and am intrigued by his scientific approach. I couldn't fine a video where he actually measured the "heat" or change in viscosity secondary to aeration of the lube with the different covers which is what he says robs you of HP. Did he do that video?
    MK4 #9130 , complete kit, arrived 8/10/2017, Street Legal 2/14/2020.
    DART SHP 347, EFI, TKO600, IRS
    http://thefactoryfiveforum.com/showt...n-Build-Thread

  23. #21

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    Thanks guys. I decided the easiest for me was to raise the battery box. I wish I read the reply about tilting the box before I raised mine. I raised/shortened it by cutting the bottom section by 2.5". and left the top the same height. If I raised the entire box I wouldn't be able to remove the battery in the trunk. So now the battery sits above the trunk about 2". When I go kart Ill monitor the vertical travel of the pumpkin (using a camera) and if needed I could raise the battery box more fairly easily.

    build thread: http://thefactoryfiveforum.com/showt...-USRRC-vspeeds

    Build School: July 14-16, 2017
    Kit purchased: July 25, 2017
    Kit delivered: September 13, 2017
    First Start: December 22, 2018
    Body painted and kit completed and drivable: July 2019 (but still not done)
    CA SB100 Registration: January 2020

    Mk4 - 289 USRRC Roadster kit, Roush 427SR with Schneider Racing custom camshaft, Fitech EFI, TKO600 (.64-5th gear), 15" wheels, stock brake calipers, under car exhaust with Spintech 7000 muffler, no roll bar, Russ Thompson turn signal, removable steering wheel, and many other small upgrades and modifications

  24. #22
    Bill_VA's Avatar
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    Can you take a picture of what it looks like from inside the trunk?
    Non-donor - Engine Factory 351w/400hp - TKO500 - 3-Link - Cobra brakes - FFmetal - Wilwood pedals - FR500 wheels - NCPainter

    Owner of FFmetal.com

  25. #23

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    Quote Originally Posted by Bill_VA View Post
    Is the battery box in the center of the trunk or over to the left? The instructions say to mount it to the left for solid axles and in the center for IRS.
    Bill_VA

    Yes the box is positioned to the farthest left. Here pics from the trunk. When I get the final clearance I need, I'll build a removable shroud around the battery. I could also find a lower height battery



    build thread: http://thefactoryfiveforum.com/showt...-USRRC-vspeeds

    Build School: July 14-16, 2017
    Kit purchased: July 25, 2017
    Kit delivered: September 13, 2017
    First Start: December 22, 2018
    Body painted and kit completed and drivable: July 2019 (but still not done)
    CA SB100 Registration: January 2020

    Mk4 - 289 USRRC Roadster kit, Roush 427SR with Schneider Racing custom camshaft, Fitech EFI, TKO600 (.64-5th gear), 15" wheels, stock brake calipers, under car exhaust with Spintech 7000 muffler, no roll bar, Russ Thompson turn signal, removable steering wheel, and many other small upgrades and modifications

  26. #24
    Bill_VA's Avatar
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    That's a "creative" solution. Battery removal will be a concern for sure. FYI, I have one of those aluminum diff covers and have no clearance issues - it's tight, but no contact.
    Non-donor - Engine Factory 351w/400hp - TKO500 - 3-Link - Cobra brakes - FFmetal - Wilwood pedals - FR500 wheels - NCPainter

    Owner of FFmetal.com

  27. #25

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    I raised the battery box raised 2.5". While go karting, I've been monitoring the travel of the differential. Here is an excerpt of some footage:


    https://youtu.be/HTmZVjMgJ5A
    build thread: http://thefactoryfiveforum.com/showt...-USRRC-vspeeds

    Build School: July 14-16, 2017
    Kit purchased: July 25, 2017
    Kit delivered: September 13, 2017
    First Start: December 22, 2018
    Body painted and kit completed and drivable: July 2019 (but still not done)
    CA SB100 Registration: January 2020

    Mk4 - 289 USRRC Roadster kit, Roush 427SR with Schneider Racing custom camshaft, Fitech EFI, TKO600 (.64-5th gear), 15" wheels, stock brake calipers, under car exhaust with Spintech 7000 muffler, no roll bar, Russ Thompson turn signal, removable steering wheel, and many other small upgrades and modifications

  28. #26

    Steve >> aka: GoDadGo
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  29. #27
    Senior Member cgundermann's Avatar
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    I was a little surprised when I heard just 2 1/2 to 3”. Looks minimal or even less than that in the video...but, it’s a race car.

    I’d be curious how much the IRS has. After 5 neck surgeries, going to shift probably to IRS if I make the Coupe.

    Chris
    Generation 3 Type 65 Daytona Coupe Complete Kit #151885 received May 6, 2022. Gen 3 Coyote, IRS, Tremec TKX, American Powertrain hydraulic throwout bearing & Wilwood brakes.

    MK4 Basic Kit #7404, 347 EFI - Pro M Racing ECM, 30# injectors, 70 mm throttle body, 80 mm MAF, Edelbrock Performer aluminum heads & RPM II intake, all new G-Force T5, 3:55 gears, Pro 5.0 shifter, 3-link, carbon fiber dash/custom Speedhut gauges and paint by Da Bat.

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