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Thread: 3 link banana strength question

  1. #1
    Brandon #9196 TexasAviator's Avatar
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    3 link banana strength question

    I have read that the banana can turn on the axle if not welded to the tube. Definately not hard to do and may come sooner than later but I was curious as to what you all thought.

    It has an arm that comes off the banana and goes under the 8.8 and gets bolted to the diff. Is this a new part that was added to later 3 link kits? Other threads made no mention of it. Now I am wondering if i need this 3 link brace kit from here. http://www.vintageperformancemotorcars.com/

    What do you all think?

  2. #2

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    RoadRacer's Avatar
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    I haven’t welded but have got the VPM brace - I figure it’s cheap insurance. Perfect fit and nicely made.
    James

    FFR33 #997 (Gen1 chassis, Gen2 body), license plate DRIVE IT says it all! build thread
    My build: 350SBC, TKO600, hardtop, no fenders/hood, 32 grill, 3 link, sway bars, 355/30r19
    Previous cars: GTD40, Cobra, tubeframe 55 Chevy, 66 Nova, 56 F100

  3. #3
    Boydster's Avatar
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    Moser unit is welded. I suggest welding because the first time you find out whether it needs to be welded or not, well, it's too late.

    Whats the "arm that comes off the banana and goes under the 8.8 and gets bolted to the diff."? Supplied by F5? Got a picture?
    ---Boyd---
    MkIV #9042 build thread
    www.boss427.us
    427W, TKO600, Moser 3.55 rear.
    Delivered Feb 2017, Graduated Nov 4, 2019

  4. #4
    PLATNUM Supporting Member
    wallace18's Avatar
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    It is a brace from Vintage Performance Motorcars. Only works with 8.8 that has 4 link ears next to diff. Will not work with Moser. I use it on all my 3-link builds. Cheap insurance, IMO.

    MK457.JPG

  5. #5
    Senior Member CraigS's Avatar
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    The arm under the diff is part of the FFR banana bracket. It has always been there. I like the VPM reinforcing struts myself. If you do decide to weld it, weld to both the diff center housing and the axle tube. Otherwise it can eventually rip apart on a diagonal tear of the split tubes that are bolted around the axle tube.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

  6. #6
    Seasoned Citizen NAZ's Avatar
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    It looks like you're planning to run a T5 M7003-Z trans with a 2.95:1 1st gear ratio. That trans is rated at 300 ft lbs of torque so you're not likely going to put much more than ~3,100 ft lbs of torque on the axle housing (assuming 300 ft lb at the flywheel and 3.55:1 rear gears). Welding the UCA bracket (banana bracket) to the axle tube with a couple of .12" x 2" fillet welds with ER70S-2 filler would seem to me to be sufficient. Making the beads linear with the axle tube rather than radially would lessen the chance of warping the rather thin axle tubes. If you tie the welding into the cast steel center section (not my recommendation on this application) I would advise you to use the TIG process with 99% nickel filler and small beads immediately stress relieved while cooling to prevent cracking the casting.

  7. #7
    Brandon #9196 TexasAviator's Avatar
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    Quote Originally Posted by RoadRacer View Post
    I haven’t welded but have got the VPM brace - I figure it’s cheap insurance. Perfect fit and nicely made.
    That is my thoughts as well.

    Quote Originally Posted by Boydster View Post
    Moser unit is welded. I suggest welding because the first time you find out whether it needs to be welded or not, well, it's too late.

    Whats the "arm that comes off the banana and goes under the 8.8 and gets bolted to the diff."? Supplied by F5? Got a picture?
    The only pictures I have are in my build thread but they are not really focused on that and I am out of town at the moment.

    37742872941_5804c16036_h.jpg

    Quote Originally Posted by wallace18 View Post
    It is a brace from Vintage Performance Motorcars. Only works with 8.8 that has 4 link ears next to diff. Will not work with Moser. I use it on all my 3-link builds. Cheap insurance, IMO.

    MK457.JPG
    I am running a mustang 8.8 with the ears. It will work, but I think I would rather weld it.

    Quote Originally Posted by CraigS View Post
    The arm under the diff is part of the FFR banana bracket. It has always been there. I like the VPM reinforcing struts myself. If you do decide to weld it, weld to both the diff center housing and the axle tube. Otherwise it can eventually rip apart on a diagonal tear of the split tubes that are bolted around the axle tube.
    Thanks for that, I believe that to be the right way as well.

    Quote Originally Posted by NAZ View Post
    It looks like you're planning to run a T5 M7003-Z trans with a 2.95:1 1st gear ratio. That trans is rated at 300 ft lbs of torque so you're not likely going to put much more than ~3,100 ft lbs of torque on the axle housing (assuming 300 ft lb at the flywheel and 3.55:1 rear gears). Welding the UCA bracket (banana bracket) to the axle tube with a couple of .12" x 2" fillet welds with ER70S-2 filler would seem to me to be sufficient. Making the beads linear with the axle tube rather than radially would lessen the chance of warping the rather thin axle tubes. If you tie the welding into the cast steel center section (not my recommendation on this application) I would advise you to use the TIG process with 99% nickel filler and small beads immediately stress relieved while cooling to prevent cracking the casting.
    NAZ, yes I am running the T5 M7003Z gear set. In my 3.35 geared foxbody I would have to shift almost immediately after launch. It would chew through blocker rings (syncro) and would not put me in the ideal rpm. With this gear set it wont torque the car as hard, allow me to stay in first gear longer off the line and keep me from going immediately to second. This alone can save transitions on the blocker rings from 1-2 helping longevity. As you said it will be a little gentler on the axle as well. Its a street car but would definitely like to heed your advice to allow for some occasional track days with out worrying about this part.
    Last edited by TexasAviator; 10-27-2017 at 09:39 AM.

  8. #8
    Senior Member CraigS's Avatar
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    Quote Originally Posted by NAZ View Post
    It looks like you're planning to run a T5 M7003-Z trans with a 2.95:1 1st gear ratio. That trans is rated at 300 ft lbs of torque so you're not likely going to put much more than ~3,100 ft lbs of torque on the axle housing (assuming 300 ft lb at the flywheel and 3.55:1 rear gears). Welding the UCA bracket (banana bracket) to the axle tube with a couple of .12" x 2" fillet welds with ER70S-2 filler would seem to me to be sufficient. Making the beads linear with the axle tube rather than radially would lessen the chance of warping the rather thin axle tubes. If you tie the welding into the cast steel center section (not my recommendation on this application) I would advise you to use the TIG process with 99% nickel filler and small beads immediately stress relieved while cooling to prevent cracking the casting.
    This is another reason I don't really like the welding. Different techniques needed, that I for one don't have, (stress relieve while cooling?) and the possibility of warping the axle tube and wrecking the rear wheel alignment.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

  9. #9
    Senior Member cgundermann's Avatar
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    I didn't weld mine because I had my axle powder coated silver vien, but was worried about the strength where it attaches to the axle tab. Didn't know VPM made this support brace, - just ordered it!

    Thanks,

    Chris

  10. #10
    Senior Member BEAR-AvHistory's Avatar
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    Are the "ears" the two round loops with the rubber donuts in them?
    Kevin
    MKIV #8234
    Coyote '14/TKO-600/3-Link 3:55 Rear
    I love the smell of 100 octane in the morning.
    NITTO NT01 275X40X17ZR - 315X35ZRX17
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  11. #11
    Senior Member cgundermann's Avatar
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    Quote Originally Posted by BEAR-AvHistory View Post
    Are the "ears" the two round loops with the rubber donuts in them?
    Yes, that is correct.

    Chris

  12. #12
    Senior Member cobrajj's Avatar
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    I didn't want to weld mine, and installed the support brace from VPM.142-4232_IMG.JPG
    Mk3.1 Complete kit #6846 Delv. 12/20/08-- Finished 2/11/11, 89 302 EFI,T-5, 3-Link, 17" Halibrands, Nitto 555 245-315 tires, widened drivers footbox w/ dead pedal, extended passengers footbox,Sapphire Blue Met & Wimbledon White stripes,radiator stone guard shield, Build blog http://jimsffrcobrabuild.blogspot.com/

  13. #13
    Senior Member BEAR-AvHistory's Avatar
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    Quote Originally Posted by cgundermann View Post
    Yes, that is correct.

    Chris
    Thanks.
    Kevin
    MKIV #8234
    Coyote '14/TKO-600/3-Link 3:55 Rear
    I love the smell of 100 octane in the morning.
    NITTO NT01 275X40X17ZR - 315X35ZRX17
    Delivered 2/7/14 - Plate "COYOTE NC1965" 3/25/15

  14. #14
    Brandon #9196 TexasAviator's Avatar
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    Quote Originally Posted by cgundermann View Post
    I didn't weld mine because I had my axle powder coated silver vien, but was worried about the strength where it attaches to the axle tab. Didn't know VPM made this support brace, - just ordered it!

    Thanks,

    Chris


    Your welcome man. I found out about from just scanning builds on this site.

  15. #15
    Senior Member BEAR-AvHistory's Avatar
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    Brace just came in. Next down day (bad weather) will do the install. Is there any load on the banana if I support the car with jack stands under the axle?
    Kevin
    MKIV #8234
    Coyote '14/TKO-600/3-Link 3:55 Rear
    I love the smell of 100 octane in the morning.
    NITTO NT01 275X40X17ZR - 315X35ZRX17
    Delivered 2/7/14 - Plate "COYOTE NC1965" 3/25/15

  16. #16
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    Quote Originally Posted by BEAR-AvHistory View Post
    Brace just came in. Next down day (bad weather) will do the install. Is there any load on the banana if I support the car with jack stands under the axle?
    Yes. Support the car with stands on the frame and slightly lift the axle with a jack. Still be careful as the axle might rotate.

  17. #17
    Senior Member BEAR-AvHistory's Avatar
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    Quote Originally Posted by totem View Post
    Yes. Support the car with stands on the frame and slightly lift the axle with a jack. Still be careful as the axle might rotate.
    Thanks, will do.
    Kevin
    MKIV #8234
    Coyote '14/TKO-600/3-Link 3:55 Rear
    I love the smell of 100 octane in the morning.
    NITTO NT01 275X40X17ZR - 315X35ZRX17
    Delivered 2/7/14 - Plate "COYOTE NC1965" 3/25/15

  18. #18
    Senior Member cgundermann's Avatar
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    Quote Originally Posted by totem View Post
    Yes. Support the car with stands on the frame and slightly lift the axle with a jack. Still be careful as the axle might rotate.
    Just installed mine and that's what I did. Even then, once the third link bar is detached from the banana bracket - it will move. When you re-connect with the new brace, you can roll/push/jack it back in to get the third link bar into place. Very nice piece in terms of price, quality & engineering. Money well spent!

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