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Thread: Transmission and differential alignment

  1. #1
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    Question Transmission and differential alignment

    Hi all,
    While I was crawling around under the chassis checking bolts and torques prior to first go-cart, I noticed that the driveshaft is running “uphill” towards the IRS center section. In other words the output of the tranny (TKO600) is lower than the input of the diff. Looks like about a half inch low. With a driveshaft this short (about 2” plus 2 u-joints), the angle is rather steep. See photo:

    thumb_DSCF0143_1024.jpg
    thumb_DSCF0143_1024.jpg
    Is this normal? Should I try to raise the rear end of the transmission? I am looking forward to any advice you can give me.

    Thanks,
    Jeff
    Mk4 Complete kit with IRS, IRS brakes, Power Steering, 302 mounts, 302 headers, TKO, 2 Rollbars, Leather seats,
    vintage gauges, polished stainless sidepipes, front and rear sway bars, all cutouts.
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    Jeff, there are many threads on this and I believe Edwardb has a very good write up in his latest Roadster build log. Not trying to be a jerk, but just to let you know there is a lot of information on the forum. I'm working on angles for an 8.8 as I type this.

    Scott
    Built FFR9457. 351 Windsor, TKO600, 3.73. Fitech EFI. Russ Thompson throttle pedal, turn signal, and trunk pan. Carbon Fiber dash with Speedhut Revolution gauges. Paint by Jeff Kleiner.

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    Cool I'll search the forum, thanks

    Quote Originally Posted by Sdonnel View Post
    Jeff, there are many threads on this and I believe Edwardb has a very good write up in his latest Roadster build log. Not trying to be a jerk, but just to let you know there is a lot of information on the forum. I'm working on angles for an 8.8 as I type this.

    Scott
    Hey, thanks. I'll search the forum, but usually I have trouble finding stuff. I'm still new at this. I'll look at edwardb's roadster build.
    Mk4 Complete kit with IRS, IRS brakes, Power Steering, 302 mounts, 302 headers, TKO, 2 Rollbars, Leather seats,
    vintage gauges, polished stainless sidepipes, front and rear sway bars, all cutouts.
    Blueprint Engines 347 stroker; Tremec TKO 600; 3.55 IRS, 17" Bullitt wheels: 9" front 10.5" rear.
    Delivered Nov. 6, 2018. First start Aug. 11, 2019. First Go-Cart Feb. 21, 2020.

  4. #4
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    Quote Originally Posted by Sdonnel View Post
    Jeff, there are many threads on this and I believe Edwardb has a very good write up in his latest Roadster build log. Not trying to be a jerk, but just to let you know there is a lot of information on the forum. I'm working on angles for an 8.8 as I type this.

    Scott
    Agreed,

    The search function lacks bit of user friendliness, but the info is there. It can be difficult to locate, but its there...now if I could only find the link! LOL. EdwardB's write up is great and should be included in the manual. But there are some others also. Here's an article that's helpful and there are some You-Tube videos that are also helpful. https://therangerstation.com/tech_li...onangles.shtml
    FFR MKIV ordered 12 July 2019. IRS, Wilwood Brakes, 18" Wheels w/MT tires, power steering, EFI, Heat. 347 Dart w/TKO-600 by Mike Forte, Holley FI, MSD coil and CD box. All new, no donor build.

  5. #5
    Senior Member Avalanche325's Avatar
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    Search for "pinion angle".

    You do not want them in a straight line. Basically, looking from the side, the rear of the transmission points down and the front of the diff points up.

  6. #6
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    Really?
    I will try to find pinion angle.
    Thanks,
    Jeff
    Mk4 Complete kit with IRS, IRS brakes, Power Steering, 302 mounts, 302 headers, TKO, 2 Rollbars, Leather seats,
    vintage gauges, polished stainless sidepipes, front and rear sway bars, all cutouts.
    Blueprint Engines 347 stroker; Tremec TKO 600; 3.55 IRS, 17" Bullitt wheels: 9" front 10.5" rear.
    Delivered Nov. 6, 2018. First start Aug. 11, 2019. First Go-Cart Feb. 21, 2020.

  7. #7

    Steve >> aka: GoDadGo
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    We've shared this video a bunch so I'm sure it will help.

    https://youtu.be/Idk3BVDVHq4

  8. Thanks Jeff's First FFR, CNIdog thanked for this post
  9. #8
    Senior Member edwardb's Avatar
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    Doesn't look that bad. Keep in mind with IRS that angle doesn't change. So it won't be any more than that. And as others have said, you don't want them exactly in line, if that's what you're looking for. But proof is in the pinion angle measurement. Do you have a spacer under the transmission rear mount? Pretty typical for a TKO to require a 3/4-inch or sometimes more spacer.
    Build 1: Mk3 Roadster #5125. Sold 11/08/2014. Build 2: Mk4 Roadster #7750. Sold 04/10/2017. Build Thread
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  10. #9
    Senior Member Gromit's Avatar
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    if you use Google, in the search put in

    site:thefactoryfiveforum.com pinion angle

    you will get about 400 relevant hits and pictures.
    the site: keyword is secret that should be told to every google user.

    Gromit AKA Chris O
    Last edited by Gromit; 09-10-2019 at 03:44 PM. Reason: typo fix

  11. #10

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    While you're searching for "pinion Angle", also search for "U-joint Operating Angle".

    Read and understand articles like this one: https://therangerstation.com/tech_li...onangles.shtml

    Remember to measure your angles in two planes, horizontal and vertical. Horizontal is much more difficult to measure.
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    Cool

    Quote Originally Posted by GoDadGo View Post
    We've shared this video a bunch so I'm sure it will help.

    https://youtu.be/Idk3BVDVHq4
    Great video? thanks
    Mk4 Complete kit with IRS, IRS brakes, Power Steering, 302 mounts, 302 headers, TKO, 2 Rollbars, Leather seats,
    vintage gauges, polished stainless sidepipes, front and rear sway bars, all cutouts.
    Blueprint Engines 347 stroker; Tremec TKO 600; 3.55 IRS, 17" Bullitt wheels: 9" front 10.5" rear.
    Delivered Nov. 6, 2018. First start Aug. 11, 2019. First Go-Cart Feb. 21, 2020.

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    Quote Originally Posted by edwardb View Post
    Doesn't look that bad. Keep in mind with IRS that angle doesn't change. So it won't be any more than that. And as others have said, you don't want them exactly in line, if that's what you're looking for. But proof is in the pinion angle measurement. Do you have a spacer under the transmission rear mount? Pretty typical for a TKO to require a 3/4-inch or sometimes more spacer.
    Thank you,
    I have no spacer other than the urethane mount provided. Since Factory Five "did the engineering" it should be correct. Looks like about 3 degrees each at trans and diff. a little much, but if I raise the trans then the angles will no longer be equal. I hope to measure the angles more accurately, soon as I lift it up.
    Thanks again, you always have the answer,
    Jeff
    Mk4 Complete kit with IRS, IRS brakes, Power Steering, 302 mounts, 302 headers, TKO, 2 Rollbars, Leather seats,
    vintage gauges, polished stainless sidepipes, front and rear sway bars, all cutouts.
    Blueprint Engines 347 stroker; Tremec TKO 600; 3.55 IRS, 17" Bullitt wheels: 9" front 10.5" rear.
    Delivered Nov. 6, 2018. First start Aug. 11, 2019. First Go-Cart Feb. 21, 2020.

  14. #13
    Senior Member edwardb's Avatar
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    Quote Originally Posted by Jeff's First FFR View Post
    ...if I raise the trans then the angles will no longer be equal.
    I know that's referenced in the linked video. But the angles shown are radically extreme. Far beyond the 1-2 degrees you should see for an acceptable pinion angle. Typically the diff is pointed up slightly to the front, and the engine/trans down to the back. In my experience, properly set up you won't have any issues even if they're not exactly the same.

    Quote Originally Posted by Jeff's First FFR View Post
    I have no spacer other than the urethane mount provided. Since Factory Five "did the engineering" it should be correct...
    With all due respect to my friends at Factory Five, you assume a lot there. Every build I've done and also helped with has required a transmission spacer to eliminate interference between the tailshaft of the transmission and the 4-inch tube cross member. Plus to get an acceptable pinion angle. Especially with a TKO. I've always been a little puzzled why this isn't at least mentioned in the manual. I'm not the only one. Regularly cited in multiple build threads.
    Last edited by edwardb; 09-10-2019 at 10:47 PM.
    Build 1: Mk3 Roadster #5125. Sold 11/08/2014. Build 2: Mk4 Roadster #7750. Sold 04/10/2017. Build Thread
    Build 3: Mk4 Roadster 20th Anniversary #8674. Sold 09/07/2020. Build Thread and Video. Build 4: Gen 3 Type 65 Coupe #59. Gen 3 Coyote. Legal 03/04/2020. Build Thread and Video
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  15. #14
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    You must also realize that there are many different engine mounts that mount the engine higher or lower depending on the type of Ford part or aftermarket mount you use. There are also a number of different transmission choices that again may differ from one another. Thus FFR has made that mount lower so that all those factors can be addressed adding different amounts of shimming at the rear transmission mount until the right pinion angle is achieved.

    Yes, FFR should explain that in their manual and in not doing so makes you wonder if it was intentional or not.

    George

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    Cool

    Quote Originally Posted by edwardb View Post
    I know that's referenced in the linked video. But the angles shown are radically extreme. Far beyond the 1-2 degrees you should see for an acceptable pinion angle. Typically the diff is pointed up slightly to the front, and the engine/trans down to the back. In my experience, properly set up you won't have any issues even if they're not exactly the same.



    With all due respect to my friends at Factory Five, you assume a lot there. Every build I've done and also helped with has required a transmission spacer to eliminate interference between the tailshaft of the transmission and the 4-inch tube cross member. Plus to get an acceptable pinion angle. Especially with a TKO. I've always been a little puzzled why this isn't at least mentioned in the manual. I'm not the only one. Regularly cited in multiple build threads.
    Yes, that is a lot to assume. with all the different engine /transmission variations available it is sure to be a compromise. I will re-visit putting a spacer under the rear of the transmission. I have a digital angle finder, so after I finish my wheel alignment I will raise the chassis (angle won't change because of IRS) and make a measurement then visit my friendly ACE hardware store. With such a short driveshaft it is best to be more precise.

    But, yes at least FFR could have mentioned it. They just left more for us to talk about. I really like the forum.

    BTW
    https://therangerstation.com/tech_li...onangles.shtml is a very good reference.
    Thanks to Bob Cowan


    Jeff
    Last edited by Jeff's First FFR; 09-11-2019 at 05:50 AM.
    Mk4 Complete kit with IRS, IRS brakes, Power Steering, 302 mounts, 302 headers, TKO, 2 Rollbars, Leather seats,
    vintage gauges, polished stainless sidepipes, front and rear sway bars, all cutouts.
    Blueprint Engines 347 stroker; Tremec TKO 600; 3.55 IRS, 17" Bullitt wheels: 9" front 10.5" rear.
    Delivered Nov. 6, 2018. First start Aug. 11, 2019. First Go-Cart Feb. 21, 2020.

  17. #16
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    Cool

    Quote Originally Posted by edwardb View Post
    Doesn't look that bad. Keep in mind with IRS that angle doesn't change. So it won't be any more than that. And as others have said, you don't want them exactly in line, if that's what you're looking for. But proof is in the pinion angle measurement. Do you have a spacer under the transmission rear mount? Pretty typical for a TKO to require a 3/4-inch or sometimes more spacer.
    Well, Paul, you are right. The trans needs a spacer. The trans is almost resting on the 4” crossmember. The IRS pinion shaft is parallel to the frame 4” long tubes. The trans points down 5 degrees. The two shaft angles are definitely different. So from trigonometry and 5.5 inches between u-joint pivots tan5*5.5=0.48”.
    I thought it looked like it needs more like 1”. Well off to ACE.

    Jeff
    Mk4 Complete kit with IRS, IRS brakes, Power Steering, 302 mounts, 302 headers, TKO, 2 Rollbars, Leather seats,
    vintage gauges, polished stainless sidepipes, front and rear sway bars, all cutouts.
    Blueprint Engines 347 stroker; Tremec TKO 600; 3.55 IRS, 17" Bullitt wheels: 9" front 10.5" rear.
    Delivered Nov. 6, 2018. First start Aug. 11, 2019. First Go-Cart Feb. 21, 2020.

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