# RWD Transmission Linkage? (engineering help)
**URL:** https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965
**Category:** NYSpeed Automotive
**Created:** [July 2, 2009, 4:15am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965 "2009-07-02T04:15:29Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@travisn](https://forums.speedlife.net/u/travisn)
#### Post date: [July 2, 2009, 4:15am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/1 "2009-07-02T04:15:29Z")
I have been wondering how to move a shifter forward and I had a revelation this morning…
edit, I deleted the original picture. continue
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### Author:  [@travisn](https://forums.speedlife.net/u/travisn)
#### Post date: [July 2, 2009, 4:28am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/2 "2009-07-02T04:28:16Z")
nope that wont work, it will want to bend the shifter using the lower left corner as a fulcrum.
Argh.
back to the drawing board.
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### Author:  [@travisn](https://forums.speedlife.net/u/travisn)
#### Post date: [July 2, 2009, 4:34am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/3 "2009-07-02T04:34:03Z")
this?
where the distances between points are the same left to right
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### Author:  [@newman](https://forums.speedlife.net/u/newman)
#### Post date: [July 2, 2009, 4:57am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/4 "2009-07-02T04:57:03Z")
That won’t work with a spherical bearing, as you uggested, but will work with a bearing that provides only rotational DOFs, but your fits have to be very good.
There has to be a better way.
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### Author:  [@travisn](https://forums.speedlife.net/u/travisn)
#### Post date: [July 2, 2009, 4:59am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/5 "2009-07-02T04:59:59Z")
alright, dof?
> A degree of freedom is a single coordinate of relative motion between two bodies. Such a coordinate is free only if it can respond without constraint or imposed motion to externally applied forces or torques. For translational motion, a DoF is a linear coordinate along a single direction. For rotational motion, a DoF is an angular coordinate about a single, fixed axis.
But I would still need a spherical heim joint at the bottom left one to allow both left to right and fore to aft movements, correct?
Where can I ‘economically’ get a bearing type joint? or just make one? (keep in mind I do not have access to any special tools, a drill, grinder, and welder are all I have basically)
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### Author:  [@newman](https://forums.speedlife.net/u/newman)
#### Post date: [July 2, 2009, 5:01am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/6 "2009-07-02T05:01:49Z")
Also keep in mind if you do something like that and fix it to the vehicle, when the trans moves around, so will your shifter… your best bet is to mount to the transmission.
Still thinking about a better way, though.
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### Author:  [@newman](https://forums.speedlife.net/u/newman)
#### Post date: [July 2, 2009, 5:07am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/7 "2009-07-02T05:07:11Z")
> [@travisn](#):
>
> alright, dof?
>
> But I would still need a spherical heim joint at the bottom left one to allow both left to right and fore to aft movements, correct?
>
> Where can I ‘economically’ get a bearing type joint? or just make one? (keep in mind I do not have access to any special tools, a drill, grinder, and welder are all I have basically)
Solid rod ends from [mcmaster.com](http://mcmaster.com)
Plain bearings from the same:
You can use a spherical rod end for the bottom of the new linkage.
Just keep in mind that the resultant force from the moment generated as a result of the side to side action will be substantial, compared to the radial force on the rod ends as a result of fore/aft movement.
What’s this mean to you? Everything has to be TIGHT
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### Author:  [@travisn](https://forums.speedlife.net/u/travisn)
#### Post date: [July 2, 2009, 5:07am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/8 "2009-07-02T05:07:49Z")
Alright, I can attach it to the tranny, no problem
ugh, I wish I had CAD, paint can only go so far… (I have a copy on my computer, but it never completely loads, missing a file I guess)
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### Author:  [@travisn](https://forums.speedlife.net/u/travisn)
#### Post date: [July 2, 2009, 5:10am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/9 "2009-07-02T05:10:32Z")
I think this would be easier, drill out rod, put in bushing, go
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### Author:  [@newman](https://forums.speedlife.net/u/newman)
#### Post date: [July 2, 2009, 5:11am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/10 "2009-07-02T05:11:03Z")
In theory, you only need one “purple link”, but two will be better. The upper one will take most of the fore/aft loading, while the lower one will help change the bending component (using a single rod) to a tension/compression axial load.
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### Author:  [@newman](https://forums.speedlife.net/u/newman)
#### Post date: [July 2, 2009, 5:14am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/11 "2009-07-02T05:14:03Z")
> [@travisn](#):
>
> I think this would be easier, drill out rod, put in bushing, go
2 Problems immediately spring to mind:
1: It’s unlikely that the clevis has the same fits as the solid rod end
2: The bearing surface on the clevis is much less, and by moving the clevis towards the centerline, you increase the bearing forces in it.
The forces you are dealing with are pretty high…
Example:
the rod end is 1/2" wide
the purple link is 10"
It requires 10lb of force to move the shifter to the right
The bearing has a fit worse than .010"
the bearing will see a net load of 200lbsat it’s edges
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### Author:  [@travisn](https://forums.speedlife.net/u/travisn)
#### Post date: [July 2, 2009, 5:15am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/12 "2009-07-02T05:15:36Z")
So, in theory, three would be better?
I dont think I have _that_ much room under there, lol
I still need to learn how to figure out drive line angle so I can determine how high/low the tranny needs to be.
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### Author:  [@travisn](https://forums.speedlife.net/u/travisn)
#### Post date: [July 2, 2009, 5:17am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/13 "2009-07-02T05:17:48Z")
I just cant think of how to use the end you suggested,
For example, I can use a 1" x 5/8" piece of steel and use a clevis to surround it. Idk how to implement the one you suggested in regards to this application.
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### Author:  [@newman](https://forums.speedlife.net/u/newman)
#### Post date: [July 2, 2009, 5:19am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/14 "2009-07-02T05:19:55Z")
I would recommend starting with links with 2 solid rod ends with a bolt in cantilever (shear and bending).
If that still feels lousy, put the bolt in double shear by adding 2 more links to the other side of the shifter.
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### Author:  [@travisn](https://forums.speedlife.net/u/travisn)
#### Post date: [July 2, 2009, 5:20am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/15 "2009-07-02T05:20:03Z")
Or even if I make a clevis out of metal that is 2 inches “tall” (when on a horizontal axis) and the height will take the side to side load forces while the pin/bolt will take the fore/aft forces
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### Author:  [@travisn](https://forums.speedlife.net/u/travisn)
#### Post date: [July 2, 2009, 5:20am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/16 "2009-07-02T05:20:31Z")
> [@newman](#):
>
> I would recommend starting with links with 2 solid rod ends with a bolt in cantilever (shear and bending).
>
> If that still feels lousy, put the bolt in double shear by adding 2 more links to the other side of the shifter.
“bolt in cantilever” “double shear”
yup, not that smart. sorry…
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### Author:  [@newman](https://forums.speedlife.net/u/newman)
#### Post date: [July 2, 2009, 5:42am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/17 "2009-07-02T05:42:45Z")
It’s more complicated than “the height taking the side to side loading” because as you move it side to side, a torsion component generates a moment about the point where the bolt passes through the fifter, that is: the whole thing wants to twist… the further away from the centerline of the shifter you can increase your bearing area, the better.
Clevises (and solid rod ends for that matter) are designed to be loaded axially only, not in bending. However, I think a solid rod end, even loaded in single shear is much more up to the task than a clevis loaded in double shear…
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### Author:  [@travisn](https://forums.speedlife.net/u/travisn)
#### Post date: [July 2, 2009, 5:46am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/18 "2009-07-02T05:46:59Z")
:feck:
laments terms my man. I have not taken one engineering class ever…
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### Author:  [@newman](https://forums.speedlife.net/u/newman)
#### Post date: [July 2, 2009, 5:49am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/19 "2009-07-02T05:49:19Z")
That’s loaded in single shear. The bearing area though, is greater than that of the clevis. If you were to put a second set of rods on the opposite side of the shifter, you put the bolt in double shear.
You can use a clevis, but you just don’t want something with a thin wall section that doesn’t spread the load out away from the shifter centerline
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### Author:  [@travisn](https://forums.speedlife.net/u/travisn)
#### Post date: [July 2, 2009, 5:51am UTC](https://forums.speedlife.net/t/rwd-transmission-linkage-engineering-help/69965/20 "2009-07-02T05:51:06Z")
plus if I use any linkage that is threaded there is a possibility that it will come loose from the left to right movements
fwd cars do it all the time, perhaps I should crawl under my civic and see what is up. pretty sure it uses a clevis type.
see #12
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