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Old 09-23-2017, 03:04 PM   #26
joedoh
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Re: 1946 chevy truck build.

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Originally Posted by Kermitt47 View Post
Is there an acceptable ratio to aim for or is it just to keep the pinion change to a minimum over the suspension travel?
its the latter, unequal lengths will keep the pinion angle and rear steer to a minimum. Just like upper and lower control arms are unequal length, equal length control arms will have MORE camber change, and it will be wacky camber too.

a good way to check this stuff out before even ordering bars is to scale model it with paper first. figure out how far apart (y axis) the bars will be at the front attachment and at the rear axle. then cut some paper strips and use round head fasteners (office supplies) and a hole punch to make an "axle" and "bars" and a "frame"

then you can use a pencil to trace the pinion angle at different heights.
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Old 09-24-2017, 07:26 PM   #27
dillonv2008
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Re: 1946 chevy truck build.

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nope you got it. look from the side and that is the length that matters.
one more question just got the new upper bars in when I go to do the measureing from side view and upper bars need to be the 70 - 80% range. when measuring lower bars length. my lower tab as we talked sticks them forward because they are the shock mount style. question is do I measuring from center axle to front bar link to get my measurement or do I just measure link to link. my lower axle link is forward a few inches from axle.
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Old 09-24-2017, 07:35 PM   #28
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Re: 1946 chevy truck build.

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Originally Posted by Kermitt47 View Post
Hi, I am going down a similar route so this thread is interesting. If you wanted to make the side view equal length then the top bar would have to be longer than the bottom bar? Is there an acceptable ratio to aim for or is it just to keep the pinion change to a minimum over the suspension travel?

from what ive read about the lower and upper bar lengths is you want the upper bar to be about 70-80% of the lower bar length from a side view. dont just cut the bars and make it shorter. its all from a side view. so in my drawing I did the lower bars are parallel to ground and example 30" long center of axle to end of bar link. so my upper bars need to be in the 70-80% range. but the upper links are going to be at an angle so cutting them to early before measuring like I did will make them possibly under that 70-80 range. you have to consider the angle they will be at in your measurments forgetting them in that 70-80 range. so in the example if lowers where 30" center axle to end link. 30-25%= 22.5 but they will be at an angle so you have to add for that angle in your measurments.so the bars them self might really be 25" but with 30* angle or whatever it will from a side view be 22.5 which is 75% of the length of lower bars .. ?? get it kinda I might of made it more confusing haha
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Old 09-24-2017, 08:24 PM   #29
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Re: 1946 chevy truck build.

[QUOTE=joedoh;8041759]if your bar measurement of 13" was related to the bar measurement of the lowers as 21", you still have the problem. measuring eye to eye isnt going to make it better. fix these problems:

your upper bars point down while the longer lowers are straight, this will always cause pinion/roll steer problems. you want them to be close to level when at ride height.

your upper bars are way too short. looking at them from the top this is visible, the upper length looks to be less than half the lower length. you can only measure their length STRAIGHT ALONG THE FRAME, it doesnt really matter what the actual length of the bar is. the effective length, measured straight along the frame, that is how long the bar is. not eye to eye, not just the bar length, all of that is irrelevant. mark two spots on the frame, the centerline of the axle and where the upper bar attaches to the frame and measure straight between those two points. that is the length of your upper bar. if it helps, imagine it as a big rectangular piece of steel instead of an angled bar. even though you can draw a long line from corner to corner of the rectangle, how long the rectangle is measured along one side is how long the rectangle is. thats it.

nvm I reread this and understand center of axle to center link on axle
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Old 09-25-2017, 12:37 AM   #30
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Re: 1946 chevy truck build.

Great progress tonight have front all tacted in place and rear tacted in with only maybe 1 degree change from ride height to on the ground about 6.5 inch of travel
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Old 09-29-2017, 07:46 PM   #31
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Re: 1946 chevy truck build.

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Originally Posted by joedoh View Post
its the latter, unequal lengths will keep the pinion angle and rear steer to a minimum. Just like upper and lower control arms are unequal length, equal length control arms will have MORE camber change, and it will be wacky camber too.

a good way to check this stuff out before even ordering bars is to scale model it with paper first. figure out how far apart (y axis) the bars will be at the front attachment and at the rear axle. then cut some paper strips and use round head fasteners (office supplies) and a hole punch to make an "axle" and "bars" and a "frame"

then you can use a pencil to trace the pinion angle at different heights.

So why does this set up work if from side view bars are equal length. Id Like to redo mine a little so I can run bags on bars.
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Old 09-29-2017, 07:51 PM   #32
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Re: 1946 chevy truck build.

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Originally Posted by dillonv2008 View Post
So why does this set up work if from side view bars are equal length. Id Like to redo mine a little so I can run bags on bars.
since I cant see that going up and down and know that it actually DOES work. but if it does:

bar length. look how long the bars are, longer bars = larger arc of operation = more stable in travel

look very closely. the lower bars are shorter than the upper. this is the same ratio I talked about, upside down.
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Project: Hannah
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http://67-72chevytrucks.com/vboard/s....php?p=8029533


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Old 09-29-2017, 08:06 PM   #33
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Re: 1946 chevy truck build.

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Originally Posted by joedoh View Post
since I cant see that going up and down and know that it actually DOES work. but if it does:

bar length. look how long the bars are, longer bars = larger arc of operation = more stable in travel

look very closely. the lower bars are shorter than the upper. this is the same ratio I talked about, upside down.

So since my lower tabs would go further forward. If I was to attach them to the driveline support I built then from too view I'd want my lower Bars to be shorter in length? The side view center axle to link tab doesn't matter anymore?
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Old 09-29-2017, 10:34 PM   #34
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Re: 1946 chevy truck build.

the unequal length is what allows the stability of pinion angle without fore/aft movement.

if you do what I said above, about mocking it up with paper, use pins as the pivots, you will easily answer these questions for yourself. in engineering we have a saying: "engineers will argue for an hour about something that could be tested in 5 minutes" mock it up with paper, you will be able to simulate longer bars, different attaching points, unequal bars, pinched bars, all of it. literally a 5 minute test. better than that, you will see it for yourself, way better than trying to interpret words on a screen
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the mass of men live lives of quiet desperation

Project: Hannah
my 4.3 5spd S10 41 Chevy 1/2 ton
http://67-72chevytrucks.com/vboard/s....php?p=8029533


if there is a problem, I can have it.
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Old 09-29-2017, 10:54 PM   #35
dillonv2008
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Re: 1946 chevy truck build.

[QUOTE=joedoh;8050799]the unequal length is what allows the stability of pinion angle without fore/aft movement.

if you do what I said above, about mocking it up with paper, use pins as the pivots, you will easily answer these questions for yourself. in engineering we have a saying: "engineers will argue for an hour about something that could be tested in 5 minutes" mock it up with paper, you will be able to simulate longer bars, different attaching points, unequal bars, pinched bars, all of it. literally a 5 minute test. better than that, you will see it for yourself, way better than trying to interpret words on a


True after your help with first part my pinion angle is perfect and everything so I Don't think I'm gonna confuse my self on this. I'll just angle the upper bars further out on axle and in on driveline tunnel. And bring in lower bars so I can run bar on bag. Switching upper bars angles so I can have room to center bags on bars.
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Old 09-29-2017, 11:36 PM   #36
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Re: 1946 chevy truck build.

Quote:
Originally Posted by joedoh View Post
the unequal length is what allows the stability of pinion angle without fore/aft movement.

if you do what I said above, about mocking it up with paper, use pins as the pivots, you will easily answer these questions for yourself. in engineering we have a saying: "engineers will argue for an hour about something that could be tested in 5 minutes" mock it up with paper, you will be able to simulate longer bars, different attaching points, unequal bars, pinched bars, all of it. literally a 5 minute test. better than that, you will see it for yourself, way better than trying to interpret words on a screen
I did the experiment you said to try and with shorter bars on top does what I thought as goes up axle comes down a little.

but when bars where parallel it didn't seem like pinion angle changed at all??
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Old 09-29-2017, 11:43 PM   #37
dillonv2008
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Re: 1946 chevy truck build.

Quote:
Originally Posted by joedoh View Post
the unequal length is what allows the stability of pinion angle without fore/aft movement.

if you do what I said above, about mocking it up with paper, use pins as the pivots, you will easily answer these questions for yourself. in engineering we have a saying: "engineers will argue for an hour about something that could be tested in 5 minutes" mock it up with paper, you will be able to simulate longer bars, different attaching points, unequal bars, pinched bars, all of it. literally a 5 minute test. better than that, you will see it for yourself, way better than trying to interpret words on a screen
Here is the update on driveline tunnel I thought I had posted this already
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Old 09-30-2017, 12:30 AM   #38
dillonv2008
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Re: 1946 chevy truck build.

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Originally Posted by dillonv2008 View Post
I did the experiment you said to try and with shorter bars on top does what I thought as goes up axle comes down a little.

but when bars where parallel it didn't seem like pinion angle changed at all??
ingnore this comment
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Old 02-03-2018, 08:36 PM   #39
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Re: 1946 chevy truck build.

haven't been on here to post anything in awhile so heres some updates.
I have more parts ready to install/mock up but my brake pedal Is wrong one so waiting for new bracket to come in to move further in cab
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Old 02-04-2018, 02:20 AM   #40
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Re: 1946 chevy truck build.

looks good, plenty simple and strong.
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Project: Hannah
my 4.3 5spd S10 41 Chevy 1/2 ton
http://67-72chevytrucks.com/vboard/s....php?p=8029533


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Old 02-04-2018, 02:26 AM   #41
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Re: 1946 chevy truck build.

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looks good, plenty simple and strong.

thanks if you look in picture where the back of c notch is I'm gonna do some reinforcing doesn't look strong enough to me haha.
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