1946 chevy truck build.
 

i have a 1946 chevy truck. my plans are 4 link in rear. ifs front end swap. v8 swap. and bagged almost to floor boards while keeping patina look.

ive been looking all over and havent come across anyone that has a build page of them doing this to one of these trucks just few pictures of some already done.


already have a donor motor taken down to block and in machine shop getting hot tanked. waiting for the block back and all the new parts for the motor.

after sittting for over 20 years only a small amount of rust on driver fender nothing to big or crazy though

Re: 1946 chevy truck build.
 

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Re: 1946 chevy truck build.
 

Looks like a good start...joedoh may try to take it away from you..he seems to be hoarding trucks these days..haha

Re: 1946 chevy truck build.
 

check out my build page. Good luck.

Re: 1946 chevy truck build.
 

man I need a nice donor like this to start with. all of mine are 40% iron oxide.

Re: 1946 chevy truck build.
 

Sorry for the late update just got done rebuilding the motor for this guy came out pretty good next weekend I'll fire it up hopefully a smooth break in

Re: 1946 chevy truck build.
 

dude Chizzler I gotta to see that truck in person one day..

I'm just seeing this post for the first time for some reason, sounds like the makings of a great build. Any other photos so far?

Re: 1946 chevy truck build.
 

Non so far I've been busy working and remodeling are new house maybe in another month I'll be able to work on it. But I have oreded and have rims and tires. Crags 69 with 2.38 white wall tires. Ifs m2 with air bags, 4 link for rear, air line and air bag parts. I have almost all the parts to do full suspension just don't have the time right now. Very soon though I'll be getting into it I hope..

Re: 1946 chevy truck build.
 

Update. I've removed old engine and have started the ifs install

Re: 1946 chevy truck build.
 

Need some help. I feel my 4 link is getting too much pinion angle change.
Ride height is 6.5 inches off the ground have it set at +3 for pinion angle. When aired down goes all the way too -6 degrees and i believe around +1 or 0 aird all the way. What did I do wronf?? My lowered are parallel with floor. My uppers are -3 , IC being at firewall. Lower bars are 21 inches bars alone. Uppers. 13 bars alone.
Need some help figuring out why this is getting so much pinion angle change

Re: 1946 chevy truck build.
 

your uppers are not 13 inches long measured along the frame, only measured along the bar itself. my guess is they are 9-10 inches long measured in the same plane as the lowers. your forward attachment point is less than halfway along the lower, you are going to have lots of pinion angle change. you will also probably notice the axle moves forward in the wheel arch quite a bit when aired out too.

this is why I recommend tacking the suspension together and running it up and down a few times, like you have. good work.

you should probably get longer uppers or reduce the angle on them to make them longer in relation to the lowers, because even if you resign yourself to driving only at drive height and accepting the pinion angle change as it gets lower, you need to be aware of something called "rear steer". measure from the axle centerline to a fixed point on the frame, then jack up just one side of the axle (like if the wheel was going over a bump) on the side you have jacked up you will notice the measurement gets shorter and the opposite side (which is pushed down) will get longer. this steers the truck from the rear suspension and is a way to have some crazy handling characteristics in corners. steering force applied at the end of the chassis is more unsettling than forces applied closer to the center of gravity (imagine a shipping container on grass. push in the middle and it probably wont move, push at the ends and you will be able to spin the container)

looks really nice so far!

Re: 1946 chevy truck build.
 

Yes it does roll forward when going up into frame. So I should set the uppers around 35*? They are at 45. The bars came all 4 same length 21" I believe. I cut uppers so they are 75% I believe they are 13 something I'll get better measurements once home. With link ends In idk what total length they are. @joedoh

Re: 1946 chevy truck build.
 

Also I have my IC set around firewall and upper bars about 3* down is that about right or should they be level

Re: 1946 chevy truck build.
 

I am not saying your bars dont measure 13", I am saying in the plane viewed from the side of the truck, the bars will be much shorter than 13", more like 9 or 10 effective length. make a mark on the frame at the axle, then measure forward to where the bar attaches, it will be 10 inches or less. this is all that matters in bar length, effective length. I could have a 70" long bar set at a 1/2 degree angle from the rear axle and the effective length would only be 2".

did you buy a parallel link and switch it to triangulated? all 4 21" sounds like a parallel 4 link setup. either way, to manage pinion angle change you need to get the bar lengths within about 80% of each other. so for a 21" bar that is 17" effective length. thats about how long it would be if you took a 21" bar and mounted it at an angle for a triangulated setup.

Most guys put the upper bars down because that is what the frame allows, but having them already at a down angle when the bottom bars are level means you will have lots of pinion angle change. Its true that "pinching" the front of the bars together (upper pointing down slightly to roughly level lower bars) changes IC. but with adjustable suspension I would recommend to try getting your pinion angle change and roll steer good and worry about IC as a secondary concern.

Re: 1946 chevy truck build.
 

Gotcha gotcha i understand know. So are you saying I should have my uppers level though with lowers at ride height? And also take them away from 45 and get more of a 30 so I get more frame length from uppers correct

Re: 1946 chevy truck build.
 

just measured if looking at a side view how much bar is used center of axle to link. and 13" the bar it self is 13 3/4 long. at the adjustment I have end links in are total 17" center eye hole to center eye hole

Re: 1946 chevy truck build.
 

also my lower bar brackets from axle are pushed forward and back of it is vertical up and down that a shock would mount too. my question on that is should the bracket be where the bar link is under the axle or is it fine that it is pushed forward infront of axle. it is level with ground, lower bars

Re: 1946 chevy truck build.
 

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.

the upper arc of operation will be a much smaller diameter circle than the lower arc of operation, so the lower mount will stay roughly stable in up/down motion while the upper will not, it will move forward and back dramatically.

having the lower bar mount kicked forward of the axle centerline is pretty standard for 4 links, especially with a shock mount on the rear.

edit: I just rotated and enlarged your picture so I could see better and it looks like you are welding to the cast part of the rearend. this will probably break under use, welding to cast is possible if you preheat it with a torch and get it cherry red but it takes special rod too.

Re: 1946 chevy truck build.
 

I understood what you mean. Not length of the actual bar but from centerline axle along frame rail to the link where it attached to the frame. That was indeed 13inchs. I was just saying the specs of the bar itself in post about length of lower and upper bar actual spec length. But I removed the upper bars and going to be re angling them around 30sih degrees or so and parallel with lower bars at ride height. I'm ordering new tab links because old ones didn't make the tear down haha. So when New ones come in I'll go ahead and do what you said. Also I'll mount them on the axle them self not the pumpkin part as you are saying can't be done unless special measures are taken.

Would I get a better pinion angle stability of staying still if I was to just do a reverse 4 link? And order longer upper bars?? Or if I do what you are saying of pushing angles not so wide and level I will see a much better and practical ride. I want to be able to drive at it slammed for shows or streets. So all angles id like no issues with driveline u joints going out

Re: 1946 chevy truck build.
 

I took a 2ft framing square and set it on my axle center. Along frame rail to link and measured 13"

Re: 1946 chevy truck build.
 

I think I'm starting to under stand a little so I want from a side view. my upper bars to be around 20-30% less then lower bars. so if I was was to measure from axle to the link on the frame staying along the frame rail and my lower bar was say 30" id want my upper bar to be around 25" say. BUT the actual spec length of the bar doesn't matter only what you measure from a center axle to the link along the frame rail. and where ever that mark lands I go out 30* + to axle. idk if this is really really confusing or not haha in the picture I want lower bars to be longer then uppers but measure from side view not top.

Re: 1946 chevy truck build.
 

nope you got it. look from the side and that is the length that matters.

Re: 1946 chevy truck build.
 

[QUOTE=joedoh;8041849]nope you got it. look from the side and that is


Awesome thank you so much

Re: 1946 chevy truck build.
 

Also for setting pinion angle am I setting it up +* or -*? Since at ride height I'm only 6 inches off ground the transmission is angled down lower then the axle is gonna be. I guess what I'm asking what did you set yours at at ride height. My motor isn't installed yet so I can set that to what I'd like aswell - something

I do understand you want it to be opposite. -3 tranny +3 axle yatta yatta yatta. So if my axle at ride height is as high or higher then transmission angle am I still going +??

Re: 1946 chevy truck build.
 

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?

Re: 1946 chevy truck build.
 

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.

Re: 1946 chevy truck build.
 

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.

Re: 1946 chevy truck build.
 

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

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

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

Re: 1946 chevy truck build.
 

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.

Re: 1946 chevy truck build.
 

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.

Re: 1946 chevy truck build.
 

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?

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

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.

Re: 1946 chevy truck build.
 

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??

Re: 1946 chevy truck build.
 

Here is the update on driveline tunnel I thought I had posted this already

Re: 1946 chevy truck build.
 

ingnore this comment

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

Re: 1946 chevy truck build.
 

looks good, plenty simple and strong.