4 link an pinion angle

[Cartelpaintshop]

I'm doing a back half with 4 link I don't know how to set the pinion angle an as for the 4 link how are the tabs and link set rear end
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[Ziegelsteinfaust]

The bars should be aimed at ride height to a mystical place 18" in front of your bumper, and this typically offers the best IC. The 4 link tabs should be vertical to the ground at ride height including rake. Most bars have some adjust ability to help out for tolerances.

[Cartelpaintshop]

Thanks that helps alot the pinion angle how do i set that up
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[Robznob11]

You can get into very large arguements over the best way to set pinion angle! If you google it there is a great write up i dont remember the guys exact name but im pretty sure it starts with an o. Pinion angle is set at ride hight on the tires you will be running and on level ground. Angles are referanced to the ground not the shaft. I know most shoot for the pinion to be 2 degreese down because the gears will climb but i believe it is also referanced to the degree of the tranny. In other words if the tail shaft was 1 degree up from level ground then the pinion would be 1 degree down = -2*. Some say you level the frame and referance it but i think the other way is correct because rear tire size affects angle. As im typing this the name ohare keeps coming up. Ill try to find his link. Because there are lots of geomotry things to consider. And purpos has alot to do with it. Mos cars and tks have a tranny with a neg angle. Race cars are set up tranny positive for weight and traction issues. Hope i did not confuse you worse!! Lol
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[wraprail]

Tire size has nothing to do with pinion angle. You have to check the angle of the trans output shaft so you can't do it with the truck sitting on the ground. With the cab off you could. Anyway, whatever your trans tailshaft angle is (should be somewhere close to 3 degrees down) you want your pinion to be the same angle only angled up (opposite) somewhere close to 6 degrees total is ideal. This is at ride hight. If you set up your 4 link correctly this angle will change very little through the range of travel. I just did a triangulated 4 bar on my c10 and get 1 degree change.
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If you have an IPhone they have some very good angle finders in the app store for free. You can also pick one up at lowes. Check the trans from the end of the output shaft (remove driveshaft) and pinion you can use the flats on the yoke again with driveshaft removed.

[69gmcc10]

read this, it has everything you need to know about drivelines, transmissions, pinions, there angles, relationships and how to set them.

http://www2.dana.com/pdf/J3311-1-DSSP.pdf

You should have the weight on the suspension when you set your pinion angle. Tire size doesnt make a difference, but a difference in tire size from front to back does if it effect the rake of your vehicle. The change in rake has can effect the angle that your engine should operate at, leaning 3-4 deg back (output shaft down) to help with bearing wear. from there all of the information you need to know is in the pdf reffed to above. Your 4 link should have allot of adjustment to get the perfect pinion angle when all bolted up, just do your best to get it as close as you can when you go to burn it in during mock up.

[Robznob11]

I have read so may writings on the subject today because this is still something I need to tackle. I could not find the ohare reading again but I did find a site with part of it. they argue that you have to know the tire size and be on level ground. and not to measure relative to the frame. now after many readings I find one solid reaccuring theme. you want the tranny output angle equal but opposite to the pinion angle and the go down on the pinion about 2*. and you want the total angle between driveshaft and pinion or tranny to be 5* or less to keep u joints happy. a good example of not good would be a 4x4 jacked up the tranny could be equal and opposite of pinion but the total angle of the u joint would be outside of a safe operating range therefor not lasting long and probably causing vibrations. I cant understand why rake would even affect angles, unless they are taking into consideration other geometry factors like ic and weight transfer. and overall performance of the suspension. I mean if your parked on a 45* slope other than slight spring compression from weight the pinion,shaft,and tranny are bolted into place and relation to each other as far as angles should stay the same. sure on a gauge they may be way different but if they are set at 4* apart they should still be that. example tranny 45*+ pinion 43*+ witch is still nose down 2*. am I crazy or what. I have discussed this stuff on another thread and it turned into a mess. I was given some info that was specific to my truck and I did not make that clear. most people assume that you are running about 3* down on tranny where the factory tends to set it. but I installed my motor with home made mounts in my ideal location and that affects my whole set up. anyhow I need to hush im not trying to jack your thread

[69gmcc10]

"I cant understand why rake would even affect angles, unless they are taking into consideration other geometry factors like ic and weight transfer. and overall performance of the suspension. I mean if your parked on a 45* slope other than slight spring compression from weight the pinion,shaft,and tranny are bolted into place and relation to each other as far as angles should stay the same. sure on a gauge they may be way different but if they are set at 4* apart they should still be that. example tranny 45*+ pinion 43*+ witch is still nose down 2*. am I crazy or what."

I think you are absolutely correct on this. In my searching for answers on the issue I have found that the only reason rake is brought up in subject when talking about driveshaft and pinion angles is to remind people that it is present and it has nothing to do with drivetrain angels because they are in relation to the earth and each other, that's it. I guess it is the more complicated way of saying to "not" base your angles by referencing the frame, but to how your drivetrain is positioned in your car as the vehicle sits on the ground.

[Ziegelsteinfaust]

Rake as I mentioned is to be considered as fully part of ride height. Most people run the back end of there vehicle about a inch higher then the front, and that is why it is a consideration of ride height.

So if you go to set you ride height with the vehicle perfectly level, or with it to high in relation ship to what your goal is. Then your pinion angle changes will need to be larger, and more cumbersome. Also you 4 link bars could be pointed to high, to level, and worse pointed down.

Also with your IC off rather for daily driving, road racing, and drag racing. You could run into issues when you push it far enough, and if your back halfing your truck I think big HP is in the cards.

[98layinframe]

Its simple.. if the tranny is pointed down at 3°, the point the rear up around 3°. Its set at equal but opposite.
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[Robznob11]

Originally Posted by 98layinframe

Its simple.. if the tranny is pointed down at 3°, the point the rear up around 3°. Its set at equal but opposite.
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My .02 yes sir it is that simple. You will want to point the pinion nose down a couple extra* to compensate for the diff gears climing and rotating the pumpkin up! But if you block the truck under the tires on pretty much level ground and pull your mesurements. Rake and everything else do not matter if that is the wheel tire package you are running for good. Now if you have two donuts on front and 33" slicks on back and set it, yes i could change slightly when you put 22s all around but only from the weight transfer compressing the springs. And most people have enough common sense to know not to do something that drastic lol!
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[wraprail]

All this talk about rake and tire size, you know how many degrees change in pinion angle you will see with one inch of rake? Zero. You would have to be way off level to see o e degree change. Try it. Put your angle finder on the trans output and start jacking the back up. Just set the frame at your projected ride hight and build off that. Thats how its done
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[Cartelpaintshop]

Thanks for all the info one more thing i got the frame with no cab or trany it has 3 inch z how would I set the pinion and find the i c I'm doing triangulated 4 link if the bars are the sames size would it matter
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[wraprail]

I'm doing my frame Z with triangulated four link right now too. Check out my build thread. I started from scratch as far as motor/trans mounts and pinion angle. I'm also using a 9 inch. I already knew I was going to put 3 degrees pinion (6 total) angle so I started on the rear end and did the motor mounts and trans crossmember last. Mounted the motor as low as I could (balancer .5 inch above center link) and set crossmember to get my 3 degrees ( down). Looks funny with most of the trans sitting above the frame rails but thats where it goes. My Z is only 2.5". Used a drop trans crossmember for exhaust clearance.
To answer the questions, set your pinion and trans at 3 degrees at ride hight with your four bar adjustable ends leaving some adjustment. You can also shim the trans mount later if something comes out crazy. Just relax and do it. It's only metal. ....
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