[ebartone]

Hello everyone, after putting in my new S 60, complete with Spohn double adjustable upper and lower control arms with Delron spheres, I’m thinking a lot about pinion angles, and reading a lot about this. Please correct me if I’m wrong, my understanding is that my goal is when I take off the line, my rear pinion comes up and then ideally becomes parallel with the transmission. So for me, my transmission is pointing downhill towards the back of the car at about 4.5°. I have moved my rear angle so it’s basically aiming up about 4.5° back to front currently, so it is now parallel with the transmission. This results in a driveshaft that’s heading downhill towards the back at about 1.5°, and both of my u joint angles Are around 1.5 to 2°. My question is, am I going about this the wrong way? I get that during acceleration pinion wants to come up, however, if you have a completely rigid suspension, does it really come up at all? If it doesn’t, shouldn’t I set the pinion in rear end parallel to the transmission right from the get-go? Thanks.

[performerrpm]

i struggled setting mine up, since my original ride height set my rear dif higher than the trans...now thats changed but at the time,all the reading and talking to chassis guys i set my car up the first time with 2.5° pointing down at trans, and my pinion was aimed up 1.5° up in hopes that the ladder bar would only allow 1 to 1.5° axle wrap. i think a straight 0° ujoint angle is ideal under load but depending on ride height that may not be possible. at the very least the u joints working angles need to be at opposite but equal ° to counter act each other. 2 me it looks like atleast going by the sketch you posted and the 4.5° and the 4.2° pinion angle you may have a vibration. I think you would need to start with the pinion at 3° in targer for 4.5° after wrap. otherwise i would think if you start with 4.2° pinion angle you may end up in the 5° area.

im hoping to read others comments on this though since i mighta got mine wrong....

[ebartone]

Really interesting, thank you. My only thought, and I could be wrong. Obviously, I’m just learning this as I go myself, is that all of my control arms I’ve replaced with Molly and Delron sphere joints. I only mention this, and the triangulation brace, because can the axle actually wrap with this very firm set up? I get it if I have rubber or poly bushings there is certainly room for wrap, but from what I’ve read, these guys really won’t give. I haven’t driven the car yet, it’s waiting for this winter to be over. But my thinking is if that’s true, and it cannot wrap, then now I am fixed at essentially parallel to the transmission, which is what I wanted, especially when I launch.

But it’s easy enough to bring the pinion down a couple degrees. Thank you for the advice, definitely looking to learn also.

[performerrpm]

i cant say for certain since i havent actually ran my ladder bar suspension yet but....the way i understood it my ladder bars probably allow the least amount of axle wrap because the 3 mounting points, and less movement in that paticular area. your trailing arms even though they will make a overall better ride/ even easier adjustments will probably have a little more room to give even if its just another 1° more

[ebartone]

I think this video is pretty good, basically the way I read it, I need to get to my full 4.5 at launch, so roughly I need to be at about two resting, so this means I need to bring my rear angle down to about two or 2.5°.

https://www.youtube.com/watch?app=de...VFyFdvEs&t=414

[ebartone]

Thanks, performer, I can see your point. I think my misunderstanding initially was that I thought I needed to have the resting angle of the rear pinion parallel to the resting angle of the transmission. As you can see, that’s basically what I set up. What I should have done is the launch angle needs to be the same, so if I assume 2° or so of wrap, then I need to bring my rear pinion down to about 2° up.

[performerrpm]

i think you coukd go 2 -3° uo on pinion and then test it. i bet you will have to play with it a bit but i think your onto a good start

[Keith Seymore]

Originally Posted by ebartone

Hello everyone, after putting in my new S 60, complete with Spohn double adjustable upper and lower control arms with Delron spheres, I’m thinking a lot about pinion angles, and reading a lot about this. Please correct me if I’m wrong, my understanding is that my goal is when I take off the line, my rear pinion comes up and then ideally becomes parallel with the transmission. So for me, my transmission is pointing downhill towards the back of the car at about 4.5°. I have moved my rear angle so it’s basically aiming up about 4.5° back to front currently, so it is now parallel with the transmission. This results in a driveshaft that’s heading downhill towards the back at about 1.5°, and both of my u joint angles Are around 1.5 to 2°. My question is, am I going about this the wrong way? I get that during acceleration pinion wants to come up, however, if you have a completely rigid suspension, does it really come up at all? If it doesn’t, shouldn’t I set the pinion in rear end parallel to the transmission right from the get-go? Thanks.

Your analysis is sound and correct, assuming you took your measurements with the suspension loaded (with the weight on the wheels or on the axle). You want the u joint working angles to be equal and opposite.

Regarding windup - a leaf spring car will wind up two or three degrees during launch. I cannot imagine your four link set up will wind up more than half a degree.

I would recommend you add a half degree windage to accommodate if you are comfortable doing so.

K

[ebartone]

Thank you, Keith, trust me it was laying flat at drive position, as I tried to maneuver my fat butt around underneath the car to make adjustments and take measurements! Appreciate your comment.

[ebartone]

Hello everyone, I would like to bring this topic up again, because I’m not feeling very confident I have the right answer. And possibly too much time in the Michigan winter when I can’t really do anything with it anyways is the problem, so I think about it too much! But the bottom line is it sure seems to me there are two different philosophies on how to do this, and videos and arguments for each one being valid. The first one, see my picture, is what I have now, wear basically the pinion and the transmission angles are the same, in parallel. This is what I have now, so I have my opinion sticking nose up about 3.1°. The second argument is basically ignore the engine angle, as long as the U joint, of course is at a healthy couple degrees, but angle opinion down such that on launch it comes up in direct line with the driveshaft. Again, take a look at my two drawings to see what I mean, I can easily change between the two, and maybe I should just wait until spring and see if it vibrates, But maybe the reason for two different philosophies is the use, I really want to mostly set it up for racing, but be treatable as well. Any thoughts are always welcome. Thank you.

[ebartone]

by the way, the reason my numbers are slightly different from my original posting, is I have since purchased a decent electronic angle finder so I’m a little more confident in my measurements now.

[ebartone]

Apologies, clearly the angle that I put on my drawing between the transmission and the driveshaft is incorrect, it should be 1.6.

[Keith Seymore]

Originally Posted by ebartone

Hello everyone, I would like to bring this topic up again, because I’m not feeling very confident I have the right answer. And possibly too much time in the Michigan winter when I can’t really do anything with it anyways is the problem, so I think about it too much! But the bottom line is it sure seems to me there are two different philosophies on how to do this, and videos and arguments for each one being valid. The first one, see my picture, is what I have now, wear basically the pinion and the transmission angles are the same, in parallel. This is what I have now, so I have my opinion sticking nose up about 3.1°. The second argument is basically ignore the engine angle, as long as the U joint, of course is at a healthy couple degrees, but angle opinion down such that on launch it comes up in direct line with the driveshaft. Again, take a look at my two drawings to see what I mean, I can easily change between the two, and maybe I should just wait until spring and see if it vibrates, But maybe the reason for two different philosophies is the use, I really want to mostly set it up for racing, but be treatable as well. Any thoughts are always welcome. Thank you.

You want the u joint working angles to be equal and opposite under load.

It's the only "philosophy" that works, because it's the only one the physics supports.

Each time u joint passes the tightest spot it give a little "kick" in the rotational acceleration of the shaft. If you have the opposing joint at the same working angle then it has a corresponding "anti kick" at the same time, canceling it out.

What is negotiable is a) how much error between the two you want to allow, and b) how much "windage" you want to put in there measured statically vs what you think the rear axle pinion nose windup will be, based on your rear suspension type.

The only other option is to go to a couple constant velocity joints, which can be done but is more than you want to get into I presume.

K

[Keith Seymore]

PM sent.

K

[turbo69bird]

Keep this in mind when setting pinion angle. Ladder or 4 link style suspensions squat
Slapper bar style leaf spring cars seperate. Two opposite movements. You rarely if ever see this addressed. . I’ve never (knocking on wood here) kicked out a drive shaft on my stick cars even leaving at 6400 RPM w a slapper bar car. While most people I know have. I attribute that to 2 things. Thinking about how my car separates on take off or squats , and Lakewood solid U joints lmao

BTW I’ve also run then same Lakewood U joints in one of my cars since the early 90s !

[AG]

With your current numbers your pinion angle is -1.5 degrees. If you estimate that you will have 1.5 degrees rotation up with your pinion you are at the right place. If you estimate no upward pinion movement then you need to move your pinion up 1.5 degrees. The working angles need to be the same under load, if your trans is 3.1 degrees down, your pinion needs to be 3.1 degrees up under load. I have Caltracs and use 2 degrees down on my pinion compared to my trans and that has worked well for me, I think Calvert recommends 2-2.5 degrees for leaf spring cars with Caltracs.

[performerrpm]

Originally Posted by turbo69bird

Keep this in mind when setting pinion angle. Ladder or 4 link style suspensions squat
Slapper bar style leaf spring cars seperate. Two opposite movements. You rarely if ever see this addressed. . I’ve never (knocking on wood here) kicked out a drive shaft on my stick cars even leaving at 6400 RPM w a slapper bar car. While most people I know have. I attribute that to 2 things. Thinking about how my car separates on take off or squats , and Lakewood solid U joints lmao

BTW I’ve also run then same Lakewood U joints in one of my cars since the early 90s !

this threads kinda got me re thinking my settings now lol.....luckiky i have to make some ride height changes and will re check/adjust on the lift after paint.im hoping to keep my rear suspension movement kept to within a inch on launch ...but its a blown 4 speed car so we will see how that works out.

[ebartone]

Thanks, everyone, and Keith I tried to PM you back, but I can’t see anything in my sent so tell me if you did not get it.

Also, if anyone is interested, this is the angle finder, it was not expensive and seems pretty repeatable, I’m only assuming it’s accurate.

https://www.amazon.com/Klein-Tools-9...03&sr=8-5&th=1

[ebartone]

So thanks everyone for their response, it sounds like I’ll just leave The where it is, and see how she does. Also, I’ve read about phasing, does it matter the relative position of the U joint in the trans, compared to the rear end?

[ebartone]

Thanks, AJ, you could tell from the drawing, that my rear end is pinion up, aiming towards the front of the car, correct, or stated differently, front to back it would be coming down. Thanks again.