Thread: Old question....new problem...drive-line angles? Sorry.

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Guys,

I've had several people tell me that the ideal drive angle for my combination....4L60E and C4 IRS would be between 2.5 and 3 degrees. The rear end wont be any problem....but darn if the transmission is close enough. I'm at 5 degrees. I cant raise the transmission any more....and cant lower the motor without notching the top of the frame (A/C clearance). I really dont want to go with a different pulley system. I know to angle the rearend pinion at 5 degrees opposite of the transmission so theyre center lines are parrallel. No problem there. But.....do you see any drive line problems down the road for me? I'm not going to mind replacing u-joints....but just wanted some thoughts before I commit to finish mounting the rear end.

Also, I think I found the answer by doing a search but I still want to ask. I plan on cooling the transmission with nothing but a pair of dual pass 18" heat sink style coolers from Jegs. Think it will be suffient enough? I'll be placing them on the inside of the frame rails....away from the exhaust. My exhaust is going to be under the running boards....of all places. There actually is plenty of room.

Thanks,
Dave

Five degrees is no problem, as long as you do the rear pinion up the same amount. My Jeep was steeper than that, and ran fine.

As for the coolers, one should work, but if you feel better with two, go for it.

Don

Originally Posted by Itoldyouso

Five degrees is no problem, as long as you do the rear pinion up the same amount. My Jeep was steeper than that, and ran fine.

As for the coolers, one should work, but if you feel better with two, go for it.

Don

Thanks Don. My Jeep also was much worse...like 15 degrees...and I really didnt want to sound ignorant but I felt more comfortable hearing it from you guys....the ones that have 'been there done that'. Nothing is more unsettling to me than the thought of having to cut into my fresh painted frame.

Thanks,
Dave

I agree with Don. However, there are two other angles you need to be concerned about. Those are the angle between the driveshaft and the centerline of the crankshaft and the angle between the driveshaft and the centerline of the pinion. They need to be within limits also.

For example, if the engine were high enough in the chassis, it would be possible to have 5* down on the engine, 5* up on the pinion, and have the crank directly in line with the pinion. That would not be good.

This article gives some good ideas:

http://www.streetrodderweb.com/tech/...les/index.html

Originally Posted by Henry Rifle

I agree with Don. However, there are two other angles you need to be concerned about. Those are the angle between the driveshaft and the centerline of the crankshaft and the angle between the driveshaft and the centerline of the pinion. They need to be within limits also.

For example, if the engine were high enough in the chassis, it would be possible to have 5* down on the engine, 5* up on the pinion, and have the crank directly in line with the pinion. That would not be good.

This article gives some good ideas:

http://www.streetrodderweb.com/tech/...les/index.html

Oh my gosh Jack. Thats what I was looking for. I totally forgot my working angle. Crud! I knew there was something I was forgetting. I cant tell you enough......thanks!!!!!

My trouble....because of a multitude of angles....I'm starting to get in deep. The rears are 28"...the fronts 22.5"....about 3 degrees of rake in the frame....transmission has 5 degrees of down angle and is much lower to the ground than the rear. Wish I couldve found my "Doorslammers" book. I knew I was forgetting something. I'll have to take some measurements tonight and plot it on paper. This might be a good thing for me ...or bad...

Thanks,
Dave

Dave

the angle to the world/ground referance means nothing----the relative angle of the trans output shaft/drive shaft /pinion shaft are the angles that matter---perfectly straight with each other on causes u joint wear as the needles don't rotate, whereas too much angle causes vibration----the desired u joint angles can also be obtained by horizontal(sideways) shifting of engine/trans or rear differentials---on your C4 rear this wouldn't be easy---

Something new might be to use one of the new type driveshaft couplers that are on the new GTO, Mopar hemi or Ford Mustangs

"....transmission has 5 degrees of down angle and is much lower to the ground than the rear."

This right here tells you that all will be well because the trans output shaft and pinion can't be pointing toward each other if the trans shaft is lower. The driveshaft will be running upward as it goes to the rear and that's ok too, just as long as, like you said, you have the trans output shaft and the pinion parallel with each other.

I'll try to reply to everyone. Wow. I couldnt find my "Doorslammers" book. But listening you guys are a huge help. I did find some software (with a free 15 day trial) with a correction angle tool built in. I believe its for locating and correcting excessive driveline harmonics asssociated with multiple things. It seems to work very well.

Guys, I guess why I'm confused is all the different things I've read in the last week. Some say no more than 3 degree working angle for the transmission and the rearend. Some say 4-5 degrees. Then there is operating angle....difference between trans and driveshaft....and difference between pinion and driveshaft....the two should have between .5 and 1 degree difference in each other. Someoneelse told me 0 degree and that they should cancel each other.

Tonight....where I had everything set initially. The pinion was 12.75" to ground with an up (toward engine) angle of 2.5 degrees. The driveshaft was angled down at 2 degrees. The output shaft of the trans was 11.50" to the ground and an up angle of 5 degrees. LOL's. I use to love the problem solving math tests in school....now my brain is spinning.

I think now I have it corrected. I raised the end of the transmission 1". This placed the driveshaft at 0 degrees and the trans shaft at 3 degrees and 12.5" to the ground. Looks like I may have her whooped! But now I have to cut out the floor pan (under the seat riser) to make clearance for the tailhouse. Darn. Oh well. At least I get to keep the factory pulleys on the LS1. There was no way to lower the engine any more without clearance problems.

Heres a link to that software for anyone that want to piddle with it. http://www.vibratesoftware.com/



Dave

Originally Posted by jerry clayton

Dave

the angle to the world/ground referance means nothing----the relative angle of the trans output shaft/drive shaft /pinion shaft are the angles that matter---perfectly straight with each other on causes u joint wear as the needles don't rotate, whereas too much angle causes vibration----the desired u joint angles can also be obtained by horizontal(sideways) shifting of engine/trans or rear differentials---on your C4 rear this wouldn't be easy---

Something new might be to use one of the new type driveshaft couplers that are on the new GTO, Mopar hemi or Ford Mustangs

Jerry,

Unfortunately, the C4 is offset nearly an inch....and I have no more room to move transmission over to correct for it. I also have no way of figuring out the measurement on a horizontal plane without knowing exactly where the crank/output shaft center line is....maybe an laser of some sort. Hmmm. Am I being too picky? Are the GTO, Mustangs your talking about using a sort of double cardin design? Or a split shaft? I tried to do a search to see what you were talking about.

Thanks,
Dave

You are making this way too hard on yourself...........it isn't Rocket Science. Just put a protractor on a flat surface of your transmission (usually the end of the tailshaft has a flat, round section that is the same angle as the crankshaft line) and get whatever number that is. Lets say it is 5 degrees. Then simply aim your rear end pinion up until your protractor reads 5 degrees up on a similar flat surface.

That's all I have ever done, and I have never had any driveline wear or vibrations. Sometimes volumes are written about something that only needs a sentence or two written about it. Trust me, have I ever lied to you?

Don

Originally Posted by techinspector1

"....transmission has 5 degrees of down angle and is much lower to the ground than the rear."

This right here tells you that all will be well because the trans output shaft and pinion can't be pointing toward each other if the trans shaft is lower. The driveshaft will be running upward as it goes to the rear and that's ok too, just as long as, like you said, you have the trans output shaft and the pinion parallel with each other.

Out of all of that I've learned in the last week.....it has finally sunk in....want to be between .5 and 1 degree of perfectly parallel on my driveshaft center line and transmission centerline. Thanks everyone.

You know....why does Spicer....and several other sites state that anything beyond a 3 degree working angle is unacceptable? I see trucks/jeeps with much more than that all of the time? I understand the reasoning behind being parallel but unsure of where they get the 3 degree cut-off for working angles. Puzzled.

I guess in a perfect world....because the IRS center section is stationary....if it were directly in line with the engine it could be coupled direct without u-joints? Unless slight engine movement on the mounts would mess things up? Just guessing out loud.

Thanks,
Dave

Originally Posted by Itoldyouso

You are making this way too hard on yourself...........it isn't Rocket Science. Just put a protractor on a flat surface of your transmission (usually the end of the tailshaft has a flat, round section that is the same angle as the crankshaft line) and get whatever number that is. Lets say it is 5 degrees. Then simply aim your rear end pinion up until your protractor reads 5 degrees up on a similar flat surface.

That's all I have ever done, and I have never had any driveline wear or vibrations. Sometimes volumes are written about something that only needs a sentence or two written about it. Trust me, have I ever lied to you?

Don

Ha Don. Sorry. I think I've been reading to darn much.....making rocket science history you know! I do believe I finally have this figured out. You guys have me convinced. I was just worried about that 3 degree working angle and beyond.

Thanks,
Dave

If you look at what some of the jacked up four wheel drive guys are running for driveline angles, 5 degrees is a walk in the park comparatively. All kidding aside, you will be fine, U joints are very forgiving.

Don

After rereading your posts, it looks like you may have been taking angles relative to the ground??????the only angles relative to the pinion c/l and crank/tailshaft c/l mean anything
Since the C4 rear is stationary and doesn't move around like a normal rear you probably won't have much of an issue---if the rear end moves up and down, then you have to maintain some angular limits--
The newer drivelines I wrote about are kinda like the rag joints on a steering shaft but different--

Rule of thumb (this one actually works) one in sixty-----one inch offset in a 60 inch drive shaft equals ONE DEGREE----and if you are flying one degree off course for 10 hours at 600 MPH you will miss your (pick one) destination,target,checkpoint,refueler,etc by 100 miles, corse if the bomb is big enough-----

Originally Posted by jerry clayton

Rule of thumb (this one actually works) one in sixty-----one inch offset in a 60 inch drive shaft equals ONE DEGREE----and if you are flying one degree off course for 10 hours at 600 MPH you will miss your (pick one) destination,target,checkpoint,refueler,etc by 100 miles, corse if the bomb is big enough-----

Jerry, I think this story has a moral::: If you can't fly straight, carry a big bomb????

PS--Used to love to watch them drop them great big "daisy cutters"!!!! Instant LZ free of jungle critters....


Didn't mean to derail the thread, sometimes it's amazing how my mind works, or doesn't!!!!!!!!!!