Brake rotor centering

[GregWeld]

Trey ---


One of the things that gets messed up is trying to make it too complicated....


And remember that you want the PINION angle DOWN -- because as the power is put to the rear end - it tries to rotate the pinion UPWARDS.... The type of suspension you have makes a difference in how much this is allowed to rotate from a "negative" to the positive. A race suspension which allows hardly any movement -- should be set about 1 to 1.5* Down (at the pinion).... and a rubber suspension would be 3.5 to 4* down - because it's going to rotate up A LOT.... Urethane bushings would be "harder" and can be set at 2 to 2.5* Down etc.

So you need to know the suspension set up and adjust accordingly.

The motor is going to be 3 ish * down at the tranny ----- and the diff should be set according to the appropriate down angle (allowing for it to climb back to about zero in hard launch mode) according to how much movement it should have (a little - moderate - or a lot) -- and the working angle of the driveline will mathematically work out to about 1 ish * (the angles should cancel each other out, but they should never be 0 ----- is should always have 1 to as much as 2 degrees "difference".

So let's say the engine is down 3* -- and the driveline is down from the motor to the rear end 4* -- and the pinion is down 2*

Use this calculator to help when you're measuring



http://spicerparts.com/calculators/d...gle-calculator

[WSSix]

Originally Posted by randy

The yoke is on the same plain as the crank shaft balancer. The engine if angled up the trans yoke is angled up. All of this is being over complicated.

Get the engine or tail shaft angle
Driveshaft angle
Rear pinion angle

And then you will have all the front and rear operating angles that you need.

This is why communicating properly is important and why I wanted to make sure we all understood each other. We're saying the same thing but we're looking at it differently.

To clarify, when I say the pinion is pointed 2.5 degrees up, I mean the nose is pointed up. The gear is pointed down. Using the link/calculator Greg posted, they consider the pinion to be sloped down.

Originally Posted by GregWeld

Trey ---


One of the things that gets messed up is trying to make it too complicated....


And remember that you want the PINION angle DOWN -- because as the power is put to the rear end - it tries to rotate the pinion UPWARDS.... The type of suspension you have makes a difference in how much this is allowed to rotate from a "negative" to the positive. A race suspension which allows hardly any movement -- should be set about 1 to 1.5* Down (at the pinion).... and a rubber suspension would be 3.5 to 4* down - because it's going to rotate up A LOT.... Urethane bushings would be "harder" and can be set at 2 to 2.5* Down etc.

So you need to know the suspension set up and adjust accordingly.

The motor is going to be 3 ish * down at the tranny ----- and the diff should be set according to the appropriate down angle (allowing for it to climb back to about zero in hard launch mode) according to how much movement it should have (a little - moderate - or a lot) -- and the working angle of the driveline will mathematically work out to about 1 ish * (the angles should cancel each other out, but they should never be 0 ----- is should always have 1 to as much as 2 degrees "difference".

So let's say the engine is down 3* -- and the driveline is down from the motor to the rear end 4* -- and the pinion is down 2*

Use this calculator to help when you're measuring



http://spicerparts.com/calculators/d...gle-calculator

Thanks for the link Greg. You're correct about over complicating it. What you've just posted is what I've always thought and worked towards. Until I started having problems that is. Then, I decided to learn more and ended up where I am now.

Luckily, I have 6* of angle shims under the rear so tilting the pinion nose down won't be hard. I'm going to remove the snubber/bumper on top of the transmission too so I can lift it a little more. We'll see where I can get the angles to go to from there.

Thank you all.

[WSSix]

I went out and bought a digital angle gauge from Harbor Freight today. I verified it against a bubble level and my gravity gauge. I'm confident it's accurate within a couple tenths.

Pinion is 3 degrees nose up. Drive shaft is 1.5 degrees rear end up. Tail shaft is 3 degrees down.

Numbers are a little better I'd say but still not good enough if working angles are to be below 3 degrees.

I'm not sure why the drive shaft angle is less with the digital gauge. I put the gravity gauge right next to it and it went right back to the 3 degrees I measured the first time. I'm going with 1.5 degrees.

I'll adjust the angles in the coming days and see what happens.

Thanks

[randy]

So driveshaft and pinion is in a /\?

If so dropping the rear pinion to neg 2 degrees should lower the driveshaft to closer to zero and maybe plus or minus .5 degree. If the driveshaft does go to a neg .5 them your front operating angle would be 2.5 and if rear pinion down neg 2 degrees it would make the rear operating angle 2.5 as well. Both operating angles would be equal if thafs the case

[WSSix]

Correct. The drive shaft to pinion looks like /\.

I'm hoping to both raise the transmission and lower the pinion, but we'll see what I can come up with.

Thanks Randy

[WSSix]

I lowered the pinion last weekend to the point that it's about .5 degrees nose down now. This got the working angle at the rear u-joint down to around 1.5 degrees. I was still slightly up in the rear. This did change the front working angle but it was still a little over 3 degrees. I took the car out for a drive anyway. Nothing changed or it changed so slightly it's not worth mentioning.

Today, I tried to raise the transmission by removing the snubber on top to gain the clearance I needed. I wasn't able to go up but a few tenths due to the reverse lockout hitting the tunnel now.

So my plan at this point is to cut the tunnel out enough to get the transmission where I need it. I'll leave it open until I'm certain I have the transmission where it needs to be. Hopefully, this will either fix the issue or allow me to rule it out.

Some maybe good news is I think I'll have the clearance I need for the headers though it will get tight in places once I raise the engine. I'm also fairly certain I won't have to raise the tunnel over the driveshaft. I'll just have to change the tunnel over the transmission.

The bad news and why I'm going to leave the tunnel open until I'm certain the angles are correct is that I'm going to have to cut out part of the factory tunnel brace that's spot welded to the floor from side to side. The drive shaft will be way too close if it clears at all once I raise the transmission. This means making a DSE style trans brace and putting in new floors which I needed anyway. I'm not willing to do all of that until after I know the drive line angles are working correctly.

We'll see what happens. I'll be back with an update later.

[GregWeld]

Might not be an issue -- but if you have a rear sump -- don't get that up so much that the oil doesn't flow in to it..... ??? Maybe the pan is already sloped enough that it doesn't matter - I don't even know what motor you're running etc.