Knuckle Alignment Tool - Why 3mm?

[60Works]

Why 3mm?

When marking the center lines of the axle housing and the spindle onto the SST 09634-60013 why are they not closer?

Why is the formula: E = D - 3mm?

Is it because the brim of the hat of the bearing cap simulator is 3 mm? No, it is not.


Or is it because the bolt will not allow the scribing pointer to meet in the true center of the trunion rotating axis? (edit) Yes, it is.

3 mm = sin tan(trunion angle) * .5(bolt diameter)

 

[NeverGiveUpYota]

Got you going on this eh, G? Same sheet is in front of me and I've scribbled notes on it from @OTRAMM's video. I have no words to say, way more novice than you. Maybe @mwebfj60 can add in his thoughts.

 

[NeverGiveUpYota]

Are you talking this as the brim of the hat? That’s way more than 3mm or would seem so by eye... nothing on hand to measure accurately in the house right now.

Found a little ruler. Snap-On of all brands too. Never noticed before.

 

[60Works]

Yes, Yota. That's what I'm calling the 'brim'.

The reason this is important is (to me at least) is that there is some variation in the SST's offered by various vendors. The 'brim' dimension varies and some have reported that it doesn't matter at all. I want to know exactly why it matters or not.

Steering knuckle centering tool instructions (FAQ)

If the brim matters, the tool I ordered is way off. This can be compensated for by inserting the actual tool dimension into the equation.

If the bolt diameter matters, we need to find out the actual bolt diameter in the Toyota tool and compare it to the tools we are using. This too can be compensated for by calculating the sin tan dimension.

 

[NeverGiveUpYota]

Is the 3mm the spacer that was removed?

 

[Prairie Swamp]

Or is it because the bolt will not allow the scribing pointer to meet in the true center of the trunion rotating axis?

3 mm = sin(trunion angle) * .5(bolt diameter)

I would say you would use the full diameter (17mm). Because the scriber comes in from both sides. The scriber falls short 1/2 D from the inside and 1/2 D from the outside?

Anyone know what the camber angle is. tan (theta) = 3mm/17mm. atn (3/17) = 10.00798 degrees or close enough to 10 degrees.

 

[60Works]

I would say you would use the full diameter (17mm). Because the scriber comes in from both sides. The scriber falls short 1/2 D from the inside and 1/2 D from the outside?

Anyone know what the camber angle is. tan (theta) = 3mm/17mm. atn (3/17) = 10.00798 degrees or close enough to 10 degrees.

The scriber comes in from both sides but each side meets in the middle.

Duh. Got it now.

And you're right about tan instead of sin too.

 

[60Works]

Here is a picture pulled from this thread by Tokamak:

Home Built Knuckle Centering Tool

He shows the trunion camber at 10.50°. Could anyone else please verify that number?

 

[mwebfj60]

The A2 measurement shown above should be the same as the height of the similar looking pieces on the knuckle cap and steering arm. Mine were .0008” different between tool and parts.

Edit...The reason you need to measure from the bottom of the flanges and not from cutout to cutout as shown in the FSM pic is if you look closely at the tool, there is a step down between the tool’s flange (collar) and the cutout.

As far as the alignment below dead center, I’m curious as well.

 

[nogo]

If you look closely at the tool, there is a step down between the tool’s flange (collar) and the cutout.

Are you referring to the area outlined in green as the 'step-down'?

 

[mwebfj60]

Yes

 

[mwebfj60]

The thickness of the collar/brim/flange doesn’t matter. There aren’t any measurements that take it into consideration.