Wheel Alignment question for smart people

[MudRunnerTD]

Ok, trying to do a Cowboy front wheel alignment. Yes yes, I could go somewhere but close enough will do gents.

Ok, on the hoist and measuring tread block to tread block. Front and back of a 37 Trep.

Measurements are

Front 1406mm
Rear is 1409mm
Diameter at tread block is 818mm

Now I think standard Front end alignment is like 2 degrees Toe In.

The above are a very slight Toe In. I don't want to scrubb out the tyres but keen to get somewhere near factory if i can.

Any Mathematicians out the can tell me what the measurements should be to be close to 2degrees Toe In.

Can someone also confirm I'm chasing 2 Degrees Toe In

Thanks Gents.

Anyone with Kids doing Year 12 Maths this will be a cake walk for them. Lol

[PeeBee]

asin3/818=0.210deg

But you are running highly unroadworthy tyres and could kill thousands of young kiddies and albatrosses with such an aggressive tyre and big beard. Buy a really big mirror and have a look at what you are doing. I like marmalade curry as well

[Plasnart]

Ok mate this is what I worked out. If you look at your wheel from above and turn it 360 degrees with a pen taped to the tread, you'll draw a circle on the floor. This circle will have a diameter of 818mm. You want to work out the length of that circumference for a 2 degree turn. So the circumference of a circle formula is 2 x pi x radius. So your circle is 2 x pi x 414 = 2601.24mm in length. So for every 1 degree slice of that pie, the circumference is 2601.24/360 = 7.23mm. Therefore for a 2 degree toe in, 7.23mm x 2 = 14.46mm. This sounds like wayyyy too much toe in mate, unless I've completely stuffed up the calculation!

[nissannewby]

The spec is a measurement Daz. It's -2mm to 0mm. This equates to anything from 0-9°.

You also need to be doing the measurement witht the vehicle on the ground. As it will be different on the hoist with the suspension at full droop.

[MudRunnerTD]

Ok mate this is what I worked out. If you look at your wheel from above and turn it 360 degrees with a pen taped to the tread, you'll draw a circle on the floor. This circle will have a diameter of 818mm. You want to work out the length of that circumference for a 2 degree turn. So the circumference of a circle formula is 2 x pi x radius. So your circle is 2 x pi x 414 = 2601.24mm in length. So for every 1 degree slice of that pie, the circumference is 2601.24/360 = 7.23mm. Therefore for a 2 degree toe in, 7.23mm x 2 = 14.46mm. This sounds like wayyyy too much toe in mate, unless I've completely stuffed up the calculation!

You scare me... but you are right!!!! Way too much

[MudRunnerTD]

The spec is a measurement Daz. It's -2mm to 0mm. This equates to anything from 0-9°.

You also need to be doing the measurement witht the vehicle on the ground. As it will be different on the hoist with the suspension at full droop.

But?? It's the GQ. Suspension will have nothing to do with surely??? A solid front Axle has a controlled fixed length?

But another note though, so my 3mm is plenty? Too much even? It's 1.5mm per side?

[nissannewby]

But?? It's the GQ. Suspension will have nothing to do with surely??? A solid front Axle has a controlled fixed length?

But another note though, so my 3mm is plenty? Too much even? It's 1.5mm per side?

You still have castor. So the position of the tyres sitting at ride height will be different when the suspension is drooped. If castor didn't exist then you would be fine.

But yes you are close. You could work back from those measurements. 0.1mm is equal to approximately 0.45°. So if you have -3mm toe then you are at around 13.5°.

[Plasnart]

You still have castor. So the position of the tyres sitting at ride height will be different when the suspension is drooped. If castor didn't exist then you would be fine.

But yes you are close. You could work back from those measurements. 0.1mm is equal to approximately 0.45°. So if you have -3mm toe then you are at around 13.5°.

I have absolutely no comprehension of these figures Matt, 13.5 degrees of what equals 3mm?

But this is not my thread so ignore if I am an ignoramus.

[nissannewby]

I have absolutely no comprehension of these figures Matt, 13.5 degrees of what equals 3mm?

But this is not my thread so ignore if I am an ignoramus.

Just backwards working the numbers. The spec says -2mm to 0mm for the toe. It also states that this is 0-9°. So if 0mm is 0° the -2mm is 9°. Then I just divide that into 20 points so 1 point is 0.1mm. Which equals 0.45°. Darren is at -3mm with his toe adjustment. So 1mm equals 10 points or 4.5° on top of the 9° at -2mm toe.

[MudRunnerTD]

Just backwards working the numbers. The spec says -2mm to 0mm for the toe. It also states that this is 0-9°. So if 0mm is 0° the -2mm is 9°. Then I just divide that into 20 points so 1 point is 0.1mm. Which equals 0.45°. Darren is at -3mm with his toe adjustment. So 1mm equals 10 points or 4.5° on top of the 9° at -2mm toe.

Thanks mate, that's what I was looking for. I will drop it on the ground and try and get it to 2mm. Measuring off treads alone with a tape measure there is almost certainly 1mm in it.

[nissannewby]

Thanks mate, that's what I was looking for. I will drop it on the ground and try and get it to 2mm. Measuring off treads alone with a tape measure there is almost certainly 1mm in it.

If you know the thread pitch of you tie rod ends then this is quite easy. For example if the tie rod ends have a 1mm pitch then 1/2 a turn would equal approximately 1mm off your measurement. Remembering you have 2 tie rod ends so the 1/2 turn is 0.5mm for each end or 1mm in total.

[nissannewby]

Do you have a laser distance finder/measuring device? Possibly at work.

[MudRunnerTD]

Do you have a laser distance finder/measuring device? Possibly at work.

Hahahaha Every working day of my life for the last 20 years i have had one in my hand. That will make the job way way easier. Im a goose! Thanks legend.

[Brissieboy]

Having a little trouble with some of the figures mentioned in this thread.
If the tyre diameter is 818mm and the width is at the front of the tyre is 1406mm and at the rear is 1409mm (that's how I interpret the OP's figures):
The 'toe-in' on each tyre (assuming equal on each) will be (1409-1406)/2 or 1.5mm.
Using basic trigonometry, the sine of the angle of the 'toe-in' is 1.5/818 (opposite over hypotenuse) = 0.0018337408312958.
Using inverse sine this equates to an angle of about 0.105degrees.
Does that make sense or have I got it all wrong?

[MudRunnerTD]

Having a little trouble with some of the figures mentioned in this thread.
If the tyre diameter is 818mm and the width is at the front of the tyre is 1406mm and at the rear is 1409mm (that's how I interpret the OP's figures):
The 'toe-in' on each tyre (assuming equal on each) will be (1409-1406)/2 or 1.5mm.
Using basic trigonometry, the sine of the angle of the 'toe-in' is 1.5/818 (opposite over hypotenuse) = 0.0018337408312958.
Using inverse sine this equates to an angle of about 0.105degrees.
Does that make sense or have I got it all wrong?

Thank you. Trig was not my thing 35 years ago and still isn't. Lol. You are probably very right, Plasma and Peebee are also bang on.

My memory was 2 degrees but it seems outrageous. Maybe I remember 0.2 degrees whoch makes way more sense.

Thanks everyone.

[billyj]

if were talking a soild axle then just set it to 0 toe and it will be fine