Both Front Tires Inside Wear

[atkinson40]

72 620.  Stock front end.   Both Front tires are wearing on the inside.  I took it to get aligned and was quoted $200 without them looking at it. 

 

What could be causing this?  Maybe I could align it?

 

Thanks Kevin

[iceman510]

not sure what all is adjustable on a '72 620, but most likely you have a toe-out condition.  Does it want to wander on the freeway or at highway speeds?  Does it follow ruts (if you have such in San Diego) or the rain grooves on the road?

 

You could align it, but to do it accurately takes a good level surface, tools for the job or patience, jackstands, string and an accurate tape measure.

 

https://www.motortrend.com/how-to/ctrp-1204-determining-wheel-alignment-string-your-car?galleryimageid=c8550ee7-b6d4-484f-b432-32cd1b631406

 

I use toe plates for some minor front adjustments (don't really square the car though), but will need to do the full thing next spring on my race car.

[datzenmike]

If you turned the torsion bars up for more clearance this will introduce toe in and negative camber the tilting of the tire tops towards the vehicle forcing the vehicle weight to ride more on the inside tread. Worn king pins can also accelerate tire wear.

 

To quickly check toe, drive ahead onto a flat level surface, get out and look at a front wheel. Line up the front and rear sides of the tire with the rear tire. You'll have to adjust the steering wheel. Once front and rear wheels are in alignment on one side go to the other and look. If you look across the two bulges of the front tire and can't see the rear tire then the truck is toed in. If you can see the tread on the rear tire it's toed out. If you can't tell it's probably close enough. If it looks out it is.

 

Camber can be adjusted by setting the truck back to stock ride height.    

 

 

[banzai510(hainz)]

where you go Les Swab cam look at it. Maybe its been ahile sincew I had any work done on my car. Least they can line it up best they can.

I will assume you have toe out issues.  My yellow 510 I just looked at the driver side wheel from front and lined the up straight as you think. then go to passenger side and see what the wheel is doing..

 

the tire shop will say we got to puit all new parts in there.  Just have them line it up

 

put you could ck for loose ball joints or Kingpins before you take it there. I had a wore out tierod end also. so be good to see if its tight first before taking it there and just say do a alighment. If thats the price now.

 

I did mine myself with a tape measure.

[Stoffregen Motorsports]

Tape measure and two pieces of steel channel about 40" long is how I check toe. You could do it with two builders levels. And to check it by yourself, use a bungee cord to hold one of the levels, or steel or whatever onto the tires. Just make sure you have a straight shot from  one side to the other, meaning, no exhaust or other parts in the way of the tape measure.

 

Ideally, you'd have a tiny bit of toe in, like 1/16" to 1/8". Larger diameter tires can use more toe in.

[atkinson40]

28 minutes ago, iceman510 said:

not sure what all is adjustable on a '72 620, but most likely you have a toe-out condition.  Does it want to wander on the freeway or at highway speeds?  Does it follow ruts (if you have such in San Diego) or the rain grooves on the road?

 

You could align it, but to do it accurately takes a good level surface, tools for the job or patience, jackstands, string and an accurate tape measure.

 

https://www.motortrend.com/how-to/ctrp-1204-determining-wheel-alignment-string-your-car?galleryimageid=c8550ee7-b6d4-484f-b432-32cd1b631406

 

I use toe plates for some minor front adjustments (don't really square the car though), but will need to do the full thing next spring on my race car.

 

Thanks iceman510, 

 

I don't remember it wandering or following ruts.   I will pay attention. 

I only drive it maybe 1K a year for occasional building material trips.

[atkinson40]

25 minutes ago, datzenmike said:

If you turned the torsion bars up for more clearance this will introduce toe in and negative camber the tilting of the tire tops towards the vehicle forcing the vehicle weight to ride more on the inside tread. Worn king pins can also accelerate tire wear.

 

To quickly check toe, drive ahead onto a flat level surface, get out and look at a front wheel. Line up the front and rear sides of the tire with the rear tire. You'll have to adjust the steering wheel. Once front and rear wheels are in alignment on one side go to the other and look. If you look across the two bulges of the front tire and can't see the rear tire then the truck is toed in. If you can see the tread on the rear tire it's toed out. If you can't tell it's probably close enough. If it looks out it is.

 

Camber can be adjusted by setting the truck back to stock ride height.    

 

 

Thanks datzenmike,

 

I have not adjusted the torsion bars. I've had it for 10-12 years.  I'll check toe per your directions.  And check the ride height.

[banzai510(hainz)]

well how many miles you get out of these tires????

 If you just have bad camber tires will still last at least 15k miles. But if camber bad  and toe IN or OUT they will not last long at all.

 

but remember ck the tie rods for looseness . Mine were actually wobbling!!!!!!!! if 1/8inch loose youll never set it up right.

Edited November 30, 2022 by banzai510(hainz)

[atkinson40]

On 11/30/2022 at 10:24 AM, datzenmike said:

If you turned the torsion bars up for more clearance this will introduce toe in and negative camber the tilting of the tire tops towards the vehicle forcing the vehicle weight to ride more on the inside tread. Worn king pins can also accelerate tire wear.

 

To quickly check toe, drive ahead onto a flat level surface, get out and look at a front wheel. Line up the front and rear sides of the tire with the rear tire. You'll have to adjust the steering wheel. Once front and rear wheels are in alignment on one side go to the other and look. If you look across the two bulges of the front tire and can't see the rear tire then the truck is toed in. If you can see the tread on the rear tire it's toed out. If you can't tell it's probably close enough. If it looks out it is.

 

Camber can be adjusted by setting the truck back to stock ride height.    

 

 

 

I put the truck on a flat surface and lined the driver's side wheel up with the back wheel.  The driver's side wheel is pointed straight forward.

 

The passenger side front wheel is not pointed straight forward.  It points out.  Noticeably.  I think this is wrong.

 

Could this cause inside tire wear?

[datzenmike]

They should be almost totally parallel. In fact just slightly toed inwards 0.025".

 

Make sure vehicle is at the vehicle height you want because if you raise or lower later it will need aligning all over again.

 

The steering cross rod runs under the front underside of oil pan. Each end is threaded, one left hand the other right hand and each has a rod socket screwed on and a lock nut. Loosen both lock nuts several turns. You may need vice grips, but if you put your hands on top and around the cross rod and turn it towards you the toe in is increased. Try a full turn. Now bounce the front suspension to equalize the tires. Now adjust the front wheel to align with the rear one and check the other side. If it was toed out before you probably saw some the the tread on the rear tire. Now there should be much less tread to see. Keep adjusting and checking till you can't see any difference between either sides. This is more than close enough to drive to an alignment shop or you can do it yourself....

 

Two 5' lengths of thin strong cord.

Flat ground or lawn.

Four stakes driven very securely into the ground.

The string must be very taught, the two lines absolutely parallel to each other, as high as the center of the wheels (about 13") and far enough apart to drive the front wheels between.

 

Drive between the parallel strings

Measure from the string to the rear edge of the rim and record this. Then to the other side and record

Now measure from the string into the front edge of the rim and record. Then to the other side.

 

Add the two rear measurements together and then the two front measurements.

If the rear measurements are smaller than the front then the car it toed out

If the rear measurements are larger than the front ones the car is toed in.

 

When the front measurements are 1/4" or 0.025" less than the two rear measurements you are toed in by 1/4". The acceptable limits are 0.20"-0.28" so 0.25 is fine

 

Car has to be sitting on it's wheels, and don't forget to bounce the suspension after every adjustment. When done, do NOT forget to tighten the two lock nuts!!!!

 

 

 

 

[Stoffregen Motorsports]

Yes, measure the toe at ride height. Something I saw earlier in the thread suggested to me that maybe you were going to try and adjust it while on jack stands. This will not work.

 

Two pieces of metal, a bungee cord and a tape measure is all I use.

[Stoffregen Motorsports]

This guy does it with duct tape -

 

[datzenmike]

Interesting. Close enough to go to the shop with. Tires are not symmetrical enough, they are full of bumps and irregularities and lettering. Might work on a truck but hard to run a tape measure that high up at either the front or rear of the tire or both. On mine the exhaust and transmission are in the way and why I measure to the rims. 

[Stoffregen Motorsports]

I mentioned that earlier. You have to have a clear shot underneath from side to side.

 

Yes, you need to pick a spot on the tire to put the steel. If you're on a letter on one side of the tire, it needs to be on the same bump on the other side of the tire.

[banzai510(hainz)]

19 hours ago, atkinson40 said:

The driver's side wheel is pointed straight forward.

 

The passenger side front wheel is not pointed straight forward.  It points out.  Noticeably.  I think this is wrong.

 

Could this cause inside tire wear?

YES!!!!!!!!!!!!!!!!!!!!!!!!!

[atkinson40]

I set the Toe. 

 

Then in trying to measure camber, I put a builders level straight up and down across the middle of the tire.  I needed to pull the level out at the top about an inch to get the bubble to indicate a straight up and down line.

 

Is this an OK method of checking camber? 

 

What do I do to fix it?

[datzenmike]

Again I don't think a tire sidewall is uniform enough. I would use the 12 and 6 o'clock positions on the rim, with spacers.

 

Camber is 1⁰ 15' on a 14" diameter rim. By my figures the top of the 14" rim will be tilted inwards by 0.152" compared to a vertical line up from the bottom edge of the rim.

 

The specs say +or- 1⁰ so basically perfectly vertical will be ok as well.

[Stoffregen Motorsports]

3 hours ago, atkinson40 said:

I set the Toe. 

 

Then in trying to measure camber, I put a builders level straight up and down across the middle of the tire.  I needed to pull the level out at the top about an inch to get the bubble to indicate a straight up and down line.

 

Is this an OK method of checking camber? 

 

What do I do to fix it?

Depends on the length of the level. One inch on a 48" level would be different than one inch on a 60" level.

 

Mike - you can get close enough to be able to drive it without bringing it to the alignment shop.

[datzenmike]

Absolutely. I've set my toe and camber myself and have never paid to do what I can do myself. I took the front wheel off and set the car down on the LCA at the same height as if the tire was on. Put a magnetic torpedo level vertically on the rotor. Got it to vertical... close enough.

[paradime]

12 minutes ago, datzenmike said:

Absolutely. I've set my toe and camber myself and have never paid to do what I can do myself. I took the front wheel off and set the car down on the LCA at the same height as if the tire was on. Put a magnetic torpedo level vertically on the rotor. Got it to vertical... close enough.

 

There's less leverage exerted on the suspension with the vehicle sitting further in on the LCA and not the tires further out. Wouldn't the suspension sit in a higher position because of that? I usually place a torpedo level just inside the tire lip on the outer edge of the rim with the vehicle sitting on the ground just to get it in the ball park. 

[datzenmike]

I made sure the spindle or axle was at the same height from the ground with tire off as with tire on. Weather supported on a block of wood or on a tire, the camber displayed would be the same don't you think?

[atkinson40]

I was having a difficult time figuring out a spacer, straightedge,level and tape measure arrangement for camber, so I tried the following.

 

I hung a plumb bob off the fender lined up with the spindle and measured the distance from rim to plumb bob line at the top and bottom of the rim.

 

My top of the rim measurement was 1/2 inch greater than the bottom of the rim measurement. 

 

I have 16 inch rims.

 

is this a fair method to measure camber?

[atkinson40]

54 minutes ago, atkinson40 said:

I was having a difficult time figuring out a spacer, straightedge,level and tape measure arrangement for camber, so I tried the following.

 

I hung a plumb bob off the fender lined up with the spindle and measured the distance from rim to plumb bob line at the top and bottom of the rim.

 

My top of the rim measurement was 1/2 inch greater than the bottom of the rim measurement. 

 

I have 16 inch rims.

 

is this a fair method to measure camber?

 

My bad.  The rims are 14" given the tire size on them.

[datzenmike]

Yes it's very good way to measure the camber angle.

 

0.5" at the top on a 14" diameter rim is a 2.0454 degree (or 2⁰ 2' 43") negative camber. Generally a very slight negative camber is preferred for proper handling. 

 

The '73 620 camber angle is 1 degree 15' or 1.25 degrees so you are a little too negative by just over 3/4 of a degree putting more weight on the inside edge of the tire. This is an advantage for handling on turns but accelerates tire wear the more negative you go. Datsun recommends 1.25 degrees as a good compromise.

[atkinson40]

My rim's diameter measure 15.75 inches, but the tires are 14's.  

 

I'm confused?