Xterra Alignment Woes

1990C4S · 03-05-2023, 05:49 AM

My 2015 Xterra is driving me crazy...

Last week I noticed a broken rear leaf spring. I had the springs replaced at a local spring shop, and now my 'alignment' is out. The steering wheel was 'dead straight' before, now it about 30 degrees out to drive straight.

I took the car for alignment, and the technician said the front is not the problem, it's the rear thrust angle.

Looking at the numbers the left rear toe is -0.24 degrees, and the right rear toe is +0.34 degrees.

So the rear axle is not perpendicular to the vehicle now. Measuring center to center front to rear wheels, the passenger side is 0.25" shorter than the driver's side.

How to fix? There is zero adjustment, the axle sits on pins that go into the leaf springs, and the shackles are welded to the frame.

I can try unclamping, the pulling the passenger side back, driver's side forward, and then reclamping.

Or I do I have to make an intermediate plate with offset pins, to get 1/8" on each side?

I don't blame the spring guy, I don't see how he can fix the problem, unless the springs are out of spec? Or one is backwards?

I've had old cars that weren't aligned, and I drove them for years, but this is my wife's car she won't drive it 'as is'.

Scott Douglas · Scott Douglas's Garage

I'd take it back to the spring shop and explain it just as you did here. The springs aren't made correctly and they need to make it right.

1990C4S · 03-05-2023, 06:13 AM

I'm going to try that, I'm not optimistic.

It's a crap design. That's the real problem.

Scott Douglas · Scott Douglas's Garage

I'd take measurements from the center line of the front shackle to the pin location on each side, just to see if that is in fact where the problem lies.

masraum · 03-05-2023, 06:20 AM

I wonder if the problem is with the springs or the installation. Maybe the springs intentionally have the hole for the pin shifted one direction or the other, and they have one side installed backwards.

kach22i · kach22i's Garage

Quote:

Originally Posted by masraum

I wonder if the problem is with the springs or the installation. Maybe the springs intentionally have the hole for the pin shifted one direction or the other, and they have one side installed backwards.

I agree, and that is the best theory so far.

1990C4S · 03-05-2023, 07:55 AM

Quote:

Originally Posted by masraum

I wonder if the problem is with the springs or the installation. Maybe the springs intentionally have the hole for the pin shifted one direction or the other, and they have one side installed backwards.

Pain in the ass to do, but I'm going to check tomorrow AM,

john70t · 03-05-2023, 08:10 AM

There is lifted, lowered, hopping, nose down, nose up stances.
Show'em all your crabbing style rolling down that freeway sideways playa.

1990C4S · 03-06-2023, 05:24 AM

The spring shop is going to double check the install, he is very confident that the springs are correct.

The more I think about this, the more I think that the car was driving straight with a really bad rear axle thrust angle. I fixed that problem (it's close, but not perfect), and now the car pulls to one side, so the car was adjusted to accommodate the bad rear axle. When the axle was fixed, the correction in the front became wrong.

It's possible my only problem is that the front toe is incorrect relative to the steering wheel. I suspect all the green numbers from the alignment shop were done with the steering wheel off-center.

If the spring guy says the rear is correct, I'm going to adjust the front toe on both sides equally to make the car steer straight.

asphaltgambler · 03-06-2023, 07:28 AM

But in your OP the thrust angle was way off. So assuming the center pinch bolt for the spring pack is offset from dead center; spring eye-to-eye, one spring is installed backwards which is easy to do. If the pinch bolt is designed to be centered, then one of two springs was manufactured incorrectly. Lastly if the protruding stud end is smaller diameter than the original, it would not fit snugly in the spring perch hole, allowing the rear axle to shift

1990C4S · 03-07-2023, 09:44 AM

Quote:

Originally Posted by asphaltgambler

But in your OP the thrust angle was way off. So assuming the center pinch bolt for the spring pack is offset from dead center; spring eye-to-eye, one spring is installed backwards which is easy to do. If the pinch bolt is designed to be centered, then one of two springs was manufactured incorrectly. Lastly if the protruding stud end is smaller diameter than the original, it would not fit snugly in the spring perch hole, allowing the rear axle to shift

I had it checked at the spring shop, he says he's done hundreds of 'trucks' similar to mine and never had any steering issues. He confirmed the springs are with 1/16", not perfect, but I can live with that.

I don't think the numbers I posted are 'way out', but they are out.

After more thought, I think it's all in the front. The rear thrust problem might make it crab-walk, but I don't think it can cause my issue.

The car has gone back to a better alignment shop, where the front can be inspected again.

john70t · 10:11 AM

Ensure surface level and check tire to fender arch to see if a quarter section has dropped.
Also check tire to front wheel well front and back.

Screw together some scrap 2ft 2x4 solid in all three axis.
Use that to measure hub-to hub. Hub-to-frame. Frame square. Spring points to each other and front points

The Model T was built with hand tools and a lot of measurements.
Something is off somewhere.

masraum · 03-07-2023, 10:16 AM

You are essentially in a "drift" all of the time now. That's why your wheel is 30º off. You said that it was NOT like that before the springs were swapped, right?

If the wheel was straight before the spring swap and is now not straight, and the ONLY thing that was done to the vehicle was the spring swap, then I've got to think that this MUST be related to the springs. I'm super curious to hear the outcome/fix.

Jeff Hail · 02:11 PM

Have the shop swap the leaf stacks side to side and see what happens.

Dodge Rams with rear leafs have to be porta-powered on one side to push (sway) the centerline during wheel alignments to get the ass end correct. Even brand new trucks are found to be off considerably.

Ford trucks are a lost cause on rear thrust as the axle housings tend to have toe issues also.

Any thrust line over 0.20 will cause a drift that can be felt or will cause the steering wheel to creep and require steering corrections as the rear drifts while moving in forward motion.

Has this vehicle been damaged? How did the leaf stack break? Accident? Impact to the rear bumper reinforcement or mounting? Off roading? Has the wheelbase been confirmed to be correct on each side after the rear leafs were replaced? Rear wheels checked for damaged? Leaf stack center pins still present and have not been bent or sheared off? If all check out proceed to swapping the leaf stacks side to side.

After swapping the leaf stacks if the problem changes (alignment values reverse) sides you can shift the axle housing with a porta-power. Loosen up the U Bolts so the perch plates with the center pins are free. Jack the housing by pushing one side back and tighten everything up. It only needs to move 0.30 on the negative side . The opposite side will follow it in steer. You will end up with something like +0.04 each side. Not perfect but will drive good and stable. If you do this yourself and do not have access to a porta-power a come along can usually manage it. Expect some spring back once everythings is under pressure.

Wheel alignments start at the rear. The centerline begins at the rear whether angles and values are adjustable or fixed. Once the rear is squared away any adjustments to the front takes place.

When the alignment is correct, steering wheel straight ahead set complete you will then need to have the steering angle sensor calibrated (zero point set) so your ABS and Traction control function properly. The yaw sensor is reliant on an accurate centerline when moving away from a straight line.

1990C4S · 03-08-2023, 12:20 PM

The vehicle has never been in an accident, owned since new.

My wife took it to a 'better' alignment shop, their early diagnosis lines up with what Jeff said above about ABS and YAW.

I'm traveling for work, we're throwing money at this problem to fix it.

masraum · 03-08-2023, 12:27 PM

Quote:

Originally Posted by 1990C4S

we're throwing money at this problem to fix it.

That's always a lot of fun for folks like us. I'm sure you'd agree that this is the best/preferred way to handle this sort of thing!

When I was a teen my dad was away for work and I had an issue with the tranny in my car. The shop that we took the car to was known to do good work, but saw me and my mom and screwed us over. Dad was grumpy when we got back, but knew that what was done was done.

1990C4S · 03-09-2023, 06:01 AM

I'm cheap, and I will drive anything.

My wife won't drive anything that has the slightest 'defect', say a steering wheel that's off by 20 degrees.

Anyhow, I'm working 1,500 miles from home for the next little while. I can't fix it from here. It needs a clutch, and the steering repair will look small on that bill.

kach22i · kach22i's Garage

Quote:

Originally Posted by Jeff Hail

Wheel alignments start at the rear. The centerline begins at the rear whether angles and values are adjustable or fixed. Once the rear is squared away any adjustments to the front takes place.

Good to know, such a deep well of knowledge in this forum.

1990C4S · 03-15-2023, 10:16 AM

The car is fixed. I don't think they touched the rear, the front was adjusted, the Traction light is off, and the car steers straight.

I'm not home to drive it, or to ask the mechanics what he did. But it's fixed.

Scott Douglas · Scott Douglas's Garage

Congrats!
It'll be interesting to find out if the car actually goes down the road correctly or if it crabs at all. Let us know when you get home and have a chance to follow your wife to see if it does or not.