Shock/Leaf Spring Ride Height Mystery

[Msu50000]

2023 Lariat short bed

Truck rides an inch high at the right rear. Ford couldn't figure out why. Took to a frame shop for inspection and measurement, frame came back good, within spec. Took to a mechanic I have used and trust, on the lift he pointed out the left front strut was bent slightly and they thought that might be causing the issue.

Great, I want to level it anyway, so I put Bilstein 6112s (2.0 level) on the front and 5100s on the rear. Same set up as my previous F150, love how it rides, slight rake.

Problem is that the right rear is still an inch high. In fact, all measurements are off. Measurements before I installed 6112s were roughly similar ratio but i can't find the paper I had them written down on. New measurements are:

Right Front: 39 3/8
Left Front: 38 5/8
Right Rear: 41
Left Rear 40

When I measure from the top of the leaf between u-bolts to the frame on right side it's 12.5", Left side is 12".

I'm thinking this is a leaf spring or shackle but would it also cause the front to be out as well?

Any assistance or advice is greatly appreciated.

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[antho]

Maybe fuel?

 

[Msu50000]

Antho, good thought but I'm at quarter tank and haven't really noticed a difference vs full.

 

[JumboJVT]

Can't be much else other than a poochy left rear spring can it? Occam's Razor: when all other possibilites are eliminated, no matter how unlikely, whatever is left must be the answer.

Or an over-arched right spring. Can you find another truck to measure axle-frame clearance?

 

[Msu50000]

Jumbo, that's my suspicion, just wasn't sure if a leaf would cause all of the measurements to be out as far as they are? If I do go the route of replacing the leaf spring, is there a recommendation on a spring that doesn't add height but will add some payload?

 

[513Mugsy]

Last truck was a Tacoma. On the forums they all called it the taco lean. It was on account that the fuel tank , the driver and the battery are on the same side weighing down the truck, making it lean to one side. They would just place a 1/4" spacer on top of the strut assembly. That would raise the truck 1/2" because of the suspension geometry. It could be the same issue here, or something similar. How big is your fuel tank? A gallon of gas is around 8 lbs.

 

[Msu50000]

It's the 26gal tank, right now sitting about at about a quarter tank. If it were the fuel, which I haven't noticed that changing the skew much, it would probably get worse on a full tank right?

 

[513Mugsy]

In my minds eye, it should get heavier causing it to skew more. But you probably would not notice it. I know I never did on any of the last 3 Tacoma's I had. But it was there!

 

[tsigwing]

You could add a larger lift block on the shorter side, or remove the lift block from the shorter side.

Maybe add body shims and lift the bid on the short side.

 

[Porpoise Hork]

When ford brought the Ranger back to the US in 2019-2020 they installed lift blocks on the rear spring perches to raise it up about an inch over the Australian spec version. Many of us with 2019's and early 2020's noticed the same thing as OP that the passenger rear sat nearly an inch higher than the drivers rear and that the lift blocks were not the same thickness. Ford changed this mid-year and started putting the same blocks on both sides of the rear axle.

I'd check to make sure that the spring perches are properly aligned and if there are blocks that they are the same thickness.

On a side note because Ford lifted the truck but kept the same two piece drive shaft assembly that was nearly identical to the Tacoma they inadvertently introduced a slight vibration when accelerating form a start. To try and eliminate this Ford peppered the shaft with weights attempting to balance it out. The only fixes were to do what the Tacoma guys had been doing for years and shim the center bearing to change the angle of the driveshaft and u-joints or go with an aftermarket one piece shaft.

 

[PB2021]

Are both rear springs the same model/weight rating? There have been posts previously of Fords shipping with 2 seats or headlights or tail lights that didn’t match. I would think springs could be mismatched at factory much easier than a seat or head/tail light

 

[Msu50000]

I checked this and both springs are the same: ML 34-5560-Bk...I've been trying to cross reference this to a part number that I can order, but am not 100% sure which would be the corresponding part number. There are some other posts online stating that the ML 34-5560-BK is an "engineering part #" or something like that.

 

[513Mugsy]

When ford brought the Ranger back to the US in 2019-2020 they installed lift blocks on the rear spring perches to raise it up about an inch over the Australian spec version. Many of us with 2019's and early 2020's noticed the same thing as OP that the passenger rear sat nearly an inch higher than the drivers rear and that the lift blocks were not the same thickness. Ford changed this mid-year and started putting the same blocks on both sides of the rear axle.

I'd check to make sure that the spring perches are properly aligned and if there are blocks that they are the same thickness.

On a side note because Ford lifted the truck but kept the same two piece drive shaft assembly that was nearly identical to the Tacoma they inadvertently introduced a slight vibration when accelerating form a start. To try and eliminate this Ford peppered the shaft with weights attempting to balance it out. The only fixes were to do what the Tacoma guys had been doing for years and shim the center bearing to change the angle of the driveshaft and u-joints or go with an aftermarket one piece shaft.

You know now that I have thought about it some. On the Tacoma Pro coilovers, they actually lifted the spring perch on the driver's side by 1/4" to make up for this. It really is amazing what a manuf. will do to try and fix something, without actually fixing something!

 

[JQADDINGMACHINE]

You could try loosening and retightening the shackle bolts on the leaf spring with weight on it. there might be preload in it holding one side of the truck up. Just something free to try before throwing parts at it.

 

[Dakar09]

If it was fuel tank weight all of us would get this lean, and we don't. Even my 36 gallon fuel tank doesn't cause a lean when full.

Did the frame guy measure the exact position of each shackle?

I think the recommendation to loosen the shackles and tighten under weight would be a good start. If this solves it, I would assume the higher side may have been tightened without full weight on it.

It's also possible the leaning side just has a bad spring pack. They aren't metal, from what my magnetic light told me when I work under there.

Lastly, I don't believe there is any "stronger" leaf spring that won't also raise the ride height in the rear.

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