Rear Springs with Bilstein 5100's??

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John McKenzie

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Hi Guys,

Where to start? About a year ago I put on a 3/2 ready lift on my 2015 4WD King Ranch Expy but left the shocks/coil overs/UCA's etc. all stock, with the exception of the driver rear. I had a shock blow up on me not long after this install and had a friend help me install a Monroe Quick Strut just to get me by. I bought a second quick strut to have a matching set but never installed it. The stance was perfect and I got a lot of compliments after adding 17" wheels and 285/70/17 tires. However, I was having an issue with the UCA's making a clunking noise when going over small drop off's. Buddies told me I needed new UCA's, and the ones I kept going back to were the ICON's, but they are $$. I also had an issue putting $800 UCA's on a truck with stock shocks. I finally pulled the trigger on the UCA's but decided to upgrade shocks as well and went with four Bilstein 5100's.

The shop I took it to for install didn't know what they were doing and the rear was sitting a good 3" higher than the front even with the Bilsteins set at 0" (we originally left the ready lift spacers on). So I had them remove the spacers, and asked them to set the front Bilsteins at max (1") and the rears at 0". Well, I still have a TON of rake, so much so I can't even use my low beams at night. In part of the whole process, the shop mounted the shocks to the quick strut springs instead of my original springs. After over $2k in labor and the truck still not right I cut my losses and picked it up. The rear ride is so stiff its unbearable and I'm assuming it's from the springs. The front rides great at 1" and with the new UCA's, even though at 1" in hindsight I guess I didn't really need the UCA's. So here is my main question. Why am I still SO HIGH in the back with the Bilsteins set at 0", and why did the ride get so harsh? Is there that much difference in a Quick Strut spring and a factory spring? I was going to have a new shop install my factory springs in the rear, but the original shop discarded them! So now I'm looking for spring answers and also trying to find factory springs or the equivalent, especially if someone can confirm for me that the factory springs are shorter and less stiff than a quick strut spring. Also does anyone have a set of factory springs for sale?

Thanks!
 

UniqueTII

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Unfortunately I don't have an answer for you, but I just did the same change and thankfully still had the stock springs to use! I had the shop decide which springs to use and they didn't mention a height issue when the work was done.
 

Vancouver Bob

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Just a wild guess... they may have put the spring perches on upside down. The perch should slide over the ring on the shock so that the spring is sitting below the ring (towards the right). If they put the perch on the other way, the perch sits on top of the ring and puts your spring a good 2 inches or more towards the left which would preload the spring quite a bit and the back end sits way too high.

IMG_6236.JPG
 

Vancouver Bob

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A way to check is you shouldn't be able to see the spring perch extending below your shock. It should be tucked inside the bottom of the spring like in this picture.

IMG_6250.JPG
 
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John McKenzie

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Thanks for the response guys...Vancouver Bob, someone else had mentioned that to me (not on here) and I asked the shop that did it and the mechanic of course said oh there's no way I did that, etc...but it makes sense...I'm a good 2-3" too high on the rear, and the ride is super stiff...I will look when get back in to town on Thursday...currently I'm out of town in a different vehicle.

If I can confirm that they AREN'T upside down, and the issue is related more to the spring itself, do you know where I can get info on the stock spring vs. the quick strut spring I have on there now? A different shop told me they checked with ford parts and they didn't have the length or tension rating on the factory springs?! I find that hard to believe, but haven't called myself...on the Monroe quick strut, I didn't see any data on their website for just the spring...I'm just curious how the spring length and "tension" (if that's the right term) compares between the two.

Finally, if I determine the springs on there aren't gonna work, and decide I want the ride etc. of the factory spring, any ideas on the best place to get factory springs without having to buy the whole assembly?

Thanks again for the responses.
 
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John McKenzie

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I forgot I had a pic on my phone. I think this is the driver side rear. My perches look a little different than yours. Does this look right?

upload_2020-8-4_21-25-3.jpeg
 

Vancouver Bob

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I forgot I had a pic on my phone. I think this is the driver side rear. My perches look a little different than yours. Does this look right?

View attachment 37501

Yes, that's correct. So perches aren't the problem.

I can't remember where I got my springs but I just got the ones that were for my vehicle. I don't have a clue on the actual spring specs. I will say the new springs I got looked physically different. The new springs were a bit smaller in gauge but there were more coils, if that makes sense.
 
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Vancouver Bob

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I'm pretty sure I got ACDelco Springs off RockAuto. I checked their site and they list the spring specs.

They also have the Monroe Quick Struts and list dimensional specs for the assembly, but no spring ratings or anything.
 

Sunflowergirl

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I forgot I had a pic on my phone. I think this is the driver side rear. My perches look a little different than yours. Does this look right?

View attachment 37501
Sounds like you got f150 5100s bc on stock setting on an expedition those would give you almost 2” if lift due to different spring rates. Did you order expedition or f150 5100s?
 
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