Moog / OEM coil spring mismatch?

[maidez]

Today I spent a very frustrating day trying to compress Moog coil springs on my new KYB struts. I had taken out one of O'Reilly Auto's MacPherson strut spring compressor, and went through several failed attempts of trying to 'grab' the right number of coils with the compressor so that I could re-attach the coil seat, and subsequently extricate the spring compressor. Either the compressed spring was too long to fasten the seat, or there was insufficient clearance to remove the jaws of the compressor from between the coils. I had done my rears several months ago, so sorta, kinda thought I knew what I was doing.

When I finally gave up, and decided I would just bring the struts and springs to a tire/suspension shop and let them assemble everything, I decided to check the old spring against the new. I usually compare old and new parts first thing, but skipped this step because I apparently haven't suffered enough in my recent past. The Moog coil springs I purchased (Moog part 81132) are roughly the same length, but there are two more spring 'winds' over this length. These extra turns result in a much tighter spacing which is probably why I had so much more trouble with the fronts. I checked on Rock Auto's and Moog's website to confirm that part #81132 is correct for my 2002 V6 Explorer XLT front struts.

Now I'm not sure if I should proceed with my plan of having a suspension shop compress these springs. Has anyone seen Moog springs that appear to be significantly different than the OEM ones in this manner? Any idea if I would experience noticeable suspension/ride problems if I used these ones? I suspect that if Moog did this on purpose, it would be to firm up the ride; I'm OK with that, but just want to make sure this is an intentional change before I reassemble everything.

 

[Ronin8002]

Interesting you bring this up because I'm getting ready to do the same exact thing on a set of Monroe Reflex struts.

I do know that when I go to fordparts.com and look under my year/model for coil springs there are about 5 or 6 options of oem coil springs. I am assuming they either underwent some changes or they put different springs in the front depending on V-6/V-8 4WD/2WD/AWD etc. Perhaps the moogs are modeled after whatever variant you don't have in your truck currently?

Also, is the spring compressor you rented the red, double jaw type that compresses both sides and top/bottom of the spring simultaneously?

 

[Ronin8002]

I don't have my springs in front of me to check, but if the diameter of the wire used to make the spring is smaller and there are more coils over the same length of spring, that should lower the spring rate, which should give a softer ride.

 

[Ronin8002]

another interesting thing is the moog part number I ordered was 81130 for my 2004 E.B. 4x4 v-6.

 

[maidez]

Thanks for the ideas; I've followed up on all of them, but I'm afraid I'm no closer to an explanation.

The Moog catalog lists part 81132 for all 3 engines available on a 2002 Explorer, and neither they nor Rock Auto have distinguish between 2WD and 4WD for this item.

I've put a caliper on the OEM and replacement springs, and the Moog ones might be a tiny bit smaller (fractions of a mm) it's too small to really register as a difference on my caliper. I notice it as a tiny bit more resistance when moving the caliper from the Moog coil to the OEM one. This feels more like manufacturing tolerances, or surface coating differences to me.

The strut compressor I used looks like this: The hooks fit between the coil springs, and when the spring is compressed enough on the strut, there just isn't enough clearance for the lip to allow the tool to be removed.

The Moog catalog does show that the 81132 is correct for 2002, and 81130 for 2004, so that observation is expected.

Oddly enough when I took a closer look at the outside of the box (who reads coil spring boxes?), there is a blurb that visual differences are expected between the original and replacement springs. The example that is given is the replacement springs being shorter because the originals 'sagged'. It refers to the application catalog as the final arbiter. It doesn't describe the extra coils that I'm seeing, and instead describes length discrepancies, but maybe I'm OK?

 

[Ronin8002]

I suspect the slight wire diameter difference is due to the surface coating...the OEMs on mine have a plasti-dip sort of coating and the moogs have something thinner...apparently its powdercoating with maybe a thin urethane layer over it.

If your local shop has one of those wall mounted spring compressors they might have some tricks for dealing with the issues you're having.

Since Moog is adamant that this is the right spring you're probably OK as long as the coils don't bind (touch) when the assembled strut is compressed under load (installed on the vehicle)

 

[Ronin8002]

Any updates? I attempted to do my front springs with a "clamshell" style macpherson strut compressor and I ran into the exact same problems as you did.

I'm going to have to take them to a shop. The rears are going to be much easier I think since the spring seat is much lower on them so the coil spring doesn't have to be compressed so much.

 

[maidez]

Any updates? I attempted to do my front springs with a "clamshell" style macpherson strut compressor and I ran into the exact same problems as you did.

I'm going to have to take them to a shop.

I did bring them to a local tire/suspension shop, and they were able to compress and assemble them no problem. The front counter person implied that I was completely crazy to try this on my own, I let him know that I understand the energy stored in a compressed spring of this size, and was using the tool with appropriate caution.

I'm in the middle of a complete front suspension overhaul in my 'spare' time, so I can report that the struts were assembled and visually look OK, I haven't yet reinstalled them, and can't comment on the ride characteristics.

 

[Ronin8002]

Mine are on the truck now and no apparent problems. I did get about 3/4"of lift from them.

 

[Ronin8002]

After driving around for a few weeks, I think now the springs have settled to their normal installed height. Lost about a 1/2" of ride height compared to right after they were installed, but this doesn't seem bad.

Ride quality has been great

 

[maidez]

I didn't have a 'before' measurement, so I'm not sure whether I ended up with a small amount of lift or not. Everything is back together, and with the new struts, lower ball joints, and tie rods, I can also say that my ride quality is much improved.