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jeepguy03 03-29-2015 04:18 PM

Quadratec replacement leafs: standard or medium duty?
Quadratec offers three kinds of replacement leaf springs: heavy duty, medium duty, and standard duty. I know the heavy duty can give 1-2" of lift, but what is the difference between the standard and medium duty? Anyone have experience with these?

I searched but only found info using the heavy duty springs as a hybrid 2" lift. Which one would give no lift on a stock non-upcountry XJ? I first thought the standard ones, but read somewhere they might be for a 4 cylinder lighter weight XJ?


rjbruzan 04-01-2015 08:40 PM

Dorman springs from Rock auto or Advance w/coupon.

Charley3 04-02-2015 03:54 AM

Dorman springs are reputedly excellent, but there is nothing wrong with any of the Crown parts I've bought. I've had good experiences with various Crown parts, but I've not purchased their springs.
Crown is Chinese made, but so what? Some Chinese brands are good and I've had good results with Crown parts. The Crown rear hatch struts I bought were way better than what Oreilly carries for XJs. The Crown struts (and all their parts) are replicas of Jeep OEM parts and were a lot better than aftermarket parts that any auto store offered for door struts. The Crown suspension snubbers I ordered were BETTER than the Jeep/OEM snubbers that I also ordered. Probably because the Crown rubber snubbers were freshly made. The OEM snubbers had been sitting in a warehouse for 15 to 20 years getting old and hard.
You can also go to Rocky Road Outfitters where they sell stock OEM Jeep/Mopar springs for low prices. There's also various online OEM Mopar/Jeep parts stores - one of which is a vendor at this forum - see the vendor section.

Auto stores sell Dorman (as one of their best brands). Quadratec (and other places) sells Crown. Rocky Road Outfitters and various OEM/Mopar parts places sell original OEM springs, but only Rocky Road has OEM springs for good prices.

Charley3 04-02-2015 04:00 AM

As for the differences between the springs mentioned in the OP. I assume its exactly what the name of each implies.

The standard duty will sit the lowest, ride the softest for most comfort, but can't haul much cargo weight. If they're like OEM standard springs they might (barely) clear 30" tires.

The medium duty (I think, but can't promise) are probably like OEM tow package springs. If so, the XJ would sit about 1/2" to 3/4" higher, have a lot more load capacity, and ride semi-rough, or borderline for comfort, and easily clear 30" tires. I had tow package springs when my XJ was stock.

The heavy duty spring (I think, but can't promise) are probably like OEM Up Country springs. If so, the XJ would ride very rough, but have a lot of load capacity. It'd ride 1" to 1.5" higher and easily clear 30" tires. IMO

XJFrance 04-02-2015 07:40 AM

Qaudratec Heavy Duty
Quadratec Heavy Duty springs will net you almost zero lift (stock height) by the time they settle. True, you will initially be 1.5-2" over stock height when you first install, but they will settle out. I put them on my wife's XJ last spring, and they settled out to stock less than a week later after hauling my tool case back home.

I ended up putting in a +2" add-a-leaf/helper spring to get the 2" over stock height. They are decent springs if you want stock height though. Otherwise I would go with the OME.

XJFrance 04-02-2015 07:53 AM

Assume with all these springs that you are going to be stock height or near stock height by the time everything settles in. The difference is the spring rate. So, if you want something nice and cushy, but will sag (well below stock height) when you put weight/cargo in the rear; then the standard will provide that. If you want something that is very stiff, and will sag very little as you pile in the pounds in the rear; then the heavy duty will fit the bill. The medium duty is just somewhere in the middle. I have been very happy with my wife's setup, the HD +2", using the Jeep JK Rubicon shocks. It is a little stiff (its a truck, not a Lincoln), but it feels very stable, and tight.

I drove home for Christmas, I had 2 adults in the back, a 100# malamute, a hitch cargo basket with ~200# of stuff, and a cargo basket with another 150# of stuff. I think I was sitting right around stock height fully loaded.

cbenez1 04-02-2015 09:54 AM

My brother put standards on his 2000 and did not like them they sagged after a year. Ride quality was decent. As for the question of lighter duty springs being for a 4cyl ? Negative the original rear leaf springs are no different between 4cyl and 6cyl XJ's because the weight difference is completely up front.

cbenez1 04-02-2015 10:02 AM

I've tried many different set ups on my various XJ's from add-a-leafs (never again) to doctored up 3/4 ton leafs. The set up I prefer hands down is a stiffer spring with a heavier shackle angle. Shackle relocation brackets were the best $150 I ever spent on my current DD 01. If your interested check my thread. Search "3/4 ton dodge van leafs". Not saying you need that heavy a set up but with right shackle angle you can adjust the ride to your needs.

jeepguy03 04-02-2015 10:51 AM

So in other words the medium duty springs would probably be the best for a stock XJ? It sounds like they won't sag as quickly like the standards but won't give 1-2" of lift.

XJFrance 04-02-2015 11:07 AM

Lets be clear here, YOU WILL NOT get ANY addition lift from any of the leaf packs. Heavy duty sits about 1-2" over stock for maybe a week, then will settle down to stock height. As the previous poster mentioned, mediums will sit at stock height, but will sag (ride lower than stock height) after some time possibly. So, again, these would all be for stock height, but the REG, MED, and HD will depend on how stiff you like them and how they will remain at stock height (+19" in the rear I believe) depending on how much weight is in the back.

Heavy Duty will remain at stock height with several hundred pounds in the rear, which in my option is kinda nice and the point of an SUV.

Charley3 04-02-2015 01:54 PM

My 96 XJ had OEM standard duty springs when it was stock. My 99 XJ had tow package (medium duty) OEM springs when it was stock. I bought both XJs with 33K miles on them. So same mileage and neither had been off roaded before I bought it.

I had 29.5" tall tires on the 96, and 29.8" tall tires on the 99.

The 96 (std duty springs) 29.5" tires rubbed the flares slightly when flexing off road. The 99 (med duty springs) never rubbed a flare when flexing off road. The 99 sat slightly higher and that was apparent to the naked eye. So IME the med duty springs sit slightly higher than std duty springs. Enough higher to fit a 30" tire without rubbing, IME.

Those ^ were my experiences with the stock OEM std and med duty springs. I assume the same applies to the std and med duty Crown springs sold by Quadratec that the OP asked about, but I'm not sure.


I've never had stock heavy duty springs, but I've always heard that stock OEM heavy duty springs ride about 1" higher (perhaps slightly more) than std duty springs. The "Up Country" or "Off Road Package" XJs had the heavy duty springs and 30" tires and had approx 1" lift compared to standard duty springs. That's what I've always heard and read about them.

I assume the same applies to the heavy duty Crown springs sold by Quadratec that the OP asked about, but I'm not sure.


P.S. - I'm referring to rear springs here.

Charley3 04-02-2015 02:05 PM

How much cargo weight do you need to carry in the rear cargo area? How much ride comfort (when no cargo) do you want? I'd let those things guide you to which spring to get. Don't worry much about ride height since it's not much different between any of them.

The stiffer the spring, the more load capacity, but the harsher the ride will be when not carrying cargo. Keep that in mind when you choose and also keep in mind how much weight do you need to haul? (including gas tank skid plate and aftermarket bumper, if any, in addition to cargo)

jeepguy03 04-02-2015 04:16 PM

The XJ in question is otherwise stock and may haul a small trailer a few times a year with a mower on it. Most of the time it has nothing in it but a driver.

Charley3 04-02-2015 08:20 PM

Well then, std or med duty spr would be fine.

If you have a healthy spine and can handle a somewhat firmer ride, then get the med duty. Then you could haul more if you ever want to.

If you need a softer ride (like I do with my spine problems) get the std duty.


Charley3 04-02-2015 08:29 PM

If you get std duty and later need to haul more stuff than it can handle, you could change rear shocks to Monroe Sensatrac heavy duty coil over shocks, or maybe air shocks.

However, for ride comfort the regular Sensatrac are excellent with std or med springs. I've used the regular Sensatrac with std springs on my 1st XJ, and with tow package (med) springs on my 2nd XJ.

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