Mopar 52059912AC Front Upper Coil Spring Isolator for 07-18 Jeep Wrangler JK

A rubber pad under the coil spring is one of those inexpensive parts that can spoil the feel of a whole vehicle. Once the rubber ages, flattens or breaks up, the spring starts working metal against metal — you hear knocks over speed bumps, the front sits a few millimetres lower, and vibration goes straight into the body.

This is the genuine Mopar part, number 52059912AC — the upper isolator for the front coil spring on the Wrangler JK. It supersedes the earlier 52059912AA and 52059912AB, so it also fits vehicles that left the factory with the older revision.

Key benefits

• Genuine Mopar — factory rubber compound and factory thickness, so the front returns to its designed ride height rather than a random one.
• Current AC revision — supersedes 52059912AA and 52059912AB, so you fit the part number in force today.
• The whole JK generation — 2007-2018, 2-door and 4-door Unlimited, 3.6 and 3.8 V6, right-hand-drive variants included.
• Cheap part in an expensive job — with the front suspension already apart, swapping the isolators takes minutes and costs the least of anything you will touch.

Technical data

• Mopar part number: 52059912AC
• Catalogue name: ISOLATOR Spring Upper
• Position: front axle, upper isolator
• Superseded numbers: 52059912AA, 52059912AB
• Material: rubber
• Thickness: approx. 3/4 inch, about 19 mm
• Vehicle: Jeep Wrangler JK, model years 2007-2018
• Engines: 3.6 V6 and 3.8 V6
• Trims per the catalogue: X, X RHD, Sport, Sport 4WD, Sahara, Sahara 4WD, Rubicon, Rubicon 4WD, 70th Anniversary, plus Unlimited Sport, Unlimited Sahara, Unlimited X and Unlimited Rubicon in 2WD, 4WD and RHD 4WD form
• Sold individually (price is per isolator)
• Catalogue weight: approx. 0.36 kg (0.8 lb)

Who it is for

For JK owners hearing knocks from the front at low speed over rough surfaces, and for anyone stripping the front suspension for another job — springs, shocks or a lift install. Ten-year-old rubber will not recover on its own, and replacing it costs a fraction of everything else in that job.

Fitting notes

The isolator sits between the top coil of the spring and its seat in the body, so replacing it means unloading and removing the spring — routine work once the front suspension is apart. The price is for one piece and the vehicle has two front isolators, so a full axle takes two. Doing the whole vehicle at once? Add the rear isolators as well — we stock them under 52059999AC.

Why buy this one

• Factory rubber instead of an equivalent of unknown hardness and thickness.
• One number covering the entire JK generation, with no split by year or engine.
• The cheapest item in the front suspension — not worth saving on with the spring already out.

Not sure whether your JK has had these replaced already? Send us the VIN and we will confirm the numbers and put the rest of the parts for the job together.

Frequently asked questions

Is this the front or the rear isolator?

Front, upper. The rear-axle equivalent is 52059999AC — a separate part with a different shape; the two are not interchangeable.

How many do I need?

The price is for one isolator and the front axle has two, one per spring, so a complete front takes two pieces.

Does it fit both the 3.8 and the 3.6 JK?

Yes, the catalogue lists both engines. The same number covers the whole JK generation from 2007 to 2018, regardless of engine or number of doors.

Will this lift the vehicle?

No. It is the factory component, about 19 mm thick, which restores the original ride height and damping — it is not a lift spacer. For extra height you need spacer pucks, not this part.