I won a set at the CM raffle, don’t take this as me being ungrateful, have great respect for Marlin and what he has done for the Toy wheeling community. I just don’t see these being a big upgrade on the ‘80. The mini’s, ‘40’s, etc, have smaller seals of different design, many users weld trusses, etc to the housings warping them, so need all of the help they can get.
The axle/birf is only held in place by relatively loose splines and snap-rings, as the axle rotates and steering turns there is some lateral movement at the seal, it doesn't run perfectly concentric. IMHO there will always be some slight leakage, burping between the diff fluid and grease.
I don’t have an OEM seal, so using one from a Cruiser Outfitters kit for comparison. It has a metal outer ring, the seal rubber is attached to the outer ring with a bellows type web of rubber allowing for lots of misalignment. The seal area is supported by a coil spring to provide even tension around the axle.
The Marlin seal is much more rigid, has less flexibility. The seal is attached to the inner flange of the metal and only supported by a wire ring, IMHO wont seal as well when operated in misalignment. Measuring them, the Marlin looks to seal ~1/8” further into the housing, so maybe a help if you have deeply grooved axles? The lack of flexibility may increase wear of the axle and/or seal?
It’s not like a rear main seal where you want it to run drip free for 250K+ miles, the axle needs service, so the seals only need to last a fraction of that. IMHO it’s a pick your poison, tossup thing, I have the Marlin so will run them, but would be just as confident in the original type seal, they are well proven to go the service distance plus.
