Magnet in differential housing?

[Gaugster]

I have my Ford 9" completely disassembled for a rebuild. Is gluing a magnet to the bottom interior a good recommendation? Picture shows the JB weld and magnet I could use. One of my books suggested to do so for a little extra insurance. New 3.89 ring and pinion, Moser 31 spline axles and a Powertrax Grip Pro (spiral gears) posi.

[winr1]

If ya have a welder or Friend that can... weld a drain in the bottom of ya housing while the 3rd member is out

Install a magnetic drain plug bolt ... or install the magnet



Ricky.

[Keith Stevens]

My 67 GT 500 has a magnet in the bottom of housing that is a donut shape. Being it's a pre-may 67 car the fill plug is in the back of the housing. I don't see how a magnetic fill plug would be of any value above the oil level.

[RustyCrankshaft]

A magnetic drain plug is probably the easiest if the housing has a drain. But an epoxied magnet in the housing is good too. We had a bunch of Rockwell R170's at work in a fleet with very short drivelines and they kept eating pinion bearings. Rockwell's solution was to JB Weld magnets in the housing as their sales pitch was it isn't a design problem but residual contamination. It didn't solve the pinion problem, but it did prolong the life quite a bit. Amazing how much crap they would catch.

[The Real McCoy]

I’m not sure it’s necessary to JB Weld the magnet to the housing, especially if it’s on the bottom of the housing. If you somehow launch the magnet off the bottom of the housing that would be the least of your worries. LOL

[machoneman]

I’m not sure it’s necessary to JB Weld the magnet to the housing, especially if it’s on the bottom of the housing. If you somehow launch the magnet off the bottom of the housing that would be the least of your worries. LOL

I've never seen the need as on teardown the gear lube I've seen doesn't show any metal flakes. But, I'd instead slap a magnet, as noted, on the OUTSIDE of the housing as it would serve the same purpose. That or or drill it for a magnetic drain plug as then one could easily drain it for a fluid change and check for metal particles.

I do so on stick trannys, especially new ones, just to be sure any machining/assembly crap gets caught by the magnetized drain plug.

[Falcon67]

Last time I saw metal in a rear end, the 90w looked like murky silver paint.  Not much that a magnet would do to help that.  Agree with doing a drain plug on the bottom of the housing, mag plug or not.  Mine does not have it and I wish it did, primarily for ease of draining to switch center sections.

[RustyCrankshaft]

I agree epoxy is not necessary, but using the JB Weld was the axle manufacturers procedure and since these were all warranty supplied parts we followed their process. The magnetic did extend the service interval. We went from around 260k miles on a diff to consistently over 300k.

In most performance/street car applications I'm not sure it helps as the oil tends to get drained quite often in terms of mileage so unless something is coming apart there is a pretty low level of contamination.