View Full Version : Grease zerks for rack and trunnion

09-23-2006, 11:51 AM
I am trying to do the lube maintenance for the 6. I got the rack lube by using a 1/8 inch zerk but it is really pipe thread so I just started it and got the job done.
But the trunnion seems to be 5/16 inch. Are these straight thread or British Pipe or ?
Where can they be obtained?
Also the rear drive shaft ujoint zerk seems to be impossible to fit the gun to due to minimum clearance between the ears.
Any tricks here. Old posts talk about not greasing at all and using Spicer parts. Whats a guy to due until he needs to replace joints?

09-23-2006, 12:09 PM
The grease fittings can be obtained from Moss Motors (https://www.mossmotors.com/Home.aspx)

and probably others like TRF...

09-23-2006, 01:54 PM
Thanks, True, but this only seems to cover the ball joint and the steering rack and the vertical link. Nothing about the trunnion. I was also trying to figure out the actual thread style. Bikes use British standard fine or BSP, etc.

09-23-2006, 02:16 PM
The trunnion is lubricated by the zerk on the lower part of the vertical link. Whether it is grease or oil, the lubricant passes down through a passage in the vertical link into the trunnion. The trunnion to the lower wishbone does not have a provision for lubrication.

09-23-2006, 04:57 PM
Hi Norton,

The trunnion zerk is a fine pipe thread, if I recall correctly. I found them easily at a local auto parts store (just bought a package that had a selection of sizes in it, and one of those worked, so I'm not able to tell you the size for certain... 1/8" ISTR).

Also not totally sure if it's BSP thread or not, almost certain it's not. But it doesn't really matter. British pipe thread and US pipe thread are so close, either will work. In fact, I've often seen USP deliberately mixed with other BSP threaded fittings on cars, because the slight interference fit makes it less likely the fitting could ever rattle loose.

Yes, the grease port on the top of the R&P has a straight thread, not a pipe thread. I have a couple modified zerks I made up for use there, simply by carefully re-cutting their threads with a die. I seem to recall it is 3/8" x 24 (NF) thread fitting. It's impossible to cut the new threads all the way down to the shoulder of the hex, but even so the zerks work fine for the occasional lubing of the R&P.

The trunnion to the lower wishbone does not have a provision for lubrication.

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True on TR6. But, actually, there are grease fittings for these on TR4 and earlier, which have honed bushings running on the horizontal steel pin.

OTOH, TR4A and later cars with the nylatron bushings and large "bolt" don't get greased.

09-23-2006, 05:44 PM
Gottcha the location of the zerk of the trunnion was throwing me off. The verical link zerk is in place and I have lubed it. Sounds like I am off to the next project.

09-24-2006, 07:03 AM

Also not totally sure if it's BSP thread or not, almost certain it's not...

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I took the trunnion and upper ball joint fittings out of my TR3, and measured them. They are 1/8"-28, which is BSP pipe thread. Yankee pipe threads are 1/8"-27 (NPT). Of course, this is on my TR3, other models may be different. As you state Alan, the 1/8"-27 is so close, that in this application it will not make a difference. In some applications it will make a difference. On my Miata, the oil pressure sensor is threaded with the British 1/8"-28, and if you put in a sensor that is 1/8"-27, it will leak.

09-24-2006, 11:21 AM
The rear drive shaft u-joint zerk is indeed hard to get at.

The drive shaft flange, however, is not symmetical. If you look hard at the drive shaft u-joint flange, one side of each flange 'ear' has a concave curve in it to allow just enough space to get a grease gun nozzle into. The other side of the 'ear' is straight.

When the u-joint is installed, you need to ensure that the hole for the zerk fitting is facing forward (i.e. toward the front of the car), and ALSO that the u-joint is oriented so that the zerk will stick out on the drive shaft side that has the curve. If that wasn't done when the u-joint was fitted, you won't get at a standard zerk.

Unfortunately, I have learned this from experience.

The only other thing to suggest regarding the drive shaft is to install a 'needle' zerk fitting. You can get them at NAPA. The needle zerk is a standard fit (1/4"-28 pitch I believe), and has a minimal-clearance flat head. You can get a needle fitting for the end of your grease gun, and presto, you can get at the fitting.

09-24-2006, 11:13 PM
I will check that out Monday.

09-25-2006, 06:35 PM
FYI, the Napa number on that flat-head zerk is PUJ621. They don't show a price on the NAPA website, and they indicate it is an in-store item only. I have got them from an auto-parts dealer here in Canada, but Napa Canada said they couldn't get them.

I have attached a picture from the NAPAOnline catalog.

As a suggestion, you might think about using a hacksaw to cut a straight kerf across the top of the zerk so you can use a flat screwdriver to snug it down into the u-joint. I found that even the flat zerk was tough to tighten down against u-joint, since its hard to get a socket in there.