TECH TALK - Page 2
One grease nipple - Two Destinations - By Owen McNeill
Nipples, they have always fascinated me, especially the ones for applying grease to mechanical components. There were so many different designs fitted to early cars while an early Ford Prefect that I once owned had twenty two of them to attend to. When just a young fella, I can recall my Father telling me to always clean the dirt from the nipple before attaching the grease gun, continue applying pressure until you see new grease emerging from the joint and always wipe away the excess grease when finished.
Over the past thirty years, they have slowly disappeared from the motor vehicle but my MGB GT still has a few and this is about a simple modification that I did to the swivel pin grease ducts -- I always called them king pins but I'll use the term used in the manual. On each swivel pin there are three nipples, the top one for the upper stub axle bush, the middle one for the lower stub axle bush and a bottom one, you would think, for the wishbone pivot bush but when I applied grease to this bottom nipple, none came out of the wishbone pivot bush, it all came out around the lower stub axle bush.
Remembering the distant advice from my Father, I dismantled the wishbone pivot expecting to find the hole in the bush not aligned with the grease duct but there was no obstruction and the joint was dry of lubricant.
The reason for this was that the swivel pin was drilled to supply grease to both the wishbone pivot and the lower stub axle bush [which had its own nipple anyway]. The grease always took the path of least resistance, the lower stub axle bush.
As the pin was almost new, it had been drilled this way so that it could be safely fitted to a very early model MGB which didn't have a nipple fitted to the lower stub axle bush. The manual goes to some effort to describe how to fit this nipple.
Removing the bottom nipple, I took a set of drills and found that the grease duct leading up to the lower bush was 7/32 diameter and extended 50mm past the cross drilling to the wishbone pivot.
Machining a piece of brass rod [wood or steel would do] to the same diameter and 50mm long, I tapped it up as far as it would go, blocking off the duct to the lower stub axle bush and replaced the nipple. Now, all the pressure and grease from the bottom nipple goes to the wishbone pivot.
If the rod is not tight enough to hold itself up in the duct, don't worry, the grease pressure will soon have it up there leaving the wishbone pivot duct open.