sexton Posted July 3, 2016 Share Posted July 3, 2016 We drove a Ferret about 15 miles to a Canada Day parade with no problem but during the parade, it started to knock once loudly when braking to a standstill. This was coming from LHS front, outside the hull. By the end of the parade, the knocking was much worse. Multiple knocks, erratic, not related to wheel speed, like someone hitting the outside of the hull with a hammer, and only when drivetrain was loaded. I could feel the impact on the hull from the inside. When coasting downhill, i.e. unloaded, there was no knocking. No obvious loose suspension parts. Pulled the brake drum off and no breakage or loose parts. For info, I dismantled the hub a while back to replace the brake backing plate. Anyone experienced this ? Malcolm Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted July 3, 2016 Share Posted July 3, 2016 We drove a Ferret about 15 miles to a Canada Day parade with no problem but during the parade, it started to knock once loudly when braking to a standstill. This was coming from LHS front, outside the hull. By the end of the parade, the knocking was much worse. Multiple knocks, erratic, not related to wheel speed, like someone hitting the outside of the hull with a hammer, and only when drivetrain was loaded. I could feel the impact on the hull from the inside. When coasting downhill, i.e. unloaded, there was no knocking. No obvious loose suspension parts. Pulled the brake drum off and no breakage or loose parts. For info, I dismantled the hub a while back to replace the brake backing plate. Anyone experienced this ? Malcolm Hi Malcolm, If this is what I think it is, I have dealt with it on numerous occasions, with Ferret as well a Saracen, Stalwart, Fox, etc. It could well be a metal deposit between the a tracta fork and knuckle on an outer tracta joint. Due to localised heat a pit occurs on one part and a deposit on the other and when driving in a straight line this does not create any or much noise, until you steer off centre and the pip is then not aligned with the pit and then knocking occurs. What you could do is jack up both wheels one side and get someone to turn the rear one and watch the front wheel, if you have the steering slightly one way you may notice the wheel kick as it turns. Depending on how big an area is damaged it is permissible to stone down the damaged to regain working clearance, the pit actually serves as an oil retainer, just depends how bad it is. regards Richard Quote Link to comment Share on other sites More sharing options...
sexton Posted August 30, 2016 Author Share Posted August 30, 2016 Update: it was the inner tracta joint that partially seized due to low oil level. Our mistake, obviously. The long drive generated enough heat in the joint to blue the steel. As Richard said, the ensuing galling created high spots on one face and low spots on the mating face. So under load they locked together and prevented the faces sliding. The inner joint only pivots vertically to accommodate suspension movement up and down, so it didn't knock when turning, just when loaded. The tracta joints look particularly susceptible to low oil level because their small diameter means they loose the oil splash sooner as oil level drops. Another question: we have no spare left front/right rear bevel box so I need to steal parts from some spare right front/left rear boxes we have. But the bevel gear design in the spares is significantly different. The bevel gear is one piece, incorporating the hub, unlike the original gear which has the hub riveted to the gear. Also the tapered roller bearing between the tracta joint and the bevel gear is much larger than the original. See the photo of a good spare below. Are they interchangeable? It looks a bit laborious setting up the bearing preloads, lash, and tooth contact without the special tooling in the manual. Malcolm Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted August 30, 2016 Share Posted August 30, 2016 Hi Malcolm, I was pretty sure it would be a tracta. The problem is when topping up the oil, people often think that when the oil globs out of the hole as soon as they start filling, that it is up to level, whereas it is air pushing the oil back out of the horizontal level tube. The trick is to use a hand pump of low volume output with a small pipe that can be inserted right up the tube and thus letting air out as you fill, this is useful on other top up points as well. I have a converted grease pump which have been using for 20 years on many type of vehicles without issues. regards, Richard Quote Link to comment Share on other sites More sharing options...
Starfire Posted August 30, 2016 Share Posted August 30, 2016 When I fill my hubs/bevel boxes, I use a small hand pump with a nozzle as well, and I also go around and around the vehicle, so I start with FR then RR, then RL then FL and then back to FR and so on to check them again. It takes a while, but is the cheapest insurance you can get. Quote Link to comment Share on other sites More sharing options...
sexton Posted August 30, 2016 Author Share Posted August 30, 2016 Richard, Have you seen the two different types of bevel gear assemblies we have? Here are photos of the original bevel gear with the rivetted on hub. The photo of the spare one we have with the solid hub and separate spacer is above. Malcolm Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted August 30, 2016 Share Posted August 30, 2016 Malcolm, I have a part list that was updated right through to when Ferret went out of service, the page with bevel box details is an amended one and the picture shows gear and hub in one. The riveted one was prone to shearing rivets and I suspect these boxes only crept into the fleet when an earlier type failed. regards, Richard Quote Link to comment Share on other sites More sharing options...
sexton Posted August 31, 2016 Author Share Posted August 31, 2016 Thanks, Richard. Yes, the later style does look much stronger. Malcolm Quote Link to comment Share on other sites More sharing options...
OZITIM Posted September 1, 2016 Share Posted September 1, 2016 Ive got NOS spares still in the timber crates. I dont know what the postage cost would be. They arnt exactly light. Quote Link to comment Share on other sites More sharing options...
OZITIM Posted September 1, 2016 Share Posted September 1, 2016 Ive got plenty of NOS tracta joints in boxes too. Quote Link to comment Share on other sites More sharing options...
sexton Posted September 2, 2016 Author Share Posted September 2, 2016 Thanks for the offer, Tim, but I think I've enough parts now to fix this one now. Malcolm Quote Link to comment Share on other sites More sharing options...
OZITIM Posted September 2, 2016 Share Posted September 2, 2016 No problems mate. Let me know if your stuck. Its no problem to put something in the post. Quote Link to comment Share on other sites More sharing options...
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