Oil on steering and main brake rotors

[sexton]

We've got a Striker CVRT that is reported to have poor steering. Hydraulics are fine, no leakage and about 3" of tiller movement before brakes apply hard. But steering brake rotors and main brake rotors are coated with oil.  Pads must be saturated too. This is only the second CVRT I've worked on but looking at final drive and gearbox cross sections, it looks like it might be final drive axle seals or gearbox output shaft seals leaking, or both. Is this a known problem?

Malcolm 

[Grasshopper]

Could be the seal in the final drive output (quill) shaft. I've had that on a Sultan we once had and we removed the final drive to renew the seal. Although heavy, it's not too bad a job to do. We walked the final drive out on to some timber packing, pulled the shaft, old seal off, then refitted it all. Including breaking the track, about 3 hours work. We also had a leak on our Spartan final drive, and this turned out to be the ring of bolts around the outside (which should have been lock wired) were all loose! 

I'd suggest a good clean up and then try and identify where the leaks are originating from. 

[sexton]

Yes, the final drives don't look too bad to get off to replace that input shaft oil seal. But as you say, I need to pin down the leak source first. I had slight final drive seal leaks on another CVRT but it only contaminated the main brake rotors, not the steering rotors, which is kinda what I'd expect. The fact that both sets of rotors are oiled up might mean there are multiple leaks. And I see there are two gearbox oil seals that can leak onto each steering brake rotor. 

I guess I'll give the steering brakes a good clean to see if I can get some steering back and test drive and find the leaks when the weather warms up. 

Thanks,

Malcolm

[Grasshopper]

Our Spartan issue came to a head following loading onto a transporter truck. The steering was fine when I loaded up, then she got rained on  and when I unloaded (I think there was a period of storage between these events), the steering was gone! I assume the water level in the gearbox compartment caused the steering brakes to become contaminated due to the angles the vehicle achieved on the loading ramps. That and being the oil/water being thrown around by the rotating cooling fan and brake disks. Anyway that led to the eventual discovery of the final drive being the issue. 

[sirhc]

The steering brake discs can easily become contaminated with the oily mess that collects in the gearbox bay when it gets rained on. I always keep a spare set of pads and a can of brake cleaner in one of the front bins for this purpose. 

[Diana and Jackie]

I leave a bolt out of the inspection plate below the gearbox oil drain, any water drains out, also goes to show if there's an oil leak. Do the same for the sump inspection cover..

 

Diana

[sirhc]

Leaving a bolt out of the inspection plate is a good idea, if you have one..... 

[Diana and Jackie]

Surely not beyond you to make one Chris? :-)

[sirhc]

I know this is off topic, but the uparmoured ones have an air gap filled with foam between the hull and the steel plate. If you drill a hole through it the cavity could fill with water which would be bad!

[sexton]

That's an interesting point about small oil leaks accumulating on the floor and getting up onto all the rotors after heavy rain. I did find it a bit surprising that all 4 rotors were contaminated. Seemed like a lot of seals would have to be leaking. I'll keep my fingers crossed. 

Both vehicles have the foot operated drain valve for the gearbox compartment but that's a good idea about leaving a bolt out of the access hatch. I'll do that. 

Chris, when I drilled drain holes, I was drilling through about 1.5" of solid aluminum all the way, so I guess we don't have the uparmoured ones here. If I had hit an interspace and then seen foam "filings" coming up, it would have been an "uh-oh" moment. 

Malcolm

[sexton]

The steering and main brake pads were soaked in oil as expected, so I cleaned them with brake cleaner and then baked them in the oven at 400F for 10 mins. Some remained clean, but oil was just bubbling out of two of them and others were filmed over with oil. After cleaning, I put them back for a second bake. The ones that filmed over now remained dry but the two bad ones were still bubbling out oil. One took one more bake and the other took 2 more bakes before oil stopped coming out. 

I'm impressed with this technique, but I didn't understand what is happening. Mineral oil doesn't boil until about 300C, so it wasn't the gearbox oil actually boiling out. Yet there it was, bubbling away on the surface of the pads. I found an EBC tech memo that explained that the phenolic resins in organic pad materials off-gas under heavy braking. This off-gassing is what causes brake fade in extreme conditions (pad material getting up to 1000F). So I think some off-gassing is occurring at 400F and that is driving out the soaked-in oil. 

Malcolm