1992 Mack RD688s Steering Gear Drama

[KP2]

The steering gear was leaking by the input shaft.  I was told I could take the top off and replace the seals.  After removing the top I discovered the shaft had a groove in it.  On these forums the only option after finding the groove I saw was to buy another gear.  I tried putting JB Weld in the groove and turning it back down on a lathe, installed new seals.  It held for a few minutes then started leaking again.  Removed shaft again, installed wear sleeve and new seals.  I ran it about two hours and it started leaking again.  I searched for days and could only find one gear through Watts Truck.  Weller would reman one for me but they had to have mine first so that would be a drawn out deal.  So I have ordered the one through Watts.  It was $2500.  I called a few salvage yards and could not find one.  Several places I called wouldn’t even bother to answer the phone or call back after I left a message.

I had considered taking the shaft to a machine shop, have the groove welded up and then turned down but was not sure about the integrity of the shaft after doing that.  Anyone ever done that before?

Is there anyone on these forums with a RD688 that has had this same experience?  If so what did you do?

 

[mowerman]

if the 2500 includes shipping your not going to do much better i found an outfit in florida that sells rebuilt for around 900 plus shipping another 900 depending where you are is it a sheppard or a ross box???

[Vladislav]

Fixing the shaft condition could be the way to go. Lathe work is Ok if you dial the shaft's center well enough before cutting. Grinding in a machine is much better and preferrable option. Welding is no of good options since the shaft is (should be/ could be) made of high carbone steel. Which doesn't weld well and could easily crack through in the welded area later in service. So application of material (metal) on the area could be halvanic (chrome) or ultrasonic metal powder coating. I don't know which kind of technology could be found in your neck of the woods but strongly advise to get off of the idea to weld up.

Also an option might be cutting/grinding the shaft over the worn area to lesser OD. Than locate a seal with lesser ID (and the same mounting size) using a chart or catalog. For example Timken offers a wide range of industrial seals and their catalog is on-line. Not almost correct way of fixing things but could be applied.

[Geoff Weeks]

If it is a Shepard gear, I think the correct repair is to cut the shaft to a smaller OD and shrink a sleeve on where the seal rides. You could possibly have the sleeve made from hard chrome stock, making the repair better than the original. 

These repairs need a qualified machine shop that can do the work. It would take tooling that can cut the hard shaft and sleeve.

I was working on a car that had some brake parts that are NLA anywhere, my machine shop made a repair like the above and was surprisingly reasonable. You just have to think "outside the box" and remember anything made by man can be re-made by man.