1 Ton Transfer Box Differences

[jcadwell]

I just bought a 69 IIA 88 with a 12J 2.5 NAD. It runs great, shifts smoothly, and leaks only a little. AND it is realllllly slow. Even with a Roamer Overdrive it feels like it is going to explode at 50 MPH. It also hits a brick wall at 55 and won't go faster, presumaby because of the rev limiter. It has the power to pull more, but not the gearing. I'm pretty sure the diffs have 4.7s.

In doing the math, it sure seems like the transfer case could have the 1.53 gearset from the 1 ton, especially since it has a 12J conversion. It would be running about 4000 rpm at 50, and hit redline shortly thereafter. The 1.15 gearset would sure make a difference if this is the issue.

Does the 1 ton transfer box have any external identifying features so I could confirm my gearbox?

Thanks,

John

[SafeAirOne]

Something isn't normal. My 2.5 will easily (well..."eventually" may be more appropriate) get my SIII to 55-60 mph without becoming too frightening.

Jack up one of the rear wheels and with the engine in 1st gear and the center coil wire disconnected (for safety) see how many revolutions you have to make with the hand crank before the raised rear wheel makes one complete revolution, then use the ratios on TeriAnn's website to figure out what sort of gearing you've got.

[SafeAirOne]

It appears that my method is flawed. Of course both rear wheels have to be off the ground and spinning in sync. Realized this when I read an exact copy of this whole thread, except from 12 years ago. The identification method for the 1 ton box is also described in that thread:

http://landroveraddict.com/forums/thread.cfm?threadID=3603

[SalemRover]

The roamerdrive wont fit a 1ton transfer case. How big are your tires? Every now and then I have seen some series with tiny tires on them. With everything else you mentioned It rules out the transmission tcase or overdrive. The only easily added diffs for a series would reduce the ratio from 4.7 to 3.54. That would cause the potential top speed to raise, and your sense of power would be non existant. It could possibly be driveline drag from brakes/parkbrakes, wheel bearings, or teeny tires. If I recall there was someone with a 2.5NA that was restricted on the freeway with dragging brakes. If you take it out for a jaunt on the highway you can put your hand on the wheel rim near the hubs (afterwards! ) and see if one is noticeably hotter than the others.

Jason

[jcadwell]

Thanks for the thread SafeAirOne.

So it's clear that I don't have super low gears. I also don't have overly small tires. I think they are 235-75-R16.

I took a drive this morning to enhance my observations. It has no problem getting to 50 to 55 miles an hour, it just sounds like the world is going to end. Around 40, I started to get a whine that gets louder with speed, and only when applying power or engine braking, so it ends up being most of the time. I'm thinking the whine is what makes so much noise, not the engine.

Coasting it goes away. It doesn't happen in low range at high engine RPMs, so I don't think its the transmission. It is directly proportional to speed, and only at high speeds. Changing gears or engaging/disengaging the overdrive doesn't change it. Pushing the clutch in or rolling in neutral makes it go away.

At this point I'm thinking rear differential. I twisted the rear driveshaft and it has almost 90 degrees of play. I'm going to try and confirm this by pulling the rear driveshaft and driving in 4 High.

If it is the rear diff, it looks like the ring gear can be adjusted into the pinion using the screw adjusters, and backlash set to around .005" with a dial indicator. Hopefully the gearset isn't too far gone to at least try it. I'm glad it's a third member style diff.

[SalemRover]

Sounds like the oil level in your transmission and or transfercase is low. The other possibilities are worn thrustwashers for the tcase intermediate gears, worn transmission mainshaft bearing, or synchro spring clip on its way out. I would start with the transmission and check the oil level. Don't ask how I learned all this...

[jcadwell]

I actually started there. The transmission was down perhaps 3 or 4 ounces, and the transfer case was full. Doesn't mean the seller didn't just fill them...

[SalemRover]

I had a very similar squeal to this last year coming home from the muddy chef challenge. It turned out to be the thrust washers in the xfer case. It did not squeal offroad in low range but whined on the highway to the point that earplugs were mandatory. I have read that a new roamerdrive gear dont always line up well with the intermediate gear and can whine considerably at first. Food for thought.

[Manny]

Oil level in the overdrive may be low. My Fairey gets loudet with lower oil levels

[jcadwell]

Earplugs are a necessity if I drive more than about ten minutes at 50... I've had this Rover about 6 days now, so I guess it is time to take it apart.

I think I have it isolated to the transfer box.

I took the rear driveline out, and drove in four wheel. No change, so it isn't the rear diff. The whine is directly proportional to vehicle speed. Shifting gears doesn't change the whine frequency. Shifting the overdrive doesn't change it, so at this point it can't be anything other than the bearings or thrust washers on the transfer case gears, or the mesh of the roamerdrive gear. I don't have the original gear to remove the roamerdrive, and don't know how long it has been installed... I guess I'll just rebuild the transfer box and see where it goes.

[SafeAirOne]

One thing you might consider doing if you are pretty sure that it is coming from the transmission/transfer case/overdrive area is to take the center seat hatch off and have somebody drive it while you probe the different components with a mechanic's stethoscope to see where the noise is originating.

[SalemRover]

Earplugs are a necessity if I drive more than about ten minutes at 50... I've had this Rover about 6 days now, so I guess it is time to take it apart.

I think I have it isolated to the transfer box.

I took the rear driveline out, and drove in four wheel. No change, so it isn't the rear diff. The whine is directly proportional to vehicle speed. Shifting gears doesn't change the whine frequency. Shifting the overdrive doesn't change it, so at this point it can't be anything other than the bearings or thrust washers on the transfer case gears, or the mesh of the roamerdrive gear. I don't have the original gear to remove the roamerdrive, and don't know how long it has been installed... I guess I'll just rebuild the transfer box and see where it goes.

Mark's stethoscope idea is a good one to be absolutely sure. Removing the tcase coverplate would allow you to inspect the gear teeth and slop in the thrustwashers. If you are lucky its just new thrustwashers and bearings there, or you could end up with a worn intermediate gear which would imply other challenges. The intermediate gear bearings and thrust washers can all be done without having to remove the driveline so its worth trying that first.

When I tore mine down the gear was worn past the point of use. The other problem is that it would have started to cut into the other gears that it mates with. This has a snowball effect as new gears mated to old worn ones could whine just as bad. I ended up rebuilding a separate unit. Not sure where you are but there is a rover event coming up in western ma where used tcases are plentiful, if you are as lucky as I am. Good luck with it!

Jason

[jcadwell]

I'll be pulling the cover and taking a look shortly. I'm in Washington State. I'm not sure I've ever seen another Series Rover on the road around here, let alone having a swap meet with parts available. Any idea what the going rate for a used transfer box would be?

[SalemRover]

They range in price quite a bit. I would make sure that it is absolutely beyond repair before getting one. They are expensive to ship at the very least.

[jcadwell]

I'm assuming that the thrust washer shouldn't be worn all the way through? There were no shims that I could find either. The intermediate shaft feels like it has a couple of thousandths of play on the small end of the shaft as well.