Gearbox Problems

**Mick_Marsh** · 22nd August 2010, 06:36 PM

Symptoms:
Speedo bouncing around and finally stopping.
With hand brake off and in neutral, vehicle difficult to push. Does not roll down slight rise.
There are no extra strange noises.

Tested:
Disconnected speedo cable at gearbox. Cable and speedo work fine.

Can anyone advise or guess what may be wrong with the gearbox/transfer case or advise what I should look at next?

**BigJon** · 22nd August 2010, 06:41 PM

Vehicle?

**Mick_Marsh** · 22nd August 2010, 06:44 PM

Sorry. Meant to put it in the title.
LT95
'81 RRC chassis and running gear.

**Bearman** · 22nd August 2010, 06:51 PM

Mick, Drop the rear tailshaft and check that the nut on the rear output drive flange is tight. If this comes loose it will affect the speedo drive and possibly explain some binding in the handbrake.

**Mick_Marsh** · 22nd August 2010, 08:56 PM

Is this a usual thing? Can it be really that simple?
I was mentally preparing for a gearbox rebuild or something major.
Worn bearings or dropped shaft at least.

**Bearman** · 23rd August 2010, 07:18 PM

Originally Posted by Mick_Marsh

Is this a usual thing? Can it be really that simple?
I was mentally preparing for a gearbox rebuild or something major.
Worn bearings or dropped shaft at least.

It could be Mick, as the speedo drive is locked between a distance sleeve and the rear drive flange which is secured by the nyloc locknut. It is important to use a new locknut whenever the drive flange has been removed/replaced to prevent it coming loose.

**Mick_Marsh** · 23rd August 2010, 07:39 PM

So.
To try and understand what has gone wrong.
The speedo drive has been replaced recently by others. Did the rear output shaft have to be removed to replace this shaft? This would explain why the nut would have come loose after ten plus years.

**Bearman** · 23rd August 2010, 07:50 PM

Originally Posted by Mick_Marsh

So.
To try and understand what has gone wrong.
The speedo drive has been replaced recently by others. Did the rear output shaft have to be removed to replace this shaft? This would explain why the nut would have come loose after ten plus years.

If the speedo drive worm gear was replaced, yes they would have had to undo the nut and remove the shaft. But the rear output housing has to be removed from the transfer case to allow the shaft to come out.

**Mick_Marsh** · 29th August 2010, 03:16 PM

Well, I removed the rear drive shaft today. The nut was tight. The hand brake drum spun freely. There appears to be no slop.
Any suggestions?

**Bearman** · 29th August 2010, 05:21 PM

If the rear shaft rotates freely the binding must be in one of the wheels/brakes, but back to the speedo. If you have checked the cable and it is ok and the speedo works when disconnected then the problem must be in the drive gear/worm. If the rear output shaft locknut is tight and no lateral play there I would expect the worm drive is ok as it is metal and sandwiched between the shaft shoulder and the distance sleeve. The only other thing it could be is the plastic drive gear which is located in the rear output housing. Where you disconnected the cable there is a round plug assembly that fits into the rear output housing. It has a lip around the edge and you should be able to get it out by levering gently under the lip with a small flat screwdriver. The speedo drive gear will come out with it and you should be able to see if there is any problem with it when you withdraw it from the housing.

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