Transmission noise, strong blows

[Uri77]

Hello,
I recently bought an LR (santana) 88 series 3 from 1978.
it has a problem with the transmission. It makes a loud, dry noise, as if someone were hitting with a hammer.
Noise appears according to speed. The faster the blows sound faster.
When you go slow it doesn't make noise.

I do not know exactly what it can be if the transfer case, gearbox, transmission shaft and crossovers, differential.
I have done calculations and I believe that each time the blow is a wheel revolution. (more or less, 1-5 strokes per second, depending on speed)

He does it in the 1-2-3-4 march.
TRANSFER CASE:
-In the short transfer it is only heard very slightly in 4th gear with the engine at full throttle.
-With the long ones, he does it in all. When you go slow, no. It does so at 20km / h and the noise is progressive with speed.
-With the neutral of the transfer and the engine at full throttle it does not make any noise.

When you go fast (20-30km / h) with the clutch on it makes noise.
If you tighten the clutch (20-30km / h) the noise disappears.

This confuses me a lot because I thought it was the drive shaft and the cross braces.

At first I thought it was the front differential and removed the front driveshaft.

The noise seems to be from the front but, the truth with so little isolation, I don't know where it comes from. I am not ruling out the rear axle.

I have it 300km from where I live and the next time I go I want to have some idea where to look.

Can somebody help me.

Thanks

[Snagger]

Removing the front prop shaft (from transfer box to axle) will only eliminate that prop as a source.  The front axle internal shafts and diff will still be turning at road wheel speed.  The axle is a likely candidate from your description, possibly a broken tooth on the differential, or a bad bearing on a hub, shaft or diff.  I’d check the wheels by jacking up the vehicle and feeling for wobbles and roughness of rotation before another test drive, just in case a wheel bearing is failing, but it could be as simple as a loose wheel.

You could remove the drive flanges from the front hubs for a short test to see if it is a fault with the diff or half shafts and their bearings.  It’d leak some oil, but shouldn’t do any harm over a short distance.

[steve b]

Welcome to the forum

It could be a loose planet pin in a diff hitting the pinion face once per wheel rev. ? 

It could also be the handbrake shoes loose or oil contaminated dragging on the drum maybe - but that usually only happens at slow speed or when slowing to a stop .

12 minutes ago, Snagger said:

 

You could remove the drive flanges from the front hubs for a short test to see if it is a fault with the diff or half shafts and their bearings.  It’d leak some oil, but shouldn’t do any harm over a short distance.

If it still does it then replace front drive flanges and remove the rear propshaft and try it in 4x4 high , if it still does it remove the rear drive flanges and halfshafts and try it again 

Steve