LT95 Transfer Thrust Muncher

captainslow · 15th April 2016, 05:02 PM

I'm looking for some help diagnosing the cause of some rather drastic thrust washer munching in my recently rebuilt LT95. This resulted in loss of Hi Range (a long way from home - but that's another story...)

Here is what happened at the Low Range end of the Transfer Intemediate Shaft

You can see that the outer most Thrust Washer is toast. And the next Thrust Washer in line is on the way out.
The outer Thrust Washer has ground itself into both the Low Range Gear and the Outer Pinned Washer. It has also deformed badly - so much so that the Inner Washer won't fit inside it and has pushed itself into the roller bearing.

So, my observations:-
1. Oil is Castrol GTX Diesel 15W-40
2. Oil was black and sludgy as you'd expect with the damage (but no glitter - because no brass)
3. Oil channels in the Intermediate Shaft were all clear
4. Only the Thrust Washers each side of the Low Range Gear were damaged. Thrust Washers either side of the High Range gear had no wear.
5. Running behind a N/A ISUZU
6. About 800km of use since the rebuild with no unusual noise (but who can tell with a 4BD1).
7. At the rebuild the Hi Range Gears were changed to the .996 ratios using a set supplied by Craddocks.

So what have I done wrong to cause this sort of damage?

It seems that all of the axial thrust is coming from the Input Gear. Is there a right and wrong way around to assemble this gear onto the Intermediate Shaft? I can't see any method of orientation - but the force does seem to come from this gear towards the Low Range end.

Just to clarify my terminology regarding part numbers:-
Thrust Washer = FRC3500
Low Range Gear = 591891
Outer Pinned Washer = FRC6284..8 (selectable thickness)
Intermediate Shaft = FRC3507
Inner Washer = 591900

If the normal brass Thrust Washers had been used I think I would have know within about 10km but the steel washers have held up well in trying circumstances and done a bit of damage as well. I imagine the steel will be very good in the long term if I can get this problem sorted.

Any help most appreciated.

Pete

**Bearman** · 15th April 2016, 05:55 PM

Hi Pete, That's very unusual and bad luck after a rebuild. I don't know what has caused this if it was set up with the correct clearances, mind you I haven't seen one with steel thrust washer only brass. It doesn't matter which way the input gear is turned - it performs the same in either position. The outer pegged thrust washer shows signs of excessive heat which should not happen. It sort of looks like the steel thrust washer might have stuck to low gear and started heating the pegged one up and wearing into it and then wore into low gear as well. Did the steel thrust washer have oil channels moulded into both surfaces like the brass ones do?
Let me know what thickness the outer pegged one is and I will have a look through my spares. Fair chance I will have one as well as a good low range gear. They are yours for the cost of postage.

captainslow · 15th April 2016, 06:27 PM

Thanks for the help Brian.

So you've ruled out the only thing I could think of. It sure must have generated some serious heat so there must have been significant force involved.

I haven't tried this before but I think I'll try some gear marking method (prussian blue?) to see if there is some mismatch happening in the gears. I'm not comfortable putting this back together until I can find some explanation.

Thanks for the offer of the Low Range Gear and washer. I'm pretty sure I have usable spares from a third box that I bought but I appreciate the offer if they don't look right.

Yes, interesting the steel Thrust Washers, I'll do some research on that...

I'll throw up the results of the gear contact tests once they're done.

Cheers
Pete

**Bearman** · 15th April 2016, 06:30 PM

You know what the ultimate answer is - a TRB intermediate shaft.

captainslow · 15th April 2016, 09:37 PM

Ha! You've got me at a weak moment.

From what I've heard TRB runs cooler, runs longer and doesn't require any maintenance - where's the challenge in that??

If I can get my hands on one I'd put it in like a shot.

But, I'm still worried about this muncher. I'm guessing that whatever is wrong with this transfer would have given TRBs a bit of a fright too...

**Busted Syncro** · 16th April 2016, 10:09 AM

G'day Pete,

Looks like a major loss of lubrication on those steel thrusts with Metal to Metal contact producing all that heat.
My experience with Bronze thrusts is you cannot use a GL5 (EP) type oil. You must use a GL4 manual gear oil for Bronze thrusts.
Hence GTX is OK for bronze thrusts as specified in your Transfer G/B.
However for steel thrust maybe you need a GL5 (EP) type oil.
What are the recommendations for your Transfer G/B using steel thrusts regarding Oil type GL4 or GL5?
Chris

captainslow · 16th April 2016, 04:42 PM

Originally Posted by Busted Syncro

Looks like a major loss of lubrication on those steel thrusts with Metal to Metal contact producing all that heat.

Chris, that's an interesting point. Having a look around the net, for the Thrust Washers part number FRC3500, it seems that Britpart supply steel and AllMakes supply bronze (and I'm guessing genuine are still bronze). Mine were the Britpart make supplied by Craddocks in the UK.

I'm no expert on oils but I take your point that engine oil may not be good enough for steel thrusts. So, maybe a better oil may make all the difference. I'd be loath to use a GL5 oil just in case it migrated into the main gearbox and harmed the synchros, but maybe a gear oil like Castrol VMX-80 may do the trick.

But having said that, surely I'm not the only LT95 user in the world who has used engine oil with Britpart thrusts? I'll ping an email to Britpart and see if they have any comment.

Anyway, that's something to try. I'll do the gear contact tests to make sure the input or High Range gear aren't mismatched. If they look ok I'll try gear oil and monitor very carefully for a while.

Thanks for chipping in, looking for any ideas at the moment.

Pete

**Busted Syncro** · 16th April 2016, 05:42 PM

G'day Pete,
All your info noted. OK on Emailing Cradocks as you have excellent pictures of the damaged components to send to them.
My thinking is why not go back to bronze thrusts and GTX oil the way it was designed to be used. The bronze thrusts are kinder to the gears and are meant to wear and be replaced. Steel is going to wear the expensive gears as well.
Also if you need to shim up the bronze thrusts to get the correct end float you can make up steel shims to fit behind the steel backing on the bronze thrusts.
If you go for a GL5 for the transfer it mean you have two types of oil you have to use.
I had the same problem with my series 2a when I fitted a rocky mountain O/D. Had to use a GL4 oil in the transfer box so went for the suggested synthetic Castrol Syntrans 75w/85 GL4 and also use it in the main G/B without any problems. I buy in bulk so only one drum pump required.

Don't you just love Landrovers!!!!!!
Chris

captainslow · 16th April 2016, 08:54 PM

Originally Posted by Busted Syncro

Don't you just love Landrovers!!!!!!

Hehe, yes it will take more than this to dampen the love affair.

I've sent off some info to Britpart (rather than Craddocks) and I'll see if anything comes back. But it does make sense that the oil may be the culprit. The Low Range gear is spinning pretty fast when the High Range gear is selected and it was only the thrust washers each side of the Low Range gear that failed.

Yes, it would be a good experiment to go back to the bronze thrusts. However, I do like the idea of steel thrusts if a higher spec oil will solve the munching - sort of like a poor mans TRB setup

I'll post any responses from Britpart

Pete

**PhilipA** · 17th April 2016, 07:56 AM

This is most probably teaching grandma to suck eggs, but have you checked that the bore of the intermediate shaft is clear of debris?

I recall many years ago stuffing an air line into the intermediate shaft and a great plug of bronze being ejected.

As you probably know the lubrication for the bearings and thrust washers is via oil running into a pocket at the end of the shaft and centrifugal ( on second thought just drip) force ensuring the oil was ejected from the many holes in the shaft. I think logically the holes should point down.
Regards Philip A

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