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Knock in drivetrain on up shift 105 GX 1FZ FE

AfricaInHD

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Hello all

I have just purchased a 105 GX EFI. I have a few niggles to sort out and will get to them slowly but surely.
I have been through this forum and others trying to find some more information on what could be my issue. I have read threads from older Prado's and a very interesting one by @Shayne and his issues with a knock in his drivetrain.

Mine occurs when upshifting and accelerating. it is when the vehicle shifts into the next gear that it does it. on down shifts this knocking sound is not there. Only on upshifts. If you slow the shift down there is no sound and it is smooth. The sound is like a big rubber mallet striking the chassis and you can feel it in the vehicle. Today after reading threads over and over again I though I would lock the center diff and go through the gears. Well, the sound DISAPPEARS completely. Perfectly smooth changes!

Before this discovery today I really thought and was hoping it was something to do with the clutch as it happened only as the gearbox was going into gear on a quicker shift. Now after my tests with the center diff locked, i am back to square one!

Any inputs would be highly appreciated.
 

SteveJB

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Though I drive a 100 auto have had this same issue but only when cold so have modified my driving to gentle acceleration for a few minutes for oil to move around and so far all good the box seems not to make the noise after being parked up for a three hour dog walk just overnight you did not say if parked overnight or when on short stop start journeys on my next service am going to put in some Lucas Oil transmission fix maybe some members have used similar products with either good or bad results and can advise on their results also have you greased up all the UJs and the sliding joints and checked for play in all moving parts Eliminate before you Payout
 

AfricaInHD

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Unfortunately mine happens whether the box is cold, warm, hot, rested. It’s as the vehicle goes into the next gear on a normal speed shift. There is a slight bit of play in the drive train but my thud happens while clutch is still depressed. Take a slower shift and no thud. So then in my mind I’d go clutch issue or syncro. However, locking the central diff eliminates all horrible noise completely. So then does that go straight to it being an issue in the transfer case? And if that is the case why does a slower shift also go smoothly?

the joys!
 

AfricaInHD

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So I was under the vehicle again this early this morning.
What I have found with the vehicle in neutral with the handbrake up is that there is a bit of movement in the drive train, more so in the front diff than the rear. Expected wear at 267000kms. When driving you can here that drivetrain lash taking up the slack etc. I’m pretty convinced I’ve got that noise sorted and know what’s causing it (wear in the diffs).

Now I have also parked the vehicle in neutral, transfer in neutral, Centre diff locked. I have rotated the props in opposite directions to each other. There is play of about 8mm. That doesn’t seem too bad or out of the ordinary or am I wrong?

The main issue that I have found is at the rear of the transfer case. There is sideways play in the output bearing of around 2mm. The front output bearing is solid however there is a leak on the seal .

So with the play in the rear bearing I can imagine a knock being prevalent, what I’m trying to understand are two things:
1) would that cause a knock as the gearbox is shifting into a higher gear, as the gearbox goes into the gear, clutch still depressed.
2) with the Centre diff locked, would it being locked support the rear output bearing enough that it would get rid of the knock on gearshift completely, ie, allow no movement in the internals of the transfer case or on the rear drive shaft?

Once again any input would be much appreciated?
 

Shayne

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My 90 series rubber hammer is in the transfer box and unlikely to relate to your 105 .

Dare i say while knowing nothing about 105's that at 267000kms might it just be a combined consequence of general wear on bushes etc , 8mm here and 6mm there all adds up .

I feel my own full time 4x4 Toyota's all get a little more power to the front wheels so perhaps that tiny interval between the rear wheels catching up with the front wheels might cause your thump ?
 

Grimbo

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Sideways play of 2mm on an output shaft needs looking at asap .... if the gears are a helical cut then one way will force gears together...the other way with negative torque they will be forced apart ...upshift will load one way down shift the other...
Sort your known issue with the play and see what happens to the thump then
 
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AfricaInHD

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My 90 series rubber hammer is in the transfer box and unlikely to relate to your 105 .

Dare i say while knowing nothing about 105's that at 267000kms might it just be a combined consequence of general wear on bushes etc , 8mm here and 6mm there all adds up .

I feel my own full time 4x4 Toyota's all get a little more power to the front wheels so perhaps that tiny interval between the rear wheels catching up with the front wheels might cause your thump ?

Thanks for the response Shayne. I must agree with a 8mm here and 6mm there. I can definitely feel the slack in those up of power, release of clutch, more so in the rear diff.

Even though the transfer box’s are completely different in terms of design it was really interesting reading your thread and forming the picture of what was happening.

And I think Grimbo has hit the mail on the head and I wanted to see how much of an effect the 2mm sideways play on rear output bearing had, the interesting part for me was how that noise, of selecting a gear even with the clutch depressed disappears completely with the Centre diff being locked.
I’ve grown up around land cruisers old and new, all part time 4wd, and have never heard or experienced this knock as the vehicle goes into gear with clutch still depressed. The take up of power upon release of clutch, I’ve experienced a lot on the older vehicles and in my 5 years of Land Rover ownership that I put myself through

Once again thanks for the input. I’ve now got to work out my best way forward in terms of the transfer case. Bearing and oil seal replacement, which will cause a tear or two, or a full rebuild which would cause at least 4 tears , maybe 5
 

AfricaInHD

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Hi Grimbo

Thanks for the response. As mentioned above in my response to Shayne, my experience on the full time 4wd transfer cases is rather limited.

And I must agree with you in terms of a place to start would be that play on the output bearing. It’s then working out the best way forward, with it out do you do a full rebuild, many tears, bearing change and oils seals. Just a few tears.

The part that really had me was the disappearing of the noise upon lock of Centre diff.

Drivetrain lash I expected and new was there upon purchase of the vehicle in terms of general wear and was always something I would get to. It was this noise of the gear being selected that had me. And then all fine upon Centre diff lock up or a slow shift, like a necessary change on a Land Rover Lt77 box

Well thanks for the input and best to get at it and work our prices and how much of my kidney I need to sell
 

SteveJB

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Spinal Fluid prices are going through the roof at the moment and leave no scar and the by product of tears with no extraction fees
 
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