Loud Bang When Shifting Gears in 95' Disco V8

GreekDisco1 · Aug 10, 2024

Hello everyone!

I have a 1995 Discovery with a 3.9 engine that my father has owned since 1996. I grew up in this car and have many fond memories, so we've decided to restore it to its former glory.

Over the past two years, we've been diving into the full Land Rover experience to fix it up. Unfortunately, despite our efforts, we've run into new problems caused by mechanics who, instead of resolving issues, have created new ones.

The main problem we're facing now is a loud bang when shifting from Neutral to Reverse, and it's even louder when shifting to Drive. We've already replaced the front and rear trailing arm bushes, but the issue persists. I'll upload a video where you can hear the noise.

If anyone has any insights or experience with this issue, your help would be greatly appreciated!

The link attached is the video of the loud sound, Posted on reddit because i dont know how to do so in landyzone. Thank you!!

Firebobby1 · Aug 10, 2024

Have a look at how much play you have in the prop shafts, could be a UJ going

Stanleysteamer · Aug 10, 2024

Or play in the pinion drive(s).

GreekDisco1 · Aug 11, 2024

Forgot to mention, that when i turn on the engine in the morning and its cool most of the times it doesn't make any noise at all. Does this info ring any bells why I have this issue?

Stanleysteamer · Aug 11, 2024

GreekDisco1 said:
Forgot to mention, that when i turn on the engine in the morning and its cool most of the times it doesn't make any noise at all. Does this info ring any bells why I have this issue?

When oil or ATF is cool it is thicker so less likely to allow banging to happen.
May I suggest you check the transmission fluid level in the gearbox?
It'll be in the Haynes manual or on RAVE.
It could simply be that you don't have enough in there, or that it is old and has gone thin. To say nothing of the state of the filter if there is one on a V8.
My own personal Disco 2 auto is a TD5 so not sure if the boxes are the same or similar or whatever.

GreekDisco1 · Aug 11, 2024

Stanleysteamer said:
When oil or ATF is cool it is thicker so less likely to allow banging to happen.
May I suggest you check the transmission fluid level in the gearbox?
It'll be in the Haynes manual or on RAVE.
It could simply be that you don't have enough in there, or that it is old and has gone thin. To say nothing of the state of the filter if there is one on a V8.
My own personal Disco 2 auto is a TD5 so not sure if the boxes are the same or similar or whatever.

First of all thank you for the replies! I have a V8 3.9 Auto, the problem is that i live in Greece and most mechanics either don't know either fix sth and break sth else. I have changed the trans oil and replaced the trans filter but the problem insist. I don't have any mechanical knowledge, but from what you say is there the possibility of trans overheating or cooling issues. And perhaps thats the reason why it makes them when hot. One mechanic said that problem cant be fixed and another said that there are "gaps" (don't know if i translate correctly) in both diffs and in the transfer.

Rangieman123 · Aug 11, 2024

Is the engine idling at the correct speed?
If the idle is too high it will amplify any "slop" in the drivetrain when you select gear.
Does it make the bang if you select D or R with the hand brake on? With hand brake on, youre removing sny slop in the props and axles.

Stanleysteamer · Aug 11, 2024

GreekDisco1 said:
First of all thank you for the replies! I have a V8 3.9 Auto, the problem is that i live in Greece and most mechanics either don't know either fix sth and break sth else. I have changed the trans oil and replaced the trans filter but the problem insist. I don't have any mechanical knowledge, but from what you say is there the possibility of trans overheating or cooling issues. And perhaps thats the reason why it makes them when hot. One mechanic said that problem cant be fixed and another said that there are "gaps" (don't know if i translate correctly) in both diffs and in the transfer.

I think that if the transmission oil overheats there should be a warning light. I know I have one on mine because the sender unit went wrong and I had to change it.
The "play in the pinion drives" that I mentioned is what the mechanic meant by the gaps in the diffs. But as for the transfer box, I don't know.
You can test for play in the differential by taking the propshaft off and turning the pinion drive flange, you should get a bit of play before it makes the wheels move. (support the axle and put the gearbox in neutral. To be safe, chock the other wheels on the other axle.)
I did once have the drive pinion nut become loose and this led to a lot of play and vibration as well. But you haven't mentioned that. This was on the rear axle of a Disco 1.

My rear diff is a bit "loose" and apparently it was a recall issue and mine didn't get recalled. The axle is not the one that came with the car. It is a secondhand replacement that I had fitted when the original axle casing got bent in an accident.
To reduce the "clunk" on taking up drive, I take my foot off the brakes and simply allow the gearbox to select the gear and allow me to move off. It only happens when leaving from standstill, I don't put my foot on the accelerator until it is moving.
The clunk is so slight no one else can feel it.

GreekDisco1 · Aug 11, 2024

Rangieman123 said:
Is the engine idling at the correct speed?
If the idle is too high it will amplify any "slop" in the drivetrain when you select gear.
Does it make the bang if you select D or R with the hand brake on? With hand brake on, youre removing sny slop in the props and axles.

Stanleysteamer said:
I think that if the transmission oil overheats there should be a warning light. I know I have one on mine because the sender unit went wrong and I had to change it.
The "play in the pinion drives" that I mentioned is what the mechanic meant by the gaps in the diffs. But as for the transfer box, I don't know.
You can test for play in the differential by taking the propshaft off and turning the pinion drive flange, you should get a bit of play before it makes the wheels move. (support the axle and put the gearbox in neutral. To be safe, chock the other wheels on the other axle.)
I did once have the drive pinion nut become loose and this led to a lot of play and vibration as well. But you haven't mentioned that. This was on the rear axle of a Disco 1.

My rear diff is a bit "loose" and apparently it was a recall issue and mine didn't get recalled. The axle is not the one that came with the car. It is a secondhand replacement that I had fitted when the original axle casing got bent in an accident.
To reduce the "clunk" on taking up drive, I take my foot off the brakes and simply allow the gearbox to select the gear and allow me to move off. It only happens when leaving from standstill, I don't put my foot on the accelerator until it is moving.
The clunk is so slight no one else can feel it.

Hello!
Thank you for the support!

Rangieman123, Tried that (as you can see on the vid below) and its the same with and without the brakes on, BUT i noticed that always the first change to R does not make the sound (not when its cold as previously said).

Stanleysteamer, thank you will do!

I got under the car and captured two videos testing the driveshaft. Please check them and give me feedback, i can tell that sth is totally wrong but I have no mechanical understanding.

Loud Bang When Shifting Gears in 95' Disco V8

GreekDisco1

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Firebobby1

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GreekDisco1

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Stanleysteamer

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Rangieman123

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GreekDisco1

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