Bang

[Silverbake]

'97 Disco 1 V8, gassed and with 2in lift.

A couple of weeks ago, with the help of the forum, I got my sticky diff-lock working, or at least, so I thought. It certainly engages now, and the selector light behaves itself....

BUT, since then, I've had a few interesting, unidentified BANGS coming from down under when on the road. Usually having just turned a sharp corner. Its like a sort of uppercut with a concrete block , somewhere in the suspension/transmission.

First time it happened, I pulled-over and inspected underneath, expecting to find a big lump of metal hanging down and scraping the tarmac. Nothing. After a good check all over, I drove off carefully and all seemed well except my nerves.

No probs for a couple of days, then the same thing again; one big thumping bang.

OK, so there's a problem. I have been doing a fair bit of off-roading, giving both the suspension and the transmission a good work-out. I gave it some uneducated thought, and came up with two possibilities: A misaligned spring re-seating itself, or transmission wind-up releasing itself. This probably demonstrates my high level of ignorance, but hey, I'm just a newbie!

I tried selecting/deselecting diff-lock a few times and all went OK for a couple of days, but then.... you guessed... BANG!

More waggling of selector, more off-roading and more trepidation every time I go round a tight bend, but it's been a week now without so much as a tick.

Could it have been wind-up due to a stuck diff? I don't know what effect that would have, but I do know it wouldn't be good.

Silverbake.

[J@mes]

Sounds like the difflock coming out - its what mine did when it got stuck in!

Every time I use it now I get the bottle jack out and get one wheel up to check weather the D/L has released or not.

takes a few minutes on the road side but its worth it to not damage the transmission i think!

[mickeyw]

Agree with what James said ^^^. I have experienced this too.

Also had similar noises when the crown wheel bolts came loose. When one bolt worked it's way out far enough it was decapitated with a loud bang. I only found this out when the last bolt broke and I lost drive

That said, I still favour the first possibilty, especially as you D/L lever was stuck to begin with.

[freeagent]

^^^^what they said, sounds like its your diff-lock unlocking after the transmission has wound itself up a bit (going round a sharp bend)

[drkwack]

this msy help when my diff lock lever was used for the first time I found that by reversing a little way it was easier to release the diff lock dont know why it worked though, hope this helps.

[landmannnn]

The transfer box is the borg warner chain driven on this isn't it? If so it is jumping sprockets and needs a new chain.

[Silverbake]

The transfer box is the borg warner chain driven on this isn't it? If so it is jumping sprockets and needs a new chain.

I've honestly no idea.... how can I tell? And if it is a Borg Warner, can I replace the chain with the box in-situ?

Silverbake

[maxtherotti]

the borg warner transfer box is auto diff lock (viscous coupling) so as his was stuck i think its the normal variety

rob

[First_Fleet]

But why is it winding up in the first place?

He said it does it on road. That's not normal, unless someone is fiddling with the CDL lever.

From what Silverbake has said, it appears like more investigation is essential, imho.

[J@mes]

Is it happening more than once after the D/L has been taken out? or does it only happen once per time it is being used?

As I said - Handbrake on, jack NSF up and try spinning it after its been in D/L

[q-rover]

Disco's were'nt fitted with the Borg Warner, only RR's.

As far as I am aware all Disco's upto 2003 (before D3) had

the LT230 or variations thereof. (with/ without spigot, etc)

[Silverbake]

Thanks for all your thoughts.

It DOES happen on the road, but this seems logical to me: Off-road, the wheels can spin in mud, etc. without my noticing, and without a bang. On road, as there's more grip, the tension would be constantly building every time I stray off dead-ahead. It would then finally "let-go" when it's had too much, like after going round a tight bend. (this is based on a little bit of logic and a LOAD of ignorance).

It happened more than once on some occasions after I'd used Diff Lock, but as I'm not sure whether or when it finally released (if indeed it was stuck in the first place) its difficult to be sure.

I guess the logical thing to do is to wait for it to happen again (Its still been OK for the past several days), then immediately jack-up a corner to see if it's locked.

I just need confirmation of the logioc I'm using here:

1/ If it is a release of wind-up, am I right to assume the diff would still be locked after a bang (i.e. the release and bang were only a temporary correction and the box is still basically in the same state/setting)?

2/ If I raise just one corner, should it always run free if Diff Lock is NOT engaged?

Finally, a knowledgable mate has suggested it could be worn swing-arm bushes. I've had a good furtle about all the linkages but can't find any play. Is this a red-herring?

Silverbake.

[J@mes]

2/ YES.

not sure on the other questions!

[Silverbake]

The Phantom Blacksmith is back, banging away under the floor, twice this week so far.

Nothing mentioned so far seems to fit the symptoms, so I'll try to be more specific:

It happens:

When driving on tarmac, often but not always after going round a bend. Never so far at high speeds (but then I commute into Birmingham, so that's no surprise)

It sounds like:

A single, hefty bang, under the cab floor, which I can feel through the pedals and is sufficiently dramatic to make any unsuspecting passenger jump.

Afterwards:

...... nothing..... just keeps on driving in an orderly manner.

Ideas so far:

Transmission wind-up

Bushes worn

Springs re-seating

New Thoughts:

Broken half-shaft (do discos have them?)

LPG leak causing minor explosion

Some bas**rd leaving a banger up my exhaust

A Ninja hit-man trying to shoot me from under a man-hole cover

Does this seem to be getting a little over-imaginative? Well OK, so what do you think it could be?

No doubt I'll find-out one sunny day just as I'm off on some essential, life-saving trip to collect a jar of organic pesto for the Iron maiden, and whatever it is finally explodes in a dramatic and terminal burst of teeth and splines and shafts.

HELP!!!!

Silverbake.

[ashtray]

with diff lock on, jack up one wheel. it should rotate about 1/4 turn(ish) if it is free to rotate then something is broken. and yes disco's do have half shafts. if it gets stuck in difflock then a halfshaft would have snapped when driving on the road. When disengaging diff lock, do it whilst still off road, reversing slowly and turning helps.

[BogMonster]

Something nasty happening in the centre diff causing it to jam up and then release with a bang would be my guess, though I've never heard of anything exactly like it, sounds very odd

[Silverbake]

with diff lock on, jack up one wheel. it should rotate about 1/4 turn(ish) if it is free to rotate then something is broken. and yes disco's do have half shafts. if it gets stuck in difflock then a halfshaft would have snapped when driving on the road. When disengaging diff lock, do it whilst still off road, reversing slowly and turning helps.

Thanks Ashtray.

After my previous post, things got worse with 3 bangs within 5 miles. The diff-lock selector lever began to gently rumble and vibrate, so I pulled into a long lay-by and tried selecting/deselecting high/low, lock/unlock in forward and reverse whilst crawling backwards and forwards. Stupidly, I didn't have my jack on board, so I couldn't test properly. Eventually things seemed to free-up and I crawled home. No rumbling, but the lever was gently vibrating. I can't remember whether it used to do this before the problem started, but I don't think so!

Home is on a steep slope every way you turn, so no jacking possible. I loaded up the jack and found a nice, quiet spot to follow your instructions.

I then tried what you suggested and everything seemed to work OK, though at first I'd left the box in "Park" and nothing would move! Did I mention the box is auto. and would this make a difference?.

The wheels (I tried nearside and offside separately incase one half-shaft was bust) ran just as you said they should, though I wouldn't exactly describe the movement as "free". There's gentle but persistant resistance and no way you could spin the wheel to run freely on its own. I guess this is just due to the friction in the diff?

Since then, things feel better, but I'm still on high alert. I'll post again after a few days, or any change. Due to go off-road tomorrow..................

I've been trying to educate myself about how a diff works, and found this:

Brilliantly simple for a newbie to grasp!

Silverbake.