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Odd Ferret trans noise...


njjeeper

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Not sure if anyone has had a gearbox apart enough to assist but I am hopeful! Sitting in the ferret, engine running, forward/reverse lever in Neutral. With the level in neutral, I can select first, and engage and is quiet. Same for second gear. When I engage 3rd gear there is a rattle sound from the transmission. In 4th the rattle is much louder and in 5th its quite loud. Sounds like a metal bolt being shaken in a tin can. Its very repeatable and is never present in 1st or 2nd. Only begins to make noise in 3rd and then gets much worse in 4th and worst of all in 5th.

 

I heard the same noise when in gear going down the road but thought it was normal. Since it makes the noise with the ferret stionary, I am concerned its something in the gearbox. Anyone know what could cause a noise like this that is so gear specific?

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Well, with the fwd/rev lever in Neutral that disengages the trans from the road wheels and should isolate the gearbox. I have never had the trans apart and it doesn't look like its been torn into before.

 

With either of the first 2 gears engaged, but the lever in Neutral there is no noise at any rpm. When the noise starts in 3rd/4th/5th gear, the sound doesn't change with RPM either. It's just a consistent rattle that is louder as the gears go up. I was hoping for someone with teardown experience to tell me what could be different about the 1/2 gears vs the 3/4/5 gears inside the transmission. Perhaps they ride on a different shaft, etc.

 

I cant imagine sourcing a transmission in the US is going to be fun :)

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Well,

 

if you haven't been tinkering then that answer that one.

 

Have you been doing the "pedal up" procedure?

 

What manuals do you have to look at? I am suspicious as to what you have judging by your questions.

 

What is your skill level and shop equipment available.

 

I am in the process of acquiring some gearboxes as spares for rebuilding, I have had mine rebuilt locally but that is all long term, you want here and now fix.

 

The gearbox is relatively simple but it seems light years ago that mine was rebuilt and the vehicle rebuild has stalled owing to building a shop.

 

There is a lot inside but it is a drum and brake bands and gears inside. The photo shows one apart, mine, a lot can rattle.

 

Give us some answers, sounds like gear specific problem.

Ferret gearbox bands and gears clean.jpg

Ferret gearbox brake drums out.jpg

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Well, for tools and skills I think I am am up to the task but who knows for sure. This Ferret was someone else's stalled project and I built it from an empty hull and about 30 bins of parts using only the manuals and the internet. That being said, the inside of the gearbox, while very well explained in the manuals is quite complex. The Ferret runs and drives normally. Brake bands in the trans are all below the surface of the adjusters. Oil levels look good and it doesnt get hot when run. Just that pesky noise. I think if I had a spare unit to take apart I could figure it out but I'm nervous to tear into the only one I have. Hence, why I am hoping to find some sage advice from folks who have been inside one of these things. That, or find someone with a spare take out they want to sell.

 

From your pics, it looks like you have had one apart. Can you think of any parts that would turn in the higher gears that would not in the lower 2?

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I think Mikethebike is on the right track. You said earlier that the noise does not change with RPM. If you mean that the noise does not get faster/higher pitched as engine RPM increase, but just louder as you change up each gear, then it can not be inside the mechanism of the gearbox as anything there would change with RPM and not make the 'bolt in a tin can' noise that you describe - certainly not for long! However if there were an object loose in the gearbox (or transfer box as there are parts turning there when in F/R neutral) that object could be catching on something moving and being thrown against the case, taking a fixed time to fall back so not being RPM related. However it is hard to see how this could be gear dependent. Back to the gear linkage outside the box.

 

Good luck, David

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So I tend to agree that it is quite possibly outside the box for the stated reasons.

 

You didn't answer the "pedal up" question.

 

It wouldn't be the first time someone has put a ferret together and had something rubbing or perish the thought left a tool behind that sits and rattles only at certain speeds, I know I have done that twice, I am human.

 

I am not a mechanic but very logical, start by removing interior tin work and slowly strip it down and each time repeat the gears and see if it has gone. Are you running it up in those gears on the road or on a rolling road or axle stands?

 

There can always be interference between rotating prop shafts and objects.

 

Go slowly and you will find it.

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Ok, did some homework last night in the 30 degree weather :)

 

As for pedal up procedure, yes, been done many many times. Noise is def inside the trans as I removed the tins and such for testing.

 

What I found last night was the noise has to do with, i think, the output shaft speed of the gear box. I didn't hear it in gears 1 or 2 and started to notice it in 3. What I found last night was that the noise is there in 1 and 2. I just had to rev the engine really high to get the trans turning fast enough in that low gear to make the noise. In 5th the output shaft of the trans is turning at engine speed and that's where its the loudest. Also, if I engage 5th and then go to Neutral, the noise persists. The only way to stop the noise is to go into first or second at low RPM and slow the output shaft down.

 

Also, after the trans warmed up the noise changed a bit. Much less of a bolt in a can and just more of a LOUD gear type noise. Kind of like a bad water pump bearing almost. In 5th gear, revving the engine the noise is really obnoxious. Doesn't change in pitch or anything, just gets louder.

 

So, based on these new findings, is it possible that I just don't know what straight cut gears turning at high speed should sound like 2 feet from my head? Is it possible I need to flush and refresh the gear oil? Could I have bearing that crapped on the output side of the trans?

 

Thanks for the assist everyone. I know its a winding road but hopefully the journey is worth it :)

 

Here is the Ferret at Veterans Day here in the US :)

ApplbeeFerret.jpg

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Hi

 

Just a thought, can you change gears easily with no ‘kickback’. I seem to recall (one of the Ferrets I occasionally work on) there was some odd noises which went away when after the preselect bands in the gear box were correctly set up, these can wear over a period. The procedure to do this is in the manual.

 

Also when the engine was taken out (a long time ago) we found odd spanners, spare nuts and bolts, and some coins. As noted if you have anything in the floorpan, items like this may well have moved and are now rattling around, the noise level/tone will change with the gear selected and engine speed.

 

Also as noted drain the oil and look for any debris (hopefully you don’t find any). If you find loads of bits, I wouldn’t run it in case you do any further damage

 

Good luck

Richard

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If anyone is in thier Ferret over the next few days, it would be great to hear someone else test like I am and see if they hear a difference from 1st to 5th. Just put the fwd/rev level in neutral and engage the gears from 1 to 5. Is 1 more quiet than 5?

 

I took all the tins off and changed the older oil out for fresh which did quiet things down a bit. Knowing what somebody else is hearing may help me me decide if I am hearing a bad bearing or straigh cut gears....

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Mine rattles and carries on much like what you described with the transfer case in neutral, it also howls a bit on the overrun. It's probably a bearing that is on its way out, but I've done over 1500km with no real problems, so it can't be too serious.

 

Cheers,

Terry

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Mine rattles and carries on much like what you described with the transfer case in neutral, it also howls a bit on the overrun. It's probably a bearing that is on its way out, but I've done over 1500km with no real problems, so it can't be too serious.

 

Cheers,

Terry

 

Hi Terry,

Credit to you for driving for something like 500 miles to Corowa last week in your Ferret, especially considering the temperature. Good to catch up with you again.

 

cheers Richard

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Good catching up with you too, Richard. I had a great time at Corowa. The trucking company dropped off the Ferret back in Adelaide this afternoon, as I wasn't (quite) crazy enough to drive it back :)

 

Cheers,

Terry

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