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Unimog 1300L 1984
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149 Posts
Discussion Starter #1
How much noise is expected when operating the Claas overdrive? I haven't done much driving with mine since fitted, but I notice it is relatively quiet at low rpm (eg 1500), but much more of an audible clash at higher rpm, eg shifting up or down when going up hills at 2000-2300 rpm say. The switch does operate right at the end of clutch travel & I pause long enough for the shift to complete before letting the clutch pedal out.
 

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Sold .....1987 U1250 Unimog
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1,005 Posts
I'm sure others will chim in... but the one in Chris U1700 "which is now in CO somewhere" was pretty smooth and I do not recall it changing any noise or pitch in the Unimog other then the reduction in Engine related RPM.

I wonder if yours is maybe not fully engaged in terms of the gears? As I recall there is an air controlled slave control similar to the PTO clutch, I wonder if there is any adjustment in it.

David
 

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Unimogs 435's
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758 Posts
Defender51 I can put you in contact with someone in Brisbane with a u1250 and a claas overdrive if you want to compare. I could not hear the Claas shifting all that loudly when running the truck down the road. Ben
 

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250GD Wolf
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I can here mine shift, but only if I'm really listening for it, I here the air escape during the change but that's about it. It makes no more noise than that.
 

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'88 U-1300L, '70 406, '78 406, '78 416 project, '82 406, '57 404, '65 404, '70 404, '68 Haflinger.
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I seldom hear any gear noise on mine, either clash at shifting point, or during operation. It matters how you manage engine speed between the time you disengage clutch and engage the switch to force the Claas to shift. There should be enough 'room' between those two events to compensate for gear change by either increasing engine speed or reducing it.

As for lubes, I run Amsoil MTF. It's easily available and works. Just drained my Claas for an oil change after 80k km (about 3 years, reached 100k on odometer!) and there were near zero wear products....no sheen or anything. That's mostly road mileage.

Bob
 

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I have a Werner instead of a Claas but it's probably somewhat similar and the only way I can tell if a shift has happened is by the tach. No noise. Flip the switch the push in the clutch and let it out and the shift happens. If I'm shifting down I match rpms before I let out the clutch.
 

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Unimog 1300L 1984
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149 Posts
Discussion Starter #8
Thanks fellas for your comments. It's good to know the shift should be quiet, as I would have expected it to be. I run a 75W90 GL4/GL5 spec oil in the Claas as well as the main box. That's the first oil I've put in, as I haven't had the vehicle long. I know the cold shifts on the main box are not as easy as whatever the BW used, but I need to cope with higher ambients, and the BW oil I drained looked pretty ordinary.

Coming to work this morning I decided to pause the clutch movement just before the switch was activated, and this seemed to be quiet. At that stage, however, the the oil was up to operating temp, and I was at lower revs. I'll look forward to trying your advice Hammogger this afternoon, as it appears it is at least partly operator error on my part.

I'll also keep the Amsoil MTF in mind.

Does anybody measure the gearbox operating temperature? I haven't had mine on a long trip yet, but it sits at about 63 deg C after 1/2hr drive. All other components are running cool (25 - 42 deg C), by the IR thermometer.

Thanks
 
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