Mt75 is it a weak gearbox

[Bruce e]

Trying to find source of drive line noise. Driving around some hills the noise is worse in 4th, talking to a mate he suggested the mt75 was at its limit in a 7m motorhome. It's done 250,000 km I have 2 recond gearboxes so may have to do a swap

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[MinorMatt]

No its not a weak gearbox.

The transit variant is designed to lug 5500kg around all day If its whining its probably got oil issues?

[Bruce e]

Changed the oil the old stuff didn't look to bad I am running my mt75s on a 80w tractor gearbox oil and is working well in my other mt75s. I have just got this motorhome and have done a 1200km trip and the noise is getting worse so looks like a reco box. Thanks for the comment Mat

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[V184]

The MT75 uses a specific oil

[Bruce e]

Very hard to get in NZ ,gearbox noise there when I bought it and have a reconditioned gearbox that came out of a similar size motorhome

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[sportscott]

Very hard to get in NZ ,gearbox noise there when I bought it and have a reconditioned gearbox that came out of a similar size motorhome

You should be able to get Fuchs Sintofluid 75w in NZ https://www.fuchs.com/au/en/product-search-aus-nz/

[Bruce e]

Thanks will try and get some

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[Bruce e]

Finally got some Fuchs sintofluid 75w but still noisy but could be shifting nicer will have to do gearbox swap

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[Bruce e]

I have discovered the problem both pinion bearings are worn in a way I have not seen in a bearing previously, I wonder if they have been to tight from the factory they are NTN bearings the crown wheel bearings are fine and wheel bearings

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[bruce.edlin3001]

The noise won't go away ,the gearbox died on a trip south last150 km in 4th as 5th noisey. Put in a good reco box form one I was wrecking the noise exactly the same. Then I remembered that I had used the gear leaver with rubber etc from the old gear box. Put in the leavier form that box and the noise went away. Did a 500km trip no problems then for no apparent reasons it starts again, any suggestions you can make the noise go away by manipulating the throttle?


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