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Mu: 3.1 gearbox to replace bust 2.8 box. can it be done?

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Mu: 3.1 gearbox to replace bust 2.8 box. can it be done?

Postby mumanbeing » Sat Jul 17, 2021 6:35 pm

G'day. So my project 2.8 Mu (manual transmission) needs a new(ish) gearbox. A box of beer can buy me a mates gearbox off his 3.1 manual transmission Mu. (parts donor now sadly...) Can anyone please advise on the feasability of this plan? Haven't had any luck chasing down a gearbox yet, and the 3.1 potential replacement is in good condition.

Cheers for any advice, take care out there.
mumanbeing
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Re: Mu: 3.1 gearbox to replace bust 2.8 box. can it be done?

Postby geeves » Sun Jul 18, 2021 6:59 am

Simple way is get his driveshaft as well. 2.8 has a spline at the back the 3.1 a flange. Otherwise its just a few dozen bolts and 150kg of gearbox. You can swap the outputs over but the driveshaft is easier
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Mu: 3.1 gearbox to replace bust 2.8 box. can it be done?

Postby mumanbeing » Sun Jul 18, 2021 1:19 pm

Sweet merciful crackers. Muchly appreciated Geeves. Forgive my (low grade) mechanical knowledge, but then the 3.1 driveshaft slots into the rear axle dif? I'm interpreting that to mean the driveshaft spline meets driveshaft flange, which is connected to dif?

(Dif being the bigmetal lump the transfers power from the driveshaft to the rear axle?) I dont have to strip off the dif & rear axel bizzo? No extra shenanigans asides from that? Sounds fairly straightforward.

Might mean two boxes of beer...

and another box of beer for you when I'm next in Welly/Rangiora.

Cheers heaps :D
mumanbeing
Isuzu Baby
 
Posts: 17
Joined: Sat Jul 17, 2021 2:39 pm
Location: Dunedin
Age: 38
Country: New Zealand
City: Dunedin
Vehicle: 1990 Isuzu Mu 4jb1 turbo
Intercooler/scoop modification
Snorkel, custom bar work, spotlights
Much love needed

Re: Mu: 3.1 gearbox to replace bust 2.8 box. can it be done?

Postby geeves » Sun Jul 18, 2021 3:56 pm

ok driveshaft has a flange at the diff end on nearly all 4wds. Gearbox end though the 2.8 had a spline on the driveshaft which slides into the gearbox. On the 3.1 the output of the gearbox is a flange and the driveshaft has a matching flange
Sanding your knuckles before starting work can help. That way you cant skin them
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geeves
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2004 Honda CRV

Re: Mu: 3.1 gearbox to replace bust 2.8 box. can it be done?

Postby mumanbeing » Tue Jul 20, 2021 3:28 pm

Gratitude for clarifying, where there's a will (and a skilled, trustworthy mechanic....) There's a way. Will be yarning to my guy tomorrow to see if he's keen.
mumanbeing
Isuzu Baby
 
Posts: 17
Joined: Sat Jul 17, 2021 2:39 pm
Location: Dunedin
Age: 38
Country: New Zealand
City: Dunedin
Vehicle: 1990 Isuzu Mu 4jb1 turbo
Intercooler/scoop modification
Snorkel, custom bar work, spotlights
Much love needed


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