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'84 Four speed into a '74 three speed & diff ratios

Tech Talk for Cruiser owners.

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Posts: 1143
Joined: Thu May 13, 2004 5:27 pm
Location: Quirindi, NSW

'84 Four speed into a '74 three speed & diff ratios

Post by bushy555 »

All,

Just been searching google trying to find info but cant find exactly what I'm after, so thought that some guru's here might be able to help.

Next door neighbour has a 1974 6 cyl petrol BJ40 three speed short wheel base. Both the gearbox and the rear diff is in need of a rebuild, however rather than doing this he has gone and bought a 1984 6 cyl petrol four speed ute.

Before going adventuring and dropping the box and the diff
My two questions are:
1) Does the four speed have the same bolt pattern, and will it bolt straight in? Or does it require an adapter?

2) Does the diff in the '84 petrol ute have the same ratio as that as the '74 shortie?


cheers for any info
dave
Posts: 1143
Joined: Thu May 13, 2004 5:27 pm
Location: Quirindi, NSW

Post by bushy555 »

Andrew on cool_aus yahoogroups list replied to my posting for anyone who may happen to come across this thread in years to come (after doing a search etc)...


Dave
The box will bolt up to the motor....there isnt anything different in the bell...however the gearbox crossmember might need work. The transfer is better on later model, the tailshafts might need mods, the flanges will be different old to new rear diff...the ratio will have to be checked on the front....u might be lucky and get thesame ratio...if not have him swap the front over aswell as it will be disc brake. Also the shorty handbrake might be on the diff where the ute is on the transfer....so that might need retroing aswell.
Andrew
Posts: 552
Joined: Mon May 26, 2003 2:47 pm
Location: across the pond

Post by beanz2 »

Hmm, there is a bit of confusing info here. A BJ40 has a four cylinder 3.0L diesel. If it is a petrol it is an FJ40. The petrol gearbox will not suit the diesel.

Now, if the 1974 40 series is indeed an FJ40, the gearbox from a 1984 petrol ute will bolt up to the engine, but the mounts are different. The 1974 has mounts on both sides of the bellhousing to support the gearbox and transfer, the 1984 gearbox mounts to a crossmember that runs underneath it. One can take bolt the 1984 gearbox to the older bellhousing but the later gearbox and transfer combination is quite long and is really designed to be supported underneath the gearbox extension. A better approach would be to get the bellhousing and crossmember from the 1984 donor and use it in the 1974.

But the burning question I have is, if your neighbour is keeping the ute, why are you thinking of using its gearbox for the 1974? :lol:

Dave
Posts: 1143
Joined: Thu May 13, 2004 5:27 pm
Location: Quirindi, NSW

Post by bushy555 »

beanz2 wrote:Hmm, there is a bit of confusing info here. A BJ40 has a four cylinder 3.0L diesel. If it is a petrol it is an FJ40. The petrol gearbox will not suit the diesel.
*snip*
beanz2 wrote: But the burning question I have is, if your neighbour is keeping the ute, why are you thinking of using its gearbox for the 1974? :lol:

Dave
Yep, I really stuffed that posting up eh?
Delete every reference to BJ40 in my original posting.

Yep, can understand where your coming from - from your burning question. The cab of the ute is completely buggered, but the 74 is still sweet. It is only the gearbox and the rear diff in the 74 that really just needs a rebuild, but he wants to do it on the cheap (read $0.00) and would rather do the swap (and be hoping that the box and diff are good), than do a full on complete rebuild on them.


Cheers heaps for the info.
dave
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