Sourcing gears for a 5 speed box

Classic Z

Club Member
Hi

Does anyone know where to buy or even if it is possible to buy gears for the 5 speed original 280z box.

I have removed my gearbox in order to replace seals, clutch etc and noticed that there is wear to the reverse gear. I have been trying to buy a new reverse gear from USA but can't find one.

I was told that it may be possible to have it repaired. Is this likely and does anyone know a machine shop that can do it?

Many thanks
 

jonbills

Membership Secretary
Staff member
Site Administrator
which gearbox is it? fs5w71b? I'm not sure there was just one 280z 5 speed.
If its a 71b, it may share the reverse gear with many 71 gearboxes from later cars.
 

status

Well-Known Forum User
Two boxes for a 280zx,I think two of the ratios are different but can’t remember which ones,people usually go for the later 280zx box as it’s a bit stronger so I reckon reverse is the same
 

Mr.G

Club Member
Two boxes for a 280zx,I think two of the ratios are different but can’t remember which ones,people usually go for the later 280zx box as it’s a bit stronger so I reckon reverse is the same
I remember discussing this with Mike, RIP, i think he said theres an excessive drop in revs between 2nd and 3rd on the early one.
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
What is the problem with your reverse gear? I've ruined a few Datsun boxes by pulling the lever towards me slightly and trying to engage reverse from 3rd instead of pulling the lever straight back to 4th.

Note with early Datsun boxes reverse can be damaged by pulling back from 5th to reverse i.e. 'going for 6th' but on the 280ZX box there is a 'latch' mechanism in the tailshaft that prevents this. Not sure about the 280Z.
 
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status

Well-Known Forum User
Mr G is right and can you use a gear from a knackered old 240/260 box,might be worth a look,if you don’t have any luck let me know exactly Wot you want as my mate rebuilds boxes although he has retired now he might be able to recommend someone,he done my old 280zx box
 

atomman

Club Member
If the reverse gear is the same as the 4 speed item , there was what's left of a 4 speed on ebay the other day and on here I think ? after it was used for a S14 upgrade

if the gear is ok you could get that and strip out the gear to use in yours
 

Albrecht

Well-Known Forum User
Reverse gear cog and counter-gear on the 71B boxes are straight cut (not helical) so are pretty straightforward to Stellite weld and re-shape by hand, but - because it is a reverse gear and gets fairly minimal use - if the damage is only on the tips of the teeth (no synchro on reverse) the sharp bits can be smoothed off, the other teeth ground to match, and the gear saved.
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
Yep, just like mine. The S14 box is a big improvement in many ways and that has synchro on reverse.
 

Classic Z

Club Member
It's not too badly worn. I just wanted to sort it if possible before I put it all back in the car.

Once I did go from 5th to 4th on the dual carageway and it hit reverse. It was one time so not sure if it was that as the car is so old. There were some metal filings on the magnetic plug but I have been told that is normal for an old transmission. Rest looks good. No noise from bearings and all gears changed well.

Here are a couple of pics of the reverse gear.
 

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Rob Gaskin

Treasurer
Staff member
Site Administrator
Yep, it's a design fault - it shouldn't be easy to engage reverse.

I'd 'tidy up' the teeth with a file and clean up the case etc.

I even thought about putting a reverse lock on my car i.e. move a latch to use reverse.

Pic attached is 280Zx box on left, S14 on right.
 

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Ian Patmore

Well-Known Forum User
i think he said theres an excessive drop in revs between 2nd and 3rd on the early one.

There is a drop, but it's not excessive. But if your engine develops a good wide range of torque, 3rd becomes a much more wide ranging use-able gear on the road.
 
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