F5A & F8B Gear Box Identification - solved

MightyBoy tech questions and answers.
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ike849
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Location: Brisbane, Qld

I have 3 what i thought to be F8B g/boxes in my backyard.

It turned out i had 2 f8b gboxs and 1 f5a gbox after i finished counting the teeth on the diff and output shaft.

While doing this i discovered a way to dicern between an f5a and f8b gear box if someone has removed the timing sticker from the top.


How to identify your box;
Under the g/box there is a round plate that covers the shifting mechanism which connects to the shifting forks, which shift the actual cogs. On this plate will either be 671-A or 671-B. Done you now know if you have the f5'A' or f8'B' type...

F5'A' Type
http://www.tamon.org/gallery/v/members/ ... e.jpg.html

F8'B' Type
http://www.tamon.org/gallery/v/members/ ... e.jpg.html


On a side note;
The f5a gear box has a wider bearing for the 4th gear but this CANNOT be placed onto the f8b output shaft as there isn't enough shaft space for it to run.
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eris
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thanks for this. I have a box in the shed , didn't know which one it was but will look thanks again.cris :lol:
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MERCURY
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ike849 wrote:
On a side note;
The f5a gear box has a wider bearing for the 4th gear but this CANNOT be placed onto the f8b output shaft as there isn't enough shaft space for it to run.
So dose this mean that I can't run my F5A box on my F8B engine? (it's out of a hatch)
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Brayden
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Yes you can. Ike was talking about interchanging internals between the two boxes. ;)
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greenzook89
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wouldnt the gear ratios be too short with a F5A box on a F8B motor tho?? We had that problem with my mates one....
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Brayden
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Hell yes. It makes 1st gear almost useless, and forget about cruising on the highway!
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MERCURY
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O.k so yes it will fit, no it's not ideal. I might just rebuild the F8b box.

Thanks :wink:
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Brayden
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Interestingly I have three gearboxes here, none of which have any code marked on the inspection plate. :?

Looks like I will have to pull them apart to see what they are.
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suzutey
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Brayden

Interestingly I have three gearboxes here, none of which have any code marked on the inspection plate.
same :? .
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cam
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could you find out the ratio of say 4th gear by turning the input shaft and counting the turns of the output shaft?? or are the ratios the same?
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scott7
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my boy with F8B engine and F5A box cruises very well at 110 with 13' wheels
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ToranaGuy
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I thought the ratio's are almost the same, but the final drive ratio is different between the gearboxes?

I know it's on these forums somewhere, that info that is.

Cheers

ToranaGuy

Edit: -> Borrowed from Suzukituning.com - all the credit for this info goes to them.

4 speed F8B gearbox gear ratio's:
Gear Gear Ratio Speed Ratio
1 43/12 3,583
2 39/18 2,166
3 32/24 1,333
4 27/30 0,900
Reverse 37/22x22/11 3,363
Final 87/20 4,350

4 speed F5A gearbox gear ratio's:
Gear Gear Ratio Speed Ratio
1 43/12 3,583
2 39/18 2,166
3 33/24 1,375
4 28/30 0,933
Reverse 37/22x22/11 3,363
Final 90/17 5,294
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ToranaGuy
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Got an update for you guys,

I have been in the shed, and the gearbox i thought was a F8b 4speed turns out it's a F5a - after looking under the grease i found the 671-a marking. The other gearbox, which is in 1,000 pieces, has no marking at all, which i thought was a F5a box.

Anyway, i counted the small gear's for each box. The box that has no markings has an F5a diff in it based on the number of teeth, and the box in pieces has the right number of teeth on the diff gears to be the F8b box. I didn't count the rest of the gears, don't have the time atm.

I did find an interesting marking on the crown wheel of the F8b diff, "784", which i have also seen on a fair few F8b cylinder heads. Not sure what it means but i'm thinking it's a code for F8b bits. I didn't pull the F5a diff apart to see what it has written, if anything on the crown wheel.

I also noticed the small gears (pinion?) are different in each box, not just the number of teeth, my F8b pinion gear has a recess on the face of it, the F5a item is flat!

No pics atm, but maybe tomorrow.

Cheers

ToranaGuy
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stevan_istheman
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Interesting..
Might be even more fun if F6A 5 speed parts will fit with the aussie 4 speed components. :|
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Brayden
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stevan_istheman wrote: Might be even more fun if F6A 5 speed parts will fit with the aussie 4 speed components. :|
In what way?
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