5th gear gate spring

MikeB

MikeB

Well-Known Forum User
Guys

Just got my 240 home, one of the issues on it is the strength it takes to get the lever into the 5th/Reverse plane on the change. I don't think it is a selector issue, it seems to be that the spring that you have to push against is very strong, possibly been up rated at some point to erase the chance of selecting R on a snappy 3 rd to 4th change maybe.

Looking at the Haynes manual I see there is a Plug and plunger at the gear lever end of the change, NR 5 in the pic below

P2240048640x480.jpg


My question is what are the two dark objects between it and the plunger, two springs? Or something else. And secondly could I unscrew the plug with the box still in the car and bits not drop into the nether regions of the box ??



Cheers

Mike
 
Albrect

It's a 5 speed, I realised that the Haynes manual only shows the above view for a 4 speed, but from the other 5 speed I had seen, the selector mechanism with regards to the 5th/ Reverse plane seemed to have a similar spring gate mech. However if it is different if you have any dwgs of what it there, I'd love to see them if you can post.

Having read the Gearbox thread that JK linked above, my problem seems exactly the same, and the hydraulic pressure build up looks a credible theory, certainly once you get it into 5th if you drop down to 4th and then back up to 5th it justs snicks in. But leave it a while and it's hard to get across the gate again


Cheers

Mike
 
So it's a 'B' type 5-speed? OK.

See attached below a scan of the FS5C71-B manual page which shows the tail casing and the reverse plunger & springs, for reference.

It's similar to the 4-speed 'B' type in principle, but subtly different.


I know this might sound silly, but have you taken off the gear lever gaiter and the rubber(s) underneath, and tried it then? I drove a 240Z once which had similar symptoms, and it turned out that the inner rubber seal had collapsed and was fouling the stick against the hole in the trans tunnel. Sounds unlikely, but it wasn't immediately obvious that it was anything other than an internal problem with the transmission.

Worth eliminating that as a possible cause.
 
Albrecht,

Many thanks, that's very helpful. I'll check out the gaiter as well



Cheers

Mike
 
OK, thought I'd best round this thread off for any future member with an issue selecting 5 th gear.

The problem turned out to be a hydraulic lock behind the 5th gear detent plunger, due to the failure of the oil seal on the selector shaft that goes forward into the gearbox. Oil was getting behind the plunger and when you tried to select 5th, the gear lever was hard to move across the gate. If you muscled it in, the oil was pushed out and hence the next couple of shifts into 5th were easy, until after a while the oil built up behind the plunger. I hope that describes it clearly.

So the proper fix would be to replace the oil seal on the selector rod, but unfortunately some gorilla had tightened the selector fork onto the rod and despite my best efforts I couldn't get it off so to withdraw the rod from the back of the rear gearbox cover, to enable removal of the offending seal.

So my solution was to create a way for the oil to escape from behind the plunger. Now you could machine grooves into the side of it, or drill small holes in its face, but using what I have available, I drilled a hole in the end of the retaining plug ( Nr 7 in Albrecht's schematic above) soldered in a bit of brake pipe and the connected a thin plastic hose and ran it round to drian into the breather. So the oil can now drip safely back into the 'box.

Voila, one effort free selection of 5th gear !

Hope that helps any future sufferer :)
 
Last edited by a moderator:
Hi Mike,when i had that car i had 5th gear replaced as it was the same as 4th gear no difference when i changed up,dont know if the box was changed after i sold it,but that gorilla is one of my mates who does know his stuff,i will give him a slap for you when i see him
 
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