My car occasionally jumps out of 5th gear to neutral. It only happens when decelerating, it never happens when accelerating or at a constant speed. It does this at motorway speeds. There is no bad noises from the box and the gears are engaged properly.

It could be a worn syncro/selctor in 5th, but before you start having the box rebuilt, check the linkages which connect the gear selector to the gearbox.

Thanks. Yes, i have read while searching for an answer on this that 5th syncro may be a problem. Certain days on the same journey the gear does not jump. Long journey will cause the problem more easily. Also when it happens the gear lever moves more when I decelerate which forces the gear to jump out. Are these definite signs of weak synchro? Will an oil change help?

I know this is an old thread, but now this exact gearbox has become much worse. Now I cannot put it into 5th gear and if I do it will pop out very easily. Also I can hear some rattling noise from the gearbox (or maybe clutch). Before I swap the box for another one I want to have a go at the 5th syncho. I want to know where can I get spare parts so I can try to replace the synchro myself.

never been able to find anywhere to actively advertises they sell gearbox innards spares.. best bet would prob be to ask a local place that does rebuilds.. Might even ask them how much to rebuild the box for you cause i have heard of people not paying huge amounts and having all synchros and bearing etc replaced. From videos I have watched on youtube it seems alot of places receive a rebuild kit rather than ordering specific parts... Yes it will defo cost more than a 2nd hand replacement but if its not too much more then worth considering. If i recall correctly my mate was quoted £130 for a rebuild of a GT box and a 2nd hand one was minimum £90-100

dumbledore said:

Thanks. Yes, i have read while searching for an answer on this that 5th syncro may be a problem. Certain days on the same journey the gear does not jump. Long journey will cause the problem more easily. Also when it happens the gear lever moves more when I decelerate which forces the gear to jump out. Are these definite signs of weak synchro? Will an oil change help?

Click to expand...

:idea:Cheap'ish to replace the engine / gearbox mounts,
IF that's part of the issue,
the jumping out is reputed to be a synchro issue..(a test I did on my Regata @1993)

but the lever moving points to the whole gearbox moving in relation to the floorpan

Charlie

Yes, until I decide what to do I am only driving the car locally, no motorways no much need of 5th gear. At the moment I can hear some rattling from the gearbox but not always and with varying loudness. The noise will go away when I press the clutch, but not instantly 2-3 seconds delay. I guess this are rotating parts in the gearbox that don't stop straight away when clutch pressed. This noise got to be related to 5th gear assembly but can't figure what exactly makes the noise.
Do you guys believe that this box will survive driving like this or will it go with a bang any time soon?

Toying with the idea of going for a replacement gearbox. I cannot normally get MK1 one so I am opting for MK2 ones. The question I have is that last time I replaced my MK1 with a MK2 box I had to transfer the MK1 selector over to the doner box and wondering if my 5th gear failure may be caused by a faulty selector and not the 5th gear syncro. Is the selector known to fail? I could possible rebuild the mk1 selector with the parts from the mk2 doner selector. I assume this may be possible as the box is same appart of the selector. What you guys think?

dumbledore said:

Toying with the idea of going for a replacement gearbox. I cannot normally get MK1 one so I am opting for MK2 ones. The question I have is that last time I replaced my MK1 with a MK2 box I had to transfer the MK1 selector over to the doner box and wondering if my 5th gear failure may be caused by a faulty selector and not the 5th gear syncro. Is the selector known to fail? I could possible rebuild the mk1 selector with the parts from the mk2 doner selector. I assume this may be possible as the box is same appart of the selector. What you guys think?

Click to expand...

Here's a mk1 gearbox on eBay.

Didge3 said:

Here's a mk1 gearbox on eBay.

Click to expand...

Thanks, this is good choice, but is from a sx75 and not a sx60 like mine so may be not the same ratios, also I could buy a younger mk2 box for less money. However, if the selector is the problem in my case then this will be my best option at the moment.

I have jut put a Mk2 in my Mk1, the selectors seem to be the same just a slightly different way of shifting, rod V cable. The Mk2 will fit the Mk 1 but not Vice versa due to u shaped mounting bracket. Holes are not on the Mk 1 box for the bracket. I doubt that the problem is anything to do with the selector mechanism.

dumbledore said:

Thanks, this is good choice, but is from a sx75 and not a sx60 like mine so may be not the same ratios, also I could buy a younger mk2 box for less money. However, if the selector is the problem in my case then this will be my best option at the moment.

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60 & 75's share the same ratio's

I believe mk2 boxes have a longer final drive.

EDIT: Nope never mind, just checked and the 75 has a different final drive to the 60 box too. Assuming the diff on your current gearbox is fine however you could swap it onto the 75 box and you'd get the same gearing.

I believe I know what was causing the jump out of 5th gear.
I replaced the gearbox with another one I got from ebay and everything is ok now. All gears are usable and there is no jump out from 5th.

I decided to do a post mortem on my old gearbox and removed the 5th gear cover housing. There instead of seeing a damaged synchro I seen immediately that the two nuts bolting things together were loose. They were hold in place only by the housing and one of them was already eating the housing. I presume as the gears and syncro were loose that this was causing the jumping. The syncro from what I could see is fine.

I am a bit annoyed as I could have fixed the box without having to remove and replace the box at all.

I uploaded the following picture of the box with the 5th gear removed.

https://www.fiatforum.com/gallery/uploads/87440/gearbox_postmortem.jpg

The two bolts are now tightened they were loose almost falling off and only the cover was keeping them in place.