Trouble selecting 5th gear

[viperbluecerb]

Evening all. Here is an interesting one. The last couple of times I have been out, shifting from any gear into 5th gear has become a problem. No nasty noise, no grinding, just won't go in. So I went out for a drive this evening and discovered that if I attempt to go into 5th to the point where the gear lever won't move any farther forward (but is not anyway near close to being in gear), if I then move the lever back ever so slightly and try again, it goes into 5th every time on this "second" attempt. Very weird. No nasty crunching or funny noises, no issues with other gears so I am pretty confident it is not a synchro or clutch issue. Is there anything special about 5th with respect to the selector or other internals? Thoughts highly appreciated!

[Tanguero]

If you are sure that the clutch is disengaging properly it sounds typical of the 5th gear synchroniser either not sliding freely on the shaft or one of the inserts getting damaged and jamming things up. The trouble shooting section of the gearbox rebuild manual suggests it is the former. Unfortunately there isn't likely to be a cure apart from dropping the box and taking it apart.

However a borderline clutch can make it more difficult to select on particular gear before it fails to the point that you cant select any. Have you tried topping up and bleeding the clutch? If that cures it even temporarily then its probably a clutch problem rather than gearbox.

[N7GTX]

If you can select reverse easily enough that would tend to rule out the clutch and help narrow it down. I would agree with Tanguero that the synchro is probably the cause.

[viperbluecerb]

Thanks a lot guys, much appreciated. I have a long drive coming up this weekend so will see how I get on and if the problem gets worse or starts to affect other gears.

[viperbluecerb]

Tanguero said:

Have you tried topping up and bleeding the clutch?

I did this around 4 months ago and the reservoir was full. No fluid leaks since then, so I think this is OK, will check again though.

[viperbluecerb]

Found an interesting explanation of synchro rings here:

https://www.youtube.com/watch?v=MXsRfbOiBhE

This guy refers to a "block out" condition that can occur when the synchro ring cannot index due to a worn slot or mashed teeth. You learn something new every day

[Tanguero]

viperbluecerb said:

Tanguero said:

Have you tried topping up and bleeding the clutch?

I did this around 4 months ago and the reservoir was full. No fluid leaks since then, so I think this is OK, will check again though.

I was meaning, top up and bleed the clutch then immediately try 5th. That would tend to eliminate the possibility that its a slow clutch leak. A slow leak or regurgitating seal wont always be terribly obvious, but if it wont go into 5th with a freshly bled clutch then its almost certainly the synchro on 5th.

Rebuilding the T5 is a pleasantly easy task if you are methodical. A rebuild kit from the USA will cost around half what a UK sourced one does even allowing for international shipping. I used these people - http://www.thegearbox.org/T5.html and am more than happy to recommend them.

[viperbluecerb]

Tanguero said:

I was meaning, top up and bleed the clutch then immediately try 5th. That would tend to eliminate the possibility that its a slow clutch leak. A slow leak or regurgitating seal wont always be terribly obvious, but if it wont go into 5th with a freshly bled clutch then its almost certainly the synchro on 5th.

Ah OK, understand now, thanks. Also thanks for the T5 rebuild kit link, very helpful.

[ukkid35]

You might want to consider fitting this 'Counter Gear Stabilizer' as well

http://www.5speeds.com/t5.htm

[Tanguero]

viperbluecerb said:

Tanguero said:

I was meaning, top up and bleed the clutch then immediately try 5th. That would tend to eliminate the possibility that its a slow clutch leak. A slow leak or regurgitating seal wont always be terribly obvious, but if it wont go into 5th with a freshly bled clutch then its almost certainly the synchro on 5th.

Ah OK, understand now, thanks. Also thanks for the T5 rebuild kit link, very helpful.

They do some nice enhanced parts too, like the billet cluster support plate to replace the standard pressed steel one and billet synchro keys. The only thing that I would avoid are the phosphor bronze bush replacements for the selector forks, I changed back to the standard plastic ones as the bronze ones clattered and rattled after very little wear. All the other goodies have been great.

[ukkid35]

Tanguero said:

They do some nice enhanced parts too, like the billet cluster support plate to replace the standard pressed steel one

= Counter Gear Stabilizer

Interesting, but the one in my link above includes shims whereas thegearbox.org one does not - how critical is that?

[Tanguero]

ukkid35 said:

Tanguero said:

They do some nice enhanced parts too, like the billet cluster support plate to replace the standard pressed steel one

= Counter Gear Stabilizer

Interesting, but the one in my link above includes shims whereas thegearbox.org one does not - how critical is that?

That looks very similar indeed to the one that came with my kit. The kit I had included a set of peelable shims to go with the plate although it doesn't seem to be listed on the website.

ETA - Yo are going to need the shims to set the correct end float/preload regardless if if you use the standard pressed sheet retainer plate or the billet one.

Edited by Tanguero on Saturday 30th August 17:08