lost 4th gear?!?

[smokeejoe]

Please help was just driving home, at a reasonable pace. Shifted into forth and it jumped straight back out again i tried repeatedly with the same result all other gears are fine, gearbox oil was changed when i did the clutch around a month ago.

What have i done?

Is there anything i should check? or do i just have to bite the bullet and get replacement gearbox? or can i rebuild it?
Any advice would be great.

Cheers joe

[pk_090]

does it engage but not drive? does it mesh or gind?

[kaiowas]

Doesn't sound promising. Probably worth having someone try going through the gears with the car stationary whilst you watch the selectors to make sure they're doing what they should, this will eliminate any linkage issues but tbh if you've only lost a single gear it's almost certainly something internal.

Does it go into gear smoothly then pop up out under power or is there resistance when engaging it? Does it drive ok if you hold the lever in 4th?

[smokeejoe]

It will engage but pops out as soon as i feather the throttle.
I did try to hold it but makes lots of horrible crunching noises.

Do i need a new box or isit it possible/worth the effort of repairing?

[elbon50]

It will engage but pops out as soon as i feather the throttle.
I did try to hold it but makes lots of horrible crunching noises.

Do i need a new box or isit it possible/worth the effort of repairing?

Needle roller bearing breaking up I suspect Joe

Peter

[smokeejoe]

Is there anything i can do too make sure before i rip the box out?
If it is the needle roller bearing are they exensive? and are they diffucult to replace?
cheers

[PW@Woodsport]

Check your cables/linkages/brackets/bushes/square bush etc before condemning the gearbox, most Mr2 gear selection issues are external and something very simple to rectify.

[elbon50]

Check your cables/linkages/brackets/bushes/square bush etc before condemning the gearbox, most Mr2 gear selection issues are external and something very simple to rectify.

Totally agree

Always go for the simple possibilites first

Was just suggesting a possible cause (assuming it selects OK & then pops out)

Perhaps it isn't engaging properly

Peter

[smokeejoe]

Thanks for the advice will have a good hunt around and see if I can spot anything wrong
fingers crossed it's something simple
cheers joe

[tonigmr2]

TBH that does sound like a selection issue to me, you're not properly engaging it which is why it pops back out on touching the throttle. Strong suspicion of cable tightness and linkage issues IMHO!

[elbon50]

Thanks for the advice will have a good hunt around and see if I can spot anything wrong
fingers crossed it's something simple
cheers joe

Is there any slackness at the gearlever end Joe ?

Discovered the reason for some sloppyness in mine in that area last week (although all gears did select with no problems)

Otherwise get an assistant to operate the lever while you watch what happens in the engine compartment

Peter

[smokeejoe]

Everything feels fine at the gear stick end and after remove the centre console all cables are well attached with no play.
Just had the car up on a lift and after watching the movement of the cables to select 4th i disconnected the cable, and with the engine runing and an assistant operating the clutch i manually selected 4th with the lever on the gearbox and as the clutch was slowly released it jump out of gear and if i tried to hold it, it made a horrible grinding noise. So the way i figure it this rules out any possible chance of any slack in cables?
Please correct me if im wrong!!
Is there any other checks i can do?
Where else can i look?
Thanks Joe

[scomr2]

Seems like you've pretty much eliminated a cable fault and doesn't sound like a wear issue as the pop-out would start to happen only under high load occassionally before developing into what you are describing as the wear gets excessive. Another thing you can check is to drain the oil - if it's shiny and full of metallic flakes then something catastrophic has happened internally and only dropping the box will determine exactly what.

[elbon50]

So you've just replicated the symptoms you experienced when the problem first started Joe

Seems to me to be definately damage inside the g'box

Selectors, synchro hub, bearing. Difficult to be sure

Don't know if we have a member who specialises in g'box problems on here. Paul Woods will know a lot about this sort of thing on the AW11

PM him perhaps. Tell him what you just found out

Good secondhand box should be easy to get from another member or a breaker

Then you could strip & examine this one at leisure later if you fancied it

I have my original box in bits at the mo. Put a used one in & that solved the problem for time being

Good job this didn't happen when you were in Germany

Peter

[PW@Woodsport]

Your test of manually trying to select 4th has pretty much confirmed it is an internal issue, but without a stripdown it would be almost impossible to say exactly what has failed.

I rebuild the C series almost every week so i'm very familiar with its inner workings. The synchro hub is not being allowed to engage with the selector ring or if it is engaging there is nothing holding it there.

Now the only thing i couldn't decipher from your test was wether it stayed in 4th if you held it there (and slowly released clutch) or if you only got the grinding noise when trying to re-engage after it popped out with a partially engaged clutch, i presume you couldn't hold it in 4th at all?

If that isn't the case and it could be held in 4th then you might want to check the selector detent for 3rd/4th, it's on the end of the gearbox just before the 5th gear end casing, you will see two allen key plugs right next to one another, now i can't remember offhand which one is for 3rd/4th and which is for 5th/reverse (the 1st/2nd detent is near the bellhousing) , but it takes 2 minutes to undo the plugs, and remove the detent housing/spring, a little ball bearing should roll out too. if either of the detent housing is seized, or springs broken, or for some reason the ball bearing is damaged (highly doubt it) then that could well be your problem.

Ignore all of the above if the gearbox won't stay in 4th even if you hold in there all the time. My best guess would be the 4th gear synchro hub has collapsed but could be literally anything on 4th. As ScoMr2 said, drop your oil and if it has metallic bronzy bits in it then its time to replace the box.

Hope that helps.

[smokeejoe]

Thanks too everyone for taking the time to donate their wisdom.
Yes peter im glad this didnt happen in germany dont know what i would have done.
Paul it will not stay in forth at all as soon as the clutch is gently released it starts to grind if i try to hold it in place, i will however do the checks you mention just to be sure before i fork out for another box.
But assuming that doesnt work does anyone have a good mk1b gear box laying around? the closer to norfolk the better as i expect postage will be ridiculous.
Cheers joe