Now I'm paranoid, sorry! 2nd gear seems tough

[Ads1987]

Hi Guys,

Sorry for another gearbox post, my 1.7D's 4 speed box finally gave up the other day, it got stuck in 4th and was knackered. I can't afford a proper rebuild at the mo as I'm still paying for the engine rebuild, so I found a second hand one on eBay that had done 70,000 miles.

With some help of a friend this has now been fitted, emptied of gearbox oil and refilled with 80w90 gl 4 spec from Brickwerks with new seals etc. The aim is to drain and refill with 75w90 and molyslip in a few weeks once we've done a few hundred miles.

Now the problem is 2nd gear seems to crunch when slowing down, if i pull from 1st to second whilst speeding up it's fine but if for example i'm pulling up to a junction and slowing down it seems to grind, a bit like if you didn't fully depress the clutch. Now I understand you want to use your brakes more than your gearbox as pads are cheaper etc, but this is once I've slowed down and I'm changing to second ready to pull away. I've tried pumping the clutch which doesn't help, also double de-clutching which i'm not great at and this seems to help but only sometimes.

The old box never had this issue, I've tried adjusting the linkage spline, bracket at the box and bottom of gear lever, just in case anything got knocked in the swapover but no difference. At some point 1st and second couldn't be selected when stationary but now all gears select when stationary, it's purely just second gear when slowing down.

If i were new to the van i'd say I just couldn't drive properly but I'd like to think after 4.5 years of owning it and judging by the last gearbox not suffering this fault that something may be different with my new second hand box?

Sorry for the essay, Any ideas?

Cheers (again!!!!)

Adam.

[jrt]

Not that i know too much but when you say (gear selection) when stationary is that with the engine running or turned off. Have you checked the fluid/bled the clutch ?
David.

[Ads1987]

that's engine off, not bled it as only fitted the gearbox Saturday, wasn't long ago the brakes were bled but to be fair clutch fluid was a while ago. I didn't think it would be this as was only affecting 2nd gear, but i'll try it anyway!

[stigma]

sounds like the synchro ring is worn, when up-shifting your engine rpm will drop synchronising the shafts, on down-shifting you have engine going down and then syncho trying to spin up the shafts, try maching the revs to current gear, you will not need good sychros (or even working clutch) at all.

[Aidan]

it could be that the gearbox mount is worn so allowing the box to move relative to the linkage or it could be that there is wear in the pinion bearing in the box - I'd look at the external first, mount and linkage and when driving try to do a dummy go for first before changing to second, you don't need to engage first just start to push the gearstick forward a little with the clutch down before you go to 2nd
re the 70,000 mile gearbox is that backed up with full mot record or just what it said on the speedo or what you were told by the vendor ?

[937carrera]

^^^ Synchro hub or worn dog teeth (or more likely what Aidan just posted)

Here's a handy link for double declutching, though you'll only need to do single https://en.wikipedia.org/wiki/Double_clutch_(technique)

[Aidan]

On the 4 speed box 1st and 2nd change gears are on the pinion shaft, the fixed gears are on the mainshaft so if the clutch is depressed the mainshaft is not being rotated by the engine so the change gears are undriven and the synchroniser should easily be able operate the synchrorings and the slider engage the gears to lock them to the hub and engage them
3rd and 4th fixed gears are on the pinion shaft so they will be driven by the differential when the vehicle is moving thus the 3rd and 4th change gears are also driven even when the clutch is depressed (the shaft is slowing down/stationary) so the synchroniser has more work to do selecting those gears; 3rd gear has the best synchro ring partly because of this partly because it is the most operated gear, sometimes 2nd gear has the same ring fitted, but it is the 2nd best ring otherwise, 1st gear synchroring has the fewest dog teeth as it is mostly engaged when stationary.
2nd gears get battered by people rushing the first change of the day when cold when the oil is filling the low gear rings and is gloopy and reluctant to be pushed aside by the ring which is trying to displace the oil, grab the gear, slow it down and align it in time for the slider to engage it

[sarran1955]

Hello,

On the 4 speed box 1st and 2nd change gears are on the pinion shaft, the fixed gears are on the mainshaft so if the clutch is depressed the mainshaft is not being rotated by the engine so the change gears are undriven and the synchroniser should easily be able operate the synchrorings and the slider engage the gears to lock them to the hub and engage them
3rd and 4th fixed gears are on the pinion shaft so they will be driven by the differential when the vehicle is moving thus the 3rd and 4th change gears are also driven even when the clutch is depressed (the shaft is slowing down/stationary) so the synchroniser has more work to do selecting those gears; 3rd gear has the best synchro ring partly because of this partly because it is the most operated gear, sometimes 2nd gear has the same ring fitted, but it is the 2nd best ring otherwise, 1st gear synchroring has the fewest dog teeth as it is mostly engaged when stationary.
2nd gears get battered by people rushing the first change of the day when cold when the oil is filling the low gear rings and is gloopy and reluctant to be pushed aside by the ring which is trying to displace the oil, grab the gear, slow it down and align it in time for the slider to engage it

Those sir, are the best 3 paragraphs I've see on a 4 speed volksy box since John Muir..

Cordialement,

[Ads1987]

thanks guys, a little confused reading all that but it will sink in!

no guarantee on the box as just an eBay buy for £225, no history just sellers word, i'll try bleeding clutch at the weekend but it sounds like its unlikely to fix it! have tried all external adjustments and already has a pretty new polyflex bush so I think I may just need to live with it for now.

Good tip about the dummy 1st gear, I used to do that on the old box before I replaced all the worn linkages and that helped.

I haven't gone for a proper drive yet but it seemed to improve as it warmed up so I guess that would point more to wear in the box then - oh bum!

so re the double de clutch link, I only need to single and match revs ?

[937carrera]

so re the double de clutch link, I only need to single and match revs ?

Yep

- I used to practice technique by simply easing pressure off the gearbox, slipping into neutral, then accelerating engine or waiting until revs dropped to an appropriate speed before selecting the new gear. No clutch used at all. Always a few crunches when I was out of practice

Aidans comment regarding cold boxes is absolutely true. I have a truck that is reluctant to go into second gear until it's been driven 300 yards. Lived with it for 12 years so far.

[Ads1987]

I did used to blip the throttle in neutral whilst clutch down and changing gears but stopped this as read that it doesn't really help to match the gear speed?

I understand 2nd gear in most older manuals is tricky from cold just couldn't seem to work out the best solution, looks like slow down earlier let off the brake to decrease the load and then speed is a better match so it should be easier to go into 2nd?