Gear change issue question - faulty synchro?

[Peter C]

Gents,

 

This relates to my dear old W124 200E, I’m after a little technical advice.

 

5 speed manual, in-line engine, RWD.

 

Changing down from fourth to third and third to second gear the gearbox works fine, the changes are smooth and don’t crunch.

 

But changing up from first to second needs a slow hand to avoid a crunch. Likewise selecting first at any speed will result in a crunch. When stationary all gears go in ok and the clutch doesn’t drag.

 

Knackered synchros?

[Mrcento]

When was the gearbox oil last changed? Does it get better/worse when the car is hot or cold?

 

Do you ever have difficulty selecting reverse?

 

Small Fiat gearboxes tend to go a little like that, it's usually related to either clutch adjustment, tired gear linkages or a stretched reverse inhibitor cable.

 

I tend to find on all old gearboxes, if the synchros are getting worn, you'll notice it in third before any other gear.

[Peter C]

No idea about the last oil change.

 

Fully warmed up the change is a little smoother but still crunchy.

 

Getting reverse is always tricky in a W124 but this ‘box is no different from others that I’ve experienced.

[red5]

Assuming clutch clearance is good, oil or synchro hub wear. Always worth an oil change.

[wuvvum]

If second gear synchro was worn I'd expect it to crunch more on downshifts than upshifts (unless you're blipping the throttle when you change down).

[The Reverend Bluejeans]

Worn out baulk ring. Secondhand gearbox req'd.

 

It would be worth getting the oil examined to see how much granite there is. 

[Mrcento]

  On 30/11/2018 at 07:41, Peter C said:

No idea about the last oil change.

 

Fully warmed up the change is a little smoother but still crunchy.

 

Getting reverse is always tricky in a W124 but this ‘box is no different from others that I’ve experienced.

 

Well seeing as there is "some" noticeable difference with temp, oil change should definitely be on the cards first. Would also provide decent analysis with what came out/what was floating in it.

 

Even if it is a tired synchro, there's a good chance fresh oil will give it a new lease of life. I wouldn't rule out clutch btw, you might not think it's dragging but when they do, 1st, 2nd in motion and reverse selection tend to be where it shows, often isn't noticeable stopped.

[Rocket88]

Merc manuals aren’t great.....about 80% are autos for a reason.......as above sages have advised, change oil, snake oil additive not a bad idea

 

 

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[stonedagain]

I had a similar fault on a E28 518i. There was a felt ring fitted in the crankshaft, presumably to keep crap out of the spigot bearing. This bush was dried out & hard, causing the gearbox input shaft to drag. I scraped a small amount of the felt away with a craft knife, applied a smear of grease inside the bush. Job sorted!

[sierraman]

Sometimes when it’s gone for yonks on the old oil putting fresh stuff in that’s a bit thinner can start new noises. I’d probably live with it and take your time when the box is slow or double clutch it.

[Parky]

According to the Comma site, your car needs their AQM transmission fluid - yes, ATF in a manual box.

 

It also suggests a 20000km replacement schedule so I definitely agree that a box full of new fluid with a shot of something like Molyslip wouldn’t do any harm. If nothing else a couple of bottles of transmission fluid will be a cheaper option than a rebuilt box. Heck Of a lot easier to install as well.

 

Draining the old oil will also reveal if it is full of metallic crap indicating some sort of internal issue. If that’s the case the oil change won’t help much but it still works and at least you have fresh oil in the box

[Crispian_J_Hotson]

Top of me head, changing up issues would be adjustment, cable, selector box worn etc. You can change up without using a clutch if you get the revs right, it'll slot in fine. 

 

Changing down issues will be a knackered box. (You'll need a clutch for that bit).

[Peter C]

Thanks guys.

 

If the ‘box was crunching when shifting down into second then I would have concluded that I have a synchro issue but the issue is on the up change.

 

I will look at the linkage and try to change the oil.

 

I know about the ATF thing in a manual ‘box, crazy.

[Andyrew]

Baulk ring sticking or worn I'd guess.

 

Change the oil first, wont cure it but may improve it.

 

R380 on a discovery is usually naff on the first to second change, I usually give it a little blip on the throttle to on the change or let the lever go into neutral first,

[DSdriver]

  On 30/11/2018 at 23:05, BoggyMires said:

...Changing down issues will be a knackered box. (You'll need a clutch for that bit).

Ahh, the lost art of the double declutch

[MikeR]

I think I used ATF on the 240 4 speed manual box ,

 

what came out was black at 120K , red stuff went back in ..

 

it worked a lot better , despite having play in  the output shaft bearing

[NorfolkNWeigh]

As a lazy fucker, I'd be inclined to do as others suggest and just adapt to it. Unless you're under 20 it'll probably outlast you, so why worry.

[Guest Hooli]

I wonder if ze Junkman knows how much oil these take?