KE Gearbox - crunching into 2nd

[chrisvine]

When I acquired my S2 it was essentially a non-runner, so I thought it sensible to have the gearbox reconditioned when it was apart rather than find out any hidden problems once it was rebuilt.

Now it's all back together, it's very difficult changing down into 2nd and it mainly results in crunching of the mechanism. It's ok double clutching so my assumption is it's probably an issue with the synchromesh. As with most rebuilds it's taken a lot longer than the typical year's warranty for a recon before it came to light.

I've only a basic knowledge of the workings of a synchro gearbox. I was hoping (fooling myself) that it might just need 'bedding in'. Although being unable to select a gear would point to a lack of friction between the synchro and the gear stopping them engaging.

Could anything else cause problems selecting a gear?

Chris

[Heuer]

Reproduction synchro rings are not good because they are not hardened as the original were. If you get 5,000 miles out of a reconditioned box you will be lucky. Rob Beers sells properly made synchro rings but they cost ?124 each compared to ?34 each for the useless ones.

[abowie]

Probably won't help but worth a try putting Redline MT90 into it.

[chrisvine]

Thanks David, Andrew.

By having it reconditioned, I may have inadvertently achieved what I was trying to avoid!!

Although it's only covered a hundred miles or so since it's been rebuilt. It had sat without oil for almost a year before being fitted, which wasn't ideal and I was wondering (hoping!) whether that had possibly caused issues that would ease once run in. I had filled it with the MT-90 oil after reading recommendations on an earlier thread.

I suspect I will have to consider taking it apart in the spring and have a stab at rebuilding it with Rob Beere components.

Chris

[christopher storey]

Chris : before you get totally despondent about it, take the console and cover off , and have a good look at the remote linkage and in particular the three selector rods, to see that they all rotate freely and move back and forward freely, and that the base of the gearlever engages each rod one at a time. It only takes a fractional misalignment for the lever to move more than one rod for part of the travel, and then all sorts of untoward effects can result. If they are stiff in any plane, then the first thing I would try is lubrication with eg silicon spray grease or similar.

Check also that inside the gearbox, the selector forks are securely attached to the selector rods. You will have to take the lid off for this, but it is not difficult . The reason I suggest this is that if by difficulty in changing down , you mean stiffness which suddenly gives way and results in a crunch, this is more suggestive of a selection problem than a synchromesh problem. Also, if it is a big synchro problem, then you would expect it to crunch on upward changes as well as down changes, albeit to a lesser extent.

Just another thought - put it in 2nd at a modest speed, say 2000 rpm, and alternately accelerate/decelerate . An internal fault, rather than a selection fault, will often show up as the lever moving backwards and forwards under load reversals

[David Oslo]

That is excellent & detailed advice from Christopher. Exactly what the Forum's all about :D

Chipping in my 5-pence worth I would have a look at the fibre washers and special springs on the pivots of the gearlever, check nothing is loose or overtight, give the pivot pins a good lubrication with suitable oil. Then check for engagement of the little ball end onto the half cups on the selector rods just as Christopher describes.

If / when taking the cover off, it's worthwhile to clamp the cover onto the workbench / vice and give it a good number of "gear changes". Feel and listen for graunching or looseness. Inspect the ends of the fingers that engage onto the selector ring, it may be the fingers are badly worn and compounding the situation. Maybe the selector rods have accumulated rust and crud where they rest in the cover itself and need a good cleanout with degreaser and re-lube. Detent balls and springs in the cover similar story.

Lot's of easy checks before things get grim.

[PeterCrespin]

As well as your double de-clutch check, I would double check de clutch.

[abowie]

Just another thought - put it in 2nd at a modest speed, say 2000 rpm, and alternately accelerate/decelerate . An internal fault, rather than a selection fault, will often show up as the lever moving backwards and forwards under load reversals

Chris can you expand on this for me please?

[Alty Ian]

O n t h i s

How's that Andy?

I'll get my coat

[christopher storey]

Andy : I only know about this because on my S2 with a KE box, which is not a terribly wonderful example at all, I think the thrust bearings are worn, and one of the shafts in the box quite plainly moves back and forth against the thrusts according to whether drive or overrun is occurring , taking the selector forks with it , and this shows itself as a forward and back movement of the lever through perhaps 10mm at the top end . There is no such movement on my S1 FHC with EJ box

[abowie]

O n t h i s

You sooo funnee

[chrisvine]

Thanks for all the helpful advice. I've taken the gearbox cover off to investigate and found that there was a missing Tufnol washer connecting the selector lever (72) to the pivot jaw (66) but also the spring washer had been fitted the wrong side where the pivot jaw connects to the gearbox cover. Correcting these should remove much of the current slack in the movement of the lever.



This would also explain why I was having trouble with gear lever just coming into contact with the gearbox cover and possibly why a PO had cut away the front section of the cover (which I 'fixed' by adding new metal!). With central console in place, the addition on the convoluted rubber gaiter would often cause it to pop out of 2nd and occasionally 4th.

Correcting the spring washer should gain about 8mm which might be sufficient to cure the clearance issue. The parts are on order including the thinner v12 gaiter which I've since read others have fitted instead of the bulbous one.

As Peter suggested, I'll first check the clutch is disengaging correctly. The plan is to press the clutch to the floor. Handbrake and footbrake off, on level ground, wait 10 seconds for the gears to stop spinning (if the clutch is working this should happen). Then ease it into second. If the car shows signs of wanting to set off or roll forward then the clutch isn?t disengaging properly and the synchro is acting as the clutch to set the car off.

Another suggestion was to do a series of tests of stationary car to see what the behaviour is like when depressing the clutch and pushing the gear lever immediately and firmly into the chosen gear without any wait.

Repeat this for each gear, but with a full ?re-set? each time, i.e. restart the whole procedure from neutral and clutch up each time. If the 2nd gear synchro is iffy, but clutch (clearing) OK, then all gears will go in without graunching whether on a fast or a delayed lever push except for 2nd, which will graunch in the ?no-delay? instances at least.

After that I'll take the lid off to investigate.

Thanks again,
Chris

[PeterCrespin]

Not sure on the rather complex clutch protocol but will be interested to hear. A big clue is whether the bite point is near the bottom of travel and/or a slow-idling engine with the clutch depressed stalls or slows further when you select first or reverse.

My test would be akin to bump starting a race bike, which is bloody difficult in full leathers if the clutch is dragging. I'd just get a glamorous assistant - or your wife - to press the clutch down while you try to push the dead-engine car in first or reverse. If it is significantly different to neutral the clutch is dragging.

[chrisvine]

An update: the checks confirmed that the clutch was disengaging correctly and there was no graunching in any gear doing the stationary test; depressing clutch in neutral and firmly selecting a gear.

With the gearbox cover removed to correct the missing Tufnol washers and repositioned the spring washer, I took it for a spin to see if there was anything obviously wrong. I'd only done a static test before fitting the cover.

I think the sprung plunger to resist reverse being engaged doesn't provide sufficient resistance. Correcting the mounting of the gear lever has taken a lot of free play out of the gear selection movement. The combination of the plunger and the geometry being slight out due Tufnol/spring washers meant it was a fine line between selecting 2nd or reverse and not the synchro after all! Phew!

Now the only slight niggle is occasionally not being able to engage 3rd from 2nd. The 1st/2nd selection rod doesn't always quite reach the neutral position but allows the lever to cross the gate for 3rd. The interlock is doing its job and stops engagement.

it might be how I'm trying to change gears, pushing sideways and forwards rather than three distinct movements? Although I'm tempted to take the top of the gearbox off to see if there's too much resistance in the movement of the 1st/2nd selection rod for the detent to pull/hold it in neutral. Does that sound plausible?

Chris

[christopher storey]

Ah yes, I sometimes get the baulking going from 2 to 3 on my S2 box. You are luckier than me, because on mine the only cure is to go back into 2nd and then try again - I just get left with a box of neutrals which is not what you want when overtaking ! If I may offer a suggestion, light finger pressure and " palming" the lever to guide it, rather than grabbing hold of the lever ,may help