Serie 2a gearbox. Doing without the 3/4 synchro?

[Pepé le Pew]

Hello all,

I have the gearbox in parts on the workbench and i had a bit of a think today.

I like unsynchronised boxes and have been driving them a lot in my live.

Seeing that the 3 leafsprings in the synchro clutch are prone to breaking and in the worst case jamming up the box.

Wouldn't it be possible to discard the synchro rings and just use the centre hub with the gears.

Or would it be near impossible to get into gear because of the straight teeth on hub and in primairy pinion and third gear?

Cheers,

Eric.

[secondjeremy]

The springs hold the thing in the engaged positions or the neutral position. If you cut the rings off and sought to rely on the centre selector ring and the springs it might work but there may be trouble with the ring movement not being restrained by the synchro rings and moving too far.

When new the synchro rings have sharp grooves and wider grooves to cut through the oil film on the cone and assist the rings to provide enough friction to do their job. Maybe if you destroyed the grooves etc (ie machined flat) you'd achieve the desired result.

This type of synchro has no baulk rings and so doesn't impede the gearchange action in the way that the 1st-2nd synchroniser does on a S3 box. Push too quickly on a 1st/2nd synchroniser and it resists - this one merely crunches. In fact it works rather well considering it was designed in the late 1930's but the length of the lever etc are part of the design - slowing the movement to something that it can cope with.

[bill van snorkle]

There are hundreds of series vehicles happily running around the world with broken leaf synchro springs lying in the bottom of the box, so there should be no issue fitting the box up without them.

[Pepé le Pew]

The springs hold the thing in the engaged positions or the neutral position. If you cut the rings off and sought to rely on the centre selector ring and the springs it might work but there may be trouble with the ring movement not being restrained by the synchro rings and moving too far.

In my opnion the centre hub is held in neutral and engaged position by the detent springs and balls on the slector shaft and not by the leafsprings in the schynchro clutch. The leafsprings only hold the synchro rings in the centre position when not engaged and prefent it from rattling.

Correct me if i'm wrong.

My idee was to drill out the 3 rivets that hold 1 ring to the pillars and slide of centre hub. Discard the rings, pillars and leafsprings and only use the centre hub.

The reason i took the gearbox apart is that i had a ticking noise in 3 and 4 under power. Mainly between 50 and 70 Km/h. More prominent in 4th and getting less as the box got warmer.

I suspected the synchro clutch and what i have found is that the 3 leafsprings are still in there place but there are severe scoring marks on the sides of the 3 hourglass shaped pillars. The ring on the centre hub is rattling against the pillars under power.

I'm trying to figure out why it does that. The rest of the box is in very good shape. Its an overhauled box from Whitehouse and son that has done 20000Km in 1 1/2 years. All the bearings and gears seem fine.

The only other thing a found is that with only the mainshaft and its big bearing in the box i can wiggle it a bit.

There is no play on the bearing itself but the outer race of the bearing moves a little bit in the carrier. There is no evidence of it turning in the carrier though. When i fit the bellhousing with the front mainshaft needle bearing in de primairy pinion the mainshaft is solid with no play.

As Bill states. There are a lot of serie Landrovers running arround with the 1 or more leafsprings missing from the synchro but in my opnion that must make a lot of noise and a lot of wear on the pillars as it rattles about.

Cheers,

Eric.

[bill van snorkle]

Eric, The synchro springs purpose is to pressurise the synchro cones so that the desired gear and mainshaft speeds are equalised before the dog teeth engage. Removing the 3 pins and bronze cones will simply as you state, convert the box to non synchro,minus some of the attendant rattles.

[Pepé le Pew]

Your right Bill. As i see it the springs only pressurise the rings when you start the shifting motion and as long as they are in the recesses in the pillars they push the ring against the cone. After the ring hits the cone the springs come out of the recesses and the dogteeth engage. The rings are then no longer pressed against the cone and are able to move arround a bit.

I was at my parts supplier yesterday and he showed me some other ones for comparison.

One was from Bearmach. One a very worn genuine one from a 2a gearbox he took apart not to long ago and one new old stock for a serie 3 suffix D box.

Mine is 100% identical to the new one from Bearmach. The rivets that hold the rings to the pillars differ from the rivets on the genuine parts.

The main thing i noticed was that the leafsprings on the two genuine ones were a lot firmer. Even on the very worn 2a synchro. I had to apply more force to twiste the inner hub against the pillars. The springs on mine and the Bearmach version feel sloppy.

I also made some pictures of the scoring on mine. The very worn 2a one had no scoring on the pillars at all by the way.

I also noticed that the serrated theeth on 1 side of the rings are higher than on the other side while the serrations are not worn away.

Both rings have this. Looks to me like the rings were not centred properly when they were machined.

LRseries told me they still have the genuine article in stock. Not cheap though. I decided to order one. I'm having far to many problems with pattern parts the last couple of years.

Cheers

Eric.

[secondjeremy]

I've seen eccentric wear on the cones and attributed it to a broken or misplaced synchro spring.

The springs go soft with age and fall out. I used some aftermarket ones that seemed very strong and had slightly longer tails than the genuine ones. The change was truly apalling. Bearmach ones looked very similar to the genuine article and gave a nice change action.

[Phil Hancock]

There is no need to drill to strip, sit the bronze ring on top of vice jaws that just clear the linking bars and punch the bars out.

[Pepé le Pew]

I've seen eccentric wear on the cones and attributed it to a broken or misplaced synchro spring.

I don't think this is eccentric wear Jeremy. The serrations are still intact on the thinner teeth. If it was wear the serration would be gon one that side.

What do you mean by "The change was truly apalling"? The stronger spring made shifting worse?

I have no problems with the shifting of is box. Very smooth. But i just was annoyed with that that ticking sound in 3rd and 4th.

Cheers,

Eric.

[Pepé le Pew]

There is no need to drill to strip, sit the bronze ring on top of vice jaws that just clear the linking bars and punch the bars out.

You've done this before Phil?

Ever tried to run the gearbox without the 3/4 synchrorings?

I guess drilling of the riveted heads first might make it a bit easier to punch them out.

Cheers,

Eric.

[secondjeremy]

Changing gear was very hard work - the lever needed to be forced to get the thing to engage.

Synchro cones as it were look very worn to me. There should be a number of fine radial cuts in the bronze as well as the slots. There is also the question of the marks in the cone support pillar which suggets something has been running eccentrically and touching - and causing noise?

[Pepé le Pew]

Changing gear was very hard work - the lever needed to be forced to get the thing to engage.

Synchro cones as it were look very worn to me. There should be a number of fine radial cuts in the bronze as well as the slots. There is also the question of the marks in the cone support pillar which suggets something has been running eccentrically and touching - and causing noise?

The cones are not worn. The serrations on the teeth are in good shape. They just don't show up in the pictures. I made dose with my i-phone. I don't have a good digital camera.

The marks on the pillars are definitely made by the centre hub and i blame that on the weak springs.

When 3rd or 4th is engaged the brass cones flop around a bit and the pillars rattle against the disc on the centre hub.

When the synchro is in neutral de centre hub is in line with the recesses in the pillars so then there is more room for it to flop around before it hits the pillars.

Cheers,

Eric.

[Phil Hancock]

You've done this before Phil?

Ever tried to run the gearbox without the 3/4 synchrorings?

I guess drilling of the riveted heads first might make it a bit easier to punch them out.

Cheers,

Eric.

I have demolished quite a few to separate the steel scrap from the bronze scrap, IIRC they are a press fit not riveted as they just punched out. I had wondered about running a full syncro smash box myself many years ago but never got round to it and ended up running a series 3 box instead.

[Snagger]

Your plan should work fine, but replacing the faulty parts would be better. I'm more concerned with the reason for their damage, though. To cause that damage, the centre hub must be sliding skewed in relation to the cage. The only things I can think of that could allow or cause that to happen are an excessive gap between the synchro cones on the third gear and input pinion, allowing the cage itself to misalign inside the box, a bearing or shaft wear issue allowing the hub to run out of alignment, or a selector fork/rod fault forcing the hub out of true (which should be contained by the shaft splines inside the hub anyway). I think you might want to compare the length of the old cage to that of the new one, by sitting it on the third gear and putting the pinion on top and measuring the difference in total stack height; I'd wager that the failed cage is a pattern part that was made too short, preventing the synchros from keeping it aligned.

Use a bearing seating compound, similar to thread lock, to set the rear bearing in its carrier - it shouldn't be moving about as you describe. Then use more of that compound to seat the carrier in the casing - it's in the LR manual, but even LR didn't bother, and it's the source of the oil migration from gear box to transfer box: use the compound and you gear box refils will only have to be done every 12,000 miles for replacement, not replenishment.

[secondjeremy]

I sought out the replacement for the sealing compound specified in the S3 wrorkshop manual and used it carefully, fitted a new seal and assembled the whole thing very carefully trying to see if I could produce a box which didn't leak - and the oil still migrates to the transfer box (and the ground)

Bath sealant next time I suppose.

[Pepé le Pew]

Thanks for the feedback Nick.

The splines inside the centre hub and on the mainshaft are in perfect condition and with no play at all so the hub is not moving/tilting in relation to the mainshaft..

The synchrorings are definitely running skewed in relation to the inner hub when they are pressed against the cones on 3rd or the primairy pinion because the inside of the synchrorings is a little bit eccentric.

It crossed my mind that it might be that the mainshaft is starting to wobble a little bit under power because of the big bearing tilting a bit in its carrier.

This could explain why the ticking noise was worse in 4th then in 3rd. In 4th the synchro unit is at the end of the mainshaft and its weight will have more effect on the mainshaft then when it is in 3rd.

But i think this would put a lot of strain on the needle roller bearing inside the primairy pinion, but the inside of the pinion as well as the bearing itself and the end of the mainshaft look perfect with no evidence of wear or uneven load. The main bearing of the primairy pinion has no play at all so that is not moving in relation to the mainshaft.

I will certainly glue the bearing in its carrier and the carrier in the housing just to make sure. Would Loctite 603 do the job or is that to strong considering any dismanteling in the future?

I might as well put in a new bearing when i'm at it. After some searching i found that the SKF number for that bearing should be 6307-C3. Can anyone confirm that because that one has metric dimensions and i wonder if Landrover used metric bearings in the days of the serie 2a.

Now the wait is for the new,and hopefully genuine,synchro to compare it to the old one.

I'll clean everything in the mean time and put a new rear cranckshaft seal in the engine.

Cheers,

Eric

[Snagger]

I would use the proper bearing seating compound rather than a thread lock. I think I used a Locktite product. It cured my oil migration, and hadn't been used by LR (it was a factory recon unit). Sorry to hear it didn't seal your unit, Jeremy - maybe your oil weep is getting through between the oil seal collar and the main shaft, or between the seal and the casing? The ends of the collar and 1st gear bush would need to be very smooth and even to be oil-tight, and if either has any notches, nicks or taper, then oil could get through into the shaft splines and migrate back to the transfer box.

Eric, it sounds like all your synchro problems are due to the cage and rings. Distorted baulk rings would cause the problems you have, and could have been due to poor assembly or just from being dropped or hit with a mallet - they're surprisingly easy to distort.

[Pepé le Pew]

I would use the proper bearing seating compound rather than a thread lock.

All the Loctite products in the 6xx series are bearing seating compounds Nick. The threadlocks are the 2xx series.

I had a look at a couple of tech sheets and Loctite 648 might be the better choice. Higher and longer temperature resistance and better oil resistance.

Cheers,

Eric.

[Snagger]

I didn't know about that numerical designator - good to know! I think you're wise to go for the high temperature and duration product with high oil resistance - it's astonishing how hot transmissions, especially the transfer box, get.

[Daan]

There are hundreds of series vehicles happily running around the world with broken leaf synchro springs lying in the bottom of the box, so there should be no issue fitting the box up without them.

I would fit all new parts plus a magnet in the drain plug for this, assuming that the springs are magnetic.

Daan

[Snagger]

Spring steel and stainless steel are not very magnetic, at least not compared to mild steel. I don't think a magnet would hold the spring parts with the oil churning as fast as it does. That may be why the drain plug is hollow, forming an undisturbed spot free of oil flow, rather than a magnet filling the void and displacing all fragments into the oil flow.

[Pepé le Pew]

Hi all,

I went along with my original plan and took the synchrorings of the old unit and only used the centre hub.

The genuine part i received did look genuine and came in the right box but i found cracks in the 3rd gear ring on all 3 mounting points to the pillars so that one went straight back to LRseries.

I put the gearbox back in the car yesterday and had had a testrun without the props fitted. Went throuh all the gears and when i rev it up the whole box starts shaking. When i put the T-box in neutral there is no shaking at all.

next i fitted the rear prop and put in the seatbase lose so i had something to sit on and had a little testdrive.

The shifting is perfect without the synchro rings. With double clutching it slides in 3rd and 4th very smooth,both on up and downshift.

The shaking of the box is less evident while driving but when i hit exactly 80Km/h there is a lot of noise coming from T-box.

Just below the 80 and just above and there is no problem.

I concentrated on the main box because i thought the problem was in there and left the T-box as it was.

I might have been wrong all along and vibrations from the T-box were the cause.

I'll take the T-box off again and open that up.

Cheers,

Eric

[Snagger]

The sliding low range gear on the transfer box output shaft is very loose on its splines and tends to wobble unless under load, so that could be a cause of the vibration. Other causes could be lumps of debris on the hand brake drum or binding of the hand brake shoes on the drum. You will certainly get much more noise from the transfer box when testing - with the transfer box in neutral, my main box is relatively quiet in all gears, but with the transfer box engages (props off), the chattering at idle is unpleasant in third and horrifying in fourth. I thinks it's a characteristic of the design, and not necessarily a fault - my transfer box has been rebuilt and runs flawlessly, despite the racket.

[Pepé le Pew]

I know the low range gear is supposed to be very loose on the shaft,but it is only loose when low range is engaged. When in high range the low range gear sits snug on the dogteeth on the high range gear so it won't rattle when in high range.

Brake drum is clean and the shoes are not binding.Can't feel anything wrong with the bearings as it is.

Its not a lot off work to get T-box out and leave the main box in place. I better check all the bearings and the preload and especially i want to check the spigot bush that sits in the front output shaft.

Its just a shame i didn't pull it apart when i had it out the first time.

Cheers,

Eric.