Fith gear synchro hub spline failure.

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Kevin B
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Fith gear synchro hub spline failure.

Post by Kevin B »

Has anyone had any experience of the following problem.

Recently whilst driving my BX17 TD estate, I noticed some peculiar noises coming from the gearbox area when 5th gear was selected (like you do I didnt take too much notice of it at the time).

Then yesterday on the way home from work when selecting 5th gear a complete loss of drive occurred.

Further inspection revealed the splines are stripped off the syncro hub, and the mainshaft splines for 5th gear are damaged bad enough to scrap this item as well. The gearbox had never had any issues prior to this occurance.

Obvoiusly this is a gearbox out job as the mainshaft is damaged badly (could the damaged mainshaft assembly be changed out in situ without complete a gearbox removal ?). I am planning a trip to the scrapyard ASAP for a look on the scrap engine and g/box pile as these parts will be common to all late BE3 boxes.

Is this a common problem, as I have never seen a failure like this before.

Should I be stocking up on good s/h mainshafts and fifth gear syncro hubs in light of this failure, while they are still in relativeley plentiful supply (same basic gearbox is found on a multitude of Peugeot and Citroen applications) . As the new price on these parts are truly eye watering.

Thanks in anticipation.
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DavidRutherford
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Post by DavidRutherford »

Wierd. Never heard of that before. I would guess that something wasn't torqued up properly in the factory, and the 5th gear has been fretting on its splines for many years.

BE gearboxes are usually exceptionally reliable. The only issues I've ever heard of are teeth breaking off the diff (rare), or oil leaks (fairly common). So reliable in fact that I've driven many miles on a BE gearbox with no oil in it. I'd not long bought the car and hadn't checked everything yet. There was about an egg-cup full of oil in it. Filled it up and it was fine.

I'd just get hold of another TD-spec BE3/5 gearbox and shove it in, keeping your old one for spares maybe.
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kermit the frog
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Post by kermit the frog »

These gearboxes were also fitted by rover in their diesel engined 200 and 400 series
They even used the XUD engine.
The petrol versions also used this gearbox mated to the K series engine.
So there are lots out there. (don't know about the ratio's in the rover versions)

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CaM
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Post by CaM »

YES

2nd drive ever in my 205gti, it did this. caused by the mainshaft nut being too loose, and 5th fretting on the mainshaft... quite odd as I was doing about 70mph and lost all drive in top :cry: BE3 boxes at the time were very expensive over here. not so anymroe though.
my replacement had the same problem, it seems. althoguh I've covered 30k miles in it since then, and a fair bit of that is 'spirited' driving and it's held up well. pop the cover off any new box and check it's tight!

I priced the required parts ex pug new zealand and they wanted $3000NZ for them (around 1500GBP i guess) so I spent $550 on a complete box. now can buy boxes for about $100 :roll:
I wouldn't bother to repair it as the cost/effort far outweighs the benefit of a good secondhand unit.
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Post by jeremy »

Interesting - I'm sure if you search this (and other Citroen) forums you will be surprised at how little there is on gearboxes - which must say something about their reliability.

Whilst the BE3 may be splendidly reliable its also splendidly variable. To say that no 2 are the same would be an exaggeration but they are very model specific and in many cases (not TD as far as I remember) the estate one is different to the saloon.

So far as I know that's the limit apart from the different gear change pattern on the pre 89 ones (Reverse - lift a sleeve - by 1st) and the final drive changes already mentioned they are all of similar strength. (Not a re-inforced version for 16 valves or TD)

A N/A diesel has a top gear of about 23 MPH per 100 RPM - TD about 26.5 - so a NA box might give sprint ratios!
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Post by CaM »

what kind of rpm does a t/d do at 60mph?
be1s are apparently much weaker than be3.
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DavidRutherford
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Post by DavidRutherford »

a TD will do about 26mph/1000rpm in top gear. ish.

As for the BE1/BE3 thing... there's almost no difference at all between the two boxes. The most obvious difference is the location of reverse (next to 1st on a BE1, next to 4th on a BE3) and the deletion of the reverse selection collar on the BE3. The gearshafts themselves are identical. I've given both BE1 and BE3 gearboxes some fairly nasty abuse over the years, and I've yet to hear one even whine a bit, never mind go wrong in any way.
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Post by CaM »

yeah I've hammered a few be3s and yet to have trouble. most have pretty big km too. even synchros seem to hold up well
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AndersDK
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Post by AndersDK »

Any BE3 box would do as spare - except for the gear ratios. The old ones should swap to new shaft no big problems - except of course you need a new (or second hand) 5.th gear.
New gears are a fortune from either Cit or peug :cry:
While you are there - select the better of the shaft bearings from both units. Or get new bearings from you local machinery shop.
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Post by Kevin B »

Thanks for all your replys, here's whats happened to date:

I have ended up with another complete gearbox from a Peugeot 1.9 TD, although this had the dreaded pull off clutch cross shaft arangements, and enough bits to repair my original gearbox plus some spares.

I stripped a number of gearboxes from scrapper engines, and this problem appears to be more prevelant than I had prevoiusly thought. As most of the gearboxes that I removed the sheet metal cover from the 5th gear cluster had either a loose 5th gear syncro hub on the main shaft or loose 5th gear on the layshaft.

Although BE1 gearbox internals look similar to BE3 gearbox internals there are subtle yet important differences ie BE1 mainshafts have a lower 1st gear ratio, and are not interchangable with the BE3 mainshaft.

However after stripping 5 scrapper gearboxes I have now ended up with two good mainshafts and syncro hubs and also the correct cross shaft to convert the pull off clutch gearbox to BX TD spec (although I suspect the ratios maybe a bit taller as it was from a 1.9 TD engine).

I have now rebuilt my original gearbox with a good mainshaft / syncro hub. Although it was a struggle I managed to rebuild it in situ without having the whole gearbox out. Removing the stud which the gearbox rubber mount secures to made it much easier. I also replaced the nuts on the end of the mainshaft and layshaft (which convieniently come in packs of two).

In light of my recent experience I will be stocking up on these items.
For future spares provisions for my 16V projects. As gearboxes fitted to 16v applications must be even more suseptable to this problem, due to the torque of the 16V engine.
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Post by jeremy »

Well done - hope it all works nicely!

The torque of the BX 16 valve is the same as the TD. The 1.9TD would be a bit greater. (1.7 TD & 16 valve 133/134 lb ft - 1.9TD 142?)
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Post by DavidRutherford »

jeremy wrote: The torque of the BX 16 valve is the same as the TD. The 1.9TD would be a bit greater. (1.7 TD & 16 valve 133/134 lb ft - 1.9TD 142?)
149 is the factory quoted figure.

But, the gear ratios are the same. Certainly the 405 1.9TD BE3 gearbox has identical ratios to a BX 17TD.
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