Finally ... Repairing a traction gearbox.

[gerrypro]

There is a major fault with Tractions gearboxes that Gerry may be able to explain better than me. But one of CCOCA's members, Bernie Hadaway ( also recently deceased ) had observed that one of the gears ( second I think ) has a sharp edge when being cut which was a modification by Citroen engineers made on the assembly line - but this undercut creates a stress point and eventually creates a weak point. Bernie had a solution which added another bronze bearing to this area which solved the design problem. I will try and find this article from CCOCA records and post it here. With the gearbox apart it would be worth considering the modification. There is also the Jack weaver strengthening plate which can be fitted internally to stop the gearbox casing cracking from within. Details of these are still available.

Over to Gerry for his thought.
Hawk
(Ted Cross)

The gears were machined with a point lead for the first /reverse sliding pinion and its matching engaging gears. It slowly becomes rounded as people clash the gears when engaging. The dog clutches on second and third idler pinions are also cut with a pointed lead to allow the splines of the synchro outer hub to lock over and engage. The break in Shanes box is very unusual as it is usually the second/reverse idler cluster on the mainshaft that breaks. It does this as of the tow sets of gears that are constantly engaged it is the smaller and therefore more highly loaded. The other factor at work is the fact that inside this cluster are two bronze bushes pressed in the bore from either end. These do not meet in the centre of the gear in order to form an oil well. Unfortunately they are prone to moving with age to close the center oil well space. This means that the gear is supported on the shaft incorrectly and can then wobble out of concentricity in relation to the mainshaft. The gear can then load up out of contact with the full face of its engaging pinion shaft gear. Point loadings and high stress occur under a shock load from the driven wheels ( ie hitting a pothole under power in second gear ) and the tooth breaks off.
It is a situation easy to rectify. Either fit new gear bushes and Loctite them in place or modify the floating bush from the pinion shaft to make a single piece bush for the second/reverse idler. It too can be loctited in and the oil supply holes drilled for lubrication. This one piece bush needs the be reduced on the OD to fit and then cut to length to match the second/reverse idler gear.
Ted I think that Bernie was 'Tilting at Windmills' with his theory.
As for the strengthening plate-----if you are going to race it OK but a properly built box is very strong with out it. The plate fixed to an improperly built box may save the case from splitting but the damage can still happen to the gears.
Of most importance is pinion shaft depth setting and assembly integrity. Throw away the multi tab washer from behind the pinion nut and ensure that the C locking rings are unmarked on the side that bears on the splines of the pinion shaft. If one side of these is worn it is permissible to turn them around the other way so that the unworn side is now providing accurate lock up when the assembly is tightened.

 

[DoubleChevron]

I'll strip the reverse/idler cluster off as soon as I have time. There IS slop there. It will be interesting to see if the bushes have moved out of position. I'll order in new bushes once I have them out (to verify the bush size, I notice the website above sells oversize bushes, machining of the bush area must be possible).

The only very obvious slop in this gearbox is the twin bushes mention above and the reverse idler shaft. I imagine the reverse idler will need shimming as opposed to a new bush though. I haven't looked closely to verify. Given the bushes are so modestly priced, it would be craziness not to replace them if there is evidence of wear.

seeya,
Shane L.

 

[JohnW]

Resin impregnated fabric ---very durable and excellent lubricity!

It's not an intuitive combination is it? But it surely works. Timing gears can last the best part of 100,000 km plus with suitable oil changes - mine in the 1951 4CV was new in 1970, at least 100,000 km ago. I've not seen it in a gearbox before, but I have led a sheltered life with the Renault transaxles. That TA gearbox is quite a sophisticated piece of work I reckon.

 

[gerrypro]

It's not an intuitive combination is it? But it surely works. Timing gears can last the best part of 100,000 km plus with suitable oil changes - mine in the 1951 4CV was new in 1970, at least 100,000 km ago. I've not seen it in a gearbox before, but I have led a sheltered life with the Renault transaxles. That TA gearbox is quite a sophisticated piece of work I reckon.

Yes Not a bad box seeing as legend has it that it was designed and built in 30 days once the Sensaud De Lavaud auto trans proved unworkable!

 

[gerrypro]

I'll strip the reverse/idler cluster off as soon as I have time. There IS slop there. It will be interesting to see if the bushes have moved out of position. I'll order in new bushes once I have them out (to verify the bush size, I notice the website above sells oversize bushes, machining of the bush area must be possible).

The only very obvious slop in this gearbox is the twin bushes mention above and the reverse idler shaft. I imagine the reverse idler will need shimming as opposed to a new bush though. I haven't looked closely to verify. Given the bushes are so modestly priced, it would be craziness not to replace them if there is evidence of wear.

seeya,
Shane L.

The reverse idler end thrust bearings are supported by that bit of casing that is broken off! Are you sure you do not wish to use my spare casing? After all the stuff you have done for me and my CX there would be no charge for the parts!!!!! I am happy to donate them to a worthwhile cause like your TA.

 

[AllenM]

Gerry that is a very generous offer on your part and I would urge Shane to take it up.
I recently saw a gearbox that had been rebuilt by a gearbox specialist (not Citroen) where the bush had turned in the 2/3 gear, thus cutting of the oil supply and as a result blew the bottom out of the box. I can't read a word of this post: Modifikation 2. Gangrad Traction Avant Getriebe but the pictures tell the story and I believe it would be a worthwhile modification. Shane you might save a dollar here Gearbox: Gears . These people are reliable and easy to deal with.
Cheers AllenM

 

[Andrew Watkins]

Traction gearbox. Translation of German text

Have translated the big block of text on this link. Please forgive me if my technical German is not wholly up to scratch.

"
The second gear wheel in the Traction gearbox has driven many to distraction, myself also.

In a rebuild of the gearbox, according to the handbook, the 2nd gear should be replaced if its inner is conical/tapered. This is most of them. Both bronze bushes are pressed in and there is a space between them to hold lubricant. If conical/tapered the smaller of the bushes can butt up against the larger, blocking the oil hole, the bush wears out quickly and one is on the slippery slope. Everything has to start again from the start - box out and dismantle.

One of my predecessors had solved this problem with a one piece bush. This had then rotated and blocked the oil hole. Another had then tried the original solution with the same result.

I've chosen a simple and safe solution for this.

A small distance ring protects the oil supply permanently. The bushes can neither push up against each other nor rotate and block the oil hole because of a spiral lubrication groove on the outside.

Incidentally: I have made the bronze bushes with the counterthreaded lubrication groove out of tough bronze. There used to be smart-arses who used unsuitable alloys or even brass as bearing material. In addition I also ground out the second gear wheel to be truly cylindrical.

Overkill is better."

Best Wishes

Andrew

Gerry that is a very generous offer on your part and I would urge Shane to take it up.
I recently saw a gearbox that had been rebuilt by a gearbox specialist (not Citroen) where the bush had turned in the 2/3 gear, thus cutting of the oil supply and as a result blew the bottom out of the box. I can't read a word of this post: Modifikation 2. Gangrad Traction Avant Getriebe but the pictures tell the story and I believe it would be a worthwhile modification. Shane you might save a dollar here Gearbox: Gears . These people are reliable and easy to deal with.
Cheers AllenM

 

[gerrypro]

Andrew. Phosphor bronze bushes are the only way to go. As I have said I modify the floating bush from the lower ( pinion ) shaft. A small groove cut in the OD in line with the oil supply holes makes sure that the oil holes can never block if the bush does happen to rotate. The original style bushes if Loctited will never move. The information in the workshop manual about reclaiming second gear pinions can be ignored as it is overly pedantic!

http://www.tractionavant.ch/Berichte/Technik/Getriebe/Modifikation2Gang.php

The solution here is also brilliant. Shane you have a lathe!

 

[DoubleChevron]

Ok, the last bit to come off...

I'm glad I have a manual here... I would have tried to tap that through/out with a punch and hammer. Manual says "push in with a screwdriver so you can rotate the collar".

Gee's how lucky am I .... That didn't shoot across the shed ... Usually I find the spring loaded stuff by the sounds of the bits bouncing off the shed walls.

The gear just lifts off ... and look at that, yet again, Gerry is correct. See the shiny bronze rather than a dark oil feed hole.

The front bush has moved.

I really don't see the wear that is being spoken off

This looks really poorly cast at the factory, with one corner broken away. I'd have thought it fine given there is a shim beside it to spread out load The load of the gears will only ever push the shaft towards the out case, not suck in in against the open front

So I'll order in two new bushes.... And fabricate one of these out of a section of one of the worn bushes as suggested by Gerry.

seeya
Shane L.

 

[gerrypro]

I have never seen a case broken at that point before Shane. There is really not enough material there to adequately support the front thrust washer.
BTW did I tell you about the inner thrust rings on the reverse idler that can be reverse fitted so that the balls have a new surface to run against? They just tap out easily.
The fun and games start when you try to reassemble that plunger dowel and lock ring! I find that a piece of hard wire bent at right angles so that the bent leg is the space between the thrust recess of the gear and the bottom of the spline on the mainshaft will hold the dowel depressed until the lock washer can be slid down and partly retain the dowel. The wire can be twisted out and the lock ring turned until the dowel snaps into place! Good Luck!

 

[Whippet]

Hi - I suspect that the problem is caused more by the blocking of the lubrication thus causing accelerated wear of the bush, than the bush not supporting the adjacent gears. Yes the bush has moved in a little, but the smaller OD outer gear is still supported outboard of the extents of the gear teeth. Just thinking aloud...

 

[gerrypro]

Hi - I suspect that the problem is caused more by the blocking of the lubrication thus causing accelerated wear of the bush, than the bush not supporting the adjacent gears. Yes the bush has moved in a little, but the smaller OD outer gear is still supported outboard of the extents of the gear teeth. Just thinking aloud...

Yes the displaced bush blocks the lubrication holes And the bushes begin to wear in a bell mouth situation!

 

[DoubleChevron]

Well I'm incredibly lucky. Gerrypro called in for a visit last month. He spotted quite a few issues I had missed. I'll go into these as I get to them (so he can correct me if I'm wrong ).

This is why Gerry was so concerned I couldn't use that gearbox case. There is actually a whole chunk missing. The bizare bit? It's not in the gearbox anywhere! I wonder if this was broken off many decades ago and ignored

I did go fishing .... and foudn the broken teeth.... But where is the broken bit of gearbox housing

 

[DoubleChevron]

This should make life easier. The car has come down here for a holiday (this car has done more kilometers on my car trailer than it has under it's own power :roflmao: ).

I imagine this will be it's new home for sometime. no doubt it'll take me to next spring to get the gearbox together and back in ( there is a lot of stuff I need to do that has priority over it .... ).

I couldn't help myself though, I had to crawl under it ... I've never really seen under this car before. Infront of the back wheel. I have no idea if this is right. It doesn't look rusty though.

The boot. A decent hole in the bottom of it. It looks like large drain slot cut into it ................. Or a nicely shaped rust hole.

same deal above the other back wheel.... bodged up .... or how it left the factory knowing Citroen. how on earth it hasn't rusted out here I don't know with those overlapping kinda joined together pieces. (they did a lot of that on the DS hull too).

Er, I rekcon I might re-route those fuel tank sender wires .... I don't reckon the exhaust is the best place for them ( Oh, and no wonder is sounds so nice, that looks like a brand new Lukey muffler there). It's hard to believe this car is 65years old .... It's way less rusty than any other car I own by the looks of it! The floor pan looks fantastic (either that or I have no idea how to check Tractions, which is entirely possible )

Qualtrim in Ballart retrimmed this car about 15years ago. I know it's not original. But I reckon it looks spectacular.... The did a brilliant job of it. They used those stainless steel headed nails to assemble all the roof lining and everything. It looks and smells new inside. I don't like even sitting in it for fear of messing it up (all my cars are "well used family" cars... ie: covered in kids crap, stains, dirt and holes).

Yes, it was on a club permit years ago..... Just as well it was that really crappy club permit scheme that didn't allow you to ever actually drive the car .... As that gearbox sure would have exploded. The only trip this car ever did was a drive ... maybe 10km round trip to be my wedding car.

seeya,
Shane L.

 

[caparobertsan]

Very nice looking car! Jealous!

 

[gerrypro]

Yes This car is really nice! Once the gear box is back together and those few rust issues( very very few!) are attended to she will be good to go for many more miles.
You should have seen the amount of rust I had to contend with around the boot floor and fuel tank area on my11BL. Basically I had to replace the bottom six inches of the whole rear and remanufacture hinge plates and captive nuts /retaining plates for the boot lid! Lots of fun when all you have is a set of dollys a few panel hammers and a length of six inch I beam steel as your specialist work tools

 

[gerrypro]

Well I'm incredibly lucky. Gerrypro called in for a visit last month. He spotted quite a few issues I had missed. I'll go into these as I get to them (so he can correct me if I'm wrong ).


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This is why Gerry was so concerned I couldn't use that gearbox case. There is actually a whole chunk missing. The bizare bit? It's not in the gearbox anywhere! I wonder if this was broken off many decades ago and ignored

I did go fishing .... and foudn the broken teeth.... But where is the broken bit of gearbox housing

Pulverised to paste between the remaining gears! Notice how golden your oil sludge is! It is usually a dark grey!

 

[DoubleChevron]

Pulverised to paste between the remaining gears! Notice how golden your oil sludge is! It is usually a dark grey!

That's a possibility! As for rust ... that doesn't look like rust damage. maybe it's accident repair Though both sides are the same. Did you notice there is no wind up vent in the scuttle I think one of the reasons for lack of rust is the scuttle was obviously leaded shut when the car was quite new, so it's never had water leaks into the front floors. The flap and assembly is all still there if you look up from under the dash though. I imagine if anyone wanted it back, they could melt some lead and the flap will re-appear.

seeya,
Shane L.

 

[DoubleChevron]

When Gerry had a look at these bits... He picked stuff right away.... it took him about 3minutes to find everything I hadn't noticed:

One of those broken teeth has obviously gone through the crown and pinion.... It's a miracle it shatter the gearbox case. Yes I'd missed this. Note: the damaged hardening (luckily not really in a wear area).

See the marks in the C shims where the shaft has been rocking ....

Fortunately he also reminded me I'd need seals .... Lets hope they work. The old Renault 12 had a similar seal ...they were miserable bloody things that always leaked on me. It doesn't look like the existing seals leek though (I don't consider "weeping" leaking though ).

I also ordered in the missing key way.

Anyway, I thought I'd start by making this up....

the bushes are exactly 22mm long. The depth of the area in the gear appears to be 48mm.,, so the spacer needs to be 4mm wide.... I wanted to double check this though.

The bloody hole isn't centred. If I make that spacer as shown above, I'll block at least 50% of the oiling hole off. What I'll need to do is turn one of the new bushes down by 2mm and make the spacer 2mm wider so it's centred over the oil hole.

I wonder why the oil hole is off center? Very weird.

Oh, and the one thing I found "wrong" with this gearbox that I thought would need repair ... Doesn't. That is the slop in the reverse idler shaft.

This is where the bearings have run against the spacers for the last 60years....

It looks like just turning the shims around as suggested by Gerry will remove all the slop.


seeya,
Shane L.

 

[gerrypro]

Don't forget to reverse the thrust rings in the end bore of the reverse idlers as well as the large thrust rings!!!!!!!!!!!!
Bed the outer parts of those large seals with silicone sealant, and use 'Speedie Sleeves' to rebuild the seal run of the output flanges!