2CV Gearbox question
- Thread starter pottsy
- Start date
The dipstick is my own creation.
The hole is clearly visible in the second pic in the first post.
Car is notionally a 1979, but anyone's guess as to which bits!
Cheers, Pottsy
The hole is clearly visible in the second pic in the first post.
Car is notionally a 1979, but anyone's guess as to which bits!
Cheers, Pottsy
OK, time for an update perhaps.
Not being able to find anything obviously wrong with the box of cogs, apart from the aforementioned hole and seals, I put it all back together with a fresh lot of oil and crossed my fingers.
Strangely, the synchro into 3rd seemed fine at first, but occasionally would be defeated after a goodly rev in second, say, for a hill. Also seemed to only happen occasionally after a longish run, which may indicate the oil heating up? I just don't know.
In any case, off to Tasmania we went, the three of us, Gaston, myself and the wonderful Mrs P.
1400 odometered (and relaxing) miles around Tasmania was accomplished with no fuss, but fairly consistent reluctance on the part of 3rd gear synchro. I'm now adept at double shuffling again, a skill I haven't really needed in my Frenchies!
So after arriving home from Tassie, up on the rack went Gaston, out came his vital fluids and off came the top of the gearbox.
Nothing obvious once again. The box wasn't leaking like before. A regular poke of the breather hole had ensured it stayed clear. The oil contained no nasties and neither were there any down the bottom of the casing when I went fishing with a magnet. On advice from the Viking I checked the assistance spring was present, it was, and then decided to double check the clearance setting of the selector fork. I don't think it was out, but it's definitely now set to 1.8mm with my home made version of tool 1786-T. (also home brew version of MR630-64/21 in place holding the detent spring).
A fill with Castrol VMX80 and NulonG70, seal the top with Loctite 515 and off the rack and on to the road. (Not forgetting the engine oil and filter!)
Results are mixed. The first 20 or 30 shifts in to 3rd were silky, seamless and crunch free. Pat on the back, but premature. After a while, perhaps once the VMCX80 was warmed, the crunch would occasionally happen again, albeit not as often.
So I'm slowly coming to the unwelcome realisation that maybe my 3rd gear synchroniser is cactus, or at least reluctant to serve its purpose consistently.
Time to look closely at my spare box bits. I have a short spline one but until I do some tooth counting I can't be sure its bits will serve as replacements, or if indeed they're serviceable.
Time will tell. Cheers, Pottsy
Not being able to find anything obviously wrong with the box of cogs, apart from the aforementioned hole and seals, I put it all back together with a fresh lot of oil and crossed my fingers.
Strangely, the synchro into 3rd seemed fine at first, but occasionally would be defeated after a goodly rev in second, say, for a hill. Also seemed to only happen occasionally after a longish run, which may indicate the oil heating up? I just don't know.
In any case, off to Tasmania we went, the three of us, Gaston, myself and the wonderful Mrs P.
1400 odometered (and relaxing) miles around Tasmania was accomplished with no fuss, but fairly consistent reluctance on the part of 3rd gear synchro. I'm now adept at double shuffling again, a skill I haven't really needed in my Frenchies!
So after arriving home from Tassie, up on the rack went Gaston, out came his vital fluids and off came the top of the gearbox.
Nothing obvious once again. The box wasn't leaking like before. A regular poke of the breather hole had ensured it stayed clear. The oil contained no nasties and neither were there any down the bottom of the casing when I went fishing with a magnet. On advice from the Viking I checked the assistance spring was present, it was, and then decided to double check the clearance setting of the selector fork. I don't think it was out, but it's definitely now set to 1.8mm with my home made version of tool 1786-T. (also home brew version of MR630-64/21 in place holding the detent spring).
A fill with Castrol VMX80 and NulonG70, seal the top with Loctite 515 and off the rack and on to the road. (Not forgetting the engine oil and filter!)
Results are mixed. The first 20 or 30 shifts in to 3rd were silky, seamless and crunch free. Pat on the back, but premature. After a while, perhaps once the VMCX80 was warmed, the crunch would occasionally happen again, albeit not as often.
So I'm slowly coming to the unwelcome realisation that maybe my 3rd gear synchroniser is cactus, or at least reluctant to serve its purpose consistently.
Time to look closely at my spare box bits. I have a short spline one but until I do some tooth counting I can't be sure its bits will serve as replacements, or if indeed they're serviceable.
Time will tell. Cheers, Pottsy
An update to the Update. FIGJAM!
Having explored the spare gearbox a little, to the extent of dismantling and re-mantling it to re-educate the muscle between the ears, I feel way more knowledgeable about these speed matching devices in our 2CVs.
My apologies if this post gets a bit wordy and convoluted. This is not a simple mechanism, despite being in a 2CV. Damn clever those Froggy Chaps!
With digital mentoring from Peter of the Viking persuasion (thanks mate), I focused on the jiggers that Burtons call "gearbox snap rings" and DerFranzose call "gearbox check rings". These are a cunning bit of design that, sort of, pre-load the synchronising ring in each of the gears. This is achieved by the snap ring being a tight sliding fit within the synchro ring thus pushing it gently into engagement before the incoming gear dogs brutally push it the rest of the way, forcing it to match the speeds on the journey. If this pre-loading taketh place not, then the brutally forced dogs will crunch before finally engaging as the bronze synchroniser ring isn't pressed gently in to the spinny bits enough.. This is simpler to understand with the gears in one's hand, but I think I've conveyed the gist.
In any case, these rings are relatively thin so that the resistance they exert is only enough to facilitate the synchronisation process. A close inspection of those in my spare gearbox revealed that they were worn by a small percentage of the overall thickness, enough, perhaps to reduce the braking effect on engagement.
So having obtained a couple of sets of the rings, 2x29.5mm dia for 2nd & 3rd gears, and a 32mm one for 4th. I decided on a Cunning Strategy of replacing them in the spare gearbox before thinking about tackling the one in the car. I'm reluctant to use this box in the car as it's a "short spline" version wherein the spline that engages in the clutch driven plate is shorter than the usual unit. I think these boxes are for Trafficlutch cars but I'm prepared to be corrected. In any case, apart from the spline length, the internals are the same so I dismantled the whole thing to suss out the check rings. The 2nd and 3rd gear units showed definite signs of wear, but strangely the 4th gear unit was pristine.
Having adjusted and reassembled the Spare to my satisfaction (eventually) I decided the time had come to disembowel the Amazing Gaston and suss his box of cogs once and for all. So last Monday out it all came. Once on the bench in the nice, air-conditioned, shed I could dismantle and inspect in comfort. My reasoning was that if the existing box showed no signs of distress at all then Plan B was to attach the Spare and see how it went.
Now being adept at disassembly it took no time to have it all laid out on the bench and the wear on the 2nd and 3rd gear rings mirrored that of the spare box. Back in 2017 when I was building Gaston I treated the gearbox to all new bearings and new intermediate shaft. At the time I was ignorant of these magic rings, but to be fair, the box did Raid NZ and the Katanning Cit-In without any complaint, so perhaps they were OK at the time. It was only relatively recently, as detailed in the previous posts of this topic, that 3rd began to complain about "coming together like Mummies and Daddies".
Since the bearings, cogs and shaftes are all still excellent, the decision was made to simply replace the rings in this box with new ones, re-assemble and "suck it and see".
So yesterday Gaston was re-embowelled. All the final bolts were fitted and tightened. A pair of broken exhaust hangers were replaced with new ones hand-crafted from some 6mm insertion rubber, the brakes bled and the panels returned to their normal positions. A fill of the gearbox with some very expensive Penrite GL-4 ProGear synthetic gooey stuff and we were ready for a test run.
Today, after an fairly exhaustive test drive, I'm cautiously optimistic that my crunching days are in the past. Gear synchronisation is now seamless, rapid and unbeatable, no matter how fast the whirling inside the casing. I'm taking that as a win!
So the lesson from this, Kiddies, is that sometimes the simplest little bits of a complex mechanism can bite you on the arse!
Herewith a couple of pretty pics to augment your puzzlement! First diagram, borrowed from Burtons website, showing the placing of the 3 rings, second a closeup of worn ones, and a worn 2nd gear unit in situ.
I now declare myself to be Lord of the Rings!
Having explored the spare gearbox a little, to the extent of dismantling and re-mantling it to re-educate the muscle between the ears, I feel way more knowledgeable about these speed matching devices in our 2CVs.
My apologies if this post gets a bit wordy and convoluted. This is not a simple mechanism, despite being in a 2CV. Damn clever those Froggy Chaps!
With digital mentoring from Peter of the Viking persuasion (thanks mate), I focused on the jiggers that Burtons call "gearbox snap rings" and DerFranzose call "gearbox check rings". These are a cunning bit of design that, sort of, pre-load the synchronising ring in each of the gears. This is achieved by the snap ring being a tight sliding fit within the synchro ring thus pushing it gently into engagement before the incoming gear dogs brutally push it the rest of the way, forcing it to match the speeds on the journey. If this pre-loading taketh place not, then the brutally forced dogs will crunch before finally engaging as the bronze synchroniser ring isn't pressed gently in to the spinny bits enough.. This is simpler to understand with the gears in one's hand, but I think I've conveyed the gist.
In any case, these rings are relatively thin so that the resistance they exert is only enough to facilitate the synchronisation process. A close inspection of those in my spare gearbox revealed that they were worn by a small percentage of the overall thickness, enough, perhaps to reduce the braking effect on engagement.
So having obtained a couple of sets of the rings, 2x29.5mm dia for 2nd & 3rd gears, and a 32mm one for 4th. I decided on a Cunning Strategy of replacing them in the spare gearbox before thinking about tackling the one in the car. I'm reluctant to use this box in the car as it's a "short spline" version wherein the spline that engages in the clutch driven plate is shorter than the usual unit. I think these boxes are for Trafficlutch cars but I'm prepared to be corrected. In any case, apart from the spline length, the internals are the same so I dismantled the whole thing to suss out the check rings. The 2nd and 3rd gear units showed definite signs of wear, but strangely the 4th gear unit was pristine.
Having adjusted and reassembled the Spare to my satisfaction (eventually) I decided the time had come to disembowel the Amazing Gaston and suss his box of cogs once and for all. So last Monday out it all came. Once on the bench in the nice, air-conditioned, shed I could dismantle and inspect in comfort. My reasoning was that if the existing box showed no signs of distress at all then Plan B was to attach the Spare and see how it went.
Now being adept at disassembly it took no time to have it all laid out on the bench and the wear on the 2nd and 3rd gear rings mirrored that of the spare box. Back in 2017 when I was building Gaston I treated the gearbox to all new bearings and new intermediate shaft. At the time I was ignorant of these magic rings, but to be fair, the box did Raid NZ and the Katanning Cit-In without any complaint, so perhaps they were OK at the time. It was only relatively recently, as detailed in the previous posts of this topic, that 3rd began to complain about "coming together like Mummies and Daddies".
Since the bearings, cogs and shaftes are all still excellent, the decision was made to simply replace the rings in this box with new ones, re-assemble and "suck it and see".
So yesterday Gaston was re-embowelled. All the final bolts were fitted and tightened. A pair of broken exhaust hangers were replaced with new ones hand-crafted from some 6mm insertion rubber, the brakes bled and the panels returned to their normal positions. A fill of the gearbox with some very expensive Penrite GL-4 ProGear synthetic gooey stuff and we were ready for a test run.
Today, after an fairly exhaustive test drive, I'm cautiously optimistic that my crunching days are in the past. Gear synchronisation is now seamless, rapid and unbeatable, no matter how fast the whirling inside the casing. I'm taking that as a win!
So the lesson from this, Kiddies, is that sometimes the simplest little bits of a complex mechanism can bite you on the arse!
Herewith a couple of pretty pics to augment your puzzlement! First diagram, borrowed from Burtons website, showing the placing of the 3 rings, second a closeup of worn ones, and a worn 2nd gear unit in situ.
I now declare myself to be Lord of the Rings!
Attachments
Hi Pottsy,
I am thinking you are justified in having impressed your self on this one.
I wonder how many people over the years have given up on (seemingly) intractable syncho problems because of this issue?
Cheers,
Andrew
I am thinking you are justified in having impressed your self on this one.
I wonder how many people over the years have given up on (seemingly) intractable syncho problems because of this issue?
Cheers,
Andrew