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Author Topic: Mechanical challenges  (Read 9377 times)
Jon Weywadt
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« Reply #15 on: July 26, 2009, 05:54:24 pm »

Hi Jon

Congratulations on finding that problem - and fixing it. Regarding the rubber boot, I had the same experience and took it off. It was never on the early gearboxes, but is a later upgrade for another car, I think.

/Anders
Hi Anders.

Well, it turned out not to be fixed completely. 1./2. gear works fine (except the 2. gear synchro is a bit weak and requires a gentle shift), but 5./R. was now difficult.  Sad

I determined that the problem is twofold. One, the rubber boot I put on the shifter rod is limiting the downward movement, but only slightly. Two, there is a good bit of lateral flex in the shifter tube that runs from the gear shifter to the back pivot point. Because of the bend at the back of the tube it causes the bracket on the middle of the tube to pivot around its center, resulting in only 3 cm of movement side to side. It is enough to transfer the up/down movement of the shifter rod, except for the flexing of the tube. The previous owner had made a jury-rig with a steel band, but I put a plastic sleve over the tube and made a bracket that allows the tube to move freely back and forth and pivot, but not flex side to side.
Also, I had not been able to remove all the air from the clutch slave cylinder, so I had to pump the pedal to get disengage the clutch.

All problems have finally been taken care of and it now shifts fine.  Grin Grin Grin
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Matra_Hans
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Owner of Bagheera, Rancho, Murena & Espace


« Reply #16 on: July 26, 2009, 06:45:18 pm »

Hi
I have actualymade a similar support to my gear shift some years back, and I can confirm the it improved the shift very much.

Hans
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michaltalbot
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« Reply #17 on: July 27, 2009, 09:43:28 pm »

I was thinking about the same solution as on Your picture Jon, when we bought yellow 1,6 for my Maria. There was a "classic" problem - when was possible to gear 1st and 2nd than was problem with reverse and oposite. The shifting bar was moving from side to side, but not turning as it had to. Than I was doing something on my 2,2 S and one of operations was demounting the small shift bar ( letter "D" on Anders picture)

Than I did what I wanted and went for test drive - from that moment I had problems with gearing 1st and 2nd gear. Why to hell? I meditated where could be the reason, and remembered that only one thing, arround gear linkage, which I  touched was the bar "B", arm "A" and small bar "D".
I found that problem is as follows - when I demount the small bar "D" from joint on arm "A" usually I do it by some lever (red on my picture)

when moving it in sense of red arrow. And that's the problem, because at this moment the arm  "A" bends a little in sense of green arrow and later it works wrong. When I found this, I've bent arm "A" in oposite sense and my gearing was perfect again - wow! I immediatelly went to our garage and bent arm "A" also on 1,6 and believe it or not, from that moment it gears perfectly!
It's very simple but maybe this is a gear problem on your Murenas  Wink
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Jon Weywadt
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« Reply #18 on: July 28, 2009, 10:58:02 am »

----- And that's the problem, because at this moment the arm  "A" bends a little in sense of green arrow and later it works wrong. When I found this, I've bent arm "A" in oposite sense and my gearing was perfect again - wow! I immediatelly went to our garage and bent arm "A" also on 1,6 and believe it or not, from that moment it gears perfectly!
It's very simple but maybe this is a gear problem on your Murenas  Wink

I will probably try your solution to the problem. As I understand, you straighten out arm "A" on the picture, so that it is more of a right angle with the tube "B". This will make the end of "A" move further, since its length with respect to the pivot point becomes longer.

I have tried to see if the links (K, D & F) have been put in the wrong places, because there is not enough thread on one or two of them to adjust their length, so that "A" is straight up, and "J" straight forward, when in neutral. Swapping them around does not seem to help, so I am interested if anyone knows what length they should have when they are perfectly adjusted?

Update.
While analysing how the links work and trying to discover what is wrong, I discovered that the pivot point ("I" on Anders' drawing) may be the wrong type. It is not a ball and snap-on socket, like the others and as shown on the drawing, but a ring with an imbedded ball with a hole through.

This has a limited range of motion, since the ring hits the bolt or the bracket when twisted. I put some shims under it, so it could not touch the bracket when moving the gear shifter side to side. But it may not  be enough. I will have to get an original type and see if that helps.

Another possibility is that the bend in the tube "B" is too big, causing the the pivot axis to be through the center of arm "A". If this bend is straightened out some, the axis will move to the bottom of arm "A", thereby increasing the range of movement at its tip. There is 6 cm clearance under the engine to the tube, so it can be straightened out some, though not perfectly straight.
« Last Edit: July 28, 2009, 11:27:43 am by Jon Weywadt » Logged

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« Reply #19 on: July 28, 2009, 12:49:18 pm »


Another possibility is that the bend in the tube "B" is too big, causing the the pivot axis to be through the center of arm "A". If this bend is straightened out some, the axis will move to the bottom of arm "A", thereby increasing the range of movement at its tip. There is 6 cm clearance under the engine to the tube, so it can be straightened out some, though not perfectly straight.

Yes, this also could be the reason, but it's not easy to bend the tube "B", but try to straighten arm "A" a little and You will see how easy it is  Shocked with good lever You can straighten it with very low power... And on Anders picture the angle between arm "A" and tube "B" is much bigger than it was on both our cars. Than arm "A" and small bar "D" and transducer "E" are in wrong positions to each others and also in wrong angles and it could be the cause of that You need more power to insert the gears and result is that tube "B" goes from side to side.
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Jon Weywadt
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« Reply #20 on: August 01, 2009, 08:26:00 pm »

Hi Michael.

I followed your advice and straightened the center arm "A" so the angle is about half what it was. That made the motion at the tip a lot longer, since the tip is now 3-4 cm further from the pivot axis. I also tried to straighten the tube out, but had to give up. I got it a tiny bit straighter, but it was threatening to flatten the tube near the bend, so I quit that.

I also looked at the link between the gear shifter and hte tube. There was a good bit of play due to wear of the bushing. I made some shims out of a sheet of teflon and cut a strip that I wound arounf the bushing before inserting it into the gear shifter. With that and the shims, there is almost no more play and thus the gear shifter twists the tube as much as is possible.

I also adjusted all the links so the brackets "J" and "E" now are straight front/back when in neutral.

With all this, the gears now shift perfectly and I did not reinstall the bracket that I had previously placed around the tube. It was not necessary.  Grin
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« Reply #21 on: August 01, 2009, 08:57:43 pm »


With all this, the gears now shift perfectly and I did not reinstall the bracket that I had previously placed around the tube. It was not necessary.  Grin

So, if I understood well, my extra simple solution works on Your car too  Grin

Lot of people are doing complicated repairs of gearbox, etc. and only two things, which are solving the problem, are cleaning + greasing the transducer "E" and straightening the arm "A"  Cheesy
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Jon Weywadt
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« Reply #22 on: August 05, 2009, 09:10:33 am »


--- So, if I understood well, my extra simple solution works on Your car too  Grin
---
Indeed it did, and thanks. It was a simple fix.  Smiley

A few annoying issues remain.
First. The nylon ball on the gear shifter is worn, so there is too much play and it feels loose. This does not give a precise feel when shifting gears. Simons want 130€ for that piece of the gear shifter alone.  Angry I think that is pretty steep, so I will either machine a new piece myself, or cast a new nylon ball on the old one. There are several Devcon products that should work nicely. I will have to turn it on a lathe with a cutting tool that has the right curve, since I do not have access to a sphere turning tool.

Second, The synchro ring for the 2. gear is worn and does not allow for a swift gear change. I may have three options. 1. Have the old ring chromed and polished to add a small amount of thickness to it (Jan's suggestion). 2. I seem to remember that this ring was known for wearing out too soon and repairs could be made by shaving a small amount off the ring on the side that faces the gear. This would allow it to move closer to the gear and thus seating properly on the synchro cone on the gear wheel. 3. Buy a new ring, if that is still possible.  Huh

If anyone has faced the same problems, how did you fix them, or have you just learned to live with them, seeing as it IS an old car?  Wink
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suffolkpete
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« Reply #23 on: August 05, 2009, 03:06:30 pm »

The nylon ball is prone to wearing.  When I bought my car it was so worn that no gears could be selected.  I took the cup apart by splitting it into two halves and shaving some material off the face and then placing some packing material underneath it to take up the play.  There is still some play though, making gear selection a bit random, so I would be interested to hear of any better solution.
I also had the same second gear synchro problem.  This is due to the gear being machined incorrectly so that the synchro doesn't engage properly.  Changing the synchro alone won't produce a permanent cure, the gear needs to be replaced or machined as well, though I replaced the gearbox with a good second hand one. as it seemed an easier option.  Maybe one of those Citroen gearboxes being dismantled for the high fifth gear would have the right bits.
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