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Anders Dinsen
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« Reply #16 on: October 03, 2009, 05:33:02 pm » |
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Hi Graham Your modification is neatly made, but it must be working against the geometry of the gear linkage. As your photos also show, rod B is not straight, so by fixing it like you have done, something will have to "give" when you move the gear lever from side the side. Only if your fixture was vertically in line with the line going from the gear lever pivot point and the pivot point of joint I, it would work without "give". I have done a bit of editing on the linkage drawing. I'm not sure about the actual length of the rod B, but this should illustrate the problem. The red dashed line is the line around which the rod swings from side to side, and either ends of that are (supposed to be) fixed. With your modification, either the rod is bending, or one or both of the joints are be loose. Regarding your "quick shift" modification - it sounds like a good and simple idea. I think the easiest way to implement it would be to drill two extra holes a few cm apart on arm G and weld-in nuts on the rear where you can fit custom (longer) links K. I think you would have to experiement to get the desired effect. /Anders
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1982 Talbot Matra Murena 2.2 prep 142 (under restoration) 2017 BMW i3 "Charged Professional" 94Ah 2024 VW id.buzz Pro
Used to own: 2001 Renault Matra Grand Espace "The Race" V6 24v 1997 Renault Matra Espace 2.0 8V 1987 Renault Matra Espace J11 2.2
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Jon Weywadt
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« Reply #17 on: October 03, 2009, 05:37:47 pm » |
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Hi all, A vey old topic I know, but I thought as no pictures were ever provided of gear linkage modifications, I would attach some of the very simple modification I did some years ago to my standard gear linkage. (Having serviced and adjusted the linkage for optimum performance first!) N.B. If you do not have the lower "Cross Brace" fitted to your car, obviously you cannot carry out this modification. I utilised an E.O. 22mm Gr3PP Plastic Pipe Clamp (Available in any good Norwegian Shipyard when the storekeeper is not looking ) The 22mm plastic hole was drilled out to 25mm + to give a loose fit around "Rod B". Two 6mm holes 33mm apart were drilled centrally in the cut out in the "Cross Brace" above "Rod B". The assembly was then fitted around "Rod B" with a good application of grease and bolted to the "Cross Brace" with longer M6 x 60mm bolts and nyloc nuts. It had great effect in minimising sloppiness and firming up the gear lever operation. -- -- Cheers, Graham Hi Graham. Check out the topic that I started on mechanical challenges. http://www.matrasport.dk/forum/index.php/topic,1358.0.htmlBy reducing the angle on the arm "A" to half of what it was, I got more lateral movement of the linkage for the same amount of lateral movement of the gear shifter. Reducing the length of arm "G" will do the same for forward/backward motion.
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Matranaut par excellence
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GP
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« Reply #19 on: October 04, 2009, 11:18:29 am » |
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Hi all,
Anders, yes I agree absolutely with you, it does work against the geometry as your red line indicates clearly. You have to spring the "Rod B" into the clamp if not in the neutral gate position. The "Rod B" does though flex easily though between the gear lever position and the fixed clamp position as you change gear.
The parallel in line position of "Rod B" at the fixed clamp as it goes forward and aft and rotates, just seemed to make a vast improvement to my set up. This has given me a very crisp precise gear change, which in sprints and hill limbs has been greatly to my liking. ----------------------------------------------------------------------------------------------- Jon, thanks for the link to the "Mechanical Challenges" which I was unaware of and the advice. Very good information indeed which I will use. ----------------------------------------------------------------------------------------------- Titus, sorry I will not be attending the Wobbly Wheel meeting. But if Richard is there, I would appreciate some closer inspection and information. -----------------------------------------------------------------------------------------------
Cheers,
Graham
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« Last Edit: October 04, 2009, 11:21:34 am by GP »
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GP
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« Reply #21 on: October 04, 2009, 03:54:24 pm » |
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Hi Anders,
I like that idea a lot. It seems to be a very good and simple development to my half baked effort. I will look around for a suitable U.J. and try it out. -------------------------------------------------------------------------------------------------
Hi Krede,
How about you trying this out, before going for the more complicated cable solution and giving us a second opinion?
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All the best,
Graham
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Anders Dinsen
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« Reply #22 on: October 04, 2009, 04:25:23 pm » |
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I like that idea a lot. It seems to be a very good and simple development to my half baked effort. I will look around for a suitable U.J. and try it out.
I like it too I have been thinking about something like this for years, never able to find a solution - but now it just seems to be there! Car Builder Solutions have a nice UJ: http://www.cbsonline.co.uk/gear-linkage-universal-joint-ujg-922-p.aspNote, that the rear rod piece needs to be straight for this to work, so while the front part can be made with a shortened old rod, the rear will have to be made with a new one. So it might be better to renew both. The change will cause the gearstick to rotate slightly more around its own axis than it does with the original system, but I don't think that's going to cause any problems. Don't forget to check the top bush in the gearbox, Graham. It's often worn and allows quite a bit of rocking of the rod down the gearbox. How about you trying this out, before going for the more complicated cable solution and giving us a second opinion?
I agree, the cable solution is going to be far more complicated, and I think this will be just as good. Cable is preferred on many new cars because it's cheap. /Anders
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1982 Talbot Matra Murena 2.2 prep 142 (under restoration) 2017 BMW i3 "Charged Professional" 94Ah 2024 VW id.buzz Pro
Used to own: 2001 Renault Matra Grand Espace "The Race" V6 24v 1997 Renault Matra Espace 2.0 8V 1987 Renault Matra Espace J11 2.2
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GP
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« Reply #23 on: October 04, 2009, 07:42:31 pm » |
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Hi Anders, A perfect choice for me. The 22mm diameter of this U.J. should fit inside “Rod B” with a slight reduction on the lathe. I will fit the Neoprene Boot also. Car Builder Solutions is just down the road from me. I think I'll treat the girlfriend to a nice innocuous drive out to the countryside on Monday. (She has been there before, usually via Maidstone Machine Mart!) All the best, Graham
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Anders Dinsen
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« Reply #26 on: October 04, 2009, 09:15:27 pm » |
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Hmmm, trying to reduce the sloppy gear change by introducing yet another link???
Yes, but not just a link - also the fixture of the rod. The sloppyness is due to several factors. Worn parts being just one of them, but even when restored to perfect condition, the gearchange is not very precise in the lateral movement. The reason is that even a very small amount of flexing of the rod will allow for a lot of movement on the gearstick. And since the rod is just soft iron, it bends easily. A rod like that is best for transmitting rotation and longitudal movement. By fixing the rod in the middle like Graham has done, he has prevented any flexing of the rod on the middle. It can only slide and rotate. This is a modification of the way the original system works, where the rod rotates AND swings from side to side. He also moves the pivot point of the arm A down to the rod itself instead of around the middle of it, thereby "amplifying" the motion of the gear lever's movement from side to side. Since Graham's car is race prepared, I am sure that is a desired effect. The fact that Graham has made this system work at all without the link in the middle of the rod shows how much the long rod actually flexes! A high quality UJ link in the middle will not cause any additional play in the system - these types of joints have been used for years on race cars, where you wouldn't tolerate any play. Car Builder Solutions is just down the road from me. I think I'll treat the girlfriend to a nice innocuous drive out to the countryside on Monday. (She has been there before, usually via Maidstone Machine Mart!) Lucky you! I would love to visit that shop one day - they have a lot of great stuff! Enjoy! My third option involves a more complex solution, replacing the ball with a gimball assembly. If that is possible it should be much less susceptible to the wear that the ball solution has.
I have seen some older formula race cars or kit cars (not sure, and can't find a photo), where the gear lever has a small rod welded on with a spherical bearing at the end, which is then bolted to the chassis: Of course the gear lever will then pivot around a point somewhat off its axis, but I don't think that would be a big problem and all parts would be renewable. /Anders
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1982 Talbot Matra Murena 2.2 prep 142 (under restoration) 2017 BMW i3 "Charged Professional" 94Ah 2024 VW id.buzz Pro
Used to own: 2001 Renault Matra Grand Espace "The Race" V6 24v 1997 Renault Matra Espace 2.0 8V 1987 Renault Matra Espace J11 2.2
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njesper
Sr. Member
Posts: 128
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« Reply #29 on: October 09, 2009, 01:23:28 pm » |
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I am thinking about replacing the entire assembly with a cable activated one. My Xantia has cables instead of rods and it makes a huge difference. Think the leaver from a mr2 will fit, custom brackets shouldnt be to difficult to weld up.
Yo Krede, if you do that, please update this thread while you go along. I would love to get rid of that multi-jointed system, in exchange for wires. So sad to have a car, that looks cool, drives cool, but has a gearshift system, that makes it feel like a tractor from ww1. Best, Jesper
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