| Home  Blogs Help Search Login Register  
« previous next »
Pages: 1 [2] 3 4 Print
Author Topic: Modifying gear shift  (Read 26162 times)
krede
YaBB God
*****
Posts: 1166



« Reply #15 on: October 03, 2009, 03:52:24 pm »

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.
Logged
Anders Dinsen
Administrator
YaBB God
*****
Posts: 2823



WWW
« Reply #16 on: October 03, 2009, 05:33:02 pm »

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
Logged

'82 Murena 2.2 prep 142
'01 Grand Espace 24v
'08 Smart Fortwo 0,8 cdi
Jon Weywadt
YaBB God
*****
Posts: 962



« Reply #17 on: October 03, 2009, 05:37:47 pm »

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  Wink )

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.html

By 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.
Logged

Matranaut par excellence Cool
Titus
Sr. Member
****
Posts: 145



« Reply #18 on: October 03, 2009, 08:06:54 pm »

Hi Graham,

The car you refer to with the closer pivot is Richards 1.6. If you are going to the Wobbly Wheel meeting tomorow he may be there, although he has had the car for sale for sometime now. If so I will take a photo showing the mod. As I recall it was a simple and effective solution. That being said your slick change seemed all but perfect to me whilst driving your car down the strip at Santa Pod!

http://www.youtube.com/watch?v=9of98pahiUs
Logged

1.6 Murena
GP
Guest
« Reply #19 on: October 04, 2009, 11:18:29 am »

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
« Last Edit: October 04, 2009, 11:21:34 am by GP » Logged
Anders Dinsen
Administrator
YaBB God
*****
Posts: 2823



WWW
« Reply #20 on: October 04, 2009, 02:30:43 pm »

I have noticed that the rod is rather soft and can twist quite a lot, and that's probably one good reason for the sloppy gearchange the Murena is known for, but your modification must also put the rear joint under a good deal of pressure?

Anyway... this has made me think and there's a way to redesign the linkage using a universal joint in the middle. The rear link is preserved, your "sliding retainer" is too, and the rubber ball and top hat bush in the bottom of the gearstick. But the long rod is broken in two with a joint in the middle:



/Anders
Logged

'82 Murena 2.2 prep 142
'01 Grand Espace 24v
'08 Smart Fortwo 0,8 cdi
GP
Guest
« Reply #21 on: October 04, 2009, 03:54:24 pm »

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?

-------------------------------------------------------------------------------------------------

All the best,

Graham

Logged
Anders Dinsen
Administrator
YaBB God
*****
Posts: 2823



WWW
« Reply #22 on: October 04, 2009, 04:25:23 pm »

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 Wink I have been thinking about something like this for years, never able to find a solution Roll Eyes - 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.asp

Note, 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.

Quote
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

Logged

'82 Murena 2.2 prep 142
'01 Grand Espace 24v
'08 Smart Fortwo 0,8 cdi
GP
Guest
« Reply #23 on: October 04, 2009, 07:42:31 pm »

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.  Wink

 (She has been there before, usually via Maidstone Machine Mart!)

All the best,

Graham
Logged
Bart_Maztra
Sr. Member
****
Posts: 207



« Reply #24 on: October 04, 2009, 07:59:00 pm »

Hmmm, trying to reduce the sloppy gear change by introducing yet another link???

The original isn't bad if all the worn components are changed.  I've driven low mileage 2.2's which have really slick changes but it's quite easy to get older cars up to near that quality.

While the original sockets had nylon liners we find that  solid steel ones are better and you can change the gearbox relay bushes from nylon to brass.

The worst part of the system is the top hat washer under the gearlever. but it's a cheap item and easy to change to get rid of lateral slop.

This is the way to go.
And fix the play of the ball joint of the gear lever itself.....


Logged

Jon Weywadt
YaBB God
*****
Posts: 962



« Reply #25 on: October 04, 2009, 09:01:37 pm »


This is the way to go.
And fix the play of the ball joint of the gear lever itself.....

I am very interested in what you guys work out. I have had the gear shifter out a few times trying various things to reduce the play in the ball.
No success yet, but my next attempt will be either to cast some additional plastic onto the existing ball and then turn it on a lathe to the right size.
Alternatively I will turn a whole new lower shifter part that includes a ball in metal.
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.
Logged

Matranaut par excellence Cool
Anders Dinsen
Administrator
YaBB God
*****
Posts: 2823



WWW
« Reply #26 on: October 04, 2009, 09:15:27 pm »

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.  Wink

 (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
Logged

'82 Murena 2.2 prep 142
'01 Grand Espace 24v
'08 Smart Fortwo 0,8 cdi
Titus
Sr. Member
****
Posts: 145



« Reply #27 on: October 05, 2009, 06:55:32 pm »

Here is Richards mod.
Logged

1.6 Murena
Anders Dinsen
Administrator
YaBB God
*****
Posts: 2823



WWW
« Reply #28 on: October 08, 2009, 03:30:02 pm »

Here is Richards mod.

That looks like a very simple modification. I didn't think about the fact that the arm has a slightly bent shape so the control rod can still reach to the other hole... great idea!

/Anders
Logged

'82 Murena 2.2 prep 142
'01 Grand Espace 24v
'08 Smart Fortwo 0,8 cdi
njesper
Sr. Member
****
Posts: 125



« Reply #29 on: October 09, 2009, 01:23:28 pm »

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.  Wink

Best,
Jesper
Logged
Pages: 1 [2] 3 4 Print 
« previous next »
Jump to: