Gear Linkage - What's the way forward with this?

[Dilkris]

OK - I know you have all been here at some stage so I see no reason to re-invent the wheel. 
Mechanically, I finally have only 2 areas remaining on the rebuild, one being refurbishment of the rear hubs, this is in progress and is  being covered under the thread "Rear suspension Housings - Worn" and the second area, being the gear linkage.

Please refer photo's - PO's have clearly had trouble with scroll pins, have re-drilled, welded and produced this masterpiece.  It is reasonable to assume that the "surgery" was performed in situ.

I have some ideas - but does anyone have one that works??

"No" it is not my intention to buy a new assembly..... 

Surprisingly, whilst the "rose joint" shows signs of wear along with the bush within the bracket to which it is attached, there is minimal wear in the UJ joints. 

So I am clear, the UJ Joint is captured at either end by left and right hand threads correct? This adjustment being required to enable the effective total length of the linkage to be adjusted so as to place the gear lever in the correct front/rear position. Yes?     

[SilverBeast]

Also I believe the relative axial positions of the front bar (from the gear lever) and the rear bar (to the gearbox) also set the left/right position of the gear lever too!

I have not yet had the joy of having to adjust mine, but I'm sure it's only a matter of time...

[TurboFource]

Makes me think....cable shifter 

[Dilkris]

Yes - it just makes me think.....

There must be a better way of engineering this adjustment - it seems we are chasing longitudinal and axial adjustment in the system as highlighted by SilverBeast - I'm thinking why can't the adjustment "arrangement" be on the first gear linkage tube (about 12" back from the gear lever) accessed through the oval cut out in the backbone of the chassis? 

[SilverBeast]

To be fair it's probably easier to adjust it where it is, as trying to drill and fit roll pins via the access hole would be a nightmare, and you'd probably only be able to fit them straight down. Immobilising/supporting the tubes while drilling and fitting the roll pins would be "challenging".  You would also lose the opportunity to "add lightness" by re-drilling at other angles at a later date 

I'm not saying it's ideal by any stretch of the imagination.

I'm about to order a rolling body/chassis dolly so I can lift mine a bit and move it around.  I can then diagnose and treat it's "senior problems" - it seems to dribble all it's fluids (apart from the screenwash, but then I haven't tried to use that!).  Latest is dripping petrol from the bottom of one of the Dellortos, so I guess it's time to address all the things I've put off since I got it nearly two years ago.....

[EuropaTC]

If the UJ is good and you just need to replace the rose joint then it's not too bad. The rose joint has Loctite to keep it in place, there's a fairly detailed section in the manual (Transmission section) that goes through the procedure with exact measurements to set it all up.

As you've got it on the bench, unless the UJ is absolutely perfect I would replace both middle/rear UJs as well as the rose joint & support bush. It's a long linkage and the slightest bit of wear seems to be magnified when you're changing gears. Getting everything back and then finding out the gearchange is vague isn't something you'll need !

I'm about to order a rolling body/chassis dolly so I can lift mine a bit and move it around.  I can then diagnose and treat it's "senior problems" - it seems to dribble all it's fluids (apart from the screenwash, but then I haven't tried to use that!).  Latest is dripping petrol from the bottom of one of the Dellortos, so I guess it's time to address all the things I've put off since I got it nearly two years ago.....

   it is approaching OAP age y'know.....

Seriously the petrol leak is a bad one considering we've got a distributor sparking away underneath.  If it's the same as I had, the diaphragm in the base of the carburettor (accelerator pump) will have split. An amazingly bad design compared to the acceleration circuit in webers, I'm surprised it's not a more prominent service item.

[TC2000]

Hi All,

I also had to rebuild the gear linkage.
In my opinion, the system with roll pins is inadequate: hard to adjust and after several assemblies the rods are nibbled and good for trash. 
The front linkage rod needs to be shortened to allow an adjustment with a jam nut and enough space to adjust the longitudinal location of the 1/2" heim rod end.

Comment on the attached picture:
- at the top : the linkage as taken out from the car; the thread to the front rod has been sectioned by the pins; the rose joint needs to be changed
- at the bottom, parts used to rebuild, from left to right (all in 1/2"UNF): threaded rod RH thread, RH threaded insert, RH nut, RH male rod end, universal joint (UJ) (from RS components, inner diameter 12mm), LH male rod end (cannibalized to get the LH thread), LH thread insert

The front link is shortened and a new RH thread insert is welded (at 10 degree angle); an 8mm hole is drilled through (perp to axis) 10cm from the end to allow to block while tightening the jam nut . The UJ is threaded 1/2 UNC RH on one side. The LH rod end is cut to get the LH thread end and one end is turned to 12mm to fit in the UJ; UJ ends are drilled and taped to put M6 allen stopscrews. I did not finally change the LH insert on rear link, Nuts have been modified (lathe) to allow large angle of the RH male rod end.


On the picture showing the assembly: rubber protection around the rose joint (also available from RS components); 1/2"rod end is located between 2 modified jam nuts; jam nuts of both links (RH and LH); strong loctite on both sides of the rose joint. To adjust: loctite on both RH and LH threads, adjust length, insert a screwdriver in the 8 mm hole and tighten jam nuts, test, readjust, final tightening of all jam nuts.One allen stopscrew is visible on rear link insert. The pivot assembly is using the original bracket, 2 M6 male rod end and a fabricated vertical plate where the 1/2"rod end is located (need to shorten that rod end).

Total cost around 80€ (from mcgillmotorsport.com and RS components); need a lathe and welding.

Hope it helps

[MRN I J]

McGill Motorsports are a Sottish company

[Dilkris]

I also had to rebuild the gear linkage.
Hope it helps

TC2000 - Many thanks for posting this - this is a big help as I was thinking along similar lines. Are the M6 grub screws holding?

I may come back with further questions as I progress this part of the refurb.  Chris   

[TC2000]

TC2000 - Many thanks for posting this - this is a big help as I was thinking along similar lines. Are the M6 grub screws holding?

I may come back with further questions as I progress this part of the refurb.  Chris

The M6 screws are used for temporary adjustment as the link centers of gravity are offset (since I am alone and they tend to twist during assembly, and I have only 2 hands) .
For me, M6 screws are as good as roll pins to hold torque, without big damage to the thread core.
- For the links, I have the M6 screws, loctite on thread plus jam nuts with loctite. That should do the job to hold the torque (Hulk cannot drive Europe anyway  )
- For the UJ: on RH side=M6 screw plus 1/2" thread with loctite; on LH side= M6 screw + tight fit 12mm and loctite (I do not have a LH tap, could consider a tack weld)

This whole setup allows to modify the adjustment as you wish without degrading the components; on contrary, the roll pins system eats up the threaded ends of the UJ, every time you modify the adjustment.
The good side of the roll pins is the reproducibility if nothing around is altered.

Enjoy the ride,
Bertrand

[Dilkris]

  entirely.

Think I'm going the exact same way as you except I managed to track down an overhaul kit for the original UJ and I've just bought a 1/2" UNF LH tap... !! It's going to take a bit of work, (the UJ will have to be cut up and re-fabricated as the RH and LH thread sections are pretty much destroyed)...

It amazes me that someone could actually dream up the original design of this linkage - not withstanding it's short comings, it really is quite brilliant. 

[Dilkris]

Hi All,
.......the front link is shortened and a new RH thread insert is welded (at 10 degree angle)......

Hi TC2000 - the above is a small part of your earlier thread - I measured this at 15 degrees, but I have to ask the question, from your first hand experience, "How critical is it - will anything between 10 and 15 be ok...?? 

[pboedker]

Very nice solution, TC2000 

When i worked on the same task 20 years ago, I snapped the front rods, maybe because they were locktite'd as well as having been drilled thin. So I ended up with having to use the lock nut method also, although I could otherwise re-use the old parts.

But what I found was that the lock nut had to be ground thinner as not to be in the way of the rose joint movement, when doing the shifting movements fore and aft. I even had to adjust it very precisely to be perpendicular to the length axis when in neutral, to get enough free movement when selecting the gears. I hope your second photo is after having already selected a gear, otherwise (at least on my car) there wouldn't be enough movement left to select it. Some times a rose joint has domed washers around it, but in this situation I think there is only room for a selfmade 'domed nut' if necessary.

So just a heads up - from my experience - that this part of the linkage might need a very precise adjustment at neutral, and the rose joint needs to be able to turn sufficiently in the fore and aft direction. Or else...

[Dilkris]

pboedker - I understand the impact of the half nut (lock nut) to the left of the rose joint restricting movement.

My situation is such that I am intending to cut and replace the left and right hand threaded sections of the UJ joint (as the original threaded sections have been excessively drilled - one even snapped after spending a couple of hours carefully grinding away the weld applied by PO's - see original photo on this thread.). I am also cutting and replacing the threaded sections (bosses) on the selector tubes for which these screw into as equally they have been excessively drilled .

So - in doing so - note I haven't done it yet - I'm still collecting the bits - (32mm Bright bar stock, 1/2" AF LH Tap, 1/2" AF LH & RH Bolt plus half nuts) - could I not effectively shorten the overall length of the first selector tube and replace this "shortening" with a longer threaded section, (this is fortunately the RH threaded side), thereby arriving back at the original overall length BUT in doing so making more room for the rose joint movement as it will be moved away from the half nut.

Does this make sense? If not I'll post some photo's when I have cut up the assembly into the component parts.

Just out of interest - once the assembly is adjusted - how often does it have to be re-adjusted? You state you did this some 20 years ago - do you still have the same car ?

           

[TC2000]

could I not effectively shorten the overall length of the first selector tube and replace this "shortening" with a longer threaded section, (this is fortunately the RH threaded side), thereby arriving back at the original overall length BUT in doing so making more room for the rose joint movement as it will be moved away from the half nut.
   
   

It is exactly what I did. Maybe my text was not clear: shorten the first selector tube to allow enough space for :
1/  the jam nut
2/ 2 nuts each side of the rod end; and these nuts need to be turned to allow larger angular range of the rod end.

And by the way buy a large outer diameter threaded RH boss so you can weld it at an angle (tube is 1")