#21
Well as I just alluded to in my previous post I started to design my own Gearshift.. I'm going to document the process below:
The first step was to bolt in the seat and get the steering wheel in the correct place.
I then mocked up, using an old mk1 mini gearstick and some random items from around the garage, a temporary gear stick and switch panel which I could move around the car until I liked the position.
I wanted to feel comfortable whilst changing gear and have a good line of sight to the switch panel etc. I decided to have the switch panel mounted to the gear stick mount as I am going with the MK1 dash for weight saving and asthetics, and also it would be ideal as then I could get the switches within reaching distance, while reducing the number of components (not having an additional switch panel mounted to cage)
The final position was set.
The gear stick sits approx 200mm rearward from the original position and alot higher!.. higher than the pure kit too!.. Its in line with the centre of the steering wheel both vertically and longitudinally. (such a comfortable position, also means I don't have to reach from from the steering wheel to change gear)
Switch panel can be reached comfortably also
With the position set I took a million measurements of where the top of the gear knob and switch panel were located so I could start to design the system on CAD.
Initially I measured the travel/throw of the existing gear stick in my mates trophy.
Laterally it moves +/-40mm (80mm total) and fore/aft +/-70mm (140 total) (meaured at the centre at the top)
I then modeled the rod to calculate the lever ratio which in turn gave me the travel at the lower end.
I then translated these new lower end set of points to the desired +200mm position.
I then decided on the reduced travel/throw i wanted at the top of the new rod, which was (+/-25mm lateral and +/-45mm fore/aft)
This then determined the new bearing centre based on the new calculated lever ratio.
Few pics below of the process:
I then ordered some bits from Pure Motorsport as they were cheap and i didn't want to have to make them.
-Gear Knob
-Reverse Sleeve Spring
-Bearing Lock Nut
I then bought a new PTFE lined Minebea Bearing!.. Defo worth the cost as there is no stiction or play in it!
All these parts were modelled up and added to the assembly.
The pictures below show the design nearing completion and the blue points show the positions of the lever for each gear.
Also you can see the reverse sleeve modelled in all positions, required to calculate the diameter of the sleeve, and position of the side plate to ensure reverse is only selected when pulling the sleeve up etc.
I then set about doing all the drawings for the parts and getting them made. I was able to turn up most of the components myself on the lathe, however the bearing housing and reverse sleeve bosses were machined on a good friends CNC lathe which he did for free for me.
All the steel tubes have had the profiles flat patterned and printed out, then wrapped around the tubes, so much easier than guessing.
The steel frame is made from CDS steel tube and the rod is made from Stainless 304
Just the simple task of fitting it all together now 😅
First job, press the reverse sleeve bosses onto the end of the pre cut steel tube, turned to length
Then fit the nylon bushes into both ends. These are a nice sliding fit over the rod and should prevent any rattling against the bearing assembly.
The Reverse spring was then installed over the rod
And finally the Gear knob was screwed onto the end. (with a nice aluminium anodised bolt, OCD again)
Next I slid the stainless threaded boss I had made through the bearing and the locking nut was then tightened on
I then placed the rod through the boss and located the bearing in the housing and retained it with a Spirolox (type of circlip, but better)
I then clamped the rod in the vice to test the assembly... Looking pretty similar to the CAD!, always a good sign.
A quick vid of the reverse sleeve action.. Nice and positive.
Next step was to make the frame..
I started by clamping the Bosses onto the tunnel (You may remember these from previous posts) . I also previously welded up the handbrake cut out on the tunnel
I then used a steel tube turned to an exact length and angled to the correect angle to position the bearing and bearing housing in the desired location.
With the housing in position I tacked on the rear brace tubes
Then the front brace tubes
I then welded up the switch panel square on the bench before jigging and tacking on the central support
Then I tacked on the final 2 switch panel supports and the frame triangulation tubes
With the frame all tacked up and checked, I took it to the bench to be final welded
The next job was to bend the stainless lever at the correct position to the correct angle.
A bit of clamping, tweeking and bending and it was all done!
The bearing threaded boss was then pushed on and set to the correct distance from the end of the lever rod.
Then it was welded in position
The bearing was then bedded in on the pillar drill... If you use PTFE lined bearings there is actually a proper beading in procedure where you heat up the PTFE by rotating the inner and causing friction, this then 'melts' the PTFE liner to the exact profile of the inner. This reduces all friction in the joint whilst not inducing play in the joint. I have done this many times; it is a tricky procedure, there is a risk of over heating the liners and damaging the bearing. This procedure is direct from the bearing manufacturer.
I then put it all back together on the bench before installing it back in the car to start working on the linkage to the gearbox.
I made a quick aluminium switch panel plate which i will be using to mock up the switch positions before I make a carbon version.
Few pics of it in the car!.
I then cut out the tunnel for the new rod location. This will be all welded up when the linkage is finalised.
I installed the engine/gearbox and subframe back into the car to enable mocking up the gear linkage and to ensure the gear shift system could locate all the gears efficiently.
I also fitted the rubber gaiter and connected the linkage up (I will write another post on the linkage, it was the last thing I did last week so don't have any pictures yet.)
I then welded on the 1st/2nd/Reverse side plate. I also welded on an additional plate for 5th gear. I wanted to ensure that there was a stop so as to not put excessive load on the linkages by over extending the lever rod. It has a really positive feel now!
the gaiter was fitted to aid in the fabrication of the tunnel closing panel etc.
Here's a little video showing it all working and selecting the gears. You can also see how little play the system has at the end too. (excuse the heavy breathing haha)
Like i said before I will do another post showing the linkage, if people want.
I hope you enjoyed reading it. I am really happy with the outcome of it.. I just need to finish off welding some tabs for the brake bias to be mounted and it can be sent off for powdercoating and plating.
Another job ticked off.. Just the steering wheel /column mount to sort out next!