So its been about 2 years since I started this build thread which means its about... what, 6 years since I bought the car?
As we all know this thread was started with the intention of getting the car to the Gathering 2018. As much as I'd like to say the car was now finished.. it certainly is not. If I'm honest the car hasn't been touched other than to move it to my house back in 2019.
Following the Retro Rides Weekender beer and BBQ chat and seeing the show back up and running... Plus the Gathering going ahead this year... I have an urge to get back into this project. I'm being more realistic with my expectations and time scales this time around however. The smash-athon that happened 2 years ago was a great achievement but was too ambitious.
Lets talk Propshafts...
Having run the car on axle stands and taking it for a very short drive the first job was to stop the frame from flexing. The flex and shimmy effect was being cause by a slight misalignment within my propshaft assembly. This isn't a massive shock considering. The main flaw was with my prop design... the prop only had one CV joint. As much as I hoped this would be enough to take out the tolerance in axial alignment, offsets and distances etc it does not free up ALL the degrees of freedom. I needed a second CV joint or a rubber donut or some such to achieve this..
Due to this being a fundamental requirement for driving the car more than 1 mile before something fatigues and cracks it was my first priority. If I found I was unable to design a prop that was short enough this could knock onto moving the diff forwards which would mean a frame redesign and could knock onto driveshafts etc.
So now I have the challenge of designing a prop with 2 CV joints within this space.... Its blumin' tiny.. (and now rusty)
My research lead me to find that most 100mm CV's use the same bolt spacing etc its just the number and size of splines that alter. I had a look for the cheapest 100mm CV I can. Looking at used driveshafts etc, something that comes with the matching splined shaft. Believe it or not I found a brand new driveshaft at euro car parts for £27.80... I think it was for a Porsche 944....
First job was to check my research was correct and test the fitment into the BMW cup.
It didn't quite fit... new CV was slightly too large.
The BMW cup spigot was 99.5mm and not 100mm. So into the lathe to take it down to size.
BMW cup uses M10 bolts so I had to drill out the new CV and now it fits!
The next challenge was to make a 100mm CV bolt up to my sprocket adaptor.
As the adaptor and CV were both 100mm OD I simply turned a small spigot locator into the front face of the adaptor and turned down the outer of the CV joint to suit. These two parts now locate together concentrically.
I fully welding the sprocket into the adaptor. Now that we are going to a 6 bolt pattern it was a sure thing I will be drilling into a set of sprocket teeth. This was drill braking territory if I don't remove the voids and edges and the heating helped to slightly remove the hardness of the sprocket.
Pilot drilled.
With the adaptor fully drilled and tapped to M8 I can assemble both parts onto the car and start working out shaft lengths... its gonna be shawoorrt...
The bandsaw wouldn't touch the hardened shafts so cut them off with a grinder. This whole process will be very similar to how the driveshafts were made. Drill and ream a hole on one part and then turn down a dowel pin to suit on the other. Press them together and weld it up.
I made a split sleeve to grip onto the splines.
Centre drill, drill and ream (with a mill bit as this is all I have...)
Two parts that don't quite fit together, yet... (which is good)
Some like it hot... others like it cold.
Pressed together and the length is spot on.
Before I welded it I thought I best do a test fit and it all seems really nice.
Hot glue gun time.
Gave it the full 250amps I have.
Clean Up.. and it was running pretty straight on the lathe after welding which is good to see.
Looking pretty damn good I think.
I made a boot using just one ring off a boot and crimped it back into the other back plate. Took ages and was a pain to make.
I think that will do nicely. I need to re think the bolt choices as tool access is very restricted (obvs not using 8.8 grade hex bolts... these are just for mocking up.)
I ran the car up and the shafts were willing to turn slowly just on the clutch drag in neutral. That's got to be a good sign of how easy it is to turn. No more tight bits and loose bits causing stress in the frame. Disaster averted, I think.
