Wednesday's update, but a frustrating day

Nothing to update from today, but there is an update of sorts for Wednesday.

The aim for Wednesday was to sort out the Watt's link support in the boot. The first thing to do was to remove the spare wheel support. Thankfully, this is just twelve spot welds to drill out.

And that now gave room for me to start planning out how to actually fit the mount and what it should look like. I figured there were two main options: weld in a brace bar or sort a bolt in version. Weld in is stronger, but removes the ability to easily repair it in the future and it would be harder to fit. A bolt in version would be replaceable but possibly much harder to make. I went for bolt in in the end as it gave me the ability to mess it up and re-do it if need be.

The first thing to do was to cut a pair of plates to fit to both of the rear spring hangers. These would be the mounting points for the brace. Although the photo shows the bolts pointing down, the final version will have captive nuts on the plates to reduce the amount of metal sticking out into the wheel arch.

Then it was on with the cross bar and the mounting feet for the Watt's brackets that hang under the car. These needed to be a good close fit to the 1.5" brace tube, but also be wide enough to provide a wide mounting plate. This is what the final design looks like.

Four of these were then cut out in steel and drilled.

Using the existing mounting holes as a guide, these were then trial fitted to the shell before being tacked in place. The brace was then fully welded on the bench to ensure all four brackets were flat and straight.

Some of the mounting holes that I drilled before will need welding up and re-drilling now that I have a straight set of mounting points to aim for. But this won't take too long to do. The bit that did take quite a while, and even then I binned my last attempt, was to figure out a sensible way to join the cross brace to the spring hanger plate. What I was trying to do was to see if I could shape a short bit of the 1.5" tube to both meet the cross brace and still provide a good wide weld footprint on the plate.

After a good while of trying to get the two to meet I gave up. I just couldn't find a way make the shallow angle between the short tube and the plate work out. I think I will end up having to either use another short vertical section of tube to make the angle flat, which will look like the cups I have been using, or I will need to use two bits of maybe 1" tube to make a triangle between the plate, the end of the tube and the mounting feet. I have some 25mm x 3mm wall tube that would do well for this. I'm not sure which of the two options will be best. More thought will be required before I do either option.

New A frame completed and ponderings on what's next

Today was a day of mixed achievements. I got less done than I had hoped in the garage, but my son does now have a cardboard box plane that he's spent the day driving Mum insane with!

Today was all about finishing the A frame off and making sure there were no clearance problems. The first parts to make were the two long arms. Making the first arm was a bit fiddly, but it needed to be right as it was also the pattern for the second side. But both were shaped and then welded in before being re-fitted to the shell:





Using such long links on their own isn't the best idea. But that's partly why they're made of a high tensile grade of CDS, which is itself a high tensile grade of steel tube. And also why I need to put the last link in place to complete the A frame. This was made from 3/4" CDS, the same grade that the original A frame was made from. The main links are 1" tubing to help keep things straight. The cross tube was tacked in place on the car before removing the frame again. The frame can't be safely welded with the rod ends in place, as they have a self-lubricating liner, which will melt with the heat.



The frame was then put back on the shell to check for clearance issues. The cross tube was fairly close to the shell, and I suspected I'd need to make a small adjustment or two. It was two in the end as well, one pair of cuts to make the cross tube clear the shell and then I've marked the diff casing as that needs another small cut made to one fin.



With the shell cut back I decided to cut the new drum brake drive shafts down so I could bolt the hubs in place. This isn't needed yet, but I was running out of time so wanted something fairly quick to do before play time was over.



And with the hubs on, the back end is starting to look complete. And it very nearly is. There's just one bit left to make, and that's the link I need for the rear Watt's link mounts. Currently they are just bolted through the floor, which is obviously inadequate. So the plan is to make a cross bar that will link the rear chassis rails together and give a good strong mount for the Watt's links. I may also tie it into the roll cage if I go the whole hog with a 6 point cage. If not, I'll probably link it to the coil over towers. The plan in my head at the moment is to have one straight tube that goes across the centre of the 4 bolts with triangular plates that the go down and out to meet the bolts. A bit of 1.5" CDS should be more than up to the task. I will also probably add spreader plates to both ends of the tube to help both spread the load and make fitting them to the cured chassis rail easier. This will also mean removing the wheel mount, not that I would have used it anyway!

Today's progress

Since I'm dying of manflu, or possibly something even more deadly, I was only out in the garage this afternoon. But I did manage to make some progress beyond tidying up.

And that progress is on the new A frame for the rear suspension. As I'm changing the front mounts to be a much stiffer and more secure mount, I need to make a new longer A frame to match. The new mounts are based on the existing mounts, but cut down. The idea is to move the mounting brackets so they are in the middle of the bolts, rather than hanging off the shell on the bracket. These are the existing mounts:

And this is what they look like when cut down to the size I want:

The new brackets are based on a template taken from the existing mounts. All four were roughly cut but accurately drilled before being bolted together for shaping. This ensures all four are the same shape and have the mounting hole in the same place.

The brackets were then roughly assembled with the rod ends, threaded inserts and spacing washers, to allow a little extra adjustment should it be needed, before being tacked into place:

So with the brackets done for now, the threaded inserts needed welding into short sections of CDS. I decided to use these rather than rubber bushings as they're easier to make for a DIYer. Bushings require accurately sized tubing and are often press fit, and I don't have a press. And rod ends also allow a degree of adjustment that bushings just don't have. Plus, they're shiny.

These were then bolted back into the brackets and the whole lot put back on the shell.

With those done for now, the De-Dion tube mount needed remaking too. The Caterham A frame uses 1 1/4" tubing, but I didn't have any so mine are 1 1/2" instead. The only difference this made was that they needed a slight angle filing on one edge to clear the welds on the main tube.

Building up to another week off

Since I have some holiday stored up, I'm taking this week off work to make more progress on the Sprite.

In preparation of having the time off, I wanted to get the Mini uprights cleaned up and in primer. I need to get the outer suspension components together so that I can set the wheels correctly in relation to the shell before moving onto making a trial set of wishbones. The easiest way I know of cleaning up old rusty parts is using the power of science.

Since they were free, they used to look a little worse for wear, like this:




But if you put them in a bucket of water mixed with soda crystals and add a battery charger you can use the electricity to reduce the rust on the surface back to iron. This process takes about half a day for each part in my little plastic tub, but that's about all. It's cheap, a piece of piss to do and makes very little mess. It also leaves any machined surfaces perfectly intact and can remove a fair bit of grease too. This was my initial set up, and they were left in overnight:

 

Once taken out, they look better. Not great, but better. Ideally, you should surround each part with anodes (the scrap bits of steel), but I only had two usable bits to hand.

Since they weren't great, I decided to put them back in individually to get them looking better. Once they're given a quick wire brushing to remove any flakes of rust/iron, they look like this:



Not bad for 10-15 minutes work. OK, a blast cleaner would probably do just as well, if not better, but I don't have one of those where as I do have a battery charger and a bucket. This process can be applied to any iron/steel item and the only real limit is the size of the tub and the charger.


IMPORTANT 'Ealth and Safety bit: should you fancy having a go at home, please do. But DO NOT use stainless for the anodes. It makes a rather nasty chemical in the water called [url=http://en.wikipedia.org/wiki/Hexavalent_chromium]hexavalent chromium[/url]. It's mildly carcinogenic and can cause contact dermatitis. Make sure you put the negative wire on the thing to be de-rusted, as getting it wrong makes the part more rusty! Where possible ensure it's done in a ventilated space as the process gives off hydrogen gas in small volumes.


Once they were both clean and dried off, a few coats of engine primer were applied. I'm using that over other stuff as it's supposed to resist temps up to 500F, which should be way above what the uprights see. At some point I'll probably paint them black but they'll only get knocked in the next few weeks, so I don't see the point yet.

Record 74 painting

As part of tidying things up a bit of late, I decided it was probably about time that I actually got at least one of the Record 74 Autovices I have back in one piece.

So the one that was in bits has been treated to it's few two coats of Insignia Red enamel. I've no idea if this is the right colour, and chances are it's not, but it's a good match if maybe a bit bright.

The colour in real life is somewhere between the two photos, with it being nearer the red of the second photo. Once this coat has dried, they'll get a third and final coat before I contemplate putting them in the oven when my other half isn't looking to really harden the enamel! I might just have to leave in a box for a few weeks instead though.

Diff trimming

Not much going on in the Workshop at the moment, more getting set up ready for a week off soon so I can get stuck in without having to faff about too much. Not that it will stop me faffing about, just that I have less to faff about with.

So the diff fins were cut back roughly even, and then the diff re-fitted to ensure I had the right gap. At some point I will powerfile these round and even, but I couldn't be bothered the other day.

So there is now a 10mm gap between the fins and the diff at full droop, which is plenty. The next thing to do on the rear is to re-do the A frame. I've never been 100% happy with having the mounts hanging off the shell. I'm going to make a longer frame so the chassis mount will be directly under the spring hanger. This will make it much stiffer, and the new frame will have rod ends so I can adjust it more easily too. Being a relatively simple shape, it shouldn't take long to make the new one and the current mount can be cut down to save making new ones entirely from scratch.

The completed diff cage.

I thought it best to put the final stage in the diff cage up now the fabrication is complete.

The cage had the lower mounts cut off so I could make new thicker ones. Where the first ones were bent pieces of steel, the second versions have bee cut from 2mm thick 40mm box section. This makes them much easier to build as well as being stronger and thicker. Being wider, they will require washers inside them to prevent any crushing, but it also means that I can alter the positioning of the legs slightly too.

with everything bolted in place, the diff was levelled out as it was hanging tail down a touch. This did open a small gap between the legs and the mounts, but nothing wide enough to worry about with MIG welding. And so it was tacked in place on the shell before welding fully on the bench.

So the diff cage was finally completed. With the diff now in it's final place I could refit all the suspension to check for clearance. Before the diff was levelled there was a small gap. With it levelled and bolted in tight, there was no longer any gap.

So the final step in fitting the diff is to cut the cooling fins down a touch to create some space. I had expected to shave a little off the outer fins to clear the A frame link, but it looks like I'll be trimming them all back.