Chassis cut out now, ready for part manufacture

IMG_0894So, now I’ve managed to get the entire squabs and transmission tunnel cut out, ready to take the entire floorpan CF part.

It looks somewhat bare and scary, no? Overall, I’ve cut 22kg of steel and ally out of this arrangement, and some of it was especially difficult to get out. I’ve also cut out the harness mound points out as well – I’m going to reposition these as hard points in the composites when I know where I want the seat.

I’m going to go for post-fit hardpoints, in a sandwich arrangement. What I will do is drill the hole through the tub for the eyebolt hole, then use an allen key in a drill inserted in the hole to worry out the closed-cell foam core, and then I’ll fill this hole with an epoxy/glass bead filler. This will create a hard point to bold through.

In order to be belt and braces, I will also then put a bonded in stainless plate on the front, and the harness mounting plate, bonded on the back. This should give great anchorage. I will make a test panel as well to test this.

compound curves

Here is the join between the two bits of the tank – it’s taken quite a bit of time and bog to get this right, as well as using a flap disk on a drill to get the radius right. lots of polishing and filling as well. I managed to get some of the profiles right by taking a plastic bog-spreader and cutting a radiuses edge into it. I also found that a wooden tongue depressor also had a very useful profile for putting curves into things.

IMG_0060

More composite fuel tank updates

This post is really about some of the manufacturing detail I’m going into as I make the part. As I’m sure you know, the sensible route to getting a composite component is:

  1. Make the part you want out of any old stuff so you have to get the right mock-up shape. I’m using kingspan and covering it in glass. I also like kingspan because it sands really well with an orbital sander, and till take bog (body filler) nicely both as a glue and as something to put on the surface when building complicated shapes.
  2. Cover the part in glass so that it is rigid and all the foam is separated away because of course you can’t take a mould straight from foam – they will become one and we all know what happens when two become one.
  3. Where I can, I’m cladding the part in pre-made sheets of 450g chopped strand matt glass which I made on a pane of glass. The reasons are that firstly the sheet made from glass has a reasonable surface finish and secondly it’s a lot less faff to clag this on than wrap the whole thing in glass, set in resin and then flat and polish, flat and polish FOR EVERRRR until I have a sensible surface. Thirdly these sheets, being quite flat, mean I can trust the angles I have them in at so I can reduce the chances of mechanical lock.
  4. Where I can’t clag, I’m putting body filler in, which is great for filling the gaps, but must be recessed slightly back from the overall profile. The filler will then be coated in resin. This is because you can’t go body-filler straight to mould surface – when you pull the part from the mould you will leave the filler behind. So, for the want of a little deft work with an artist’s brush and some resin, I can avoid this.

As ever, this is easiest explained with pictures:

IMG_0064Here is the joint between two panels. Both panels have been cut and bogged down and while the bog is soft a bit of a push allows the bog to squeeze out into the gap, Add deft work with a lolly stick and the gap is scraped out.

You can also see a big gap between the panel and the part. This will be radiused back so I don’t have any right-angles into which I can’t get cloth.

IMG_0062Rivets are handy to stop the panel sliding down the part on the bog. whilst it’s claggy stuff, it still has a propensity to flow. I suppose this is another odd reason why kingspan is so useful – you can stick rivets into it.

 

 

IMG_0061Here is the bottom of the tank with the three panels attached. What you can’t easily see is the slight angle the tank tanks to follow the fury transmission tunnel, which is angled.

today Warren*, i are mostly making …

flat panels out of 3 layers of 450g CSM.

The plan is to try and get four panels made, ready for the next stage of the tub, which is the sitting in squab part either side of the transmission tunnel. It’s also a chance to practice my wet-lay technique.

 

photoI also think that if I am skinning both sides of a steel space-frame section with a diagonal in, then I don’t need the diagonal at all. Come to think of it, how brave should I go – make a full panel and dump the steel altogether? I could make a full panel and use a CF tube as a cross-brace if I wanted. If I made a panel it could be made from front-to-back uni-directional so I will be able to do it in two skins and a good core layer

Repeat to self –

I will not replace all the steel for a composite tub.

I will not replace all the steel for a composite tub

Now that I’m off to make the panels out of poly-resin I’m doing it outside, so hopefully I won’t poison the household.

Fury Front Anti-Roll Bar

I have my front ARB in place and I must say, I am exceedingly happy with it. I didn’t make it myself but comissioned Cornering Force to make it for me. It’s part of a matched pair (one for the rear as well) which was bespoke manufactured for my layout, corner weights and aspirations for the car. I can’t recommend these guys enough. Simon is a leader in the field and has his suspension on cars on pole in the BTCC.

So, to the pictures.

This is a view of the completed, powder coated rocker arm, showing the drop link going down to the blade, set in ‘fully priapic’ mode. There are a couply of other positive observations here – you can see how neatly it’s tucked under the rocker, as well as getting a nice view of the locking pin. The pin is spring loaded, and you just pull it out, turn the blade and it clicks home.

My car is only going to weight 650KG with me in it, so we only need one blade. Both sides are coupled of course so one blade does the work for both sides. The blade itself goes through 10 different metallurgical processes according to Simon so it will last the distance. It’s the single most expensive component in the arrangement.

Here’s a good view going into the adjustor, showing the nylon bearing block as well. As you may have noticed, I’ve decided to make all parts that bolt on to the chassis blue, and the chassis will be yellow again. There are small stops welded onto the ARB to secure it to the nylon bearings.

 

Here’s the final view, on the fixed link side. Nice and simple. What should also be evident (and is also clear in the top picture) is the line of sight between the chassis force node (top rail where the vertical meets it) and the far corner node where the suspension mounts. If you look at this and the top picture, you will see where the next set of cross-bracing is due to go in. I will make this cross bracing demountable otherwise it won’t be possible to get the right angle of pitch when extracting the engine.

how I made my engine mounts – very happy with them

How I made my engine mounts putting a duratec in my fury rebuild

So, as part of rebuilding my fury and shoving a duratec engine in, I decided to make some new engine mounts. I wanted to reduce weight and improve the packaging as well – the old mounts used up a lot of space that could otherwise be spent moving mass down – I have swirl pots and fuel pumps to put somewhere after all.

Firstly, I went to Fast Dan (DanST Engineering) and ordered some engine mount plates. They’re a great fit. I think the price is good value and there are times when buy is far better than build.

Secondly, I decided on the design, and went for something inspired by SBDev and which gave me quite a compact result and rather contradicted the original design that was somewhat agricultural (see the picture on the right). The original design was from my previous pinto installation.

So, here is the assembled list of bits. Rather than go for a huge rubber mount (which of course would be good for absorbing vibrations) I’ve taken a gamble on using (reusing) the bushes I’ve taken out of the suspension. I’ve fabricated everything from 32mm dia 3mm thickness CDS. The sleeve inner diameter didn’t match the bush outer diameter, so I bobbed over to a friends and put it into the lathe. It was then machined out to take the bush with a reasonable amount of slack, knowing the sleeve will clench up a little when welded.

The mounting plates needed to be notched in order to accommodate the way the plates were offset when mounted on to the chassis rail. Note that each plate is a different size to account for the angle of the rails; I wanted to feed the load into the chassis at 90 degrees, rather than an angle. An angle would mean putting some bending load to the leg from the plate to the chassis (not ideal). In order to get the hole in the correct place for the plate, I hand-fitted the sleeve and plates to the chassis, and clamped it with a welding clamp (you need a third hand for this, thank you Zaphod). Then I used a CD marker pen to draw around the sleeve, added cross-hairs after dismantling and punched a hole.

These plates are 3mm stainless (left over scrap), so you can’t just go riving at them with a 1/2 inch drill bit (the bushes are the standard, mandatory, obligatory, inexplicable 1/2″ inner diameter). I started out with a 3mm hole, and went up in increments of 2.5 or 3mm, depending on which bits I had to hand. I also found that the cobalt set of drill bits bought from tool-station started to show their value. A cheaper set of bits just screamed and blunted making virtually no impact on the hole, yet the cobalt ones cut through nicely. I also used a spray cutting-oil (and lots of it) to help things along.

The thing you have to remember is that drill bits don’t cut round holes, and the larger the bit, the more obvious this becomes. Once I’ve got the hole out to 12mm, I then ream it out to 1/2 inch. I bought a tapered reamer from ebay for not a lot of money and it’s done me proud. It reams stainless out as well, but again, it wont go out more than 0.75mm. You can see on the right here how the hole isn’t perfect before reaming.

Next, I needed to machine the down-leg to fit the sleeve. The sleeve was cut from the same tube I’m making the leg from, so that was at least reasonably simple to cut a matching fish-mouth. I used this software, printed it out, stuck it to the tube and got busy. I cut the majority of the metal away with a 0.8mm slitting disk, and then tidied up and ground out to the the marks using a tungsten burring tool on an air-die grinder. You can see the results yourself on the right.

There are other things to note in setup before finally welding it together. The main one is to try and have the engine level in the chassis. It helps to keep coolant and oil levels as horizontal as possible. I used a spirit level on the back of the car to be sure the chassis was level (it was) and then put the same level on the flat gearbox top to be sure i had the engine in the right place: one can’t really take a measurement off the top of the duratec: it’s all curvy.

I found out that chocking the engine in place was tricky – the chocks were difficult to place and kept popping out. Interestingly, a run of duck-tape from the chassis rails to the top of the engine was a great way of keeping it in place (Thanks Darren – very smart move). Duck Tape is like the force – it has a light side and a dark side and it holds the universe together.

This is what the mount looks like from the engine down to the bush:



and this is what the whole lot looks like when nailed together to try the fit. The offset between one bracket and the other is more noticeable on this side.



Finally, this is what the almost completed installation looks like. There are a couple of points to note – I’ve put a reasonable seam in to hold the bracket facing the camera (and the one you can’t see the seam on) but I won’t be able to complete the seams until I get the engine back out. This was part of the plan – the engine is just a dry-build at the moment to be sure I have everything in the right place.

I still have one job left, which is to put a bracing plate in at 90 degrees to the bracket to tie the front-to-back loads to the chassis. I don’t think the loads will be all that significant, but they may eventually fatigue the joint. I only need one plate because the bush will transfer the load from the other bracket to the bracket with the cross-brace. It’s only going to be a few grams of steel but it’s worth getting right. Even if I’m being paranoid I’m only wasting a few grams.

Speaking of which, each mount is 500g lighter than the previous, so I’m a kilo up on the deal as well.

Add strength for little weight – seam welding

So, I remember from years ago, a friend of mine told me how he prepares RS2000 shells – after buying a second-hand one in good shape, it would be stripped back to the metal and seam welded rather than spot welded.

Mine isn’t seam welded where some of the strong panels join the spaceframe, but stitch welded (i.e. one cm of mig welding for every 5 or 6 cm of space). It’s quick, stronger than spot welding, but let’s face it – it’s an economy solution.

So, now I want you to queue the Ghostbusters theme in your head and hear me sing “welding makes me feel good”. As a result, I thought I’d quickly try a couple of quick seams in an easy to weld area to see if it’s worth the hassle. Quick answer is yes.

There are a couple of issues with the quick approach I’ve taken to see if it’s sensible.

  1. Firstly, grinding the existing the existing powder-coat back isn’t too tough a job (circular belt on the dremmel) but you need to go back quite a way, which I didn’t. The heat of the weld made the powder-coat peel back. I’m going to get a blow-torch and see if this will get more of the powder-coat off. This leads me to my next point:
  2. The powder-coat gives off fumes when burning away. I’ve had a sniff of this and it’s not pleasant. I will need to do the burning off with the garage door open, ideally with a breeze. Once I’ve burnt off the bits I want off, I’ll then weld it. One big burning. Maybe with a fan.
  3. There is a little inevitable powder-coat down between the gap of the panel and cross-member it’s stitch-welded to. This will cause a little pollution of the weld. I have a really nasty pointy grinding tool for the dremmel which gets most of the powder coat out. It’s evil, and I’d love to turn it on a dentist some time.

So, here’s the welds – they look good and really nicely round the corner off. The holes aren’t blow-throughs but screw-holes from whatever was mounted on there.

And here are some photos:

  

Here you can see the first weld, and the second shows stitch between the seams.

More additions to the weight loss programme

So, all the lovely things arrived from RWD Motorsport today to attach the engine to the gearbox. I don’t have time to fit them yet (need to get the old engine out), but I did at least bother to weigh one crucial component – the flywheel. I’ve logged the new weight here in the weight loss programme page, but here is the headline figure: 12.7 down to 3.2.

That’s a scary loss of weight, and hopefully it doesn’t make the car undrivable. It should also be exciting with the AP Racing clutch that’s going in. So far, only my friends Jon, Sasha and I have managed to drive it without stalling. This new transmission installation will take it much closer to race-car in it’s feel; it should now at least give them a challenge.

And for your visual delectation, here it is in the flesh, next to the monster duratec item, or as my friends would say: Pics, or it didn’t happen.

i am the moon

as thin as a dead model

if I had a degree in divinity (BD), would that give me a degree in having an imaginary friend?

Corner Weights

As part of the work necessary to design and fabricate my ant-roll bars (which I think will be a thing of beauty in twisted metal form), Simon and Mike from Cornering Force came around to take the corner weights. They had to do this on my pair of scissor lifts which shows they are game for anything.

Following is the breakdown of the corner weights, including the driver. It is a wet weighting, and the weights are reasonably well placed with a little bias to the right. This isn’t going to be very easy to change, but most UK circuits have a predominately right-handed bias, so I’ll cling to that as a benefit.

It’s going to be very interesting to see how the weights change once I’ve finished the build.

Proposed weight loss

So, I’ve been thinking of all the ways of getting weight out of the build, bearing in mind I am going down to a full-chassis rebuild. I also mined the excellent locostbuilders.co.uk site with this thread, which had some excellent advice.

What Approximate Weight Description
Duratec Swap 45 The pinto is heavy
Lighter Seats 5 (x2) My padded seats are heavy, but changing them may have to wait for funds/td>
lighter shocks 2 needs new shocks anyway