Derek's 308 engine rebuild

Just a heads up to anyone pressing in new A-arm bushes-- check that the A-arm doesn't crack as you press in the new bush. Luckily my friend Henry, who is helping put the car back together, spotted this one when he was going to tack weld it. The crack formed from a previous weld point that I had ground off. I should have filed any grooves at the edges to be rounder and reduce stress concentrations.
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I got the brake brackets back-- they're made in 7075 so almost as strong as a medium carbon steel but very light. For anyone who tinkers with CAD and doesn't have expensive software, I found a free online FEA provider which was a nice find (simscale)-- I usually get someone else to do it who has the software. My "off the top of my head" cutouts actually stood up pretty well to the simulations. I just need to borrow a drill press to drill the new mounting holes in the Wilwoods (between the standard holes and the body) as I gave mine away when I left Canada. I’ll post some pictures when I get it all together. I tried the Boxter discs and Wilwood calipers inside the 14” wheels and it was quite close to fitting. When I moved the wheel 18mm outwards from the original offset it would clear or be very close. A few mm can be cut off the outer edge of the disc. I’ll see if I can find a similar disk with a deeper hat for the 14” wheels.




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I finally had time to pick up a drill press and get the brake kit together. There were a few things I had to file and grind with a Dremel but it all fits together well. The countersunk screws were 0.5mm proud of the bracket so spun them in the drill press and ground them down a little. The outside raised boss on the mount holes had to be filed flat to give a flat surface for the adapter plate. I will Dremel off part of the inside boss to match the washers. The disks touched on the inside so I Dremelled off a couple of contact points on the inside of the caliper bridge.

If I was only building these brakes to use inside 16-17" wheels I would have used a radial mount Wilwood caliper but went with this setup as I can remove the plate and switch to the original disk and 14" wheels. If you want to go this route send me a pm as I have 4 extra pairs of brackets and countersunk screws (finally found them at Misumi so bought a packet and ground the all down flush for the brackets.)
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I had a question about the bracket price and the lug stresses after drilling. The brackets are £100 for a pair incl. four of the 12.9 steel countersunk screws. If you want help sourcing the Porsche disks and Wilwood calipers I can help but best prices for both are mentioned above.

The drilled lugs are still plenty strong. I ran simulations and the highest stress is on the leading hole when the new holes are used (with the bigger disks.) Even when I put all of the force onto the thin wall of that one hole it is still well below the yield strength of forged aluminium. In reality the force is distributed to the contact surfaces on both sides of both of the lugs so the factor of safety is high. Here are a couple of photos from the outside without the disks. Elegant solution to the space problem but a bit of drilling and grinding to get the fit snug.
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I dropped the wheels off on the weekend and hope to have the car running and registered before Brexit happens (if it ever does!) They were a pain in the arse (ass) as I kept finding new little spots of pitting and corrosion, casting bumps and holes that needed cutting off or filling... They turned out nicely from 1 meter but little imperfections that annoy me close up. Still trying to get the numbers to make up an order of coffin-spoke 16" or 17" wheels-- currently there seem to be more people wanting 16" but there are no deep 16" forged blanks so we would have to go cast which requires at least 20 sets to be viable.
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Quick couple of questions— finally had a chance to visit my 308 (work and life has been busy for a while.) I just have the 1978 parts catalog with me which is only marginally helpful.

Is there a six-blade connector I need to find that perhaps connects to pressure sensors (right of pic.) Also what is that tube sticking up in the side of the bell housing? Breather?

The shiny aluminium part testing on the cam cover is a blanking plug where the air pump pulley used to be. Let me know if you need one as I can get some more made.
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I had an idea about the mystery 6-blade connector-- might it be for the missing catalytic converter thermocouples??

I have put an arrow on the tube into the bellhousing- is this a breather? Any help much appreciated
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Thanks Joe. I must be missing the cap so will try to find one or put something porous on it.

 

Two things to report on my ongoing adventure... firstly I bought an engine and gearbox for an engineless GTB here in the UK but the car sold (to an electric converter) just after I bought the drivetrain so I decided to build it up as a spare or for sale with all the usual better parts (forged 10.5:1 pistons, cams etc.) plus some IDFs on a new manifold that I'm having made. So many people asked me to find NLA CIS parts that I thought there may be a market for IDF manifolds. Cheaper and more tuning options than the DCNF. I might do a version for the QV in case there is interest. I just got some parts back from vapour blasting and they look a bit too good! I'll sell the std pistons in case anyone needs one (or a set.)

The guy in Kent who has been tinkering with my 308 for a year is losing the space he has for it and I still haven't found space for me to work on it within an hour of London (W1B.) If anyone has some space to rent or knows of a place where I could store and work on it (electrics, put the windows in and a few other small bits and bobs), please let me know. I would also like to hear of a competent garage within a few hours of London that doesn't charge usual supercar prices as I might get someone else to finish it. I only have space for engines and parts at home, not a whole car :-(
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Thanks Brock, I suspect Wilwood doesn't want the liability of DOT approved parts so they are sold as "racing only." The failed calipers I have seen over the years have all been pistons stuck due to rust. These are a nice unsprung weight reduction and probably dissipate heat better than the old iron ones.

 

Dave, I have drawn some initial CAD files and my neighbour (with a 3D printer) is currently printing the first prototype for fitment testing (we have nearly 10kgs of filament left from printing ventilator prototype parts in the spring.) The manifold will be short enough to have a decent (85mm tall) air filter on top of the IDF or throttle body. I may put some injector bosses on the tubes as well for anyone who want the injector closer to the port. If anyone is interested in a set let me know as I'm currently negotiating MOQs and prices with both UK and China suppliers. Manifolds are likely to be about £100 and 40 IDF copies (which can go up to a 36mm venturi) will be about £500 for 4, I will also do a nice Ferrari themed air cleaner and linkage to suit.

The hieroglyphics in my drawing show the limits of Sketchup's tube bending extensions-- free but you get what you pay for

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I took the path of least resistance and paid someone
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Yes it does look more than 45 degrees and the two IDF flanges don’t look parallel or even in the same plane. Freecad render of a step file. Any thoughts on including bosses for injectors? Are there any short throttle bodies available with only the butterflies?

 

The Ti retainers I ordered finally arrived (lots of delays into the UK due to the Brexit no-deal deadline fast approaching.) They are for the standard springs or the slightly softer Opel springs that CAT cams recommends. Saves almost half the weight. I have 8 sets extra as I had to buy 10 and am keeping two sets. £160 plus post if you want a set.

My spare engine's liners and pistons are so good (all at std 81mm with no apparent wear and hone marks still in the bores) that I may just buy new rings. Has anyone used just 2 compression rings? Which grooves? thanks, derek
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Thanks Graeme, I popped two stainless plugs for the rear calliper adjusters into the post fir you. Beers on you next time!