MkII Cortina Perana V6 racer

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Re: MkII Cortina Perana V6 racer

Post by KSF » Wed 09 Nov 2016, 17:13

With the front end basically together, I left the arch flare in that rough shape and started looking at the rear of the car. That had to also be completed with wheels on to see how it all worked out. I did not want to use the OEM diff. They are good in that you get quite a few ratios in the range that is suitable, but they are at the end of the day not really strong enough for the bigger engine and slick tyres. Also, my track width at the front was now wider than stock, so a wider diff would work out better.

The one I chose to use was again the BW M75 out of the Cortina 3.0l one-tonner bakkie. They have a 4.0:1 ratio which is close to what I want (and other ratio's available too), they are quite strong with thick sideshafts and are just about the right width to match the 'Sierra' track at the front. In addition, they are not quite as heavy as the later model M75's popularly used on SA's bakkies and the Toyota Ventures.

I got hold of one earlier, I forget now if it was through the forum or through Gumtree. Maybe it was through Gumtree and turned out to be a forum member, something along those lines.
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By rule diffs and their ratios are free, LS and locking allowed. I will probably run it with the 4.0 and in open state as a start, to be adjusted/changed once it has run to see what it needs.

Getting it to fit meant chopping off the spring support, much wider and also bigger than the Cortina items. In this case I also carefully removed the ones from the Cortina (car) diff and welded it to the Cortina (bakkie) diff. They include the shock mountings for the car, so it makes that a bit easier. I also learnt to mock the whole lot up in the car before welding it. Otherwise you have to work very carefully and accurately to get their alignment spot-on, something not as easy it it might sound.

Below the only pic I have of all that. Think I took it as a reminder of which way round it sits on the OEM diff.
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So the diff went in and wheels went on. I left out the bit where I spent a whole Saturday de-radiusing the leave springs. No pics in any case.
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It worked out just about right (note these are still semi-slicks from another car, will be replaced later.) for the width I wanted. Also turned out to be a bit wider than the track at the front, but I would rather fix that at the front than shortening that diff. Non-standard parts means more problems finding replacements and more costs etc and so on.
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Re: MkII Cortina Perana V6 racer

Post by KSF » Wed 09 Nov 2016, 17:39

About this time something happened that I had to move the car from that spot to another, but I forget what it was. It meant propping up the rear suspension to get the arches off the wheels so I could push the car. The front was OK as it sat on the bump stops in any case.
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Fairly low too, the top of the mudguard here was just about against my knee.
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Settled into the new spot, work could start on flaring the rear arches. Here I am taking a bit of a liberty as I dont think the original car had very big flares at the back. It did have flares, but mine are probably a inch wider. The look and shape I tried to copy best I could.

Here some of the measuring and markings with the cardboard pattern/template still attached.
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Once both side were marked and the cuts made, the fun starts. Looks good already, maybe a can or two of fibrespan and some light sanding!
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The rears are tougher to do, they are double skinned and there is the proximity of the rear door to worry about. I cut the inners skins more after this pic, trimmed their ends shorter and then bent them up till they meet the outer skin again (after that is shaped). Where they meet the inner gets welded to the outer to keep it in position and give back the strength to that rear quarter. Dont think I have any pics of that operation.

Then same as at the front, it gets shaped and bent into the flare.

This was the first rough shape.
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It did not look right and some more shaping was done, at the end also trimmed the tabs/tongues/leafs shorter, then it looked better.
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Happy with this basic shape, it is over to the other side to copy it.
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With both done, finally the car gets put down on its wheels to check clearances and so on.
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Re: MkII Cortina Perana V6 racer

Post by KSF » Thu 10 Nov 2016, 17:41

As can be seen in this pic below, the difference between front and rear track was significant. In part because it turned out I had far too much camber at the front.
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I did measure it during mock-up to find the right spot for the strut top to go, but as usual once the full weight of the car and engine was on it, it settled out quite a bit more than expected. Also, I had to move the lower control attachment even more to the outside to match the rear track. With that done, the camber had to be adjusted/corrected at the top. Given the way I welded in the top, adjustment meant cutting, moving and welding it into a new position. The camber plate fans might now be breathing in to say "I told you so", but before you do, I had to move it so much I doubt any camber plate would have allowed that much.

Pic below after the cut&paste&weld. Again this was after the first run and clean up. Thicker stuff was OK, thin stuff again a problem that required going back and fixing.
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This corrected the track and got the camber to within the desired range. Pic below of the all important stance after the adjustment.
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Closer up of the front wheel.
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At this rideheight the underside gets to be a bit close for comfort, especially as I will be using a wet sump.
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By the new rules, I still have to add a drip tray under the sump, then clearance gets critical. Maybe ultimately let it ride 20mm or so higher. In any case, at the back now the bump stops are already removed and the diff pipe is a mere 25mm away from the underside of the chassis beam. That is not enough and it will bottom out, so need a bit more there too and I don't wish to start chopping into the chassis.

In the pic above you can see the next challenge lurking, the rust repair. A clear hole in the chassis beam is visible there. And I was running out of excuses and other things to do, could no longer postpone it.

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Re: MkII Cortina Perana V6 racer

Post by Killarney Racer » Thu 10 Nov 2016, 18:47

KSF, this is a fantastic job. When I saw that car in your garage I thought it may be a bridge too far to get a KS replica out of it. I was wrong. I take my hat off to you and look forward to seeing the car on the track. Well done!

And a good read too ;)

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Re: MkII Cortina Perana V6 racer

Post by Shauns » Fri 11 Nov 2016, 11:38

Awesome Build , Loving the pics .
Keep em coming
2014 Toyota Fortuner D4D (current)
2005 Toyota Tazz 130 (current)
1989 Ford Sapphire 2.0i GLE - FSH - Grosvenor Pinetown - In Storage for now.
1977 Ford Mk 2 Escort 4 door - Kent Screamer - In progress

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Re: MkII Cortina Perana V6 racer

Post by KSF » Fri 11 Nov 2016, 16:43

Killarney Racer wrote: When I saw that car in your garage I thought it may be a bridge too far to....
You are not the only one! I sat looking at it often enough wondering what I got myself into.

Tx guys, I will keep waffling away and post more pics. The thread is still catching up to the present and roughly halfway through the available pics. Once it has caught up, the post rate will drop dramatically. Wish I really could build this fast! :lol:

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Re: MkII Cortina Perana V6 racer

Post by KSF » Fri 11 Nov 2016, 17:13

So the rust repair. This is a bit of this build I did not enjoy much at all. Initially when I cleared off the sound padding, I believed it may be possible to just replace sheet metal on the floor in localized areas, then thoroughly clean the rest, rust convert it and give the whole floor a layer or two of GF matting and resin. It strengthens up the whole monocogue in any case (guys who followed drag racing back in the 1990's might remember Sybie Coetzee's very quick red and later orange Datsun with the turbo/Nos V6. He did just that to strengthen the floor and it worked). The 'only' really bad bits was that front right area and also the valleys in the rear footwells. Valleys as in the bottoms of those indentations.

But then that hole appeared in the chassis beam as it goes up to the engine bay area. It might have always been there, but I then crawled in under the car with pliers, hammer and screw driver to go check the rest of the beams and found that although they mostly looked really good from the outside, it was just a very thin skin on the outside that somehow retained its good looks. Inside it was rotten. Also, there was not one section where it was good on both sides of the car. I probably have mild OCD, but the idea of one half a repair and the other original would drive me nuts, so it all had to go.

After probably another 2 weeks of procrastinating, wondering, asking for ideas, one day after work I decided to just go and cut it all out and take it from there.
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I did take out that back bit first, just in case I make a mess, it would be the easier one to fix. But, in for a penny, in for a pound, no point wondering any more.
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Front out. On the floor next to the car is the bit chopped out and one can clearly see just how bad the beams and floor panel had rusted.

There was a pause here in the project. I wanted to see (although I had very little hope of success) if I could find a donor car being chopped up anyway to get a good floor out of. No such luck, the few that were bad enough to chop up had floors even worse than mine. I had a look at some other cars to try and find something one could make fit. I gave up on that idea, again he cars in my area (Western Cape) getting chopped are rusted. Scrappers were not much help either, in any case more modern cars have floors of a quite different size and shape, so it would be too messy. I did, for about 10secs, think about trying to source replacement panels from UK or such, but the cost just cannot be justified for this type of project. Perhaps a nuts and bolts concourse type restoration yes.

So, I set about getting materials together to fabricate replacement parts. Don't set your sights too high, I am not one of those highly skilled guys who can shape sheetmetal into the OEM shapes, this was going to be a lot more brown beef stew than fillet mignon.
Last edited by KSF on Fri 11 Nov 2016, 17:36, edited 1 time in total.

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Re: MkII Cortina Perana V6 racer

Post by KSF » Fri 11 Nov 2016, 17:34

I got hold of some steel section and plate, a nice size just bigger than the OEM bits and the plate a healthy 1.4mm. Nice thickness to easily shape and thick enough to weld properly.

First some plate along the inside of the sill below the door. There some holes had appeared towards the front, but I wanted this full strength along most of the side. Then the 50x50 squares cut into lengths to replace the beams. During this initial trial fit/mock-up I made liberal use of aluminium pop rivets to keep it all in place and aligned.
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..and a bit of masking tape I see.
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These were all tacked in place sort of as I go along, then the next piece is cut and trimmed to suit/fit.

For the front of the main chassis beam were it turns upwards and gets wider, I fabricated a piece out of the sheet metal cut to shape and welded together.
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This was then also put in place on the car and tacked to the sq tubing.
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With all the bits together and tacked, the whole assembly gets removed, rivets drilled out etc. I did this so I could get at all the angles and joints properly with my stick welding.
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Done and ready to go back in.
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This process was repeated for the left side.

Both then put back in place and welded in and onto everything close enough. There is a bit missing from the pictures, the member at the back also curls upwards and follows the inside line of the tunnel under the car. There I made up a piece in the same fashion as the bit at the front and welded it in. Like roughly two horseshoe shape plates with a third plate between then. So it ends as a U-profile.

I wont relate the frustration and swear words of being upside down under the car trying to get decent welds in. It is still a painfull memory I am trying to supress. :( :lol:

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Re: MkII Cortina Perana V6 racer

Post by KSF » Mon 14 Nov 2016, 16:23

Next challenge was the floor plates themselves. The sections I had cut out were largely flat plates, just with the usual patterns pressed in. I had wanted to try and copy that, even if not the exact same patterns, I wanted to get some profiles in to stiffen the plate a bit. That way one can use a thinner plate and get the same rigidity. In the end that just did not want to work out, I could not do that myself and I could not find the right person to help. So flat plates it was to be. I did order from my local some 0.9mm plate, not thinking to specify anything else. Turns out their std 0.9mm plate is galvanized, so by the time I realized this, it was cut to size, paid for and in fact delivered.

I guess it does have advantages, but welding on it is not one of them. It also put paid to any notions I might have had of brazing it in areas where I struggle with welding. Brazing and galv are not friends at all. I also don't like the way you struggle to get primers to properly stick to galv. So, flat galvanized plates had to go in.

I did the final cutting and trimming, around the edges where they need to curve to get into corners I made some cuts to aid with the shaping. These were all to be welded up once it is all in place. Again I started in the rear footwells, smaller and easier.
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They were cut some 25mm bigger that the hole, so you get a lap joint, not a buttweld. It also allowed the use of pop rivets to keep it flat and in place during welding. In the pic above was the first bit of stitch welding and things went reasonable OK.

That was also about where the good news ended. I never even took pics of it, but as I progressed further from there with the stitchwelds, it just went from OK to impossible in about 10mins. The problem seemed to be that where the original plate gets pressed into complex curves and the like, it thinned quite a lot. I never measured it, but where the rest is a nominal 0.8-1mm, in those places I guess maybe 0.6mm. It was just impossible to weld with stick.

Progress and the project as a whole ground to a halt again.

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Re: MkII Cortina Perana V6 racer

Post by KSF » Mon 14 Nov 2016, 16:54

I have to take a little detour here, bear with me, normal service with lots of pics will resume.

Up to here the project had gone much slower than I anticipated, it was now (this was Sept/Oct 2015 already) clear that 2015 was once again not the year I would make it back to racing. In fact, 2016 had started to look like a tall order. (since proved correct). So when I got bogged down struggling a bit with this rust repair, especially after some other struggles on this project causing delays, I got a bit fed-up. Right then I would have given a lot to have a rust free project of any kind.

So, when I heard that the Classic section was considering adding a pre-87 class for the following season (2016), I was all ears. This was an age group of cars still in plentiful supply and with a bit of searching, chances were good to get a clean example that will not need major repairs to bodywork. Back then, the rules for pre-87 was still being written, but it was to be largely the same as pre-77 Classics, except maybe on semi's instead of full slicks. So immediately I started looking for a car. Clean Cortina MkV or Sierra I. I wrote off Cortina MkV's very quickly. They have turned into gold apparently. So Sierra it was to be and I was very fortunate to get hold of a largely unmolested XR6 that was recently bought upcountry and brought down here. So I grabbed it.
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For those who know Sierra's, many if not most had rust issues where the anti-roll bar gets mounted. See here, this car is clean as it roll out the showroom 30 years ago.
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So for a couple weeks, it was all about finding, buying and bringing home the Sierra. Also at that time, I started gathering up some bits and pieces I would need to complete it. However, this car turned out to be so unmolested and in fact quite close to completely std, that I wondered if it would not be a waste to strip it out for racing. It did need a fair bit of work to get the mechanicals in good condition, but the biggest thing to make it properly original, was the driver's seat. It had been replaced with a Sapphire seat and I could not find the right seat at all. I did advertise on here and in the end did a deal with member wanegofast where he took my left seat for his project in exchange for some parts I needed. That sort of decided it, racing car it was to be, but since the rules for pre-87 was still under construction, work could not start. It also started to become increasingly likely that the rules would not allow flared arches, it felt to me that the difference between pre-87 and Fines would be a bit too subtle. Fines would also allow me to keep the XR6 bits as they are and keep it a roadgoing car.

In any case, I decided to rather leave it parked as is untill the rules are fixed and firm. That only happened much later that year, so in the mean time I went back to the Cortina project.

Below some more Sierra pics. The insides was really very dirty.
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