Cortina Mk1 tech questions!

[Mike Bell]

Posting on phone in w/shop, so brief.

Standard g/box, when gets hot can't change gear. Suggested shaft in remote is too tight in housing, and this pinches it when hot. Feasible?

ARB front mounts. Do you serious racers modify from the standard clamps? Looks like threads are bad in one chassis rail.

[zefarelly]

Mike, you need to be a little more specific re gear box, is it a bolt on gt/lotus remote? A std stick is most reliable. If it's the actual box its more serious.

Re ARB mounts. They're very weak, if you clout another car they snap clean off. In fact racing hard they snap clean off too. Simon H told me that, I'm just a Sunday driver

ping me an email and I,ll send a few photo's and ideas in the morning.

[Mike Bell]

Originally Posted by zefarelly

Mike, you need to be a little more specific re gear box, is it a bolt on gt/lotus remote? A std stick is most reliable. If it's the actual box its more serious.

Re ARB mounts. They're very weak, if you clout another car they snap clean off. In fact racing hard they snap clean off too. Simon H told me that, I'm just a Sunday driver

ping me an email and I,ll send a few photo's and ideas in the morning.

Yes, Joe, it's a Lotus with bolt on remote. May have found the answer, as roll pin that holds finger onto shaft at gearbox end was half out, allowing finger to move round. Could have tried to move two rails at once....

Agree about ARB clamps. Need to do something better! Email sent....

[morninggents]

RE. the ARB. The usual trick is to fit the bar in to aluminium blocks (roughly 4&1/4 in length; 3/4 in thick; and 2&1/2 in high) which have been cut halfway up their height. Drill the blocks to the diameter of the ARB to be used (if a Lotus Cortina then standard diameter is 7/8 inch and homologated option is 15/16 inch though many, illegally in my opinion, use 1 inch and above) then drill up through the blocks and bolt to the original ARB mounting. The trick, of course, is to drill the hole for the ARB in the block forward of centre to improve the castor.

I seem to recall seeing some spares in the workshop a few months ago.

[Mike Bell]

Thanks Peter. I thought about alloy blocks, but know from Escorts that the roll bar twists and contorts a bit and was wondering if some compliance would be good.

Main issue is that one of the bolt threads is bad in the chassis rail. Think 5/16" UNC? Escort uses larger dia. Any idea if possible to drill and re-tap captive nuts to take bigger bolts?

[terence]

Mike,If one side is a little iffy wouldnt it be a good idea to cut both sides out and remake the sections but weld in ten mill nuts instead?There are poly kits available that include the clamp I think.Pretty easy job that once dane will outlast the rest of the body,use 3mm steel plate btw.

[Mike Bell]

Trouble is shell has just been restored and pristine! If it were mine I'd drill through and tube the chassis rails, same as we do on Escort X member location. Then could use through bolts. Alternative would be cut open side of chassis rail to allow new nut to be inserted.....

Main advantage of alloy clamps to me is ability to alter castor, but as this car has standard location points, TCAs and geometry at the moment, IMO needs to be tackled all in one go with some knowledge of what camber and castor are optimum......

All comes down to owners being willing get to get their wad out, I guess!

[Simon Hadfield]

Peter, anti roll bars are free - see appendix 9 of Appendix K - but the position of the wheels is not! There is a usual tolerance of 1% for dimensions in Appendix K (bizarrely 1.1% for wheelbase) so to me that means the castor cannot differ by more than 1% from the standard. Some front wheels of Lotus Cortinas are now so far forward that the front of wheel arch has to be modified to clear the wheel. Just like they were in the day.....

[zefarelly]

When mine was rearranged I had no option but to drill the old bolts out ( sheared clean off) and I went through in exactly the same position, then inserted 12mm tubes (10mm bore) and have M10 studs clean through. The ARB has to fit within this parameter IMO so can only move forward a little. I use a 24mm ARB and despite others thinking 1" is better, I like it. I have machined nylon liners so the ARB is free to roll, as opposed to being solidly mounted, and just twisting/bending.

My wing on this side is original and has never been off the car. I'm just about to re-check my geometry having tweeked a few other bits.

aim for 4-5 degrees caster and 2-3 degrees neg camber . . . . not easy, mine was 1 & zero when I first rebuilt it. Negative camber can be dialled in by re setting the strut tubes in the stub axle. caster is all about anti roll bar mountings, there are 2 ends remember. As well as top mounts, but not the inner wings obviously!

at race height the TCA's ( if they're original) will be nigh on horizontal, so I found that in compression the geometry went into positive camber, which helps explain why I shred front tyres.

Unlike some, I don't think you need to go to extremes, just some careful thought and a few subltle tweeks. The end result being a car that's fun to drive and looks right, and retains a standard bodyshell and key standard suspension components, as it should.

just my ideas of course.

[zefarelly]

front wheel location, half sensible I think . . . original wing.

oddly enough, the wing on the passenger side is not original, and the wheel appears further forward. possibly a pattern wing, was fitted before my tenure.

No idea why that's upside down, unless it was taken in the Monaco tunnel with the new aero package

[grantp]

Originally Posted by Simon Hadfield

Peter, anti roll bars are free - see appendix 9 of Appendix K - but the position of the wheels is not! There is a usual tolerance of 1% for dimensions in Appendix K (bizarrely 1.1% for wheelbase) so to me that means the castor cannot differ by more than 1% from the standard. Some front wheels of Lotus Cortinas are now so far forward that the front of wheel arch has to be modified to clear the wheel. Just like they were in the day.....

That's interesting Simon.

Were the tolerances out of the factory that good?

I recall reading a report of a chap who bought a new Mk2 Cortina and found it would turn left easily but was reluctant to turn right (or vice versa).

After about a year of "discussing" this with the dealer and Ford it was discovered that whilst everything was within manufacturing tolerance the tolerances had built up in opposite directions across the front and rear axles by about 2.5 inches.

I guess without power steering this became something of an issue, especially on roundabouts.

I had a VX Omega at one point that felt fine (given that VX steering around the straight ahead was vague and the power steering masked problems) but had a very strange tyre wear pattern that clearly meant it was crabbing along the road. All sorted out with a 4 wheel alignment and the replacement of seized adjusters.

A year later it had some engine issues. While they were being looked at I asked them to change the sump as the thread on the drain hole was damaged and it tended to leak. They then informed me that to do that they had to drop the front A frame.

When they put it back they failed to check the positioning and re-do the 4 wheel alignment. I picked it up and drove about a mile during which it became obvious that something was seriously wrong. The engine in the previously provided loan car was still warm. I left the Omega with them for another week.


Presumably it's possible to optimise a car for a circuit based on whether the most important corners are left or right handed?

[zefarelly]

MK1 Cortina bodyshells are surprisingly consistent. Out of the factory at least.

I've measured quite a few.

How they're bolted together, and what with seems to vary wildly.


1.1% on wheel base is +/- 27mm, I don't think you need to be Mr Newey in the engineering stakes to keep within that tolerance

[grantp]

Originally Posted by zefarelly

MK1 Cortina bodyshells are surprisingly consistent. Out of the factory at least.

I've measured quite a few.

How they're bolted together, and what with seems to vary wildly.


1.1% on wheel base is +/- 27mm, I don't think you need to be Mr Newey in the engineering stakes to keep within that tolerance

I was thinking more the smaller measurements at 1%.

I would assume that a competitive engineer seeking some performance improvements might well be looking to step outside the tolerances in some way without appearing to have done so. Some high ability nous might, therefore, be a requirement.

[morninggents]

Originally Posted by Simon Hadfield

Peter, anti roll bars are free - see appendix 9 of Appendix K - but the position of the wheels is not! There is a usual tolerance of 1% for dimensions in Appendix K (bizarrely 1.1% for wheelbase) so to me that means the castor cannot differ by more than 1% from the standard. Some front wheels of Lotus Cortinas are now so far forward that the front of wheel arch has to be modified to clear the wheel. Just like they were in the day.....

On rereading the App K regs I agree with you on anti-roll bars but it then makes you wonder why Ford/Lotus went to all the trouble to homologate options. (Apologies to anyone I may have besmirched by my original post). I have the App K regs effective from 01.01.15 but not the 2016 version. When you mention 'position of wheels' are you referring to the tolerances allowed under section 3.8.5 for wheelbase +or - 1.1% and 3.8.6 for track + or - 1%? If so, this would allow you to bring the front wheels forward provided the rears move forward also to keep within tolerances. However, I agree with your comment about having to modify front arches for clearance!

[Simon Hadfield]

Not so Peter, the wheel/axle centre lines may only move by 1% from the mandated position - and those are given clearly in the workshop manual - so those are pretty well fixed. As those centres are given as being from other nearby points on the body shell the rear axle can only move within 1% of that dimension, not 1% of the wheelbase.

[one-two]

Isn't this one of those cases under Appendix K where "free" doesn't mean completely free without limit. Is it not more correct to understand it as free to fit anything that was fitted in period. I am aware that established practice tends toward the first interpretation. Can Louis offer an interpretation?

[morninggents]

Originally Posted by Simon Hadfield

Not so Peter, the wheel/axle centre lines may only move by 1% from the mandated position - and those are given clearly in the workshop manual - so those are pretty well fixed. As those centres are given as being from other nearby points on the body shell the rear axle can only move within 1% of that dimension, not 1% of the wheelbase.

It's good to know that that is the case but I couldn't exactly find the appropriate wording in the 2015 App K regs.

[Simon Hadfield]

All of this needs the organiser to want to enforce the regulations. That is the point at which every thing falls down.

[zefarelly]

There also needs to be consistency across different Marques.

no point nailing Cortinas into the ground if Alfas, BMW's and minis run free.

MInis and Cortinas have been so popular as I guess they're more 'cost effective' to make competitive and clone as the desirable variant.

[one-two]

I absolutely get the point about enforcement, but the first issue is to try to understand what the rules actually are! I think most people - by which I mean competitors, preparers and, possibly, race organisers - believe ARBs are free more or less without limit. I don't believe that to be the correct reading of Appendix K, but it's quite possible I am mistaken.

[Mike Bell]

When asking the original questions it was never my intention to stir up any nests of stinging insects! Just shows how feelings run strong among the historic racing community.

The car in question now has alloy blocks to hold the ARB, as pictured by Joe earlier. I've drilled out both bad threads in the chassis rail and fitted timeserts for now. Just waiting for some long bolts to hold the blocks on! This will get the car back on track for testing, until time to 'tube' the chassis rails, which is still my preferred choice.

The gearchange remote has been inspected, fettled, new roll pin fitted, shaft polished and reassembled on the box. When car is back on its wheels will be able to find out if all the gears are there.....

Thanks all for your help- and carry on......

[one-two]

Sorry to gate-crash your thread Mike!

[Mike Bell]

Originally Posted by one-two

Sorry to gate-crash your thread Mike!

No problem, help yourselves- I'm off back to the workshop!

[zefarelly]

watch those ARB mounts, the captive nuts are spot welded to a strengthening plate inside the box section, its pretty weak even for a standard car.

[Mike Bell]

Originally Posted by zefarelly

watch those ARB mounts, the captive nuts are spot welded to a strengthening plate inside the box section, its pretty weak even for a standard car.

Yes, remember from Escorts! Anyway, the timeserts went in fine and the car is back on its wheels. Had to fit the original brackets though as the 3" bolts for the ally blocks didn't turn up....

Can't find reverse! I thought to the right and down? Guess something to do with the remote and that adjustable nylon block underneath.....