Suspension preparation for classic rallying

[MalcolmSp]

Hi,

I've been into Minis for a few years - well, since 1965 to be precise! Currently I have three minis, a 1963 1071 Cooper S and two 1959 minis.

I have rebuilt one of the 1959 minis with the intention of rallying it, but have limited experience of such builds! My son and I took it on Friday to Throckmorton for the HERO one day challenge on Saturday, but managed to break a front suspension cone just doing a "driving test". So I have realised that I need to do a lot more strengthening and suspension preparation to prepare it for the next event.

If there are any esperienced Mini rally drivers out there who could give me some tips on suspension mods, I would be extremely grateful.

(The car itself is underpowered, as I have kept to strict 1959 mini engine mods, so it has just standard mini valves, but produces about 47 BHp using twin H1 SUs on an early Downton manifold and a 731 camshaft)

Thanks for any advice you can give,
Malcolm

[Cooperman]

On my Historic 1964 Cooper 'S' I run the following:

SPAX adjustable dampers front & rear
Adjustable front tie-bars
1.5 Degree negative camber lower arms
Competition lower arm inner bushes
Front tie-bar brackets reinforced with triangular 1/8" steel plates to prevent them from bending.
Long track-rod ends
Front track set to 1 mm toe-out
Caster set to 3.5 degrees
Hi-Lo front trumpets
Ride height set to 1/4" higher than standard
Rear ride height set to 1/4" higher than standard using Hi-Lo's
Rear track set to 1 mm to 2 mm toe-in and zero to 0.5 degrees negative camber (I do this by filing the holes in the radius arm end plate and welding a large washer at the correct settings).

PM me if you need any more information.

[MalcolmSp]

Thanks, Cooperman, just the sort of detailed advice I wanted. I will almost certainly follow your example.
When you say that you increase the ride height by 1/4" are you referring to height at the trumpet or actual car height?
Also, do you use a sump-guard? I haven't fitted one yet, as I'm trying to save weight, as my standard mini is obviously very under-powered. But if you consider it essential, I'll probably fit one.

Thanks,
Malcolm

[Cooperman]

I would never rally without a sump guard. I'm fortunate as I obtained an all-alloy substantial welded guard a few years ago and it's very light.
With a sump guard you will need an oil cooler.
Here is my 'S' on a test on the East Anglian Classic a few years ago. We won.

[MalcolmSp]

Thanks again for the advice - which confirms my suspicions. Reluctantly i will add the extra weight to the car.

Malcolm

[sprocketman01]

Pack the space between the sump guard and the sump with polystyrene to stop any stones getting inbetween and smashing the sump!!

[Cooperman]

That is really only necessary on forest stage events. On tarmac it is better to get the airflow between sump underside and inside face of sump guard.
Foam sponge is what the 'works' used to use.

[FWDRacer]

Drop the front and rear subframes and seam weld them in addition to the tie bar reinforcement mods Pete has mentioned. Gusset the rear subby with triangulation in the corners. Are your fuel/brake lines inside the car? Recommended.

[MalcolmSp]

Thanks for the further details, guys, much appreciated!

Sadly when I rebuilt the car, I didn't put the lines inside, naively thinking that these retrospective rallies were a bit gentler than that. So, if I am now going to strenthen both subframes, I might just as well run the lines inside at the same time.

If you think of anything else, do let me know - as I can see that I've got some major work to do on the car! I want to get it right for the next event.

Thanks again,
Malcolm

I've attached an early underbonnet photo. Since then I've sealed the bulkhead and fitted an auxiliary fuel pump & spare coil.

[NotNormal]

Can't help directly with the question however, if you are not aware already, this is the best place for early Mini advice and info.

http://mk1-forum.net/index.php

Some very knowledgeable people on there

[Cooperman]

For UK Historic events it is not really necessary to strengthen the rear sub-frame (unless it is a 'pattern' one). One place to add a small triangular plate is at the top of the rear radius arm brackets.
Apart from the tie-bar ears the front is pretty good as well, but it can be good to weld a doubler plate under the flat area beneath the lower arm fixing. This helps with jacking/support.
Yes, run brake fuel and battery lines inside - I think I sort-of assumed that had already been done.
For reliability it's a good idea to fit twin Facit electric pumps, wired separately and with separate fuses and switches. Then a fuel pressure valve is needed.

[FWDRacer]

Rear radius arm brackets - reinforcement on the top via a triangulation - good call! Genuine ones are much stronger than aftermarket crud due to more generous bend radii and thicker gauge.

[Cooperman]

I always fit a battery box shield made from 4 or 5 mm thick aluminium sheet. The outer edge I shape to bolt onto the sub-frame inner edge and I rivet a strip of aluminium angle, about 25 mm x 25 mm x 4 mm thick along the inside edge. I bolt the front through the floor using some bath sealer and make up a detachable bracket at the back to bolt it to the rear sub-frame cross member.
Extra exhaust mountings are also advised plus some check wires around the back of the exhaust in case the rubber mountings fail (as they do!).
By the way, I used to rally in an ex-works prepared 850 Mini. Google 'Mini 16BOJ' for photos, etc.

[Cooperman]

I always fit a battery box shield made from 4 or 5 mm thick aluminium sheet. The outer edge I shape to bolt onto the sub-frame inner edge and I rivet a strip of aluminium angle, about 25 mm x 25 mm x 4 mm thick along the inside edge. I bolt the front through the floor using some bath sealer and make up a detachable bracket at the back to bolt it to the rear sub-frame cross member.
Extra exhaust mountings are also advised plus some check wires around the back of the exhaust in case the rubber mountings fail (as they do!).
By the way, I used to rally in an ex-works prepared 850 Mini. Google 'Mini 16BOJ' for photos, etc.
Do you have Perspex windows all round except the windscreen? If you don't they are the best way to lose weight.

[MalcolmSp]

Thanks again Cooperman - I'm almost getting overwhelmed with advice! If you think I can get away without welding up the front subframe, I would prefer it - I hate taking out engines!

Yes I have got perspex all round except for the windscreen. Also fibreglass bootlid and bonnet and no front bumper - although I realise that is strictly illegal, but the bumper flange had been removed years ago and HERO seem to turn a blind eye to missing bumpers.

I have also fitted an auxilliary SU petrol pump in the engine compartment, next to the wiper motor. It seems to work fine there.

I was fascinated by your accounts of rallying in the 60s. I wonder if you can help - my intention behind using a 59 car was to get into the "50s" decade, so that a standard mini is a bit more competitive than in the 60s. But with your experience of rallying an 850, do you know whether there were any larger valves available in 1959? Checking on other BMC cars using the A-series engine, they all used the same valve size as mini. But surely the works 850s had larger valves? I don't want to cheat, but I know I could get a lot more power out of mine if I can increase valve size.

Thanks,
Malcolm

[Cooperman]

Hi Malcolm,

I think the homologation as in early 1960's didn't have any larger inlet valves. The big problem was the combustion chambers and the valves do need substantial de-shrouding. Maybe a set of 997 or 998 Cooper inlets would fit well and I'm sure you would get away with these.
The big issue with the 850 is and always has been the weak crankshaft, especially the very early ones with oil fed primary gear and thin crank tail, although your may have had a later engine fitted already. If it hasn't, then find a later 850 engine and do the work on that as the 1959 - 60 engines are really very poor. There used to be a comp. crank for the 850, but I doubt you'll ever find one now.
The other issue is the camshaft which ran in the block with no cam bearings. However, a lot of blocks had cam bearings fitted when a re-bore was needed.
The best thing to do would be to find a 12G940 head and set the car up with that, but you would need to skim a lot off to get sufficient comp. ratio and you would need to find some flat-top pistons.
The front sub-frame won't need any additional welding so long as the triangular stiffeners are fitted to the tie-bar ears. if you want a photo of these let me have your personal email and I'll send one.
The other thing I would mention is the need to cut a rectangular hole in the rear seat back panel to allow the LH damper to be changed without taking the fuel tank out. You then fit an aluminium plate to seal the hole which should be about 3" x 5". Again, if you want a photo of where to cut it I can send one.
By the way, electric fuel pumps 'push' the petrol through the line better than they 'suck' it, so it is best to fit the pumps at the rear under the rear horizontal seat panel inside the sub-frame.

I hope all this helps.

Peter

[MalcolmSp]

Hi Peter,

Yes, I was aware of the frail early cranks (I've got one and I think I've seen 'em described as "a piece of bent wire"!) So I used the later crank and removed excess weight and polished it and con-rods etc which were all balanced to less than a gram. I also managed to find some rare Hepolite raised top race pistons, which I used. I've had cam-bearings fitted and it runs on a 731 camshaft - surprisingly smooth pick-up, though it's only 10:1 compression, so the power is low.

I would certainly like to fit 997 Cooper valves or a 940 head, but I feel sure I would be penalised and end up with the car homologated as 1960s.

I'm sure you are right about the fuel pumps, though my wife has a Morris Minor with high level pump on the scuttle, so I might just change to the MM pump.

Whereabouts are you in Cambridgeshire? I live at Isleham, roughly mid-way between Ely and Newmarket. I'd like to meet. My personal email is [e-mail] I shall however be in India on a research trip for three weeks from Monday evening!

Again, many thanks for the advice.
Malcolm

[Cooperman]

Hi Malcolm,

First I apologise for giving the incorrect head casting number. I should have said a 12G295, not 940.

I'm just down the road at Earith so not far at all.

When you return from India give me a call and we can meet up, or you can come and take a look at my historic Cooper 'S'. If you find that you need an 850 engine I have one from a 1966 car which I could sell complete with gearbox if you would be interest.

Have a safe trip,

Peter

[Mudhen]

Awesome thread - thanks for all this great info!

One thing I didn't see...what cones are you using?

(will feel really stupid if something in the list of what you've done eliminates the need for them...my only Mini experience up to this point is Hydrolastic but I'm building up a dry car for rallying now).

Thanks again,

Pat

[Cooperman]

The 'as original' cones as sold by Mini Spares are really OK, although they do offer a 'red' cone which should work well, although I've not used them.
Best to raise the car by around 1 cm from standard then it is not necessary to have the dampers too stiff and the suspension can work better.