Historic Forest Stage Rally 124 Spider

Non-engine, eg: aerodynamics, gearboxes, brakes, suspension
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Rallyroller
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Re: Historic Forest Stage Rally 124 Spider

Post by Rallyroller » October 25th, 2011, 7:11 pm

Due to work commitments there has not been any substantial progress. I fitted the narrow plastic wheel arch extensions. Only now have U I seen what repairs have been carried out on the rear wheel arches! The fuel tank is being made, as is the new alloy radiator. When they are fitted, the car should be nearly ready to go back to the body shop for final welding and paint work.
Going back to front cross member problems, see picture attached of the current one. I hate to think what it was like to drive!
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So I now have another problem regarding oil cooler location. Firstly size is an issue. Can it be too big? ( Assuming a thermostat is fitted) . In Guys “bible” it states 16 row up to around 180 bhp. I assume this figure is for a cooler in good air flow. This is where it gets complicated.( Well for me anyway)
Ideal place is in good unrestricted air flow. If it is in front of the radiator there will be a slight decrease in overall performance as air heated by the oil cooler would pass through the radiator. However at most speeds, this would be insignificant. Also if in front of the radiator then if the fan is running there should be some effect on the oil cooling as well due to the air flow even when stationary. As this is a forest rally car the mounting location becomes important as there is more chance of damage. (Well with my driving there is). Even a slight off into a ditch or bushes/trees can easily allow branches etc to penetrate the grill. Placing the oil cooler in front of the radiator is not ideal. You could have a larger radiator but with more protection (heavy gauge mesh etc) but this could lead to other cooling problem due to restricting overall f air flow through the radiator.
Studying Mick Woods works car, the oil cooler is mounted on the nearside inner wing ( UK near side) . The air is ducted from the near side of the radiator (ie the metal on the front panel between the radiator and the inner wing is removed) is ducted over the radiator, and then the air is ducted under the near side wing and exits at the back of the front wheel arch. This obviously works, but there is the chance that ducting under the wing could be damaged on a forest stage. Worst case a stone could go through the radiator from under the wheel arch.
The other thing to consider with this location is actual air flow. A 16 row oil cooler has a surface area open for air of 300cm sq. The size of aperture at the side of the radiator is around 260 cm sq. Then add into the equation the restriction of the flow due to sharp turns required to direct flow through the radiator and then back along the ducting to the outlet vent. This will reduce the efficiency.
The simple answer would be to increase the size of the radiator.( I think Micks car has a 23 row cooler). As the air input is relatively unrestricted, and there will be a ram effect, then this would work in most cases, and as the works used it should be well proven. This installation only requires suitably strong under wing protection to work. A small electric fan could be fitted as well, but I think that if the whole oil/water cooling is designed correctly, the radiator fan should be sufficient.
As I don’t think oil cooler location is tightly regulated in the MSA rules I was thinking of other possible solutions. Can anybody see any problem with having 2 smaller oil coolers? As the area each side of the radiator is the same, 2 smaller radiators could be installed mounted either side of radiator. If this is ok would they be fitted in parallel or series? Series I would presume. With 2 small radiators in this location it would also be possible to deflect air flow down to the bottom of the engine compartment and away past the sump guard, or perhaps out of the bonnet in a low pressure area. I suppose with 2 radiators you have twice the chance to get a hole in one. Anyway your views and experience would be appreciated
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mickwood
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Re: Historic Forest Stage Rally 124 Spider

Post by mickwood » October 26th, 2011, 10:56 am

Nigel - Good to meet on Saturday

You post has set me thinking again about the best solution for your car.

One thought - early works 124s certainly used an oil cooler that was in some way integrated with the radiator itself. It may have even included some kind of heat exchanger. (i will post a copy of the Abarth "flyer" page iwhich shows this option if i get the chance). I am not sure why they moved away from that, probably they found the cooling was marginal.
However, since you are planning to use an aluminium radiator (with presumably a thicker core), and in uk forest events (not subject to the same heat extremes as continental tarmac), maybe an integrated heat exchanger would be a solution (and you can point to the "flyer" to support "period use").

Of course, this means a cancel and re-order of your radiator.

Rallyroller
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Re: Historic Forest Stage Rally 124 Spider

Post by Rallyroller » October 26th, 2011, 7:17 pm

Hi Mick

good point- I have the Arbarth flier you are on about. Height could be an issue, but the 1976 shell I have already has a deeper radiator, which means that the antirollbar has a kink in it. A standard bar could be used, and spaced down as on your car. Maybe the altenator bolt would still be a problem, but I am sure there could be other ways around that.

Dont a lot of newer cars have oil raditors iin the base of the water radiator? Perhaps for auto transmission cars. Not sure if a standard one of these would withstand engine pressure. I will be onto the rad makers first thing in the morning.
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TomLouwrier
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Re: Historic Forest Stage Rally 124 Spider

Post by TomLouwrier » October 27th, 2011, 1:34 pm

If you're going to fit two oil coolers, they should be in parallel, not in series. There's practically no way of determining their capacity when they're in series.
As a bonus: you may fit a ball valve before/after each cooler to isolate it in case of damage, keeping the other one in use (if undamaged of course).

regards
Tom
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Guy Croft
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Re: Historic Forest Stage Rally 124 Spider

Post by Guy Croft » October 27th, 2011, 3:01 pm

..see any problem with having 2 smaller oil coolers"

yes - pressure drop in the system. Avoid!

G

Rallyroller
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Re: Historic Forest Stage Rally 124 Spider

Post by Rallyroller » October 27th, 2011, 5:03 pm

Thanks guys

All very good points. As this was always going to be some sort of comprimise, I think it narrows down to 2 alternatives-
1. oil rad in front of water radiator with protection of some sort- may have to go for larger oil rad to take into acocunt any reduction in air flow due to protection gauze.

2. Fit in inner wing ( as per works cars) and ensure decent protection for rad and pipes.

Modified rad wiith intregal oil cooler not possible now as new radiator nearly complete.

I think I will also look at the front air intakes etc regarding air flow ( and stones!) along with protecting the engine in water splashes. Examination of these problems area may also have an influence on the oil rad position.
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Rallyroller
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Re: Historic Forest Stage Rally 124 Spider

Post by Rallyroller » November 2nd, 2011, 8:30 pm

I have had a look at the possible oil radiator installation and I am leaning towards the works type i.e on the inner wing. The advantages outweigh the disadvantages. I suspect that due to possible restricted flow a slightly larger cooler will be required. While carrying out some measurements another option came up.
If the engine is only producing max 180 bhp- then a 16 row cooler, in good air flow should cope. It would be possible, with slight modification to the inner wing, to mount, a 16 row cooler vertically next to the radiator. Air flow through the oil radiator would be good, ( ie no significant loss due to direction changes, laminar flow etc) and air flow out would be via the lower part of the engine compartment. This assumes sufficient air flow when the sump guard is in place. I have seen a number of racing cars with oil radiators mounted vertically in side pods. Looking at these installations, they seem to be standard type oil radiators with the flow then running top to bottom, rather than side to side on a horizontally mounted rad. Any views on the feasibility of this option?
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Rallyroller
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Re: Historic Forest Stage Rally 124 Spider

Post by Rallyroller » July 25th, 2012, 6:47 pm

Well after some unforeseen and self inflicted delays I finally have the shell back in the garage ready to start assembly. The rest of the panels should be here this week.
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The pictures show the shell when it was returned. ( Old suspension on it just to enable loading onto the trailer.) I am reasonably please with the results. Again – you learn by your mistakes. I now know that having the shell chemically stripped would have been better and overall cheaper. At the start it seemed that spending £1000+ on chemical strip seemed extravagant, now it appears it would have actually been cheaper and would have given a better finish to the interior, boot, engine bay etc. Still it is going to be a working rally car not a show car so the finish is more than adequate ,and certainly better than many rally cars but not Mick Woods fine example though.

The tank is in position so that I can start to position the pumps and filter.
In the engine bay you will see the oil cooler mounted vertically on the inner wing. There is a recess welded into the inner wing to hold it. You may just see the small hole cut afterwards to allow the top wishbone bolt to be removed! A small plate will cover the hole. (Not my miscalculation- but I’m not sure I would have done any better.)

The front end is ready for new radiator mountings. I had the extra lights put into the grill as per the works cars. Having seen the work that has gone into (and the cost) I am not sure I would bother next time.

At least having the shell back now gives me the chance to do many of the little jobs when I have a spare 5 minutes, so hopefully progress will be a bit more rapid now.

I have been trying to do some work on other parts of the car. The wiring is somewhere near now. I used the existing left hand drive loom from the 76 USA doner car as a base. I now realise this was a mistake. It would have been much easier to start from scratch. I underestimated the complexity of the “extras” on the USA model over the European spec car. Still it’s getting there now. There is a lot of new stuff in there, and nearly all connectors and terminals are new.

I am looking forward to the assembly. I do not underestimate the amount of work required, and I am sure there will be a few more headaches along the way. Little things like engine, gearbox and all the little things you overlook.
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WhizzMan
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Re: Historic Forest Stage Rally 124 Spider

Post by WhizzMan » July 28th, 2012, 10:50 am

Good to see an update here. The pictures may be flattering, but I don't see a lot "wrong" with this shell at all, I'd be proud to own this myself.
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Daveyboy
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Re: Historic Forest Stage Rally 124 Spider

Post by Daveyboy » August 3rd, 2012, 3:20 pm

Regarding the drawbacks of your fragile air cooled oil radiator, how about fitting a water cooled Laminova oil cooler? As it is water cooled it has now requirement for airflow and therefore it can be tucked away almost anywhere in the engine bay. Its virtually indestructible and its fully dismantleable for cleaning after a blow-up etc. It just goes into the top water hose from the radiator and has a take off either side at 90 degrees to the flow of the water through the main body of the cooler. They are available with various sizes of connections for the water hoses and the oil fittings are BSP or JIC in numerous sizes too. If increased/decreased cooling is required then you specify a larger or smaller cooler body. They are supplied by a very helpful UK company and if Guy has no objections I'll post up their contact details (Although I'm sure they are listed in the useful contacts/links section)
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Rallyroller
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Re: Historic Forest Stage Rally 124 Spider

Post by Rallyroller » August 5th, 2012, 7:20 pm

Interesting option. Looking at the overall context, if you are trying to reduce engine temperature you need to cool water and oil. If the normal oil cooler is in air flow then a cooling effect will be achieved. If you are using a water cooled oil cooler then I would expect that you need extra water cooling capacity to provide the increased cooling. In my case the aluminium radiator should give the extra cooling required. I will investigate.

Regarding the current position of the air oil cooler mounted vertically on the inner wing, I have just seen an article on the original London Sydney Marathon cars. It appears the works Lotus Cortinas had oil coolers in the same position.
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Simon
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Re: Historic Forest Stage Rally 124 Spider

Post by Simon » August 8th, 2012, 12:15 am

Great to see this project coming together, keep up the good work! Can't wait to see it on the stages.
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Guy Croft
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Re: Historic Forest Stage Rally 124 Spider

Post by Guy Croft » August 30th, 2012, 12:10 pm

Irrespective of how oil and water cooling systems are structured the bonnet hood on that vehicle needs spacious rearward facing louvres and a well-sealed undertray/bashplate or the heat will never disperse.

Forget the works forward facing ones, almost useless.

Fully sealed air intake from spoiler is a must-have.

Jim post the link by all means - likely is Think Auto..?

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Daveyboy
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Re: Historic Forest Stage Rally 124 Spider

Post by Daveyboy » August 30th, 2012, 4:52 pm

Yes, as Guy said, Think Auto in Isleworth, a very helpful bunch of chaps.
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Rallyroller
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Re: Historic Forest Stage Rally 124 Spider

Post by Rallyroller » January 18th, 2013, 5:58 pm

Well it has been a few months since my last update. Progress has been a bit slow mainly due to work commitments. One pleasant diversion was the Roger Albert Clark Rally. We (my co driver) and I ended up being management service crew for a French entered 124 Abarth. A long story but a great weekend, and fantastic seeing a spider out on the stages. It had a lot of attention and gave me a push to get working on mine.

The little progress made has been on the axle and front suspension.

The front suspension has been cleaned and strengthened where required. The front cross member was seam welded and plated. The inner wishbone mounts were strengthened. The engine mounts have been plated by adding 3mm plate on the underside and welding at both ends. A web was also welded in place to strengthen the mount. Hard Escort rubber mounts will be used. I had intended using Escort Group 4 mount design located on the chassis but time dictated a less time consuming approach. My original rally Spider was ok with the standard mounting with stronger rubbers but after a many seasons the plate on the cross member that the engine mount bolts to started to split, so I hope the strengthening will stop this.

Both upper and lower wishbones have been seam welded and plated where required. Steel strip has been welded around the ball joints mounting.

In the pictures you will see the suspension laid out on the floor. It shows the additional sump guard cross member, complete with spring skids that protect the inner wishbone mounts, and rose jointed tie rods that run from this cross member back to the lower wishbone. These are Abarth supplied parts from my original rally car. The tie rods add strength to the front wishbone/cross member, stopping any front rear movement of the wishbone, so reducing the stress on the inner lower wishbone mounts. This was then further developed into the Abarth modified lower wishbone and compression rod running rear to the chassis rail. Obviously the parts fitted to my car strengthen the suspension but do not improve the geometry, hence the later Abarth development.

The steering arms have been plated to add strength. The tie rod tubes now need strengthening, then the suspension can be fitted.



I have found a supplier of a clamp to allow conversion to drop link operation of the anti roll bar to wishbone mounting. I will look at this in more detail when the suspension is on.

The rear axle progress has been slow. All the strengthening has been done but the problem has been the brakes. I am fitting 256 diameter disc, as the works cars, but these were on the IRS rear end, not the live axle model. The problem is getting these discs and callipers into 13” wheels. Using Porsche 911 rear callipers, they just fit in. However, you then don’t have a mechanical handbrake. Trying to fit a mechanical hand brake has been problematic. Also it has to be approved by the MSA. I don’t think this is a problem, as I am using the Wilwood spot handbrake calliper. Only problem is making a bracket to hold it. Hopefully in a week or so this should be complete. At one stage I had designed a system to use the Porsche brakes and a modified original rear brake calliper as the hand brake. However after an hour or so with hardboard templates etc, I thought I had it cracked , but then realised the other side of the axle has the panhard rod mounting in the way so I had to start again.

As a note the original works cars with live rear axle used 3 pot calipers back and front. ( I think from a Fiat 2300) . The rear calipers were fitted at the top of the disc. They apear to have a seperate handbrake attachment on the caliper ( like the rear Dunlop Disc brakes of the 60's)

My original Rally Spider had front callipers fitted to the rerar of the car (and only a hydraulisc hand brake. ) This worked well with a balance bar and twin master cyclinders, but the brakes were a litle marginal and were always very hot.

The brakes will be mounted on a 10mm thick aluminium back plate fitted to the axle on the original calliper mount bracket, with additional mounting points. I will post photos when it is done.

The LSD has arrived from Russia via Germany. I have not had a good look at it yet but it looks well made. I will have a look inside before I fit it so I can get some measurements etc and look at the clutch settings.

Hopefully with all the suspension finished, progress will be a bit quicker.
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