Docking Radiators Have you had a Failure?

We have supplied many docking radiators and we also fit them to the southerngt if these rads are mounted correctly and you do not have a badly flexing frame that they are mounted to there should not be a problem i agree with the post above if you keep splitting rads you have other issues.
If people have had one fail, had it replaced, and the new one fail too, then I would suggest that that pointed to the radiator mounting rather than the radiator itself, as I personally have only found them to be very good, and phenomenal at cooling.
If what you say is correct, I should be suffering from phenominal chassis flex and my Pro Alloy radiator, which is bolted solidly to the chassis, should be leaking after a season's use. It isn't.
No, the problem lies in Docking's welds between the core tubes and the plates which make up the ends of the collector tanks each side of the radiator. I had my first failure within days of first fitting; this was a radiator, not a mounting, problem.
With the second rad, I mounted it on flexible rubber bushes at the top, but left the lower mounts out, so it was restrained at the bottom only by the hoses. This eliminated the possibility of chassis twist being a cause. The rad still failed.
I agree, Mel Johnson at Docking is helpfulness personified, but I'm afraid I got sick of little puddles of coolant and went for something more fit-and-forget.
If you're receiving good service from your Docking, I wish you well, but listen to the rest of us clamouring about leaks!


Lifetime Supporter
I'm with Steve B, Dave, Glenn and Mick on this.

If the front cradle is insufficiently trussed and stiff enough, then why consider using a lightweight thin wall alloy radiator with a fill weight of about thirty pounds as structural member to pull in your top rails - with M8 bolts acting against an alloy fillet weld ?
By this you discount expansion > contraction, vibration and shear.

Have a look at an original and see that there is plenty of steel around the front end framing the radiator and also supporting a jacking bar. These cars use rubber damper pads.

Fitting heavy radiators without adequate anti-vibration / shear dampers against the suppliers recommendation is asking for trouble, whether it be Serck Marston, Pro Alloy or Docking.

Shear Mounts

My Euro's worth.

Brian Magee

This is the only picture I could find that shows how my radiator is mounted as it now has ducting around it. The radiator has posts welded to the top and bottom which fit into the Ford Fiesta radiator mounting grommets. The picture shows the original copper radiator but I now have a Docking fitted. There has been a slight weep in one place, more an antifreeze stain.



Responce from Docking Engineering


First of all my thanks for allowing me to respond to the comments posted on the forum about our products which we have been supplying to GT40 owners for well over 12 years. From the level of our sales I know that the vast majority of our customers are happy with the service, performance and reliability of our products.

Unfortunatly for us as soon as the radiator leaves our factory we have no control over its instalation in the car or its future use. If our radiator or any radiator is fitted in such a way that it forms part of the forward structure of the car and is subjected to twisting loads it will fail. The water vains in the cooler have a wall thickness of 0.48mm and they are already subjected to water pressure and thermal loads, the last thing they need is flexing, vibration or shock loads from the chassis.

If you mount the radiator between two points that move independently it is just a mechanical fuse and it will fail through fatigue. In Tony Hunts case he has fitted a thicker radiator, this will have a greater cross sectional area and it may well delay the fatigue process but if the twisting loads are still there it will eventually fail, it is still a mechanical fuse its just a higher rating.

The advice for mounting our radiator or in fact any radiator is isolate it from any structural, viaration or shock loads. If you lift the bonnet of your road cars you will often see that the radiator is only located by two pins in crommets at the bottom and a pair of U clamps at the top, its almost free to move around and expand, it is certainly not part of the structure.

If you have had problems with one of our products I can only appologise, when problems have occured we have tried to be as helpful as possible. We take great pride in our products and service and if there is a legitimate claim within the warranty period it will be dealt with in a professional manner.

We have been producing radiators for motorsport and special vehicle use since 1983 and we know what and what not to do, if you need adivice on mounting your radiators please feel free to give me a call. With 34 years experience in the motorsport industry it may just be that I know a little more about mounting coolers than some of your fellow members or those wishing to promote their own products.

Kind Regards Mel Johnson
Docking Engineering

Mike Pass

I am pleased that some people are happy with their radiators. However my Docking radiator is mounted on very soft and flexible mountings and still leaks.
Whilst Docking assert that they know how to do things, they imply that their customers do not. Perhaps if Docking supplied the "correct" mountings with their rads and comprehensive info on how to ensure that there will be no issues then that may go some way towards ensuring 100% happy customers which is not currently the case. Possibly their rads are more delicate than some others and need a softer bed to sit in. If this is the case then a lot more customer advice is needed than "if you have a problem give us a call."
I have also not heard of other makes having these problems. These items are quite expensive and not something that one would expect to replace for a very long time.
I am trying to be positive whilst still l,ooking at finding £400 for a better leak free rad.

I do not really want to participate in an endless debate on the subject but I do feel that I should respond to some of the comments made by Mike Pass.

In an ideal world we would supply a complete fitting kit for the radiators but there are simply to many chassis manufacturers to make this viable, add to this the level of cusomisation by builders and it makes it almost impossibe to produce a one kit fits all.

In every conversation i have had with a car builder I have always stressed the importance of soft mounting the radiator to prevent twisting and vibration. The simple fact is that it is not good engineering practice bolt or hard mount a radiator between to chassis points that move indepenently, I cannot understand how anyone can think that this is a good idea or more importantly why anyone would want to do it.

The radiators we produce are designed to provide high performance cooling and are built to the same standards as our other products. If you have had an identical problem from a second unit built one or two years later I think its fair to say that its an instlation problem, the law of averages would state that you just couldn't be that unlucky.

If anyone wants or needs advice on the installation of their radiator please do give me a call.

Kind regards Mel Johnson
Docking Engineering

Mike Pass

Thanks for your reply Mel. I appreciate that, unlike some vendors you are concerned that your products perform well. Whilst I understand the point that every install is different it does not negate the point that the inclusion of an installation advice sheet with each rad sold and to sell a soft rubber mounting would go a long way to avoiding these issues. After all the purchasers of your radiators will have to go through the same tedious process of sourcing something suitable. It may even be a profitable item for your company.
As I said before this is intended to be positive and may help to avoid issues for the many builders on this forum and the wider community.
Being concerned by this forum thread back in January, I had a look at mine and apparently it was also a Docking and ......... unfortunately leaking coolant.
The sticker on the radiator told me it was made in april 2010, not even a year old.
I contacted Mel Johnson of Docking in Silverstone and explained my problem. I e-mailed him pics of the mounting which was directly to the chassis. He told me the mounting was totally inappropriate, but as shown in the pics it was designed to be fitted like it was.
Mel offered me to fix it, so I send it to Silverstone.
I did some research and thinking how to get a better mounting, in rubbers this time. For this I needed a 3 cm clearance for the rubbers. I asked Mel to make the adjustments.
Finally he returned me a complete new radiator with the mounting adjustments as I required. The radiator and rubbers fitted right in.

I must say, great service; new radiator with custom adjustments as I requested.


FWIW, there's more than one way to skin the radiator mounting cat to ensure long life without leaks.

Although not yet blessed with a GT40 in my garage, I have a number of other cars including a Contemporary 427 Cobra replica with a Docking-like lightweight aluminum radiator. It uses a novel approach to remove stresses from chassis flex from the radiator itself.

The radiator has two tabs affixed to the side tanks, down low, which bolt to the underside of the main longitudinal chassis tubes. If the chassis twists (which I suspect it does, at least a bit), those forces would then cause the radiator to rotate about the longitudinal axis.

To securely mount the top of the radiator while isolating it from the chassis, this is the approach used:

Note that the arms are designed to let the top of the radiator swing side-to-side, while securing it in the fore-aft plane.

This radiator has now been going strong for going on 20 years with nary a drop of leakage. :thumbsup:

About Docking radiators--they seem to be made with some mystical properties, as they seem to cool better than same-size radiators from other manufacturers, based on my limited exposure to them in friend's cars of various types in the UK. That said, it's easy to get over-confident in them.

One of my friends is a lightness nut, the kind of guy who drills holes in everything in the name of weight savings. I've been hard-pressed to keep him from trying to put lightening holes in his tires! :laugh:

He had a Docking radiator custom-made for his Pantera; I don't know if it's smaller than their standard Pantera offering, but it's absolutely tiny, less than half the thickness of the (perfectly good, heavy, brass) radiator that came out, and a fraction of the weight.

Running down the motorway on a damp, dreary English morning, it keeps the car nice and cool. However, stuck in traffic on a hot day in Le Mans or Modena, the temperature rockets up to right on 260 degrees F and hovers there dangerously. I'm astonished his engine hasn't melted down completely; the fact that he has an aluminum block and heads may have helped his cause there.

The point being, don't get carried away with the wonderfulness of Docking radiators such that you engineer a sub-optimal design in the name of weight or cost savings. I suspect the Docking boys know a hell of a lot, and would encourage people to follow their advice, and if anything, err on the side of caution when having a radiator custom-made....
Just found that my set up, completely hanging the radiator in rubber bushes, did not hold.
After quite some investigation for my slowly lowering coolant levels, I finally found out that the radiator is wheeping from both sides. :-(

Any tips or advice here will be welcome!

Mike Pass

Hi Doc,

The best thing to do I think would be to take some clear pics of your radiator install and contact Docking to see what they say about the issues you are having with your radiator in relation to your install.
Maybe put the pics on here so people have see how it is installed on your car.



I have had a docking in my car over 10 years now with no leaks at all although haven't used the car much in the last 4 years or so.