Docking Radiators Have you had a Failure?

Ian Anderson

Lifetime Supporter
I just readon a thread of another Docking radiator springing a leak

Now I know of a fair few UK GT40s that have had dockings that have started leaking and probably had them changed ------ for another Docking

Reading betweem the lines I would think that perhaps we should have a claim on Docking for producing radiators that are not up to the mark.

But actually how many of their radiators have failed?

I'll start I had a Docking after 2 years it started weeping - even dripped at 1st MOT (3years after SVA) I ran it for 1 more year with ever increasing "rad weld" before changing it out this year for a Frank Catt special

Please post below on your failures - only Docking radiators

also advise if you have changed make after the failure


Andy Sheldon

Tornado Sports Cars
GT40s Sponsor
I know of several customers who have had Dockings Radiators fail. They have been replaced with our Radiators.


my only failure with my Docking is that its been sitting in the car too long not being used!!

I think I may need to change the mounts looking at the recent posts, and maybe get some gussets welded on!


Brian Magee


As you have started this post will you be informing Dockings to give them a chance to reply?
I have had a Docking for about 3 years with no serious problems.

My original GTD radiator failed in Autumn 2006, so I bought a Docking, which Brian Magee put in for me that winter.
At the end of the summer 2007 it was leaking badly from where the core tubes enter the headers at each side of the radiator. I took it back to Docking, who said it was irrepairable and replaced it.
By 2009, this radiator was also leaking from the same places, so I took it back to Docking, who sucked the air out and sucked silicone sealer through the leaks. This lasted about 6 months.
By this time, my confidence in Docking had evaporated and I replaced it with a Pro Alloy GT40 radiator, which was about 1" thicker than the Docking and caused all sorts of havoc with the aircon evaporator mounting.
Initially, the Docking was mounted on 4 rubber grommets with tube inserts, but the grommets quickly cut through with the vibration. The Pro Alloy is directly bolted to the chassis and is bone dry (touch wood).
After my experiences I wouldn't recommend a Docking GT40 radiator to anyone.

Ian Anderson

Lifetime Supporter

As you have started this post will you be informing Dockings to give them a chance to reply?
I have had a Docking for about 3 years with no serious problems.


Hi Brian

I believe it is only fair to do so
I will advise them of theis thread and invite their comments

Had a failure. Had a small fight to get it sorted. Failed again. Small fight and sorted. The car now belongs to Mike P and is leaking again. Put one in my new car and mounted it on 6 rubber mounts to isolate it as best I could from the chassis. No problems up to now, touch wood.
My failure was to mount the rad in mounts that were not soft enough!

Although I had changed from rigid mounting to rubber grommets and top-hat bushes it was still too rigidly mounted. Ali will work harden and become brittle if allowed to flex or vibrate whilst under loading. I regret not originally having Docking's advice:- that I must 'ensure the rad is soft mounted'.

My replacement now rests on a foam tape bed and has the lightest rubber isolators I could find. The rad will now move quite easily in every direction before the mounts firm up, if there is not this degree of compliance it is probably too rigidly mounted and stress the rad core.

I think any ali rad will eventually fail if it is rigidly mounted and is subjected to flex and vibration. Traditional copper rads are not as susceptible. IMHO.


Ron Earp

I think it is important to soft mount them.

That said, my Z race car has a solidly mounted aluminum radiator, just bolted to the frame, and it has been in the car since 1992. I think the construction of the radiator plays a role here too.
The need for soft mounting depends on the stability of the aperture the rad is to fit into.
The problem is that most replicas have a 1" tube frame at each side that though welded at the bottom to the main chassis, is open at the top. My car also has the MkII bobbins on the outside of the frame to carry the front clip.
This 'U' frame has no diagonals or other stabilisation to prevent flex. A rad rigidly fixed in the opening becomes the diagonal bracing, this will eventually work harden the ali, the stress focus is greatest where the core meets the header-tanks. My rad had stress cracks in all four corners of the core.
To get a soft pliable mounting I used these rubber insulators from RS Components
FIBET | Mechanical Components | Anti-Vibration Mounts and Feet | Anti Vibration Mounts, Male and Female Threaded | Cylindrical Mounts |1008VV10-45

The Docking unit has been very efficient and I have never had any hint of overheating ,even in heavy traffic and hot weather ( LM Classic 2010)

So if you put a brace across the top this would help?

I have some of your original mounts you sent me. I assume I will need to change them then?

Hi Brett,

With hindsight I think I would change to the lightest soft fix you can devise that will still hold the rad in place and allow the rad to flex it's mountings not the rad itself. I'm sorry the mounts I made have not performed better. There are some pictures on my build log of the new method
I think a top brace may help to stiffen the 'U' frame if it could be suitably gusseted, not a practical solution as it would probably compromise the rad or front clip clearance.
I did consider fitting diagonal bracing from the top of the radiator mount to the opposite lower main chassis frame but the rad fans and bottom edge of the nostril panel interfered. So I went with the soft mounting.


Dave Bilyk

Dave Bilyk
my mounts are the same or very similar to Steves. They are the right way to go over stiffening the supporting structure as they are the only way to protect the rad from both stress AND shock. They also give the opportunity to isolate the rad electrically, thereby preventing corrosion due to stray currents etc.


Glenn M

I feel that I have to say a word in support of Dockings. They state categorically that the radiator must be correctly mounted and immune from any flex in the chassis. After all you can’t expect the radiator to become a structural part in preventing flex, and the chassis does flex at the front – some a lot more than others.

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. Indeed I frequently run with half of it blanked off as I have trouble getting everything up to temperature!

I would also say that in my experience they are an extremely helpful company and have certainly bent over backwards to help me out of a tight spot in the past.