420R (S3) Radiator design issue, regular failures???

[CtrMint]

Final result., loads of clearance now.  Car is currently cooling in the garage, ran out of time before tea, assuming its all good but will check for leaks later.

I also used a small OD rubber washer and nylon washer between the bobbin and hanger just to try and suppress (reduce) any vibration.

It was a bit of a pig to get central on the bobbins, but eventually got there.

[7 wonders of the world]

Nice one Mark, the washer you mentioned, this has should have increased clearence between the rad and button head too..?

If you have some to hand, use a thin plain washer (form B)  under the nyloc securing the two brackets, spring washers are best put in a box and weighed in for scrap. the nyloc needs no assistance - not that they offer any !

[CtrMint]

Cheers Neil.

I didn't want to over tighten the hanger to chassis nut as I wanted the rubber washer id inserted between to at least have some chance of helping reduce vibration, so thought a spring washer plus the nyloc was a safe bet.

 

 

[ScottR400D]

So did CC send you another rad? Sorry if I missed that post! 

[Geoff Brown]

Good fix. You need to add step by step instructions with pics to Guides - Maintenance. This addition will assist others who will come across the problem.

Also submit to CC for a workshop notice ? No that is a silly idea as they could not have an owner bettering them when it comes to practical design & innovation ?!

[CtrMint]

Might be a good idea, but I'm slightly suspicious I haven't solved the fatigue issue completely.

I noticed this evening there is still a significant amount of vibration being absorb by the rad, not from the chassis mounts, but the large diameter stiff hose at the top.  Holding that you can feel most of the vibration at tick over in that hose, rather than the chassis.  I'm wondering whether I should try and swap to a silicon hose, maybe cut the stiff hose and use an insert to extend into a silicon hose, which might suppress more of the vibrations.

[Jonathan Kay]

Can you add some photos of that hose and area, please.

Jonathan

[CtrMint]

 

this large one

[timb2117]

Sorry I am a bit neanderthal, but from my viewing of the OP photo, it needs;

1. The right angle bracket which is welded onto the chassis cutting approx 5mm back from the right angle bend.

2 . This tab inverting and welding back on to the same spot.

Result no rad movement up or down, the bobbin is doing its job, no clearance issue for pipe inlet.

[Jonathan Kay]

Tim:

I think that the alterations that you are suggesting have already been done, although by bolting rather than welding. 

Jonathan

[Jonathan Kay]

"I noticed this evening there is still a significant amount of vibration being absorb by the rad, not from the chassis mounts, but the large diameter stiff hose at the top.  Holding that you can feel most of the vibration at tick over in that hose, rather than the chassis.  I'm wondering whether I should try and swap to a silicon hose, maybe cut the stiff hose and use an insert to extend into a silicon hose, which might suppress more of the vibrations."

Thanks for the photo.

Is that long fat hose ordinary black rubber throughout? 

If you remove one end does the other end sit nicely for length: so that it isn't compressed when connected at both ends?

Is the smaller hose running across it at the bend bearing on it?

Jonathan

PS: I've looked at the usual suppliers of silicone hoses for something like a bellows section but not found anything yet.

[timb2117]

Sorry Jonathan it just looked from the photos in the OP that the upturned bracket was touching the inlet pipe and the bolt head was within 1mm of the rad tank, negating the bobbins action. Whereas the photo you have just above shows same alteration bracket clearly missing both areas and the bobbin can work well.

Anyway hes getting you on the case so that will see it solved :)

Best regards Tim.

[CtrMint]

HI Jonathan, 

Thanks for the support. 

"Is that long fat hose ordinary black rubber throughout?"

Yes it's a stiff thick walled rubber hose all the way to the back of the engine near the submarine.  It's surprisingly hard for a coolant hose.

"If you remove one end does the other end sit nicely for length: so that it isn't compressed when connected at both ends?"

I'd say no, there is some additional length present, around 2cm of excess, so a little tricky to trim.  Making it too short might cause the hose to get dangerously close the belt too.  I can see your thinking, but given the stiffness of the wall I'm very doubtful reducing the length would render that much of an improvement.

"Is the smaller hose running across it at the bend bearing on it?"

Yes but and I know it's not scientific but from touch there doesn't appear to be any noticeable vibration coming from that hose.

I've found this sort of hose'

https://www.carbuilder.com/uk/28mm-id-x-225mm-long-vulcoflex-flexible-coolant-hose

There's also a number of options from Viper

https://www.viperperformance.co.uk

https://www.viperperformance.co.uk/silicone-hoses_10226_ultra-flex-hose-750mm-long.html

I'm not sure if my modification to the bracket is the fix, even if it is, I can't believe the level of vibration is good for the rad, so making an improvement here, has to be beneficial.

[David aka Blue7]

The existing hose seems to be very close to the bonnet, but the Car Builder hose should certainly reduce vibration.  What puzzles me is why other 420R owners aren't having similar problems, or maybe they are?

[CtrMint]

Based on PMs I received over Instagram when I posted about the rad failure others are experiencing similar problems.  

Also there's the ongoing discussion about the radiator quality, maybe the rads are better than thought and a contributing factor is the hose.  It's overly stiff and doesn't naturally fall into the required position.  It's design to meet the radiator further in the middle, hence why it appears to sit close to the bonnet.

Of course I might be chasing something that doesn't exist.  Having had a couple of issues, which CC put down to bad luck I'm trying to minimize any potential.

At the moment I'm thinking about cutting the hose under the plenum, adding an insert and then running a flexi hose to the radiator.

[John Vine]

...and a contributing factor is the hose.  It's overly stiff and doesn't naturally fall into the required position.  It's design to meet the radiator further in the middle...

I think that is exactly the problem.  Your top hose is designed for the earlier rad, and that enforced extra bend means the hose is under permanent tension.  This is the original design:

 

The hose is made of EPDM rubber, very tough but not very flexible.

Of course, the proper solution is for CC to offer a hose tailor-made for the new-style rad.  I'm a bit surprised that they haven't done that already.

JV

[CtrMint]

It would be much better if a hose capable of supporting the new design rad was available.  As far as I'm aware it isn't.

Viper offer a service tooling and manufacturing bespoke hoses.  I wonder how many it would take for that to be affordable.  Possible group buy? Maybe CC could adopt the solution too. 

[7Up]

this could get popular!

[ChrisC]

You do know CC have changed the top hose to be more flexible by reducing the wall thickness?  Found that out late 2019 early 2020, since then all the hoses have been changed.  The new hoses have a different finish and use the new logo. 
 

[Jonathan Kay]

"I'd say no, there is some additional length present, around 2cm of excess, so a little tricky to trim.  Making it too short might cause the hose to get dangerously close the belt too.  I can see your thinking, but given the stiffness of the wall I'm very doubtful reducing the length would render that much of an improvement."

...

"Your top hose is designed for the earlier rad, and that enforced extra bend means the hose is under permanent tension."

...

ChrisC:

"You do know CC have changed the top hose to be more flexible by reducing the wall thickness?  Found that out late 2019 early 2020, since then all the hoses have been changed.  The new hoses have a different finish and use the new logo."

...

From the first two of those I was going to recommend cutting the hose so that it was relaxed, and if that didn't decrease the vibration then fitting a length of that axially compressible hose somewhere in the run.

But ChrisC's observation offers an alternative solution.

Jonathan

[ScottR400D]

Did they change the shape of the hose too? Surely the proper solution would be to design a hose to fit properly, not to do the usual CC thing of changing something that's not really the problem in an effort to make the outcome slightly less worse. 

A softer hose could still put a stress on the assembly if it's forced into place. 

[CtrMint]

Chris can you post a pic if you have the revised hose.

If the material has changed I shall raise that with CC and push for a discount on a new hose.

Also how did you find out the hose has change, the shape appears the same on the parts site.

The more I've thought about this, if CC revised the wall thickness, it might have negated the need for me to modify my mount!  I did run my intentions via CC, including why, you'd think they'd just say we've increased the clearance with a new wall thickness.  Sometimes I do wonder...  Rather frustrating start to my Sunday. 

thanks

Edit, (again).  I've been and checked my picklist. it's the same ref as that used for the current hose.  Normally when CC revise a component there's a increment in the last char, usually a letter.  Well that's the approach with the radiator.

[ChrisC]

I found out because I cut my top hose to short during my build.  I just ordered a replacement.  The shape hasn't changed, but I suspect that's because 360 cars are still using the older design rads (or should I say the last one I saw, an early 2021 kit was).  According to images in v2 Duratec build manuals they should have the same rad without the oil cooler, not that those images are anything to go by.

These cars are constantly changing, as suppliers come and go, expecting things to remain the same is just unrealistic. CC just doesn't have that sort of buying power. 
 

Side by side photos of the new hose are https://caterham420detailedbuildblog.co.uk/2020/01/30/engine-plumbing-electrics-part-2/

 

[CtrMint]

Thanks Chris

"These cars are constantly changing, as suppliers come and go, expecting things to remain the same is just unrealistic. CC just doesn't have that sort of buying power."

I appreciate that.  I don't believe they randomly change specs of a part just because of a change in supplier.  I'm sure there is some part validation.   I guess we won't know for sure whether the reduction in diameter was an action designed to better accommodate both rad layouts with one hose or just random.  Either way, I'm sure it could have been suggested before I modified my car, but more notably before CC shelled out for a complete rad and cooler under warranty. 

[ChrisC]

I did mention the slimmer more flexible hose in post #20 back in August.