bstark

You may not be so lucky, but I had a knocking sound that increased with road speed that was eventually traced to one of the centre caps of the alloy wheels...

Just took a bit of sealant to sort it. I was imagining all sorts of things so was delighted when it turned out to be something so simple. Fingers crossed you have the same luck!

Just reading your original question "is there a point to this?"

It depends what you are trying to achieve. Is it better drivability and real life performance on the road, or a noticeable increase in flat-out performance at the top end?

If the former you might want to look at 3D mapped ignition if you haven't already fitted it as a starting point. It transforms the torque and drivability off a Supersprint spec xflow, 

If you don't get any joy they are quite economic to get laser cut from .7mm stainless steel provided you are able to make the cad templates yourself.

I had to do this recently as mine is from a year when Caterham tried a different size which you can no longer buy. Total cost was about £100 plus my time, having sourced the steel offcut online. 

I normally use HG Sticker Remover, pretty sure it is petroleum based but anyway it works really well

I have the same ATB and Jigsaw CWP setup in mine from my sprinting days. Also had the axle baffled and the half shafts crack tested at the same time.

Good job I did as one was cracked and needed a NOS replacement.

Not trying to replace with LED, just replace a bulb (hopefully).

@Paul - that's what I'm hoping but like 7_malc I've had experience of the switchgear getting brittle with age so don't want to just yank it out without checking first

This is the old style dash with the three warning lights mounted in a vertical row between the speedo and rev counter. 
 
Do they just pull out, or twist first, or do you need to unscrew from the back? I can't make it out due to the steering column and other gauges being in the way and don't want to start ripping things out to find they just pop out the front  

Just adding this in case it helps someone in the future.

You can tell whether you have a 110 tooth or 135 tooth flywheel on your xflow by measuring the diameter of the starter pinion.

135t flywheel = 26.5mm diameter pinion

110t flywheel = 29mm diameter pinion

Quicker than counting teeth!

Just to add an element of confusion, the Hitachi WOSP starter has a 27.4mm pinion offset to suit. That threw me initially but is asterisked in the website to explain.

Anyway, works a treat and spins a lot faster than the original

Thanks both 

I was hoping to avoid having to do exactly this! 

Hi all,

I'm thinking about replacing the starter on my 1700 4 speed xflow with a modern high torque unit. Looking at sites like Powerlite they warn that a lightened flywheel means the standard Ford unit may not fit (presumably different ring gear?).

Were Caterham consistent in their flywheel spec? And what's the correct starter to go for?

The engine was upgraded to a Steve Parker Racing unit before I bought it (was originally a 1600 Sprint) but they clearly kept the original 4 speed Escort Sport box so assume kept the Sprint flywheel.

 Thanks,

 Bob 

A-ha - found it - thanks!

I'd been pointed towards the wrong end of engine so hadn't taken the nosecone off, and was looking for something much smaller.

Cheers,

Bob

Can someone point me in the right direction as to where on the engine I can find the oil pressure switch / sender? It's a vdo unit if that makes any difference.

Can't find the bugger anywhere so guessing it's hidden under the carbs?

Bob

If you've got the time then fitting a Megajolt 3D ignition to it will help the tractability at lower revs no end.

Made a startling difference to mine, and that is on a 234 cam. FWIW I'm getting 138bhp at 6000rpm according to the rolling road I use, and it was effective enough when I used to sprint it. It's a Steve Parker Racing unit rather than a Caterham one.

Bob

Car runs fine, it's purely a charging issue.

Thanks SM25T - car is booked in with a supposed 'top notch' auto electrician next week (via a mechanic who we have known for years - Jon ex-of 7 Indulgence) so it's now an SEP

Thanks everyone for your suggestions. I'll report back on what the chap finds. Hopefully it will be easy, cheap, and not embarrassingly obvious!

Bob

This is maddening!

Stripped the dynamo and the springs and brushed indeed look fine. Fitted the new set of both just in case, and also cleaned up the brush runners as one of them was full of slight surface rust.

Put the dynamo back together, checked it motored ok (it did) and reinstalled in car.

Exactly the same symptoms, only now the light stays on once the increase in revs has set it off, even if you then back down to idle. It did exactly this the last time the dynamo was stripped by the specialist.

So, individually everything checks out to the level I can apply.

Auto electrician here we come, if I can find one who gets these...

Have just checked regulator earth - fine, all the wiring between regulator and dynamo - fine, and all the fuses - fine...

Well, checked, cleaned and where needed replaced all the contacts to the dynamo and the earth strap. Several were pretty ropey and the earth strap contact was really poor.

Put it all back together and... No change...

Check the voltage at the battery and it rises to about 15.4v and then drops straight back as the red light comes on with revs. Same story if you take the voltage from the brush terminal on the dynamo but with a higher voltage. This was all in the garage so no real movement to confuse things.

So it all points in my mind to the dynamo itself (despite assurance from the local specialist that all is good) and it is the brushes floating as the rotational speed increases.

Grrr...

Funnily enough someone on Pistonheads has just suggested the earth strap.

This one may have legs as I can imagine a situation with this that matches all the symptoms.

The engine mounting on the 500 is very soft and positioned centrally at the back, allowing a lot of torsional movement of the engine under load.

The earth strap goes from underneath the dynamo mounting on the far left of the engine (middle of cooling fan) to the far left of the engine bay (one of the rear panel mounting bolts). If engine movement under load is pulling the strap and breaking the connection that would explain the repeatability under load, and why it could be initially fine at high revs but no load in the garage after refitting the dynamo. The problem first showed itself under high load cornering hard which would also fit.

Heading to garage as soon as I get home to check!

Bob

Elie - that's kind of what I've been wondering about. It's a pain to pull the dynamo on these so didn't want to speculatively pull it out yet again if there could be an easier wiring issue elsewhere. I'm guessing the brush springs losing strength could have a similar affect?

Jonathan - I think it is heat related, but we are only talking long enough for it to have warmed up a little (couple of minutes running time from stone cold) for the effect to happen. No rev counter so guessing at engine speed (easier to do in top gear).

The initial problem was certainly being seen at the battery end where the voltage would climb to just over 15V then immediately fall off to 12.3V or so at the same time the light came on as you slowly built the revs.

That's an interesting thought...

The pulley is held on by three triangulated bolts rather than a central bolt so unless something is loose inside (which I'd have hoped the dynamo expert would have picked up on) I can't see how it could.

Just to make absolutely sure I've just tried tightening the fan belt to the point of over-tight and it's actually made the problem worse.

In garage, light went out, as soon as I drove forwards the light went on, and then stayed on even at idle.