K series ??? CRB- Update

[Rob Board]

Hi Gents, Further to my post last week about the possible demise of my CRB on my 2 month old x-power, I regret to say that my belief that it was just the fingers on the pressure plate bedding in, seem to be unfounded. Today on the way to work much wailing and non selection of gears. Bu**er! On pumping the clutch pedal disappears. Anyway as promised on my last post I would try and get to the bottom of it. I beleive John Vine is also making enquires. Phoned Caterham today, as it is a warranty job, but on discussion with Zoe @ aftersales, she is unaware of any problem. If the failures are as common as blatchat would lead me to beleive, then there is an inherent problem somewhere? The reason that Caterham are, I beleive, not aware of a problem is that they do not have many go under warranty. Given that most sevens maybe do not do that many miles in a year, means that failure, although in our eyes is premature, is not brought to Caterhams attention due to the one year warranty??? Due to this I do feel Caterham cannot be slated for something they have no/little knowledge of.

What I would be most grateful for is all you good peoples details of how, and when regards to miles/age your CRB's have failed. To put it in perspective, my syptoms started at 800 miles/1 month. Now 2 months old and 2.2K and a LOT worse.If this does indeed show a pattern of premature wear, armed with the facts Caterham have assured me they will investigate, which can only be of help. As an engineer I am most keen to try and get to the bottom of the snag, and as a novice sevener pass on something of use to others.

If the fault is really not that common I do appologise, but I await all your posts so I can collate all the facts B4 mine is changed. I have asked Caterham to keep the offending bits for inspection which they have agreed. Awaiting your tales of woe Rob.

 

[Dave_H]

Hi Rob,

 

I fitted mine in the middle of June and I’ve covered about 4000 miles since. It has been playing up for a couple of months though! But, as I said before, it’s only noticeable when it gets really hot.

 

Dave

 

[Andy Best]

Rob,

 

I too would like to investigate this problem, for the record my car has only done 12000 miles and the CRB has failed and damaged the clutch cover fingers as a result in hind sight I should have investigated when the noises etc were first noticed at 6000 miles/4years old.

 

The car has covered 6000 miles this year and the clutch problems went from just a noise to virtually unusable in the last 1000 miles.

 

I believe I have been running the car for some time with a collapsed CRB to depress the clutch, it looks like the plastic? backing part of the CRB is the bit that fails possibly by breaking free fron the bearing part.

 

I am currently investigating the replacement options and will follow this thread with interest.

 

As you say most of our cars are out of warranty when the fault is discovered and we sort the problem without ref to Caterham due to cost/inconvience of travelling to thier workshop.

 

If caterham would like to view the CRB (whats left of it) I can post it to them!

 

Andy

[Nick Green]

My car's CRB started making noises last year, after about 2 years and 9k miles. I changed it before it fell to bits properly. My 6-speed box already has the steel sleeve fitted to it.

 

I rang up the suppliers of the bearings to Caterham and asked them about alternatives. I was told the bearing supplied to Caterham goes in Cortinas, Sierras, Granadas, TVRs... I asked about bearings with metal back plates and was told they hadn't seen any for years. This has been confirmed by other people in the trade I talk to.

 

Given the cars the bearings are normally fitted to, I don't see why they should fail in 7s.

 

However, Caterham do like to fit a spring to pull the clutch pedal down. Or rather, I think its purpose is to keep the clutch cable under tension, to prevent it dislodging from the clutch fork or from the hole in the front of the pedal box.

 

My theory (and I must stress it is only a theory; I haven't done enough miles to confirm it yet and it doesn't explain why some CRBs last <1k miles) is that this spring is the cause of the problem. It gives a similar effect to driving along with your foot resting on the clutch pedal ie "riding the clutch". The bearing is not designed to turn every revolution the crankshaft does over a long period of time.

 

While there are clutches out there known as "zero clearance" clutches, which are designed so that the CRB is in constant contact with the finger things, I am led to believe these bearings are rather more substantial than the type Caterham use.

 

The "fix" I have put in, may only work on the Caterham dry sump setup. I have removed the spring, and arranged the nuts at the pedal box end of the cable sleeve, so that they are either side of the bulkhead. This stops the sleeve from coming out of its hole. At the fork end, this is already tight enough on my car, so that the nipple on that end of the clutch cable doesn't slip out. With the split pin above, and a cable tie cunningly arranged to stop the nipple dropping down should it pop out anyway, I've done a year like that. When my foot is not on the clutch pedal, the CRB is now free to drop away from the clutch fingers. I can also put my foot under the pedal and lift it slightly, to be really sure.

 

Haven't got up to 10k miles yet though... If the bearing in there now starts rumbling before then, it's back to the drawing board.

 

Thinking about it some more, of course what I've done isn't so different from adding a spring to oppose the one Caterham fit. And someone has already tried this... Whatever, it has to be better than constant contact.

 

Edited by - Nick green on 10 Dec 2002 11:28:15

[Steve-B]

nick,

 

would you be so kind as to take a picture or two of your solution so we could have a look at it. if you don't have a website, send me an email and i'll post them on mine.

 

i've wondered about the spring, as our old cerbera didn't have one. nor has any other car we've ever owned.

 

interesting theory to followup on!

 

Steve

Metalic Black SV-VHPD

click here to see our 7 and rallye pictures....

[Nick Green]

Steve, I can certainly take some pics, but it might take a day or two to get them to you or on the web.

[John Vine]

Rob,

 

For Simon Lambert's response, see here.

 

(For those of you that haven't heard of Simon, he's the Aftersales Manager at the Caterham factory.)

 

For info, my 1999 1.8SS CRB has failed twice, once at 18K miles (catastrophic disintegration, accompanied by horrible metallic scraping sounds) and again at 25K miles (only gentle squealing so far, but not promising!).

 

JV

[Rob Walker]

Simon Lambert was certainly aware of the problem when I had my bearing fail about 18 months ago.