Myles Posted October 30, 2005 Share Posted October 30, 2005 OK, We took the engine and box out today so that the chassis can go to Arch. The engine has been in since March and has covered no more than about 5k if that. The CRB was new at the time and was one of the SKF froggy-jobbies. I'd not experienced any problems with the CRB (no noise etc.) - but when I slid it from the input shaft, the s*dding thing turned out to be in two pieces! The metallic front bearing section had popped off the plastic carrier section. In use, this probably didn't mean much (the two halves were probably held together OK) - but wtf!?! PIle of poo or what??? Project Scope-Creep is live... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Bricol Posted October 30, 2005 Share Posted October 30, 2005 Mine doesn't even clip together as new. In operation all the carrier has to do is stop the rear of the race turning - and as it always under a preload force, it won't come apart in use . . . Bri Link to comment Share on other sites More sharing options...
Myles Posted October 30, 2005 Author Share Posted October 30, 2005 Mmm. It doesn't fill me with confidence. I'll put a new one back in, obviously... Project Scope-Creep is live... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
The Polisher Posted October 30, 2005 Share Posted October 30, 2005 Hi Myles, Pleased to hear that the engine came out with no problems! Did you increase the preload as discussed in recent threads? I changed the spring anchor point soon after my build and have done 17.000 miles since with no problems. Good time to find the problem.........better than engine out for the sake of £12 !] Good luck with the refurb! Dave H. Mad about S77ENS Link to comment Share on other sites More sharing options...
Myles Posted October 31, 2005 Author Share Posted October 31, 2005 Dave, Nope, I didn't increase the preload beyond what was there already. I know I don't like this kind of reasoning where it comes to sump-foam , but the car did 22k on the original (non-SKF) CRB without any problems. The bearing itself is (probably - I didn't check it too closely) perfectly OK - it's just that the cr@ppy froggy construction resulted in the bearing parting company from the body. Unfortunately, I left it with the gearbox in V7SLR's garage, so I can't take any pics... The strip-down went fine - I'll be phoning Bruce and CC Midlands later this morning to arrange the visit to its birthplace... Project Scope-Creep is live... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Rob Walker Posted October 31, 2005 Share Posted October 31, 2005 IMO the preload has little if anything to do with CRB failure. Failure is due to the fingures tips of the clutch cover that contact the crb not rotating inline with the crank. I have seen several clutch covers with the fingure tips running out 10mm whilst having the engine spun during balancing, the tips then scuff away at the CRB face generate loads of heat and the grease is flung out also the bearing is constantly trying to self center. Combine this with track use gear changes at 7000 plus they don`t last long. If it was purely down to pre load every K`d caterham would eat CRB`s and they don`t. The new SKF bearing is two parts pushed together and separates easily, I would not describe this as a failure. Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted October 31, 2005 Share Posted October 31, 2005 I ride the clutch alot during road driving (a bad habit) and (touch wood) I've not had a CRB fail. I also have a very heavily sprung clutch so the CRB works hard when used. I'd agree with Rob, preload doesn't seem to be what causes them to fail from my limited experience. _________ / __ __ / ___ _//__T/__/_ ___ / (_) (_)/ / /`-'/o/ _______ /o/`-'/ / /// ( VDU7X ) // / /___/--_________/--/___/ Link to comment Share on other sites More sharing options...
anon7 Posted October 31, 2005 Share Posted October 31, 2005 Hi all, Recently put new clutch and CRB in my 7 (1.8 K) and now have what can only be described as an occasional "twittering" from the car. This appears to be coming from the clutch sort of area and happens when the clutch is engaged ie: pedal up. This happens when driving along or when at idle. I have thoughts that it must require some sort of adjustment or Pre-loading as it seems to stop with a light pressure on the clutch pedal. Any thoughts please? Thanks Shaggers In space no one can hear you scream.....In a seven no one can smell your bottom ! It`s not yours,it`s............. R7 NOW well actually MINE now!! Link to comment Share on other sites More sharing options...
Myles Posted October 31, 2005 Author Share Posted October 31, 2005 Shaggers - that's the normal layshaft rattle. TADTS and nothing to worry about... ...except that I've never heard it on the move... When hot, in idle, at a junction - yes (TADTS) - but on the move??? The general rule-of-thumb seems to be: i) Noise when depressing the clutch = CRB ii) Noise when releasing clutch = layshaft. Project Scope-Creep is live... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Normans_Ghost Posted October 31, 2005 Share Posted October 31, 2005 I would say that CRB failure is caused by NO pre-load. Imagine what's happening to a bearing with no pre-load. It's going from 0 to 4000 rpm (or more!) almost instantly. Pre-load keeps the bearing turning all the time but with little load. Norman Verona, 1989 BDR 220bhp, Reg: B16BDR, Mem No 2166, the full story here You and your seven to The French Blatting Company Limited Link to comment Share on other sites More sharing options...
The Polisher Posted October 31, 2005 Share Posted October 31, 2005 Brian, I know people have differing opinions about pre load but as Norman says you have to have sufficient to keep the bearing revolving all the time. A friends new Roadsport recently made the type of noise you describe and I cured it by shortening the clutch return spring and connecting it to the clevis pin instead of the drilled hole in the arm. Done in 5mins. Dave H. Mad about S77ENS Link to comment Share on other sites More sharing options...
anon7 Posted October 31, 2005 Share Posted October 31, 2005 Thanks Dave I'll give that a go. Sound doesn't sound like layshaft (which I also have ) more of a high pitched bird singing twitter if that makes sense. I'll check the cable adjustment etc tomorrow. Shaggers In space no one can hear you scream.....In a seven no one can smell your bottom ! It`s not yours,it`s............. R7 NOW well actually MINE now!! Link to comment Share on other sites More sharing options...
Jason Plato Posted November 1, 2005 Share Posted November 1, 2005 If the bearing is screeching and clattering then its knackered ☹️. placing more pressure or pre load on it may quieten it down but its essentially knackered and will fail sooner or later ☹️ . Link to comment Share on other sites More sharing options...
anon7 Posted November 1, 2005 Share Posted November 1, 2005 But it's only done about 700 miles since it was put in ☹️ 🙆🏻 🙆🏻 🙆🏻 🙆🏻 Shaggers In space no one can hear you scream.....In a seven no one can smell your bottom ! It`s not yours,it`s............. R7 NOW well actually MINE now!! Link to comment Share on other sites More sharing options...
John Vine Posted November 8, 2005 Share Posted November 8, 2005 I ride the clutch alot during road driving (a bad habit) and (touch wood) I've not had a CRB fail. I also have a very heavily sprung clutch so the CRB works hard when used. I'd agree with Rob, preload doesn't seem to be what causes them to fail from my limited experience.I believe it's the lack of preload that causes the problem, so riding the clutch (gently, at least) could well be beneficial! I would say that CRB failure is caused by NO pre-load. Imagine what's happening to a bearing with no pre-load. It's going from 0 to 4000 rpm (or more!) almost instantly. Pre-load keeps the bearing turning all the time but with little load.Exactly so, IMO. I cured it by shortening the clutch return spring and connecting it to the clevis pin instead of the drilled hole in the arm.I think you've done the right thing, but it may just be too late. Once the CRB starts making screeching noises, it's life is going to be short. JV Link to comment Share on other sites More sharing options...
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