Freebird Posted March 2, 2014 Share Posted March 2, 2014 Hi everyoneBit miffed to say the least. Having swapped the rather tiered 4 speed for a J type OD box in the 1500 Spit, the clutch appears to be slipping. It's either that or the OD is slipping (god forbid)It does it in 2nd gear when the OD is not switched in, so I don't think it can be the OD - but please tell me if I'm wrong.If it is the clutch, I have a theory as to why this might be happening, so just want to discount the OD.CheersGlen. Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted March 2, 2014 Share Posted March 2, 2014 Glen,In general, main clutch slip occurs in the high gears (where it sees the the highest torque loading) whereas OD slip occurs in the lower gears (where it sees the highest torque loading).If you can get slip in second but not third or fourth I'd be fairly confident it's the OD. You'll probably find you can induce it in 1st as well. Temporarily rewiring the OD so it will operate in 2nd might help prove the matter also.Sorry is that is not the answer you were looking for....... :-/Nick Quote Link to comment Share on other sites More sharing options...
Freebird Posted March 3, 2014 Author Share Posted March 3, 2014 Thanks NickNot really what I wanted to hear, but need the bitter truth. Looking at the manual though, it seems the drive is taken by a unidirectional clutch when the OD is not activated - can this slip? I thought they were mechanical like a starter clutch on a motorbike. "Sprang" I think the word is.Glen. Quote Link to comment Share on other sites More sharing options...
MadMitch82 Posted March 3, 2014 Share Posted March 3, 2014 Don't know if this is any help, it does mention about slip though.http://www.canleyclassics.com/?xhtml=xhtml/infodatabase/overdrivesjtype.html&xsl=infodatabase.xsl Quote Link to comment Share on other sites More sharing options...
Freebird Posted March 3, 2014 Author Share Posted March 3, 2014 8266 wrote:Don't know if this is any help, it does mention about slip though. http://www.canleyclassics.com/?xhtml=xhtml/infodatabase/overdrivesjtype.html&xsl=infodatabase.xslThanks MM, I forgot all about Canley's rather excellent advice. This bit worries me as it's just the symptom I am getting."Later Dolomite and Spitfire overdrives (after 1978) have a badly made centre to the one way bearing and from around 30000 miles can give the impression of clutch slip, quick getaways from the lights can lead to an embarrassing lack of forward motion."Glen. Quote Link to comment Share on other sites More sharing options...
Freebird Posted March 3, 2014 Author Share Posted March 3, 2014 But then looking at the exploded diagram, the "one way bearing" is a sprang clutch as I thought, so hard to see how it can slip........... Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted March 3, 2014 Share Posted March 3, 2014 Yes, could be the sprag clutch. Not the end of the world as the OD specialists will be able to sort you out a new one. Can be DIY fitted too - but gearbox out again and OD off it unfortunately.Nick Quote Link to comment Share on other sites More sharing options...
Clive Posted March 3, 2014 Share Posted March 3, 2014 Glen, maybe worth speaking to pete? he may have a few parts laying about. Meeting on Wednesday......(usual pub suddenly shut though, so at the Green Man) Quote Link to comment Share on other sites More sharing options...
Freebird Posted March 3, 2014 Author Share Posted March 3, 2014 cliftyhanger wrote:Glen, maybe worth speaking to pete? he may have a few parts laying about. Meeting on Wednesday......(usual pub suddenly shut though, so at the Green Man)Cheers CliveIt would be great to see you all again, but will have to wait 'til next month as I can't make Wednesday. Good to see Martin's car on the front of the Courier :) Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted March 3, 2014 Share Posted March 3, 2014 http://www.rimmerbros.co.uk/Item--i-NKC17Other suppliers exist and are most likely cheaper............ such as these guyshttp://www.overdrive-repairs.co.uk/buy_spares.php?cat=J+Type+Spare+Parts+Listor these guyshttp://www.odspares.com/phdi/p1.nsf/supppages/odspares?opendocument&part=2as well as the usual suspects.Nick Quote Link to comment Share on other sites More sharing options...
Freebird Posted March 4, 2014 Author Share Posted March 4, 2014 Cheers Nick Quote Link to comment Share on other sites More sharing options...
Freebird Posted March 5, 2014 Author Share Posted March 5, 2014 The MG has a binding rear brake, so I drove the Spitfire 25 miles to work this morning and there was no sign of any slip even under pretty severe 5000 RPM provocation in 2nd gear.I maybe over optimistic, but perhaps it needed to settle down after lord knows how long out of use............ Quote Link to comment Share on other sites More sharing options...
Freebird Posted November 2, 2014 Author Share Posted November 2, 2014 It's been a while.The OD continued to slip when disengaged and was diagnosed by the very knowledgable guys from OD spares (thanks for the link Nick) as a poorly uni-directional clutch. This ties up with the Canley site info where is says that late overdrives had a badly made inner part to it. Joe has been driving it like that for several months just being careful not to give it too much welly but last weekend the main clutch started to drag badly - see other post, so the box had to come out and I did both jobs - as you would.Buying the parts for the overdrive and rebuilding it yourself is not difficult and saves a packet over a recon unit plus you get a sence of satisfaction when it all works afterwards (hopefully) and know it inside out - quite literally. I got the parts from OD spares too - delivered next day. Pukka.Glen. Quote Link to comment Share on other sites More sharing options...
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