TrafficMan Posted June 25, 2020 Report Share Posted June 25, 2020 Last year, I purchased a late 73 Mk3 GT6 totally dismantled but importantly missing its swingspring. At the last Stoneleigh spares meet I managed to purchase what I was told was the correct 5 leaf spring for my car. Upon trial fitting it to my diff yesterday I ended up with what you can see in the attached photo, with associated gaps. As I've never seen one assembled, does this seem correct. It just appears to me that the machined slot in the top of my diff is not deep enough to fully take the thickness of the lower leaf. Or is it correct and I'm at fault ?. Any thoughts greatly appreciated. Paul Link to comment Share on other sites More sharing options...
johny Posted June 25, 2020 Report Share Posted June 25, 2020 I suspect that the bottom plate is the wrong one if it has 6 holes and not 4. However don't know what difference this will make.... Link to comment Share on other sites More sharing options...
Colin Lindsay Posted June 25, 2020 Report Share Posted June 25, 2020 I've seen them like that before; I know from experience not to say "they're all like that" but they may be... as long as the bottom leaf is securely clamped it's fine. Link to comment Share on other sites More sharing options...
Badwolf Posted June 25, 2020 Report Share Posted June 25, 2020 I had dreadful trouble last year with the spring assembly on my 72 MkIV spit. You can find details here... https://forum.tssc.org.uk/topic/2623-back-to-the-bonnet-nose-to-tail-1972-spitfire-mkiv-restoration-upgrades/?page=28 towards the bottom of the page onwards. There may be something there which may help you. Link to comment Share on other sites More sharing options...
TrafficMan Posted June 25, 2020 Author Report Share Posted June 25, 2020 Thanks for your thoughts Johny & Colin and interesting thread Badwolf. Good nighttime reading there. Link to comment Share on other sites More sharing options...
Badwolf Posted June 25, 2020 Report Share Posted June 25, 2020 Only when you can't sleep. It was kept so that a lot of the help that everyone has given me is kept together. I should do some sort of index one day, if only for my own use. 1 Link to comment Share on other sites More sharing options...
Colin Lindsay Posted June 25, 2020 Report Share Posted June 25, 2020 The problem is that I suspect that may be a Spitfire 1500 spring; 5 leaves, ok, but different to the proper GT6 spring. The GT6 spring has 5 leaves too , but is actually softer than the Spitfire spring. I had one on my early GT6 and it was terrible, so obtained a NOS GT6 MK3 swing spring and that transformed the handling. I'm wondering if the bottom leaf is actually thicker thereby causing the lift; but having said that, this would mean that GT6 diff cases would have to be different to Spitfire cases to accommodate the shallower spring, and that's not the case. I'm almost certain that mine sat like that, too, when I first did the conversion, and caused no trouble. Link to comment Share on other sites More sharing options...
TrafficMan Posted June 25, 2020 Author Report Share Posted June 25, 2020 Thank you Colin. Very useful table. I will undertake some measuring tomorrow. 159654 is the part number my parts catalogue says I should have so some measurements should guide me to what I have. Paul Link to comment Share on other sites More sharing options...
Badwolf Posted June 25, 2020 Report Share Posted June 25, 2020 The slot in the diff definately looks to be shallow, the spring looks ok. Could the diff be a swapsy? From my own experiences that plate will bend if torqued down onto fresh air. Link to comment Share on other sites More sharing options...
TrafficMan Posted June 25, 2020 Author Report Share Posted June 25, 2020 That is a possibility. I will ask the previous owner as to what he knows. Paul Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 26, 2020 Report Share Posted June 26, 2020 If the bottom plate needs a gap to ensure the lower leaf is firmly clamped to the diff case , no gap could leave it 'loose' Pete Link to comment Share on other sites More sharing options...
Waynebaby Posted June 26, 2020 Report Share Posted June 26, 2020 Hi TrafficMan, If it helps, I'm on my second spring on my Mk3 GT6 and both the new spring and the one it replaced (which I'm assuming was the original) sit on the differential case like yours. Wayne Link to comment Share on other sites More sharing options...
johny Posted June 26, 2020 Report Share Posted June 26, 2020 From what I can see the correct bottom plate looks thinner and slightly wider with shamfered edges. It does also look more prone to bowing by over tightening... Link to comment Share on other sites More sharing options...
TrafficMan Posted June 26, 2020 Author Report Share Posted June 26, 2020 Hi Wayne & Johnny and all who have contributed to my thread. Whilst scratching my head over it this afternoon, I decided to part it from the diff and give it a wipe over. Thank goodness I did for the answer appeared before my eyes. 159654 emerged from beneath the grime which proves I have the correct spring. I just need to check with the previous owner regarding the originality of the diff. Many thanks though to all who contributed to answering my question. Paul Link to comment Share on other sites More sharing options...
Badwolf Posted June 26, 2020 Report Share Posted June 26, 2020 I would shim the gap with some washers. Having seen what the 'professional' guerillas did with mine paranoia rules. Link to comment Share on other sites More sharing options...
TrafficMan Posted June 26, 2020 Author Report Share Posted June 26, 2020 Never a fan of gaps myself but as Wayne says, it could be correct at that. Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 26, 2020 Report Share Posted June 26, 2020 all diffs have the same spring slot ,be they fixed or swinger , there must be a gap you have no other way of ensuring the bottom leaf is clamped solid , its in the design pete 1 Link to comment Share on other sites More sharing options...
TrafficMan Posted June 27, 2020 Author Report Share Posted June 27, 2020 On 25/06/2020 at 21:41, johny said: I suspect that the bottom plate is the wrong one if it has 6 holes and not 4. However don't know what difference this will make.... Johny, you are correct. My clamp plate does have 6 holes instead of 4. Looks like its been changed over for some reason in the past. Just ordered the correct one from Canleys. Link to comment Share on other sites More sharing options...
johny Posted June 27, 2020 Report Share Posted June 27, 2020 Great, if the rubber pad thing is in there and you clamp it all up to the correct torque I think you're good to go.... Link to comment Share on other sites More sharing options...
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