stuart Posted June 25, 2015 Report Share Posted June 25, 2015 (edited) I suspect Alan T may well be able to supply the answers to this enquiry received yesterday. I would appreciate your help on the following. Some time ago my speedo cable broke leaving a small part in the speedo head. I replaced the whole cable and cleared the broken part out. Unfortunately it still didn’t work and further investigation showed the angle drive was chewed up too. When I bought the replacement angle drive I was advised that there was a modification, a copper washer as a spacer on the gearbox side of the angle drive. On fitting the new angle drive the speedo worked for few seconds and failed again showing no reading at all. I then checked the speedo drive gear which looked okay but I noticed the squared section inside its shaft was some way down and may not have been engaging with the cable properly. So I checked the old drive against a new drive gear which seemed to have the squared section further up the inside of the shaft, though not right to the top which I thought unusual, and so I fitted the new drive gear and also removed the copper spacer from the angle drive. The net result is the speedo does now work but not accurately. At lower speeds it’s not too bad but at higher speeds it is wildly inaccurate, reading too fast. I did check the number of teeth on the new gear before it was fitted and it was the same as the old one. Prior to the speedo cable breaking the speedo was accurate Your thoughts chaps. Stuart. Edited June 25, 2015 by stuart Quote Link to post Share on other sites
AlanT Posted June 25, 2015 Report Share Posted June 25, 2015 All the drives I have come across are 1 to 1 ratio. This includes Jags and Elans. Same gears in all of them. It's easy to check the ratio when the drive is out. Pen mark and a match stick. Some drives don't have a thread cut right to the end of the big knurled nut. These won't tighten without a washer. Some drives have the brass bearing sticking out of the body so they won't sit flat without a washer. Other drives look to me as if they would work fine with no washer at all. The square hole in my 4A gbox take-off is about 1.5in deep. The drives have a wire-stub sticking out by about 1in. It engages about 5/8in into the gbox. I built one, for Neil ntc, recently and his problem seemed to be that the drive cable from the speedo-head did not reach into the angle-drive far enough to make full engagement. Repro drives often have "dodgy" crimping in the pinion. https://flic.kr/p/rw1gC6 We need a bit more information really. When it says the speedo is inaccurate does this mean it "jumps about" or does it have a steady reading that is just "wrong". Quote Link to post Share on other sites
stuart Posted June 25, 2015 Author Report Share Posted June 25, 2015 I have just copied the entire enquiry here and sent him the link to it so hopefully he might give you the info you require Alan..I suspect though that the whole process may have now not done his speedo a lot of good so that may need a service too. Stuart. Quote Link to post Share on other sites
AlanT Posted June 25, 2015 Report Share Posted June 25, 2015 (edited) Maybe grease has got into the speedo head from the drive cable. This could allow the spinning magnet to drag the needle a bit. It's not easy to think of things that make the reading be too fast. Too slow has obvious causes. By the way I have a genuine Smiths drive that should work fine. Came to me with a broken wire and has my 3mm key-steel fix for this. It's like the one I did for Neil. Also the Smiths originals are so much better than the repros I will buy any broken ones and try to rebuild them. Edited June 25, 2015 by AlanT Quote Link to post Share on other sites
Guest ntc Posted June 25, 2015 Report Share Posted June 25, 2015 Stuart Alan is correct ,but the speedo may be damaged ( I ? that ) as the one Alan supplied is rock steady Quote Link to post Share on other sites
modelbuilder Posted June 30, 2015 Report Share Posted June 30, 2015 Alan T, I have sent you a PM. Rodders. Quote Link to post Share on other sites
Peter Cobbold Posted July 1, 2015 Report Share Posted July 1, 2015 My speedo ( TR6 J-type o/d) packed up suddenly. Investigated the right angle drive today by removing driver's seat and melting an access hole in the plastic gearbox cover ( thanks for the tip Niall). The speedo drive shaft retainer is a single, short 3/16inch (??) bolt through on a deliberately bent flange extension ( yes... nasty ! ). The bolt had mosty unsrewed leaving the r/a drive wobbling around. The square section cable had sheared. I suspect - dont actually know - that the screw allowed the ra drive to wobble in relation to the drive shaft, flexing the inner cable until it failed. A new ra drive was fitted. The screw has benn Loctited in after ensuring it was firmly home without pulling the drive retainer at an angle to the drive axis. A washer to act as spacer from the box-o-bits was needed to prevent that deliberately bent flange from pulling the retainer out of line. Dabs of waxoyl and a sheet of Flashband to seal the tunnel, and its ready for the next owner to spend another hot, sweaty afternoon fettling again. Peter Quote Link to post Share on other sites
John Morrison Posted July 6, 2015 Report Share Posted July 6, 2015 Alan T you have a PM. John. Quote Link to post Share on other sites
RogerH Posted September 23, 2015 Report Share Posted September 23, 2015 (edited) Hi Stuart, my speedo stopped working on Sunday. Yesterday I removed the drive cable but it was in good order. Trying to turn the square end gave no rotation - suggesting that the RA drive may be OK. Had a fiddle with various things but the speedo still refused to work. Today I removed the RA drive and found the connecting flex drive knackered as usual. As this RA drive was repaired by me in 1997 I thought 18 years was a fair life. So decided to repair it again. Firstly remove the broken munged cable. Find a suitable speedo or tacho cable. Cut off apprx 3". The round end was then tapped (hammered !!) into the gear shaft. This gave a very solid fix. A test drive showed it working OK. Roger PS - Hi Alan, I didn't mean to pinch your yellow background. It is a Halfords wet&dry package. Edited September 23, 2015 by RogerH Quote Link to post Share on other sites
stuart Posted September 23, 2015 Author Report Share Posted September 23, 2015 Roger that is how I repair them. Stuart. Quote Link to post Share on other sites
TR NIALL Posted September 23, 2015 Report Share Posted September 23, 2015 But what is causing the Munged Cable to Break? Quote Link to post Share on other sites
RogerH Posted September 23, 2015 Report Share Posted September 23, 2015 (edited) Hi Niall, Alan T has looked into this to quite a depth. Certainly on the repro's the gear teeth cause a fair bit of stiffness. This causes the the small flex cable to twist. There is probably a small amount of pulsing going on (not removed completely by the flywheel). Eventually the strands start to break. Eventually the last one goes. Alan has looked into using a solid steel square shaft - should be interesting to see what it does (we probably will not be here) For some reason I thought the internal gear was a bevel gear but it is not. It is a worm gear. When the internal cable breaks I thought you could assess this by turning the speedo end of the cable to see if it turned. Because it is NOT a bevel gear you will find the speedo end will not turn - your conclusion that all is well would be seriously wrong. You can't turn a worm gear from the out put. Interesting day ! Roger Edited September 23, 2015 by RogerH Quote Link to post Share on other sites
Guest ntc Posted September 23, 2015 Report Share Posted September 23, 2015 Roger Have you seen one of Alan drives? Quote Link to post Share on other sites
TR NIALL Posted September 23, 2015 Report Share Posted September 23, 2015 Hi Niall, Alan T has looked into this to quite a depth. Certainly on the repro's the gear teeth cause a fair bit of stiffness. This causes the the small flex cable to twist. There is probably a small amount of pulsing going on (not removed completely by the flywheel). Eventually the strands start to break. Eventually the last one goes. Alan has looked into using a solid steel square shaft - should be interesting to see what it does (we probably will not be here) For some reason I thought the internal gear was a bevel gear but it is not. It is a worm gear. When the internal cable breaks I thought you could assess this by turning the speedo end of the cable to see if it turned. Because it is NOT a bevel gear you will find the speedo end will not turn - your conclusion that all is well would be seriously wrong. You can't turn a worm gear from the out put. Interesting day ! Roger Thanks Roger,yes I've followed Alan's Post re the Drives from Day 1 as I was the Guinea Pig,I had sent him 4 Knackered ones to Play with and all came Home Refurbished,Exellent Job. Quote Link to post Share on other sites
RogerH Posted September 24, 2015 Report Share Posted September 24, 2015 Hi Neil, only in pictures and they look very neat indeed. Alan is quite a thorough engineer. Roger Quote Link to post Share on other sites
Guest ntc Posted September 24, 2015 Report Share Posted September 24, 2015 Roger Get one in your hand it makes the others look daft. Quote Link to post Share on other sites
BlueTR3A-5EKT Posted September 24, 2015 Report Share Posted September 24, 2015 (edited) Had one of these running on a TR with J type o/d for some years - came as a special one off sample when I was seeking an alternative supplier for the Lucas/Smiths/Caerbont thing. It is a bit bigger though. http://veethree.com/right-angle-drives.html Peter W Edited September 24, 2015 by BlueTR3A-5EKT Quote Link to post Share on other sites
AlanT Posted September 25, 2015 Report Share Posted September 25, 2015 (edited) A Smiths drive and some of the better repros can be turned from the "speedo-side" I made this tool specially to do this. It's a good way to test I've made em properly. Worn bearings, poor gears, end-float wrong and they stick when turned from the wrong side. All the bits of cable I had were a bit small to fit into the gbox. Of course I'm fussy about "fits". The gbox hole is 1/8in square. A 3mm square is a nice fit. Here is my first attempt at a repair solution: It's 1/8in square silver-soldered on the cable. I rejected doing this because of embrittlement of the wires. Don't think they will run for long enough. Then a forumite said he had run for years with a bit of Allen key!! So I made this, which is pretty easy: But then you need this to mate it to the gear, this is not so easy: Edited September 25, 2015 by AlanT Quote Link to post Share on other sites
AlanT Posted September 25, 2015 Report Share Posted September 25, 2015 (edited) By the way if you have a broken Smiths one its worth repairing because: This is a Smiths gear: And this is a typical repro these days: [ Note that there was an attempt to weld the wire-stub in place and you can see the area where this has cracked away. Edited September 25, 2015 by AlanT Quote Link to post Share on other sites
JPD Posted November 7, 2015 Report Share Posted November 7, 2015 This is interesting because my 67 TR4A (with overdrive) has a straight cable exit from the g/box, not an angled one. I bought the car as a restoration project so have never driven it, so I don't know if it ever had problems. I need to replace the drive and cable anyway as they are both broken, so it sounds like I should replace it with an angled drive. Are the new repro ones any better now or is it best to seek out an original one?? Thanks for any advice Jeff Quote Link to post Share on other sites
stuart Posted November 7, 2015 Author Report Share Posted November 7, 2015 I would always try to find an original if possible. Stuart. Quote Link to post Share on other sites
AlanT Posted November 14, 2015 Report Share Posted November 14, 2015 I will be making a batch of original Smiths drives, repaired with a solid-stubs in the near future. I have built up a stock of failed ones. It's quite common for the wire to break off of course. But also quite a few have an intact wire stub. But it's not holding firmly in the bevel. I'll post here again whenI get them done. There will be enough for everybody for a while after this! Quote Link to post Share on other sites
JPD Posted November 20, 2015 Report Share Posted November 20, 2015 I'd be interested in one Alan, have sent you a PM Jeff Quote Link to post Share on other sites
AlanT Posted November 22, 2015 Report Share Posted November 22, 2015 PM didn't come so I cleared out my inbox a bit. When I do the next batch I'll post some photos on here. Quote Link to post Share on other sites
AlanT Posted January 10, 2016 Report Share Posted January 10, 2016 (edited) Next batch done, photos as promised: These are all original Smiths. In most cases the wire-stub was rotating in the bevel-gear. This is a common failure mode. I have replaced this wire-stub with 3mm key-steel as discussed on this topic: http://www.tr-register.co.uk/forums/index.php?/topic/47968-pesky-right-angled-drives/page-3 Edited January 10, 2016 by AlanT Quote Link to post Share on other sites
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