Nigel Clark Posted June 7, 2021 Report Share Posted June 7, 2021 I'm converting my GT6 to an electronic speedo that can be home-calibrated to match its 3.27:1 final drive and wheel/tyre combination, so I need to fit an electronic sensor to drive the new speedo. Rather than fit a bolt counting sensor by the propshaft, I like the neatness of the sensors that replace the (now redundant) speedo angle drive on the side of the overdrive. Revington TR have one that's suitable but it's expensive at £66: https://www.revingtontr.com/product/rtr8558-1/name/sensor-speedo-drive I think something like this Brantz sensor from Demon Tweeks would do the job cheaper: https://www.demon-tweeks.com/brantz-speed-sensors-241419/?sku=BNZBR4&istCompanyId=a2904180-3a7d-4e56-b876-cf81c9512180&istFeedId=6fbc4b04-fd28-4ce1-8513-835c8f118690&istItemId=wptilaxlm&istBid=t&gclid=Cj0KCQjwh_eFBhDZARIsALHjIKfn4xcRmayYspw7ENsutJ2ZJB585xjkuaGz8S6EclCS-eO2_s-Oa-waAsF8EALw_wcB&gclsrc=aw.ds Does anyone know the thread type on the Laycock overdrive's speedo output? And are all Laycock speedo threads the same, as I plan to swap the D-type overdrive for a J-type in the fairly near future? Thank you in advance. Nigel Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 7, 2021 Report Share Posted June 7, 2021 now i have that thread size written in a manual somewhere cant find it the demon tweaks smiths looks the part my only use of J type is on the mk2 2000 and thats not a threaded adaptor but a plain bush and cable held in with fork and setscrew very different Pete 1 Link to comment Share on other sites More sharing options...
Nigel Clark Posted June 7, 2021 Author Report Share Posted June 7, 2021 Thank you Pete. On the J-type I have on the bench, the fork in the overdrive holds a threaded output adapter with an approx 3/4" diameter thread. I think Demon Tweeks Smiths side is to fit the normal Smiths cable end, more like 1/2". So I'm still not sure. 18mm is close to 3/4" but would Laycock and Smiths have used a metric thread back in the day?? Does anyone know the thread type for sure? Nigel Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 7, 2021 Report Share Posted June 7, 2021 its daft i have this from previous questions but its done a runner i blame covid or maybe ageism Ha its hiding somewhere is th DT unit to fit the gearbox or the speedo end of the cable as thats nearer 1/2" i have an angle drive will have a play with some taps Pete Link to comment Share on other sites More sharing options...
Nigel Clark Posted June 7, 2021 Author Report Share Posted June 7, 2021 The sensor needs to screw into the speedo output on the overdrive, where the normal angle drive would normally attach. As above, the thread is approximately 3/4" diameter and fairly fine pitch. Nigel Link to comment Share on other sites More sharing options...
Mathew Posted June 7, 2021 Report Share Posted June 7, 2021 If imperial is it not defined in threads per inch by the inner size? Count the threads, probably 22tpi? 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 8, 2021 Report Share Posted June 8, 2021 another idea https://www.caigauge.com/documents//pdfs/emp34-1kit-388.pdf it is likely the cable fitting in the speedo is 1/2 BS Cy and the thread on the gearbox drive is 23/32" BS Cy at 26tpi ( this is historical) wonderful !!! so you need a Bicycle.............. but a measure makes it 0.7440" 18,90mm so the bike idea is defunct there are thoughts its 3/4" or 19mm as some advertise it as these and counting the TPI at 8am is not going to happen sorry not getting very far ha !! Pete Pete Link to comment Share on other sites More sharing options...
Nigel Clark Posted June 8, 2021 Author Report Share Posted June 8, 2021 Thank you Pete. Maybe I should stop being so tight and pay for the Revington sensor which will definitely fit. Nigel Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 8, 2021 Report Share Posted June 8, 2021 the brantz /smiths option one should have the right thread what i like is the statement below make your mind up its either inch or metric ...more |Ha !!! many sites quote Speedo Angle Drive for MGB & Triumph TR, Healey Part 021-511 or 120694. New high-quality Smiths Reproduction speedometer gearbox angle (Smiths No, BG2402-05) drive as fitted to; Rover P6, MGB & Triumph TR’s and the large capacity Healey's (GB0163). Also used on the speedometer head of the Aston Martin V8 models from the 1969 DBS, and V8's 1972 to 1980. Internal and external thread size; 3/4” (19mm approximately). Supplied complete with special copper fixing washer which must be used when fitting, ratio 1:1 Link to comment Share on other sites More sharing options...
Mathew Posted June 8, 2021 Report Share Posted June 8, 2021 On a quick side question! Why put ratio 1:1 as really its not a ratio but a direct drive, just wondered? Link to comment Share on other sites More sharing options...
johny Posted June 8, 2021 Report Share Posted June 8, 2021 well direct drive could imply straight through like when you have the cable connected to the gearbox. These units definitely have gears in them but they just happen to be the same size... Link to comment Share on other sites More sharing options...
daverclasper Posted June 8, 2021 Report Share Posted June 8, 2021 On 07/06/2021 at 19:05, Pete Lewis said: my only use of J type is on the mk2 2000 and thats not a threaded adaptor but a plain bush and cable held in with fork and setscrew My setscrew on J Type, was a bit loose, I found out today. I tightened it up (a bit tighter than previously), though can the fork be overtightened and squash the seal or other things too much?. Dave (AKA, worrier, too much) Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 8, 2021 Report Share Posted June 8, 2021 Dave you do worry ....all of us Ha hand tight wont upset anything the seal is an O ring on the speedo housing to case and a small proper oil seal on the speedo drive , how the cable is attached is outside of any gearbox oil zones they are all down under you clamp thingy Pete Link to comment Share on other sites More sharing options...
68vitesse Posted June 9, 2021 Report Share Posted June 9, 2021 From an earlier thread. https://forum.tssc.org.uk/topic/3311-angle-drive/ Regards Paul Link to comment Share on other sites More sharing options...
Nigel Clark Posted June 9, 2021 Author Report Share Posted June 9, 2021 22 minutes ago, 68vitesse said: From an earlier thread. https://forum.tssc.org.uk/topic/3311-angle-drive/ Regards Paul Thank you Paul, very helpful. I had a feeling this info was already on the forum but couldn't find it when searching. Nigel Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 9, 2021 Report Share Posted June 9, 2021 this time i will write it in the parts list not the little black book Ha Pete Link to comment Share on other sites More sharing options...
Andy M Posted June 17, 2021 Report Share Posted June 17, 2021 I used the speedo cable adapter with a Brantz on my TR4. Worked nicely. So you could use that, save a few quid, and use a stub of speedo cable - then it'll always fit something if gearbox/OD is converted. Or is that a bit too much of a bodge 🤔? 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 17, 2021 Report Share Posted June 17, 2021 Andy youre supposed to be fixing my computor not playing on the forum or its got you Hooked ha Pete Link to comment Share on other sites More sharing options...
Nigel Clark Posted June 17, 2021 Author Report Share Posted June 17, 2021 Thank you to all for your suggestions. In the end, I decided to pay extra to get a sensor that's guaranteed to fit easily, so have ordered from Revington. Nigel Link to comment Share on other sites More sharing options...
Andy M Posted June 18, 2021 Report Share Posted June 18, 2021 18 hours ago, Pete Lewis said: Andy youre supposed to be fixing my computor not playing on the forum or its got you Hooked ha Pete Worryingly, I'm hooked.... Link to comment Share on other sites More sharing options...
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