daverclasper Posted June 19, 2018 Report Share Posted June 19, 2018 Hi. I think I may have a dodgy 30 amp relay (ice cube type) on overdrive. I have a spare 40 amp. Can I fit this please?. Thanks, Dave Link to comment Share on other sites More sharing options...
Anglefire Posted June 19, 2018 Report Share Posted June 19, 2018 Yes no problem as along as the fitting is the same - which is ruddy obvious. But you can get 4 and 5 pin relays and corresponding options for the which pin is missing. Link to comment Share on other sites More sharing options...
NonMember Posted June 20, 2018 Report Share Posted June 20, 2018 There are also five pin relays where the contacts are change-over and others where the NC pin is actually a second NO. That shouldn't be a problem, though, because you're almost certainly not using that pin. Incidentally, what type of overdrive? The D-type should have a really beefy relay, the J-type usually doesn't have one. Link to comment Share on other sites More sharing options...
daverclasper Posted June 20, 2018 Author Report Share Posted June 20, 2018 Thanks. It's a J Type. It was retro fitted to my none factory overdrive car years ago, by Canley, according to a reciept I have. I did wonder why?. Dave Link to comment Share on other sites More sharing options...
NonMember Posted June 20, 2018 Report Share Posted June 20, 2018 Well, having given the official "J-type doesn't need a relay" line, I should confess that two of my three have J-types with a cube-type relay fitted. This is because, in my experience, the column switch is a little delicate when switching a heavily inductive load. That said, the Vitesse managed to burn the relay contacts so I've now gone belt-and-braces (and suspenders). On both the Vitesse and the Spitfire, the column switch operates a 20A relay, the other side of which connects battery (brown wire) to the solenoid (preferably through a fuse but I don't have one at the moment). The solenoid terminal also has a heavy duty diode (1N5401) from ground (make sure the anode is ground and the cathode is on the solenoid). This conducts away the flyback current that causes arcing on the relay contacts. I also fitted a ceramic capacitor (100nF is enough) across the diode. This damps the flyback a fraction so that a normal diode is sufficient, rather than needing an ultra-fast Schottky one. Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 20, 2018 Report Share Posted June 20, 2018 yes J type solenoid only uses about 0.5 amp at the most and doesnt have to have a relay , but as said it can extend the switch life a D type takes over 10amp on pull in and 0.5a when engaged , so initial load does need a relay to preserve the switchgear Link to comment Share on other sites More sharing options...
Mad4classics Posted June 20, 2018 Report Share Posted June 20, 2018 55 minutes ago, NonMember said: Well, having given the official "J-type doesn't need a relay" line, I should confess that two of my three have J-types with a cube-type relay fitted. This is because, in my experience, the column switch is a little delicate when switching a heavily inductive load. That said, the Vitesse managed to burn the relay contacts so I've now gone belt-and-braces (and suspenders). On both the Vitesse and the Spitfire, the column switch operates a 20A relay, the other side of which connects battery (brown wire) to the solenoid (preferably through a fuse but I don't have one at the moment). The solenoid terminal also has a heavy duty diode (1N5401) from ground (make sure the anode is ground and the cathode is on the solenoid). This conducts away the flyback current that causes arcing on the relay contacts. I also fitted a ceramic capacitor (100nF is enough) across the diode. This damps the flyback a fraction so that a normal diode is sufficient, rather than needing an ultra-fast Schottky one. Interesting; you're trying to protect the column switch and relay contacts because of the inductive loads. However, adding a diode across the relay and the solenoid will act to slow their disengagement. Here's a link to an interesting application note on this from TE Connectivity:- http://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=13C3264_AppNote&DocType=CS&DocLang=EN They recommend a Zener + diode arrangement. David Link to comment Share on other sites More sharing options...
NonMember Posted June 20, 2018 Report Share Posted June 20, 2018 Sure, the recirculation diode slows the disengagement, but not by much. For 90% of applications, overdrive solenoids very definitely included, that extra few milliseconds makes sod all difference. Now if we were talking injector drivers, that's a very different matter. No simplistic recirc diode on them; the driver needs to withstand the flyback. Note, also, that I have NOT put a diode on the relay coil. The relay coil is small enough that the column switch is not in danger. The effect of slowing the contact opening, which that TE document discusses, is thus not relevant. Slowing the solenoid return means the hydraulic valve closes a bit slower, which contributes to the intentional damping of the pressure release (by having a very small bleed opening) for smoother shifts. Link to comment Share on other sites More sharing options...
Mad4classics Posted June 20, 2018 Report Share Posted June 20, 2018 Not sure I'd want to alter the dynamics of the cone clutch operation. I'll stick with dipping the clutch for a smoother shift. Link to comment Share on other sites More sharing options...
NonMember Posted June 20, 2018 Report Share Posted June 20, 2018 1 hour ago, Mad4classics said: Not sure I'd want to alter the dynamics of the cone clutch operation. I'll stick with dipping the clutch for a smoother shift. Entirely your prerogative. However, the effect of a flyback diode on the solenoid release rate is at most a tenth of a second. The J-type hydraulic system was explicitly designed to release the cone clutch a fair bit slower than that. Laycock did not intend for you to (need to) dip the clutch. Link to comment Share on other sites More sharing options...
daverclasper Posted June 20, 2018 Author Report Share Posted June 20, 2018 Thanks. Well. I wired in spare relay and switched O/D on. Didn't work and My amp meter in car went up to 30, or off the scale. Switched off straightaway. Realized I had wired it wrong. (poor eyesight). Didn't make a note of what I did wrong. Wired correctly, it now works, though wondering if I did any damage?. Cheers, Dave Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 20, 2018 Report Share Posted June 20, 2018 No smoke, sleep easy Ha Pete Link to comment Share on other sites More sharing options...
NonMember Posted June 20, 2018 Report Share Posted June 20, 2018 2 hours ago, daverclasper said: Thanks. Well. I wired in spare relay and switched O/D on. Didn't work and My amp meter in car went up to 30, or off the scale. Yes, that's why my lack of fuse is not a great situation ? Still, as long as the smoke didn't leak you're OK. Link to comment Share on other sites More sharing options...
Anglefire Posted June 20, 2018 Report Share Posted June 20, 2018 Its ok, you can get replacement smoke Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 21, 2018 Report Share Posted June 21, 2018 You could add a in line blade fuse holder in the main brown supply from the solenoid terminal to add some protection against mishaps Cant advise a rating , certainly around 30 to 45amps , not too high or the wiring will suffer before the fuse pops and shuts everything down Certainly easier than a full fuse box replacement and better than smoke and whip the battery terminal off syndrome. Link to comment Share on other sites More sharing options...
NonMember Posted June 21, 2018 Report Share Posted June 21, 2018 For a J-type the Triumph Standard 17A fuse rating is more than adequate. Link to comment Share on other sites More sharing options...
Clive Posted June 21, 2018 Report Share Posted June 21, 2018 This has always got me. Do you mean a 17A fuse that blows at 35A? They always look really chunky to my eye, but I guess offer some protection. A 15A fuse ( as in blows at 15A) is very thin in comparison. Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 21, 2018 Report Share Posted June 21, 2018 from on here somewhere there are two distinct types of fuses in use in the aftermarket the normal automotive ones , glass, ceramic, blade , will run a load of 17 amps and blow at 35 so you take care of any spikes there are some nasty glass ones ( got some in a assorted box) which have the flat bladed fuse wire inside marked as 35amp and thats all you get no protection till............ ka....boom well something like that Pete Link to comment Share on other sites More sharing options...
NonMember Posted June 21, 2018 Report Share Posted June 21, 2018 Yes, although a 15A blow fuse would probably be adequate if it's only the J-type solenoid it's feeding. The 17A (35A blow) fuses are for circuits expected to draw 17A. If you put 18A through them for long enough, they will blow. The 35A spec is when they go pop "instantly". To be honest, there aren't many failure modes that make a 5A circuit draw 10A. What you're protecting against is mostly accidental shorts, which will draw hundreds of amps if the wiring's up to it. Link to comment Share on other sites More sharing options...
Mad4classics Posted June 21, 2018 Report Share Posted June 21, 2018 3 hours ago, Pete Lewis said: from on here somewhere there are two distinct types of fuses in use in the aftermarket the normal automotive ones , glass, ceramic, blade , will run a load of 17 amps and blow at 35 so you take care of any spikes there are some nasty glass ones ( got some in a assorted box) which have the flat bladed fuse wire inside marked as 35amp and thats all you get no protection till............ ka....boom well something like that Pete There are several fuse rating standards around the world, this warning about USA standards you may have already seen. http://www.mgtoronto.com/pdf/Tech/fuses.pdf David Link to comment Share on other sites More sharing options...
Anglefire Posted June 21, 2018 Report Share Posted June 21, 2018 Fuses - and pretty much every protective device is IDMT - indefinite mean time - so will run indefinitely at the rates current but as the current goes up the time it takes to blow gets corresponding shorter. The better the device the more repeatable the timing. Mall the fuse is really doing is protecting the wiring. The device will probable be knackered if it really does blow the fuse Link to comment Share on other sites More sharing options...
Mad4classics Posted June 21, 2018 Report Share Posted June 21, 2018 8 hours ago, Anglefire said: Fuses - and pretty much every protective device is IDMT - indefinite mean time - so will run indefinitely at the rates current but as the current goes up the time it takes to blow gets corresponding shorter. The better the device the more repeatable the timing. Mall the fuse is really doing is protecting the wiring. The device will probable be knackered if it really does blow the fuse That's absolutely right; Lucas fuses however were rated by their blow "instantly" value. 1 Link to comment Share on other sites More sharing options...
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