PodOne Posted April 15, 2021 Report Share Posted April 15, 2021 Evening folks. As ever a few question to you. I've managed to gather all the different current/amp figs for the fused and unfused circuits and plan to use a number of additional relays and fuse currently unfused circuits. The one amp figure I'm struggling to find is the current draw for the original starter motor so I can rate the required thin wall cable. 1) Anyone know the current draw for the OEM Lucas starter? 2) I was also toying with fitting a Wasp high torque unit and the only figure I can find is 41 amp? 3) Is it worth fitting a high current relay for either to take the load off the ignition switch? Or is this overkill. Thanks Andy Quote Link to post Share on other sites
RobH Posted April 15, 2021 Report Share Posted April 15, 2021 1) If you mean the original starter solenoid, its 6Amps. 2) the wosp solenoid (ignition trigger as they call it) will draw a fair bit more than the Lucas one as it is throwing the starter into engagement as well as making the contact for the motor, so that is probably the 41A peak they quote as 'pull' current and 11A to hold in while starting. 3) Not worth it for the Lucas as thats what the solenoid is for. It is needed for the wosp if you connect it as pre-engaged, as 41A is a bit much for the original switch and wiring even though it is only a short time. The easy way to do that is to retain the original solenoid for powering the wosp so it is acting as a relay, and leave the link in place on the motor as they describe in the fitting instructions. "Retain the black insulated link wire which is fitted between the ignition trigger terminal and the main battery stud. This means the original bulkhead mounted solenoid is still in use." http://www.wosperformance.co.uk/products/starter-motors/fitting-instructions/ Quote Link to post Share on other sites
Lebro Posted April 16, 2021 Report Share Posted April 16, 2021 That is exactly what I did. move the heavy cable which goes to the starter from the lower terminal on the solenoid to the same as the battery cable., then add a wire from the lower terminal down to the excitation terminal (small one) on the starter. Then you can still use the rubber button on the solenoid to start. Bob. Quote Link to post Share on other sites
PodOne Posted April 16, 2021 Author Report Share Posted April 16, 2021 Thanks both for the feedback should have been more clear in my thinking so yes 6 amp for the solenoid. Confused now! So if I stick with the OEM Lucas no advantage in changing the wiring arrangement. If I go Wasp relay required if so how? as 41A through the switch seems like asking for trouble if running it as pre-engaged set up I guess there must be a lot of Tr6's wired like this. Retaining the original starter solenoid Rob seems not very elegant as my TR6 has no bulkhead relay (unlike both your TR3's) So I use the ignition switch trigger wire to the starter solenoid to trigger a 50A relay to the Wasp or could I retro fit the one you use in your TR3's. Andy Quote Link to post Share on other sites
RogerH Posted April 16, 2021 Report Share Posted April 16, 2021 (edited) Hi Folks, am I reading this wrong - surely the Wosp solenoid doesn't take any more current than the separate solenoid (an amp at best. Roger Edited April 16, 2021 by RogerH Quote Link to post Share on other sites
stuart Posted April 16, 2021 Report Share Posted April 16, 2021 Its different for a 6 as they already have a pre-engaged starter unless its a really early US spec that still has an inertia one. If you going to a WOSP then just wire it the same way as your original, it comes with instructions how to do it. You shouldnt need to add any thing more than a relay for the ignition switch. Stuart. Quote Link to post Share on other sites
RobH Posted April 16, 2021 Report Share Posted April 16, 2021 (edited) 5 minutes ago, RogerH said: surely the Wasp solenoid doesn't take any more current than the separate solenoid (an amp at best. Not according to their technical information Roger. Don't forget it is shifting the pinion, not just making a contact. see 'pull current' and 'hold current' here: http://www.wosperformance.co.uk/products/starter-motors/starter-performance/1-4kw-denso-performance/ (also the round TR starter solenoid has a 2 Ohm winding, so must take 6 amps) Edited April 16, 2021 by RobH Quote Link to post Share on other sites
RogerH Posted April 16, 2021 Report Share Posted April 16, 2021 Thanks Rob. That is surprising. So using the existing solenoid on my 4A to power the Wosp motor and its solenoid is a good thing. Roger Quote Link to post Share on other sites
RobH Posted April 16, 2021 Report Share Posted April 16, 2021 Absolutely necessary I would have said Roger. Quote Link to post Share on other sites
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