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Starter terminals: Coarse Or Fine?


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Good morning. As a follow on from my post last week about my TR6 charging issues, I thought I would ask for some more advice on my latest problem...

Whilst looking for the source of my charging problem, I found that the nut that holds the cables onto the starter motor were indeed lose (although this wasn't the cause of the charging problem). Naturally, I tried to tighten it, but the nut wouldn't tighten. It had obviously been loose for a while,  as the cable 'eyes' had worn away the thread on the contact stud. It is a 'WOSP' hi-torque starter, & the thread is M8. I've tried cutting a new thread, but there isn't enough 'meat' (or copper/brass in this case) for the nut to grip onto.  I'm now thinking of cutting a 5/16" thread, as this is the next smallest size, & a nut might have a better chance of gripping. My question is,  should  I go 'coarse' (UNC) or 'fine' (UNF)? I have the tools to cut either, loads of 5/16" UNF nuts, but not sure if I've got any UNCs.  I realise this might not work at all, but it's got to be worth a try!

As ever your expertise & kind advice will be greatly appreciated,

Cheers,

Paul.

Edited by TR Paul
gramatical!
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Paul,

If there is enough length to the stud why not just use a couple of extra washers under the fixing nut.

Graham

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There won't be enough diameter left for a 5/16 thread if the M8 has been completely worn away Paul. The core diameter of an M8 x 1 thread is only 6.59mm or just over 1/4 inch.  If you cut that at 5/16 the thread will be vestigial and very weak.

If you went down to 1/4 for which there is enough material, a fine thread would leave slightly more core diameter. 

 

I think if it was mine I would try to make up a clamp fitting instead. 

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Hi Paul,

5/16 unc would probably do it - do you have two nuts to suit?

If you mess it up and are you able to take the contact cover plate off and get to the head of the terminal bolt?

If so there is possibly a terminal bolt in this kit that would fix it.

https://www.ebay.co.uk/itm/MAZDA-BONGO-2-5TD-FORD-FREDA-2-5TD-DENSO-STARTER-MOTOR-CONTACT-REPAIR-KIT/293191698249?hash=item4443964749:g:TxAAAOxy8HlSdC7l

Cheers

Peter W

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Hi Pete, Rob & Graham. Thanks for your replies; You raise some interesting points. Sadly there isn't enough length on the stud for any washers; one of the downsides of the 'WOSP' starter is that the stud is already 1/2" to short at the best of times, & I've always used 'thread-lock' on the stud. I think I've just found a slim 5/16" UNC nut on my old O/E Lucas starter, so I might try that route.  My plan (until I had my latest 'brainwave') was to take the starter off (a job I'm trying to avoid....), & get it repaired at a alternator/starter motor specialist I know of (or get my O/E Lucas unit rebuilt). This is of course what I shall be doing, if I make a pigs ear of the stud....

Cheers,

Paul.

Edited by TR Paul
gramatical!
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2 hours ago, TR Paul said:

Good morning. As a follow on from my post last week about my TR6 charging issues, I thought I would ask for some more advice on my latest problem...

Whilst looking for the source of my charging problem, I found that the nut that holds the cables onto the starter motor were indeed lose (although this wasn't the cause of the charging problem). Naturally, I tried to tighten it, but the nut wouldn't tighten. It had obviously been loose for a while,  as the cable 'eyes' had worn away the thread on the contact stud. It is a 'WOSP' hi-torque starter, & the thread is M8. I've tried cutting a new thread, but there isn't enough 'meat' (or copper/brass in this case) for the nut to grip onto.  I'm now thinking of cutting a 5/16" thread, as this is the next smallest size, & a nut might have a better chance of gripping. My question is,  should  I go 'coarse' (UNC) or 'fine' (UNF)? I have the tools to cut either, loads of 5/16" UNF nuts, but not sure if I've got any UNCs.  I realise this might not work at all, but it's got to be worth a try!

As ever your expertise & kind advice will be greatly appreciated,

Cheers,

Paul.

Hi Paul,

I would get onto WOSP direct to see if they will put a new power fitting on for you, if you send the motor back to them or take it back ! I have found them very helpful when I had a problem with the klick and lock plug. The hard part was to find out where they were in the UK, see below:

Luke Motor sport.Unit 8 Anglo Business Park, Seaton Close, Aylesbury HP19 8UP Tel; 01296415044.

My ignition S/W burnt out due to the supply current required to activate the solenoid. When I was at WOSP, I asked for a data sheet on my Starter Motor to my surprise the Start/pull current to the solenoid is 41 amps? I queried this and they said that this was correct and you should always use a relay? But it does not tell you that in your fitting instructions? I have now corrected this on my car!!!! 

Bruce.

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Hi Bruce,

41 amps for a solenoid sounds a lot to me. Why?

Best regards,

Waldi

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Hi Bruce, thanks for the WOSP info....that might be useful.

Best wishes,

Paul.

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4 hours ago, Waldi said:

Hi Bruce,

41 amps for a solenoid sounds a lot to me. Why?

Best regards,

Waldi

Hi Waldi!

That's what their spec sheet says, this what I queried, as already stated but when engaged it then drops down to 11 amps.

Bruce.

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Thanks Bruce.

Looks like it has the same working principle as an A-type OD solenoid, but with higher current (power). In fact it makes sense to me considering the required force to activate the starter motor. I just did not realize the current was that high. 
Best regards,

Waldi

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2 minutes ago, Waldi said:

Thanks Bruce.

Looks like it has the same working principle as an A-type OD solenoid, but with higher current (power). In fact it makes sense to me considering the required force to activate the starter motor. I just did not realize the current was that high. 
Best regards,

Waldi

Hi Waldi,

I bet that very few if any use a relay to operate the Wosp Starter Motor???

Bruce.

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If you wire it as per the original system, so that the original starter solenoid still does all the switching, you already have a relay.

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From memory there is no separate starter relay on a TR 6 PI.  Ignition switch control goes to the pull in / pre engage solenoid on the starter motor.   Cars without a pre engage starter did have the separate starter solenoid.   TR 6 USA used an interlock starter relay after 1975, but that does not help here.   

 

Peter W

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I came across this topic for the first time, interesting. I do not see a relay for the solenoid in any of the TR6 wiring diagrams in my WSM. The solenoid is powered through the ignition switch directly. Maybe the short duration is a factor too, so the solenoid current cannot really overheat the switch. Off course, the contacts need to be clean.

Waldi

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Repair Kits UK can help you. I recently bought a repair kit for my High Torque starter in my 4a. Guys name is Carl Dawes on 01543 226222, cheers Ian.

Good info, didn't know about them, worth having the details....

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Thanks for all this good information. You might be interested  to know that I attacked the offending post with a 5/16" UNC die this morning. The starter is still on the car, & there isn't room to use the die holder, so I was just using my (cold!) fingers & mole grips.... so (surprise, surprise) that didn't work.....

Next step is to remove the starter, & try to do the job properly (no, not usually my style!).  The WOSP starters are a pain to remove, as the top bolt is replaced by a 3/8 UNF  stud, with a nut on the g/box side, & accessibility is severely restricted, which is why I was reluctant to remove the starter; it's a struggle to even get a spanner on the nut!  I did think of cutting the stud off with a Dremel,, but I'm not keen on sparks flying around, so close to the Injector manifolds..... Does anybody have any tips?

Cheers,

Paul.

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Hi Paul,

try to modify a ring spanner by cutting and welding, so you can hold the nut. A 2nd person might reach it from “down under”.

Waldi

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Hi Bill, a TR takes you to places you didn’t know they exist:)

Cheers,

Waldi

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Could you use a long brass manifold nut such as https://www.ebay.co.uk/itm/Brass-UNC-UNF-BSF-Manifold-Exhaust-Extra-Long-Nuts-MG-MGB-MIDGET-And-More/371181189384?var=640448074592&hash=item566c1f7908:m:mciNXCMI9sC-_X8CUSNPKvQ

take one brass bolt, perhaps 30mm long and cut the head off, dip in flux  screw 50% into the nut, screw the 50% remaining over the starter bolt and solder nut to both bolts. 

You now have a new brass threaded bolt admittedly longer than original to screw the terminals to.

Alan 

Edited by barkerwilliams
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Paul. 
cut an access hole in the gearbox tunnel cover and then you can access the top nut via a socket extension.  Removing / installing the starter is then a 10 min job.

good luck.

dave

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