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J-Type Overdrive wiring Burn-Out


BertieBoy
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I have a Mk1 Vitesse with a later J-Type overdrive conversion. I recently experience smoke from the gear stick gaiter and removed the gearbox tunnel, two pinched wires seem to be shorting across and the WHITE wire seemed burn't out and melted. I replaced both wiring with 5A and also re-wired the switch in the gear lever - brilliant all working! - however today.. suddenly a load of smoke and a burn't out wire. I have spent a bit of time reading and it seems that 5A wire might be the problem as it is in-sufficient for the temporary load whilst the plunger moves (especially if it gets stuck) - am I right? do I need heavier wire (and why does only the WHITE side of the circuit burn out)? - P.S: the overdrive has always worked fine and always engages

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First thing i would say is if it doesn`t have one get a fuse in there before rewiring,Fuses are there to prevent this before its gets to the melting stage or worse a fire.

 

J types don`t take much current,your problem must be shorting somewhwere,mine has a 3 amp fuse inline with the supply.

Steve

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Just to be clear which side is the solenoid ?

 

Dtype its drivers side and J type is passenger side

only ask as j type takes little current where as a Dtype has the 10amp pull in coil backed up by a 0.5amp holding coil all changed over by a switch in the back of the solenoid

 

amd wires down the gear stick are very prone to chafe its best to use a silcon sleeved wire as this takes the heat and is far more flexible also check for shorts where the wires join the switch and dont contact the gear stick when the cap, is fitted

 

depending on how its wired a white is generally the colour for an ignition controlled feed

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Yes, its the white wire side that burnt out, not sure where the solenoid is (I only know its a J Type as I have the receipts from previous work by the former owner and it was fitted professionally as a conversion) where do I find it? - originally the wires had chafed between the stick and the gaiter (which I think caused the original problem) but when I pulled the wires again this 5A wire looked pretty soft and they might have chafed again on the gaiter (which might explain why its been OK for a week before it broke through), I did check for contact between switch and gear stick and wrapped it with insulation before fitting into the gear stick so don't think the problem was there - I bought some thicker 17A wire today as well as some heat shrink to protect the wires and will wire it back up and see how it goes - however this feeds into the fuse box (passenger side on engine side of bulk head) and theres a 17A fuse in there - is that too much?

 

Im hoping the heavier duty wire will make it a little more robust and perhaps solve the issue?.

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I would imagine the 17A fuse is fine as just referred to the Haynes and that states that the Vitesse 2ltr had two 35 amp fuses fitted - I have one 35 amp and one 17 amp - I am hoping that this is simply me repiaring what was a simple chafed wire with wire that was too light for the load. appreciate any thoughts.

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You will find a 35 amp blow fuse is rated at 17amp continuous so most are marked 35/17

so really to heavy for a j type 10 /5should be safe

 

With tunnel off its easy to see where the solenoid is located , from under the car its just about visible

with some groveling the solenoid is a cylindrical unit about 3" long and 1.5 " diameter

j is lh side d is rh side

 

the data plate will tell you also but again its tunnel off to find it.

 

pete

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Cheers Pete - found it! definitely on the passenger side (cylindrical black solenoid bolted on right down low). I have put 17A wire back in from the gear stick switch, individually shrunk wrapped them to stop them pinching near the gear level gaiter and have also got an inline fuse to install up close to the original fuse box before switching it all back on. will try a 7.5A or 10A fuse in it first and see how it goes, if I keep blowing fuses then I will have to look elsewhere for faults but I should at least avoid another burn out!

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If gear stick wiring comtinues to give problems which they do, you could consider changing to a column

stalk switch ( needs adifferent colum cowl )

certainly trouble free ,, stick switch or column switch love or hate them its down to

preference amd reliability

 

Keep plenty of free harness at the base of the stick to cope with gaitor chafe and the amount of movement required

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I think you'll have an even greater chafing problem with 17A wire.

'm assuming you're using the standard Triumph gear stick mounted switch with the cables entering the side of the shaft about halfway up.

The J-Type overdrive is the better unit but the controlling relay was omitted because of the lower currents involved, You should re-instate this if it's been removed as part of the conversion.

The easiest test to see if you have a relay in circuit is to put the car in third or fourth gear, switch the ignition on without cranking the engine, then turn on the O/D switch. If there's a relay in circuit you should hear a muffled clunk from somewhere on the bulkhead.Using a relay in the O/D circuit has two advantages:-

The O/D switch is only handling the relay operating current-less than 1A

The wiring to the O/D switch is the absolute minimum in size therefore reducing the risk of chaffing

I'm actually surprised that you've managed to stuff a 17A cable up the gearstick without peeling it like a banana. 

Even with this set-up a small inline fuse should be used in the controlling circuit- something like 2A if you're using a modern spade type. 

 

Cheers

 

Alan

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