Lt coil replacement.

FREE tuning and maintenance info, plus links to our original tuning pages that started it all off.
Meds
registered user
Posts: 191
Joined: Tue Jun 23, 2015 2:23 pm
Main scooter: Li125s
Contact:

Wed Nov 16, 2016 4:24 pm

I'm replacing the LT coil on a lambretta electronic ignition and converting it to DC.
This is the second one I have repaired, both showing the same symptoms of a burnt out LT coil and the pad that sits under that copper/aluminium washer has gone brittle and disintegrated and I'm trying to work out why they overheated?

When looking for a replacement coils I noticed that The vespa set up and the BGM set up all have a sandwich of
Coil-fibre pad-copper washer-heatsink , I can't work out what the heat sink is for as its insulated from the coil by what looks like a big fibre pad? The coil is further insulated as its in a plastic former, none of which are great for heat transfer.
From my days working with electronics we never fitted a heatisink without using heatsink compound to ensure that there was a good heat transfer path from the components to the heatsink.

I was considering doing away with the fibre pad and fitting the washer to the coil using thermally conductive glue to aid heat transfer and help reduce vibration.
Use the same glue when bending laminates in place for the same reasons and a few dots of epoxy to ensure it all stays in place with little or no vibration.
Does Anyone have any better ideas? Are my assumptions wrong?

User avatar
HxPaul
registered user
Posts: 1032
Joined: Fri Dec 06, 2013 1:58 pm
ebay user ID: panhead_5
Main scooter: lambretta Li 150
Location: Halifax,Yorkshire
Contact:

Wed Nov 16, 2016 4:51 pm

When Anthony Tambs fits a new LT coil,before fitting the copper/aluminium washer he makes sure that there is a gap between the washer and laminates because if the washer touches the laminates it can cause heat transfer.

Meds
registered user
Posts: 191
Joined: Tue Jun 23, 2015 2:23 pm
Main scooter: Li125s
Contact:

Wed Nov 16, 2016 5:09 pm

So it sounds like he is protecting the coil from heat generated in the laminate.
My assumptions were completly wrong
Cheers.

User avatar
HxPaul
registered user
Posts: 1032
Joined: Fri Dec 06, 2013 1:58 pm
ebay user ID: panhead_5
Main scooter: lambretta Li 150
Location: Halifax,Yorkshire
Contact:

Thu Nov 17, 2016 1:27 am

HxPaul wrote:When Anthony Tambs fits a new LT coil,before fitting the copper/aluminium washer he makes sure that there is a gap between the washer and laminates because if the washer touches the laminates it can cause heat transfer.
Sorry,I meant to say that the gap is between the washer and the base of the stator plate.

User avatar
coaster
registered user
Posts: 3676
Joined: Wed Jan 07, 2009 12:35 pm
Location: London and Norfolk
Contact:

Thu Nov 17, 2016 11:09 am

If you aren't in a great hurry I would consider getting Anthony Tambs to do the work for you, his workmanship is outstanding and VERY cheap (as in I don't know how he does it for the price). I'm not sure if he comes on here but you will find him on Facebook 8-)

User avatar
corrado
Dealer
Posts: 3192
Joined: Thu Jan 08, 2009 1:12 am
Main scooter: Lambretta GP
Location: Top of Blackpool Tower
Contact:

Fri Nov 25, 2016 5:37 pm


Meds
registered user
Posts: 191
Joined: Tue Jun 23, 2015 2:23 pm
Main scooter: Li125s
Contact:

Sat Nov 26, 2016 5:54 pm

Cheers, Corrado sorted now.
I have just seen Anthony Tams prices for stator refurbished, and some of the other posters were quite right it hardly worth doing it yourself.
The refurb thread shows how good his workmanship is, looks like he covers all of the details to prevent fretting and sealing the cables up right.

Post Reply Previous topicNext topic
  • Information
  • Who is online

    Users browsing this forum: No registered users and 1 guest