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Burning up rotors - plus tech tip to get home!!!

Patton

Jedi Warrior
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Hi guys, sorry for the double post, but I am a little stymied about this, and the more minds helping me figure this out, the better.

Today, I was going to drive the car to a Gulf Coast Healey Club meeting for the first time. I live about as far out as you can live in the suburbs of Houston so I the trip was 25 miles each way.

I thought that I had the car prepared fine for the trip, but a problem reoccurred that I just addressed. After 21 miles of great running, the car sputtered, went about a mile further, and died. I was able to coast to a side road and a very nice guy let me park the car in his driveway and actually drove me the couple of miles left to the meeting.

This acted exactly like it did when the rotor went out last month (see previous posts). I got to the meeting, asked for help. Several people offered, and when the meeting was over, we caravaned to my car. After about 5 minutes, it turned out that I was right, and the brand new rotor had burned through.

We'll a spare was lent to me, the car fired right up, and a member volunteered to follow me home. We got about 15 miles, and the car sputtered, then died. I was able to get it to a funeral home parking lot, and we tried to figure out what to do.

We when to the AutoZone around the corner, and they of course did not have a rotor. We scratched our heads and came up with two ideas. Make a insulating gasket out of the heavy duty rubber insulating tape, and coating the inside of the rotor and the rotor shaft with dielectric grease (probably misspelled, the white type that prevent electric conductivity). We bought the stuff to do both and applied it to the bad rotor. I am happy to say that the car finished the last 10 miles without problems. I will now carry both in the tool kit, and am considering coating the inside of all future rotors as well.

I will say one thing, despite the trouble, it was an adventure, and the car did pull into it driveway under its own power.

The question now, is why is this happening.

Last fall, the day the car was being loaded to come down here, it mysteriously died. The shop replaced all of the ignition parts that they had put on it and it started right up. I am betting that was the rotor as well.

This means that this car has had at least 3, and probably 4 rotors burn up in about 200 miles. I know that there is a bad batch of Lucas rotors out there, but they can't all have been from that batch. My ignition system is stock, what would cause an otherwise strong running car to eat rotors?

I have be told to order the rotors that Carquest sells as the are higher quality than the Lucas, so I am ordering 3 of those (a 60 mile supply the way this is going!!!)

Thanks, especially to Roger, Roger, Wade, Vince, Pat, and everyone else who helped get me home, and Mike for stopping to help on his first meeting run!
Patton
 

Dave Russell

Yoda - R.I.P
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Re: Burning up rotors - plus tech tip to get home!

[ QUOTE ]

I know that there is a bad batch of Lucas rotors out there, but they can't all have been from that batch. My ignition system is stock, what would cause an otherwise strong running car to eat rotors?

I have be told to order the rotors that Carquest sells as the are higher quality than the Lucas, so I am ordering 3 of those (a 60 mile supply the way this is going!!!)
Patton

[/ QUOTE ]
Yes, they could have been all from that batch. I started with a handful of rotors. Tried them one at a time. If the car would run 400 miles with the rotor not failing, it went into the good pile as a spare. One failed soon after installation & one was faulty from the start. I now have two "good" spares.

Interestingly, a 40 year old rotor of unknown brand is still in the car & being used presently. The problem with some of the replacement lucas rotors seems to be that the rivet, used to anchor the brass top to the insulator is set so tight that it causes a microscopic crack in the insulator. My 40 year old rotor has no rivet, The brass is just set into an insulator slot & somehow firmly bonded to the insulator. I have not found a modern replacement rotor with this rivetless construction but am still looking. If the Carquest rotors have no rivet, you have found a good one.

Wider spark plug gaps increase the coil voltage requirements to fire the plugs & put more electrical strain on the rotor insulation.
D
 

Keoke

Great Pumpkin
Country flag
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Hi Patton sorry about the rotor bit,but glad you got to the show. Yes there are some bad rotors out there,However, every since the first one failed on me here is my solution;Using a new rotor, very carefully remove the rivet it prises right out. Next using super glue reset the brass conductor back in its place. Now Mix up a bit of JB Weld and fill the vacant rivet hole with it using a heated wire to make it flow nicely and emulate the former rivet's head. let it cure. /ubbthreads/images/graemlins/nonod.gif-no more shorted rotors-FWIW---Keoke ---P.S. Check the connections at your coil and make sure they are the correct way around.
 

Keoke

Great Pumpkin
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Re: Burning up rotors - plus tech tip to get home!

HI Dave, There is a rivetless rotor it is reportedly unique to the BJ8 cars. It is somewhat larger than the hooked lucas item and it has a straight brass conductor. My last known source for these was Healey Surgeons ,you might give Inan a call and see if they still stock them._FWIW---Keoke /ubbthreads/images/graemlins/cool.gif
 

mbrooks

Senior Member
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Patton,

Glad you got back OK in the end. I was lucky in that my first trip to the meet in the BN2 was uneventful.

I suspect you will be taking the rivets out of all your spare rotors now!!

Mike
 
OP
Patton

Patton

Jedi Warrior
Offline
[ QUOTE ]
P.S. Check the connections at your coil and make sure they are the correct way around.

[/ QUOTE ]

Wow, that is a frustratingly large amount of work for a simple part that should cost $5.00. Since I don't have a stash of old ones, I don't really have a choice.

I'll double check the connections at the coil, as I am pretty sure they are right, so they probably aren't.

Patton
 
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Patton

Patton

Jedi Warrior
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Re: Burning up rotors - plus tech tip to get home!

Is it OK to run the BJ8 rotor on the earlier distributor? I think I noticed earlier today that Moss lists the rotors as being the same.

[ QUOTE ]
HI Dave, There is a rivetless rotor it is reportedly unique to the BJ8 cars. It is somewhat larger than the hooked lucas item and it has a straight brass conductor. My last known source for these was Healey Surgeons ,you might give Inan a call and see if they still stock them._FWIW---Keoke /ubbthreads/images/graemlins/cool.gif

[/ QUOTE ]
 

Keoke

Great Pumpkin
Country flag
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Re: Burning up rotors - plus tech tip to get home!

Hi Patton, /ubbthreads/images/graemlins/smile.gif--Yes you can run the BJ8 rotor in the earlier disrtributors. If you obtain one and install it recheck your eng timing---Keoke P.S. betcha I don't get put on the side of the road for burnt up rotors though /ubbthreads/images/graemlins/grin.gif---BJ8 Rotor Part #1:1.1-046 @ Healey Surgeons /ubbthreads/images/graemlins/nonono.gif--Moss /ubbthreads/images/graemlins/england.gif--OH! costs $6.00, taking out the rivet you can save$3.00 /ubbthreads/images/graemlins/devilgrin.gif
 

Dave Russell

Yoda - R.I.P
Gold
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Re: Burning up rotors - plus tech tip to get home!

[ QUOTE ]

HI Dave, There is a rivetless rotor it is reportedly unique to the BJ8 cars. -Keoke /ubbthreads/images/graemlins/cool.gif

[/ QUOTE ]
Thanks for the info. Don't think it will fit on my four cylinder distributor though. It appears that both the four & six cylinder replacement rotors have problems.

On your epoxy fix - If the rivet has already cracked the insulator, how do you get the epoxy to go into the miscroscopic crack without using a vacuum chamber. If it hasn't cracked the insulator, no need to remove the rivet?
D
 

Keoke

Great Pumpkin
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Re: Burning up rotors - plus tech tip to get home!

HI Dave, The epoxy is an adhesive and also has a relatively high dielectric strength. Slightly heating it causes it to flow and seal off any defects. However, most rotor failures are by dielectric break down between the rivet and the metal locking plate inside . Sometimes, you can limp home by removing the lock plate inside the rotor. The rotor referenced is also applicable to the BN2 cars-Keoke
 

bradal

Jedi Hopeful
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Re: Burning up rotors - plus tech tip to get home!

I have no doubts that there are bad parts, such as rotor buttons, out there as I have run into my share of them over the past 30 years or so of driving Healeys. I would suggest that Patton also check the underside of his distributor cap for the graphite conductor that projects down from inside the cap. That is a spring loaded device that conducts the charge inside the cap. Make sure that conductor is present and free to travel - it's spring loaded. The lack of one could be causing an overcurrent condition that would contribute to the degradation of rotor buttons, especially if they are shoddily constructed in the first place. FWIW AL Bradley
 
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Patton

Patton

Jedi Warrior
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Re: Burning up rotors - plus tech tip to get home!

[ QUOTE ]
I would suggest that Patton also check the underside of his distributor cap for the graphite conductor that projects down from inside the cap. That is a spring loaded device that conducts the charge inside the cap. Make sure that conductor is present and free to travel - it's spring loaded.

[/ QUOTE ]

I checked and it is there, plus it seems to be moving fine. I have a spare cap and will swap it out if the problem reoccurs with the new rotor (when I get one).

Patton
 
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Patton

Patton

Jedi Warrior
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Re: Burning up rotors - plus tech tip to get home!

OK I can report back a little now.

As I said before, in my car, is that the spark is working its way through the casing of the rotor and grounding on the distributor drive. I cannot find a crack (even under a magnifying glass), but I can find what appears to be a tiny hole where the spark has burned through.

I do not know if it is related to the rivet in any way, thought many have reported problems with the rivet.

What I have been told is happening is that there is a problem with the strength of the compound that the arm is built with. This is exaggerated by heat, and as it weakens it can fail by either of the two ways that we are documenting.

UK Healey (https://www.ukhealey.co.uk/) has commissioned a reproduction of the larger arm original style rotor. I ordered 2 of these at a total cost including shipping to the US of $16.38. They arrived today and here are my initial observations.

I'll start this by saying that I do not have any precision instruments to measure this, so everything I say is to be considered approximate.

The ignition rotors from UK Healey are very different than the Lucas Green box rotors that have been the subject of much conversations.

The first, and most noticeable difference is that the arm is longer than the "green box" version.

The radius's from the center of rotation to the edge of the arm are approximally:
7/8" for the "green box" rotor
1-1/16" for the UK Healey rotor

For the distance between the center of the button to the brass plug lead contacts on my NOS Lucas cap is 1-1/8".

There are pictures of the difference at my website Austin-Healeys.com

I would think that the larger gap from the rotor to the contact would increase resistance, and could be causing the spark to seek an easier path, combine that with cheaper constructed insulation, and I think I have found the reason for the burned out rotors.

A worry would arise concerning distributor shaft play. Since this clearance is very small, I would think that a sloppy distributor would cause the arm to hit the distributor.

A couple of other differences are apparent. The new rotor does not have the metal spring on the inside, I do not know if this is important or not.

You will see that the new style rotor also uses a different rivet

The writing on the top of the new style says "remove to oil"

The height of the rotors appears the same

I will send along more information as I play with these, and will eventually place a page on my web site for this. If anyone has a picture of a rotor with a rivet failure, please send it along and I will include it in the final.

I hope this information helps someone.

Patton
 

Dave Russell

Yoda - R.I.P
Gold
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Re: Burning up rotors - plus tech tip to get home!

"UK Healey (https://www.ukhealey.co.uk/) has commissioned a reproduction of the larger arm original style rotor. I ordered 2 of these at a total cost including shipping to the US of $16.38. They arrived today and here are my initial observations."
-----------------
UK Healey is playing with you. It is a standard six cylinder rotor.
------------------
"The ignition rotors from UK Healey are very different than the Lucas Green box rotors that have been the subject of much conversations."
-----------------------
Of course they are different. You have been getting the wrong rotors.
-----------------------
"The first, and most noticeable difference is that the arm is longer than the "green box" version."
-----------------------
It is the standard 6 cylinder Lucas rotor. They are longer.
------------------------
"The radius's from the center of rotation to the edge of the arm are approximally:
7/8" for the "green box" rotor
1-1/16" for the UK Healey rotor"
--------------------
Your green box rotor is for a four cylinder distributor. They are usually shorter by about .210 to .250".
--------------------
"I would think that the larger gap from the rotor to the contact would increase resistance, and could be causing the spark to seek an easier path,"
-----------------------
Yes, it would.
----------------------
"A worry would arise concerning distributor shaft play. Since this clearance is very small, I would think that a sloppy distributor would cause the arm to hit the distributor."
--------------------
This could be a problem. See Andrews comments. My four cyl. 40 year old old rotor has .011" clearance per side, but doesn't hit because the spindle isn't loose or wobbly. A Lucas replacement rotor has .052" clearance per side, so I keep it as an emergency spare. As Andrew said, there is a great variation in replacement rotors.
---------------------
"A couple of other differences are apparent. The new rotor does not have the metal spring on the inside, I do not know if this is important or not.
You will see that the new style rotor also uses a different rivet
The writing on the top of the new style says "remove to oil""
-----------------------
As far as I know, all of the Lucas green box rotors I have gotten, all say remove to oil, & don't have the metal spring. I just don't know why you have been getting what you describe. At least, your new rotor should prevent some problems.
D
 
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Patton

Patton

Jedi Warrior
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Re: Burning up rotors - plus tech tip to get home!

Well, I guess a "nevermind" is in order. It is obvious that every rotor that has been in my car has been incorrect. The strange thing is that they are coming from different sources, and different people ordering them.

The first two were purchased by the PO, and they probably came from Victoria British, as that is where he bought most of his parts.

The third I bought from Realey Healey as part of one of their complete tune up kits. It was prepackaged with a correct distributor cap.

The fourth came from a fellow club member after the car died at the last meeting.

The fifth came from Carquest after it was recommended by another club member as that actually being the correct one.

I never saw the rotor that I got yesterday until then. I wonder how many others are getting this wrong?

Patton
 

Johnny

Darth Vader
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Re: Burning up rotors - plus tech tip to get home!

Could someone tell me why only Healey rotors are going bad? I don't recall hearing any complaints about MG's, TR's etc.
If it's true only Healey rotors are bad, why hasn't Moss, VB, etc. offered a recall of all the bad rotors?
 

Keoke

Great Pumpkin
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Re: Burning up rotors - plus tech tip to get home!

/ubbthreads/images/graemlins/savewave.gifJohny, the reason Healey rotors appear to be the only ones failing is that their owners are using the wrong rotor, the correct rotor does not contain a rivet I posted the source and part number in an earlier reply.Fwiw---Keoke
 
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