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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - rotor failure?

Friend's TF1500 suddenly died while driving, was towed home. I went over today and it started immediately. Changed very old points, condensor, fuel clean, pump seems fine. The only thing I noticed was that the rotor appeared fried around the area that the carbon brush contacts. For those who have had the rotor failure problem, what did the rotor look like? Fried? Fell apart? I know it could be other things but just curious. George
George Butz

The only rotor failures I heard of were invisible except for the multimeter, somehow the current wasn't going through (fried inside?).
Willem van der Veer

George,
I had a rotor that fried with about 100 miles on it. Know other defects noted. Replaced with a new one about 1500 miles ago. Complete brake job will be completed this weekend. Thanks for the help!

Don
Don

I had a rotor arm fail after about 50 miles. In my case the insulation between the brass contact and the distributor shaft had broken down causing the voltage coming into the centre contact of the cap to go directly down to earth. The only visible evidence was a small pit mark on the underside of the rotor arm. I know somebody who had the same thing happen three times on his TR4.


John Scragg
52 TD
John Scragg

Re rotor failure

Ye s it happens -same experience here. It was a new rotor.

I and a mobile mechanic tried everything and were on the point of getting the car trailered. I produced an old rotor I had kept int he boot and presto back on the road.

The one that failed was a new one. I took it back and the vendors tested it. It was shorting from the brass top internally straight down to the shaft.

A lot of our parts are now made in outer slobovia.....

This type of experience wa s unheard of at one time but then so were new rubber boots for clutch withdrwal lever which tear when you put them on and turn out to made of somehting like synthetic liquorice..
ken gasmier

George - Rotor failures are common enough the whenever I have something that is not easily isolated, I change the rotor. It is cheap and easy to replace and often a failure is not visible, so I don't waste time trying to analyze what happened. Cheers - Dave
David DuBois

Just out of curiosity, has anyone ever figured out what the life expectancy of a rotor might be, assuming that it passes the 100 or 500 mile marker?
Jim Merz

I have a couple really old ones that still work. Question: The original rotors extended back past center, presumably to counterbalance the brass tip. Seems to me that the current ones with no counterbalance would wobble and wear things out spinning at 2K rpm or so. Any thoughts that our electronic ignitions, wider plug gaps, and resulting much higher spark voltage may be contibuting to the rotor failure thing? George
George Butz

Years ago we were instructed to replace both the rotor and cap at every tune-up since the combination were so inexpensive and it was assumed this would eliminate any partial or pending failure.

The high energy ignition systems of the 70s and 80s (when they still used a disey) employed materials that would function flawlessly for 100,000 miles plus.

Therefore, we know the material and manufacturing technology are available. Can we influence the parts suppliers to provide modern materials and top quality manufacture? I for one would pay several times the price for a rotor that I could count on being nearly failure proof.

What about you guys???

Jim Haskins
1953 MG TD

J. M. Haskins

In reading Jim Haskins comments, the thought about someone using a tractor distributor cap on a TD or TF came to mind. Although I dont remember reading anything specific (old age and memory to match?) about what type, make or year of the tractor, maybe the rotor too would be interchangeable. Anybody know any details?
Jim Merz

Jim ,
That would be me! After several failures of 3rd world replacement parts I took my dizzy cap router points & condenser to a farm tractor supply house. Off the shelf replacement same lucas part #'s use on many 4 cyc older farm tractors. About 1/4 (or less) the cost and much better made! Haven't had a problem in years. Now running pertronix w/ bumble-bee wires. (The replacement wire kits were crap as well) Carry a spare dizzy & points ect but haven't needed it since the tractor parts went on!
Cheers,
David 55 TF1500 #7427
David Sheward

Just wondering about the fellows that have had rotor failures . Have you been running with standard ignition coils and points or are you running some system that may push the voltage higher that normal?
I found that all coils are not created equal. Some have a built in resistor and some dont . The standard TD coil should have an internal resistor in it . The resistor acts like a damper to hold down the curent build up on the coil while the points are closed . If not you could be causeing a high curent draw on the ignition system and early failure .
I have been running with the same rotor , points ,plugs,cap and wires for the last 11000 miles with no problems . I did reset the plugs once but they were not way out . Of course now that I have shot my mouth off it is most certian that I will have a melt down the next time I go out .
A.L. Gerstle

Dave, do you remember, or have info papers that tell you what kind or year of tractor the cap and rotor was intended for? Here in the St Louis area, there are mighty few farm suppliers in the area.
Jim Merz

Folks, take a look inside of your distributor cap. Up in the top you should see a spring-loaded carbon brush that makes contact with the top center of the rotor. Do you see carbon on the inside of your cap? Is the brush showing signs of wear? Is that carbon finding its way into the rotor and causing a leakage path? Check the height of new and old rotors. I think you'll find that some are virtually dragging against the underside of the cap itself and forcing the brush completely into its recess. You'll see circular wear patterns on top of the rotor. The carbon brush has been available as a standard part at Abingdon Spares. It should take lots of use to wear the brush to the point of needing to be replaced.

A.L., the standard TD coil does not have an internal resistor. It gets its 3 +/- ohms of resistance from the primary winding. People installing coils of lower primary resistance are asking for trouble.
Bud Krueger

Jim,
Actually drove the car there in 2001 and pulled the dizzy off. Guy I was with needed the same for his tractor. I think that was a "farmall"? He had tried my dizzy on his tractor and found it & points ect to be the same. I have looked all over for the reciept but can't find it. Wondering if we didn't buy 2 on 1 bill. ( of course I have every othewr reciept for everything I have ever done to this car!) My new cam should be here next week and will check for any numbers soon as I get the TF back from shop. It might still be in the glove box.
Cheers,
David 55 TF1500 #7427
David Sheward

David,
The part number for the lucas distributor cap is DDB111 it also fits the Ford 100E, this explains why it also fits on tractors I was told that it was manufactured by lucas UK until 2 years ago but is no longer available from them. If your farm machine parts supplier has some, I suggest that you buy his whole stock.
John Scragg

DDB111 didn't show up, but this did:

http://www.tractorpartsinc.com/distributor_cap_nca12106a_3373_prd1.htm
gordon lawson - TD 27667

I think Gordon's "link" pretty much shows what I have been saying ....$6.95 or $28.95. 24 "bottles" of savings @ $11.00 per 12 pack! (or on this side of the pond... @ $10.00 > 12pk + $1.00 ice!)
Warm dayz are comming .......
ah, Nice Cold Cheers,
David 55 TF1500 #7427
David Sheward

This thread was discussed between 26/02/2005 and 27/03/2005

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.