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MG TD TF 1500 - Generator/V. Regulator Problem

The Southeast T Register group had an excursion from Atlanta to Anna Ruby Falls in the mountains of northeast Georgia (near Helen) Saturday. I live 137 miles in the other direction from Atlanta so I decidd to not drive to Atlanta and then up to ARF and back (would have been about 200+ miles each way) but instead to go directly and meet them there.

With my sister as navigator we took off at about 9 am on a glorious June morning and started following the yard and a half long back-roads map I'd printed out from Google. We got lost near Westminster SC, trying to get through Clayton GA and near Five Points GA but with perseverance and a little help from an old Garmin we were always able to get back on track.

The TD purred like a kitten all the way and we made it to the Falls in just under 4 hours (target speed 50 mph, average moving speed just under 40 mph). I'd topped up the fuel and oil before leaving and was please to have used only 1/2 qt. of oil and less than 6 gallons of gas.

After a meal of mighty-fine north Georgia bar-b-q we hit the road for home. The TD continued to run great until about 5 miles from the barn when we started hearing a sighing sound and shortly thereafter the ignition light came on BRIGHT red and we smelt just a hint of something not right. I pulled over fearing a broken fanbelt (dumb me- I hadn't carried any spares of anything useful) but a quick check showed the belt to be OK and and both the generator and the waterpump turning (the water temp had stayed at about 185 F all the way even in the high 80s June temps) so I figured the waterpump was OK.

The TD started right back up so I guessed the even if the generator were kaput and not charging I could make the final 5 miles on just battery power. I was right and we pulled up to the barn with still enough battery to restart the TD a couple of times (I had to move some equipment to get the TD into a more convenient bay to do repairs but we were home so we could have pushed it if we had to).

All in all it was a great adventure but now I have to figure out whether the problem is the generator, the V.Regulator or something else. There was a recent thread with detailed instructions for testing both the generator and the V.Regulator and I think I printed out the instructions but I haven't found them yet. Therefore, any hints or suggestions will be GREATLY appreciated.

Safety Fast!!

Jud

'53 TD 25009

ps: this picture does not do justice to these majestic falls.




J K Chapin

Jud - See the article, Testing a Dynamo/Generator and Keep Your Belts Loose in the Other Tech Articles section of my Homepage at: http://homepages.donobi.net/sufuelpumps/ Also check the armature of the generator for excessive side play. If the fan belt is not of the segmented design and/or the belt has been run too tight, there is a good change that the rear bushing in the generator has been worn sufficiently that the armature could be rubbing against the pole pieces in the generator. Cheers - Dave
David DuBois

Dave, thanks for the links. Now I have the instructions - all I need to get started is the guts to dive in and do it. Funny, when I was 25 to 35 and pushing the old TR-4 I'd blindly tackle about anything and figure I could work my way through it by intuition and dumb luck. Now I hesitate for fear of getting in where I can't get out. At least with the generator/regulator issue I can probably replace skill and knowledge with dollars if necessary.

Jud
J K Chapin

Jud - The generator is really a walk in the park, very easy to work on. The regulator is something that I have never had to fuss with, I just had Bob Jeffers turn mine into a solid state unit. Just remember that old age and treachery wins out over youth and skill every time ;-) Cheers - Dave
David DuBois

Thanks for the encouragement. I'm going to tackle it but, WOW!, the first instruction is to disconnect the wires from the generator and connect the two terminals together. That sure feels to me like it's going to short something out but I'll go for it - measure voltage at low RPM from jumpered terminals to ground while slowly increasing RPM to see if I can get 20 volts (My tach doesn't work and I've not found an electronic tach that says it will work on a positive ground system) so I'll just be guessing at the RPMs.

It will probably be later this week before I get to actually start testing but I'll let you know what I find and, again, thanks for the encouragement.

Jud
J K Chapin

VERY! slowly do not go over 20 volts.
If the generator is working correctly it will not take more than about 1,000 RPM if I remember correctly.
Len
Abingdon Performance
Len Fanelli

First check to see whether or not your brushes are making contact with the commutator. Some times as they wear down they hang up.

If so time to renew.

Jim B.
JA Benjamin

Jim B.,

Does that involve removing the brushes? Are they the screwy things at the tach cable end of the generator? Should I remove them and reinsert them in situ? Delving into unknown territory is scary but with y'all's help I'll make it home.

Jud
J K Chapin

I had to look at the WSM. Its been 45 years since I had this problem.
At the tach end of the generator you will find the cover band. It held on to the generator by a single screw.
If you remove it You should be able to see the brushes.
they are held in place by a flat spring, much like a watch main spring.
Wiggle the brushes, push down on the springs and see if the brushed move down on the commutator.
You might be able to so this on the car.
While you might be able to remove the brushes in the car its better to remove the generator.
Only two bolts hold it although you will need to remove the tach gear box and the generator wires.
Remove the battery ground first also.
As I remember Its an easy job to replace the brushes.

I actually, 45 years ago, walked to a parts store across the way and found a suitable replacement. Cant so that today.

Jim B.
JA Benjamin

No clue about the charging. But what a beautiful area! My son and I were up there first week in March. Lots of ice and snow (and closed roads) in the area then. Beautiful hiking and sports car roads a few miles from Unicoi Park. George
George Butz

Jud - You don't need a tach. As Len states, just slowly press down on the accelerator and watch the meter (best to use an old analog meter, but failing that a digital will work - just be ready to back off on the gas if the meter reading goes over 20 volts). Cheers - Dave
David DuBois

OK, I did the tests today. Jumpered the dynamo terminals and measured voltage to ground at low RPM. It rose to 20v by about 1,000 RPM. The next test was with the dynamo wires reconnnected to measure the voltage from the D terminal to ground at low RPM. By about 1,000 RPM it rose to 20v but as the RPMs increased so did the voltage. I accidentally let it rise to about 25 volts but only for a moment. I gave the innards of the VR an inspection and can't see anything broken or obviously wrong but it seems that the second relay (the cut-out relay) must not be opening. At idle the ignition light is out but by about 1,000 RPM it starts coming on and by about 1,500 is bright and steady. I think tht's another indicator that the cut-out relay is not working.

Bob Jeffers, if you are following this you'll have mail soon.

Thanks.

Jud
J K Chapin

The other test is with no connection to the field terminal. The 'D' terminal should give 2.5 - 3.0 volts at maybe 2500 - 3000 revs.This voltage turns the transistors ON. And in effect connects the D AND F terminals. When this happens the voltage shoots up to 14.40 Volts and the regulator is off and running.
Sincerely,
Bob
R. K. Jeffers

Is the field terminal the yellow with green tracer that goes from F to the smaller lug on the bottom of the genreator/ If so, i did the test and got the results you said are correct/necessary.
Jud
J K Chapin

Yes, the yellow wire with green tracer is the field wire.
Bob
R. K. Jeffers

I think my battery is magical. I keep starting and driving (can't outrun summer pop-up thunderstorms but that't another story) with the dynamo out of the loop (both F and D wires disconnected)and it contiues to show about 13 v.
Question: Shouldn't the ammeter be swinging left (toward -) when running with no generator? Mine sits just slightly right of zero.

OK, the thunderstorm - We've had more rain in the past 6 days that in any complete July that I can remember. I wanted to take the TD out because I hadn't been able to drive it for two weeks and I was getting withdrawal sysmptoms. I checks the radar and we were right on the edge of a small cell on the way so I waited. In 5 minutes the clouds burst and I felt smug. That cell passed over in about 15 minutes and I had to wait about 1-1/2 hour for the ground to dry enoug to get the TSD out of the barn.

Afer in intolerable wait (mediated a bit by a well stocked beer fridge) I checked the radar again that nothing showed up for 100 miles. Here's my chance. headed out for my 10 mile loop and to top off the petrol (love Brit lingo - calculated 20.4 mpg for the 270 round trip to Anna Ruby Falls) and she purred even with no dynamo (steady 13v. on the meter).

Pulled in and topped up with E-free gas and got back underway. About a mile down the road remembered that I meant to get some icecream and also noticed some rather ominous clouds. Decided (wrong again) that I could go back, get the icecream and make it back to the barn safely.

Got the icecream and headed out under scattered sprinkles. About a mile down the road and about a mile out the road veered slightly west right into theteeth of it (no hood - no wipers - lots of Rainex that wasn't enough to see through). At 56 mph not too much water getting in but I had to slow down to turn into the road and up the path to the barn (held it in 2nd at about 8-10 and drove like crazy! Got undercover and got soaked. Thankfully, very little watrer got into the car but I was soaled to the waist.

All in a day's fun.

Safety Fast!!

Jud



J K Chapin

Took the ginny off, cleaned it up real pretty like, tested the field resistance (6.3 ohms), inspected the brushes (look pretty good to these untrained eyes and floated nicely on the commutator) replaced the belt with the Gates toothed one and got it all back together. Started it up (miracll battery still going strong) and, with a jumper from F to , got 20 volts at about 1,350 - 1,500 rpm.

I've ordered a new voltage regulator from Moss that I'll install so I can send the one I have to Bob Jeffers for his stealth conversion to solid state. My plan is to install Bob's and keep the Moss one in the tool box to ensure that Bob's doesn't give out on me (sorry Bob but I've found the best insurance against rain is to carry an umbrella).

Thanks to everyone for your hepl.

Jud
J K Chapin

Accidents will happen!!
Bob
R. K. Jeffers

The new voltage gegulator arrived yesterday and I installed it today (only two screws but holding a screwdriver on top while getting a star washer and nut started under the cowl was a challenge).

IT WORKS!!! From the WSM: Disconnect the wires from A and A1 and connect them together; put a voltmeter from D to earth; start it up and increase the rpm. voltage should rise from about none up to about 15.6 and STOP rising and just sit there as RPM continues to increase. The baby passed the test and the ignition light is acting as it should.

I'm dancing a jig and having another beer!!

Thanks for everyone for your help. I had neither the courage nor the skill nor the knowledge to tackle this but you all gave me the confidence to git-r-done!

Jud
J K Chapin

Well, it worked for a couple of weeks but now, with the new regulator from Moss installed, the generator light just glows steady. No variation in brightness with RPM. I'll start the testing all over again but I'm kind of wishing I had one of Bob jeffers' solid state unites to plug in. Did anyone find out if the company is continuing to supple the solid state units? I never had the pleasure of meeting bob or doing business with him but his reputation on this board was superb.

Thanks.

Jud
J K Chapin

Well, I tested the ginny according to Dave DuBois's instructions and according to the WSM before ordering and installing the new control box and the ginny tested good. Installed the new control box and all was woring great. Short drive Sunday and the danged red light came on and stayed on. Tested the darned ginny again tonight and no output. Ordered a new ginny from Moss but they are backed up to late August. Out of frustration I ordered it anyway. Now, is there anybody around here that rebuilds/reconditions ginerators? I think there is but I don't know who it is. Foothills British Car Club had a speaker (a real old country boy) who seemed to know what he was doing but I don't have his name or a way to contact him.

Hap, can you give me a lead?

I'll take the ginny off Saturday and see if wiggling wires and brushes and stuf helps but as someone in another thread sais, I'm not a sparks guy.

Drat!!!

Jud
J K Chapin


Jud.

There is another option to Moss Parts.

The Little British Car Company ....

www.LBCarCo.com.

They have a 140-300 TD/TF Generator.
Price.. $140.00.
( They use the same Part Numbers as Moss. )

Company is in Michigan.


Good Luck.


DrRx.
drcrougeux

DrRX:

Fantastic!! I'll call them tomorrow and see if they have then in stock.

Thanks.

Jud
J K Chapin

Actually, being an impulse kinda guy, I just went to the LBC page and ordered the darned thing. Hope they have one. Thanks.

Jud
J K Chapin

Since the Gen seemed to work before and does not now, try looking at the brushes, If they get hung up the Gen will appear to be bad. they are held down against the commutator wit a spring. Try lifting the spring and wiggling the brushes.

Jim B.

Been there Done that.
JA Benjamin

"There is another option to Moss Parts.
The Little British Car Company ...."

Pretty sure you will find that Jeff is actually a Moss distributer and that is why part #'s and catalog is the same.

That being said, IMHO, Mr. Zorn's service is second to none, and his pricing is generally about 20% lower!

Again, IMHO, even if LBC was 20% more, I would still use them because of the service I have received in the past from Jeff.

I would not trash that old Dynamo/Generator, but rather look for an "old school shop" and have it rebuilt. I say that only because I have no first hand experience with quality of replacement units being sold. Face it...some of the newer stuff just does not hold up as well as the originals.
David Sheward

David S, that's sorta my plan. I hope to get a servicable replacement ginny (From LBC, Moss or whoever) so I can comtinue to drive (even if it doesn't work at all I need it so that the water pump will work) and have the one I'm taking out rebuilt by someone who's good at that sort of thing.

Jud
J K Chapin

DrRx, great advice. The new ginny arrived today, installed this evening and it's putting out a good 14.5 volts. I installed a volt meter and, at first I hooked it to the A terminal of the V. Regulator but I decided all that was showing was the battery voltage. I changed it to the D terminal and now it shows the ginny output. The voltmeter goes from 0 to 14.5 about (exactly?) the same time as the ingition light goes out as revs increase.

I approached the ginny from LBC with fear and trepidation cause it came sans pully and fan and I could envision needing some kind of machine ir technique I don't have to get the pully off the old ginny. Oh! me of little faith.

Pulled the old ginny, spun the pully nut off with a air impact wrench, slipped the pully and fan off, cleaned them up, and slide them right on the new LBC ginny. The end plate castinging on the LBC are not as smooth as the ones on my old ginny and the black body has no stamped markings to indicate model, amp apacity or spin direction but it did come with polarizing instructions (I'd read about doing this here and at other sites but it was nice to have instruction on paper in my sweaty nervous little hands).

Took her for a spin and the voltage on the D terminal held a steady 14.5 at all but low RPMs. Seems that both the new ginny and the new V. Regulator are now working. Got a 100 mile picnic trip ito the mountains coming up in two weeks and I'm raring to go.

Thanks for everyone's help.

Jud
J K Chapin

This thread was discussed between 24/06/2013 and 03/08/2013

MG TD TF 1500 index

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