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MG TD TF 1500 - Didtributor gear sheared off

XPAG Engine

The drive gear on my DKY4A distributor came off the shaft. Looks like the locking pin sheared off. Has this happened to anyone else? I fished it all the way to the distributor mounting hole probably 20 times with a magnet but it falls off at the bottom of the opening. My inclination is to leave it. I have a magnetic drain plug so the pin should eventually end up there. What do you think? BTW, if you are wondering if the drive gear will fit through the oil drain hole...it won't.

Tim
Timothy Burchfield

That is quite a big piece of metal to get picked up and put through the side of the crankcase. There is not much clearance between the baffle plate and the crank.
Have you tried a hooked piece of wire with the magnet.
I fitted a dizzy without checking it had a solid pin rather than a roll pin, it sheared so I was in the same boat as you. I took off the sump to get the bits out.
I tried to load a pic of the shame of being hauled onto a flatbed but it was too big
Ray TF2884
Ray Lee

Yes, it happened on my Y-Type once. I was able to fish the gear out of the oil pan with a magnet. Maybe try a stronger one? I didn't see how it would hurt anything being in there, but I didn't want to buy a new one nor worry about it whenever I drove the car. The pins were still in the gear and dizzy shaft so I didn't have to get those out on their own. You can probably drain the oil and get the pin pieces out through the drain hole.

This is precisely why I now carry a complete distributor as a spare instead of just ignition pieces. If you're driving around town no big deal, but if this happens far from home then you're absolutely stuck. If I need ignition parts, I can take them out of the spare distributor. And on a TC the complete unit fits inside the battery box with cap and wires attached, along with a coil, a fuel hose, an upper radiator hose and a couple bottles of oil.
Steve Simmons

Bummer Tim. Is the use of a roll pin problematic? Ray's concerns about the potential for serious damage seem very sensible. My rebuilt dizzy has a drive gear secured with a roll pin. Should this be replaced? If so where do I find a suitable pin? How is a solid pin secured? Is it peened over at each end? Cheers
Peter TD 5801
P Hehir

Peter, I believe it was a roll pin. I'll never use another one.

After four hours I was able to fish it out with a flexible light, a strong magnet and a flexible claw grip. Every time it fell off the magnet or the grip it fell on top of the tray in the oil pan. Then it took several minutes to move it so it would fall into the pan. The last time I got lucky and the grip caught the gear in the proper orientation to come out of the distributor mounting hole. I'd like to apologize to my neighbors, my town and the midwest United states for the language they no doubt heard me using.


Tim
Timothy Burchfield


Tim, I wonder what cause the pin to shear? I can't believe the normal rotational force of the distributer shaft sheared a roll pin. Those things are pretty tough!

I would do a little further research to determine what possibly locked up and caused the pin to shear. Recommend you look under the points plate to check the advance mechanism parts?
Richard Cameron

Richard, thanks, I will.

Tim
Timothy Burchfield


Tim, I assume you have an early engine since you mention the DKY4a distributer in your posting.

Check to confirm you have the correct #P/N distributer for your engine and the 1/8" steel spacer as needed. This is to confirm your cam gear and distributer gear are running at the correct mesh relationship.
Richard Cameron

Richard, where does the spacer go, between the gear and the body? My distributor is 40162e. According to the Lucas parts catalog that is the correct distributor for my 51 TD.

Tim
Timothy Burchfield

The spacer is to raise the distributor 1/8" out of the block, so it goes under the distributor where the clamp is. TCs used a microadjuster that the TD does not have, so there is a 1/8" difference to be made up. See here for info: http://www.mg-tabc.org/library/distributor.htm

The pin will shear if the advance mechanism locks up. It's possible that this is a safety design, to prevent damage to the cam and distributor should it lock solid. So install a stronger pin at your own peril! Similar to the tach gear reduction box being a sacrificial component to save an expensive chronometric instrument.
Steve Simmons

The spacer Ring is on main housing shaft


Richard Cameron

regarding the carrying of spares..that is what AAA, cell phones, a tool kit and fedex is for... Regards, Tom
tm peterson

... can't believe my ageing eyeballs. I was going to order a new fluted tap, but had trouble finding the correct ½" X 16 BSF on Amazon. Something twigged and I was provoked to check a box of taps & dies I haven't looked at in 40 years ... and bingo!! I have two - a tapered starter and a straight tap and both in good shape.

Just had to share my good fortune with somebody!

Gord Clark
Rockburn, Qué.
Gord Clark

Richard and Steve, I have 4 DKY4A distributors and none of them have the spacer ring. Can it be purchased from the usual suppliers. I don't see it on any of the DKY4A distributor diagrams available on the net.

Tim
Timothy Burchfield

Richard and Steve, the Lucas parts catalog doesn't show a spacer in the expanded parts list. Is the spacer designed to fix a problem and is just an off the shelf item? My distributor is correct for my engine and the clamp is the correct one for my model of distributor. I'm wondering why Lucas didn't specify a spacer if it is needed in a stock configuration.

Tim
Timothy Burchfield

I share Rich Cameron's surprise at a sheared roll pin. I would really try to figure out why it sheared, as that is not normal. If the pin were too small it would just fall out, and if the pin were too large it would not fit. Very little power is needed to spin a distributor; there is very little resistance.

So I'm puzzled, and feel there must be more to the story.

Tom Lange
MGT Repair
t lange

There seems to be some confusion about the spacer.
In fact it is difficult to get it wrong. Here's how to check. With the distributor, the clamp and the shoulder bolt, correctly in place but loose. You fully tighten the shoulder bolt,(The shoulder should then be hard against the engine block) you should still be able to rotate the distributor. If this is not the case, the circular slot on the distributor shaft does not align with the centre line of the shoulder bolt, thus preventing the distributor from rotating, making it impossible to time the engine. Hope this is clear.

John
J Scragg

Tom, the hole in the distributor shaft appears to be too big (oblong). I'm thinking that the pin came out of the hole and didn't shear. If it sheared I would expect to find the remains of the pin in the distributor shaft.

John, with the shoulder bolt tightened against the block but the clamp lose I can rotate the distributor. If I tighten the clamping plate the distributor will not rotate. I do not have the spacer shown above. This is the clamp I have.

Tim




Timothy Burchfield

Tim,

That is the correct clamp. If the distributor is free to rotate, then you don't need a spacer ring. To be really sure there is one more thing to check.
Verify that the clamp is resting against engine block and the distributor body is resting on the clamp. There should be no gaps between these parts.

John
J Scragg

In the Lucas manual it says to peen the end of the pin to fix. Although spiral roll pin were around it the fifties I think "c" lock pins were later. I do not remember them when I trained in the fifties.
Ray TF 2884
Ray Lee

John, the distributor does seat all the way down to the clamp. Thanks for your input.

Ray, I didn't put the pin in the distributor so I don't know how it was affixed (peened or not). I picked it out of the parts bin because the one in the car was pumping up oil into the distributor body. I did fit a roll pin to another distributor so I initially thought that was the one in the car but it wasn't. Thanks for the info on peening.

Tim
Timothy Burchfield

The original pin was neither a C-pin nor a roll pin, but a solid pin, peened over on both ends. People use roll-pins because they are more readily available.

So the pin didn't fail, but the shaft was defective causing the pin to fall out? Makes much more sense. Sounds like you need another distributor shaft. Maybe have Jeff Schlemmer rebuild a distributor to suit?

Tom Lange
MGT Repair
t lange

Tom, yeah, I inspected the weights, gear, cam gear and the seating of the distributor in the body. The only logical explanation is that the pin came out. I hope to find it stuck on your magnetic drain plug next oil change. I'm getting a 123Ignition distributor next week. I'll let you know how it works out.

Tim
Timothy Burchfield

The spacer isn't a Lucas item as far as I know. It was installed to correct the reach of the distributor body in the XPAG for TD (for which the micro-adjuster had been deleted) and therefore align the distributor gear with the cam gear. The micro-adjuster on the TC was 1/4" thick and the TD pinch clamp was 1/8", so they added the spacer to make up the difference.

I don't recall for sure, but if you leave the spacer out I think the distributor will still go all the way in. But, the gear will not be aligned and will wear or possibly have slop in it. If the usual parts suppliers don't sell a spacer, just go to any industrial supply and get a 1/8" spacer with the correct ID. It isn't anything special. In a pinch, you could double up on pinch clamps, which are 1/8" thick.
Steve Simmons

I would make one recommendation. Get a flexible scope for you phone and look at the Cam gear. I had a distributor gear come off. It damaged the cam gear and I had to replace the cam.
Bruce Cunha

Steve, can you give me a source from MG or Lucas describing the need for and the installation of the spacer? I searched Work Shop Manuals (I have three different ones) and Lucas reference material and I can not find any mention of the spacer. One would think if not having the sacer would cause the problems you describe it would be mentioned somewhere in official documentation. Sorry to sound like a doubting Thomas but I find it odd that something that could lead to a possible expensive failure is not addressed by MG or Lucas.

I will note that the 40162 distributor is not listed for the TC in the Lucas catalog. Distributor 40048A/F is listed from 1946 until 1949. I wonder if the shaft of the later 40162 was changed from the 40048A to accommodate the thinner mounting plate? It would be great if someone with a 40048AF distributor could measure the length of the distributor shaft to determine if it had changed on the 40162 model.

Regards

Tim
Timothy Burchfield

Tim, I have more than one TD also (1951 and 1952). All have the spacer, but I can't confirm they were factory provided because my cars were all previously owned.


John Scragg describes a good way to make sure the spigot bolt(shoulder bolt) registers in the circular cut groove in the distributer case shaft slot.

Abingdon Spares lists the ring as a shim in their on-line catalog.
Richard Cameron

Richard, I saw the spacer on the AS site. At least I'll know wher to get one if needed. I still would like to know if the distributor that came on the TC wa any different than the one that came on the TD (40048 vs 40162). I'd also like to confirm that the idea of adding the spacer came from MG or Lucas. One interesting note, the Lucas catalog states that the drive gear for both distributors above was supplied by the car manufacturer. I wonder if the drive gear for the two distributors were different. Ony a retiree like myself could waste so much time on such an arcane matter :-)

Tim
Timothy Burchfield

Rob at British Vacuum Unit has lots of T series distributor knowledge and cores to build you a unit. Very helpful and friendly.

Recently built me a points plate with everything included, a work of art.

Peter
P G Gilvarry

Thank you Peter, appreciate the information.

Tim
Timothy Burchfield

The gears were the same. They drive off the camshaft, and no change was made in this area during the XPAG production run other than cam profile. The spacer was undoubtedly an M.G. addition so they could continue to use the same distributor but delete the expensive micro-adjuster. Lucas would have been happy to sell them whatever new distributor they wanted, but M.G. probably had huge bins of distributors to use up before changing to one with correct dimensions for use without the adjuster. (D2A4)
Steve Simmons

This thread was discussed between 27/08/2019 and 30/08/2019

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