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TR2/3/3A TR3/4 Dynamo Bolt

Geo Hahn

Yoda
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Can someone tell me the size of the bolt that attaches the lower front of the generator? Possibly part 19b in this illustration:

TRI-001.gif


I recall it is best to use a bolt with a shank. I'm working more or less by feel so asking is easier than trial & error. Thanks!
 
George,

I believe that's a 5/16 x 24NF bolt. Threads start at the face
and run in at least 1" on mine.

By the way did you ever get that positive ground, auto flashing unit for your brake light installed. Mine works like a charm, really catches the eye.
 
Thanks, it was mainly the threads I was concerned about... didn't want to wrench on a bolt of the wrong thread. I had a 1 3/8" long with about a 1/2" shank in that size and that worked. Going with blue locktite and a lock washer.

The last three 500+ mile trips have each shaken off a different generator bolt. The first one was my fault as I did not have the lock tab in place on the engine-to-mounting bracket bolt. The other 2 just worked loose I suppose. I do not run my belt very tight so maybe I get excess vibration.

I have the flashing blinkers gizmo on both cars. Works well but I can see that the effect would be much more pronounced with LEDs instead of incandescents.
 
Glad to help on the thread, God bless locktite.

On the blinker, I actually did mount a short LED light bar just ahead of my gas filler.
Sure beats that factory center single stop light.
 
Bit of a hassle to find but grade #8 bolts should be used on the generator as the vibration can be quite harsh.Also when you have a generator off,take it apart and find the fatal flaw the monkeys left inside.Often the front bearing is loose or not lubed,once had one with NO bushing pressed into the rear housing....none.
MD(mad dog)
 
On the TR3 racecar, I drilled the head and saftied the generator bolt that sets the belt adjustment after it loosened and cost me a belt.
 
Good idea!

Probably too late to do any good now, but I suggest inspecting the threads in the pedestal (#19 above). They are sometimes waddled out until they won't hold, even though the bolt seems to come tight. I put a Helicoil in mine. I also make it a point to double-check the bolt at every tune-up.

If the holes in the butter-soft aluminum are worn, they can be drilled (or reamed) and sleeved with thin-wall brass tubing, available at any hobby shop.
 
Weird timing, after a drive yesterday afternoon I noticed the my accessory belt was loose and wiggled the generator. The pedestal was loose as well as the front bolt was missing. Luckily the two other mounting bolts were holding 100%, I had just done a fast highway stretch.

My threads were stripped, I went to home depot for a tap and tapped for a larger 3/8" grade 8 bolt. That pedestal is very beefy.

It is probably worth taking off the pedestal and closely inspecting the threads, I know I have check/tightened that bolt in the past but obviously the threads were barely holding. Taking the horn off, I was able to easily get the generator out.
 
Now about that pedestal (part 19)... was the guy who designed the generator not on speaking terms with the guy who designed the bracket?
 
Yeah, you could put it that way. Remember the generator is a "one size fits all" made by Lucas, while the engine is a "one size fits all" made by Standard. They were emphatically not designed for each other.

BTW, the nut that holds the pedestal to the front plate is a Nyloc, and hence should be replaced after a fairly small number of off/on cycles or if it works loose. If a new one works loose, there are stronger metal-metal locknuts available.
 
Aloha Geo,

I have had a similar problem with my TR3A after noticing that the front generator mounting bolt was loose and the replacement bolt wouldn't snug up. I also noticed the generator pulley was not aligned with the other pulleys. After taking out the generator I found several problems, the mounting hole on the front of the generator was enlarged and oval, the front and rear mounting bolts were eroded smaller in diameter, the threads in the front mounting pedestal were so worn the bolt could not be tightened, and the holes in the generator mounting bracket were also worm. The front plate hole for the mounting pedestal was enlarged and oval plus a depression in the surface of the plate was worn down by the pedestal toward the center of the engine. I've corrected the oval holes by welding and drilling/reaming holes, purchased a new generator mount bracket, filled the face plate depression by welding and grinding and replace all nuts, bolts and lock washers.

My point is, when something in this generator mounting scheme loosens up, it cascades into a problem in another part of the mounting and eventual affect all parts of it.
 
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