Most of the starter end brackets I have found to be bent to varying degrees, so that when an armature has a perfectly straight shaft, it is off-centre through the white metal bearing on the end of the snout. How do you get around/make repairs/adjustments to get this bearing into alignment with the long brass bush and the rear bush in the starter?
Allan from down under.
As you know the Model T starter armature is 15 inches long and even a small amount of misalignment will cause trouble. I have found when rebuilding a starter you have to check everything. Correcting this problem during rebuilding is a combination of things.
First I remove the mounting bracket main bushing and use a gauge I made to check the bracket casting to see if it is bent.
If bent, I set it aside to have the Bendix stop nut running area re-bushed.
Next I straighten the armature shaft so it has only .001-.002 run-out.
I then install the shaft bushing in the bracket and align ream it using a reamer piloted on the new stop nut bushing. At this point the bushing has been machined to accept a oil seal and thrust washer upon assembly.
I use a sealed ball bearing & spacer on the commutator end of the armature.
Finally, I assemble and check the fit and alignment of the armature shaft in the case, cap and bracket and custom fit the thrust washer for a few thousandths end play prior to installing the new field windings. I check the stop nut running area alignment by sliding on the shaft a Bendix drive shaft.
Having done all this I find them to go together very nicely with correct armature end play and armature alignment from cap bearing to the stop nut running area.
Hope this helps.
Ron the Coilman
Ron, how do you straighten the bent housings?
When you line ream the two bushings you then re-establish alignment, regardless of actual bend in the housing. However, how do you maintain perpendicularity of the bearing centerline to the mounting flange face, (on the side that meets the starter field housing)? Certainly, if the snout is bent, and you only re-align the bushings to compensate, you must still be off with respect to the flange.
I have placed the housing on a mandrel and have taken a light facing cut on the side of the flange that locates against the starter housing. In doing so, I have never found the flange to be either perpendicular or flat. However, I have done several, while you have done several hundred. Do you first rebore the bushing diameter in the snout, prior to pressing in the bushing, to re-establish perpendicularity? Just wondering what your thoughts on this are.
Ken & Jerry
A machinist and I developed this procedure to easily and cost effectively save the commonly damaged starter mounting brackets.
The bracket casting damage (actually caused by starting the Model T engine with the spark lever advanced thereby having a kick back) is very limited (the armature shaft really gets clobbered and usually always need straightening), we have never found a bracket cracked or broken. But remember any miss-alignment, however small, is exaggerated by the length of the armature shaft.
We believed trying to straighten the casting would be very time consuming and possibly cause more damage.
We concluded the first machine cut made on this part when new as a raw casting was the starter case mating mounting flange and all other machining operations used this surface as an index. That is not necessarily intuitive until you find the casing main bushing bore was reamed, full of chatter marks and not always precision. Using that bore as an index would not have worked as well. We therefore used the mounting flange/case mating surface (draw filed to get rid of any burrs) as an index using a specially made fixture for the lathe faceplate for boring removing the original Babbitt bushing and installing and boring the Bendix stop nut bushing. As previously shown I use this bushing bore as the index to align ream the main bushing after being pressed into the bracket. This requires a adjustable reamer as the armature shaft at that point is a non-standard size.
This way the mounting flange, pilot hole for the new stop nut bushing, align reamed new stop nut bushing and main bore bushing hole reamed to size are all correctly aligned.
The proof of this process is the final starter assembly where everything fits correctly, the 15 inch long shaft is not in a bind and the Bendix stop nut fits the bushing.
Ron the Coilman
Understood. Makes sense. Thanks for the additional info!
Ron, this topic was part of a long discussion had between father and auto electrician son on a recent interstate trip. He had previously dabbled in straightening the housings, with mixed success. I was of the opinion that the end plate could be chucked in the lathe and the new bendix bushing machined in place.
In the end I think we agreed that a tool turned to register on the internal bore of the bushing hole could be used as an index for the other operations. Your indication that this bore is roughly reamed and is none to accurate means this is not a good idea. Align reaming the new bush an using the newly machined bendix bushing as a register makes good sense.
Using a ball bearing at the commutator end did not come into our deliberations. That too make good sense.
Thank you for sharing your expertise.
Allan from down under.
Additional discussion about the ball bearing installation in the starter brush cap is in order.
Using a ball bearing in the brush cap has been done by Model T mechanics since the 1930's. That implementation included the spacer, a 6201 metric generator bearing, starter shaft turned down and an oil hole drilled into the brush cap bearing boss to facilitate lubrication.
Today you can obtain a good quality 6201 1/2 ID double sealed ball bearing which greatly simplifies the rebuilding process.
Ron the Coilman
Looks like a Very Nice quality Job, Well done !!!