Starter backlash...

[boris_thespider]

Is it possible to check the starter backlash with the bellhousing and tranny attached? Thanks...

Mike

[patrickt]

Originally Posted by boris_thespider

Is it possible to check the starter backlash with the bellhousing and tranny attached? Thanks...

Mike

This was originally written by Bob Heacox and is buried deep in the bowels of the ERA site.

After I destroyed one ring gear and after attempting to cut a hole in my bell housing with a hole saw, in extremely tight quarters, I came up with a method of determining, or estimating functional starter pinion to ring gear depth and backlash
As your instructions state, measure ring gear to starter mounting surface. Measure, or better yet you supply in your instructions, distance from face of starter pinion gear to starter mounting surface on starter. In my case the distance from the starter pinion face to the ring gear was about 0.200" which was too much by at least 0.060" Since there were no shims to take out I had to mill at least 0.060" (I milled off 0.100" to gain greater depth and still be within your spec ) The indexing ring had to be removed too since the starter was going to have to be moved towards the crankshaft in order to reduce the gear backlash. I used an end cutting milling bit in a drill press and it worked very well Home shop gearheads like me and other people who buy your starters need to have info like this because machine shops are not always open at midnight the night before a race

Now for checking depth and backlash Cutting a hole in your bellhousing is a *****, to say the least, and you still can't adequately check what you need to check through a hole when the engine is in the car. So, here is what does work very well:


Take the mounting plate off of the starter
Bolt the mounting plate to the engine pushing it as far away from the crankshaft as it will go and against the mounting bolts before the final tightening of the mounting bolts. Re check this when you get to #7.
In order to keep the starter pinion fully extended, the spring fully compressed, and to eliminate, if you handle it carefully, the backlash in the spiral gear, completely compress the spring by pushing the starter pinion gear through the bearing and starter drive gear assembly as far as it will go and then wrap electrical tape around the exposed spiral gear about 20 times.
Blue the starter gear and place the bearing/gear assembly into the starter mounting plate, bolted to the engine, until the bearing is fully seated The starter gear is now positioned in the ring gear as it would be if the starter were turning the engine over during starting
Carefully, at first until you develop a sense of what you are feeling, rotate the engaged starter gear back and forth to feel the backlash and to imprint, in the bluing, how the teeth are contacting, i e Depth of teeth into gear towards crankshaft and depth of gear engagement towards the back of the car
Take the bearing/gear assembly out and inspect the blued gear under good light With a couple of minutes of practice you can determine very accurately how much of the starter gear is engaging the ring gear
Now for checking the backlash Since the starter positioning ring on the starter mounting plate has been removed, during the above mentioned milling to position the starter closer to the crankshaft for more engagement, and so the starter can be moved closer or further away from the ring gear, the starter mounting bolts are now the only things to maintain the position of the starter. So, before checking the backlash, loosen the bolts holding the starter mounting plate enough to move the starter mounting plate as far away from the engine as the bolts will allow and then re-tighten them Clean the bluing off of the starter gear until it is clean and dry and reinsert the starter gear/bearing assembly into the starter mounting plate and gently rotate it back and forth and feel the backlash. A range of 0.010" to 0.030" is fairly easy to develop an estimated feel for. Rotate the engine and check in several crankshaft positions. Elongate the mounting holes in the starter mounting plate, if necessary, to adjust the backlash.
Since I wouldn't trust that the starter would stay in position with only bolt pressure holding it, I drilled one of the holes oversize, pressed a round piece of stock into the hole and redrilled it undersize and then filed it to the exact fit in the correct position
This procedure prevented me from having to remove the engine from the car to set the starter up accurately with any degree of confidence