el torro
Newbie
When my son purchased his 98 c3500 5.7 in October of 2023 it had the infamous starter grind/dying flexplate noise anyone who has ever worked on or owned a SBC is familiar with. I dropped the dust shield and saw the damage was already done. I had him buy a flex plate, all the associated parts that would be needed once it finally ripped the teeth off, and a new rear main seal. Because if you are going to drop the transmission to replace a flex plate on a truck with a completely unknown history what's another $20 and 30 minutes?
Fast forward to May 2024, the bendix won't engage the flex plate without turning the engine with a breaker bar to get to some teeth. I'm not about to try and drop a transmission in my driveway, 20 years ago I would have but I'm retired and I know my skill limits. I have a friend who does work on the weekends at the local GM dealership, he's a great guy and charges extremely reasonable cash prices for stuff like this. Also, it's not my money. The kid was warned that no matter what you drive, you will have some kind of monthly payment. Either you drive something with a monthly payment that is close to new, reliable, and hopefully has a warranty OR you drive something that is paid off, has high mileage, breaks down, and you have to pay all the time to fix something or get something fixed, and figure out how to get to work. Yeah, you might go a few months without a major repair but sooner or later it's going to lay down on you. The exception to the paid-off rule is if you buy it new, take care of it, do the maintenance, and pay it off. He has learned several expensive lessons about listening to his dad when it comes to buying vehicles, I'm pretty sure his wallet is still empty from putting rear breaks on this tank, lol.
Drop the truck off with him on Friday, and by noon it's ready to go. I had him install a brand new (not reman) AC Delco gear reduction starter (part number 337-1022) and new starter bolts (Dorman 678107 - MISTAKE) the truck started great with no grinding!
A week ago my son was getting ready to leave and I heard a grind. The gremlin is back! WTF?!!?!?! I pulled the coil wire, crawled under the truck, and had my son crank it while watching the starter. I could see the starter twist just enough to miss-align with the flex plate. I retorqued the bolts, had him bump it over, and the grinding continued. I ended up dropping the dust shield to get a better look and use some feeler gauges to see how far things were out of spec, and try to figure out what to do.
I tried shimming it and after trial and error I put an 0.18 stack of shim between the starter and engine mounting surface under the exhaust side bolt, I checked tooth engagement by pulling the bendix gear out with a pick. I noticed the bendix gear was not coming out far enough to fully engage with the flex plate gear. It looked like it was about 3mm short. I got the truck back on the road so the kid could get to work, and then started going through the forums here to figure out what went wrong.
I came across Schurkey's comment in this thread talking about the difference in after-market bolts vs GM Genuine 12338064 bolts, so I put GM bolts in my Rockauto cart and then started looking at the specs on starters. I noticed that the DD starter is 2mm longer in the "Mounting Flange to Pinion End" measurement. I had no idea if that would make any difference, but knowing the original starter was a PMGR reman from a parts store, the new Delco starter put on in May was a PMGR, it was grinding teeth off of the flex plate, and eyeball observation of bendix to flexplate engagement looked to be about 3mm short, I decided to give the DD drive a shot.
The new bolts and starter arrived Friday. I put it all in yesterday morning without shims. When I checked the tooth engagement it looked almost perfect. Checking it with a feeler gauge it was right in spec. So far it has started like it's a brand new truck. I'm going to check the torque on the mounting bolts later in the week but I'm pretty sure there isn't going to be an issue.
TL;DR if you are having engagement/grinding starter issues use GM Genuine bolts and a direct drive starter. YMMV but it corrected my problem. So far.
Fast forward to May 2024, the bendix won't engage the flex plate without turning the engine with a breaker bar to get to some teeth. I'm not about to try and drop a transmission in my driveway, 20 years ago I would have but I'm retired and I know my skill limits. I have a friend who does work on the weekends at the local GM dealership, he's a great guy and charges extremely reasonable cash prices for stuff like this. Also, it's not my money. The kid was warned that no matter what you drive, you will have some kind of monthly payment. Either you drive something with a monthly payment that is close to new, reliable, and hopefully has a warranty OR you drive something that is paid off, has high mileage, breaks down, and you have to pay all the time to fix something or get something fixed, and figure out how to get to work. Yeah, you might go a few months without a major repair but sooner or later it's going to lay down on you. The exception to the paid-off rule is if you buy it new, take care of it, do the maintenance, and pay it off. He has learned several expensive lessons about listening to his dad when it comes to buying vehicles, I'm pretty sure his wallet is still empty from putting rear breaks on this tank, lol.
Drop the truck off with him on Friday, and by noon it's ready to go. I had him install a brand new (not reman) AC Delco gear reduction starter (part number 337-1022) and new starter bolts (Dorman 678107 - MISTAKE) the truck started great with no grinding!
A week ago my son was getting ready to leave and I heard a grind. The gremlin is back! WTF?!!?!?! I pulled the coil wire, crawled under the truck, and had my son crank it while watching the starter. I could see the starter twist just enough to miss-align with the flex plate. I retorqued the bolts, had him bump it over, and the grinding continued. I ended up dropping the dust shield to get a better look and use some feeler gauges to see how far things were out of spec, and try to figure out what to do.
I tried shimming it and after trial and error I put an 0.18 stack of shim between the starter and engine mounting surface under the exhaust side bolt, I checked tooth engagement by pulling the bendix gear out with a pick. I noticed the bendix gear was not coming out far enough to fully engage with the flex plate gear. It looked like it was about 3mm short. I got the truck back on the road so the kid could get to work, and then started going through the forums here to figure out what went wrong.
I came across Schurkey's comment in this thread talking about the difference in after-market bolts vs GM Genuine 12338064 bolts, so I put GM bolts in my Rockauto cart and then started looking at the specs on starters. I noticed that the DD starter is 2mm longer in the "Mounting Flange to Pinion End" measurement. I had no idea if that would make any difference, but knowing the original starter was a PMGR reman from a parts store, the new Delco starter put on in May was a PMGR, it was grinding teeth off of the flex plate, and eyeball observation of bendix to flexplate engagement looked to be about 3mm short, I decided to give the DD drive a shot.
The new bolts and starter arrived Friday. I put it all in yesterday morning without shims. When I checked the tooth engagement it looked almost perfect. Checking it with a feeler gauge it was right in spec. So far it has started like it's a brand new truck. I'm going to check the torque on the mounting bolts later in the week but I'm pretty sure there isn't going to be an issue.
TL;DR if you are having engagement/grinding starter issues use GM Genuine bolts and a direct drive starter. YMMV but it corrected my problem. So far.
