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Trying to find a pilot bearing for the new TKO transmission, but the opening on the rear of my crankshaft seems to be non-standard. Measures about 1.400 or so.......replacement bearing is 1.093. Any thoughts about this??
Thx.
Well, in light of this news, perhaps it's time to rebuild the 455 I've got sitting in the shop. Planned on that for next year, but if I'm gonna have a crank machined, I may as well do the engine upgrade as well. Thanks for the quick reply.
thx.
EDIT: I couldn't find the password for my current screen name when I started this thread so I opened an old account.......LOL! But this is the real me.
Last edited by oletrux; January 18th, 2020 at 11:51 AM.
The OD of a factory Olds pilot bearing (they were bearings, not bushings from the factory) is 1.377. The hole in the crank will be 1.378-1.380. If you are measuring 1.4, that sounds pretty close. Your problem with pilot bearings is that you apparently are only looking a Chevy bearings. American Powertrain has bearings with 1.38 OD.
Thanks guys, I've done a little research today and found the 'conversion' bearing both at Dick Miller and Mondello. The transmission is from American Powertrain so I'll talk with them first thing Monday morning.
Terrific response from this great forum, as usual.
thanks again.
Thanks for the posting. Please keep us informed about what American Powertrain says and/or which pilot bearing adapter you use. Good luck and thanks again.
Thanks guys, I've done a little research today and found the 'conversion' bearing both at Dick Miller and Mondello. The transmission is from American Powertrain so I'll talk with them first thing Monday morning.
Terrific response from this great forum, as usual.
thanks again.
If you post a photo of the back end of your crank, we can tell you immediately if it's drilled or not.
I read somewhere, don't know if its true, all 403's had their cranks drilled for the pilot bearing.... because the 403 was also used in the Pontiac Trans Am. But the Trans Am Firebird did not use the 403 with stick... they used the Pontiac engine in stick cars....
I've also heard that the 403s were drilled for a pilot bearing. I had 3 crankshafts machined to Joe Mondello blueprint in his manual (two 425s and a 455). The 403s I have, have the "steps" but different than the Mondello print. 403s have a larger "snout" area. Picture with multiple crankshafts are the ones machined to Mondello spec's. The engine pic is a 403 crankshaft factory machined same as other 403s I have.
I've also heard that the 403s were drilled for a pilot bearing. I had 3 crankshafts machined to Joe Mondello blueprint in his manual (two 425s and a 455). The 403s I have, have the "steps" but different than the Mondello print. 403s have a larger "snout" area. Picture with multiple crankshafts are the ones machined to Mondello spec's. The engine pic is a 403 crankshaft factory machined same as other 403s I have.
This looks like mine. I believe the bearing should be installed in the center step........
Last edited by oletrux; January 19th, 2020 at 06:16 PM.
I'd measure to make sure there's going to be clearance between the end of the "snout" and the crankshaft before installing the bearing. I think 11/16" drill bit will do the job. I think American Powertrain will be selling more than a few of these bearings in it works.
Well, I just spoke with American Powertrain and ordered the bearings. I inquired about modifying the input shaft or the crankshaft and their solution is a 1/4" spacer between the bellhousing and transmission.........I had them send one of those also and I'll let you know how it works out. Moving the transmission to the rear doesn't seem to be a problem at this point. The Muncie that was installed is a '64 Pontiac long tail, so it's 4" longer than the TKO. Looks like I'll be getting a new driveshaft as well.
I understood that to be true and since I have no further use for it, it will go to the swap meet along with a B/W Super T-10 I no longer need. Perhaps I will recoup some of the TKO's cost.
Well, I just spoke with American Powertrain and ordered the bearings. I inquired about modifying the input shaft or the crankshaft and their solution is a 1/4" spacer between the bellhousing and transmission.........I had them send one of those also and I'll let you know how it works out. Moving the transmission to the rear doesn't seem to be a problem at this point. The Muncie that was installed is a '64 Pontiac long tail, so it's 4" longer than the TKO. Looks like I'll be getting a new driveshaft as well.
The later, 350's & 403s,(that I have) are all like the engine picture I posted. Yes, it looks like the 1.380" A.P. will fit into the 2nd "step" but I don't think the depth to the crankshaft is enough. The 350/403 last step is concave. As I recall, I measured it once and there wasn't enough depth. Once you get the A.P. bearing then you'll be able to figure out the distance you need. I'd be drilling before installing the bearing, error on drilling deeper. Once you Lock-tite the bearing in, that's the final chance. I'd never cut the snout of the input shaft. Jmo. Look at Joe Mondello diagram to see distance you'll need.
Here's the Mondello diagram I used to have some 425/455 crankshafts machined. I gave the machinist a regular pilot bearing from American Powertrain for reference.
So 3 is Oldsmobile, 6 is 1976, M is Lansing Michigan and rest is the last half of the Vin? Still doesn't tell what car it is out of, unless you know the car correct? Was it completely random luck for the machined manual crank like mine?
Last edited by olds 307 and 403; January 20th, 2020 at 04:10 PM.
Dorman makes a pilot bushing that may fit, I used a napa balkamp 615-1131 which may not be available anymore. Depending on the crankshaft the OD may have to be machined down. I put a TKO 500 behind a 403 in my '77 Delta 88 pace car back in 2006 or so. The 403 I used had a drilled crank however the bushing would not fit unless we machined it to 1.337". The hole in my crank was 1.310" I've put about 1000 miles on the engine/transmission since then and I've had no problems. We bought and modified 2 bushings, this is the spare with a tool that my dad machined to install the bushing.
Thanks for the info. Here's the "old school" pilot bearings I got from American Powertrain. I gave them to the machinist before he machined my crankshafts to Joe Mondello diagram, just so their wouldn't be a "failure to communicate."
Thanks again for everyone's information.
I don't think the American Powertrain 1.380 roller bearing will work. (To mjrj; is the number you gave for the hole correct at 1.310"?) I went to a indoor swap meet in Medina,Ohio on Sunday so I stopped at Summit Racing and bought a similar Centerforce pilot bearing to try it. Neither the roller bearing or the American Powertrain bushing type pilot bearing will work in the 403, I tried. I'm unable to get an exact Id of the crankshaft, the second step. https://www.summitracing.com/parts/ctf-43002/
Dorman makes a pilot bushing that may fit, I used a napa balkamp 615-1131 which may not be available anymore. Depending on the crankshaft the OD may have to be machined down. I put a TKO 500 behind a 403 in my '77 Delta 88 pace car back in 2006 or so. The 403 I used had a drilled crank however the bushing would not fit unless we machined it to 1.337". The hole in my crank was 1.310" I've put about 1000 miles on the engine/transmission since then and I've had no problems. We bought and modified 2 bushings, this is the spare with a tool that my dad machined to install the bushing.
Originally Posted by Kennybill
I don't think the American Powertrain 1.380 roller bearing will work. (To mjrj; is the number you gave for the hole correct at 1.310"?) I went to a indoor swap meet in Medina,Ohio on Sunday so I stopped at Summit Racing and bought a similar Centerforce pilot bearing to try it. Neither the roller bearing or the American Powertrain bushing type pilot bearing will work in the 403, I tried. I'm unable to get an exact Id of the crankshaft, the second step. https://www.summitracing.com/parts/ctf-43002/
It sounds like the crank was drilled to 1.310" and the pilot bushing (bronze bushing) was machined down to 1.310". The pilot BEARING (ball bearing) would be to large ! The bronze bushing can easily be machined down to whatever size hole you make it. The pilot (ball) BEARING is not easily machined and also needs a certain size hole to be inserted into.
The hole in my 403's crankshaft measured out at 1.310". We machined the bushing down from the original OD of 1.379" to 1.337". The register where the bushing rides was cleaned and after the bushing installed checked for concentricity, and was found to be ok at that time. I've put about 1000 miles on it since installation in 2006-2007 with the last 800 or so being since 2018 when I finally swapped out the 2.41s for 3.73s, and that includes 4 passes at Tuscon dragway during zip tie drags 2 weeks ago. Its worked so far. I do plan on taking the current engine out and performing some upgrades after tax time (roller cam, 5 main halo girdle and edelbrock heads) so we'll see how the bushing has held up then. I also want to replace the cast crank with something stronger, and I'm thinking one of those stroker cranks might be nice...
Bought the bearings from American Powertrain. Measured the bushing that was previously installed, and had a local machine shop grind the new bearings down to the same size: 1.361"
Installed with red locktite and that part of the job is done. If I can afford to build the 455 for the car next year, I know another thing to watch out for!. If the 403 hangs in there for awhile longer, I have a spare pilot bearing.
Thanks for all the info guys. This site and those on it 'rock'.
More Questions, inquiring minds want to know. (:•》
Which "bearing" did you get from American Powertrain? The roller bearing 1.380" OD (Ford with GM Transmission, I think?) or the 0-127-007 bronze pilot bushing that I pictured in previous post? I half-***'d a piece of metal to get a decent measurement of the ID of a 403 and also got 1.361. Curious on which type you got machined. Thanks for your replies.
As far as I could tell he had a lathe with a carbide cutter. I think he turned a suitable mandrile then chucked it up between two slightly smaller washers and spun it up. Commenced cutting the outer race until he got the diameter needed................
Last edited by oletrux; February 4th, 2020 at 11:07 AM.
January 18th, 2020, 09:01 AM
