24x Reluctor Wheel Issue. LSA Block/Crank
 

So I'm reusing my old LSA block/crank (out of a CTS V getting a new 416) and putting it into my c5. I got my machine shop to swap the 58x for a OEM 24x. Today I go to torque my ARP studs down and checked some tolerances on the crank. Everything checked out good .005 end play but the reluctor wheel has up to .038 in one spot. It's generally around .02 everywhere. The 24x is welded on in 2 spots to the crank. It is super close to the weight of the crank shaft (0 runout there) and the runout is worse on the opposite side where there is no counter weight if that makes since. What would you guys recommend I do? Obviously don't want to put the motor back in and have issues but since it is welded on might be a PITA to fix right. Appreciate the help.

Somewhere Lance aka Pantera EFI who was involved in the invention of the 58x system said .002 is good and over .010 can be an issue but it's less critical on a 24x system. I don't know the exact spec for 24x reluctor run out. I've read for 24x was .010 factory spec and one of the crank companies say .020 acceptable.

I think at .038 it needs to be fixed. I wouldn't try to run it because it will be a pain in the ass to pull and fix if it has issues.

A new billet 24x reluctor might be a good solution.

The factory reluctor is sort of thin and welding might cause a little distortion. I don't think they are welded by GM. A tiny burr on the crank might have been the issue.
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​​​​​Someone else with actual experience and knowledge can probably say for sure.


Did the shop use the Goodson tool?

Goodson tool - alignment reluctor
https://cimg1.ibsrv.net/gimg/ls1tech...ad5d275573.png


Threads about reluctor runout.

24x reluctor run out LS3

Yellow Bullet
24x issues reluctor runout

Found where Lance talked about the 58x and comments on what crank manufacturers said on runout per forum members.
Reluctor runout

Thank you for the threads. I found all those yesterday googling around and the 24x not being as important was interesting. I also read welding it on is desirable to prevent it from moving.

I was curious to others options in case the shop tells me to run it as is. That post from Lance was definitely interesting. I can easily see the runout with my eye. Will post up here the solution I come to either way.

I am not sure if they used the goodson tool or not. I will ask tomorrow.

Thanks!

You can tap on it to straighten it out.

I ran into the same issue and I'm pretty picky on the runout. So I just put a dial indicator on it and tapped the "high spots" and got it within .005". No issues after 7K miles.

I have seen quite a few of the 24X crankshaft reluctors have runout in the 0.0300" range and be far and away from creating a problem.

I have seen others with only 0.0200" and have a problem... It is a mixed bag unfortunately... Both those numbers are truly excessive anyway.

Aim for ten or less for reliability.

I unfortunately did not have the opportunity to see much of the Gen 3 24X crankshaft trigger system during my time at GM/ Delphi... I do not have the hard specs on this system, but I know what I have built or repaired and sold.

My time as an Engineer (Repair Div. NOT Design Div. like others here) was spent on the Gen 4 58X system, and there is absolutely no room for error compared to the 24X system.

0.0020" of runout would be an ideal maximum... I rarely see this spec with mass produced parts unfortunately.

I do not sell a 58X crankshaft that has more than 0.0040" reluctor runout, and I will not build an engine with such a crankshaft either.

I have always aimed for less runout, however on the 24X parts anything under 0.0120" goes out the door to a customer.

The 24X system has the reluctor teeth spaced further apart compared to a 58X reluctor. This leaves more room for variance in the runout...


https://cimg8.ibsrv.net/gimg/ls1tech...d541b7586a.jpg

On the 58X with the teeth so much closer together, runout is perceived with far less movement when the teeth are closer together. Problems usually arise with 0.0100" or more of runout.

The single large gap of teeth on the 58X reluctor is a big part of why runout must be far less. In the most simple of terms... Should that first tooth for example be missed do to excessive runout, than the ECM will read an incorrect crankshaft position/ speed.

Again I have seen over 0.0300" runout operate perfectly fine on the 24X system. However that is not what you should want.

Okay, according to an old friend at GM TAC that was involved with the 24X system, he says the original GM spec was 0.0100" (that is Ten Thousandths). Sloppy Sloppy Sloppy... When we see measurements triple that figure.

Thank you guys for all the information! I used a couple interior plastic trim tools wedged between the cap and wheel to get it to about .015 during pre assembly. I will likely try to get it closer to .010 when I go to do the final assembly. What is making it difficult for me is the ring is welded to the crank in two spots. Assume the machine shop did that to keep it from moving on the crank hub? Fingers crossed I have no issue.