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Another ls to NV4500 question

kyle.rj133

kyle.rj133

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After lots of reading about this swap I odered a RAM 1550 flywheel a few years back when i was getting my 5.3l built. come to find out everyone is getting the RAM 1550X flywheel wchich the .400" thicker. Does anyone know if my Ram 1550 flywheel will work or do i need to go buy the RAM 1550x? Im hoping I can use my flywheel I already purchased. I got it balanced to my rotating assembly when I had my motor built. and on the pilot bearing do I use the ls7 or the Ls2 and lastly any recommendations for a clutch for 600-650hp preferably a non dual disk if possible
 
Subscribed, because I have been reading some on this as well.
Advanced adapters sells an adjustable pivot ball stud which might help, I don't know.
 
You can just use a flywheel spacer and longer bolts to take up the extra .400".
 
Chevy305 said:
You can just use a flywheel spacer and longer bolts to take up the extra .400".
Click to expand...

interesting. I had a problem on mine (not an LS) where the flywheel and pivot stud were about .4” off and prevented me from getting good clutch disengagement. I had to get a taller pivot ball stud made to fix it. I wonder if different flywheel thickness are made for the standard bbc/sbc?
 
Chevy305 said:
You can just use a flywheel spacer and longer bolts to take up the extra .400".
Click to expand...
The information that I found said that there weren't bolts of the appropriate length to go through the spacer and the manual trans flywheel which gave decent thread engagement. Not sure though as I haven't actually tried it.
If you have some bolt information, that would be cool!
 
How about buying a flywheel for a GMT800 truck that came with a manual trans? Just a silly thought to avoid paying the BS pricing for so called "conversion" flywheels.
GMT800's were available with a nv4500 in the 2500's behind a 6.0L and a nv3500 in the 1500's behind a 4.8L. And since they were available that way any stock replacement flywheel for one of those trucks would work when you are using an nv4500 with an LS engine into squarebody.

Napa has a Luk flywheel part #NCF 88387 for $294, shop around for a better price.
 
@ZooMad75 , what year truck went away from the extended crankshaft flange? I read that the early ones had the crank flange longer than the rest of the engines.
 
6872xtc said:
@ZooMad75 , what year truck went away from the extended crankshaft flange? I read that the early ones had the crank flange longer than the rest of the engines.
Click to expand...
I'm not sure. But I can open up the GM parts catalog pretty quick and compare the part numbers. Let me go look.
 
6872xtc said:
@ZooMad75 , what year truck went away from the extended crankshaft flange? I read that the early ones had the crank flange longer than the rest of the engines.
Click to expand...

also intrested. I thought that I bought a stock size flywheel but then I was doing reading and seen the .400” thicker one it made me start questioning..
 
Last edited:
Reviewing the details from the catalog shows the '99 and '00 4.8 and 6.0 engines used different flywheels. The '01 and up 4.8 and 6.0 used the same part number. The early part numbers for either engine are both discontinued. The later part number is still a good number though.

What I can't tell is what the difference is between the early and later part numbers. Could be the crank flange, could be something else. The catalog does not go into detail of the changes.

Here are the numbers..

12561757 1999 2500 6.0 flywheel
12561757 2000 2500
12561680 2001 2500
12561680 2002 2500
12561680 2003 2500
12561680 2004 2500
12561680 2005 2500
12561680 2006 2500

12561755 1999 1500 4.8 flywheel.
12561755 2000 1500
12561680 2001 1500
12561680 2002 1500
12561680 2003 1500
12561680 2004 1500
12561680 2005 1500
12561680 2006 1500
 
ZooMad75 said:
Reviewing the details from the catalog shows the '99 and '00 4.8 and 6.0 engines used different flywheels. The '01 and up 4.8 and 6.0 used the same part number. The early part numbers for either engine are both discontinued. The later part number is still a good number though.

What I can't tell is what the difference is between the early and later part numbers. Could be the crank flange, could be something else. The catalog does not go into detail of the changes.

Here are the numbers..

12561757 1999 2500 6.0 flywheel
12561757 2000 2500
12561680 2001 2500
12561680 2002 2500
12561680 2003 2500
12561680 2004 2500
12561680 2005 2500
12561680 2006 2500

12561755 1999 1500 4.8 flywheel.
12561755 2000 1500
12561680 2001 1500
12561680 2002 1500
12561680 2003 1500
12561680 2004 1500
12561680 2005 1500
12561680 2006 1500
Click to expand...

hmm maybe I will try to find a stock flywheel and compare it to my current flywheel. I’m kind of thinking the difference in thickness is in the crank flange
 
i’m curious how this unfolds, i’m also building a 600-650hp LQ4, nv4500 combo. i’ll post anything i run across
 
shock88 said:
i’m curious how this unfolds, i’m also building a 600-650hp LQ4, nv4500 combo. i’ll post anything i run across
Click to expand...

Im just going to go ahead and run my RAM 1550 flywheel. I ordered a 11" sbc clutch for it. From what i have read, you will have to use the ls2/ls7 pilot bearing(PN:12557583) cause the snout of the crank is .400" further away and needs to be supported, and possibly a different pivot ball for the clutch or a different throwout bearing(novac adjustable or 1697c) to make up the .400". The bad part about not running a thicker flywheel like the RAM 1550x or a stock late model flywheel is that the clutch might not ride fully on the splines of the input shaft and your clutch fork geometry could be off. thats why you need the .400" thicker flywheel. Some people have ran the .400" spacer but also some have ran into starter alignment issues.

Years, Liters, Casting #, Trans Flange Thickness.
* 1999-2000 4.8L 312 V-8 M/T 1.250" thick flange
* 1999-2000 6.0L 215 V-8 1.250 thick flange
* 1999-2007 4.8L 482 V-8 A/T .857" Flange
* 2001-2007 4.8L 482 V-8 M/T .857" flange
* 1999-2007 5.3L 216 V-8 A/T .857" flange
* 1997-2004 5.7L 216 V-8 .857" flange
* 2001-2007 6.0L 216 V-8 .857" flange

Another guy on a different forum ran the exact same setup that im going to run with zero issues for over 70k miles. and hes making about 400 whp. I will have to check the clutch alignment on the splines and see if im happy with it, if not i will buy the thicker flywheel and be done with this B.S.
 
kylerj133 said:
Im just going to go ahead and run my RAM 1550 flywheel. I ordered a 11" sbc clutch for it. From what i have read, you will have to use the ls2/ls7 pilot bearing(PN:12557583) cause the snout of the crank is .400" further away and needs to be supported, and possibly a different pivot ball for the clutch or a different throwout bearing(novac adjustable or 1697c) to make up the .400". The bad part about not running a thicker flywheel like the RAM 1550x or a stock late model flywheel is that the clutch might not ride fully on the splines of the input shaft and your clutch fork geometry could be off. thats why you need the .400" thicker flywheel. Some people have ran the .400" spacer but also some have ran into starter alignment issues.

Years, Liters, Casting #, Trans Flange Thickness.
* 1999-2000 4.8L 312 V-8 M/T 1.250" thick flange
* 1999-2000 6.0L 215 V-8 1.250 thick flange
* 1999-2007 4.8L 482 V-8 A/T .857" Flange
* 2001-2007 4.8L 482 V-8 M/T .857" flange
* 1999-2007 5.3L 216 V-8 A/T .857" flange
* 1997-2004 5.7L 216 V-8 .857" flange
* 2001-2007 6.0L 216 V-8 .857" flange

Another guy on a different forum ran the exact same setup that im going to run with zero issues for over 70k miles. and hes making about 400 whp. I will have to check the clutch alignment on the splines and see if im happy with it, if not i will buy the thicker flywheel and be done with this B.S.
Click to expand...

does a 12” clutch not work for an LS? That’s what I used, but it’s an old 7.4L. I can make it slip if I really want to.
 
bp71k5 said:
does a 12” clutch not work for an LS? That’s what I used, but it’s an old 7.4L. I can make it slip if I really want to.
Click to expand...

ya i think it should but maybe someone else could chime in for sure. That flywheel I’ve got recommends an 11” clutch so that’s what I went with
 
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