SM420 Clutch/Flywheel Probs - Pirate4x4.Com : 4x4 and Off-Road Forum

1943gpw · 09-30-2006, 07:27 PM

Is it normal for there to be some pre-load on the clutch diaphram from the throwout bearing? When I bolted up my SM420 to a 225 V6 (adapter bellhousing) the clutch springs have some pressure against it from the throwout bearing. There is no slack allowing the throwout to slide some.
What are your thoughts?

CJ3A Willys · 09-30-2006, 10:31 PM

Sounds like your using the wrong thro-out bering. There is a short and tall verssion. Also the contact side of the bering could be either rounded or flat, so be sure to get style that matches your pressure plate. I use Application 65 thru 73 el camino w/M22 muncie 1 1/8" input shaft. Its the short flat front verssion. If you need the rounded front verssion. They came in early 60's 1/2 tons. (I think). Go to your local NAPA and ask for thier best old-school chevy guru. They should be able to hook you up. Good luck.

1943gpw · 10-01-2006, 06:41 AM

Thanks for the help. I'll try that.

CJ5inFourWheelDrive · 10-01-2006, 06:06 PM

Just went out to the garage and snapped a pic for ya: The throughout bearing on the left is NAPA part number N1488 for a 60's truck with an SM420. The bearing on the right is the newer model that will also work and is NAPA part number N3068-SA this one has a plastic case so I'll probably end up running the earlier model. I got the part numbers from either searching on here or from Novak or Advanced Adapters as I have both conversions but will be running the Advanced Adapters setup. The fork in the middle is a SM420 fork as I remembered you had asked about the horse shoe clip. If need be you can see what the clip looks like both installed and out of the fork. Good luck and keep us updated with pics, hope this helps man.

1943gpw · 10-01-2006, 08:56 PM

Thanks for the help. This takes alot of the frustration out of dealing with the avg parts counter dope who want's to know what make and model!!

09-30-2006, 07:27 PM	#1 (permalink)
1943gpw Registered User Join Date: Dec 2005 Member # 64341 Posts: 13	SM420 Clutch/Flywheel Probs Is it normal for there to be some pre-load on the clutch diaphram from the throwout bearing? When I bolted up my SM420 to a 225 V6 (adapter bellhousing) the clutch springs have some pressure against it from the throwout bearing. There is no slack allowing the throwout to slide some. What are your thoughts?

09-30-2006, 10:31 PM	#2 (permalink)
CJ3A Willys Registered User Join Date: Aug 2006 Member # 78398 Location: Las Vegas, NV Posts: 34	Short through-out bering Sounds like your using the wrong thro-out bering. There is a short and tall verssion. Also the contact side of the bering could be either rounded or flat, so be sure to get style that matches your pressure plate. I use Application 65 thru 73 el camino w/M22 muncie 1 1/8" input shaft. Its the short flat front verssion. If you need the rounded front verssion. They came in early 60's 1/2 tons. (I think). Go to your local NAPA and ask for thier best old-school chevy guru. They should be able to hook you up. Good luck.

10-01-2006, 06:06 PM	#4 (permalink)
CJ5inFourWheelDrive Registered User Join Date: May 2003 Member # 19668 Location: Central, PA Posts: 906	Just went out to the garage and snapped a pic for ya: The throughout bearing on the left is NAPA part number N1488 for a 60's truck with an SM420. The bearing on the right is the newer model that will also work and is NAPA part number N3068-SA this one has a plastic case so I'll probably end up running the earlier model. I got the part numbers from either searching on here or from Novak or Advanced Adapters as I have both conversions but will be running the Advanced Adapters setup. The fork in the middle is a SM420 fork as I remembered you had asked about the horse shoe clip. If need be you can see what the clip looks like both installed and out of the fork. Good luck and keep us updated with pics, hope this helps man. Attached Images __________________ (1975 Jeep CJ-5) Being built: 2x4 A-500C frame, C&C 14 bolt w/discs & Detroit, D44 mini-spool, Flat Tops, Mad Mac Double Arms, 4.56's, SM420, D300, AA & Novak adapters, SOA on 2in. BDS YJ springs with a reversal, extended wb; 6in. front, 3in. rear, TJ flairs, hummer rims, hydroboost w/68' Vette M/C…

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10-01-2006, 06:41 AM	#3 (permalink)
1943gpw Registered User Join Date: Dec 2005 Member # 64341 Posts: 13	Thanks for the help. I'll try that.

10-01-2006, 08:56 PM	#5 (permalink)
1943gpw Registered User Join Date: Dec 2005 Member # 64341 Posts: 13	Thanks for the help. This takes alot of the frustration out of dealing with the avg parts counter dope who want's to know what make and model!!