It looks like it has been about a 100 years since I’ve updated anything on the ole Polar Bear Suburban so today is as good as any for an update as there are a few things worthy of posting.
For starters, the ole bear has had a pretty nasty driveline vibration for many years that I whittled at for what seemed like forever. The vibration was a high frequency vibration that pointed to driveline. Back during the Rona lockdown in 2020 I had plenty of time to play with it. After doing a lot of measurements I found the NP241 output shaft had a ton of runout, which made sense as it was wiping the tailshaft bushing and rear seal about every year so ripped it down and did a Slip Yoke Eliminator. The driveline angles had to be adjusted again once the new longer shaft was made as well.
While that made a noticeable change in the vibration it still wasn’t enough to make me happy but life and other projects got in front of it (mainly the K10 breaking in half and needing a major frame job) where I finally got around to getting back on it this summer. Along with a vibration, the bear has had a terrible feeling clutch pedal pretty much since day one when I got it but back then with the TBI 350, the issue was just a flat pressure plate then I replaced that with a used leftover Centerforce from the K10 when I did the NV4500 swap around 2012 using an Advanced Adapters bellhousing. Then in 2015 when the bear got its 8.1 swap I started with fresh hydraulics and a new Centerforce clutch and had the flywheel turned at our local driveline shop. After that swap was complete the bear had a ton of new power but the less than sterling clutch woes continued although they issue felt different.
I dealt with the poor clutch issue for years where it just felt like the release bearing wasn’t pushing the pressure plate far enough. It launched with a lot of chatter and grabbing reverse was near impossible without turning the engine off. Given how inconsistent Advanced Adapters quality is, I suspected the clutch fork pivot ball was in the wrong location, wrong ball or whatever so I decided to pull the AA bell and use a factory GM bell from a 1996+ with internal slave/release bearing, which also required a new clutch and PP. Being on a budget I chose to go with a run of the mill LUK clutch, which worked okay but wasn’t nearly a good performer as the Centerforce. Those changes did make a slight difference but still not enough to make the pedal feel nearly as good as the K10.
Fast forward to this past June, I decided to get a new Centerforce clutch kit for a 1996+ 454 but this time I decided to get a fresh flywheel since that is about the only thing I haven’t changed throughout all of the clutch issues that came to be after the 8.1 swap. As I pulled the old flywheel out and laid it next to the new flywheel it was a complete “AH, HA!” moment when I saw what the driveline shop did 7 years ago. Those clowns completely machined off the lip where the pressure plate rides. The amount of metal they took off was thicker than a quarter and certainly would make a difference in the dept of the release bearing push. The flywheel balancing holes are also on that same outer plane where they wiped those down too!
Long story short, the new flywheel fixed the clutch engagement issue AND the vibration issue that’s been driving me crazy for all these years…….and the Centerforce clutch allows the NV4500 to shift as close to a sports car as one could get. I totally didn't expect this flywheel to fix the vibration as the vibration felt more speed related than RPM related but then again I don't drive these 8.1s at 2500+ RPM at a constant pace in any other gear than 5th. So, for you 8.1L guys with manual transmissions be careful if you ever have your flywheel turned. Probably better off just replacing the flywheel rather than having it turned. Shame on me for not noticing the day I picked up the flywheel from the driveline shop back then.
Good ole Centerforce on left and LUK on right
So, with that success I fell back in love with the ole bear and decided it needed more love so it inherited a hand me down old school Hickey Sidewinder winch that came off my K10 a few years ago, which was a hand me down from my dad's buddy that bought this winch brand new as a dealer installed option on his 1978 K20 way back in the day. It was quite the time consuming blacksmithing project reworking the brackets and skid plate designed for a 73-80 to fit an 81+ with much different frame horns and bumper shapes. Funny, these old winches used tiny 7/16 cable that was only about 2 feet long This time it got treated to 85 ft of 3/8 synthetic rope. I really didn't think a full 100 ft would fit on the spool. I'm still deciding on a hook though......thinking of a Warn Epic Sidewinder, a Factor55 dealeo like the one on the K10 or stay with nothing at all as it is now.
When the Sidewinder was on the K10
I restored an old period correct Warn bumper with a Warn 12k to replace the Sidewinder
Now it lives on the Polar Bear
I made some snazzy bump stops so the plate wouldn’t get pushed into the bumper driving on the highway.
Winch neutral pull rod
100% Jeff Bezos Chinesium winch rope
.....continued
I will share my build list when I get it cleaned up.
