Builds The Clustertruck Rides Again - Refurbishing a 1975 Chevota

[RWBeringer4x4]

Do it right, or do it twice - just very intimidated by the thought of rebuilding one...

Is there any truly "good" way to inspect this bearing? Or would you just replace it based on all of the clutch system evidence to be safe?

Looking at @Vae Victus super-detailed transmission rebuild thread, it looks like he was able to knock the input shaft bearing out from the back.

@Pin_Head - if you happen to see this, I'd love your thoughts on this too...Is it "safe" to replace an input bearing alone, or is this a situation where replacing a single bearing will do more harm than good?

 

[pb4ugo]

My guess to why your pilot bushing is slightly wallowed out, is that your trans input shaft was not properly aligned with the center of the crank. I've run across this b4 in a similar the type of setup like you were running. IIR, you were using a steel scattershield type bellhousing where the 1st installer has to center the trans input shaft with the crank and drill/alter the scattershield for trans alignment. The transmission input shaft alignment to the crank is only as good as the 1st person who installed it. A of friend mine purchased a 40 with the same type of setup. The original installer wasn't even close with his alignment. We didn't have to measure the pilot bushing bore, it was obviously ate up. The clutch disc was in such a bind that you couldn't put in in gear with it running and it would lurch forward if started in 1st gear. Fortunately, I had a cast AA bellhousing that we installed which fixed the problem. I think using the Downey B/housing you purchased will cure this.

I've also run a across throw out bearings that chatter like you describe. I've found that the bearing was in slight contact w/the fingers of then P/P while at rest, eventually the bearing loosens up. The noise goes away when pressure is applied to the pedal. If you look at the old bearing, my bet would be that it spins roughly with no pressure on it, but if you apply a little pressure to the face and spin it, it spins smoothly or smoother. As mentioned b4, this just my guess. Ken

 

[RWBeringer4x4]

My guess to why your pilot bushing is slightly wallowed out, is that your trans input shaft was not properly aligned with the center of the crank. I've run across this b4 in a similar the type of setup like you were running. IIR, you were using a steel scattershield type bellhousing where the 1st installer has to center the trans input shaft with the crank and drill/alter the scattershield for trans alignment. The transmission input shaft alignment to the crank is only as good as the 1st person who installed it. A of friend mine purchased a 40 with the same type of setup. The original installer wasn't even close with his alignment. We didn't have to measure the pilot bushing bore, it was obviously ate up. The clutch disc was in such a bind that you couldn't put in in gear with it running and it would lurch forward if started in 1st gear. Fortunately, I had a cast AA bellhousing that we installed which fixed the problem. I think using the Downey B/housing you purchased will cure this.

I've also run a across throw out bearings that chatter like you describe. I've found that the bearing was in slight contact w/the fingers of then P/P while at rest, eventually the bearing loosens up. The noise goes away when pressure is applied to the pedal. If you look at the old bearing, my bet would be that it spins roughly with no pressure on it, but if you apply a little pressure to the face and spin it, it spins smoothly or smoother. As mentioned b4, this just my guess. Ken

Thanks Ken -

I completely agree with you on the scattershield. This is why I decided to do away with it before I even pulled the engine. Too many unknowns, and there are far better options out there.

As for the pilot bushing - not only is it wallowed out by about a mm, but it was also ground IN even more - this seems to imply that the input shaft was too long for the bellhousing, doesn't it? It appears that it was slowly drilling its way into the bushing, and also wallowing out the inner diameter.

I'm hoping you are right about the throw-out bearing. All signs point to gross maladjustment, and since there was no clutch fork spring it is very feasible to think that the bearing wasn't fully retracting. However, I have to imagine that the input shaft bearing didn't come out of this setup unscathed. Who knows, maybe I'll get lucky. There's really not a ton of play in the input shaft. There's SOME visible lateral play, but my understanding is that this is pretty common.

 

[Pin_Head]

It is possible to replace the input shaft bearing on your H42, but you have probably have to "drop" the cluster gear / counter shaft to remove the input shaft/gear. You might be able to just "walk" the bearing off and back on by putting increasingly large shims under the retainer ring and tapping on the nose of the shaft. It just depends on how tight the bearing is.

How do you know the bearing is bad? They don't tend to fail. It is a ball bearing and it has a lot of wobble in it when the nose of the input shaft is not in the pilot bushing.

 

[RWBeringer4x4]

It is possible to replace the input shaft bearing on your H42, but you have probably have to "drop" the cluster gear / counter shaft to remove the input shaft/gear. You might be able to just "walk" the bearing off and back on by putting increasingly large shims under the retainer ring and tapping on the nose of the shaft. It just depends on how tight the bearing is.

How do you know the bearing is bad? They don't tend to fail. It is a ball bearing and it has a lot of wobble in it when the nose of the input shaft is not in the pilot bushing.

Thanks for chiming in @Pin_Head! The only reason I'm concerned is because of the condition of the pilot bearing, throw-out bearing, and bearing retainer snout on the transmission. All show pretty serious wear consistently with misalignment. I have no real reason to think the input bearing is bad - the transmission ran without significant whining or shifting issues before I pulled it. The only whine I got was in 4th gear, at 50+ MPH under load, it disappeared if you lifted your foot off the gas. This just seemed like standard old transmission gear whine to me...I've got videos of both noises posted somewhere in this thread...

Summary - nothing indicates bearing failure UNLESS the chugging I heard with the clutch in neutral was the input bearing, and not the throw-out bearing. I'd expect bearing failure to be more of a whine (and I'd expect to hear it when the truck was moving) if it was truly the input bearing.

I actually just got off the phone with Georg at Valley Hybrids as well discussing the same thing. His opinion was inspect it as best I can, but probably just run it. Input shaft play and the noises I described didn't seem to indicate anything too sinister with the input bearing.

The only other "tell" was metal powder on the magnetic drain plug - but no big chunks. I'm not sure how much is too much in this case...

 

[Pin_Head]

Unless it was grinding going to 4th, popping out of 4th or noisy in N, it would just run it.

Maybe the clutch fork is putting sideways pressure on the input shaft.

 

[RWBeringer4x4]

Nope, no grinding beyond occasionally going into reverse. No popping out of gear. No issues shifting up whatsoever.

The only possible issues were: It WAS noise in neutral (chugging noise, no whining) and a little slow to syncronize on a downshift (whining and hesitation downshifting, but no grinding). That and the whine at 50+ mph with my foot on the gas. If I let of the gas, the whining stops.

 

[RWBeringer4x4]

@pinhead - here are the videos:

Whining in 4th with my foot on the gas (starts at about 28 seconds):


Here's the downshifting noise:

 

[RWBeringer4x4]

chugging in neutral:

 

[Pin_Head]

I'm not liking the noise in N. I would take the bearing retainer off and inspect the bearing races.
It could also be the needle bearings that pilot the main shaft nose in the rear of the input gear shaft.
H42s are cheap enough that I would get another one before I spent the time rebuilding one.

 

[RWBeringer4x4]

I'm not liking the noise in N. I would take the bearing retainer off and inspect the bearing races.
It could also be the needle bearings that pilot the main shaft nose in the rear of the input gear shaft.
H42s are cheap enough that I would get another one before I spent the time rebuilding one.

I'm planning to pull the retainer and take a look, for sure. Wouldn't I need to remove the bearing entirely to inspect the races, or am I just looking between the "balls"? Is there any way to inspect the needle bearings for damage or play?

I'm hoping that the "chugging" noise was the T/O bearing riding the pressure plate fingers. That seemed to be the going consensus previously but I could never get a good enough look to confirm...

I have no interest in rebuilding the transmission, I've seen used ones available for cheaper than a rebuild kit - If this transmission was toast, I'd be looking to replace it. I know it isn't a truly good test, but everything seems to move smoothly when spun by hand (no grindnig/grittiness).

 

[Pin_Head]

Yes, you just have to peek between the little balls

The needle bearings tend to wear by spalling and leave little flakes of metal on the magnet.

 

[RWBeringer4x4]

Yes, you just have to peek between the little ballsView attachment 1417772

The needle bearings tend to wear by spalling and leave little flakes of metal on the magnet.

@Pin_Head - Let me refer you to post #910, on page 46. Something like that? Not sure what "normal" metal on the magnet is vs. excessive.

 

[RWBeringer4x4]

Bit the bullet and dug 7 bolts deeper. I honestly can't see anything wrong with the input bearing.

I have marginal lateral play, and just a TOUCH of in/out play (fractions of a mm)

The races don't look particularly chewed up. Definitely not something I can easily get a picture of:

 

[RWBeringer4x4]

I think I'm going to risk running the transmission with the new clutch/bellhousing setup, as much as I may regret it when everything is back together, I can't find anything that screams "damaged input bearing" beyond the noise the truck was making - time will tell if this was a throw-out bearing, the clutch clearancing it's springs on something, or the input bearing. I'll change one variable (the clutch) and see where that gets me.

I got the driveline back together for test fitting tonight. Getting the engine and trans aligned solo was quite a challenge, even with no pilot bearing to contend with...a little taste of the future...

Looking at where the new Downey bellhousing places the input shaft, it doesn't appear that I'll have further issues with the shaft trying to drill through the pilot bearing, it seems to align nicely:

Meanwhile, radiator number 2 showed up. After an online Toyota parts house delivered a damaged radiator, then took it back, and refused to ship me a second one, I decided to take a chance on an open box CSF 4-core aftermarket radiator. It was $100+ cheaper. Showed up with only a couple of bent fins - easy enough to fix...

Made in Indonesia, so you know it's good


The only thing I don't love about this one so far is the crappy plastic thumb-screw petcock. I may have to devise something sturdier there.

I also got word that the Walker 2" Y-pipe is finally back in stock - so another piece to the puzzle should be on its way!

Lastly, my friend dropped this off at the house over the weekend:

If it performs well setting up the engine mounts, I will likely buy it off him when we are done. He's moving and doesn't feel like taking it with him.

is getting pretty tired of half a truck sitting in her front hallway (out of garage space) - so hopefully my welder friend can get here soon, and get this show on the road!

 

[thebigredrocker]

I get that sound also on my 76 w/sbc. I always push in my clutch during startup. When my engine is cold and I let off the clutch in Nuetral to warm up, I not only notice that sound, I get a drop idle rpm's. Do you notice a drop in idle when cold? I figured I just need to adjust my slave. I'll be curious what you do to eliminate that sound. To me the sound is similar to tank tracks or a diesel caterpiller. I've been meaning to ask @Downey what his thoughts are.

 

[RWBeringer4x4]

I get that sound also on my 76 w/sbc. I always push in my clutch during startup. When my engine is cold and I let off the clutch in Nuetral to warm up, I not only notice that sound, I get a drop idle rpm's. Do you notice a drop in idle when cold? I figured I just need to adjust my slave. I'll be curious what you do to eliminate that sound. To me the sound is similar to tank tracks or a diesel caterpiller. I've been meaning to ask @Downey what his thoughts are.

I never noticed a significant drop in idle RPM's from letting the clutch out - but that certainly implies that you have something creating added resistance in the driveline with the engine in neutral. Perhaps the clutch isn't entirely disengaged in neutral? If the clutch is not adjusted properly, the throw-out bearing may not completely disengage from the pressure plate fingers. Depending on how bad it is, this can lead to the throw-out bearing spinning constantly while riding the fingers (that's what I'm HOPING that sound was). OR, if it's REALLY out of adjustment, it will do that, plus keep the pressure plate partially engaged, which could be adding some resistance to the driveline and causing your idle to drop. Just a theory. Maybe take a look through the clutch fork hole in the bellhousing while the engine is running and see if you can see your throw-out bearing spinning. This is what I SHOULD have done before I tore the whole thing down.

Another thing I noticed was that the sound was much louder/more pronounced if I let the clutch out quickly, vs. slowly and gently letting off. Then it would become more of a consistent "whir" rather than a "chug." No clue! it's going to be a while before this is all hooked up and back together but I'll certainly keep you posted.

 

[SuperBuickGuy]

get the radiator pressure-tested (or do it yourself) to be sure that one tube doesn't need a touch of solder to make it whole.

 

[RWBeringer4x4]

Baby steps - just plugging away at small stuff until my welder gets some free time...

Got the scab plates to the old transfercase mounts cut out. For as horrible as the front motor mount welds were, these ones were pretty sturdy...I got a little overzealous with the grinder...I don't think I've compromised the frame's integrity but I'll probably backfill with weld anyway for aesthetics.

My walker Y-pipe (p/n 42087) arrived after several months on back-order. Since I am keeping the exhaust-mounted alternator for the time being, I'll need to source a heat-riser delete spacer to have it clear the oil pan. I test fit it anyway.

I'm going to need to get a little creative to have space to get to the oil filter, but since this is a Chevy "OEM" replacement I imaging it won't be too challenging...

Sure beats the previous setup, where the exhaust crossed over directly under the transmission oil drain....

 

[71FJnick]

The y-pipe looks nice, should make for clean exhaust routing.