The Stovebolt Site Forums The Shop Area Engine Shop Clutch/ Rear Main/ Bottom End

I've got a situation with some parallels to another active thread but figure it's worthy of a stand-alone post rather than mucking up the other. It's a case of needing to reign in the snowball effect but not be silly and short-sighted, either.

A clutch replacement is in my relatively near future. I've been putting it off because 1) Enjoy driving the truck, and 2) Unlikely to be a "fun" job. For context, this is a late 235 in a 1951 truck, with an SM420 behind it. The engine runs really strong, but the low idle oil pressure and low/medium level of blow-by...suggest it's not pristine internally.

Clutch job makes me think "might as well" freshen up the rear main. Having the pan dropped makes me think "might as well" inspect/replace rod and main bearings. The rear main doesn't seem to be "actively" leaking, but it looks like it may have just "scabbed over" from a leak some decades ago before it was parked by the PO circa 1980.

Here's my multi-pronged dilemma: I don't have a great way for the truck to be torn down in a non-drivable state for more than just a few days...let's say a week for discussion purposes. The shed where it's parked has no electricity and a gravel floor. I'd greatly prefer to do the work in the driveway, closer to my tools, and power, and much easier to use jacks and stands, etc. To get this job done swiftly and not linger on forever, I'd need to have all the parts sourced ahead of time. If I were to replace bearings, I wouldn't even know which size is needed until the pan is off.

Here are a couple ways I could slice this:

1) Forget the bearings. Oil pressure is around 12-15 at hot idle, immediately pegs the gauge at any RPM above idle. Surely some excess clearance in the bottom end but probably has some life left. Do my homework to get the right clutch parts and a replacement rear main seal (should be lip seal - 1962 model engine).


2) Buy an oil pan gasket. Pull the pan to inspect (maybe even plastigauge?) the crank and bearings. Button back up with the pan gasket affixed to either the pan or the block, but not both. Drive it back out to the shed. Get the right clutch parts ordered, get the right bearings ordered, and the rear main. Do all the work in one shot when all the parts are in hand.

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Weighing all the factors....I'm leaning to option 1, but open to some feedback and suggestions. Perhaps there's another alternative I haven't considered.

For what it's worth, there's a 3rd path I could take which would mean FULLY embracing the snowball effect:
Install the T5 that's been patiently waiting in the wings for a few years. That option has it's own subset of mini-snowball effects. It would need, at minimum, an input shaft swap. But then should I go ahead and rebuild it pre-emptively?

You could do the "shim the top seal" trick by tapping a piece of stainless steel scavenged from a used windshield wiper into the groove above the seal, and replace the bottom rope seal in the bearing cap. It sounds like you still have enough oil pressure not to have to replace any bearings.
Jerry

Does that work on a neoprene seal? This one should be that type.

Nope- - - -rope seal only. You can swap an upper rubber seal by just loosening all the other main bearing cap bolts a couple of turns and letting the crank drop down a little. The rubber seal engines will also have the upper main bearing shells that can be rolled in and out with a cotter pin in the crankshaft oil passages.
Jerry

To get the right clutch parts , I would remove the old first and match up.
but thats just me.

I'm with Jerry on the ws wiper stainless steel piece and the condition of the bearings, but I have been surprised so I'll add something about that in a minute. I've seen that ws wiper trick done since I was in high school and it usually does help. Measure the length on the bottom cap, cut the stainless piece to fit, bevel one end and slightly radius the edges (forming the top side) and tap it in slowly. If you drop the pan and find you have a rope seal and are tempted to swap to a rubber/neoprene/viton blend rear main seal, please make sure you rotate your crankshaft 360 degrees while wiping & inspecting the surface very well. Any roughness, pitting, etc will chew the rubber seal up pronto. If you see any pitting, etc and want to change things, my suggestion would be to buy the new rubber seal and the proper Speedi-Sleeve for the rear of the crank. Drop the crank, install the sleeve using some red loctite and let that be your nice new surface.

If you check the bearing tolerances with Plasti-Gage (which isn't perfect but is reasonably accurate) and you get an unwanted surprise...say for example something like .006" or .007" (which I don't expect but is possible)...you do have the option of using some .0025" or .003" shim stock material and very carefully (using 220 or 240 grit wet/dry paper on a piece of glass) remove just a wee bit from the ends of each bearing half...and please let me repeat: just a wee bit because .0025" is just a hair more than half the thickness of a piece of common copy paper. As long as you remember you have to shim both upper & lower by the same amount (1/2 of the total...in my example .005"/2=.0025" to get you back to a really nice .001" clearance or .006"/2=.003"). The last time I did this I cleaned each bearing half really well and set each upright on the piece of glass and measured before/after at the apex of the curve and stopped when I could see I had sanded off the amount I was shimming by. It didn't take long, either. You can find stainless steel shim stock on Amazon in thicknesses as small as .0007". That way you won't have to do new bearings at this point in time. There is a shim material made thicker in the center and thinner on each end but that's different. It was designed to be used if you were only going to shim one bearing half (the idea being if you had a tolerance of .007" the shim at the center would be .007" thick and on each side would be .0035" thick so it would balance out...sort of. If you're shimming both, you want it equal all the way around. Good luck.

Jon, you brought up another issue I meant to ask about. I can’t find a part # listed for a rear crank repair sleeve. Anyone have one? Or perhaps the dimensions so I could look up the proper sleeve?

The seal surface on a 216 crank is 3.875" OD x .645" thick. Those dimensions should get you the right speedi-sleeve PN by checking HERE. I believe this one would work.
I think you'll be a little shocked at the cost of one that size, but I may be wrong. I went with machining the block for a full circle lip seal instead.

I think the Speedi-Sleeve part number is 99387. eBay is often a place to find them for less $$.

Am I right in thinking you’d have to remove the crank to install a rear sleeve? Or could you drop it just enough to get it on?

There won't be enough room to drive a speedy sleeve on unless the crank is all the way out of the engine. It's a good idea, though, if you do it during a full rebuild. BTW, that full circle lip seal will stretch enough to use it with a speedy sleeve. (.015")
Jerry

All of these motors mark their territory in some fashion. It’s just the nature of the beast. This is why when a lot of us were growing up, there was a wide dark black stripe down the middle of every concrete road.

So if your motor is running, not really leaking from the rear main, why not just leave it undisturbed? Do the clutch, pressure plate, throw out bearing and pilot bearing and keep driving it for the time being.

On the parts issue, because it’s a 62, there are three possibilities, 11, 10 and 9.5. So you really do have to take it apart to see what you have. If you have an 11 inch clutch, that might be hard to find rebuilt or new locally. A good resource for the right parts is HR Clutch in Bensalem pa.

http://hrclutch.com/

Pull the tranny, remove the parts, remove the flywheel, Resurface the flywheel, install the new parts.

Sometimes easy is good.

I more or less agree, Mike. Just need to look closer at the active/past state of that area. Don’t want to oil-soak a brand new clutch if the “scab” breaks loose.

Your comment about some mid rpm blow by makes me think you might be ready for a ring job. Re the clutch: I bought my stock replacement 66 11” clutch kit from AutoZone. Works great behind the 454 so far & was very affordable. It came in overnight.

Removed the clutch cover tonight* and had a look-see. Although it’s far from dry under there, I’m not convinced much/any of the grossness is from the rear main. The engine side of the flywheel is dry and clean. The pressure plate is amazingly dry and clean. I will attach some pics but they are pretty lousy.

I’m not an expert on rear main leaks. Open to some feedback.

* Clutch cover turned into its own minor fiasco. Need some guidance on that once I’m calm enough to tell the tale.

I am in the middle of a Transmission swap on "Thor", 1958 4400 / 235. It was definitely in need of a rear main seal. If your Oil Pressure is as you say 12-15 at idle, that's great.

If your Bellhousing doesn't look like this on the inside, and is relatively clean, then I agree with Dragsix. Replace the clutch and just drive it.

BTW: My clutch turned out to be an 11 inch.