I don't believe the lip would come loose. Can't see a reason for it to do so, but I guess there's always a chance. Please look at the attached image. The yellow pointer shows where the lip would be located after the sleeve is driven on...it could ride anywhere in this machined "U" channel...front, middle or rear. The light blue pointer is where the overhang of the Speedi-Sleeve would have to be trimmed (flush with the crank). As I recall this U channel is about 3/8" deep and the lip of the Speedi-Sleeve is around 1/4" tall.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
Believe my crank is smooth enough for rope to do as good a job as a rope seal can do. But with all this slinger talk...went ahead and ordered speedi sleeves (for both ends of the crank) for about $50. After that's done, will probably use neoprene, we'll see. Thanks all for the part numbers and info, as boring as that is.
Matthew 6:33
1952 Chevy 1/2-ton 3100 Late '55 235/SM420/torque tube 3.55 Dalton Highway survivor (using original 216) www.truckwithaheart.com
Just to confirm- if you are attempting to replace a neoprene seal by removing the pan only, you are not likely to be met with success, so rope seal only in that case?
Last edited by Norcal Dave; 05/20/20237:03 PM.
~ Dave 1950 Chevrolet 3600 3/4-ton with 261 engine & T5 Transmission
The safest, most accurate way to trim the sleeve would be with the crankshaft in a lathe, which is how I'd do it. Otherwise, try using a small angler grinder and a very light touch to nibble the excess length away, followed by a final touch-up with a file. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Just to confirm- if you are attempting to replace a neoprene seal by removing the pan only, you are not likely to be met with success, so rope seal only in that case?
No, I wouldn't say that, Dave. It seems there's been a misunderstanding about this seal so let me try again to do a better job. Please look at the image below. The green arrow points to the trapezoid-shaped channel where either seal (rope or neoprene) will go. The neoprene seal has been designed to fit neatly in that channel and push against the crank with a wiping lip...the tip of which faces inward toward the oil pan. The rope seal must be forced into the channel and then pushed down (preferably with a tool...could be an improvised tool) to get as much of that rope seal in the slot and get it flattened and as evenly distributed as possible. The red arrow points to the small amount of space between the crank sealing area and the engine block. Your rope seal is currently in that channel and when it was installed it was squashed down (hopefully) so that a bit of that rope seal will be pushed over into that bit of space also. The nature of the installation of this seal, the tight space in which to work and the inability to install it as GM instructed with the crankshaft in the vehicle make installing the rope seal with the engine in the vehicle very challenging. And these challenges are what make failure of that seal (when installed with the engine in the vehicle) so common. Back when this seal was made with asbestos there were some mechanics who could replace them and have them work correctly...but those were not "dime a dozen" guys. They were rare and that rope seal was entirely differently made. Now, let me make the rope seal picture a little more bleak...today's rope seals are some sort of blended rope (cotton/poly maybe or possibly a nylon/poly rope) impregnated heavily with graphite. I'm not certain there is a knife nor razor blade on the face of this troubled planet of ours that can cut that rope without leaving frayed threads. I've tried many times and the moment that rope is cut the threads start to come apart. No matter how carefully and correctly the "new" rope seal is installed I think the loose threads are where the problem will begin. In contrast to the neoprene seal, the rope seal is designed to fit as firmly as possible against the surface of the crank. So it naturally wants to turn when the crank rotates...and it will almost invariably do that. And to hark back to replacing the rope seal, it is important to understand lowering the crank a bit is mandatory. You might be able to remove the old seal. There are tools made which look like stiff pieces of wire wound into a screw on the end...the idea being you could screw the thing into the old seal and pull it out while rotating the crank in the direction you're pulling. I should tell you I have made that little procedure work all of one time in almost 60 years of fiddling with these. If you drop the crank a bit, you will remove the pressure on that seal and you'll make it much easier to remove. Most commonly a "Sneaky Pete" tool is used to grab the end of the rope seal you're able to dislodge and help pull it out...this tool works like a Chinese finger trap. Bottom line is even if you're patient and lucky enough to remove the old seal without lowering the crank a bit you won't be able to install a new one correctly without lowering it. If you want to grade my paper on that, please ask Jerry, Evan, Panic...any of those guys.
Okay, on to the neoprene seal. Depending on how yours was installed, you might be able to push it out using the small end of a chopstick to get it started without lowering the crank, but it will be mandatory to turn the crank in the direction you're removing it. Here's why...when that seal was installed, there should have been a thin layer of non-hardening gasket sealer applied to the part which will fit into the channel...both to keep oil from seeping around it and to keep it from wanting to rotate with the crank. And that seal can not be straightened out as it is removed. In the center of it is a half-circle shaped piece of hard spring steel. If you have dropped the crank a bit you can free this type of seal and rotate it out. Installing a new one is going to go much better if you lower the crank...because you will need that thin layer of gasket sealer on it and installing without lowering the crank will wipe that off. If you decide to lower the crank a bit, here is how I do that: remove your transmission or slide it back enough to release the input shaft from the pilot bushing, remove the oil pan and harmonic balancer (important because you need some room there for the front end to drop also and you don't want to wreck that seal nor distort the timing gear cover. Then remove the rear main bearing cap and loosen all other main bearing bolts. Some will remove all the rod nuts, remove piston rod caps, place rubber hose on each rod bolt and push the pistons up and out of the way. But you can lower the crank without doing this...it just makes it easier to move the crankshaft.
And another word about the crank sealing surface. The old rope seal was known to harbor oil, moisture, acids, all sorts of stuff and consequently over time the surface of your crank might become pitted. In some cases pitted badly. For either of these seals to work at their best the surface of the crank must be as smooth as possible. Even for the one-piece seal to work well and be long-lasting this must be the case.
I hope this is helpful. If you have any questions at all, please mention them.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
The safest, most accurate way to trim the sleeve would be with the crankshaft in a lathe, which is how I'd do it. Otherwise, try using a small angler grinder and a very light touch to nibble the excess length away, followed by a final touch-up with a file. Jerry
X2 on what Jerry said. You can also use a Dremel tool with the cut-off attachment they make to trim it off and then touch up with a file at an angle. If you use the Dremel tool, you can measure the part you need to cut off and then carefully put a piece of masking tape around as a marker. Then cut using the masking tape as your guide line and finish with a file.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
Ditto to all of the above- - - -although my success rate has been just a bit better than Jon's. Over the past 60-something years, I've changed maybe half a dozen rope seals "in the vehicle" without creating a worse leak. Usually, I cheat- - - -lower the crankshaft a little, drive a thin stainless steel shim between the upper seal rope and the block, and install a new rope on the bottom. The stainless steel strip that retains the rubber on a windshield wiper blade works pretty well to tighten up the top rope.
Back when labor time was figured at about $15.00 an hour, it was possible to break even, if not actually make a profit on that kind of work. Those days are as long gone as getting change from a dollar for a lunch of a hamburger, fries, and a Coke! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
I'm in the process of installing a piece of barn door track over my lathe. I'll use it with a double sheave block and tackle and some nylon rope to manhandle heavy stuff on and off the lathe without having to bust a gut in the process. Those skate wheel type rollers in the square channel will make handling something like a stovebolt crankshaft a lot simpler. I'll probably do the same thing over my crankshaft grinder eventually. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
You know, Jerry I have spent a lot of time thinking about any possible way to improve that rear main seal without machining the block (since that's outside the reach of most people), but so far I just haven't been able. Of the possibilities I've considered: specialty o-rings (but the makers of those tell me that while they do make them for rotating shaft seals the rpm and temperature work against this application---one fellow thought you'd be replacing the seal every 1,000 miles or so), lip seals which mimicked the neoprene-type seal but which incorporated a bona fide spring piece that would push against a thin viton lip (one engineer at Fel-Pro told me this would be possible but it might become a charity event as the cost of development and the cost of production would make reaching a break-even point very doubtful, adding a slinger to slow and redirect oil flow (which as I've said seems natural with the Speedi-Sleeve lip)...all sorts of things. I'm open to any sort of suggestion from anybody. I've even considered machining a groove in the lower bearing so as to force the majority of oil to exit at the bottom, but some folks have told me there would be challenges there.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
True. Length and looks don't matter much. Just to illustrate there's a quality difference and you begin to understand why one costs ten times more than the other.
Matthew 6:33
1952 Chevy 1/2-ton 3100 Late '55 235/SM420/torque tube 3.55 Dalton Highway survivor (using original 216) www.truckwithaheart.com
Of the possibilities I've considered: specialty o-rings (but the makers of those tell me that while they do make them for rotating shaft seals the rpm and temperature work against this application---one fellow thought you'd be replacing the seal every 1,000 miles or so),
The only concern I have with the speedi sleeve is whether the slinger lip can deprive seal of whatever amount of oil is needed to keep it cool. Hopefully it's unfounded.
Matthew 6:33
1952 Chevy 1/2-ton 3100 Late '55 235/SM420/torque tube 3.55 Dalton Highway survivor (using original 216) www.truckwithaheart.com
I think the concern of starving the seal will take care of itself. Let's think about the U channel. If you study the crankshaft, you'll see it bevels where it meets the part which is the crank sealing surface. In fact, blow up the image I attached to my post and you'll see it clearly. That means any oil that runs out of the rear main will run along the shaft to that upward facing bevel and be slung straight out radially. That bevel will actually streamline the radial slinging because it minimizes the amount of direction-changing the oil must do. So all the oil runs to the rear side of the U channel and bathes the sealing area. Even with a .001" bearing clearance that will not be a small amount of oil although if the bearing clearance is .003" or so, the amount will become notably more. At .005" or more we're talking an abundance of oil.
The oil present on the sealing area is enhanced by the natural slope of any of these engines when in the vehicle. In fact, due to the design and orientation of the U, oil that lingers in the U will be continually present on the sealing area.
The Speedi-Sleeve orientation is the opposite. The bevel will be on the inside (facing the rear main bearing) and that will slow the oil down a wee bit as it changes direction. Then it or any slinger with a straight vertical edge will sling oil radially, but this time if the slinger was set so it was as close to the rear edge of the U as possible without risking interference then as the oil was slung up into the U channel oil present on the sealing area could be reduced as long as the U wasn't filling up with oil all the time. And conversely I think if the slinger was set as close to the front side of the U channel as possible it would limit the amount of oil that could pass by the slinger on to the back side of that channel. But given the slope of the installed engine, I can't imagine that a slinger would eliminate oil present around the sealing area...minimize it, yes that is the hope here.
But here's where Jerry and his knowledge of things like this will be necessary, so hopefully he'll add an opinion.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
Jon, I'm working on designing a machining fixture that can be used in a low speed drill press tall enough to stand the block up under the power head to cut the counterbore for the full circle lip seal. It will be a high speed steel shell end mill 4 3/4" in diameter, with a ball bearing support that centers in the main bearing bores. The cutter will have about 20 cutting edges, so it should cut an accurate counterbore with one pass. Then all the machinist would need to do is make the cut in the block and the main cap the correct depth. The cutter would be a bit e$$$pensive, but it would pay for itself in 4 or 5 jobs, and it can be resharpened without changing the OD of the cut.
Here's the seal, one of several with the correct dimensions that are available.
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Jerry that's very encouraging. Is that shell end cutter something that would have to be made or are they stocked in that size? Is it a one piece cutting head?
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Found another one, to rough out the cut a little undersize- - - - - -Now, if I can just find a radial drill press to buy for a bargain price- - - - -LOL!
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Interesting. Did you get the first one on a best offer basis? How sincere does the drill press need to be, Jerry? As I'm sure you know there's a wide range of those out there. I have one that was given to me several years ago. Not terrible but early Chinese.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
Does the Chevy crank have a slinger built in? This is a picture of the rear journal & main of my GMC 302 showing its slinger.
Do I need to remove the crank to clean up the surface where the rope seal has left deposits or can I just rotate the crank cleaning a small portion at a time? I have another early (no zip code on the package, so probably earlier than 1963) rope seal still in the original GM packaging.
Last edited by Bill Hanlon; 05/21/20236:07 PM. Reason: forgot picture
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
I'm sure others will chime in, Bill. I've seen some GMC inline sixes with slingers like that. If I remember correctly the 228 I had was the same as the image you've posted, however it was almost 50 years ago. Chevy 216, 235 and 261 didn't have any slingers...but it has been my belief for a long time slingers would have helped with the leaking problem. The GMC (as you can see) is different in that the sealing surface is lower (where the crank is a smaller diameter) and the Chevy seals up on the flange edge...the flange connecting to the flywheel, that is. If it was me I'd clean that area as well as I could before replacing the rope seal...you'll remove the crank to replace that seal anyhow, yes? I have some rope seals I saved since I was in high school...early to mid 60s.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
Bill, if you don't mind could you post an image of the rear main cap from your 302? I see where the slinger was positioned about .015~.020" from the rear edge of the oil slot there and I've been personally wondering where the best place to locate one on the 235 would be. I'm curious to see how GMC provided for oil exiting that channel.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
Jon: I'll start a new thread instead of corrupting this one.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
Jon, I've got an old Delta-Rockwell drill press that I've modified with a second motor and a bunch of pulleys to have 24 speeds available, but it's a little too light duty to do the block boring I'm thinking about. I'm shopping for something like a Powermatic floor model, or maybe something similar, with a geared power head instead of a belt drive. They show up on Ebay pretty often at fairly reasonable prices. I believe the spindle speed would need to get down around 100 RPM or slower for that big cutter to work properly. The milling fixture I'm designing will have a universal joint in the drive system, so a perfect alignment under the spindle probably won't be necessary. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
