308 rear main seal

Chris Smith

Anyone know if a neoprene type rear main seal is avaliable to replace the rope seal on a 54 308 ?

[Deleted User]

Criss - Dale Cooper advertises them in the WTN. (513) 821 6200. Norm

duncan

use a seal from a 318 cu. inch Dodge v8 fits like a glove. duncal

onerare39

Hudson308 wrote:

Chris Smith wrote:

Anyone know if a neoprene type rear main seal is avaliable to replace the rope seal on a 54 308 ?

I think I read here that Dale Cooper has some now... maybe someone else can confirm that.

Oops... missed it by.... THAT MUCH! :P

I can confirm that... I just received one from him last month.

John

duncan

I am sorry I should have said use a neoprene rear main seal from a 318 Dodge v8 engine.Fits like a glove duncan

[Deleted User]

Ditto on Dale's seals I got some from him as well and they are perfect fit you do not have to trim anything.

Kdancy

Duncan,
What years 318?

russmaas

Basically Dale trims these down as do we. When you buy over the counter , just cut the ears off and trim with a bench grinder and make sure it sits about 1/16th above the cap and block.

Ol racer

FYI
Ive installed a few Mopar 318 neopreme rear seals now by trimming the tabs slightly then put a dab of the more expensive Permatex Black RTV in each corners with no problem.

RL Chilton

Surely so, Ken.  Especially if yo don't have to do any grinding, which can give you a variable height difference. 

Ol racer

FYI

Be sure to research the later model crank Diameter... For some reason I recall something mentioned on the old Forum about using newer 318 seal, but I could be wrong...

Also, somewhere I read of rotating Neoprene Deal slightly so not have gap in the corners

(Maybe I shouldnt read so much)

Glowplug

The crank on a 318 is several .000 under sized from a big block crank.

Frankvintagefullflowcom

The early (Fel-Pro P91055-1 winged) and the late (FP P95482-2) versions are dimensionally identical, however, the late "wingless" one has a double lip seal to provide a dust seal on the outboard side. I think it's important to note that the ends of either version aren't cut square on both ends. In both cases, the right hand end of the upper half and the left hand end of the lower are formed with an upward angle at the lip(s), presumably to assure sealing at the interface.

As pointed out by someone, I like to stagger the ends so that they don't align with the parting line of cap and block. It eliminates the possibility of pinching material at that point.  It looks like the Hudson seal groove is correct for the Chrysler seal but I don't have a Chrysler on hand to check it. There's a little extra room in terms of thickness but I'm sure it's not an issue.

F 

f

Frankvintagefullflowcom

I'll need to chase down a Chrysler block and crank for a better comparison. I'm curious about the diameter of the Chrysler seal journal. With the seal halves laying on the bench, the later (brown) version looks to be splayed out somewhat as compared to the other, making it loose on the crank. It would be squeezed inward upon installation, taking up that apparent difference. Seal journal dia. is the key piece of the puzzle. I see ~2.640" for the Hudson.......just don't know the Chry. dim.

I don't think we can settle for the accuracy of a "ground-down" version. I've heard that many have successfully used it but repeatability of a hand modified part (assuming that it is) is questionable. Too important to leave to chance.

F

Frankvintagefullflowcom

After some investigation, I realize that the Chrysler seal does need some modification to fit the Hudson block/main-cap groove. It will protrude about a sixteenth on one end if flush on the other. So.... the groove diameter must be larger on the Chrysler block/cap.

So.....I stand corrected, in that each "half" needs to have the straight end trimmed to fit, leaving the angled end to provide some "crush" at the lip. Since the Chrysler seal journal dia. is 2.645" and I measure 2.640" on a very "experienced" Hudson crank (virtually identical), it's reasonable to assume that the difference is in the depth of the groove, that is, the Chrysler groove diameter is greater, leaving the ends protruding above flush on the smaller dia. Hudson groove.  Anybody follow that?            Hello?           Hello?            Is anyone out there? Testing....testing. (thump, thump thump) Is this mic on?

F

Frankvintagefullflowcom

Just to finally beat this to death, I have found that the installed ID of both seals is the same. The 40245 was made to replace the original woven "rope" packing in a slightly larger groove. The 40181 was made for a groove diameter that was smaller in the late 318s.

(I believe Ken reversed those numbers in the previous post)

Bottom line.......The Brown 40181 won't work because the larger groove won't squeeze the OD down enough to properly contact the crank seal journal in the Hudson.

Quote from the Fel-Pro tech guy:

"In regards to the differences in RMB seals, the BS 40245 for the early applications is taking the place of rope seals so the seal needs to be a bit larger due to a larger groove space. Later applications came with a rubber lip seal from the factory so the groove is slightly smaller. The journal size of the crankshafts did not change through the years."

 F

Ol racer

F.Y.I.
Regarding  Mopar 318 rear main seals, I have them in several motors without any drip, however, the latest one I installed really leaked. Apparently  either the Main groove is slightly larger not allowing the Seal to compress to Hudson's 2.500 Journal, or the Seal is slightly off. Going forward, I will use the BEST Brand Seal, either Neopreme or Rope.

Ol racer

Tip on Installing a Rope Rear Seal 'In Chassis'..My Hudson seal drip was annoying so figured simply roll in a Neoprene Seal, however, afterward dripped worse. Like I mentioned above, crank seal journal may have minute scratches, or the cap groove is slightly larger.
After researching learned a Rope Seal is far more 'forgiving' however modern Rope Seals in gasket sets (except Best Seals) are made from inferior material & unreliable, thanks to E.P.A. Reg's.  Fortunately, I had an old Gasket Set with 'old material' Rope seal, but had to figure how to roll it up over the crank...Here is what I did...

Simply take a 12Pt curved wrench (also called starter, hoop, or half moon wrench, but needs to be a 12Pt) then patiently loosen the three 1'4" bolts right above the crank, but do not unscrew them too far and pry back the plate slightly. I didnt have a 12Pt so I made a wrench. You need put a slight bend on handle to clear a rear Plate Bolt at 3:00 and 9:00. (Pic below)

 Next soak the Rope Seal overnight in light Oil. (Yes, need to soak old material) then form fit the Seal in the Main Cap using a large socket or Pipe. I formed it to be .029 to start in groove then remainder was .031 - .034 depth. Next, buy a cheap Sneaky Pete Tool (Lisle #27000), use the Corkscrew provided to pull the old seal out while rotating crank, then discard the 3 tiny Lisle 'grab' attachments designed to pull the new Seal up (which wont work), and instead, insert the Lisle piano wire above the crank then hook the end of the wire into the Rope Seal as far as poss & aprx 1/4" back from Seal end. Next, start the Rope Seal into the upper groove then rotate the crank while pulling on the piano wire handle. (suggest practice with pulling the old seal around). Lastly, trim the top Seal Ends flush then place a dab of Black Permatex RTV on each end and re tighten three top bolts..

For the Cap, Fit the Seal in groove tightly and leave .015 protrude out of Cap providing a 'crush' when Cap is torqued 75 - 80lbs.

 Ive done it twice now while lying on my back with no drip.... The key thing is dont back the 1/4" screws all way out and be patient fitting the wrench on the bolts. Once get the rythm its pretty ez...This install was in Stepdown Hudson with Hydromatic.

As a Foot Note: The Best Gasket Co Graphtite Rope Seal measured .030 before fitted in Main Cap groove so probably would pull up easier over the crank. It requires pining in the Cap so elected installing N.O.S Rope.

Geoff

So you do all this from under the car, with the flywheel in place???

Ol racer

YES, I did....Actually took me longer to type process (one finger)... Shared in hopes it helps some else with annoying rear seal drip..

Geoff

Thanks muchly.   That's the next problem I have to tackle on my Hornet.

Ol racer

Attached picture showing hooking Seal to slide up over the Crank after seal compressed using Main Cap.  Note The Sneaky Pete Tool is actually reversed from theit instruction since the 'Fingers' provided slip right off.