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Easily available front oil seal: National 710194 - Engine & Ancilliaries/Gearbox - The Lotus Forums #ForTheOwners Jump to content


Easily available front oil seal: National 710194


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Hi All-- I am in the process of building my Lotus 907 motor to 2.4L spec with the help of Garry Kemp. I encountered a minor issue in that I could not install the provided Goetze-brand front seal. The outside diameter was a touch too large, and all efforts to press it in failed. I understand this is a relatively common issue, and sought to find a remedy in the local auto parts store. 

I turned to the Timken / National Seal catalog and identified a few potential candidate seal designs. Ultimately, I settled on the National 710194 seal (nominally 50x68x7mm), which has a double-lipped, spring-energized design. Even better, it is available at most US auto parts stores for under $12. The operational speed range is adequate (beyond 3k FPM) and the seal face design is superior to the original. The only hesitation I have is the seal material, which is Buna-N. While I don't anticipate extremely high temperatures in this part of the motor, Buna-N is only good to 250F, which leaves less of a margin than I would like. Personally, I would greatly prefer a fluoropolymer seal, but I cannot find anything available in this dimension.

The dimensions of the National seal are much closer to the original GACO INC42497 seal measurements than the Goetze seal, and mounting was proportionally easier. I used an appropriately sized aluminum disc for centering, and observed no significant deformation on installation. While I have yet to subject it to a few thousand miles of hard running, I don't anticipate any issues. 

Other solutions out there seem to be the brown TTO F3159 seal (no info available), the original GACO INC42497, in addition to the Goetze 50x68x10. GACO is now a division of Orinoco Bearings, and has yet to provide me with a quote or specifications for the seal, so it's hard to see how they stack up head-to-head.

I have included photos of the GOETZE  seal that didn't mount for comparison to the original GACO seal to highlight the issue.

 

Best,

Jake

 

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Edited by CA_Eclat
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Hi Jake.  Welcome!  Great to hear about you building a 2.4 907.  Have you left the bottom end standard, or 10-dowelled it?  Keep us posted on your progress!  I'm building a 2.5 (912, supercharged) for my Elite - slow progress!

Pete

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Peter-- I am very interested to hear how the 2.5 SC works out! I have left the bottom end standard. I had a long talk with the machinist I am working with, and opted to keep it as-is.

 

What sort of supercharger are you working with?

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Hi Jake - Because I'm converting to an auto gearbox I wanted the torque to come in at a low rpm so I'm using an Eaton M62 blower, rather than the ProCharger/Rotrex type that still needs higher rpm to perform well.  The crank will be similar to yours - fully counterweighted but slightly more throw.  CNC-ported cylinder head.  I'll be using a chargecooler - static compression ratio is 9:1, so should be OK.  I'm keeping the aircon so currently building a serpentine belt system for the a/c compressor, water pump and alternator (electric power steering, so no hydraulic pump).  Lots still to do!  I'm still trying to decide whether to 10-dowel the bottom end now I've effectively got a rev limit of 6k rpm with the auto box - not sure whether to bother.  Good fun though 😄

Pete

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