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The engine I'm rebuilding (Skoda Estelle/120, 70's, RWD, rear mounted engine) has a mix of different washers in its con rod bolts: some were tabbed washers, other spring washers... two or three bolts didn't have one whatsoever!

The engine was working just fine, however as I'm rebuilding it to a better state the question arises: should I only use tabbed washers for the con rod nuts, or can I use spring washers instead?

The fasteners are M8 x 1.25...the torque is to be between 18 and 20 lbs.

EDIT:

  • Tabbed washer, from catalog:

    Tabbed washer

  • Con rod nut, from catalog:

    Con rod nut

  • Parts catalog exploded view:

    Parts catalog exploded assembly

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  • I'm not really sure why it would have washers in the first place. I would think spring washers would mess with the torque (not give a true reading). I'm not really sure what a "tabbed" washer is (I believe it to be a language difference). Having anything other than a flat washer here would be foreign to me. If you could do this without washers, I think you'd be in better shape. Whatever you do, keep it consistent throughout. That would be my recommendation. M8 is a really small fastener for connecting rods I'd think! It seems to have lasted this long, I guess it will last a few more revs! :o)
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Commented May 5, 2017 at 0:03
  • Tabbed washers: those with "tabs" that once the fastened is tight you bend and hammer the tab against the bolt head/nut to avoid getting the fastener lose because rotational vibration. The original parts catalog shows them, Haynes manual doesn't...and the engine itself had a mix of washers. I need to replace the nuts, the originals are too clubbed, I would use new "regular/normal" nuts, the original have some kind of ring on the side that sits in the rod cap, like a built in separator or flat washer.
    – Aram Alvarez
    Commented May 5, 2017 at 0:34
  • Gotcha ... I wouldn't use the tabbed ones at all. Also, use Locktite on the nut to keep it in place ... never go wrong with it to hold the nut on your fastener.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Commented May 5, 2017 at 0:40
  • @Paulster2. Thanks sir. However, no Locktite in this part of the world. I need to find alternatives, ie, nail polish
    – Aram Alvarez
    Commented May 5, 2017 at 0:49
  • Well, with that in mind, I'd go with tabbed over spring washers just because it should hold it better without distorting the torque readings.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Commented May 5, 2017 at 1:05

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I would use the tabbed washers : they don't affect the torque reading as once the nut is torqued, they bend easily and just lock the nut into place. Loctite - if available - may not always be effective if the parts are not clean. Tabs work if the parts are clean or dirty.

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