Application Specific: Tap-Tite or Capscrews

Citroënbender · 19-10-2022, 08:15 PM

That rotten W126, but it’s a more general question about which approach is most likely to suit.

Exhibit A, the window motor and reduction gear assembly. Due to heavy loading of the system, I desire to open the housing and renew the old, dry/stiff greasing.

There’s four peened securing points holding the plate steel cover onto the cast alloy housing. To get it apart, I’ll need to counterbore them.

When re-fixing, with basic bench facilities including a Chinese drill press, is it going to be smarter (less risky) to drill for tap-tite style screws, or drill and tap? I think the thread would either be M3 or M4.

I have to process at least three motors, possibly all four; that’s 12-16 holes where failure isn’t an option.

Citroënbender · 23-10-2022, 10:19 AM

It’s the internet, ladies and gentlemen - opinions are supposed to abound.

Has anyone a thought on the best practice?

**aussiblue** · 23-10-2022, 11:55 AM

Drill them out completely and replace with flathead fully knurled shank aluminium.copper or brass rivets. This sort of thing: https://www.oukailuo.com/Customized-...-Steel-Rivets/. Try a boot maker if you can't readily source them elsewhere (I think that's where I bought my last lot) although there a plenty of ebay listings. Note the round/dome head copper ones will usually become flat headed while being driven in. Or drill through to the other side and use this type https://www.ebay.com.au/itm/37414972...Bk9SR4jnjqaAYQ or https://www.ebay.com.au/itm/35387544...Bk9SR4znjqaAYQ

prktkljokr · 23-10-2022, 12:07 PM

I know a old guy who fixes these old Mercs, he is a retired Mercedes mechanic, I actually caught him one day drilling the electric window motors and fitting a grease nipple in the housing and with the electric motor part removed he used his grease gun to refresh the grease.

Cant tell you exactly where to drill as I really was not paying attention

**aussiblue** · 23-10-2022, 12:31 PM

Quote:

I know a old guy who fixes these old Mercs, he is a retired Mercedes mechanic, I actually caught him one day drilling the electric window motors and fitting a grease nipple in the housing and with the electric motor part removed he used his grease gun to refresh the grease.

And you could always fit a temporary nipple then plug the threaded hole after greasing. Drilling a pin hole and using a grease gun needle tip would also be an option; or just using a needle tip to get through an existing case gap. . BTW Mercedes Sources https://www.youtube.com/user/Mercedessource/featured seems to suggest that bent and unlubricated window regulators arms are a bigger issues than hardened grease motors.

Citroënbender · 23-10-2022, 04:28 PM

I don’t think the regulator arm is bent, however it suffers the same grease issues as the motor. Shown here, with assisting spring near fully coiled (6mm gap to the lower bump stop is visible). There is sufficient stickiness in the grease that the spring serves no purpose throughout its arc of travel.

I could hear the motor labouring slightly when operated free of the regulator, even after I had added a scant drop of power steering fluid to the butt end porous bushing. That says to me, it won’t hurt to replace the forty year old grease in the motors.