Brake Servo Adjustment

[rodo]

Bought a new servo from Vick. Very pleased with it all, good quality, but upon trying to adjust the rod that goes into the MC, I find it cannot go down far enough with the supplied nut; if I take the nut off, it goes down too far. No hope of a thinner nut as it is already tiny. Washers seemed to make sense but they are wider than the shaft and will chew up the rubber gasket (where the shaft enters the MC). Factory servo did not have a nut with the adjustment rod but it is also longer than this one. Won't work with the new servo as the old one is too thick.

I did search this site, I did find some comments, but no one seemed to actually answer what it was they did to solve this.

Vivo disegno Italiano!

[DieselSpider]

Search the brake servo/vacuum brake booster/brake lockup posts and you should find descriptions on how some could only resolve this by putting a thicker gasket between the vacuum brake booster and the master cylinder. Some of the newer replacements master cylinders along with some of the vacuum brake boosters are on the extreme end of tolerances so that the adjustment on the booster is not sufficient leaving it too long and requires some shimming with the thicker gasket.

[tima01864]

Just wondering, How far off is it from the spec. 0.030 to 0.040. My service manual had a much wider range, I went to the min.

[tima01864]

Just wondering, How far off is it from the spec. 0.030 to 0.040. My service manual had a much wider range, I went to the min.

[tima01864]

Honestly it is a difficult job getting thae vacuum booster installed and everything else with the brakes, I would send it back.

[rodo]

So the shop manual says 1.3 mm - 1.9mm. As near as I can tell the lowest I can get the rod down is about 4mm. So, a 2mm thick spacer seems not unreasonable and pretty simple. I'd like to see one, if someone has a photo.

[DieselSpider]

So the shop manual says 1.3 mm - 1.9mm. As near as I can tell the lowest I can get the rod down is about 4mm. So, a 2mm thick spacer seems not unreasonable and pretty simple. I'd like to see one, if someone has a photo.

Most just cut it from hard gasket material available at your local auto parts store. 5/64" is 2 mm so 3/32" to 1/8" would probably do to allow for a little squish.

[rodo]

So, Dieselspider, on a whim I wrote to the vendor, from whom I purchased both the servo and the mc. Told them the rod was not adjustable enough. Here is what they suggested: a dab of silicone. That sounded daft to me so I wrote back asked if they had done this. Their reply: "The silicone or some such is just to stop it trying to screw in or out. You can use thread locker such as Loctite or Elmers glue or super glue. Some people gall the threads a bit so it doesn't move without a good deal of effort. You are only trying to stop it from screwing in or out from vibration."

Am I missing something here? The rod has to push with enough pressure against the mc to activate the piston. And silicone or elmers glue is going to hold that? Wondering what you think of that.

[DieselSpider]

Sounds like they were responding to someone else who was complaining that it was not holding its adjustment and sent the message to you by mistake.

[tima01864]

If you can not meet specification the part should be rejected, In my opinion

[rodo]

Ended up calling the vendor, good guys, and talked to the wrench. Ended up using a drop of loctite on the acorn threads. Not put it back together just yet as when I went to install the plate I noticed two of the servo threads were too high. Sigh. Got out the hacksaw... Now it is on the plate and ready for me to attempt to shove it into place. I just noticed last evening that one of the thin metal "washers" on the inside of the car is just slightly askew meaning I cannot do the job myself. Anyone else ever asked their wife to climb under the steering wheel upside down to assist?

[dinghyguy]

Of course, the wife under the dash is mentioned in the manual under regular maintenance, particularly for cleaning grounds, changing bulbs without pulling cluster and installation of new speedo cables.

i have found that seat removal makes the wife much happier in these tasks. Also if you previoulsy had her getting greasy hands by helping replace the starter motor bolts, a clean activity like lying on the floor under the dash is greeted with enthusisum.
dinghyguy (and gal)

[aj81spider]

You need to be careful. Wives are only rated for a very small number of times under the dash (sometimes 0). After you exceed the rating you have to replace the wife - and that is very very expensive.

Friends, on the other hand, will grumble (although less than a wife) and can usually be brought back to specification with the application of some alcoholic lubricant.

Kids - although less effective - can be told to shut up and just do it.