sand_man

I was given an old skool VDO mechanical boost gauge with the "tattle tale" needle...the unit that fits in the clock hole. I installed the gauge by just Tee'ing of the brake booster line in the luggage compartment with a basic brass plumbing T. I DID NOT realize that there was a "gauge install kit" available from North Hollywood Speedo. This "kit" is just a hose with a special plastic T fitting that actually plugs directly into the back of the brake booster. This T looks to be a check valve of some sort.

So is this valve needed for my install? The reason for my question is that this boost gauge doesn't appear to work very well - I really have to hammer my car to get the needle to move. Either it's old and in need of calibration, or I need the special part. So far, my factory supplied tach boost gauge is keeping better track.

sand_man

Oh, and I'm aware that the tattle tale needle can effect the performance of the boosting needle.

sand_man

Or it could be that this "new" gauge is revealing a vacuum/boost leak...

OSI930

I just got my VDO boost gauge back from NHS. They adjusted the reset on the needle and checked and adjusted the calibration. Works great now and the cost was reasonable with a quick turnaround.

sand_man

I guess I could test the gauge with a Mityvac pump??

As I mentioned in another thread regarding my upcoming by-pass valve upgrade, my spool seems to be laggy. I really have to work the throttle hard to get the boost. Just doesn't seem to be building...almost like it lacks a certain sensitivity that it once had. I'll check for the obvious worn out sealing o-rings around the intercooler connections.

So I wonder if this gauge is revealing a problem? I've been suspecting that the by-pass valve assembly has been leaking/malfunctioning.

sand_man

Keep in mind the factory fitting plug on the brake booster already has a check valve on it. The one pictured above just has an extra fitting on it.

nathanUK '81 930 G50

The T you installed should be fine. That little valve that comes in the kit means you don't have to cut your hose on your car.

A930Rocket

I Teed mine into the brake booster line with out a check valve. Seems to work fine. As you said, the tell tale needle might affect it.

911rudy

Maybe now you know why you were given the gage!

sand_man

LOL! The guy who lives around the corner from me, with an '84 930 gave it to me. It was his spare. It's a cool looking gauge, though. So maybe I'll send it off to be checked out.

AngM018

It does have a really cool old school look to it though. I will definately pick one up in the future, and then have a more accurate "state of the art" eletronic one hidden out of sight.

Bernard

Where can I find one of these?

JFairman

When I got my car the clock was already replaced by a mechanical boost gauge.
Now I know why there was a perfectly good stock brake booster vacuum check valve in with the origonal clock in a plastic bag in the trunk...
cool.

kens911

north hollywood speedometer. http://www.nhspeedometer.com/ they also have the boost gauges that replace the clock, I also sent them my speedometer to calibrate and put on a 200 mph dial, and repair the odometer.

A930Rocket

Be careful with that T on the back. It breaks off easy. That's why I went the alternate route one weekend.