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DIY vent gauge mount

Help, Advice and DIY Tutorials on Volvo's P80 platform cars -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
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j-dawg
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DIY vent gauge mount

Post by j-dawg »

I've wanted a boost gauge for a while. The previous owner of my car had one installed in the driver's side outer vent, which I asked him to remove for some reason but soon decided I wanted back. The pod he used came from ARD, which seems no longer to sell them. A few years back I nabbed a vent grille to mount a gauge in, and with the weather being gloomy and my tie rod parts stuck in UPS limbo over the weekend, I decided to get and install a boost gauge.

I used a Bosch FST-8213 gauge because it was cheap, it has a black face and a font I liked, and it was available at the Advance Auto Parts five minutes from my house.
https://www.boschperformance.com/produc ... e-fst-8213
Dinky little thing with a Bourdon tube in it. This gauge has a 2" (52.4 mm) diameter, which is a common size for gauges, so choose whatever one you like. If you're a high roller, go for a VDO gauge - those things look so cool. I wanted a gauge I could get today for instant gratification, and those VDO units aren't cheap either.

Use a pair of tin snips or your giant angry fingers to tear out the vertical slats in the vent grille. (Needless to say, this entire process is not reversible, so do this on an extra grille if you're not sure you'll like it.)
ve come back tomorrow and ve chop off your lateral ventilation guide vanes!
ve come back tomorrow and ve chop off your lateral ventilation guide vanes!
The bracket that came with the gauge can be used to trace out a circle that you'll cut out to fit around the gauge. Note that the gauge has a bezel around the front that sits exactly on this bracket, so if we cut exactly the same hole out of our vent, the gauge will fit nicely.
i am an artist
i am an artist
Cut! I used a Dremel in a bench vise to do all the cutting, moving the vent grille against the tool. It's not easy to cut the horizontal slats - the Dremel wheel is bigger than the distance between the slots, so you have to plan your cuts carefully. I cut the control tab off the center first, then cut mostly through the middle of the slats, and finally trimmed the pieces all down to size. When you cut any of the slats in two, the half of the slat on the right will fall out of the vent grille - it's no longer held in by anything. You can see in the image below that the slats on the left side have the linkage connecting the slats together, so they will always stay parallel when installed in the grille.
slats on the left side are tied together
slats on the left side are tied together
If you're a smart, smart guy like me, you'll cut short of your marks and trim to fit. I trimmed the left side first because it was easy to work with the five slats linked together. Get the slats trimmed close enough to the gauge that you can't see any bare edges outside of the lip of the bezel. Once you get them looking like this, with the gauge seated on all five slats, stop cutting the left side and do all your adjustment on the right side. This makes it easy to see what needs to be trimmed and to do your trimming on individual slats.
left side fitted up!
left side fitted up!
Measure twice, cut once. Fitting the individual slats up is tedious, but you want all the slats to fit pretty closely to the gauge, so that the bare ends are hidden behind the gauge bezel. Grinding the edges to the right shape is important - you can see too shallow an angle on the second slat in the image below, and if I had just trimmed that back you'd see the over-trimmed corner poking out from behind the bezel in the finished product. I had to grind the corner down to the angle of the gauge to make the slat fit nicely. Take your time with this - it's by far the most tedious part of the whole process, but doing it wrong will make the finished product look bad. It's better to keep going back and forth between the grinder and the vent than to remove too much material..
bonk
bonk
With all cuts made, carefully superglue the slats in place. I did the left side first. Practice the motion of installing the slats a couple of times - you'll have to fit all five of them in quickly and precisely, since super glue is the least-forgiving adhesive ever developed. Put a drop of glue in each of the five holes and install the slats at the angle you would like them to have in the final configuration. Since it's super glue, it's going to be tacky pretty much the instant you put the slats in the hole, so give them a good push and make sure they are all the way seated. On the right side, the slats are installed individually. This is a little easier. Be quick, but be careful - you have to match the angle of each slat to that of the slats on the left, which should all be parallel to each other owing to that linkage.
What you should have now. This is actually from before I glued the slats in place.
What you should have now. This is actually from before I glued the slats in place.
Once the glue has set, give the gauge another test-fit. It's best to minimize any cutting or grinding you have to do at this point, so try to get everything fit closely before gluing.
almost there
almost there
The U-bracket that came with this mount wouldn't fit in this setup; it would interfere with the slats. So I went to Home Depot and bought a $2 20-gauge galvanized steel strip of some sort and cut out a bracket with tin snips. I bent it to fit inside the vent grille, then drilled holes in it for the mount studs on the gauge. I had originally intended to rivet the bracket to the grille, but there wasn't a lot of space for it. instead I just clamped the bracket and gauge around the springs that hold the vent grille in place, which worked great. It helped that the slats fit closely enough to basically hold the gauge on their own, though I wouldn't trust them in any sort of vibration environment.
You'll likely have to improvise a similar hack to make the gauge of your choosing fit in your vent grille. No biggie; this is all recessed a couple inches into the dash and shaded from sunlight. An ugly bracket will be pretty well-hidden from view.
precision fabrication
precision fabrication
And you're done!
it's perf
it's perf
I haven't yet hooked up the gauge to power and pneumatics, but that's the boring part, and there's plenty of guides out there for doing that. I'll probably tap into the radio harness so I don't have to hack up the factory wiring harness, and the PO had his gauge in this exact spot so I know there's gotta be a way to get a pressure tap to it.
picture apparently taken while shaking camera wildly about
picture apparently taken while shaking camera wildly about
The shiny steel strap holding the gauge into the grille wasn't too visible, but that was in the dim light of the garage, so I applied some black Rustoleum to the side of the bracket facing out. I don't think it'd be too distracting, but it was easy enough to paint it black, which should make it nearly invisible in the shade of the vent. I may wrap the radial face of the gauge body with electrical tape - it's a zinc-coated yellowy sheen, which is also not very visible, but in direct sunlight it may be more conspicuous.
glamor shot
glamor shot
And of course, as soon as I finished this up I realized it'd be 10000x cooler to put the gauge in the center vents, where everyone in the car could see it. I think that, until one glues the slats in place, one should be able to move the whole setup from one vent to another pretty easily - I bet they all use the same assembly of slats. Maybe another junkyard run is in order!
1999 V70 T5 5-SPD | ~277k mi | sold

polskamafia mjl
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Post by polskamafia mjl »

Nice work!
'All my money is gone and I have an old Volvo.' - Bamse's Turbo Underpants

Current: 1995 Volvo 850 T-5R Manual - Bringing it back from the brink of death
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sleddriver
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Post by sleddriver »

Nice cutting there and very fine attention to detail!
1998 V70 T5 226,808 miles. Original Owner.
M1 10W-30 HM

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Clemens
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Post by Clemens »

nice build Quality!
Summer: 1996 855 R
Winter: 1994 855 T5M
Donor: 1995 854 10V

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bmdubya1198
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Post by bmdubya1198 »

Very nice! Clean install, I like it!
00 V70R Venetian Red/Charcoal M56 Swapped 214k
07 XC90 V8 AWD Sport Titanium Grey/Black 220k
92 245 White/Beige 249k
91 944 Turbo 175k
…and a bunch of other stuff
Sold-
03 S60 2.4T
00 S70 GLT
98 V70 GLT
93 944
98 S90
95 850 GLT
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