Volumex supercharger overhaul - strip

Supercharging, turbocharging, charge cooling
Guy Croft
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Volumex supercharger overhaul - strip

Post by Guy Croft » July 8th, 2006, 5:58 pm

Step by step sequence, detailing the progressive strip of the Lancia/Fiat 'Volumex supercharger, the 'Roots' type blower used on the Lancia Beta Vx and Fiat Argenta/Spider Vx.

If you ever buy a Vx - send the blower to me for overhaul, don't try and do it yourself, this is definitely one area that requires my specialist experience. I know 'how and why' and I won't keep you waiting for weeks. These things are 26+ years old and if you say 'it sounds OK' - you might just end up with a junk blower.

I am going to have a major gripe now!
Watch out Lancia Fiat owners! There have been no replacement OE parts - gears, rotors, casings - available for these units almost since they were ever first introduced in the early 70's. Surprised? Well, they were built at Abarth and not many - I reckon just enough for the production run of cars and possibly no more than that. I have NEVER seen a new one for sale.

These blowers are super-popular for racing on vintage cars like MGs because they look just like a prewar blower. Ho ho. Unfortunately mostly they get run on amateurish crank-nose driven methanol powered instalations that lead to the total destruction the blower (and often the engine too), so they are getting very rare.
If they ever bothered to call me first I could at least tell them how to array the inlet setup and blower drive even if I don't know the first thing about methanol.
Vx blower strip 42.jpg
rear seal (there are 2 of them) vulcanised (hard) and well-past its 'sell by date'
Vx blower strip 42.jpg (12.52 KiB) Viewed 22781 times
Vx blower strip 41.jpg
using the right tool for this job is the only way to get the rear bearings out, slide hammer with expanding head, SKF.
Vx blower strip 41.jpg (23.88 KiB) Viewed 22778 times
Vx blower strip 40.jpg
heavy build up of carbon in the bearing housing betwen seal and bearing, enough of this and the rear bearings are going to seize, plus blower vents might block, allowing petrol in to the bearings.
Vx blower strip 40.jpg (25.27 KiB) Viewed 22776 times
Vx blower strip 39.jpg
rear bearing housing removed from main casing and bearing puller. The grease-packed rear bearings are a 'throwaway' item on any serious overhaul.
Vx blower strip 39.jpg (22.73 KiB) Viewed 22778 times
Vx blower strip 38.JPG
With the rear bearing bolts removed and gears off, the shafts can be slid (or gently knocked) out of the front bearings, carrying the front seal collar with them.
Vx blower strip 38.JPG (8.54 KiB) Viewed 22766 times
Vx blower strip 37.JPG
View from inner face of front gearcase, looking out, you can see the seal - just like a crankcase seal that holds the EP oil in the gearcase.
Vx blower strip 37.JPG (9.55 KiB) Viewed 22762 times
Vx blower strip 36.JPG
The front seal can be pushed you with a drift either way, there is no locating face.
Vx blower strip 36.JPG (13.16 KiB) Viewed 22760 times
Vx blower strip 35.JPG
remove the main casing vent pipes carefully - they are easily snapped
Vx blower strip 35.JPG (5.87 KiB) Viewed 22753 times
Vx blower strip 33.JPG
Front gearcase with seals and bearings removed, the small holes allow petrol vapor to vent from the main casing without contaminating the seal region and EP oil that lubricates the precious gears.
Vx blower strip 33.JPG (14.35 KiB) Viewed 22749 times
Vx blower strip 32.JPG
Carbon contamination from years of use, from backfires, reverse flow of exhaust gas, builds up behind the gearcase seals and damages them, leading to high oil consumption. The oil level must be checked every 800 miles and more often on an old engine.
Vx blower strip 32.JPG (11.47 KiB) Viewed 22752 times
Vx blower strip 31.JPG
This is an inner sleeve from one of the 4 point bearings, keep them in order and with the bearings if re-using, but if the bearings fall apart during dismantling - junk them without a second thought, or irreparable gear damage is sure to follow..
Vx blower strip 31.JPG (6.63 KiB) Viewed 22738 times
Vx blower strip 26.JPG
With the front bearings pressed out the 2 seals can be prised out, taking care not to damage the alloy housing.
Vx blower strip 26.JPG (14.11 KiB) Viewed 22738 times
Vx blower strip 24.JPG
Press the front bearings out from this side, if they fell to bits when you removed the rotors, put them back together for this op. A socket works fine as a mandrel, they are not a very tight fit.
Vx blower strip 24.JPG (18.96 KiB) Viewed 22735 times
Vx blower strip 23.JPG
Front gearcase, one bearing removed; the bearings are a 4 point contact type and very durable, save if they feel good and don't fall apart on dissassembly - a sure sign the cage is worn.
Vx blower strip 23.JPG (19.36 KiB) Viewed 22729 times
Vx blower strip 22.JPG
The only gaskets used are shown here, gearcase cover, main casing front and rear, rear bearing housing. Don't waste time making new ones, OE quality Silicon RTV will do the job just as well - if not better.
Vx blower strip 22.JPG (10.13 KiB) Viewed 22721 times
Vx blower strip 21.JPG
Rotors removed, the seal collars are grooved to create a 'labyrinth' seal to reduce the pressure acting on the seal. These collars MUST be removed from the shafts for clean & polish, they are NOT part of the rotor.
Vx blower strip 21.JPG (15.58 KiB) Viewed 22720 times
Vx blower strip 20.JPG
With the rear bearing housing removed, the front gearcase with rotors still in it (left of shot) can removed. It usually takes 'nudge' with a light hammer and suitable drift and takes the old gasket with it.
Vx blower strip 20.JPG (18.71 KiB) Viewed 22718 times
Vx blower strip 18.JPG
rear bearing housing removed, not that the rotors are still in place in the front gearcase.
Vx blower strip 18.JPG (17.95 KiB) Viewed 22710 times
Vx blower strip 14.JPG
Lock the rotors with a piece of wood and undo the bolts that secure the rear bearings, keep the bolts and washers.
Vx blower strip 14.JPG (18.41 KiB) Viewed 22707 times
Vx blower strip 17.JPG
Behind the gears is the front bearing retaining plate, here we can see the outer sleeve of one of the 4 point bearings, don't lose or get it mixed up at this stage.
Vx blower strip 17.JPG (14.28 KiB) Viewed 22707 times
Vx blower strip 16.JPG
I am always amazed how people do things DIY, but the 2 gear retaining nuts - you MUST use a 'nut gun' (heavy duty air impact wrench) for removing these, or you are going to damage something. Don't lose the 2 special washers.
Vx blower strip 16.JPG (14.37 KiB) Viewed 22703 times
Vx blower strip 13.JPG
Rear bearing cover removed, full of carbonised and contaminated grease, as I'd expect on 30 year old blower. Save the gasket if you can, discard the grease..
Vx blower strip 13.JPG (17.77 KiB) Viewed 22700 times
With the gearcase front cover removed, the two gears are exposed, they are identical. This pair? Ran the unit out of oil...all scrap, quickly.
VXgearsdamaged.JPG (14.12 KiB) Viewed 22700 times
Vx blower strip 09.JPG
Once unbolted the front cover gearcase needs a bit of persuasion to remove because the reinforced gasket holds it to the gearcase.
Vx blower strip 09.JPG (13.54 KiB) Viewed 22697 times
Vx blower strip 07.JPG
Front cover loosened, let the filthy, sulphated and carbonised old EP90 gear oil drain off..
Vx blower strip 07.JPG (16.49 KiB) Viewed 22688 times
Vx blower strip 06.JPG
Drive pulley removed. The back of the pulley runs in the front cover seal.
Vx blower strip 06.JPG (15.34 KiB) Viewed 22687 times
Vx blower strip 05.JPG
Nut, special washer (for some reason missing in this shot, see rebuild series, later) tapered collar and drive pulley.
Vx blower strip 05.JPG (15.93 KiB) Viewed 22687 times
Vx blower strip 04.JPG
Support the blower via the pulley and give a sharp strike on the shaft with a dead-blow hammer. Fit the pulley nut before striking or you may damage the shaft threads.
Vx blower strip 04.JPG (16.72 KiB) Viewed 22676 times
Vx blower strip 03.JPG
You either need an OE tool for restraining the drive pulley + very big vice + big T bar, or just a high torque 'nut gun' to get the front nut off.
Vx blower strip 03.JPG (13.56 KiB) Viewed 22665 times
Vx blower strip 02.JPG
Typical dirty old Vx unit ready to strip, remove the oil reservoir and keep safe, the unit is useless without it.
Vx blower strip 02.JPG (15.88 KiB) Viewed 22677 times
Vx unit .JPG
This is a GC built Vx race unit, the belt driven blower on right of engine produces about 6psi boost on the 2 liter TC
Vx unit .JPG (20.58 KiB) Viewed 23803 times


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