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Volumex Rotor Condition
Posted: March 13th, 2011, 6:31 am
by 037_beta
Re: Volumex Rotor Condition
Posted: March 14th, 2011, 10:54 am
by Guy Croft
Anthony, hi
you are the first to post in GC Q&A since my post re book, thank you very much for citing your book no. One benefit to me is that since we have a complete archive of who bought it I can actually find people's names which I have always prefered to use in place of site names; I often look up in member profiles but few real names are recorded. I trust that the calibre of my reply here will demonstrate my ongoing commitment to GC Q&A (albeit under a slightly tighter regime).
Sounds like some debris has gone thru this unit. The absence of the 'VOLUMEX' plate certainly suggests one of the MG mob has had his hands on it. These rather cussid little units (built by Abarth FWIW) run very tight clearances ( a few thou") rotor-rotor and rotor-casing and the rotors have to turn synchronously. The rotors are also prone to lock up and strip the drive belt teeth or even go 'out of phase' if subjected to backfire - the very thing the OE backfire valve on the inlet manifold is supposed to prevent. I would partially dismantle the blower - by this means you can inspect and dress the interior of the main casing and rotors without taking them out and losing the phasing. Hope the photo sequence tells the story.
The main casing and rotors and the inner faces of the front-rear bearing housings can be dressed using carborundun paper and Scotchbrite. Pay particular attention to the threaded areas of the casing as thread/other debris in there can wreck the rotors. Be careful at the front end of the rotors that you don't get debris trapped between the rotors and front bearing housing. A good wash with brake cleaner and airline follows.
Bear in mind that if you do a full strip you will need a special jig to phase the rotors, avoid this if you can. If the rear grease-lubricated bearings look a bit shabby and the grease too it may be that that they need to be replaced and the seals too which I can supply. I can show you what to do with that lot if need be. The rear seals are exposed to carbon and heat (and fuel) contamination and once they go hard the grease degrades. The front and rear bearing housings should carry little plastic vent pipes which allow vapour from the main casing to vent and not enter the bearing and seal regions but on every rebuild I do the venting holes and pipes are blocked and completely ineffective.
At the front end the bearings are lubricated with EP90 gear oil and seals oriented accordingly, efforts to inspect or replace the 2 seals on the rotor side of the front bearing housing will need full strip, ie: gears off. This is a whole other 'ball game'. The front cover seal (under the toothed pulley) is easy to replace and maybe should be. Minor leakage in the two behind the gears will simply cause modest ingestion of oil into the main casing which you can (I guess) cope with by checking the oil level in the special plastic reservoir. However you certainly don't want oil leaking out of the front seal.
The original build includes a gasket betw the front cover and bearing housing, apart from that the only other gasket used on build is the rear bearing housing cover (the little dished steel plate held on with 4 x M6 nuts). Both of these can be sealed with silicon or your own-made gaskets. No gaskets or sealant should be used on the main casing ends where the bearing housings bolt up.
I recommend that before hard-bolting the assembly you do a partial rebuild and make sure the rotors turn perfectly freely and in phase. M8 torque settings are 14-16lbf ft. The nose pulley torque setting is 88lbf ft.
I assume you do have the plastic vent pipes and the oil reservoir?
Hope this gets you started,
G
Re: Volumex Rotor Condition
Posted: March 16th, 2011, 4:25 pm
by Guy Croft
retrieved from the site backup, Anthony's missing post
"Thank you Guy for your thorough and considered response. I have followed your instructions and stripped the Volumex down as per your specifications. I am however missing one crucial piece of information. How do I split the casing at the pulley end (where the oil reservoir piping meets the main rotor housing) to remove the rotors from the housing? Are there any nuts or studs I need to remove to split the casing at this end? Unfortunately the Volumex unit is missing the Oil reservoir and piping with the exception of one plastic breather tube. I will contact you via email to discuss the availability of these items and the seal you recommend replacing. Do you feel that the rub marks on the rotors shown in the first sequence of photos are normal for these Volumex superchargers? The rotors are covered in carbon, with the exception of the scored metallic sections that run the length of the rotors. I will work to clean and dress the rotors as you detailed and hope that the wear is not as severe as it looks (contrasted with the carbon)."
Anthony - if you want to kindly repost your photos please do so as a reply to this
GC
Re: Volumex Rotor Condition
Posted: March 16th, 2011, 4:28 pm
by Guy Croft
Ah - once you have removed the front seal housing you can actually separate the front bearing housing from the main casing - it might need a bit of persuasion to separate the two - but as you can see below the studs fitted in the main casing go right thru the clearance holes in the front bearing housing. The studs can get corroded and tight. The main point being to get access to the rotors you slide the front bearing housing c/w rotors and gears fitted off the studs and you don't need to undo the gear retaining nuts.
G
Re: Volumex Rotor Condition
Posted: March 20th, 2011, 9:30 am
by 037_beta
Re: Volumex Rotor Condition
Posted: March 20th, 2011, 9:36 am
by 037_beta
Re: Volumex Rotor Condition
Posted: March 22nd, 2011, 9:22 am
by Guy Croft
looking good, well done!!
G
Re: Volumex Rotor Condition
Posted: March 26th, 2011, 6:48 pm
by volumetrico
Great information there !
I think this has motivated me at a minimum to check the blow off/back fire valve is working correctly on my blower !
BTW Guy, you seem to be using very good quality cadmium plated fasteners. I am having trouble finding these. Can you recommend a source for quality nuts and bolts ?
Melo
Re: Volumex Rotor Condition
Posted: March 28th, 2011, 8:38 am
by Guy Croft
I stock a vast range of metric fasteners, including stainless capscrews, bright-zinc plated nyloc nuts & capscrews, bright-zinc plated-color passivated nuts and flat washers, zinc plated spring washers of various types, bright-zinc plated and plain studs.
None of the fasteners are cadmium plated, it weakens them.
Let me know which ones you need and I will give you the price.
G