judson supercharger rebuild and fram bypass oil filter

Bought an oval project a few years ago and it came with a recon. engine ,gearbox and a judson.I thought the judson was brand new as every thing else was new(Pulleys,Oiler etc.)But when running was noisy but pretty much same as others i have heard.Decided to pull it apart and found out it was well, stuffed see photo.

The vanes must have worn away quite a lot, to get that sort of wear on the rotor. Maybe had the wrong [or no] oil, also.

Is that a crack between the slots? If so, the rotor's rooted.....sounds like that place in NZ.

the slots are mean't to be 3/16" wide but are well passed that.It has also been machined oversize so it is time for a new rotor.
The body is badly grooved but should hone up ok.
New rotors are available but are $700 plus postage and vanes $100. So i think first will try to make one.The vanes being oversize ,i should be able to mill these down to the right size.
I have ordered a billet of aluminium 90mm in dia.and 200mm long.
Have honed the body and has come out ok.

HappyDaze wrote:The vanes must have worn away quite a lot, to get that sort of wear on the rotor. Maybe had the wrong [or no] oil, also.

Is that a crack between the slots? If so, the rotor's rooted.....sounds like that place in NZ.

The vanes aren't worn that bad.The original rotors are quite soft,as they are a cast alloy.The rotor is not cracked but is rooted as you said.

Steve

I can not see any cracks in the rotor I have had Judsons since the early 90s in both cars

My rotors are similar in wear and have just add new vanes to make them work

Greg can you see cracks ???

new parts available from the guy in Ney York George F i can look his details up if you want

Looks like you have things under control, Steve. What grade of aluminium are you using? See if you can get a 'radius' in the bottom of the slots, when milling them.

HappyDaze wrote:Looks like you have things under control, Steve. What grade of aluminium are you using? See if you can get a 'radius' in the bottom of the slots, when milling them.

Have forgotten grade ,i went to a aluminium suppler and told him what i was going and the said this is the best grade for machining(it is not 6061 i think it was 5 something)But will be a lot better than original.

Honestly i wouldnt worry about that one Mine are similar in wear and still work Good
I have purchased a few items from George F in Ney York hes really good and easy to work with for the parts you need

What about remachining the slots and putting in spacers or thicker rotors. ??

matberry wrote:What about remachining the slots and putting in spacers or thicker rotors. ??

The slots have already been machined oversize with thicker vanes.

vw54 wrote:Honestly i wouldnt worry about that one Mine are similar in wear and still work Good
I have purchased a few items from George F in Ney York hes really good and easy to work with for the parts you need

I have also purchased parts from george.
It was working ok as you stated but iam very fussy .(It costs me a lot of money at times but it is the way i am)So i will be machining a new one or trying to.If i mess it up i will have to buy one from george.

tried to press the shaft out of rotor but it would not move.My mates 20 ton press was starting to bend.I think i will make a new shaft as this one has a few battle scars.

Its NOT meant to be removed the steel shaft has tangs on it to stop the alloy section from mooving

its cast as one piece when being made

Please ask questions before you do any more damage

vw54 wrote:Its NOT meant to be removed the steel shaft has tangs on it to stop the alloy section from mooving

its cast as one piece when being made

Please ask questions before you do any more damage

What questions do i ask? Iam going to make a new rotor and shaft because mine is worn out. Tell me how please?

Reckon you are on the right track, Steve. How will you 'key' the al. rotor to the shaft? Please show us your progress...... It will be interesting to see the results.

yes well the hard bit will be keeping the shaft n rotor together

It would be good if you could get a lump of alloy cast onto the old shaft and machine up a new rotor

Interest to know if the OD of the old rotor has varied or still concentric ( so just the slot has worn )

May be easier to mill the slot wider and obtain thicker bakelite material for the new vanes



Ive been fiddling with these since 1984 or so

Dave i am sure you have been fiddling with it since before 1984,
Mitchell

As there is very little load on the rotor,a good shrink fit should be ok.I will freeze new shaft i have made and heat rotor to as hot as i can.Then when shaft and rotor heat up should all hang together.Iam limited by my measuring equipment (have only digital calipers and my old calipers from apprenticeship) Will start for about a .005" interference fit ,which is a lot and
slowly machine shaft until it fits.Will keep you informed

vw54 wrote:yes well the hard bit will be keeping the shaft n rotor together

It would be good if you could get a lump of alloy cast onto the old shaft and machine up a new rotor

Interest to know if the OD of the old rotor has varied or still concentric ( so just the slot has worn )

May be easier to mill the slot wider and obtain thicker bakelite material for the new vanes



Ive been fiddling with these since 1984 or so

The rotor has already been machined for wider vanes.I think i have already stated that.

Hi Steve, it was nice to meet you at Warwick, will have to catch up and chat again soon.

Any pics of the new rotor and shaft??
Are you going to cut the new vein slots after pressing the shaft in?
Aaron

Steve

I take it you have seen this http://www.vwjudsonregister.org.uk/

vw54 wrote:Steve

I take it you have seen this http://www.vwjudsonregister.org.uk/

Thanks vw54 yes have read it inside out,

20bkombi wrote:Hi Steve, it was nice to meet you at Warwick, will have to catch up and chat again soon.

Any pics of the new rotor and shaft??
Are you going to cut the new vein slots after pressing the shaft in?
Aaron

Hi Aaron ,I enjoyed our chat at Warwick and it was nice to meet you.
Iam about to put up the pictures of the shaft,and hope to fit the rotor to the shaft and then machine the rotor.
Steve

Steve, I assume you have in mind some form of 'keying' of the shaft & rotor? Perhaps you could also bore the rotor under-size, to provide an interference fit. Leave the shaft in the freezer for a while, and heat the rotor in the oven [200c?] before pressing together. There are people around [Dangerous?] who could help with precise dimensions, etc.

I have made up the shaft the same specs as the sample,the thread i screw cut (last one i did was about 40 yrs ago) and fits nut like a glove.Next to bore the Rotor i made up two boring bars from 12mm and 16mm s /s i had at hand .I want them to be rigid as possible as it is a long hole.

HappyDaze wrote:Steve, I assume you have in mind some form of 'keying' of the shaft & rotor? Perhaps you could also bore the rotor under-size, to provide an interference fit. Leave the shaft in the freezer for a while, and heat the rotor in the oven [200c?] before pressing together. There are people around [Dangerous?] who could help with precise dimensions, etc.

Hi Greg,Thanks for the input,yes i will be going for a interference fit.Heat the rotor in the oven,shaft in the freezer and then heat the rotor with mapp gas to get it hotter and then if it does not fit ,remove .001" of shaft until it will fit.This may seem long winded but i have only a digatal caliper which isn't that accurate when talking .0005" Will let you know how it goes.

I tried a test cut in the old rotor to make sure it would work out ok.You can see the amount of wear .Also on the judson registry read about the case history ( i do not know how to do a link, i only learn't how to upload photo's last week).It states that the vane should be a neat fit in the slot,or air will bypass the vane and you lose effeciency .Commonsense pretty much.They will work in this state sort off,and be fine for a drive around the block but i like to know that i can drive from bris. to melb.Also in the resto of the oval the engine was rebuild to new specs. as was gearbox ,the whole car actually (it won 3 trophies at action day) So i want the supercharger to be the same.
Well onto the machining of the rotor first up was to bore a hole slightly undersize of the shaft.

Good luck with your project.

What is going to prevent the rotor from sliding/moving on the shaft when the finished product is in the Judson and actually working on the road? Just the interference fit?
Is it worth pinning the rotor to the shaft, so it cannot move in any direction?

farkengruven wrote:Good luck with your project.

What is going to prevent the rotor from sliding/moving on the shaft when the finished product is in the Judson and actually working on the road? Just the interference fit?
Is it worth pinning the rotor to the shaft, so it cannot move in any direction?

I am hoping the interference fit will be enough,if done right.There is not much of a load put on it.It is only 36hp remember,but if anyone has ideas how to pin it to the shaft let me know.Thanks for the support

A 'Scotch key' at each end of the rotor may be worth thinking about, Steve.

HappyDaze wrote:A 'Scotch key' at each end of the rotor may be worth thinking about, Steve.

Yes well done greg,butto late the shaft and rotor are one,will upload photos later all went well.To incoropate scotch keys i would have designed it slightly different ie. the shaft would have a larger centre dia. so i could drill for the pins.If this one fails i will do that.Thanks Steve

The rotor has been bored for a good interference fit.I heated the rotor in the oven as hot as it would go for 1hr & the shaft was put in the freezer for the same period.Also i heated the rotor with mapp gas but it did not quite fit 1st time round.I would hate to get it stuck half way.The rotor was put back in the oven for another 1/2 hr.and shaft in freezer.
Next time it was success as the rotor slid all the way home and instantly struck,it took another 3 hrs to cool before i could pick it up.I feel very confident that this will work ok,
but may see if i can put in a scotch key as Greg suggested.
Onto machining the outside dia. of rotor ,this is the easy part and i love machining aluminium because it is so soft and the finish is great.I will close up the tolerence a bit by making the outside dia. .5mm larger because of the wear in the body and material remove during honing.Also the end gap i will close up to .3mm it is .3 at one end and .6 at the other on the old rotor.Next will be to machine slots this will take some time as they are deep.

You are doing a fantastic job!!

I love your 'get to it' attitude.

Rotor is buggered you say? I'll just whip a new one up!!

Keep at it!



Smiley 🙂

You're spot-on there, Smiley. Steve's ignored the 'knockers', and just taken on a job that's not for the faint hearted. Pity there arn't more out there with his attitude. Good on him.👍

^^ yep, his oval is absolutely sweet as, and he did EVERYTHING himself.

Thanks guys for the encouragement it means a lot to me .Have started cutting the slots in the rotor it is slow going as i only have a small mill but so far have cut 3 without a stuff up,it would be a bastard to stuff it up now.Iam using a 3/16" thick(same thickness of new vanes) slitting saw i bought of ebay cheap ,it was blunt and would not even cut the aluminium so i made a jig on my bench grinder and sharpened it.I was going to use a end mill or slot drill originally but could not get one long enough.
First photo is tramming the rotor to get it parallel to the cutter.
Second is the slitting saw iam using

Have learn't how to put a link in (pretty slow huh) This is a good read if you own a Judson and is the reason i pulled mine apart.
http://vwjudsonregister.tripod.com/jms_case_history.htm

yep good read

the rotor is coming along great do you have new vanes

vw54 wrote:yep good read

the rotor is coming along great do you have new vanes

As they were over size vanes installed i am hoping to be able to mill them down to size as they where not too badly worn.I have researched other materials and there is far better materials available now.I will have to look back through my notes,but can remember that it was about $350 for enough material to make 4 vanes.I will be away for a few days as my wife is on holidays,weather is great so off to double island pt fishing.

I have finished machining the rotor,iam confident it will not slip on the shaft as i have a good interference fit but to be safe i have installed 2 scotch keys as Greg suggested.But instead of driving a pin in ,i have drilled and tapped 4mm grub screws with red locktight.( if i was to make another one i would make the center of the shaft a larger dia.).
Now onto machining the vanes.It was fitted with 1/4" oversize vanes and i hope to be able to machine them to 3/16" which is the standard size.

Awesome work!!...👍👍👍👍

The vanes have been machined and are a sliding fit in the slots.I will soak the vanes in Marvel Mystery Oil overnight (read somewhere to do it,plus can't hurt).
Picked up new bearings and seals from CBC today (were in stock)the old bearings and seals looked and felt ok,but new is better.All to do now is assemble which is straight forward.

Great stuff!!

WOW 🤖

Absolutley unbelievable

Brillant work 👍

Before i fitted new bearings and seals i faced off the end plates as they had a bit of scoring,this then meant i had to readjust the clearance of the rotor.This was done by machining the spacer which is shown in picture #2

Installed on car yesterday and fired her up,the difference is amazing i can actually here the motor run,before all you could hear was the supercharger making a scraping noise (i was going to take it off because i could not stand it).Can't road test which is the real test(it is not reg. as have too many regs. one day ) but should run ok as every thing is right.
Next is to make up the fittings and oil lines for the fram bypass oil filter,i know i can buy oil lines made up but I have the equipment and the time.
Thanks for the support and encouragement guys.

That's a credit to you, Steve. Nice car, too......can we see more?

Thanks Greg,Have added a few of car ,i can only attach 3 photos at a time,will have to find out how to do more at once.

Awesome work steve, might get u to make me one when the time is right..
we had a chat at valla about mmo, where in briso was it stocked again?

D-train wrote:Awesome work steve, might get u to make me one when the time is right..
we had a chat at valla about mmo, where in briso was it stocked again?

Hi,Thanks for the comments,i have been watching your build also and yours is looking good.Here's a link to the oil
http://www.skyshop.com.au/shopdisplayproducts.asp?id=305&cat=lubricants

Steve,

I'm a turner by trade and have to say I'm impressed with the quality of your work.

Good on you mate, brilliant work, if you ever need measuring equipment, give me a shout, I have it all here. Rick has my number.

Keep up the good work.

Ian

Ian 68 wrote:Steve,

I'm a turner by trade and have to say I'm impressed with the quality of your work.

Good on you mate, brilliant work, if you ever need measuring equipment, give me a shout, I have it all here. Rick has my number.

Keep up the good work.

Ian

Thanks Ian,Rick has mentioned that you have a lot of tools etc.,I will take you up on that offer and if you ever need to use a small lathe or mill , your welcome to use it.

A fram filter model no.F3-P was used on the 36 hp motors.
In keeping my oval period correct and seeing as the oval came with one .Iam going to make the fittings for it.
The oil outlet uses a t piece on the oil press. switch and returns through a hollow bolt on the dist. bracket.

In keeping period correct i don't think fittings would have been made in aluminium as most are today.So i chose 4AN size and steel 1/8" npt x4an fittings.The hoses are 4an stainless steel and came ready made at 24" long.
I machined the t piece out of hex and is 10x1 to suit oil press. gauge with 1/8npt for oil line.The return fitting i also made and it replaces the stud that holds the dissy. A 2 mm hole is drilled through and a 4AN thread was machined on one end and 8mm thread on the other.
I also made another set while i was at it and is listed in the for sale section.

so can you feel a power increase aswell? awesome job man.

DieSchnelleKafer wrote:so can you feel a power increase aswell? awesome job man.

yes you can feel the extra power,and with the stock 36hp any improvement is welcome.