Sn 2000 problems

[camaro84]

Hello,

i'm christoph from austria and i'm new here and in this supercharging thematik.

I own a 1996 K1500 5,7 Vortec with an SN 2000 kit mounted. I have some problems with this Supercharger, because it won't work the way it should be. i opended the blower and did not notice any signs of wear inside. I reassembled the unit again and put in some ATF and drove the pulley with the electric drilling machine, but the impellor was moving kinda slow and stopped at a certain speed.

Can you tell me how this unit works? does the oil pressure pushes the impellor shaft towards the balls? has it anything to do with the oil pressure?
What signs of wear should i find, if there are some? I think the ball drive does not work propperly. there is to less pressure on the balls.
Are there any rebuild manuals available?

I hope anybody can help me to get this problem fixed, that i can enjoy my truck again.


thanks Christoph

[Michael]

Hi Christoph and welcome to SCH.

Sorry to hear about these problems you're experiencing with your SN2000.

From the way you've described the symptoms you're SN2000 is experiencing, it seems there isn't enough pressure being placed on on the balls within the ball drive itself. The oil has nothing to do with the pressure on the balls - it is merely there to lubricate the balls and main input shaft as they rotate. The pressure comes from the internal shims and bellevue washer within the supercharger itself. This pressure can be adjusted by adding/subtracting shims as needed, as well as increasing/decreasing the torque on the bolts holding the supercharger housing halves together.

Below is are a couple of exploded views of the ball drive system (note: the flange is omitted in the first image). Notice the shim and bellevue washer on the left side of the images; most Paxton ball drive blowers will use several shims to achieve the proper ball pressure.





Any wear that your ball drive system might have may not be visible to the naked eye. In some instances the balls themselves may just be slightly out-of-round, which would cause a problem with slipping and loss of boost, but would be impossible to detect by just looking at the balls.

Below is an official exploded view of a ball drive supercharger. It's based on an SN93 but the stated torque values should be the same for your SN2000. It's not the best quality image, but it's all there is available. I don't know of any official rebuild manual available for the ball drive blowers.



Your first step is going to be to ensure you have assembled the blower correctly and that there is sufficient pressure on the drive balls. To test for this, you will need to place a torque wrench on the input shaft and turn it. The drag should be about 25-35 in-lbs, any less and there isn't enough pressure on the balls, any more and there's too much.

Once that's set, you should also feel for any 'notching' or 'catching' during rotation; the rotation should be smooth. If there is notching or catching as you rotate the input shaft, that's a very clear indicator of a worn ball drive system, and you'll need to buy a rebuild kit to replace the balls, races, ball drive carrier, centre shaft, etc...

I hope that helps.

[camaro84]

Hi,

thanks for your replay. I think i fixed theproblem during the weekend. I put more pressure on the ball drive, with adding a thick rubber O-Ring under the thick shim. Now the balldrive drives the impeller again. Now the blower works again. How do i notice that there is too much pressure on the ball drive?

Thanks

[pavement pounde]

Hi,
Like Michael says the drag to turn the pulley should be 25-35 inch/lbs
In other words turning the pulley should be sort of heavy but at least smooth and not ratched.
The inch/lbs is pretty importand, to much and the unit will overheat and to less Makes the balls slip and wear.
Installing a rubber O-ring is not a good idea, you should use metal Shims untill the desired drag is acomplished.
Marco

[Michael]

Marco is 100% correct.

The rubber O-ring has proven my initial suspicions that there wasn't enough pressure on the ball drive, but you really should use metal shims. The amount of heat generated by the supercharger will break-down that O-ring very quickly, and the continual pressure from the bellevue washer will cause permanent rubber deformation, so you'll be back in the same situation soon. Besides, those shims are fairly inexpensive from Paradise Wheels or CUNDN Racing, so there's no reason not to do the job the 'correct' way.

And as Marco has said, the drag on the pulley is what you should use to determine whether there's too much or too little pressure on the ball drive.

[camaro84]

Hey,

thanks for your help. i didn´t thought of the heat, the blower produces. i'll change the rubber o-ring against the matal shims, i ordered at cundnracing. is there any way, to messure the right strength of the shims, so that i don't need to put one in-close the housing-try the torque-open it-put one other shim into-close the housing-try again.....methode?

should there be a gap between the two-halfs of the ball "housing"??

i saw that the thick ring (under the ball drive housing) is a little bit blue-of the heat. should i exchange this one, does this not matter?

thanks Christoph

[Michael]

Unfortunately, there's no simple way that I know of to determine how many shims you'll need. It's trial and error as you've described: assemble, check, open, add/remove shim, reassemble, check again, repeat if needed. I can tell you my SN89 has 3 metal shims. Maybe others here can chime in with how many shims they have in theirs.

I don't understand what you mean when you say "ball housing"? Do you mean the two halves of the supercharger housings or are you referring to some other parts? I've never noticed a gap between the two supercharger halves on my SN89.

The thick ring you're referring to is the Bellevue washer. It's a spring washer that adds pressure to the drive balls. If it is bluish from the heat generated, then it might be worthwhile to replace, especially given the low cost of a replacement one. I've heard of a few individuals who've replaced their regular SN Bellevue washers with one intended for a VR4 as it's a bit thicker and puts a bit more pressure on the drive balls. I'm fairly sure CUNDN sells the regular SN Bellevue washers, but you may have to call Craig @ Paradise Wheels for a VR4 Bellevue washer as I think he's the only one who sells them.

[camaro84]

Hi,

i just ordered the shims and the bellevue washer at cundn racing and i'm looking forward for the installation. I'll keep you informed.

i hope the truck runs as it should, when i'm finished. i noticed a little lag, when i pushed the throttle the last time i drove the truck. i think it must have something to do with the ignition. fixing this issue will be a little bit difficult, because there is no information about the system, i have (installation manual) at the moment. there are things like ignition controllers, adjustable ecu and things like that, which i have to check.

Does anyone know, why do i need an adjustable ignition controller for example??

Thanks

[pavement pounde]

I think you are reffering to a boost retard system, that is used for timing retard under boost, you set the know at 1 degree for example then the ignition retards timing 1 degree per psi boost.
So if you make 5 psi boost then the timing will be retarded 5 degrees.
This is to avoid engine knock also known as detonation. this is very bad under load and in boost .
Can you make some pictures so we can help some more ?
Installing a boost gauge would be helpfull to so you know how much boost you make.

[camaro84]

Hi,

Tahnks guys. I had a look and, yes it's a boost retard, what is installed in my car. My truck isn't running propperly yet, but how often do i have to adjust this switch during driving? i think i would just have to adjust this once, and then the engine is running fine ? Under which conditions do i have to readjust the ignition?

At the moment, i made a very short test ride and the engine was not spooling up, when i pushed the throttle under load. in Park position, the engine reved up fine. Does this have anything to do with this boost retard?

Thanks
Christoph

[pavement pounde]

You set it once and be done with it.
What has been done with the fuelsystem ?

[camaro84]

How do i set the boost retard? Do i need a computer for it?
It is sinstalled neer the steering wheel, so that you can easily turn the knob.

The fuel system has two extra injectors and one adjustable ECU. (I think)
Also there is a little computer connectet with the Mass Air Flow sensor.

Is there anything else, what must be installed?

[pavement pounde]

The boost retard has a knob and it displays numbers, any number stands for degrees per psi boost, so if you set it at 2 then it wil retard 2 degrees per psi boost, so 5 psi boost would be 5 times 2 = 10 degrees. set it at 1 then 1 times 5 psi boost = 5 degrees.
I have seen those adjustabel ecus, a lot of adjustabilaty, there is an explanation somewhere on the internet, do a Google search on the brand or partnumber.Place a picture of the Mass air meter little computer, I dont know what that is.

[speedytang]

Just be careful on your timing retard or when you get to a certain rpm your engine will shut down like hitting a wall under boost.

[pavement pounde]

The fuel system has two extra injectors and one adjustable ECU. (I think)
Also there is a little computer connectet with the Mass Air Flow sensor.
?

Propably it is a Paxtamap ecu also known as superfueler,
Here they sell them and they used to have an pdf download with instruktons: http://www.blowerworks.net/