Question(s) for those who've rebuilt their SN's...

[Joo]

it's easy to explain. Any difference within the various ball's production tolerances will excert a different pressure on the races. If some of the balls are smaller in diameter than others then these balls produce less pressure on the races and will turn with slippage (high temperature leads to metal fatigue). If any ball is larger then others it produces higher pressure and eventually more wear. My estimation about that.

[Charged87GTA]

yea i get what everyone is sayin, and its probably just best to go with the OE paxton balls. might just place my order today for the impeller shaft and drive balls.

just to clarify;

when i put this all together the two things that are important are the case bolts torqued to 120-160in/lbs(can be adjusted to get the right amount of torque on the impeller?)

and the torque to turn the blower 40-45in/lbs?

do i measure this at the impeller end or the pulley end?

measure this with it full of ford type f?

Anything else to look for?

[Michael]

I think getting the OE drive balls from Paradise Wheels is the smart move, especially considering this is your first attempt at servicing your SN. I'm in the same boat as yourself, and I went with a full rebuild kit from Paradise for this same reason. Maybe later, when I'm more comfortable "experimenting", then I may try different sources for parts.

I don't know if you've seen this schematic yet, but it's been posted around the forum here several times:



It states the torque values for several of the fasteners. You'll find it helpful when reassembling your SN89.

The case bolts (120-160in/lbs) are part of the means of adjustment. There are shims within the blower located between the main housing and the Belleville spring washer (item 19 in the schematic). They are what also dictate ball pressure. However in your case, since all your looking to do is replace the balls and impeller shaft, you may not need to worry about those. I'd advise tightening the case bolts to 120in/lbs first, then checking the turning torque of the blower, and retightening further if needed.

As for turning torque, I believe it's done at the impeller end... but I could very well be wrong. Hopefully someone chimes in and verifies this.

And no, I don't think you measure the turning torque with any fluid in the blower. It should be dry.

Hope that helps.

[winfred]

I lubed the balls and did all of the measuring before I pinned the upper race so it would float and show the actual pressure on the assembly, and not any misalignment in the race that would work itself out when run. measure torque at pulley

[Michael]

I lubed the balls and did all of the measuring before I pinned the upper race so it would float and show the actual pressure on the assembly, and not any misalignment in the race that would work itself out when run.

Did you do this with the seals installed or not installed? I've seen torque numbers for both with seals and without; I think the preferred method of initial assembly is without seals. But on SN92 and newer blowers, the separate oil pump/bearing assembly makes it much easier to do this; the older SN's require removal of the main shaft assembly (with all it's bearings and oil pump) in order to install the front seal once all the required shimming is determined. I can see that being a major PITA!

measure torque at pulley

I stand corrected. And now that I think about it, it makes a lot more sense than measuring at the impeller side.

[pavement pounde]

the turning torque is done at the pulley to measure the torque to drive the pulley, indeed 40-45 inch/pound.

[winfred]

I left the seals installed that i put in new 2k miles before it ate the used impeller shaft I installed when I built it the first time, got the parts from cund the first time and paridice the 2nd and the paridice stuff was the same price but better and more of it, everything including a new shaft instead of a used one, pretty much everything but the bellview washer

Did you do this with the seals installed or not installed? I've seen torque numbers for both with seals and without; I think the preferred method of initial assembly is without seals. But on SN92 and newer blowers, the separate oil pump/bearing assembly makes it much easier to do this; the older SN's require removal of the main shaft assembly (with all it's bearings and oil pump) in order to install the front seal once all the required shimming is determined. I can see that being a major PITA!



I stand corrected. And now that I think about it, it makes a lot more sense than measuring at the impeller side.

[Charged87GTA]

Alright thanks alot

ordered an impeller shaft and the drive balls today, came to 205$ 150 for the impeller, 50 for the balls and 5 to ship em

hopefully they will be in early next week

[Michael]

$205 to get your SN back up and running doesn't sound like a bad deal to me.

Make sure to keep us posted once you crack open your SN89 and tackle the ball and impeller shaft replacement.

[Charged87GTA]

lol well see if everything works out

ill keep yas posetd

thanks again for the help

[Charged87GTA]

also i got a quick off topic question

anyone ever run an intercooler with one of these blowers, would it even help much or maybe cause lag or something

[winfred]

Running a air to water on mine, not really going to incurr lag on a blower like you can on a turbo, matter of fact I had to add a second BOV to keep flutter down, one wasn't enough

also i got a quick off topic question

anyone ever run an intercooler with one of these blowers, would it even help much or maybe cause lag or something

[Michael]

also i got a quick off topic question

anyone ever run an intercooler with one of these blowers, would it even help much or maybe cause lag or something

This is a question that gets asked often in the SN section.

While running an intercooler (air-to-air or air-to-water) is certainly an option as winfrid is doing on his car, the general consensus with respect to relatively low-boost, low-flow systems (ie. 5psi-9psi; 650cfm-850cfm) an intercooler will prove to be more of a hinderance than a benefit. The added piping and volume causes the overall pressure to drop; the low airflow can't compensate for the additional volume.

For low-pressure, low-flow systems, a water/methanol injection system is considered a better option. It provides extremely effective charge cooling with no additional piping/volume or restriction to the airflow. Almost all systems today are electronic, and once they are setup, there's little continuous maintenance. The only drawback is the constant monitoring of the onboard water/methanol tank, to ensure there's an adequate supply.

Another way of helping to keep the charge air cool is to run a separate oil cooler, if you don't already have one. Paradise Wheels sells an oil cooler kit, although I know several people here have made their own versions using a B&M trans cooler. The most complex part is the oil feed/return tubing that goes where the dipstick is on a standard SN.

[winfred]

I had my system together and on the street a few days before I had the water part of the charge cooler system working and the intake temps were real high, at times it would heatsoak almost 100* over ambient, now they run 6-10* over ambient, which is good for a few hp as not nearly as much timing needs to be pulled

[Michael]

Only 6-10deg over ambient is impressive. If it's working for you, then by all means don't change a thing. My suggestion to use a water/meth system was merely mirroring what I've read on this (and other) forums.

Are you running an oil cooler as well? Did you see more boost before you had the intercooler installed?