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Flat FW, Saab PP, SVO disc

Uncleknucklez

bruspeed
Joined
Apr 15, 2006
Location
Sacramento, CA
Found this in an old thread, but wanted to have a chat about it with the group

buy a 6mm drill bit for $3.45 bolt the pp onto the flywheel and using the 228 thing as pattern you drill 3 holes tap in the three 6mm dowels and a flat Volvo flywheel is now a 228--with moar torquez capapcity....

This is in reference to the dowel pin location of the flat flywheel being different than the Saab PP.

Who has done this, This is my plan of attack, I dropped off my flat flywheel for a clean up at the machine shop, have a Saab Viggen PP on the way (should be here today) and a 228MM SVO 10 spline clutch disc (Clutchnet unit).

Now, I know getting the PP Centered on the FW is going to be the tough part, How critical is the operation? I feel like I can use calipers, around the edge of the PP and FW, and get the PP pretty damn centered using the bolt holes, then drill and stuff in the dowels??

What size drill bit for the 6mm dowels does everyone reckon?
 
I would take a wild guess and say a 6mm drill bit in a drill press would be the way to go.

I do know the pins have a 1? taper so test fitting or a vernier caliper would tell you what's going on there.
 
I would take a wild guess and say a 6mm drill bit in a drill press would be the way to go.

I do know the pins have a 1? taper so test fitting or a vernier caliper would tell you what's going on there.

After a bit more research, I've realized a "6mm" dowel pin actually measures slightly bigger than 6mm, I didn't know that was the case for dowel pins.

https://technifast.co.uk/recommended-hole-sizes

So, I am hunting a 6mm drill bit now.
 
Freeze the pins and gently heat the flywheel to 200f or so. Should gain enough room to drop the pin in with a nice press fit without damaging either part.
 
I use green retainer loctite for interference fit things. But it's mostly aluminum hole, steel bearing/pin, so undersized the hole by .001-.002 and heat aluminum to 220f, pin/bearing frozen to 25f and the drop right in. Steel>steel doesn't grow/shrink as much so press fit with heated part only undersized by .0005-.001 and it should go, and if you get into a pinch, overheat steel to 275f.
 
Now, I know getting the PP Centered on the FW is going to be the tough part, How critical is the operation? I feel like I can use calipers, around the edge of the PP and FW, and get the PP pretty damn centered using the bolt holes, then drill and stuff in the dowels??

Are you planning to have the assembly (FW and PP) balanced? I have a couple of these SAABie 9K Turbo 228mm PPs and the flat flywheels. I'm doubting the factory just eyeballed the PP and punched holes in it with a drill press. Being the anal OCD Engineer type, I'd "indicate the PP to center", but you will likely need a machine shop to do that, prior to dowel installation. Last time I checked, true machine dowels required a drill & reamer to hit the precise diameter (check the latest Machinery Handbook for details).

However, with all Engineer behavior aside, a good automotive machine shop should be able to install and BALANCE the assembly for you. Do it the TB way, or do it right..... you decide.
 
This is a job that needs done in a mill, either CNC or a manual machine with digital readout. Your dowel locations is critical to .001".

I did mine on our bridgeport CNC. Found center using an indicator and zeroed it out. I wrote a program to drill the pattern and pin holes. I reamed it in the mill and tapped it by hand.

After that I had the flywheel surfaced and balanced.
 
Drill bit and dowel pins... uh no. Use a reamer. If you try to use a drill it will either be too loose(fall out) or too tight(crack the flywheel). Measure the dowel with a micrometer and get a reamer that is about .002" undersize. Do it in a mill or nice drill press.
 
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