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Rotator flexplate problem

dcm5899

Well-known member
Anybody bought a new Rotator with soft drive for a BBC and had 3 bolts between soft drive and flexplate not line up? My soft drive has two different bolt pattern diameters for some damn reason, 3 one location - 3 another. What'd you do to fix it?
 

Hotdog

Well-known member
Should have 3 inner holes and 3 outer holes they should all Lin’s up. Keep turning it. That’s how my rotator is
 

raven6947

Member
I had to drill and file 3 new holes in my engine flexplate. To do that I laid the engine flexplate on the workbench then laid the new flex drive over it. I used the 3 holes that lined up to locate and drill the other 3 holes.
 

dcm5899

Well-known member
Guess I'm drilling mine also. kind of pissed off spending $3k and having to modify engine parts that have been made the same since the early '90s to fit an oddball pattern on the gearbox
 

SWAMPHUNTER45

Well-known member
Same thing with any SFI flex plate for a Cadillac. If you use a titanium coated step drill it takes about 5 minutes to open it up enough for the bolts on the three holes. Some guys also encounter issues with the washers not laying flat due to the plates design. I have ground edges off washers making a "D" shape before or you can get a smaller washer that is the exact size of the bolts head.
 

Slidin Gator

Well-known member
SWAMPHUNTER45 said:
Same thing with any SFI flex plate for a Cadillac. If you use a titanium coated step drill it takes about 5 minutes to open it up enough for the bolts on the three holes. Some guys also encounter issues with the washers not laying flat due to the plates design. I have ground edges off washers making a "D" shape before or you can get a smaller washer that is the exact size of the bolts head.
Did it really used to require match drilling just to mate these old iron piles to a torque converter back in the day? Starting to re-think my push to get the wife to trade in her latest Hyundai for a Caddy! At least them Korean folks seem to be able to machine bolt hole patterns to line up.

Guess "Ole Rosy The Riveter" was really "Rosy The Match Driller".
 

SWAMPHUNTER45

Well-known member
The plates are made to adapt a Caddy to the Rotator or other modern GM (Chevy) pattern.

If you run the old Caddy factory plate OX BOX drives can make a direct fit FYI

Some guys back in the day would drill the factory plate but you risk a break doing that.

There is a billet flywheel Mr. Branch has had in the shop that's a direct fit no mods but very costly. He runs one of them in his truck because the tranny hits so hard it bas fractured the SFI plates. The SFI runs around $100 and is really a very simple mod to work and is good for a boat application.. With the SFI mod your only opening up the hole about an additional 1/8 of an inch if that.
 
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