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Author Topic: SD73 Pearl  (Read 4950 times)


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SD73 Pearl
« on: December 31, 1969, 06:00:00 PM »
Ball NPS Score: Not Available has the largest selection of bowling balls
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The specifications of the SD73 are: Factory
finish: Wet Sanded 800-grit; Radius of Gyration: 2.500 (Low); Differential:
.075 (Very High); Hook Potential: 20 on a scale of 1-20; Track Flare
Potential: 9 inches; Length: 5 on a scale of 1-10; Backend: 10 on a scale of
1-10; Cover stock: Sure Grip(tm); Weight Block: High density cylinder with
"flip" block; Color: Vintage Grape: D-Scale: 73-75; Available Weights: 14-16
lbs. The specifications of the SD 73 Pearl are: Factory finish: Wet Sanded
400-grit and then polished to 2500-grit; Radius of Gyration: 2.500 (Low);
Differential: .075 (Very High); Hook Potential: 19/16 Dull/Shiny; Track
Flare Potential: 9 inches +; Length: 7 on a scale of 1-10; Backend: 10 on a
scale of 1-10; Cover stock: Sure Grip(tm) Pearl with Friction Flakes(tm);
Weight Block: High density cylinder with "flip" block; Color: Purple Pearl
with Silver MICA and White Phasing; D-Scale: 73-75; Available Weights: 14-16


Doug Sterner

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Re: SD73 Pearl
« Reply #1 on: January 05, 2001, 02:58:57 PM »
Roto Grip is a Storm product so I can throw it right ??? :-)

Wanted to try one of these "PBA Illegal" balls so I ordered up a 3-4" pin with 3.5 top weight and drilled it out.

The drilling: I drilled this one my usual drilling of 4" leverage with MB in the strong position to see what the ball would do. Weights ended up 1/2 finger, 1/2 side with 1 oz top left.

The performance: All I have to say is whew !!!! This ball was too much for me. The weightblock is way too aggressive for my game. The ball was rolling out 30 feet down the lane.Trip to the polisher...800 grit wet sand, then 1000 grit wet sand and 1000 grit Squeeky Clean to gloss. Still rolled too soon although got further downlane. Once I hit the 2000 grit polish my limited game took hold and the ball quit. The weightblock and coverstock combo was just too aggressive for my speed/rotation combination.

Although this ball didn't work well for me it works VERY well for the guy I sold it to. He has a little bit lower track than mine and also has a tad (1-2 mph) more ball speed. I moved the thumb back 1/2 inch and he was all set. The ball clears the heads well for him, starts an even roll midlane and then comes off the corner like it was shot out of a rifle.

I plan on ordering another ball and drilling it a bit less aggressively for myslef. I feel the drilling, rather than the ball, was the culprit of my bad experience.

Doug Sterner
Doug's Pro Shop
Owego, NY

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Fighting to uphold the Constitution of the U.S.

Antonio O Longalong

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Re: SD73 Pearl
« Reply #2 on: December 07, 2001, 08:21:54 AM »
I had purchased an SD73 Pearl last week.  The gross wt is 15 lbs., Top wt.- 3.36 oz. and pin placement 3"-4".  While I have carefully studied where to locate the pin and the mass bias, I did not venture to dictate  my preferred layout to our proshop driller.  Instead, I just told him that I want a smooth entry into the pin deck or a balance 'C' ball path.  I made it clear that I hate skid and sharp entry.  Our driller asked me to play a few games with my old balls and after few exchanges, he drilled the ball with the pin about 1 " to the right and " above the ring finger.  The mass bias is about 1 " from the
the thumb hole at a 4 o'clock position and a balance hole about 3 " from the  c.g. and located further right of the thumbhole.  To see an almost identical layout, visit - open Tech. Info. and proceed to Master Drilling Instruction.  Just above the Storm Xtras Surface Reaction Guide there is a drawing for Off Pap drilling. This drawing is very close to the drilling of my ball, including the location of the Balance Hole, except that my pin is located a little bit higher.

After drilling, I played one game, the first shot is a strike but the remaining shots are not impressive and I felt like I am throwing a house ball.  Our driller asked me to use the ball for a while and come back if I am not satisfied.  

The following day, I played 5 games and to my surprise I scored above 200 on 3 games. The next day, I played on another bowling center and again I scored above 200 on 3 out of 4 games.  Finally, I used it in a local league and won the 1st place on the singles event outplaying 30 other bowlers.  I scored an average of 208 in 6 games.  How else can I rate a ball that has earn me a title on its first try, except to give it 10 out 10.

For your info, I am a average rev., medium speed, semi-roller.  Prior to the SD73 Pearl, I used 14.3 lb balls.  My impression is the SD73 Pearl is like a self propelled ball, just release it with a lift and it will do the rest for you.  Do not give it a very aggressive drill or you might find it too strong.

Upon seeing the performance of the SD73 Pearl, my brother placed an order for another ball.

Our only problem now is what type of cleaning/polishing cream to use.  Rotogrip did not specify any brand that will suit their Sure Grip coverstock.  Any advice from the readers please?

Wish you all a happy bowling and merry Christmas.



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Re: SD73 Pearl
« Reply #3 on: February 13, 2002, 10:47:56 AM »
I bought this ball one year ago and WOW!!!!!!!! Is this a great ball. Not a big hooking ball like they claimed it was but a great all around ball. This was the first new ball that I had ever bought and it shows. I raised my average by 20 pins. I had the ball drilled with the pin just below and to the right of the ring finger and left the cover stock alone. On medium to dry lanes this ball would never leave pins standing. This ball is very forgiving if you miss your mark too. Then tried this ball at a different house where the lanes were oily, boy I never saw a ball go so straight I thought I was throwing plastic again. So I took a scotchbrite pad to it and look out it was a competely different ball. I shot my high series 715 and my high game 279 with this ball. This ball will always have a place in my bag.


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Re: SD73 Pearl
« Reply #4 on: October 15, 2002, 02:13:53 PM »
i just traded my eraser for this sd73 pearl with a friend of mine since i wasnt really happy with the eraser. and it was a great trade. it is drilled to go down the lane with a arc to the pocket(not aggressive, a smoooth move) i love the ball it just a nice strong arc, and it drives(never left a 10 pin or 5 pin yet. i think im a rotogrip fan now. i was into storm and dynothane

Mustang Guy

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Re: SD73 Pearl
« Reply #5 on: October 16, 2002, 09:35:50 AM »

If you like some of Roto Grips older stuff (sd73 pearl) wait tell you see the new Silver Streak Pearl they have coming out.  The Fuel has been out since July and that ball is turning heads everywhere.  If you have any questions regarding roto grip equipment let me know.  You can email me here or at

Roger Noordhoek
Director of Marketing
Storm Products, Inc.

For all your Roto Grip Logo Merchandise please visit

Roto Runner

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Re: SD73 Pearl
« Reply #6 on: February 21, 2005, 09:55:46 PM »
This ball is what makes people think they are cheating Great ball!!!!!!!
AVg. great when the lanes are on the easy side If anyone has this ball undrilled
please email      Gary Duran


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Re: SD73 Pearl
« Reply #7 on: March 18, 2005, 11:03:55 AM »
my god this it the hardest hitting ball i have thrown makes the carbide bomb liik like a pillow also they say this ball isnt a big hooking ball advise for that sian it to a 800grit finish the ball moves and tears throw oil like i have never seen very good at tackleing corner pins and gets great carry and mix when it hits light my high game with this ball as of yet is a 288 in pratice hope to get that 3 soon this ball should be in everybodys bag awsome ball

not for dry lanes