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Author Topic: SD-73 Classic  (Read 10614 times)


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SD-73 Classic
« on: December 31, 1969, 06:00:00 PM »
Ball NPS Score: Not Available
The "Classic" is back. Roto Grip is proud to announce the release of the SD-73 "Classic". The ball that created the most controversy ever in the industry is back by popular demand.

The Low RG (2.50), High Differential (.075) weight block is illegal by today''s USBC standards, but since it was approved prior to the rule change it is perfectly legal for all USBC and PBA Regional competition.

The Sure Griptm solid reactive coverstock is a performance proven winner over the last several years and is still one of the highest friction coverstocks on the market today.

SD-73 Classic honor score promotion


Factory Finish  1000 Abralon  
Track Flare Potential  9+ Inches  
Lane Condition  Medium - Heavy Oil  
Cover Stock  Sure Griptm Solid Reactive  
Weight Block  High density cylinder with "flip" block  
Color  Purple  
D-Scale  73 -75  
Available Weights  12 -16 Pounds

Core Dynamics

16 lb.  2.50 (Low)  .071 (High)  
15 lb.  2.51 (Low)  .073 (High)  
14 lb.  2.57 (Low)  .051 (High)  
12-13 lb.  2.60 (High)  .032 (Med)  


Mr Scary

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Re: SD-73 Classic
« Reply #1 on: December 19, 2006, 02:45:43 PM »
15 lb. Pin next to the ring finger, and the CG kicked out a bit, one of my favorite drillings.  I did move the weight hole closer to my track to lower the flare.  Out of the box finish looked too strong, so I had it buffed.

Incredible ball.  This ball rolls SO strong.  Clears the heads great, fantastic mid-lane read, and strong backend.  This ball will clear the pins off the deck on any pocket hit, flush, high-flush, or light-flush.  Throw the big wheel, and it will turn the corner or, take your hand out of it and play up the boards, you will be impressed, and so will your opponent.  20 games old, and I already have a 300 game on it.  A must buy, maybe even 2.  I can't wait to get my T-shirt for throwing an honor score with this ball, check the Roto Grip website for information.

Chris Slagter
Roto Grip Advisory Staff
Chris Slagter
Roto Grip Amatuer Staff


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Re: SD-73 Classic
« Reply #2 on: December 21, 2006, 12:07:03 PM »
"It was legal before it was illegal", sounds like a quote from a U.S. Senator, but it is true. The .073 differential is illegal by todays USBC standards (.060 max), but is legal because the SD 73 was previously accepted under the old rule.

I drilled my 15# SD 73 in a 25 degree layout with the pin directly under my fingers on the grip centerline (5 1/4" from pap) to help the ball burn off a little energy. There was still alot leftover!
On the 39' house shot (HPL9000 synthetic lanes), the SD 73 was clean through the heads and midlane with a smooth arc to the pocket. Very little deflection through the pins on flush hits and good pin mix on the light hits.
I experimented with the surface and put a 2000 grit abralon finish on the ball and then bowled a Sr PBA Regional. The surface was wood and the pattern 44'. With the 2000 finish, the SD 73 went a bit longer but was snappier off the break point, which I did not like. I refinished it back to the 1000 abralon box finish to give me the smoother arc off the break point that I prefer.
With the cover being easily adjusted, the SD 73 should provide enough versatility for the medium to heavy oil patterns, on house and tournament conditions. Black Widow beware.....

Senor RotoGrip


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Re: SD-73 Classic
« Reply #3 on: December 24, 2006, 12:56:50 PM »
I drilled a 15 lb. with the pin 5 1/2 from my PAP, 3 1/4 above the midline, which puts the pin above my middle finger being left handed, and kicked the cg left to give me about a 1/2 positive side.

I have been struggling in one of my leagues because the shot has been very slick, I have an Epic Battle which I have to play up about 7 with, and the SD-73 allowed me to move about 10 right with my eyes and about 15 with my feet, and I had no trouble getting the ball to recover. I am very impressed with this ball so far. I only have about 6 games on it right now, but I know I will love this ball.

Rob Haverstock
 Roto Grip Pro Shop Staff


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Re: SD-73 Classic
« Reply #4 on: December 26, 2006, 04:59:15 PM »
I needed this ball to hook and control the oil.
4" Pin with MB at 45 degrees.
Problem solved.  The sure grip coverstock has been very successful with Roto Grip. Strong control with great hitting power. It's always amazing to see how easy this ball clears the front end.  I expected this ball to hook off my hand and that was not the case.   That being said, the "legal" core design is impressive.  I got exactly what I wanted, the ball really controls the mids and is pretty angular off the spot.  Much more than I expected.  I found it a little more versatile than expected, however as the lanes started to dry out the ball was much to strong due to the drilling pattern.  Cover is easily adjustable to handle a variety of conditions.  Also a little added bonus,  RG is giving away some free stuff for honor scores.  Check out the link for details.

Does any other ball manufacture do that?
Kelly O'Driscoll
Roto Grip Staff

John Brodersen

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Re: SD-73 Classic
« Reply #5 on: December 31, 2006, 06:05:09 PM »
Ball specs 15 lbs 2 oz, 3.18 oz top weight, 3.5 inch pin.

The SD-73 was drilled with a 2.5 inch pin to PAP length, 105 degree layout.  This put the pin about two inches right of, and vertically even with the ring finger.  The unmarked mass bias is located about one inch left of the thumb in the first oil ring of the ball track.  The reason for selecting this layout is as follows.  I was looking for a first ball out of the bag to be used on a heavy, fresh oil condition with fresh back ends. A ball and drill pattern that would rev up quickly, read early, and have a controlled, arcing back end reaction.  The cover was left in OOB condition.

The SD-73 provided the reaction I was looking for with an additional surprise.  The hit this ball gives is tremendous.  It also keeps the pins very low for great carry.  Even with a weaker pin position, the SD-73 provided 4 to 4.5 inches of track flare.  

For weaker handed players, punch this shell strong for oil and mediums to take advantage of the large differential.  For those of you with more hand, use weaker pin positions (longer or shorter than 3 3/8s) depending on the type of reaction you are looking for.

John Brodersen


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Re: SD-73 Classic
« Reply #6 on: January 16, 2007, 06:24:11 PM »
Lane Conditions: Medium-Heavy Oil
Typical Conditions: Tournament Shot
Type of Lane: All Synthetic
What part of the lane did you play? Second Arrow
Did the ball track out? Normal
Weight of bowling ball: 15
Surface of bowling ball: Factory/Box
What grit was the surface of the ball? 1000
Likes: If you need ball to hook and control the oil.
Problem solved.
I was amazed to see how easy this ball clears the front end
Dislikes: None at this time except:
If ball is used for other then what it was designed for.
(Too Much Ball for dry lane)

The Low RG (2.50), High Differential (.075) weight block is illegal by today's USBC standards, but since it was approved prior to the rule change it is perfectly legal for all USBC and PBA Regional competition.

The "Classic" is back. Roto Grip announce the release of the SD-73 "Classic".

The ball that created the most controversy ever in the industry is back by popular demand
If you need ball to hook and control oil.
Problem Solved.
The cover was left in Out Of Box condition
The Sure Grip solid reactive coverstock is a performance proven winner over the last several years and is still one of the highest friction cover stocks on the market today.
I was amazed to see how easy this ball clears the front end,
expected this ball to hook off my hand and that was not the case
That being said, the "LEGAL" core design is impressive
I got exactly what I wanted, midlane and angular but controlled
. The SD-73 is versatile however as the lanes started to dry out the ball was much to strong,
On heavily oiled lanes - over/under lane conditions.
Formulated to read the lanes more predictably and aggressively in heavier volumes of oil.
Cover-stock is easily adjustable to handle a variety of conditions.

After testing this ball for myself
This SD-73 will match bowlers who struggle with excessively long ball reaction.


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Re: SD-73 Classic
« Reply #7 on: February 09, 2007, 08:05:24 PM »
Before this I have never thrown a ball with this high of a diff and honestly I didn't know what to expect. My speed and rev rate are fairly high and this ball is intended to help me create angle, which is already a strong suit. I drilled the ball with the pin above my middle finger and cg swung out and had 3/8ths finger and 5/8ths side. I have never seen a ball flare this much (and I used to throw a lot of MoRich stuff known for its flare). This ball literally flared all of the way around the ball and then some (ball goes through the rack like I'm a full roller). Tons and tons of angle and surprisingly clean through the front. It was literally 2 arrows stronger than anything else I've thrown in the last 2 years. Although this is a ball that doesn't suit my game particularly well, at the very least it will be a quality conditional ball that hits like a Mack truck. This ball is a MUST have for any stroker and tweener.... Can you imagine a super accurate stroker with as much angle as a cranker? Flat scary. For the crankers, don't drill it too strong or it'll blow up at 30.

Jason Hoff
Precision Bowling Services and Roto Grip Staff Member


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Re: SD-73 Classic
« Reply #8 on: February 11, 2007, 10:21:01 PM »
Well I finally got a chance to test this ball out and watch some customers throw this ball as well. I am rather impressed with this ball. It is clean through the heads and very strong on the backend. I have mine drilled with the pin 2 inches above the ring finger and the cg kicked out toward the PAP about 6:30 or 7:00 from the pin (out of the box the pin was 4.5). I left about 3/8 positive oz side weight and a little bit of finger weight.  I got to play around with this ball on a pattern similar to the Shark PBA pattern. I was able to stand 30 and bounce the ball off 7.  While others were having to use a 500 grit abralon and go up 10, I was able to move right keep the factory finish and take some fingers out of the ball and still get it to recover consistantly.  I will give anyone reading this the same advice I give to my customers on this ball. This ball will produce a lot of backend hook. However, you need some head oil to keep it from buring out and must have some backend to get it to move. Other then that, I personally like the ball. I have a hard time finding anywhere to use this ball, but it is still one of my favorites.
Roto Grip Priority Pro Shop


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Re: SD-73 Classic
« Reply #9 on: February 24, 2007, 10:01:51 PM »
Drilled my Classic with a 4.5 " pin to pap and mb 45 degrees. Started with about 3"pin distance (to cg). With the box finish this ball rolled heavy, early and all the way --- hard. It had a tendency to burn off a little too much energy on the house patterns around my town so I put a compound shine over the box finish, which by the way, shined and smoothed this surface out in about 10 seconds on the ball spinner. Really easy to work on. I could now go around the world on the house patterns with devestation. On longer patterns I couldn't get comfortable. Too much ball to play straight and not enough shell for my tweener style to open up the lane. Maybe a differnt layout would be a better fit for me. I am impressed with the strenth of this ball and everyone I've drilled them for can't believe the boards they can cover. It wants to roll as soon as it starts smelling friction.
Cliff Saliba -Saliba's Bowlers Shop


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Re: SD-73 Classic
« Reply #10 on: March 05, 2007, 12:28:11 PM »
My ball:
16.5 MPH
400 revs
4.5" pin
pin above middle of bridge
CG kicked out about 45 degrees
Extra weight hole on PAP

.....   *
...  O.O
 .... .....    *....   O
 .... O

This is my layout, This ball and the way that I throw it needs some oil on the back or some carrydown.  It is very clean through the heads OOB but you have to put some speed on the ball or take some hand out of it and it will come back screaming!!  This ball hits hard, but the pins stay low when it does so, I think this is because of the softer shell on the ball.  I shot 15 of my first 16 strikes with it, the SD73 is very for giving and you can play almost any line as long as there is oil on the lane.
Bowling is like a fine, sexy lady, you get what you earn!!!!


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Re: SD-73 Classic
« Reply #11 on: March 26, 2007, 02:20:33 AM »
Had the SD-73 drilled with a mild set-up...2 inch pin above ring finger for use in house league shot as well as pba league shot.....As a S.Senior lefty, is easy to control...In 1st 2 weeks of Jan. shot 6-279's, plus 277-278...1st time in league had back to back 279's for 803. In house shot, could go inside 15 to 8 with long smooth back end & rips the rack.....On pba or sport condition moved out to 1st arrow with out much back-end, but still rips the rack....shot 1967 in 8 game match-play finals in Phoenix Senior Masters in Jan. for the win...Can't say enough about this ball...> A friend of mine on the east Coast who has 200 avg. wanted a ball he could use without a lot of hand & I told him about the SD73..Below is his E-mail to me after 1st night...Larry Hoffman, RotoGrip Advisory Staff.....AZ.
 March, 2007..
 Larry, Aaron and I both got the SD-73 on your advice.  I had it drilled with
 #1 drilling, for normal to slightly drier conditions.  Used last night
for the first time.  Shot 705---a consistent 235-236-234.  The ball
 went long and turned hard at the back with as powerful a finish as any ball I've had....
...Good advice. Son Aaron was just getting his drilled last
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> Campbell Soup Company
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Re: SD-73 Classic
« Reply #12 on: April 10, 2007, 11:37:08 PM »
I have just started bowling again after a 20 year lay-off.  I have an old Ebonite Thunderbolt, which is a urethane ball, but I wanted something new.  I stopped by at a local pro shop and the owner recommended 3 balls.  I actually wanted a Brunswick Radical Inferno, but he was out of stock.  He showed me a Scorchin' Inferno, a Storm Shift, and a Roto-Grip SD-73 Classic.  A friend of mine who bowls regularly and is a junior bowler coach, and his friend who is also a jb coach was there at the shop too.  There was a little debate, but all agreed that the Roto-Grip was the one to get, so I got a 15# with finger tip inserts.  The pro drilled up the ball and had me try em out at the alley, and guess what, I sucked!  What would you expect after a 20 year layoff!!  I have been practicing a bit lately and have been bowling a little more consistantly, getting my aim and marks all straight.  So far bowled a few 200+ games, and more sub 200, but hey, gotta keep practicing in order to get better right?  
Don't know much about pin and PAP, but the ball hits like a truck when you get it into the pocket.  For me, that's still the problem, finding the pocket consistantly.  The ball is aggressive, so I gotta remember not to use too much hand, or it'll run away left, not enough and it will go straight.  Miss your mark and you miss the strike.  For me, not very forgiving, but this ball makes me focus on accuracy, especially since I am a stroker with not too much revs.


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Re: SD-73 Classic
« Reply #13 on: July 25, 2007, 08:22:01 PM »
Have my SD-73 drilled 4 1/2 x 75deg with 4000 abralon, box is 1000 abralon and kinda scared me. So i took it up to 4000 abralon and kinda got a little shine on it. Not as strong as i hoped but thats ok, bc first two games with it 279-279. two ringing 10 pins on shots that should have struck , but aren't all good shots supposed to strike. Anyways, carry was phenominal and the roll was consistant. I was within 1-2 boards every shot. 1st game used my odyssey drilled at 4 1/2 x 60deg with 2000 abralon and shot 182. The house i bowl at are wood lanes w/guardian and oiled 8 to 8 42ft. Great ball.
It's not the lane nor the ball,

If you live by that motto, you'll be the man.
Brunswick and Storm are the greatest


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Re: SD-73 Classic
« Reply #14 on: April 02, 2008, 04:29:51 PM »
This ball has really helped me out in tournament play unlike any other ball in my arsenol.  In this new age of bowling where the way that tournaments are making shots harder to score on is by applying longer and heavier oil; the SD-73 helps to combat these conditions.  This is even more true for my game because I have very high ball speed which makes it harder for me to score on heavier oil patterns.  When it comes to tournament play and PBA Experience leagues this is usually the first ball I will throw during practice to get an idea of just how oily the lane condition is.  For obvious reasons this ball is pretty useless on house shot patterns, but if you are a serious bowler that enjoys competing at the highest level then there is no reason that the SD-73 Classic shouldn't be a viable option in your arsenol.
Mike Keily - Roto Grip Amateur Staff

ROTO GRIP - King Of Them All!