Monday, May 13, 2013

The Road to Golf Club Fitting Nirvana: Part VII

Part I:
Part II:
Part III:
Part IV:
Part V:
Part VI:

In part VI, I assembled some of the new irons that I got from Wishon; the 575MMC model. This set is cavity back from 3-iron to the 6-iron and muscleback from the 7-iron thru the Pitching Wedge (and eventually the Gap Wedge).

First, I have had people ask why I am using Cavity Back in the 3 thru 6-irons despite being a proponent of the muscleback blade design.

The answer is that I wanted to experiment with these clubs and I figured that since my ‘Danger Zone’ (shots from 175-225 yards) clubs are the 3-iron thru the 6-iron I wanted to be able to add higher trajectory on those shots if needed. My personal philosophy is that it is generally easier to hit the ball lower when needed from a swing mechanics perspective than it is to hit the ball higher than normal. Thus, get a head design that is more suited for higher launch which is what a cavity back design does.

The 575MMC, even in cavity back, has a smaller head design than my muscleback blades 555M models. Thus it has nothing to do with ‘forgiveness’, but all to do with being able to more easily hit higher trajectory windows.

I finished up the rest of the irons (4, 5, 8 and 9-irons). Here are the main specs with regards to each iron


I highlighted a few key measurements in red. I will go over each of those highlighted, starting from left right.


One of the issues that Balance Index matching presents is regardless of what your optimal MOI Balance Index is, the longer irons will likely need a lighter shaft (conversely, short irons will need heavier shafts). If we need to raise the MOI Balance Index number, that means the shaft needs to get lighter. In the case of the 3-iron and the 4-iron, I needed to raise the MBI number.

The other issue is that MOI and Shaft Bend Profile take precedent over MBI. The shaft that had the closest Bend Profile and weighed less than the Wishon Stepless Steel shaft is True Temper’s Dynalite Gold SL


What True Temper has done is they have made a lightweight shaft with a balance point more towards the tip. This allows the shaft to be lighter without losing a lot of heft for swingweight or MOI purposes. This also makes the ball fly higher, but I am fine with that in the 3 and 4-irons.

Unfortunately, I only had one Dynalite Gold SL shaft handy. I installed it in the 4-iron and I found that the Balance Index number needed to go lower which means that I needed to add some weight to the shaft. That is as much weight I could add to the shaft with lead tape and not go over the target MOI.


I prefer to use 3/8” shaft increments instead of ½” increments. With my 555 irons, I used the 6-iron at 38” long as my baseline and went in 3/8” increments from there. However, I decided to use Wishon’s recommended 5-iron length of 38.5” based on his book 12 Myths That Could Wreck Your Game (pg. 22)

A problem occurred when I got to my 9-iron and Pitching Wedge. The total club MOI would be too high when I assembled the clubs. That is because the shafts were getting a bit too long at that point. Here are the differences between my current club lengths versus my old club lengths and ‘standard’ OEM club lengths

So had I stuck with the 3/8” increments, the 9-iron would have been 1 full inch longer than ‘standard.’ That’s a reason why the MOI was higher too high. I countered that by trimming an extra 3/8” off the butt end of the shaft and then could simply add lead tape to the shaft to get the MOI and the Balance Index where I wanted it.


Wishon’s heads have a +/- 2 gram tolerance from spec. The 3-iron came in light (I had ordered the 3-iron head over a year ago). When I was ordering the rest of the irons, I had Wishon ‘hand pick’ the heaviest 4-iron head they had on hand. Thus, they hand picked a 248.8 gram head (spec is 246 grams).

From MOI and MBI, I know that generally we have to add either a hosel weight or lead tape to the heads of the long irons. By ordering a heavy head, this just means I would not need as heavy of a hosel weight or lead tape. I will probably do the same to the 3-iron in the future.


Since the ‘shaft-grip’ combination has to generally be heavier for the shorter clubs so the clubhead feels lighter with relationship to the entire club; I tried to put the heavier grips on the shorter irons.

I use an air compressor to install my grips and it is extremely helpful for the MOI and MBI matching process. I typically put 2-wraps of blue painters tape under the grip to ‘build them up’ a little.

When I dry installed my 5-iron I found that the Balance Index was a little too low, meaning I needed a little lighter weight in the ‘shaft-grip.’ I simply used the calculator and found that if I used 1 wrap of tape instead of 2 wraps, it would reduce the tape weight by 1.1 grams and that would allow me to reach my target MBI of 38.0 to 42.0. I can hardly tell the difference in 1 less wrap of tape.


I could not get the 3-iron’s MOI and MBI within the targeted range due to the Wishon shaft being too heavy. In order to counter that, I need to either find a lighter trimmed Wishon Stepless shaft which is a completely guessing process…or install another Dynalite Gold SL shaft. However, I have hit the 3-iron very well so far outside of some occasional pulls which may be a lie angle issue.

I plan on looking at this in the future and possibly re-assembling the 3-iron.

So far I’m happy with the performance and the feel of the entire set of irons. Time will tell how the yardage gapping performs and if I feel I should try a different 3-iron. In part VIII, I will do my Hybrid.


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