Tuesday, April 23, 2013

The Road To Golf Club Fitting Nirvana - Part V

Part I: http://3jack.blogspot.com/2013/04/the-road-to-golf-club-fitting-nirvana.html
Part II: http://3jack.blogspot.com/2013/04/the-road-to-golf-club-fitting-nirvana_3.html
Part III: http://richie3jack.proboards.com/index.cgi?board=blog&action=display&thread=4180
Part IV: http://3jack.blogspot.com/2013/04/the-road-to-golf-club-fitting-nirvana_16.html

In part IV, I disassembled my 4, 5 and 6-irons. I hit my 4 and 6-irons the best and if they were graded as a ‘10’ on a scale of 1-10, my 5-iron would be an 8. When I measured the MOI Balance Index, I found that the 4-iron was at 39.6 and the 6-iron was at 40.5. So, I split the difference and made my target MBI as 40.0. However, I found that my 5-iron was at 44.66 MBI. While this is not way off, it would explain why I don’t hit it quite as well as the other 2 clubs.

For now, I’m planning to take the MBI process slowly since I’m a novice. In this part of the series, I will go over my MBI matching of my new Wishon 575MMC 7-iron (never before assembled).

I will be building myself an entire set of 575MMC’s, 3-iron thru A-Wedge. I will also be buying a new Wishon 919THI driver head and a Wishon 929HS 3-wood. I plan on doing MBI matching to all my clubs, including the standard length Edel Putter that I have.


Here are the weight measurements of my components:

Club Head: 266.9 grams

Shaft (Trimmed): 107.1 grams

Grip: 48.3 grams

Here are the initial measurements of the dry assemble:

Total Club Weight: 426.4 grams

Total Club MOI: 2,680 kg/cm^2

While the goal is to get the MOI Balance Index to match (or within 38-42 MBI); it’s more important to match the Total Club MOI and have the right shaft bend profile. I am using the Wishon Stepless Steel shafts in these irons because the bend profile works very well for me.

The software that comes with the MOI Auditor machine calculates that I will need about 5 grams of weight added to the head in order to match the MOI to my optimal MOI of 2,725 kg/cm^2. That’s fine. I have a 4-gram hosel weight. Combine that with about 1-gram for the epoxy when it cures, I should be close to being right on the money.

When I measure the club with the 4-gram hosel weight, here’s the measurements I receive:

Total Club Weight: 430.4 grams

Total Club MOI: 2,724 kg/cm^2

With Total Club MOI, there’s a range of +/- 5 kg/cm^2 that we can work with.

However, the MOI Balance Index comes out to 45.92.

That’s a bit too high as we want it under 42.0. According to the MBI spreadsheet creator, too high of a MBI will usually produce more of an inside-to-out path. Too low of a MBI will create more of a inside-to-out path.

What we know from Doppler Radar Launch Monitors like FlightScope and Trackman is that path angles tend to be very consistent. From discussing this with other clubmakers who have these launch monitors and are very knowledgable about the swing, it does not completely alter the path.

A golfer will not likely go from a rightward path to a leftward path. But, correct MBI helps produce more consistent clubface angles and if can alter the degree of the path direction. For the latter, let’s use the example of a golfer with an outside-to-in path of usually around -5°. A change in a lower MBI will not produce an inside-to-out path, but it can help them go from -5° to -3°. And with a more consistent face angle that can explain why the ball flight changes and the performance improves when the golfer is closer to their optimal MBI.


In order to get the club’s MBI from 45.92 to under 42.0; I would have to either:

1) Have a heavier shaft weight


2) Alter the balance point of the club

Or a little bit of both would happen.

This would require either a new shaft or as one clubmaker suggested; add lead tape to the shaft of the club.

The problem is that by adding lead tape you MUST account for the changes in the:

Grip + Shaft Weight
Grip + Shaft MOI
Assembled Club Balance Point
Total Club MOI
Total Club Weight

Some of those factors WILL change as you add lead tape to the shaft. The key is getting the right factors to change in order to get the MBI where you want it.

I estimated that I needed to add 2.8 gram of weight to the shaft.

FIRST, I thought that the best idea was to add the lead tape to the balance point of the club (on the shaft). My initial take was that this would essentially take care of the problem as it would not affect the balance point and would just add weight to the shaft and it would be all set.

But, there was one problem.

After I added the lead tape to the balance point section on the shaft, it increased the Total Club MOI by 10 kg/cm^2. While not a lot, I know I can feel a difference of 10 kg/cm^2 on a club having done MOI matching for almost 18 months now.

However, all is not lost. In fact, I think that since we now know that adding weight to the balance point on the shaft will add a bit of MOI to the entire club, we can utilize that information for other clubs.

Instead, I decided to put the lead tape on the shaft up near the shaft label. I was a bit skeptical of this altering the balance point.

However, it did NOT alter the balance point. My guess is that there simply was not enough weight (2.8 grams) to change the balance point. And when I re-measured the Total Club MOI it came out to 2,726 kg/cm^2; only a change of 2 kg/cm^2 and only 1 off my target MOI (2,725).

Furthermore, the MOI Balance Index changed to 41.42 which is within the range I wanted it to be:


The real test was to take it out on the range as see how it performed. I didn’t have a radar launch monitor on hand to test the differences. But, I was extremely pleased with how it performed on the range. I know I hit my 575MMC 3-iron further than my 555C 3-iron. The CoG on the clubhead is lower and the lofts are stronger and I hit it about ½ club to a full club further. I’ll have to see how the distance compares between my 7-irons.

That being said, the club felt perfect and I was amazed as to how straight I was hitting the ball. I have been working on my swing lately and seen some nice progression.

But, I don’t think I hit a shot that had more than a 2-yard draw or fade and most of them went dead straight. The trajectory was perfect. And the 575MMC’s feel of impact is exactly like Mizuno’s, so Tom Wishon came up with another great design.

And as far as the feel of the heft of the club, they just felt spot on to what works for me with the 555C 4-iron and 555M 6-iron.

I’m assuming that the 8-iron thru Attack Wedge will need more weight in the shaft. Part of this worries me because it may alter the balance point.

However, I believe that given we know that putting lead tape on the balance point will raise the MOI of the club, we can use this to find the right combination of lead tape on the balance point and adding hosel weight to match both the MOI and MBI.

That still leaves me a bit worried about the 3-iron and 4-iron when I assemble those clubs together as the Wishon Stepless Steel shaft may be too heavy. But, I can always go to the Dynamic Gold SL shaft which virtually the same profile, but is lighter.


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