905R

[steve81]

What is the MOI / COR?

Is it .830 like everything else out there?

[Cameron Circle T]

yes you cannot have a COR any higher than .830 as that is the legal limit and the companies have perfected the technology such that they have the ability to take it right up to that limit. I cannot speak to the moi for this but if someone has just the head and can give me the mass in grams, and then measure the front to back distance, heel to toe, and top to bottom distance. i could do a general estimate on the moi using the formula.

[chien99]

yes you cannot have a COR any higher than .830 as that is the legal limit and the companies have perfected the technology such that they have the ability to take it right up to that limit. I cannot speak to the moi for this but if someone has just the head and can give me the mass in grams, and then measure the front to back distance, heel to toe, and top to bottom distance. i could do a general estimate on the moi using the formula.

 

Yeah, that will be very helpful to know the MOI for 905R head. Since I have my ideal MOI from my favorite driver 905T tour issue and now if I have the MOI of 905R head, I can very easy to make up for the rest of the parts (shaft and grip) to match my ideal MOI by copying 905T to the 905R.

 

MOI matching is more accurate than Swing weight in club hitting FEELING. My favoriate 3 driver's MOIs (905T, X-drive, R510TP) are pretty close that means if you like certain hitting feeling by referring the MOI, you can very easy to copy your ideal MOI to your new club. I would say the hitting feeling matching will be about 90% of close your ideal club.

 

chien

[BirdieBob]

For the clubhead MOI (moment of inertia):

 

"The first example refers to the MOI of the clubhead about its center of gravity. In marketing terms, this is the head design property that has a bearing on the amount of "forgiveness" a clubhead offers for off-center strikes. The larger the clubhead, and/or the more the designer incorporates perimeter weighting, the higher the MOI of the clubhead about its center of gravity vertical axis will be. The higher the MOI of the head about its vertical CG axis, the less the head will twist in response to an off-center hit, and the less distance will be lost from that off-center hit."

 

I doubt that MOI for the clubhead is really going to influence the swingweight or feel for the club.

 

"COR" is an acronym for "coefficient of restitution." Coefficient of restitution is a measurement of the energy loss or retention when two objects collide. The COR measurement is always expressed as a number between 0.000 (meaning all energy is lost in the collision) and 1.000 (which means a perfect, elastic collision in which all energy is transferred from one object to the other).

[chien99]

A very interesting finding of MOI matching from my drivers. Here is the data for your reference.

 

Club length club weight Balance point MOI COP

 

905T tour issue 45.15 332g 32 2893.6 2.9

 

X-Drive 44.75 322g 33 2872.2 2.8

 

R510 TP 45.25 311g 33.5 2847.9 2.85

 

T580 XD 45 318g 33.15 2867.4 2.8

 

R7 TP 44.50 313g 33.2 2770.8 3.14

 

COP (center of percussion)

The lower the COP the more solid the impact with the ball and greater is the energy transfer. The dimension is given in inches with the base line at the bottom of the clubhead sole.

 

With above testing data, it seems that the higher MOI, it will result lower COP by delivering greater energy transference. In practical experience of above drivers, I got pretty solid and great hitting feeling of the top three drivers in tee shot and the distance carries the most.

 

chien