British Speed Holes

British Speed Holes

"This entry is part of a Special Series on my S65 lightweight flywheel experiments as a part of my Ultimate Response Blueprint.

I’ve always been weary of lightweight flywheels and was anxious to installing this considering the labor involved.

In this entry, I examine the old, and the new: I compare the original design to the new 2022 + 2 piece design of the DCT flywheel. The MT 6spd version remains unchanged."
- Matt

The backstory. 

Back in 2020, I had discovered discussions surrounding the use of a lightened flywheel on the DCT. They were inconclusive. 

TTV was fairly unknown to most except a few European motorsport outfits.Some owners were trying to get information from a French Motorsport team to organize a group buy. 

I speak French. I organized a group buy for the DCT flywheel straight from TTV Racing, skipping the middle man. This was before EuroConnex was launched in February 2021,

How this flywheel came to be.

I started chatting with Ben at TTV Racing to better understand who they and why & how they do what they do. 

TTV Industrial has been a manufacturing group in the precision engineering and machining industry for over 30 years located in the East of England. 

A core group of enthusiasts in the family run business launched TTV Racing.They design and manufacture automotive parts for high end original equipment & motorsport, club racer to world championship.

"The first flywheel we made lapped Nürburg for 12 months before we sold any."
Ben @ TTV

The original design.

I received one of the first units from the group buy in the Spring. It shipped via DHL and got here within a matter of days. It was properly packaged. 

The original design was plain - like your run-of-the-mill platter. It was a strange thing to look at having had experiences with manual transmission flywheels.

It was light. The DCT flywheel weighted 5.8 kgs. 

TTV has 2x in-house high speed balancers to achieve proper balancing to OE specs. The balancing is done using these machined holes across the circumference of the flywheel. 

"Our flywheel spline is harder than a standard BMW spline and the same length so our product is superior to a standard flywheel spline without the nitride treatment."
Ben @ TTV

A new coating [...] led to a new design.

In late 2021, TTV started offering the first version of the flywheel with a new nitride coating. It is used a titanium, hard ceramic material applied as a vapor over metal alloy components. It hardens and protects surfaces from heat, scratches and overall wear. 

Here is how a few of the original plain designs were delivered. You can see the non homogenous aesthetics of the coating over the surface of the flywheel. 


The nitride coating is excessively expensive. TTV's concerns were about cost and requirements. The only area that benefits from the properties of nitride coatings is the hub and spline. It's where the overwhelming majority of heat is transferred between the crankshaft, flywheel and input shaft of the transmission. 

"We nitride the flywheels because a customer of ours has a forced induction cars. We thought it would be best to continue with it as a standard practice until we change the design so that only the drive hub is nitrided.

Having 1 flywheel nitrided is nearly the same price as doing 10 so makes sense to have them all done together to keep costs down for the customer."
Ben @ TTV 

The new 2 piece design. 

To achieve their cost targets, TTV used a 2 piece design they previously developed in OE contracts with Super Sport car manufacturers. They can't name drop due to NDAs.

I was able to review the latest design in-hands and experience it for myself as a local member had it fitted to his S65. 

The hub and spline can be moved within the disc. It feels alien at first - but it works. The disc and hub are now 2 pieces.

The latest DCT design retains the nitride coating on the spline. The hub is further machined for weight optimization.

The discs were further optimized for weight reduction. They feature speed holes on the flat surfaces by the circumference.  Overall, 500 grams are shaved with this new design. Less weight, more speed.

"Balancing holes are added until the flywheel is perfectly in balance, the amount of balancing holes will vary on each flywheel. The flywheel is safe past 9k."
Ben @ TTV

New hardware. 

The initial design was machined to take N55/S55 bolts. The latest design comes with bolts supplied by TTV and specifically graded for use on the S65. They retain the original BMW torquing procedures. 

It was an anxious experience buying these at the dealers in packs of 6x, when you had 9x holes. The look on SA's face when saying this went into a V8 (!).

The MT 6spd version remains unchanged!

The same design remains. It is machined to fit with the 09+ OEM clutch. The nitride coating wasn't deemed necessary on the MT. 

Up next: we get the original version fitted to my S65. 

I cover the mission critical steps to completing this installation correctly. 


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