17 hours ago, Derek said:

So Here is my take on conversions and why I approach it the way I do. We take an Aisin TL70 and cut a non critical part (bell housing) off of the transmission. I leverage a factory cover to give me the precision I need to make it all work. We never open the case and none of the machining I do is super critical. On the Escort conversion they weld a new bell housing onto the existing case. I have no idea the process they use but the reality is adding that kind of heat to an already machined piece is asking for trouble. The one from S30 uses a custom casting that has to be machined to the same tolerances as the original. Without knowing Asian's tolerances this can be tricky. I firmly believe this was developed for the Nismo DOHC which is configured as a reverse tilt. I'm sure the thinking was let's make it fit the standard tilt as well.

The TL70 I use utilizes a platform style shifter like the CD009. This allows me to put the shifter just about wherever I need to. This has opened it up to more vehicles. Case in point I've developed a 6 speed conversion for the Triumph TR6 and I'm starting on the MGB.

17 hours ago, Derek said:

So Here is my take on conversions and why I approach it the way I do. We take an Aisin TL70 and cut a non critical part (bell housing) off of the transmission. I leverage a factory cover to give me the precision I need to make it all work. We never open the case and none of the machining I do is super critical. On the Escort conversion they weld a new bell housing onto the existing case. I have no idea the process they use but the reality is adding that kind of heat to an already machined piece is asking for trouble. The one from S30 uses a custom casting that has to be machined to the same tolerances as the original. Without knowing Asian's tolerances this can be tricky. I firmly believe this was developed for the Nismo DOHC which is configured as a reverse tilt. I'm sure the thinking was let's make it fit the standard tilt as well.

The TL70 I use utilizes a platform style shifter like the CD009. This allows me to put the shifter just about wherever I need to. This has opened it up to more vehicles. Case in point I've developed a 6 speed conversion for the Triumph TR6 and I'm starting on the MGB.

17 hours ago, Derek said:

So Here is my take on conversions and why I approach it the way I do. We take an Aisin TL70 and cut a non critical part (bell housing) off of the transmission. I leverage a factory cover to give me the precision I need to make it all work. We never open the case and none of the machining I do is super critical. On the Escort conversion they weld a new bell housing onto the existing case. I have no idea the process they use but the reality is adding that kind of heat to an already machined piece is asking for trouble. The one from S30 uses a custom casting that has to be machined to the same tolerances as the original. Without knowing Asian's tolerances this can be tricky. I firmly believe this was developed for the Nismo DOHC which is configured as a reverse tilt. I'm sure the thinking was let's make it fit the standard tilt as well.

The TL70 I use utilizes a platform style shifter like the CD009. This allows me to put the shifter just about wherever I need to. This has opened it up to more vehicles. Case in point I've developed a 6 speed conversion for the Triumph TR6 and I'm starting on the MGB.

Derek,

I have enormous respect for you and for what you have achieved with the Datsunworks head. Precisely because I value your engineering work, I was disappointed by the way you characterised both the Escort conversion and our solution.

Your TL70 conversion is clearly a thoughtful and practical approach. Retaining the factory cover as a reference, avoiding unnecessary work inside the transmission, and using a platform-style shifter are all valid engineering choices. However, they are not the only valid engineering choices.

Welding a bellhousing to an existing case is not automatically “asking for trouble.” The quality of the result depends on the complete process: fixturing, heat control, welding sequence, material knowledge, stress management, and final inspection or machining. Shiobara-san and Escort have extensive experience, and their parts have been used successfully by many customers. A different manufacturing method should not be dismissed simply because the details of that process are not publicly known.

The same principle applies to Sagami-san’s purpose-designed casting. Accuracy depends on controlling the critical interfaces, including shaft alignment, bearing positions, transmission angle, and the connections to the engine and gearbox. These can be built into the design, precisely machined, and independently verified. The result is determined by sound engineering, machining, and inspection.

From our perspective, Sagami-san’s solution is the best solution for our intended applications, which is precisely why we chose it. That is not a theoretical judgement or a dismissal of other approaches. It is a considered engineering and commercial decision based on the complete design, its integration with the L-series platform, its construction, and our confidence in the person responsible for producing it. I have followed Nozomu Sagami’s work for many years. His knowledge and track record, including work connected with Honda Racing, Nismo, Toyota, and others, deserve serious consideration. So before we partnered we took our time to asses.

The specific characteristics of the NISMO six-speed transmission, particularly its strength and gear ratios, are also very important to us. We are considering offering the Datsunworks head as a possible option for our S30-ONE cars, and we therefore need a transmission solution that can reliably complement the performance and power potential of such an engine. For that intended application, the capabilities and gearing of the NISMO six-speed are significant factors in our decision. So I am considering having Sagami-san build an engine for us using a Datsunworks head, and I am currently discussing that project with him. I would not be considering this combination if I did not have confidence in both your work and his.

In fact, we are currently advising on a project in Australia in which JHH in Brisbane is preparing an L-series engine fitted with a DOHC head supplied by you. That engine will be connected to its transmission using a solution supplied by us and manufactured for us by  Sagami san. This is a very tangible example of how our respective work can complement each other rather than compete.

Every solution involves different compromises in manufacturing, installation, shifter placement, availability, cost, and intended application. Your approach may be the best choice for some customers; Escort’s approach may suit others. For our requirements, we believe Sagami-san’s solution is the best choice. There does not need to be one universal winner for every vehicle, customer, or application.

Thanks

Chris

2 minutes ago, christoffel said:

Derek,

I have enormous respect for you and for what you have achieved with the Datsunworks head. Precisely because I value your engineering work, I was disappointed by the way you characterised both the Escort conversion and our solution.

Your TL70 conversion is clearly a thoughtful and practical approach. Retaining the factory cover as a reference, avoiding unnecessary work inside the transmission, and using a platform-style shifter are all valid engineering choices. However, they are not the only valid engineering choices.

Welding a bellhousing to an existing case is not automatically “asking for trouble.” The quality of the result depends on the complete process: fixturing, heat control, welding sequence, material knowledge, stress management, and final inspection or machining. Shiobara-san and Escort have extensive experience, and their parts have been used successfully by many customers. A different manufacturing method should not be dismissed simply because the details of that process are not publicly known.

The same principle applies to Sagami-san’s purpose-designed casting. Accuracy depends on controlling the critical interfaces, including shaft alignment, bearing positions, transmission angle, and the connections to the engine and gearbox. These can be built into the design, precisely machined, and independently verified. The result is determined by sound engineering, machining, and inspection.

From our perspective, Sagami-san’s solution is the best solution for our intended applications, which is precisely why we chose it. That is not a theoretical judgement or a dismissal of other approaches. It is a considered engineering and commercial decision based on the complete design, its integration with the L-series platform, its construction, and our confidence in the person responsible for producing it. I have followed Nozomu Sagami’s work for many years. His knowledge and track record, including work connected with Honda Racing, Nismo, Toyota, and others, deserve serious consideration. So before we partnered we took our time to asses.

The specific characteristics of the NISMO six-speed transmission, particularly its strength and gear ratios, are also very important to us. We are considering offering the Datsunworks head as a possible option for our S30-ONE cars, and we therefore need a transmission solution that can reliably complement the performance and power potential of such an engine. For that intended application, the capabilities and gearing of the NISMO six-speed are significant factors in our decision. So I am considering having Sagami-san build an engine for us using a Datsunworks head, and I am currently discussing that project with him. I would not be considering this combination if I did not have confidence in both your work and his.

In fact, we are currently advising on a project in Australia in which JHH in Brisbane is preparing an L-series engine fitted with a DOHC head supplied by you. That engine will be connected to its NISMO 6-speed transmission using a solution supplied by us and manufactured for us by  Sagami san. This is a very tangible example of how our respective work can complement each other rather than compete.

Every solution involves different compromises in manufacturing, installation, shifter placement, availability, cost, and intended application. Your approach may be the best choice for some customers; Escort’s approach may suit others. For our requirements, we believe Sagami-san’s solution is the best choice. There does not need to be one universal winner for every vehicle, customer, or application.

Thanks

Chris

8 hours ago, Derek said:

And now a word about tolerances. If you don't know what the design tolerances are from the original manufacturer then you are playing a guessing game on what your tolerances are. If you reverse engineer something based on one sample and that sample is at the extreme end plus or minus of the allowable tolerances then your part may be out of spec and eventually fail.

Maybe Giken has access to those design tolerances. As a "long-standing Japanese engineering partner, whose decades of experience designing high-performance components for Japanese OEMs."

Still interesting that the buyer has to disassemble the transmission, removing the front case, then reassemble with the new front case. So there is some measuring and choosing of shims necessary, if it is like the previous Z transmissions. The counterbearing shim maybe. Why not just provided the completed product?

Just a curiosity. It will be interesting to see how the new Takumi Series product line grows. Maybe a complete engine is next.

p.s. the original suggestion about providing filler hose rubber has not been addressed. Seems like a real opportunity if what's out there is not of high quality. An obvious add-on to a tank purchase.

6 minutes ago, Zed Head said:

p.s. the original suggestion about providing filler hose rubber has not been addressed. Seems like a real opportunity if what's out there is not of high quality. An obvious add-on to a tank purchase.

I'm in the process of fabbing up a hardline solution from the filler through the car with a 2 1/2" ID rubber hose from the hardline to the tank. Hopefully it will be a one and done for me.

16 minutes ago, Zed Head said:

Maybe Giken has access to those design tolerances. As a "long-standing Japanese engineering partner, whose decades of experience designing high-performance components for Japanese OEMs."

Still interesting that the buyer has to disassemble the transmission, removing the front case, then reassemble with the new front case. So there is some measuring and choosing of shims necessary, if it is like the previous Z transmissions. The counterbearing shim maybe. Why not just provided the completed product?

Just a curiosity. It will be interesting to see how the new Takumi Series product line grows. Maybe a complete engine is next.

p.s. the original suggestion about providing filler hose rubber has not been addressed. Seems like a real opportunity if what's out there is not of high quality. An obvious add-on to a tank purchase.

Changing the belhousing takes about 30-45 minutes. When someone is a mechanic and follows the instructions it is a plug and play job without hassle.

There are 3 reasons to have the new belhousing apart:

-flexibility in supply line, because NISMO delivers the transmission for free directly to the port.

-we have now 2 different belhousings, for OHC and DOHC. By keeping it apart we stay flexible.

-There are people who have already a S15 gearbox and need only the belhousing.

Those things all together makes that we can offer the package at a very competitive price and stay flexible.

About the suggestion of the filler neck, we had a big stock of very good orignal ones and NOS filler necks, so for ourselves it is not a big issue.

2 hours ago, christoffel said:

About the suggestion of the filler neck, we had a big stock of very good orignal ones and NOS filler necks, so for ourselves it is not a big issue.

Are they for sale to your customers? That was my basic point. There's a need.

Anyway, good luck with the Takumi Series. It's not really a series though until there's more than one product.

So getting back to the original topic...

I fabricated a hard line that was comprised of a retaining ring at the top with a pice of 2 1/2" OD intercooler tube at a 30 degree angle. I welded in a 3/8" NPT bung that I have a .625" vent hose going to. That goes down about 10" where I have a piece of 2 1/2 ID gas filler hose that has a 45 degree bend molded in. That goes from the tube through the car to the tank.

So here is the deal. From the very first time I installed the VTS poly tank and the Resurrected Classics filler tube I have had gas fumes in the cabin. No leaks just fumes. I needed to pull the tank to make some mods to my in tank fuel pump and so I pressure tested it when I pulled it. No leaks. Made my mods and tested. No leaks. Back in the car. Gas fumes. I lived with it for months until I wanted to try a different pickup system. That brings us to now. After installing my filler neck I have zero gas fumes in the cabin. I took the old filler neck and you can literally smell gas on the outside if you put your nose up to it so I'm pretty sure that was the source of the problem.

Derek

Edited August 27Aug 27 by Derek