Transaxle Purchase

Early on in the planning stage I needed to make a decision between a Porsche G50 or a Mendeola SDR transaxle. Those were the choices. A great deal of discussion has taken place on the Factory Five Forums regarding these options. The G50 can be had in either 5 or 6 speed configurations. There are multiple gear ratio packages and kits to make sure transaxle runs inverted.

The Mendeola was plagued in the early days with delivery problems, but those seem to be old news. There are rumors of a 6 speed version. However, the production runs have been and will be limited runs. The SDR transaxle is a market opportunity as the G50 transaxles were scooped up for various build projects.

The transaxle doesn't exist in a vacuum  There are additional parts that need to be purchased:

• Flywheel
• Clutch release components
• Stage II Clutch
• Cable shift Assy
• Pump and cooler kit
• Bolt Kit
• Gear Reduction Starter 

The additional parts cost around $5000. I built the budget based on major systems for the car. The transaxle plus these parts represent the second largest cost for the build.

Transaxle cost works out as follows:

• A properly rebuilt G50 set up for inverted use costs around $9000.
• A new Mendeola SDR costs around $11,500.

I opted to go with a new Mendeola transaxle. My feeling was that there was less to go wrong with a new transaxle than a rebuilt one. I specified a Mendeola transaxle when I ordered the chassis from Factory Five.

Then I changed my mind.

Seven forward speeds. Two more than the SDR. One or two more than the G50. Factory new (and as of this writing) on a slow boat from Germany.

One of the benefits of not having all the money up front is that I can leverage changes in technology over the three years this is going to take to complete.

Early in 2013, Eric at Gbox posted a thread on the Factory Five forums asking if anyone was interested in a 7 speed 991 transaxle. The same transaxle that is in the new generation Porache 911.

My neck still smarts from the whiplash. Say what!?! Brand new, shipped from Germany, 7 speed Porsche transaxle!!!!

Good bye G50.

Good bye SDR.

Hello 991!

I am bouncing off the walls.

Gbox puts all the parts together and test beds it on an LS block before it leaves their shop for the Northern Man Cave. It is a brand new transaxle that is currently shipping in the 991 generation of the flagship Porsche 911s.

The bad news is this busts the budget. The 991 costs $13,500. Ouch!

Or does it?

One of the items high on the design list were paddle shifters. I contacted Master Shift (my vendor for the aftermarket paddle shift solution) and asked if they had done anything with a 991 transaxle. The answer was no. They had done a 7 speed pattern for a different transmission. I chewed on this for a  couple of weeks. I decided that I did not want to be the Mark I version for an aftermarket paddle shift solution. With great reluctance, I dropped the paddle shifter from the design plan and gained $3000 back to the budget.

The SDR option has the following costs:

• SDR - $11,500
• Additional Parts - $5000
• Paddle shifter = $3000
• Total cost is $19,500 plus shipping

The 991 option has the following costs:

• 991 - $13,500
• Additional Parts - $5000
• Total cost is $18,500 plus shipping

By dropping back to tradition bump shift and going with the 991. I am $1000 below the cost of a new SDR with paddle shift. This isn't funny money like what happens in Washington. This is my pocket book.

Originally, I had hoped to do the engine and transaxle in 2013. That is no longer going to happen. My concentration this year is the rest of the car and the transaxle.

As my wife's cousin said, "Someone is going to have some fun!"

I certainly am!

Mount Master and power Cells

<< ISIS Wiring Digram                                             Finalize ISIS Schematic >>

Major System Category: ISIS Wiring
Task: Mount basic 3 cell kit
Parts: 1 Master Cell, 2 Power Cells
Prerequisite Tasks:
Additional Costs: $1000 (Ebay Purchase)
                              $1032 (Isis purchase 2 x Power Cells)
Time Requirement: 3 hours
Date Started: December 03, 2012
Date Completed:  December 05, 2012

I am installing the ISIS power system. Basically, this replaces the Painless wiring block and harness. I have designed the car to handle up to 50 circuits. I currently think this will consist of four power cells and one motion cell. Prices on the ISIS system went up dramatically since I put my budget together. The seller was Zcars Limited in the United Kingdom. They were reasonable folks to deal with, and we quickly came to an agreed price.

Two power cells, one master cell with RF controller installed and two fobs for the RF controller. (Yes, that's a magazine for a Glock 17 next to the master cell. It's a multifunctional work bench.)

After a couple of days, the three cell basic kit plus the inLink RF control module arrived. Shipping was free, but Uncle Sugar imposed a customs duty on the purchase.

This is the bus cable that connects the two power cells to the master cell. the bus cable  sends data signals from the inputs (received by the master cell) to the correct power cell (where components are attached). The longest run I had was from cell #1 to cell #2. It had to traverse the length of the car through the tunnel. The power cells are are identified by a 4 bit binary address (i.e. 1 - 16) that is hard strapped to the power cell.

Now that I had the basic ISIS components, it was time to make some decisions: where and how do I plan to mount the cells. The three cell kit has some basic criteria:

1. Cell #1 for forward components.
2. Cell #2 for rear components.
3. Master cell somewhere in between.

I really didn't come up with these mounting solutions. They represent the best of what I have found on other builder sites. Before I ordered the car, I purchased ISIS mounting plates from Vraptor Speedworks. I used two of these mounting plates for the master cell and power cell #2.

There is nothing fancy about these hinges. They are a $2 part from Home Depot. I simply riveted them in place, and made sure I didn't interfere with the master cell. This is the Vraptor master cell mounting plate. I have it clamped in my dad's old vice (a chunk of iron much older than me).

I attached a hinge to the master cell plate and mounted it under the passenger side dash. This way, I can release a latch (still needs to be built) and drop the master cell down to a visible spot.

Master cell mounted on the passenger side. It will fold up under the dash. Not pictured here is a conduit (2.5 inch PVC pipe) that runs across the top of the Vintage Air HVAC unit. I plan to run the necessary inputs through that conduit as required. Those cables plug into the top and bottom of the master cell. The AC blower motor is wrapped in yellow plastic behind the master cell. Orientation: Looking towards the passenger side foot well.

Power Cell #1 is mounted on the middle aluminum panel under the hood and above the radiator cooling fans. I plan to mount Power cell #3 and the inMotion cell there as well.

Power cell #2 is mounted on a Vraptor plate and the plate is mounted to the  tubular chassis. Orientation: Engine bay pointing towards passenger side. You can see the rear tire right hand side of photo. 

Power Cell #2 is mounted on the passenger side close to the hatch hinge. I made sure I left enough room for the ECU mount. This is on the side opposite the fuel filter/fuel pump installation.

Megafuse panel fabricate from angle aluminum and a aluminum sheet. This can be readily purchased at Lowes or Home Depot. I used the megafuse holder as my template to drill holes.

The other mounting issue relates to the megafuses. Each power cell is protected by a pair of megafuses. The megafuses connect to the battery and/or the inReserve module. To facilitate this I created a fuse panel that I can attach to the back side of the middle panel where I mount the majority of the power cells. This places the megafuses in close proximity to the battery.

Megafuse panel with fuses mounted for power cells #1 and #2. I had to trim the lower left  hand corner to get it to fit properly into place with the chassis.

I designed the megafuse panel to be removable so it is easier to work with. I attached an angle aluminum piece the length of the fuse panel to the back side (battery side) of the middle panel. Then I drilled holes in both the fuse panel angle aluminum and the middle panel angle aluminum large enough for plastic push rivets. This ends up being a very secure piece.

The fuse panel is attached to the back side of the middle panel. The three black buttons are the push rivets to secure the top of the panel in place. The megafuses are next tot he AC condenser (yes, it is very crowded in here). The data bus cables are snaking over the top of the panel. This where I had to cut the channel (not pictured here). The yellow connector is where the data bus cable connects to power cell #1. Orientation: Looking forward under the hood.

The issue I did not foresee until I lowered the hood was the interference between the inside of the hood and hood louvers with the middle panel. I ended up cutting a channel for the data cable and power connectors. I still have to create a latch to hold these down when the hood is closed.

The last thing to do is connect the red power cables into the megafuses. I gave the cables slack . Hopefully, nothing gets upset long term.

The power cables for for power cell #1 were relatively short, because I just had to snake them over the fuse panel. I decided to run the power leads for power cell #2 inside the channel formed by the body shell and the bottom of the chassis where the passenger door resides. This keeps the power leads away from the engine headers. However, I had to extend the power leads by 18 inches so they would reach the megafuses.

UPDATE:
I purchased the rest of the set up from ISIS in the last quarter of 2013. The nice thing about this product is that you can add to it as you go. The addition components were 2 power cells and 1 InMotion cell. The InMotion cell is a somewhat different creature, so I am going to handle that in separate post.

These are power cells 4, 3 and 1 (left to right) mounted under the hood.

I mounted power cells #3 and #4 next to power cell #1. This required that I run the data cable from power cell #2 to power cell #3. I ended up about 30 inches short. However, I had a very short run from power cell #3 to power cell #4. So I cut out the middle of one data cable for the short run and spliced in what I needed for the longer run. I didn't have to purchase any additional components to get to this point.

This is the megafuse panel on the other side of the power cells. The panel is currently mounted, because I am waiting on the bus bar to connect everything. However, everything fit - even though I fabricated this panel last December!

The panel I fabricated for the megafuses worked as designed. The one thing I was missing was a copper bus bar to connect all megafuses from a single power lead. The great thing about Isis Power is you can email them a question and get an answer the same day. Jay sent me a link to the vendor they used for the copper bus bars. I ordered a a strip. The beauty of this is, I completed the entire transaction without wandering off somewhere.

Aluminum Tanks

<< Rear Quarter Floor (R, L)             Fuel Tank Crossover Tube >>

Major System Category: Fuel System
Task: Install Aluminum Tanks
Parts: Aluminum Tanks
Prerequisite Tasks: Rear Tunnel Aluminum
Additional Costs: $1200
Time Requirement: 3 hours
Date Started: October 6, 2012
Date Completed: October 6, 2012
Sometime in mid-August, I started working on the Corvette tank modifications. The further I progressed on this task, the more obvious it became that there was no way this was a good idea. First The driver's side tank becomes the passenger, then the manual instructs that holes be drilling into the bottom of both tanks. The specified hole turns out to be larger than the supplied AN fittings. Plus, I realized I had just created the weak link in a fuel system running at 50 PSI.

Quick Racing Products aluminum tanks.

I test mounted the Corvette tanks, raised the lift and read further in the build manual. Based on my understanding, the plan was to run a fuel line between the tanks right in front of the engine. Indeed, this is something that needs to happen, but seemed really close to where the accessories are going to be spinning. I stood there under the car looking from the manual to the car, and slowly it began to penetrate my rather thick skull, why one poster on the FF forums said the Quick Racing Products tanks are a must have.

Black silicone applied to the 2x4 blocks.

There are enough threads from people who have had fuel tank leak issues. Remember, my chassis is number 402. According to the Stewart Transport driver, he is delivering approximately 10 GTMs per year. Only half of these (Gen I and II) are complete. So if a significant number in that population write about fuel leak or heat problems, I need to listen. To balance this, there are GTM owners that have followed the build manual recommendations and do not have leaks. Then there was the guy who went that route, and after some 5 or 6k miles, his tanks started leaking. He has had to tear half the car apart to fix this problem (not a happy camper).

Camper mount tape applied to the chassis members that contact the fuel tanks.  The wood blocks also have tape applied and sit inside the rear quarter pan behind the fire wall. Orientation: Looking towards the rear of the vehicle where the fuel tanks reside from the driver's cockpit.

So I sat down with the budget spreadsheet. Aluminum tanks and the corresponding fuel pumps were not in the budget. I pushed back the ISIS power purchase (maybe into 2013), bit the bullet and ordered the tanks and fuel pumps and all the plumbing needed to make it work. I decided the a fuel leak in an area where fumes can accumulate next to a hot engine in a high performance sports car is not a good thing. Yes, I am spending a lot of time building this car (and having a blast doing it), but I also want to spend some time driving her when she's finished.

This is the cut out in the tunnel wall. I took the measurements from the template and ran lines. Then I test mounted the  fuel tanks, and figured where I needed a tad more room. Finally, I sanded and deburred the openings. Orientation: Facing rear tunnel from driver's cockpit.

Ron and Ted are the two guys on the other end of the phone when you talk or write to Quick Racing Products. I've never put a fuel system in before. Both of them were willing to take the time to answer my questions. They also knew what I needed when I gave them the engine specs. While this isn't a turn key, drop in solution, I feel better about not drilling holes into perfectly good fuel tanks.

Fuel tanks installed. The driver's side tank is closest. It is a bit harder to make out  the passenger side  tank. I applied camper mount tape to the back of the tank as well. This is where the fire wall makes contact with the fuel tanks.

The installation process is straight forward.

1. Install the floor plates (thank goodness for lift!)
2. Cut 4 1 foot sections of 2 x 4. (My buddy Vern cut me a 2 x 4 a couple of weeks ago, who knew that half of it would end up inside the car!)    
3. Apply black silicon to the underside of the wood. The tanks sit on top of the wood.
4. Apply camper mount tape to the contact points (on the chassis) where the tanks make contact.
5. Cut out a section (per the supplied template) in the tunnel wall. (This part of the tunnel was already installed. Be careful not to cut through a brake or clutch line.)

This is the passenger side tank fitting for the cross over pipe that runs between tanks. This is a good 12 inches further back into the tunnel and away from the engine.

I test mounted the new tanks a couple times. Everything seems to fit okay. I'm just waiting on the fuel pump and related supplies to show up next.

Budget Review - End of Planning Phase

Yesterday, I placed the order for the GTM. It should show up some time in mid June. This essentially ends the planning phase of the build. The kit purchase is the single largest line item of the entire build. So I think it is a good time to review the budget. My initial estimate was $68,200. When I refined this number, I came up with  $72,200. I set the budget at $70,000. My projected cost is currently 20% higher than that. So where did I go wrong, and importantly, why did I go wrong.

I think it is still possible to build the GTM for something between $55,000 and $60,000. This means you are making no upgrades, and use everything from a donor, including the engine and a recondition Porsche G50 transmission. There is nothing wrong this approach, but I wanted something better. If I'm going to pour three years into this project, then I want a car at the end of this project that is unique and tailored to my specifications.

The following chart shows expenditures to date, based on my original estimate ($70,000), adjustments to specific line items, actual costs and variance to the adjusted line estimates. I have actually done very well to date. I am well within my estimates. I think these categories are easier to price.

Item	Estimate	Adjusted estimate	Actual	Variance
brakes	2000	2000	1945	55
donor	11000	11000	4649.02	6350.98
wheels	3200	3200	1380.99	1819.01
Kit	25000	22967	22692	275
Totals	41200	39167	30667.01	8499.99
Pct of original Estimate	58.86	55.95	43.81
Pct of Revised Estimate	50.24	47.76	37.4

I saved money by going with a donor parts kit, and I haven't purchased the Nitto Invo tires.

Technology and add ons have increased the cost. Yes, mission creep has struck!

These are the categories where I blew the budget estimate:

Item	Estimate	Adjusted estimate
ISIS	0	3108
harness	1500	0
Paint	3000	9000
options & add ons	4000	7714

When I started this project, I didn't even know that ISIS power existed. Sometime last fall I came to realize ISIS was the only sensible power system for the GTM. It provides a programmable and scalable power management system.

The engine harness fits nicely with the engine budget. I think I'm within 10% of both the original transmission and engine estimates. The current engine  slated to drop into the GTM is a LS376/525 with electronic fuel injection. I think it will be relatively simple to get this to just under 600 HP with the optional cold air intake (part of the kit order) and the Kooks custom exhaust (part of the options).

I had no idea how much the paint job would cost and I plugged a number in. I was way off. 

The real mission creep is in the options and add ons section. 

• There are a bunch of body work pieces that I will order from Vraptor Speed Works.
• The paddle shift system to replace the conventional shifter in the center console. This is to make room for additional electronics and ISIS hardware.
• The Ram Lift system to protect the GTM body from unsightly scrapes and damage.
• One thing not reflected at the moment is the APR Racing Wing and mounting hardware. This is an enhancement that is not required to complete the car and can be added at a later date. So I have not reflected this in any of the budget figures.

My conclusions for the over budget issue. The GTM is a work in progress and the build is stretched over 3 years. Technology and ways to do things better will present themselves through out the build. If this were a 3 month project and I had all the money up front, then line items would be cast in stone. Due to the length of the build and the nature of the car, it is foolish to ignore technological innovations that will enhance the finished product. Obviously, I should have included a bigger number for the options and add ons.

Mendeola SDR-5

I had a chance to check on the Mendeola SDR-5 transaxle. This is the transaxle designed for the GTM. Mendeola has a online catalog that is populated with photos of the GTM and Superlite SLC. They state that the SDR-5 was "Based on a mid-engine 2 seat, 2 wheel drive sports car with a wheelbase between 92" and 102" which weighs between 2400 and 2800 lbs. Front to rear bias: 45%F - 55%R. Rear tires P295 - P325 on 18" or 19" wheel."

Mendeola SDR5 transaxle. This was designed for the GTM.

Sounds like a GTM to me! There have been a lot of numbers thrown around about the SDR-5 transmission. These are the published numbers from Mendeola:

• 650 horsepower
• 600 foot-lbs torque

The knock on Mendeola has been their failure to deliver the original SDR transaxles to Factory Five customers on schedule or even a little behind schedule. My understanding is the original orders have been fulfilled. I inquired of Factory Five what kind of deposit and lead time they required for future SDR orders. Factory Five indicated they were not taking any SDR orders at this time.

The Mendeola website is running a banner ad indicating the SDR is coming soon. The online catalog that opens for the banner ad lists the SDR5. Page 7 has the following pricing:

• SDR5 Transaxle - $10,950
• GTM Mount - $475
• Master Shift Setup - $2400
• Gear Dash Indicator - $295           

There are probably some other things I need, so the entire transmission and shifting setup could cost somewhere north of $16,000. This is $4000 to $5000 over budget. Not good news on the money front, but great news on the durability front for a transaxle that is brand new and can handle the HP and torque coming off a LS 376/525 EFI engine.

GTM Radiator

I got around to unpacking the radiator for the GTM. This is a stock OEM replacement radiator designed for C5 Corvette.

I went with a stock radiator for the following reasons:

1. My experience with the C5 under 100 degree temperatures in traffic idle situations. This the same set up as what will be installed into the GTM. Engine cooling runs up to around 230 degrees, then the fans kick in and she goes back to 215.
2. Fitment issues with the current GTM chassis. Alternative radiators (e.g. DeWitts, BeCool) have a bigger footprint. I am planning enough deviations from the standard spec on the car that I really do not want to deal with an additional issue. If/When I get into trouble, I can always go back to look at the Corvette and see how everything is put together.
3. I do not plan to race the car, so I see little upside benefit for a radiator costing $400 - $600 more and requiring additional work to get it installed.
4. I have other places where i want to spend money (some glamour / some performance / some just plain fun).

The Budget

The base, no frills GTM is advertised as $20,000 plus a donor C5. This is a true statement as far as it goes. However, very few of the builders are doing the base GTM. Most are opting for something newer than the LS1 engine found in the basic C5. The performance of the LS1 (e.g. 345 to 350 HP, depending on the year of the C5) can be substantially improved to the 420 HP with simple things like a larger intake manifold, cold air intake, iridium plugs, better exhaust system.

This approach does produce a sporty, fun car to drive. The LS1 engine is no slouch, and mounted in a chassis weighing around 2400 pounds, it would be fast. Not 200 mph fast, but sneaky fast.

If I were just interested in going through the exercise of building a car, I might go this route. However, I'm interested in building a super car that has an astonishing performance envelope.

To my mind, this means new engine, new transmission, big wheels, big brakes, enhanced electronics and upgraded interior that leaves the fellow in the dust asking, "Who was dat guy?"

So there is an X factor not reflected in this budget. The X factor are those things that do not have to be part of the initial build, but can be added over time.

Built to order GTMs start around $110,000 and go up from there. Yes, there are GTM builders, and they have found a market. Dave Smith (Factory Five's President) says that he has people asking to buy completed GTMs. His answer is you can't buy it, you can only build it. A builder that produced between 5 to 10 of these per year would have a pretty decent income.

There is another benefit. Factory Five kit cars seem to hold their value. I think this is because they aren't just an exotic body shape glued to a rusting VW or Fiero chassis. These are real cars that people want.

Item	Estimate
brakes	2000
donor	11000
wheels	3200
Kit	25000
engine	9500
harness	1500
transmission	9000
Paint	3000
electronics suite	4000
Total	68200

For round numbers, let's peg it at $70k spread over three years, with the middle year incurring the greatest expenditure.

I realize budgets aren't much fun to figure out, but they are a necessary part of the pre-build. The GTM project is not simply an engineering and mechanical puzzle, there is a financial component that needs to be faced up front. If you don't have the financial wherewithal to finish the job, then don't start.

The budget doesn't reflect tool rental, shop supplies or incidentals. I plan to keep shipping costs separate. Items like powder coating parts, ceramic coating, windshield install that need to be sent out will be covered under miscellaneous expenses. My goal is to provide anyone following this build journal a good idea of where and when costs are incurred.

First Things First: Kit Detail

Once I decided to build the GTM (not something I came to overnight), then I had to figure out how to cash flow the project. If I had the ready cash to purchase all the components needed for the build, then I have the ready cash to buy the Ferrari and handle the maintenance. Since I concluded I didn't have those kind of resources, I needed to come up with a preliminary budget. I want my GTM to be unique (or as close to unique as possible). Let's be honest here, I want the final result of the build to be a rumbling, roaring beast capable of 200+ mph speeds and exceptional handling (the big grin kind of car).

The kit is the single most expensive component for the build, with engine and transmission coming in second and third respectively. Over the next couple of posts, I am going to detail the process of coming up with a budget and a purchasing order for the build. As it turns out, the kit is not the first thing I plan to purchase. However, we need to start with the kit (and options), due to the dependencies generated by the kit's composition.

Factory Five has an on line order form that details the base kit plus options. At this point, I am undecided about the carbon fiber splitter and rocker panels. I do not want a racing wing and I don't know if the donor will have a telescoping steering wheel. Since the Big Yellow Toy has one, I am inclined to get one here as well. The cost break down for the options I do want are as follows:

1. Base Kit - $19,990
2. A/C Unit - $1,350   (There is no way I am not going to have A/C as this will be a summer car)
3. 18 inch Wheels - $1,299 (This is a no brainer. I can't put the big brakes on the car without the big wheels)
4. Fender Louver - $199
5. Roof Scoop - $199
6. Logo Floor Mats - $115
7. Car Cover - $275
8. Cold Air Intake - $399  (Power! Power! Power!) 

This totals out to $23,826 plus shipping and handling. Let's just say it is $25,000 for round numbers. Granted I don't need all of these things right away, however, I want to optimize shipping costs by purchasing the major components in one shot.