Transaxle Particulars

[LCD Gauges]

I’d like to grab a transaxle within the next week. The problem is, I’m having difficulty getting specific details…but not for lack of trying. I’ve tried several searches on this forum, and the “other” which return hundreds of pages. Even when trying to narrow results using different keywords, and combos of keywords the list are too long, and the threads I’ve read thus far don’t address my questions.

So far I’m getting the feeling that a large majority of the GTM drivers would rather have a 6 spd. transmission. That may not be the perfect solution for my setup, but I’m keeping this in mind as resale value, and/or highway cruising (exhaust drone, RPM). TX coolers are also highly recommended, and I’ll be installing one for sure.
Another concern is that certain pieces don’t fit as I would expect. For example, the Mendeola cannot accept the stock size flywheel when mating to an LS7 engine. According to one source, it requires an LS6 flywheel. These are the sorts of particulars I need to learn before making a final decision, and grabbing the parts.

So I’m calling on the G50, and Mendeola owners for some help with my comparison!

I’m using an LQ9 engine with about 400-450 estimated crank HP @ 5600 RPM. The car will weigh as per usual build (I don’t plan on adding any additional components). Tire diameter will be ~ 27.74 inches.

What parts will I need, or what parts do you recommend based on your build/driving experience? Here's what I've learned at the moment:

_______________________________________G50/ x_________________Mendeola_____

Bell Housing……………………………………………………__Factory Porsche.............__Factory GM_
Flywheel (Thickness, # of teeth)………………… ____?_____.......................__LS6, or Equiv.__
TOB/Pilot Bearing……………………………………………____?____................. ..__Factory GM, or Equiv.
Clutch …………………………………………………………….___?_____................. ..__Exedy, McLeod, etc.__
Slave Cylinder / Release Mechanism…….._FF Supplied / ?.................__Factory GM, or Equiv._
Shift link type (cable / rod)………………… Cable Reccomended_..........___FF Supplied_________
Starter (size, torque)………………………………__High TQ. Mini Starter__.._ Factory GM_____________
Starter Mounting/Shimming…………………….__Mounted to Tx._............._Factory location________
Axle adapters…………………………………………._____?____............... .............____?_________
Speed Sensor / Reluctor Wheel………………__FFR Supplied...........................__?__________
Adapter Plate.....................................FFR Supplied............................ N/A___________
Conversion items / details………………………____?_____........................ ....__N/A___________
Other?..._________________........................ ... _________............................_____________


Thanks for any leads, and info!

[crash]

_______________________________________G50/ x_________________Mendeola_____

Bell Housing……………………………………………………__Factory Porsche.............__Factory GM_
Flywheel (Thickness, # of teeth)………………… ____?_____.......................__LS6, or Equiv.__
TOB/Pilot Bearing……………………………………………____?____................. ..__Factory GM, or Equiv.
Clutch …………………………………………………………….___?_____................. ..__Exedy, McLeod, etc.__
Slave Cylinder / Release Mechanism…….._FF Supplied / ?.................__Mendeola Supplied
Shift link type (cable / rod)………………… Cable Reccomended_..........___FF/Mendeola Supplied_________
Starter (size, torque)………………………………__High TQ. Mini Starter__.._ Factory GM_____________
Starter Mounting/Shimming…………………….__Mounted to Tx._............._Factory location________
Axle adapters………………………………………….___930 CVs_............................____930 CVs_________
Speed Sensor / Reluctor Wheel………………__FFR Supplied...........................__Mendeola Supplied________
Adapter Plate.....................................FFR Supplied............................ N/A___________
Conversion items / details………………………____?_____........................ ....__N/A___________
Other?..._________________........................ .............................____Built In Fluid Pump Option_________


Thanks for any leads, and info!

Call Ian at Mendeola for more info...619-710-8800 ex110

[Kempo]

_______________________________________G50/ x_________________Mendeola_____

Bell Housing……………………………………………………__Factory Porsche.............__Factory GM_
Flywheel (Thickness, # of teeth)………………… ____?_____.......................__LS6, or Equiv.__
TOB/Pilot Bearing……………………………………………____?____................. ..__Factory GM, or Equiv.
Clutch …………………………………………………………….___?_____............ ..... ..__Exedy, McLeod, etc.__
Slave Cylinder / Release Mechanism…….._FF Supplied / ?.................__Factory GM, or Equiv._ Supplied with the transaxle. Not a GM unit
Shift link type (cable / rod)………………… Cable Reccomended_..........___FF Supplied_________
Starter (size, torque)………………………………__High TQ. Mini Starter__.._ Factory GM_____________The factory GM won't work. you need the IMI-140
Starter Mounting/Shimming…………………….__Mounted to Tx._............._Factory location________
Axle adapters…………………………………………._____?____............... .............____?_________The Porsche 930 inner CV bolt directly to the flanges on the Mendeola
Speed Sensor / Reluctor Wheel………………__FFR Supplied...........................__?__________C5 Corvette speed sensor/the reluctor wheel is already integrated to the drivers side CV flange on the trans axle
Adapter Plate.....................................FFR Supplied............................ N/A___________
Conversion items / details………………………____?_____........................ ....__N/A___________
Other?..._________________........................ ... _________............................_____________

[crash]

IIRC, the last time I was down at Mendeola, Ian told me that they are going to be making a bell housing that will allow the use of the STOCK starter. I thought the issue was the fitment with the Kooks headers, but maybe there was something with the bell housing also? Not 100% sure on that, but it probably will fit if the stock cast iron manifolds are used.

[LCD Gauges]

Thanks guys. The picture is becoming clearer. Ill update once I run through a few hundred more threads!

[crash]

BTW- I might add that while many of the items are included or are options with the Mendeola, the specific products are not neccessarily unique to Mendeola. In other words, you can find them through other suppliers so parts sourcing is not a one source type of situation. For instance the shifter can be found from a couple different sources, as can the slave cylinder, fluid pump, starter, flywheel, clutch, and CVs. So while you may find yourself not close to Mendeola if something should go wrong, you can source these parts from other companies and they are likely to be just as readily available, or more so, at a better price point in almost all cases, than you will find with the Porsche. Don't get me wrong, there are many parts that are proprietary to Mendeola in the SDRs, but I thought I would point out that there are also many items that can be sourced elsewhere should the need, in a crisis, arise. :) Although with UPS, Fed Ex, USPS, etc, Mendeola is only a day or so away these days! :)

[LCD Gauges]

Cool info Crash, I'll keep that in mind.

As for the G50 research, the best answer I've found is that the clutch, starter, etc. will be Porsche brand, and the flywheel will be GM. The starter needs a gear to match the flywheel.

Anybody have recommendations on clutch kits for G50? Once I get a few more pieces of this puzzle figured out, I'll be making the decision. I'll update the chart once I get the details.

[VD2021]

Cool info Crash, I'll keep that in mind.

As for the G50 research, the best answer I've found is that the clutch, starter, etc. will be Porsche brand, and the flywheel will be GM. The starter needs a gear to match the flywheel.

Anybody have recommendations on clutch kits for G50? Once I get a few more pieces of this puzzle figured out, I'll be making the decision. I'll update the chart once I get the details.

I don't know if you can fit a GM flywheel into the bell housing area of a G50:D.

For all of your G50 questions and/or items I would recommend contacting Stan (http://www.gboxweb.com/) and/or Roger (http://www.californiamotorsports.net/Kit%20car.htm).

[narkosys]

I really like this discussion. It is helping me a lot in my research. So far my favourite combination is a Turnkey-Mendeola drivetrain package as I am going donor pallet (so far, this may change when I get closer to purchasing the kit). Hopefully they will offer a 6 speed tranny by then. The G50 6 speed is still enticing though.

P

[crash]

The flywheel for the G50 will be a semi custom part, probably sourced from Kennedy Engineered Products. It is a Porsche flywheel with a GM crank bolt pattern fitted to it. This allows the Porsche clutch to be mounted onto the LS engine. As you can guess, this part is a bit more expensive than an off the shelf GM flywheel. Not a deal breaker for sure, but another piece of the puzzle. :)

[LCD Gauges]

Here's a good link on the S5

http://www.californiaperformance.com/s5_sequential.htm

I'll be contacting Ian this afternoon, and uploading a much more detailed and accurate spreadsheet.

[LCD Gauges]

IIRC, the last time I was down at Mendeola, Ian told me that they are going to be making a bell housing that will allow the use of the STOCK starter. I thought the issue was the fitment with the Kooks headers, but maybe there was something with the bell housing also? Not 100% sure on that, but it probably will fit if the stock cast iron manifolds are used.

You are correct, I spoke with Ian about this. After Mendeola completes the current shipping list, they will be fitting the future transmissions with a bellhousing that resembles the GM layout
for starter location.

Sorry that I haven't uploaded the spreadsheet yet, I've got some excellent details with prices (approximate) for those wanting to choose their driveline components.

[LCD Gauges]

Here is a quick, and dirty comparison chart between the G96, SDR-5, and G50/50. You will note that some price figures are missing, and this is
because I don't have a reliable figure to enter. These numbers are rounded up, or down to the nearest hundred. They are ball-park figures.

Power handling is not given because there are several factors which will determine how the transmission will handle the torque. You could have
800 HP, slip the clutch, never power shift, and have a long lasting driveline. You might have 300 lbs.*ft. of torque at 2000 RPM, or 300 lbs.*ft.
at 6000 RPM.

Most of what I have read, researched from the experts themselves, and learned in my years of automotive tells me that common sense for the
mild-to-somewhat wild street/strip engine will be fine for either of the transaxles listed on the chart.

Also noteworthy:
- The G96 requires flanges to be welded to the frame for transaxle mounting. The Vette axles need to be modified to work (not sure what's involved yet)
- The G50/50 is a rod link shift mechanism. Apparently, this is not the best for accurate, consistent shifts. An adapter kit is required to change over to cable shift.

If anyone has additional, well sourced info on the question marks, or can point out any errors, don't hesitate to list them. I will update the spreadsheet as
more data comes along.

Sorry for the wait!10620

[crash]

Every one of these options will need the inner CV joints. www.myraceshop.com offers the complete set for $255.28. http://www.myraceshop.com/930_CV_Kit.html Much less than the $400 you have listed. Also, you have 935 CVs listed and AFAIK these are custom parts as far as the flanges, and you should know that the CV joints in that size run about $300 A PIECE. There really is no reason to run these on any street driven vehicle. The 930s can be upgraded for a total 2 CV kit cost of $455.28. This is a 300M star upgrade and makes the 930 capable of handling 1000 HP for street use. Have 1000 HP and put sticky tires on it? Yeah, you'll need the 935s. Go to insane power levels, like 2000+ and the CVs go up in size and cost substantially. So much in size that you can no longer use the Vette upright. Oh yeah, and the CVs cost ~$600 A PIECE!

[LCD Gauges]

That's great input, I'll update the spreadsheet this week. I may also include some theoretical performance figures for *my* engine / tire combo when using either of the listed transmissions, and final ratios.

[VD2021]

I’d like to grab a transaxle within the next week.

Tino,

Have you made your choice yet?

[LCD Gauges]

Not quite yet, I'm still waiting for one formal quote.

The bigger issue is that I was wayyyyyyyyyy off when estimating the price of the transaxle when initially researching the GTM kit costs. I didn't realize all of the extras / options would turn into essentials.

IE: Limited slip upgrade (though it would have LSD). The cable shift as opposed to rod link. Fluid cooling pump, and accessories.

Therefore, I'll need to wash a few more dishes in order to afford everything. I'm still hoping to place the order by month end.

[LCD Gauges]

Just days away from grabbing the transaxle, and I've been plugging away to compare my options. This chart is based on my Camaro's dyno
graph, but it gives some vital information when putting the gearing, and final gearing side-by-side.

I'll be inputting my LQ9 engine specs into a CFD program to get an estimate of torque over RPM for the components used in my build. The two
charts below will help me predict average power, "or area under the curve" when using either dyno graph.

At first glance, it appears the G96 will accelerate out the hole faster (if the traction holds), but the 1-2 shift ratios are not as well matched as
the Mendeola. I thnk the G96 was meant for AWD vehicles that don't have such issues with traction.

The Mendeola keeps the engine (as per spreadsheet) in the power range slightly better due to the transmission ratios. The final drive helps
get the force back to the wheels. It also means the cruising speed will be a touch higher (or about 200 RPM lower highway cruise RPM at static speed).

.

It would be tough to say which transmission would out accelerate in a straight line, but I would *think* the G96 might be better in a 1/4 mile setting,
where the Mendeola is better on a track course where short straight bursts, and accelerating out of curves would be helpful.

The G96 was figured with a 3.44 final, and the SDR5 was figured using a 3.55 ratio.

1075310754

[crash]

Just to throw another wrench into this discussion, I talked with Mike Mendeola about upcoming transaxles, and he gave me an available gear chart for a new model transaxle they are working on. Here's the available ratios...

1st on layshaft
3.09
2.92
2.77
2.67
2.57
2.46
2.25
2.21

2nd Gear
2.35
2.30
2.25
2.21
2.17
2.12
2.07
2.00
1.97
1.93
1.87
1.82
1.77
1.72

3rd, 4th, 5th Gear
1.87
1.82
1.77
1.72
1.68
1.62
1.57
1.52
1.47
1.42
1.37
1.32
1.26
1.22
1.17
1.14
1.10
1.07
1.02
.96
.92
.87
.82
.77
.72
.67
.62
.55
.50

Final Drive 4:11, 3:55, 3:08

Mike also said there will be more than a dozen different styles of differentials available for this new box. :)

Many of you probably saw what I posted in the other thread, but I thought I would post it here as well just for future referrence by potential builders.

[LCD Gauges]

Oh... the luxury of selecting gears for each individual engine/track.

Maybe I'll dream a little and calculate what I'd pick having the race trans. in my car. :cool:

[LCD Gauges]

My decision, and thought process (love it, or leave it):

The 6 speed, G96.

After crunching numbers, playing with calculators, and simulators it's a very fine line between both transaxles. Using some data from my accelerometer (shift times, g, RPM/s),
estimated power curves, and all that funky stuff both transmissions are within a tenth of each other. As suspected the G96 *should* get off the line faster, and the Mendeola
accelerates faster from a roll (2nd to 3rd gear).

While playing with the numbers I saw that 2nd gear on the G96 is close to first gear on the Mendeola. Starting out in 2nd gear turns the tables a bit, however the G96 may
actually be faster still going into the 4th gear when the Mendeola is going into its 4th gear (1.22 vs. 0.89). With the ring/pinion ratios being only 0.11 apart, it makes for an
interesting scenario.

Aside from all the speculation, the G96 also felt like a better choice due to the 'decent' cruising gear (slight difference), as well as the lead time. Mendeola is buidling some
units for the initial order, but will be online in about three months. The timeline is not really an issue as my car is nowhere near ready. In the end, either transmission is gold
for the GTM. Anyone building a mild-to wild LS engine will be happy with the ratios offered.

The G50/50 is also a closely matched gear setup considering the 3.44 ring/pinion ratio, but based on my research for pricing/options/etc. the Mendeola would be a better solution
for *myself*, and that is why I stopped comparing those units early on.

The graph is a side-by-side comparison of the gearing against the power curve. 1st gear is from idle to 7000 RPM, and the first left edge will be the 2nd gear RPM. G96 on
the left, and SDR5 on the right.
10775

[LCD Gauges]

Some more data to update this thread. Eventually, I'll consolidate the comparison information into the initial post with new spreadsheets.


G96/00 Gearing

1st gear: 3.82

2nd gear: 2.20

3rd gear: 1.52

4th gear: 1.22

5th gear: 1.02

6th gear: 0.84

Ring and pinion: 3.44


G96 2nd gear start w/3.44:1 vs Mendeola 1st gear start w/3.55:1
G96_Mendeola

2.20_2.21

1.52_1.50

1.22_1.14

1.02_0.89

0.84_0.70

To make a case for my decision I used several tools, and crunched some long math to get an idea of which transaxle would be best. Without having an engine dyno handy,
I used a software program, as well as some real world builds to estimate the power curves. In addition to that, I used my old dyno charts, and track slips from the Camaro
to guage how closely the software was able to predict 1/4 mile times, and engine power.

Here are the first sets of screen shots to show my work. I'll get the G96 vs. SDR-5 photos uploaded within the next couple of days.

Remember, you are looking at a Camaro SS with a T-56 transmission weighing 3600 lbs., NOT the GTM with transaxles discussed above.

Time slips after installing new clutch. Got the 60' down to a respectable point. Software predicts 12.2 second quarter vs. actual 12.56.
The MPH are pretty much exact.
1081210816

TQ/HP graph values used for software input
10813
g graph through the gears from the G-tech Pro Accelerometer (calibrated to track beams within a tenth/sec). 1st, and 2nd gear g values are pretty much
bang-on between accelerometer, and data prediction.
1081410817
Time to speed from the G-tech Pro Accelerometer. 0-60 MPH times are close between G-tech, and software.
1081510816

More to come (if you like this sort of thing...).

[LCD Gauges]

Here are the last simulated scenarios. Believe me when I say that both of these transmissions are dead nuts equal in performance (based on manual calcs, and simulation).
Also note, I did not play with the shift points yet, therefore they are not optimized. There is only a difference of a few hundred RPM, and the time spent in that window is
equivalent to dozens of milliseconds at wide open throttle. Therefore, the acceleration is pretty much equal given the same motor powering the car.

I'll also conclude that the G96 first gear is essentially a throw-away gear. YOu will not achieve much launching the GTM from a dead stop in first gear unless you like smoking
the tires, and hitting your rev limiter quickly. My previous car had a 3.42 final, with a 2.66 first gear ratio. It weighed 3600 pounds and blew the tires as if driving on ice.
The G96 first gear will be much worse, with a lighter frame, and equally powered. You will be forced to start in 2nd gear when acclerating hard from a dead stop (using street tires).

Having stated the obvious, the Mendeola would be an easy choice as the gear ratios are essentially the same, and the 5th gear actually gets you a better highway cruise RPM
even with a 3.55 final ratio.

I'm not implying anything with the following charts other than, we are splitting hairs when debating between the two. Enjoy the pictures, and I hope anyone starting the research
from point zero (like myself), will save some headache, and uncertaintly when selecting their transaxle.

Lastly, the only true test is having both transmissions available to swap into your car for A-B comparison.


G96/00, 2nd gear start
1082910830

G96/00, 1st gear start
1083110832

Mendeola SDR-5
1083310834

[crash]

One small point I would like to make.

The Mendeola is comprised of ALL NEW parts. Where as the Porsche boxes are going to be used boxes. Also, the internals of the Mendeola are MUCH LARGER than those of the Porsche. True enough that metallurgy is key in these types of components, and frankly I don't have enough expertise to say one way or the other which company has better metellurgy, but if the materials are equal, then, IMHO, the advantage would be to the Mendeola since it is substantially larger in main shafts and gears. Probably just a bit heavier, but there is a reason for that! :)

[narkosys]

but, for now, the Mendeola only comes in a 5 speed. For someone (me) who will be using his GTM as a street car and daily driver with lots of highway miles as I live in the mountains, a 6 speed gearbox is more of an advantage. If Mendeola made a 6 gear box I would edge more towards that as like you said they are new parts and are beefier.

P

[Kempo]

One small point I would like to make.

The Mendeola is comprised of ALL NEW parts. Where as the Porsche boxes are going to be used boxes.

I agree with Crash. This is basically the main reason why I chose the Mendeola. Being able to use the GM clutch and the IMI starter is a plus too as they are way less expensive than the Porsche units.

According to Tino's numbers the mendeola would yield better fuel economy driving at top gear.

[mendo]

but, for now, the Mendeola only comes in a 5 speed. For someone (me) who will be using his GTM as a street car and daily driver with lots of highway miles as I live in the mountains, a 6 speed gearbox is more of an advantage. If Mendeola made a 6 gear box I would edge more towards that as like you said they are new parts and are beefier.

P

the way I looked at it the 1st gear on the porche box is nice for driving around in the parking lot, but leaving in 2nd with the torque that the GTM has makes more sense and I can get to almost 70 in 2nd depending on which gears I end up with.
so the 5 speed isn't that bad.

[narkosys]

to the car gurus: would it be possible to change out the gears in the G96 to something more usable? looking at the charts I would say start with a 2.20 or 2.21 for first and work your way up? I like the Mendeola (especially if I go with the Turnkey/Mendeola drivetrain package they offer) but I would like to have that 6th gear to play with in the mountains and on the highways.

P

[LCD Gauges]

I agree with Crash. This is basically the main reason why I chose the Mendeola. Being able to use the GM clutch and the IMI starter is a plus too as they are way less expensive than the Porsche units.

According to Tino's numbers the mendeola would yield better fuel economy driving at top gear.

The G96 allows the use of the stock GM starter, but clutch options are fewer from what I"ve seen.

The Mendeola does indeed yield better cruise RPM, and fuel economy. It will also have the capability of achieving a higher
speed if the engine, and aerodynamics of the GTM will allow such a speed.

The G96 is essentially a 5 speed gear box with a really wild, and somewhat difficult first gear thrown in...

In my opinion, the G96 could have used more attention in the first five gears with a lower ratio overdrive, or perhaps two overdrive
gears like the Corvette transaxle (or T-56 for that fact).

I'm pretty sure you can pay a fee to have the G96 gears swapped out to your custom needs. I'm not certain of the price.

Ring gear diameters are 9" for the Porsche boxes, and 10" for the Mendeola.

[Joe Mush]

I have the Mendeola five speed and at 75 mph my LS1 tecs about 2200 rpm.

[LCD Gauges]

to the car gurus: would it be possible to change out the gears in the G96 to something more usable? looking at the charts I would say start with a 2.20 or 2.21 for first and work your way up? I like the Mendeola (especially if I go with the Turnkey/Mendeola drivetrain package they offer) but I would like to have that 6th gear to play with in the mountains and on the highways.

P


If you're going that route, be prepared to pay for the gears, as well as the labour to install them. It would be a very expensive alternative
to perhaps changing the final ratio to something numerically lower. `I`ve had a 6 speed transmission for years. It was a toss-up
between using 5th, or 6th for highway driving. If fifth gear dropped out, I would be hard pressed to have it fixed if you know what I mean.

The trouble is, the G96 first gear is very oddly matched to the rest of the set. Even if you tame down the ratios with a 3.2x (or lower)
final ratio, then you're dealing with a less than optimal step between first and second gear shifts.

I`m not really sure why the additional gear is so important. I have not found a use for it yet. Overcoming the temptation to purchase
a 6 speed over a 5 speed is likely due to peer pressure, or Internet bench-racing. Kinda like the way you felt when you learned that
Santa Claus wasn`t real. :D


If you're looking at the G96 as an option, don't buy it because it has "6 gears". BUy it because it has intergrated cable shift over the
5 speeed Porsche boxes. Buy it because it's geared more aggressively, and has a better overdrive ratio (except for the G50/50).
Drag racers wont need more than four gears to clear 1320 feet.

When putting the Mendeola side, by side with the G96 you could argue the ratios are slightly better for accelerating. You might also
use availabilty as criteria (this will be a non issue in about three months). Price: Rebuilt vs. Brand new...a couple thousand at most. The only other factor that might sway the Canadian builders is that Porsche transmission dealers, and shops are closer for service.

Those were my reasons for choosing the G96. I don`t feel as though I`ve got an upper hand whatsoever. It`s just something that
worked best for me at this time.

FYI: At 75 MPH, the G96 revs to 2615 RPM with a 27.75 inch tire for comparison.