Saturday, December 6, 2014

Fitting the Mendeola Transaxle

Here's an interesting idea I've pursued lately.  I'm looking into putting a Mendeola SDR5 into the Pantera.  It's a transaxle developed specifically for the kit car world, and it is similar in size to the ZF but slightly longer.  It weighs 14 lbs more than the ZF in full dress at 168 lbs with bellhousing, but that includes slave cylinder, etc. In all, it might be 10 lbs heavier.

The benefits of such a swap are as follows:

1.  It's a cheaper transaxle when comparing a new RBT 5-speed, with similar power handling.  Both the ZF and Mendeola will handle 500 ft-lbs of torque.
2.  The SDR is much cheaper to repair.  An average rebuild is $650 labor plus parts.  A gear set might be $400 (versus $1275 for the ZF) and synchro rings cost $30 (versus $300 for the ZF).  You can replace any bearing or seal without going to Mendeola as these parts are off-the-shelf.  No more $550 pinion shaft support bearing as in the ZF!
3.  The SDR will shift faster.  Slow, deliberate shifting keeps the ZF in good shape, but the Mendeola won't be as slow-shifting.
4.  Racing applications requiring a transmission cooler are really easy since the transmission comes set up to accept an external cooler and pump.
5.  The shift pattern is a standard H-pattern with first being forward and to the left, second straight back from first, and reverse to the side of 5th gear.

The downsides are as follows:

1.  It will probably cost more than a rebuild for a ZF.  The SDR will require CV axles, along with a different clutch and need to run an electronic speedometer.
2.  It's not stock.
3.  It will require a cable shifter.
4.  Gear ratios aren't very different from the Pantera.  More gear ratios are possible though.

I see the swap being popular with people who regularly race their Panteras and want to have a transaxle that is just as robust but cheaper to repair and easily set up for racing.  Ian w/ Mendeola sent me an empty case to experiment with, including parts of the shift linkage and a bellhousing.

The tranny fits well, but needs a new bellhousing since the current one runs the transaxle in the standard position.  The Pantera will run the transaxle in the inverted position.  There are no major internal changes necessary, or so I'm told.  I'm working with Mendeola for an inverted bellhousing.

The shift mechanism works but I had to move it back from where it was.  The tranny will have to run a cable shifter.  The pad intended for the tranny mount is clearly visible.

Clearance to the sway bar is close.

Here's the end without the end case on.

The end case is too long at the input shaft oil pump housing. 

Another view.

Here's how the case and supports line up.

I had to machine off the fins to fit the transaxle over the lower frame crossmember.  Looks like I need to clearance it more for the sway bar.

Another view of the machining for clearance.

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