I have been watching with interest the B body 94-96 Impala SS guys swap the Ford Crown Victoria "P71" police cruiser drive shaft into their cars hoping I can use this shaft (shortened) in my 87 Monte LS engine swap. The shaft is a direct fit into B bodies with extended lower control arms. Apparently in the 1999 & 2000 model years, Ford installed 3.55 ratio rear ends in the cop cars and the critical drive shaft speed in pursuit situations was such that they installed a MMC (metal matrix composite) driveshaft designed to handle higher rotational speeds. The MMC driveshaft is made of an aluminum matrix reinforced with boron carbide, allowing the critical speed of the driveshaft to be raised by reducing inertia. http://en.wikipedia.org/wiki/Metal_matrix_composite
Quote from the Impala board: "MMC's elasticity allows the shaft to absorb more drive-line vibrations. The issue with shafts is that they create ultra high frequency vibrations at high rpms, which can cause them to self-destruct. MMC absorbs shaft twist and vibration much better. The MMC shaft's critical speed is 9093 rpm, and the normal P71 aluminum shaft is 7930 rpms."
While 3.5" Aluminium drive shafts are in all the late model Crown Vic P71 police cars these two years (1999 & 2000) are special. P71 denoting cop car is located in the 5,6 and 7th digit of the VIN. The MMC shafts have small Gold MMC lettering on one end so you can confirm you have the right one. Non MMC P71 shafts have the words “police” stenciled in black on them. The shafts are 55.5 inches long so I don’t know what other cars they will fit into?
I am installing a 8.5" Grand National rear end and 4L80E transmission in my LS swap so I purchased at Pic N Pull during a sale a MMC drive shaft for $26.38. 4 bolts at the rear of the shaft and the front yoke slides out of the transmission and you are done in 10 minutes. Make sure you have 12pt 3/8” metric sockets with you to fit the special bolts.
The 1999 - 2005 ford P71 shafts use 1330 u joints and my yoke is 1350 so I need a 1330 X 1350 conversion U joint in the front. In the rear the GN rear end uses a 3R or S44 U joint so I need a 1330 X S44/3R series conversion joint. Both joints can be found on eBay. The 1330 X S44/3R series U Joint is the same one the Impala guys are using which makes sense since those cars also have 8.5” rear ends. I have not yet had the driveshaft shortened and hopefully the MMC material does not create welding problems? If so I will get a regular Crown Vic P71 3.5” shaft as the critical speeds mentioned above for even the regular shaft are higher than I will ever go. Up here in Canada its $150 to shorten and balance a drive shaft at my local shop.
There is some suggestion on the Impala site that the 2006 and newer P71 cop cars use the larger/stronger 1350 U joints. Another option?
This is a shade tree way to get a 3.5" aluminium shaft for cheap. I think G Body stock steel shafts are only 2.75” and a Grand National stock Shaft is 3” but someone may correct me.
Does anyone know how much power these Ford shafts will take?
Heres the link on the Impala board for pictures of the shafts and further details. It’s a 15-16 page read.. One contributor provided a decoder (post # 86) for the Rear End Tag so that you can confirm you have a 1999-2000 MMC shaft. http://www.impalassforum.com/vBulletin/showthread.php?t=271635