[jonkolo]

Originally Posted by rsnider

Re: WOT in a 4R70W. I thought I might try the Movaje Mile or the Texas mile with my auto Mach 1 but the speed shop said NO! They claimed the trans won't hold up under WOT. It thought I'd go straight to the source to I emailed a close friend who works at Roush but is retired from Ford Driveline. This is his response with names and numbers deleted. This only concerns WOT and not a 3-4 shift at WOT. Start at the bottom.


XXXXXXXXXX
Powertrain Engineering
Roush Industries
313-XXX-XXXX

Yep,
4R70 and 4R75 are mechanically identical but some components are of higher torque capacity.
Tell your friend to enjoy his drive
XX


On Tue, Aug 23, 2011 at 2:14 PM, XXXXXXXXX

XXX, thanks for the info. Assuming that 4R75=4R70 for this discussion. I'm just not as familiar with the badging.
Regards,

XXXXXXXX
Powertrain Engineering
Roush Industries
313-XXX-XXXX


Hi XXXXX,
the "never" drive at WOT in OD is a carryover concern from "WAY BACK WHEN" at the beginning when 4R75 was called AOD, and it had a lube issue for the gear set - that was corrected and doubly verified to be cured (multiple times) each time a new manager showed up and had heard the same concern. When XXXX XXXX was the manager, XXXX XXXXX was also concerned and they convinced themselves (and the rest of Ford ATEO) that there was indeed NO issue with running at high speed in 4th gear.
Just do NOT downshift to 2nd gear at high speed from 4th - this manuver will indeed cause major damage (this was a calibration error by a hard-headed calibrator who insisted on not allowing a downshift at high speed, despite the fact that the OWC would self destruct) - no I won't tell you who he was, but I'll bet you do know him.
BOTTOM LINE
It's OK to drive high speed in 4th.
Take care,
XXX


On Tue, Aug 23, 2011 at 12:38 PM, XXXXXXXXXXXX

Hi XXX, enjoy receiving the snippets. I forward them on to my brother in Winchester Tn. who has a plastics business that supplies into the industry.
How is your son doing?
A friend of mine has a 2003 Mustang with a 4.6L and subject trans. He had a performance shop do some work on the trans and put in a high rpm stall convertor. He was advised (with emphasis) to NEVER drive wide open in overdrive. The shop said the overdrive was meant for expressway cruising not max speed runs.
My friend would love to see what the top end of his car would be but fears going any faster than 3rd gear allows.
Is this an issue with the 4R that your aware of from your days in trans?
Thanks.
Regards,

I am very surprised that there was no mention about the harmonic driveshaft balancing issue at high speeds with the automatic mach/police interceptor. It is/was a very well known issue! I'm sure that you already know that all 03-04 auto Mach's/Police Interceptors are electronically limited to 127MPH. As far as I know, this prevents a WOT shift into OD, and it also protects the driveshaft from breaking due to excessive RPM's and causing major damage! I disabled my 127MPH speed limiter and drove my auto Mach up to 137MPH on GPS, but I could start to hear the resonance so I backed off!!! I'm really glad that I did because I recently had a driveshaft failure in my 2011 V6 at 135MPH! It really caused a lot of damage to the car and I would have cried if that had happened to my Mach! As far as the top speed of the auto, all I can say is that it gets to 130MPH in a heartbeat (3'rd gear), but once it shifts into OD there is not much acceleration because it's like running in 5'th gear with a manual mach. (They toped out at 151 in 4'th) I know mine hit 137, and there was probably more left, but exactly how much more I don't know because I started going up hill, heard the driveshaft, then I backed off. Go to youtube and search "Mustang V6 driveshaft failure", before you run your Mach faster then 130!