Lunchietey Member 84 Member For: 13y 8m 20d Gender: Male Location: WA Posted 04/04/18 10:59 PM Share Posted 04/04/18 10:59 PM Ok so common knowledge is the ba/bf wagon is speed limited to 180 due to the long single piece tailshaft. They have a factory 3.23 diff. Now I have been considering an upgrade since the turbo went on to a 3.7 LSD to help with the looong first gear in the BTR. This means faster tailshaft RPM at the same speed(14% give or take) meaning max speed (based on tailshaft RPM) is now 157... That speed might be hit on a 1/4 mile with that diff after all of my mods are done, and probably easy to hit overtaking a long truck in a 110 zone. Is it a concern? Link to comment Share on other sites More sharing options...
k31th less WHY; more WOT Site Developer 28,300 Member For: 16y 13d Gender: Male Location: Melbourne Posted 04/04/18 11:03 PM Share Posted 04/04/18 11:03 PM not if you remove the speed limiter in the tune. Link to comment Share on other sites More sharing options...
Lunchietey Member 84 Member For: 13y 8m 20d Gender: Male Location: WA Posted 04/04/18 11:56 PM Author Share Posted 04/04/18 11:56 PM I'm worried about the higher rotation of the driveshaft (which is the point of the limiter). The wagon will still do 180 as diff ratio doesn't determine the speed the ecu sees but the driveshaft will need to spin 14% faster to do it. Will vibration/failure be an issue? Did ford leave a good safety margin? I can't see myself doing 180 but 160 is very easy to do on a strip or overtaking in a 110 zone which will exceed the driveshaft rpm that ford had limited. 180 will be more like 205 on the old diff Link to comment Share on other sites More sharing options...
k31th less WHY; more WOT Site Developer 28,300 Member For: 16y 13d Gender: Male Location: Melbourne Posted 05/04/18 12:01 AM Share Posted 05/04/18 12:01 AM who knows what margin they left... you'd only be guessing. Link to comment Share on other sites More sharing options...
Ralph Wiggum Moar Powar Babeh Lifetime Members 19,323 Member For: 18y 7m Gender: Male Location: Perth Posted 05/04/18 03:49 AM Share Posted 05/04/18 03:49 AM Tune will adjusting as shifts points are based on output shaft (driveshaft) rpm which will be higher in relation to road speed Link to comment Share on other sites More sharing options...
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