dcairns Posted April 23, 2003 Report Share Posted April 23, 2003 Went to schedule a dyno test, and lo and behold, my truck is too long for the AWD dyno!!!! Now how on earth am I supposed to be scientific about measuring the performance increase with out a baseline test? This leaves me with just comparing before and after 1/4 mile times. I found another AWD dyno, but it is not available to the public, being a captive R&D dyno for GIAC. I am running out of time before the supercharger gets installed! Do any of you GM techs lurking out there know how the AWD system responds to being dyno tested with the front wheels off the ground? It sounds rather kludgy and dangerous, but one dyno shop offered to do it that way. Would you get a reading of all the power or just the 60% that is directed to the rear wheels? Link to comment Share on other sites More sharing options...
SSilverado60 Posted April 23, 2003 Report Share Posted April 23, 2003 Besides being dangerous, your numbers will not be accurate Link to comment Share on other sites More sharing options...
MN C5 Posted April 23, 2003 Report Share Posted April 23, 2003 Went to schedule a dyno test, and lo and behold, my truck is too long for the AWD dyno!!!! Now how on earth am I supposed to be scientific about measuring the performance increase with out a baseline test? This leaves me with just comparing before and after 1/4 mile times. I found another AWD dyno, but it is not available to the public, being a captive R&D dyno for GIAC. I am running out of time before the supercharger gets installed! Do any of you GM techs lurking out there know how the AWD system responds to being dyno tested with the front wheels off the ground? It sounds rather kludgy and dangerous, but one dyno shop offered to do it that way. Would you get a reading of all the power or just the 60% that is directed to the rear wheels? How about removing the front driveshaft? Thats what I'm planning on doing... ;) Link to comment Share on other sites More sharing options...
dcairns Posted April 23, 2003 Author Report Share Posted April 23, 2003 How about removing the front driveshaft? Thats what I'm planning on doing... ;) I have heard of the SyTy folks doing that, but will I still get all the power to the rear? I am not sure how the computer, traction control, etc all work when the front wheels are unloaded. Link to comment Share on other sites More sharing options...
BigTex Posted April 27, 2003 Report Share Posted April 27, 2003 It will set off an SES light if you unhook the front driveshaft. I dont know if it will actually put the truck into "slug" mode or if its just a warning. I guess it wouldn't hurt to try. Heck, there are only 4 small bolts holding the front driveshaft in place. Remove the bolts from the front yoke and the rear will pull directly out of the transfer case. You'll probably have to pull down the drivers side exhaust pipe to get at it. Drive it around and see how it feels. If it sets a code, you cna just reset the PCM to clear it, then put the driveshaft back on. Link to comment Share on other sites More sharing options...
SSilverado60 Posted April 28, 2003 Report Share Posted April 28, 2003 It will set off an SES light if you unhook the front driveshaft. I dont know if it will actually put the truck into "slug" mode or if its just a warning. I guess it wouldn't hurt to try. Heck, there are only 4 small bolts holding the front driveshaft in place. Remove the bolts from the front yoke and the rear will pull directly out of the transfer case. You'll probably have to pull down the drivers side exhaust pipe to get at it. Drive it around and see how it feels. If it sets a code, you cna just reset the PCM to clear it, then put the driveshaft back on. If it has a slip yoke then there is no possible way that will work. Because if that is done, then all the fluid will come out of the transfer case. I'm pretty sure that it doesnt have a slip yoke in the front though Link to comment Share on other sites More sharing options...
FlyinTurbo Posted June 22, 2003 Report Share Posted June 22, 2003 Has anyone come up with a reasonable solution to dynoing the truck in '2wd' mode? Can we unhook the front drive line? The first thing I plan on doing when I get my truck is to go dyno it... which is convenient for me since I have a dyno. Link to comment Share on other sites More sharing options...
SSilverado60 Posted June 22, 2003 Report Share Posted June 22, 2003 I think you could damage the t-case by doing this because the differential in the t-case will be doing a lot of work in order to try and transfer the power to the rear. You will either brake something or have a very unnacurate dyno. Link to comment Share on other sites More sharing options...
GnatGoSplat Posted July 1, 2003 Report Share Posted July 1, 2003 You WILL damage something if you unhook the front driveline. You will cook the viscous coupler. With the front driveline unhooked, the viscous fluid will heat up and direct up to 100% torque to the wheels with traction (the rear wheels). However, the whole time the viscous fluid will be getting hotter and hotter. Sending 100% torque to either axle for too long of a time will cause the viscous fluid to overheat and burn out your t-case. This is explained in the service manual! Link to comment Share on other sites More sharing options...
MN C5 Posted July 2, 2003 Report Share Posted July 2, 2003 You WILL damage something if you unhook the front driveline.You will cook the viscous coupler. With the front driveline unhooked, the viscous fluid will heat up and direct up to 100% torque to the wheels with traction (the rear wheels). However, the whole time the viscous fluid will be getting hotter and hotter. Sending 100% torque to either axle for too long of a time will cause the viscous fluid to overheat and burn out your t-case. This is explained in the service manual! I was going that route too... But the new parts alone are about 1k. Hardly seems worth it for a dyno pull... Link to comment Share on other sites More sharing options...
SinisterSS Posted July 2, 2003 Report Share Posted July 2, 2003 Could always throw in an Auto-trac transfer case from a regular K1500. Swapping t-cases isn't too big a deal if you've got the t-case and a lift. ;) Link to comment Share on other sites More sharing options...
MN C5 Posted July 2, 2003 Report Share Posted July 2, 2003 Could always throw in an Auto-trac transfer case from a regular K1500. Swapping t-cases isn't too big a deal if you've got the t-case and a lift. ;) What part of MN are you located in SinisterSS Link to comment Share on other sites More sharing options...
SinisterSS Posted July 2, 2003 Report Share Posted July 2, 2003 Born and raised in West Central MN, lived in Moorhead, then the Cities for a while, then off to Sioux Falls and now currently transplanted in Illinois. I miss snow. Someday I'll be back! Link to comment Share on other sites More sharing options...
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