M6 GTO Driveline Reliability
06-14-2016, 02:42 PM
#1
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M6 GTO Driveline Reliability I am in the process of building a rear end for my M6 GTO. Only issue is while doing research I have been seeing a lot of conflicting information about getting this rear end to hold 650 tq with an end goal of 750 tq. The car is my daily but I also like to take it to the track. I want to be able to throw some drag radials on it and run in the high 10s. My plan was to get a Tick Level 3 rebuild for my T56 and install a new clutch, Hinson driveshaft, DSS 1000HP axles and stubs, and TrueTrac or Kaaz diff. But now I am seeing a lot of people saying its a waist of money building these rear ends and to just go with an 8.8 or 9" rear conversion. Only issue is that's at least a couple more thousand I would have to throw in. Can I get this setup to hold the kind of power I need it to or am I better off spending the extra money and not have to do it twice.
06-15-2016, 02:55 PM
#2
I am in the process of building a rear end for my M6 GTO. Only issue is while doing research I have been seeing a lot of conflicting information about getting this rear end to hold 650 tq with an end goal of 750 tq. The car is my daily but I also like to take it to the track. I want to be able to throw some drag radials on it and run in the high 10s. My plan was to get a Tick Level 3 rebuild for my T56 and install a new clutch, Hinson driveshaft, DSS 1000HP axles and stubs, and TrueTrac or Kaaz diff. But now I am seeing a lot of people saying its a waist of money building these rear ends and to just go with an 8.8 or 9" rear conversion. Only issue is that's at least a couple more thousand I would have to throw in. Can I get this setup to hold the kind of power I need it to or am I better off spending the extra money and not have to do it twice.
8.8 and 9" kits have proven to be a waste of money and time in my opinion; at least in most applications. They increase NVH and the car is no longer a smooth drive; they add weight too.
A dedicated drag car with slicks running low 9's would be a good conversion. At that point, it might be a good idea for durability, repeatability and just longevity. In that case, there is a vendor here who makes a nice looking solid axle kit for the goat that I might consider looking into.
Save the 8.8 and 9" conversion for just a few percent of owners. 99% can make do with a stock diff, as long as it's built correctly.
06-16-2016, 09:44 PM
#3
Key to getting the stock drivetrain to live is going to be controlling the torque that the drivetrain actually sees.
If you have 750ft/lbs at the flywheel but choose a clutch that reaches it's slip point at 1000ft/lbs, that clutch can easily create 1000ft/lb torque spikes in spite of the 750ft/lb input...that may be more than your drivetrain can handle. If you instead choose a clutch with 800ft/lb capacity it will still handle the 750ft/lbs that you are making, but the torque spikes that are created (as the engine's WOT rpm is pulled down) will be limited to that clutch's 800ft/lb capacity.
An alternative is to choose the 1000ft/lb capacity clutch, but control the reserve capacity in such a way that it reduces the peak value of the torque spike that it creates...basically force it to slip longer. Simplified example is a clutch locking up at .3 seconds creating an additional 400ft/lb spike of energy recovered from the rotating assy as it loses rpm. If you delay that clutch's lockup until .6 seconds into the run you effectively released the same amount of energy from the rotating assy, but you doubled the duration over which that rpm loss occurred, which cuts the intensity in half. Simply put- you converted an energy release of 400ft/lbs over .3 seconds into 200ft/lbs over .6 seconds by simply delaying clutch lockup. I achieve this by attaching a small adjustable hydraulic cylinder onto my clutch pedal to delay the final bit of clutch lockup, but some install one-way restrictions in the slave cylinder line to slow engagement. One-way restrictions work fine if reaction time is not an issue, but a cylinder installed on the clutch pedal gets the job done without increasing R/T.
If you have 750ft/lbs at the flywheel but choose a clutch that reaches it's slip point at 1000ft/lbs, that clutch can easily create 1000ft/lb torque spikes in spite of the 750ft/lb input...that may be more than your drivetrain can handle. If you instead choose a clutch with 800ft/lb capacity it will still handle the 750ft/lbs that you are making, but the torque spikes that are created (as the engine's WOT rpm is pulled down) will be limited to that clutch's 800ft/lb capacity.
An alternative is to choose the 1000ft/lb capacity clutch, but control the reserve capacity in such a way that it reduces the peak value of the torque spike that it creates...basically force it to slip longer. Simplified example is a clutch locking up at .3 seconds creating an additional 400ft/lb spike of energy recovered from the rotating assy as it loses rpm. If you delay that clutch's lockup until .6 seconds into the run you effectively released the same amount of energy from the rotating assy, but you doubled the duration over which that rpm loss occurred, which cuts the intensity in half. Simply put- you converted an energy release of 400ft/lbs over .3 seconds into 200ft/lbs over .6 seconds by simply delaying clutch lockup. I achieve this by attaching a small adjustable hydraulic cylinder onto my clutch pedal to delay the final bit of clutch lockup, but some install one-way restrictions in the slave cylinder line to slow engagement. One-way restrictions work fine if reaction time is not an issue, but a cylinder installed on the clutch pedal gets the job done without increasing R/T.
06-17-2016, 01:47 PM
#6
absolutely, making adjustments in a chassis, driveline, driver style, etc will always help make you faster and more efficient. The clutch is one of them, rarely done right and blueprinted to what is optimal Imo. Hp/torque and race parts sell the clutch mostly.
06-24-2016, 09:31 PM
#7
Key to getting the stock drivetrain to live is going to be controlling the torque that the drivetrain actually sees.
If you have 750ft/lbs at the flywheel but choose a clutch that reaches it's slip point at 1000ft/lbs, that clutch can easily create 1000ft/lb torque spikes in spite of the 750ft/lb input...that may be more than your drivetrain can handle. If you instead choose a clutch with 800ft/lb capacity it will still handle the 750ft/lbs that you are making, but the torque spikes that are created (as the engine's WOT rpm is pulled down) will be limited to that clutch's 800ft/lb capacity.
An alternative is to choose the 1000ft/lb capacity clutch, but control the reserve capacity in such a way that it reduces the peak value of the torque spike that it creates...basically force it to slip longer. Simplified example is a clutch locking up at .3 seconds creating an additional 400ft/lb spike of energy recovered from the rotating assy as it loses rpm. If you delay that clutch's lockup until .6 seconds into the run you effectively released the same amount of energy from the rotating assy, but you doubled the duration over which that rpm loss occurred, which cuts the intensity in half. Simply put- you converted an energy release of 400ft/lbs over .3 seconds into 200ft/lbs over .6 seconds by simply delaying clutch lockup. I achieve this by attaching a small adjustable hydraulic cylinder onto my clutch pedal to delay the final bit of clutch lockup, but some install one-way restrictions in the slave cylinder line to slow engagement. One-way restrictions work fine if reaction time is not an issue, but a cylinder installed on the clutch pedal gets the job done without increasing R/T.
If you have 750ft/lbs at the flywheel but choose a clutch that reaches it's slip point at 1000ft/lbs, that clutch can easily create 1000ft/lb torque spikes in spite of the 750ft/lb input...that may be more than your drivetrain can handle. If you instead choose a clutch with 800ft/lb capacity it will still handle the 750ft/lbs that you are making, but the torque spikes that are created (as the engine's WOT rpm is pulled down) will be limited to that clutch's 800ft/lb capacity.
An alternative is to choose the 1000ft/lb capacity clutch, but control the reserve capacity in such a way that it reduces the peak value of the torque spike that it creates...basically force it to slip longer. Simplified example is a clutch locking up at .3 seconds creating an additional 400ft/lb spike of energy recovered from the rotating assy as it loses rpm. If you delay that clutch's lockup until .6 seconds into the run you effectively released the same amount of energy from the rotating assy, but you doubled the duration over which that rpm loss occurred, which cuts the intensity in half. Simply put- you converted an energy release of 400ft/lbs over .3 seconds into 200ft/lbs over .6 seconds by simply delaying clutch lockup. I achieve this by attaching a small adjustable hydraulic cylinder onto my clutch pedal to delay the final bit of clutch lockup, but some install one-way restrictions in the slave cylinder line to slow engagement. One-way restrictions work fine if reaction time is not an issue, but a cylinder installed on the clutch pedal gets the job done without increasing R/T.