TNBrett
Full Access Member
I’m running Royal Purple Synchromax in my ZF5. I haven’t checked the temperature when towing, but I know it gets too hot to touch. I believe this to be normal in pretty much any manual transmission. There may not be clutches slipping inside like in an automatic, but you’re still putting a whole lot of energy through it.
If we think about things in terms of efficiency perhaps it will make more sense. Let’s assume that an automatic transmission is 90% efficient (I know it’s not, but just for discussion). That would mean that 90% of the power your engine makes actually makes it out of the transmission and down the driveshaft. The other 10% is almost entirely converted into heat. In an automatic transmission, the fluid is pumped through coolers which work to dump all of that excess heat out side of the system. When everything works as it should heat build up is kept at a safe level and your transmission lives a happy life. The problem in automatic transmissions is when you create more heat than the cooling system can get rid of. More load, more speed, and more power can all lead to more heat.
If we look at a manual transmission, maybe we assume 99% efficiency (again, I made that up for discussion). It is much more efficient at transferring that energy from the engine to the drive shaft, but no mechanical system is 100% efficient. That 1% is still converted into heat. The difference is that most manual transmissions have no means of rejecting that heat other than what radiates off the case of the transmission. And when you pull more weight, faster, and with more horsepower, you’re still adding more heat.
I really do like the idea of the Fast Cooler for the ZF5. It seems like a pretty simple solution that would certainly help get rid of some heat. I like the idea of increased oil capacity without a necessarily higher oil level as well. Though it does mean about $40 more in oil with the Royal Purple.
As far as the “jumpiness” goes, I think it’s a clutch issue. Mine does it as well. When I start out in the morning, clutch engagement is nice and smooth. But, once everything gets heat soaked, 1st and reverse are pretty jumpy or grabby. All the other shifts are just fine. I have a Luk SMF as well. Sadly, my truck is waiting for me to pull the engine out. I’ll do head gaskets and studs, and try and get to the bottom of the jumpy clutch. I’m expecting to find some evidence of hot spots or heat cracking, or maybe just some trashed buffer springs in the clutch disk. We shall see.
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If we think about things in terms of efficiency perhaps it will make more sense. Let’s assume that an automatic transmission is 90% efficient (I know it’s not, but just for discussion). That would mean that 90% of the power your engine makes actually makes it out of the transmission and down the driveshaft. The other 10% is almost entirely converted into heat. In an automatic transmission, the fluid is pumped through coolers which work to dump all of that excess heat out side of the system. When everything works as it should heat build up is kept at a safe level and your transmission lives a happy life. The problem in automatic transmissions is when you create more heat than the cooling system can get rid of. More load, more speed, and more power can all lead to more heat.
If we look at a manual transmission, maybe we assume 99% efficiency (again, I made that up for discussion). It is much more efficient at transferring that energy from the engine to the drive shaft, but no mechanical system is 100% efficient. That 1% is still converted into heat. The difference is that most manual transmissions have no means of rejecting that heat other than what radiates off the case of the transmission. And when you pull more weight, faster, and with more horsepower, you’re still adding more heat.
I really do like the idea of the Fast Cooler for the ZF5. It seems like a pretty simple solution that would certainly help get rid of some heat. I like the idea of increased oil capacity without a necessarily higher oil level as well. Though it does mean about $40 more in oil with the Royal Purple.
As far as the “jumpiness” goes, I think it’s a clutch issue. Mine does it as well. When I start out in the morning, clutch engagement is nice and smooth. But, once everything gets heat soaked, 1st and reverse are pretty jumpy or grabby. All the other shifts are just fine. I have a Luk SMF as well. Sadly, my truck is waiting for me to pull the engine out. I’ll do head gaskets and studs, and try and get to the bottom of the jumpy clutch. I’m expecting to find some evidence of hot spots or heat cracking, or maybe just some trashed buffer springs in the clutch disk. We shall see.
Sent from my iPhone using Tapatalk
