Cryo axles and hubs. Worth it??
02-08-2011, 03:52 AM
#1
Rennlist Member
Thread Starter
Cryo axles and hubs. Worth it??
I am about to put in a powerful new motor and am concerned over the hubs and axles and was thinking of having some spare ones cryo treated just to hopefully add some preventative insurance. Perhaps it's a pipe dream but who knows, it might be worth it.
Does any retailer of these parts offer this service?
btw this is for a 951.
Does any retailer of these parts offer this service?
btw this is for a 951.
02-08-2011, 10:21 AM
#4
Rennlist Member
http://www.diversifiedcryogenics.com/motorsports.html
Spindles might be worth asking about. But, would probably be better off going with the Racers Edge machined hubs.
Spindles might be worth asking about. But, would probably be better off going with the Racers Edge machined hubs.
02-08-2011, 11:21 AM
#5
Rennlist Member
Thread Starter
Juan, I am also working on another transmission option which we've also spoken about adapting 911 hubs, so perhaps your friends might make us something to work with?
Jim, I have the whole box and dice from Karl. Arms, hubs, bushings etc.
Also, in your opinion, what would provide more torque load on a trans / driveline components? The 951 S box with stock gearing or with shorter gearing as per S2 ring and pinion? Think of a 3.1 motor with a big turbo up front. We're using the 951 trans for now but trying to reduce the torque loading but I'm not sure which final drive would put more or less strain on everything. The S2 will mean it revs faster, but perhaps with less time for the torque to develop as much and visa versa...???
http://www.diversifiedcryogenics.com/motorsports.html
Spindles might be worth asking about. But, would probably be better off going with the Racers Edge machined hubs.
Spindles might be worth asking about. But, would probably be better off going with the Racers Edge machined hubs.
Also, in your opinion, what would provide more torque load on a trans / driveline components? The 951 S box with stock gearing or with shorter gearing as per S2 ring and pinion? Think of a 3.1 motor with a big turbo up front. We're using the 951 trans for now but trying to reduce the torque loading but I'm not sure which final drive would put more or less strain on everything. The S2 will mean it revs faster, but perhaps with less time for the torque to develop as much and visa versa...???
02-08-2011, 12:38 PM
#6
Rennlist Member
The transmission guts on the turbo and S2 trans are the same ratios (other than the stock S2 5th), so the internals will transmit the same magnitude of torque from the flywheel thru to the R/P.
The S2 has a 14.8% shorter ratio, so the output shafts transmit 14.8% higher torque at a given engine rpm and in a given gear.
Generally, for road course use, comparing the two R/Ps, the torque loading on the axles will average out over time with the variation in engine rpm, torque at rpm, vehicle speed and gear selection. But there will be some additional risk of snapping an axle or busting a CV joint, if doing a lot of hard 2nd gear pulls coming out of tight turns with the S2 R/P vs a Turbo R/P, w/ a high torque motor.
And there is a difference in strength between the gear teeth on the Turbo R/P vs. the teeth on the S2 R/P. Side by side the 8:27 Turbo teeth are larger than the 8:31 teeth on the S2. And, assuming equal material properties and equal heat treat, the larger cross sectional area of the tooth roots on the Turbo R/P will be somewhat stronger than the S2.
The actual head of the Turbo pinion is slightly larger diameter than the S2 pinion. So with a given torque on that shaft, the force acting on the face of the turbo tooth is less than the force on the S2 tooth by the ratio of the different pitch (tooth contact point) radii. I would guess these tooth dimensional differences would equate to approximately the same 15% ratio difference.
Although maybe 15% weaker, is the S2 R/P still strong enough to last? Will something else always fail first? Axle, clutch, etc? I think there would be a little higher/faster tooth wear on the S2 R/P, due to the higher tooth contact forces. But it still may not lead to any need for premature replacements, as S2 R/Ps do have a good history of working in higher hp turbo applications.
Interesting question, had not really thought about this before.
The S2 has a 14.8% shorter ratio, so the output shafts transmit 14.8% higher torque at a given engine rpm and in a given gear.
Generally, for road course use, comparing the two R/Ps, the torque loading on the axles will average out over time with the variation in engine rpm, torque at rpm, vehicle speed and gear selection. But there will be some additional risk of snapping an axle or busting a CV joint, if doing a lot of hard 2nd gear pulls coming out of tight turns with the S2 R/P vs a Turbo R/P, w/ a high torque motor.
And there is a difference in strength between the gear teeth on the Turbo R/P vs. the teeth on the S2 R/P. Side by side the 8:27 Turbo teeth are larger than the 8:31 teeth on the S2. And, assuming equal material properties and equal heat treat, the larger cross sectional area of the tooth roots on the Turbo R/P will be somewhat stronger than the S2.
The actual head of the Turbo pinion is slightly larger diameter than the S2 pinion. So with a given torque on that shaft, the force acting on the face of the turbo tooth is less than the force on the S2 tooth by the ratio of the different pitch (tooth contact point) radii. I would guess these tooth dimensional differences would equate to approximately the same 15% ratio difference.
Although maybe 15% weaker, is the S2 R/P still strong enough to last? Will something else always fail first? Axle, clutch, etc? I think there would be a little higher/faster tooth wear on the S2 R/P, due to the higher tooth contact forces. But it still may not lead to any need for premature replacements, as S2 R/Ps do have a good history of working in higher hp turbo applications.
Interesting question, had not really thought about this before.
02-08-2011, 01:29 PM
#7
Drifting
The purpose of a treatment like this is to increase the compressive residual stresses at the surface of the material with the goal of improved fatigue life. You may be better off having your hubs and axles shotpeened. It's a tried and true practice, and I think there is a lot more expertise and research behind it than cryo.
As for the transmission parts I would look into REM Isotropic finishing or MicroTec Finishing. I have examined parts from both processes (including viewing with an electron microscope) and the surface improvements are significant. There is a good amount of documentation on REM finishing reducing the occurence of contact fatigue in gears systems. These finishing methods are in use by a lot of pro teams, including F1.
Without proper testing you won't be able to quantify the increase in fatigue life of your parts, but these are well understood processes that can make your parts last longer and give you a little insurance against premature failures.
As for the transmission parts I would look into REM Isotropic finishing or MicroTec Finishing. I have examined parts from both processes (including viewing with an electron microscope) and the surface improvements are significant. There is a good amount of documentation on REM finishing reducing the occurence of contact fatigue in gears systems. These finishing methods are in use by a lot of pro teams, including F1.
Without proper testing you won't be able to quantify the increase in fatigue life of your parts, but these are well understood processes that can make your parts last longer and give you a little insurance against premature failures.
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02-09-2011, 03:18 AM
#10
Rennlist Member
Thread Starter
The transmission guts on the turbo and S2 trans are the same ratios (other than the stock S2 5th), so the internals will transmit the same magnitude of torque from the flywheel thru to the R/P.
The S2 has a 14.8% shorter ratio, so the output shafts transmit 14.8% higher torque at a given engine rpm and in a given gear.
Generally, for road course use, comparing the two R/Ps, the torque loading on the axles will average out over time with the variation in engine rpm, torque at rpm, vehicle speed and gear selection. But there will be some additional risk of snapping an axle or busting a CV joint, if doing a lot of hard 2nd gear pulls coming out of tight turns with the S2 R/P vs a Turbo R/P, w/ a high torque motor.
And there is a difference in strength between the gear teeth on the Turbo R/P vs. the teeth on the S2 R/P. Side by side the 8:27 Turbo teeth are larger than the 8:31 teeth on the S2. And, assuming equal material properties and equal heat treat, the larger cross sectional area of the tooth roots on the Turbo R/P will be somewhat stronger than the S2.
The actual head of the Turbo pinion is slightly larger diameter than the S2 pinion. So with a given torque on that shaft, the force acting on the face of the turbo tooth is less than the force on the S2 tooth by the ratio of the different pitch (tooth contact point) radii. I would guess these tooth dimensional differences would equate to approximately the same 15% ratio difference.
Although maybe 15% weaker, is the S2 R/P still strong enough to last? Will something else always fail first? Axle, clutch, etc? I think there would be a little higher/faster tooth wear on the S2 R/P, due to the higher tooth contact forces. But it still may not lead to any need for premature replacements, as S2 R/Ps do have a good history of working in higher hp turbo applications.
Interesting question, had not really thought about this before.
The S2 has a 14.8% shorter ratio, so the output shafts transmit 14.8% higher torque at a given engine rpm and in a given gear.
Generally, for road course use, comparing the two R/Ps, the torque loading on the axles will average out over time with the variation in engine rpm, torque at rpm, vehicle speed and gear selection. But there will be some additional risk of snapping an axle or busting a CV joint, if doing a lot of hard 2nd gear pulls coming out of tight turns with the S2 R/P vs a Turbo R/P, w/ a high torque motor.
And there is a difference in strength between the gear teeth on the Turbo R/P vs. the teeth on the S2 R/P. Side by side the 8:27 Turbo teeth are larger than the 8:31 teeth on the S2. And, assuming equal material properties and equal heat treat, the larger cross sectional area of the tooth roots on the Turbo R/P will be somewhat stronger than the S2.
The actual head of the Turbo pinion is slightly larger diameter than the S2 pinion. So with a given torque on that shaft, the force acting on the face of the turbo tooth is less than the force on the S2 tooth by the ratio of the different pitch (tooth contact point) radii. I would guess these tooth dimensional differences would equate to approximately the same 15% ratio difference.
Although maybe 15% weaker, is the S2 R/P still strong enough to last? Will something else always fail first? Axle, clutch, etc? I think there would be a little higher/faster tooth wear on the S2 R/P, due to the higher tooth contact forces. But it still may not lead to any need for premature replacements, as S2 R/Ps do have a good history of working in higher hp turbo applications.
Interesting question, had not really thought about this before.
The purpose of a treatment like this is to increase the compressive residual stresses at the surface of the material with the goal of improved fatigue life. You may be better off having your hubs and axles shotpeened. It's a tried and true practice, and I think there is a lot more expertise and research behind it than cryo.
As for the transmission parts I would look into REM Isotropic finishing or MicroTec Finishing. I have examined parts from both processes (including viewing with an electron microscope) and the surface improvements are significant. There is a good amount of documentation on REM finishing reducing the occurence of contact fatigue in gears systems. These finishing methods are in use by a lot of pro teams, including F1.
Without proper testing you won't be able to quantify the increase in fatigue life of your parts, but these are well understood processes that can make your parts last longer and give you a little insurance against premature failures.
As for the transmission parts I would look into REM Isotropic finishing or MicroTec Finishing. I have examined parts from both processes (including viewing with an electron microscope) and the surface improvements are significant. There is a good amount of documentation on REM finishing reducing the occurence of contact fatigue in gears systems. These finishing methods are in use by a lot of pro teams, including F1.
Without proper testing you won't be able to quantify the increase in fatigue life of your parts, but these are well understood processes that can make your parts last longer and give you a little insurance against premature failures.
Link? I couldn't see it.
Thanks Juan it should prove interesting.
