BAC5.2 Posted February 21, 2011 Share Posted February 21, 2011 because at higher belt speeds air get "trapped" between the cogs on gear & teeth on belt creating a cushion , at low belt speeds the air can escape faster = less cushion . I don't think that's actually significant. Both sides are open, and there is insignificant windage inside the timing covers. Any contribution due to trapped air is likely so minimal, it can be neglected. Belt float in gear belts doesn't happen until EXTREMELY high speeds, which simply don't occur under the hood. rapid changes in speed/load wear both belt & sprocket faster , ie; stickshift car shifted quickly/hard would be expected to wear faster than auto car . I don't agree.\ Automatics do funky things when changing gears. One of which, at least in many applications, is cutting fuel to slow the engine down when your foot is planted at WOT. I'm not positive that Subarus do it, but that's about the most violent way to slow down an engine. stiffer valve springs or higher volume water pump on a subie will wear a belt faster That's definitely true. constantly changing , up down in belt speed will wear quicker than one that cruises at 3500 rpm forever , highway car vs city car That's marginal as well. Bearings are far more succeptible to wear from constantly changing RPM than gear belts are. The timing belts life is determined by miles, not operating hours or operating RPM. You could get to 105k by idling everywhere, or by spending the cars life above 6000 RPM. It makes no difference on the change interval. [URL="http://legacygt.com/forums/showthread.php/proper-flip-key-interesti-159894.html"]Flip Key Development Thread[/URL] "Genius may have its limitations, but stupidity is not thus handicapped." - E. Hubbard Link to comment Share on other sites More sharing options...
BAC5.2 Posted February 21, 2011 Share Posted February 21, 2011 No, sir. I'm not sure what "it spins more frequent" means. And if by "transients" you mean changes in acceleration, that's insignificant. You can't shift fast enough, and the car doesn't make enough power to accelerate fast enough. It's your money though. All of this is, of course, invalid if you have a Spec-B. Timing belts are a consumable, and should be inspected every fuel up, and replaced every oil change. [URL="http://legacygt.com/forums/showthread.php/proper-flip-key-interesti-159894.html"]Flip Key Development Thread[/URL] "Genius may have its limitations, but stupidity is not thus handicapped." - E. Hubbard Link to comment Share on other sites More sharing options...
Mr. Sinister Posted February 21, 2011 Share Posted February 21, 2011 All of this is, of course, invalid if you have a Spec-B. Timing belts are a consumable, and should be inspected every fuel up, and replaced every oil change. Why? I just throw the car in reverse to go back in time to when the belt was still new. Seriously though, I think the guys who mentioned severe duty and the maintenance schedule are correct. If manufacturers can milk more money out of the consumer, they would. I'd change it at the recommended interval unless everything was already apart for something else. Link to comment Share on other sites More sharing options...
LosAngelesLGT Posted February 21, 2011 Share Posted February 21, 2011 You are incorrect. ^Seems to indicate that you know SOMETHING. I should point out that my wife read this thread this morning and said "Does DrSharp know what a timing belt does?" ...I'm perfectly willing to listen to any well reasoned argument stating that timing belt "wear" is independent of driving intensity, but none have been presented here. Um... What? The easiest proof-in-point? The owners manual. There is no "severe duty" change interval. This is not something that changes from vehicle to vehicle. My Durango with all the HD towing options that drags boats from coast to coast and generators around hollywood does not have a more frequent timing belt change than any other with the same engine. Neither will the LGT with 404wtq. Link to comment Share on other sites More sharing options...
dr_sharp Posted February 21, 2011 Author Share Posted February 21, 2011 That must be why Subaru recommends a different timing belt change interval for different climates. I think they also recommend keeping the engine running between 2800 and 3600 rpm at all times. lol Link to comment Share on other sites More sharing options...
dr_sharp Posted February 21, 2011 Author Share Posted February 21, 2011 ^Seems to indicate that you know SOMETHING. I should point out that my wife read this thread this morning and said "Does DrSharp know what a timing belt does?" lol Link to comment Share on other sites More sharing options...
BAC5.2 Posted February 21, 2011 Share Posted February 21, 2011 It's your money. If you think think you drive the car SO hard that you need to replace it 20% sooner than Subaru recommends, then go for it. [/thread] [URL="http://legacygt.com/forums/showthread.php/proper-flip-key-interesti-159894.html"]Flip Key Development Thread[/URL] "Genius may have its limitations, but stupidity is not thus handicapped." - E. Hubbard Link to comment Share on other sites More sharing options...
LosAngelesLGT Posted February 21, 2011 Share Posted February 21, 2011 1) A timing belt does nothing more than... time the cams. It doesn't even do that in the AVCS and dual AVCS cars (not directly). The only torque the timing belt is exposed to is resistance from the cams and drag from the water pump and various idlers, which is shockingly little in relation to the design constraints of the belt. ^this and this thread is a waste of energy. What is the difference in driving around at 6000rpm and 2000rpm in 5th gear to the timing belt? How FAST you get to 105k miles. THATS IT. Timing belt float, cog wear? This is not a 16000rpm race bike. Link to comment Share on other sites More sharing options...
dr_sharp Posted February 21, 2011 Author Share Posted February 21, 2011 It's your money. If you think think you drive the car SO hard that you need to replace it 20% sooner than Subaru recommends, then go for it. [/thread] That statement is 100% agreeable to me. lol Link to comment Share on other sites More sharing options...
dr_sharp Posted February 21, 2011 Author Share Posted February 21, 2011 What is the difference in driving around at 6000rpm and 2000rpm in 5th gear to the timing belt? How FAST you get to 105k miles. EXACTLY Consider someone who drives at 2000 rpm to get to 105k miles. The timing belt experienced x number of cycles. Consider someone who drives at 6000 rpm (at the same speed, i.e. a different gear) to get to 105k miles. The timing belt experienced 3x number of cycles. So you could think of the timing belt as experiencing 3 times the wear... Now for those that are in an argumentative mood, I'm NOT saying I drive at 6,000 rpm everywhere, but I am saying that I row through the gears A LOT and don't 'cruise' very often. lol Link to comment Share on other sites More sharing options...
rao Posted February 21, 2011 Share Posted February 21, 2011 Sounds pretty bad-ass Rob IF YOU CARE ABOUT YOUR CAR YOU SHOULD NEVER DRIVE IT Link to comment Share on other sites More sharing options...
TankTread Posted February 21, 2011 Share Posted February 21, 2011 Changing timing belts is like skydiving...it may give you a rush to wait till the very end to pull the 'chute but it's an expensive mistake to wait too long. I would just say to check it often if you are going to be running it into high mileage situations. If you're going to get it wrong, better too soon than too late. BTW it's ridiculous to say that driving under hard acceleration does not put more stress on belts, tires, trans, or anything than a smooth and easy approach. Also, the "severe duty" section of manuals will never cater to customer's who beat their cars - that is up to the user to define when maintenance needs done. The manual is more of a guideline of typical part life. Just ask the NHRA top fuel team that doesn't rebuild the motor after each run how the next one will go. Link to comment Share on other sites More sharing options...
Mr. Sinister Posted February 21, 2011 Share Posted February 21, 2011 Consider someone who drives at 2000 rpm to get to 105k miles. The timing belt experienced x number of cycles. Consider someone who drives at 6000 rpm (at the same speed, i.e. a different gear) to get to 105k miles. The timing belt experienced 3x number of cycles. So you could think of the timing belt as experiencing 3 times the wear... You could also look at it from a different angle. 105K city miles is a lot more wear (lots of idling and stop-and-go) on the car than 105K highway. Yet, Subaru treats them both the same when it comes to replacement interval. Just like an extended warranty, if it gives you peace of mind, go ahead and do it. Link to comment Share on other sites More sharing options...
dr_sharp Posted February 21, 2011 Author Share Posted February 21, 2011 Sounds pretty bad-ass A well reasoned argument is badass... you should try it sometime. lol Link to comment Share on other sites More sharing options...
rao Posted February 21, 2011 Share Posted February 21, 2011 I am taking notes on this thread and I will see if I can manage it. Rob IF YOU CARE ABOUT YOUR CAR YOU SHOULD NEVER DRIVE IT Link to comment Share on other sites More sharing options...
dr_sharp Posted February 21, 2011 Author Share Posted February 21, 2011 I am taking notes on this thread and I will see if I can manage it. I don't think you can. lol Link to comment Share on other sites More sharing options...
rao Posted February 21, 2011 Share Posted February 21, 2011 Probably not, but maybe some day if I try really, really hard. In the meantime I need to go and change my timing belt. Rob IF YOU CARE ABOUT YOUR CAR YOU SHOULD NEVER DRIVE IT Link to comment Share on other sites More sharing options...
dr_sharp Posted February 21, 2011 Author Share Posted February 21, 2011 Probably not, but maybe some day if I try really, really hard. In the meantime I need to go and change my timing belt. How many miles do you have on the current one? Do you drive your car hard? lol Link to comment Share on other sites More sharing options...
LosAngelesLGT Posted February 21, 2011 Share Posted February 21, 2011 Consider someone who drives at 2000 rpm to get to 105k miles. The timing belt experienced x number of cycles. Consider someone who drives at 6000 rpm (at the same speed, i.e. a different gear) to get to 105k miles. The timing belt experienced 3x number of cycles. So you could think of the timing belt as experiencing 3 times the wear... GRADE SCHOOL MATH BRO! You are making it impossible to be nice about this boyo. (2000rpm)x=105k miles where x = the amount of time it takes to reach 105k @ 2000rpm (6000rpm)y =105k miles where y = the amount of time it takes to reach 105k @ 6000rpm "Y" will reach 105k miles 3 times FASTER than "X" foolio. NOT 3 times as much wear. 2000rpm in 5th gear is a lot slower than 6000rpm. I stated both cars are in the SAME gear. The timing belt experienced THE EXACT SAME NUMBER OF CYCLES. What is so difficult to understand? EDIT: No matter how much throttle you give it, no matter how many rpm you drive at, if we all drive in the same gear, the car will take the exact same amout of cycles to reach 105k miles. Link to comment Share on other sites More sharing options...
motorbykemike Posted February 21, 2011 Share Posted February 21, 2011 Changing timing belts is like skydiving...it may give you a rush to wait till the very end to pull the 'chute but it's an expensive mistake to wait too long. I would just say to check it often if you are going to be running it into high mileage situations. If you're going to get it wrong, better too soon than too late. BTW it's ridiculous to say that driving under hard acceleration does not put more stress on belts, tires, trans, or anything than a smooth and easy approach. Also, the "severe duty" section of manuals will never cater to customer's who beat their cars - that is up to the user to define when maintenance needs done. The manual is more of a guideline of typical part life. Just ask the NHRA top fuel team that doesn't rebuild the motor after each run how the next one will go. well said Link to comment Share on other sites More sharing options...
LosAngelesLGT Posted February 21, 2011 Share Posted February 21, 2011 ^meaningless post. This thread is about TIMING BELTS not NHRA. A timing belt does nothing more than... time the cams. It doesn't even do that in the AVCS and dual AVCS cars (not directly). The only torque the timing belt is exposed to is resistance from the cams and drag from the water pump and various idlers, which is shockingly little in relation to the design constraints of the belt. ^This. yet again. Link to comment Share on other sites More sharing options...
mattg Posted February 21, 2011 Share Posted February 21, 2011 I have the Gates kevlar belt. If I had to do it over again I would go with the OEM STi belt and all OEM accessories including water pump. Link to comment Share on other sites More sharing options...
rao Posted February 21, 2011 Share Posted February 21, 2011 ^meaningless post. This thread is about TIMING BELTS not NHRA. Besides, I have read that Subaru's are not well suited to the 1/4 mile. Rob IF YOU CARE ABOUT YOUR CAR YOU SHOULD NEVER DRIVE IT Link to comment Share on other sites More sharing options...
BAC5.2 Posted February 21, 2011 Share Posted February 21, 2011 Changing timing belts is like skydiving...it may give you a rush to wait till the very end to pull the 'chute but it's an expensive mistake to wait too long. I would just say to check it often if you are going to be running it into high mileage situations. If you're going to get it wrong, better too soon than too late. BTW it's ridiculous to say that driving under hard acceleration does not put more stress on belts, tires, trans, or anything than a smooth and easy approach. Also, the "severe duty" section of manuals will never cater to customer's who beat their cars - that is up to the user to define when maintenance needs done. The manual is more of a guideline of typical part life. Just ask the NHRA top fuel team that doesn't rebuild the motor after each run how the next one will go. You need to read this thread. http://www.legacygt.com/forums/showthread.php?t=108079 [URL="http://legacygt.com/forums/showthread.php/proper-flip-key-interesti-159894.html"]Flip Key Development Thread[/URL] "Genius may have its limitations, but stupidity is not thus handicapped." - E. Hubbard Link to comment Share on other sites More sharing options...
dr_sharp Posted February 21, 2011 Author Share Posted February 21, 2011 Besides, I have read that Subaru's are not well suited to the 1/4 mile. Did Car & Driver tell you that? lol Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.