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SVT Shelby GT500
2012 Gt500 Goes into gear, but wont move forward
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<blockquote data-quote="Bad Company" data-source="post: 16991987" data-attributes="member: 141815"><p>Yes you can float shift while downshifting. Why I don't think he is doing this is he would have to match/raise engine RPM for the gear being chosen as you move the stick through neutral.</p><p></p><p>As you remove torque from the driveline and you float the driveline the stick will easily move into neutral without using the clutch, now to make the downshift without grinding the synchronizer you have to increase the speed of the gear you're choosing next by raising engine rpm with the transmission in neutral. Look at it in this manner, synchronizers are nothing more than mini clutches inside the transmission that use friction to either speed up the next gear of your choice or by slowing it down as your moving the stick from one gear to the next. This is why when a synchronizer becomes worn that the transmission makes noise during the shifting process.</p><p></p><p>Now if the car being talked about by the OP has a failure in one of the CV joints in the driveshaft, he has removed all of the load while he is seeing his speedometer increasing in speed as he goes through the gears. Without load on the gears he should be able to upshift easily if he works the throttle in the same manner as he would on the street while moving, so he would naturally be dropping the speed of the next upshift gear and the synchronizer wouldn't have too much load on it that to match the speed for the next gear chosen. Now if he is sitting there upshifting gears without using the throttle the synchronizer has much more work to do in matching gears. I'm assuming that during his tests that he trying to get the car to move and its not and he is watching his speedometer increase in it speed readings as if he was driving down a street. So he would instinctively manipulate the throttle in the same manner as if he were driving. If he is doing this then he would be slowing the next gear for the upshift down naturally giving the synchronizer less work to do to match speeds inside of the transmission for an easy upshift. Why don't I feel that the OP would be able to make the downshifts without making noise or grinding is the fact I don't think he is raising engine RPM while moving the stick through neutral to speed up the lower gear chosen. </p><p></p><p>All Class 8 trucks up until a few years aga don't have synchronizers in them. The recommended method to shift is to push in the clutch, move the stick to neutral, release the clutch, raise or lower engine RPM to either speed up the gears or slowdown the speed of the gears inside of the transmission to then select the gear you want. Now if you matched the speed of the gear selected to the road speed you're traveling and the engine RPM you push the clutch down and move the stick to the gear chosen. If you didn't match the engine RPM for the gear chosen in your mind that you are going to then the transmission is going to grind and you won't be able to proceed with the shift........now what do you do next? Try it all over again until you match the gear to the road speed your traveling with the engine RPM so the stick drops into gear without clashing. In a truck the shifter is moving what is known as a sliding clutch in the transmission from one gear to the next, not a synchronizer, why? Because it doesn't have the extra friction ring in it to speed up or slowdown the next gear. It takes a new driver 10s of thousands of miles to become proficient in doing this. Today many trucks are built with a manual transmission with a computer that talks to the engine computer to complete the shift automatically. Here are two YouTube links of the new automated manual transmissions being tested by drivers with many years of experience driving traditional non-synchronized transmissions. Unfortunately many of the new drivers today can't drive a truck with a traditional stick shift transmission and their driver's license is restricted to them only driving a truck with one of these automated manual transmissions in it. Because it is a long learning process to shift a manual and no two trucks really shift exactly the same it really can take years to do correctly. Older trucks can actually have more than one transmission in them. The main and the auxilary in the worst possible gear combination to learn is a 18 speed main with a 4 speed auxilary behind the main for a total of 72 gears to chose from. This set up is used strictly for extreme Heavy Haul or Off-Road Oil Field Drill support equipment. The biggest combination I have had the opportunity to see was a 21 axle combination truck and trailer that was weighing 600,000lbs. It was having an engine problem with the main tractor and I had to look at it on the side of the road at the bottom of Afton mountain on I64. To move the truck engine was modified roughly to 1000Hp, the trailer had a 600Hp pusher engine controlled from the cab of the truck followed by a 1200Hp push truck to help going over the hills. Transmissions used in this combination was a 18 speed with a 4 speed air shifted auxillary. The auxillary had a stick that didn't move, it had a knob on the top of the stick with the 4 different possibilities at the flick of a switch to shift. Now float shifting this combination is something I wouldn't even begin to try without a lot of training from the driver that was driving it. These two stick/transmission set ups came about in the 50s-60s when you had very low Hp either gas or diesel engines and used transmissions to multiply torque. </p><p></p><p> [MEDIA=youtube]gFzjjfvsmuw[/MEDIA]</p><p></p><p>[MEDIA=youtube]ScRKBHe88uo[/MEDIA]</p></blockquote><p></p>
[QUOTE="Bad Company, post: 16991987, member: 141815"] Yes you can float shift while downshifting. Why I don't think he is doing this is he would have to match/raise engine RPM for the gear being chosen as you move the stick through neutral. As you remove torque from the driveline and you float the driveline the stick will easily move into neutral without using the clutch, now to make the downshift without grinding the synchronizer you have to increase the speed of the gear you're choosing next by raising engine rpm with the transmission in neutral. Look at it in this manner, synchronizers are nothing more than mini clutches inside the transmission that use friction to either speed up the next gear of your choice or by slowing it down as your moving the stick from one gear to the next. This is why when a synchronizer becomes worn that the transmission makes noise during the shifting process. Now if the car being talked about by the OP has a failure in one of the CV joints in the driveshaft, he has removed all of the load while he is seeing his speedometer increasing in speed as he goes through the gears. Without load on the gears he should be able to upshift easily if he works the throttle in the same manner as he would on the street while moving, so he would naturally be dropping the speed of the next upshift gear and the synchronizer wouldn't have too much load on it that to match the speed for the next gear chosen. Now if he is sitting there upshifting gears without using the throttle the synchronizer has much more work to do in matching gears. I'm assuming that during his tests that he trying to get the car to move and its not and he is watching his speedometer increase in it speed readings as if he was driving down a street. So he would instinctively manipulate the throttle in the same manner as if he were driving. If he is doing this then he would be slowing the next gear for the upshift down naturally giving the synchronizer less work to do to match speeds inside of the transmission for an easy upshift. Why don't I feel that the OP would be able to make the downshifts without making noise or grinding is the fact I don't think he is raising engine RPM while moving the stick through neutral to speed up the lower gear chosen. All Class 8 trucks up until a few years aga don't have synchronizers in them. The recommended method to shift is to push in the clutch, move the stick to neutral, release the clutch, raise or lower engine RPM to either speed up the gears or slowdown the speed of the gears inside of the transmission to then select the gear you want. Now if you matched the speed of the gear selected to the road speed you're traveling and the engine RPM you push the clutch down and move the stick to the gear chosen. If you didn't match the engine RPM for the gear chosen in your mind that you are going to then the transmission is going to grind and you won't be able to proceed with the shift........now what do you do next? Try it all over again until you match the gear to the road speed your traveling with the engine RPM so the stick drops into gear without clashing. In a truck the shifter is moving what is known as a sliding clutch in the transmission from one gear to the next, not a synchronizer, why? Because it doesn't have the extra friction ring in it to speed up or slowdown the next gear. It takes a new driver 10s of thousands of miles to become proficient in doing this. Today many trucks are built with a manual transmission with a computer that talks to the engine computer to complete the shift automatically. Here are two YouTube links of the new automated manual transmissions being tested by drivers with many years of experience driving traditional non-synchronized transmissions. Unfortunately many of the new drivers today can't drive a truck with a traditional stick shift transmission and their driver's license is restricted to them only driving a truck with one of these automated manual transmissions in it. Because it is a long learning process to shift a manual and no two trucks really shift exactly the same it really can take years to do correctly. Older trucks can actually have more than one transmission in them. The main and the auxilary in the worst possible gear combination to learn is a 18 speed main with a 4 speed auxilary behind the main for a total of 72 gears to chose from. This set up is used strictly for extreme Heavy Haul or Off-Road Oil Field Drill support equipment. The biggest combination I have had the opportunity to see was a 21 axle combination truck and trailer that was weighing 600,000lbs. It was having an engine problem with the main tractor and I had to look at it on the side of the road at the bottom of Afton mountain on I64. To move the truck engine was modified roughly to 1000Hp, the trailer had a 600Hp pusher engine controlled from the cab of the truck followed by a 1200Hp push truck to help going over the hills. Transmissions used in this combination was a 18 speed with a 4 speed air shifted auxillary. The auxillary had a stick that didn't move, it had a knob on the top of the stick with the 4 different possibilities at the flick of a switch to shift. Now float shifting this combination is something I wouldn't even begin to try without a lot of training from the driver that was driving it. These two stick/transmission set ups came about in the 50s-60s when you had very low Hp either gas or diesel engines and used transmissions to multiply torque. [MEDIA=youtube]gFzjjfvsmuw[/MEDIA] [MEDIA=youtube]ScRKBHe88uo[/MEDIA] [/QUOTE]
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2012 Gt500 Goes into gear, but wont move forward
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