Rubber Band Timing Belt?
03-11-2010, 01:30 PM
#32
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Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
03-11-2010, 02:08 PM
#33
Rennlist Member
Again, ive had both (oil in it and no or little oil in it) the warning still comes on. the wiring is suspect as it attached to the harness. Ive replaced all the components in that area, but the main plug, which is attached to the harness. I still think that is the issue, though I soldered what was left of the poor thing together. By the way, ive always filled it the correct way, through the filler fittings and with gravity.
my defintion of "dampner" is first of all its "DAMPER" and second its something that can reduce oscillations. Yes, i understand the concept, if you have a fluid tight seal, for which I dont think really exisits. fluid is free to escape to the sides of the discs, which might effect the ability of the system to damp the ocsillations. You make it sound like its a shock absorber, and it really is not as first of all, there is a minor amount of movement, and the movement of the discs, even under compression, is effected very little by the oil in the cylinder. even if there was, i have used the system with oil in it, and the warning still comes on . the belts have been changed often, and Ive never had an issue with a loose belt. either has scot. Personally, i think the fluid is for corrosion resistance, and heat transfer speed, for which I just make sure i go easy on the engine until its fully heat soaked. There is a connection that is suspect, if there wasnt, and the FACT that ive never had the warning light NOT come on in 10 years, should tell you that this is probably electrical, especially since I have had oil in it at one time as well. all the components have been checked out several times. again, the only thing that is NOT new or doesnt look good from a contact perspective, is the main connection and wire from the harness. The fluid leaked out due to the front seal being old, plus a combination of different years parts havent helped the fit of everything. so,I guess a new front seal would be in order, but now with it about half fill with oil, its not a concern and doesnt leak.
Anyway, the belt is at 5.0 and is checked fairly regularly.
Again, much of this is speculation, until we get some high speed cameras on the system with and without oil.
Here again, ive proved it over 10 years of a full racing schedule, never missing a race, but I guess Im just lucky here too.
my defintion of "dampner" is first of all its "DAMPER" and second its something that can reduce oscillations. Yes, i understand the concept, if you have a fluid tight seal, for which I dont think really exisits. fluid is free to escape to the sides of the discs, which might effect the ability of the system to damp the ocsillations. You make it sound like its a shock absorber, and it really is not as first of all, there is a minor amount of movement, and the movement of the discs, even under compression, is effected very little by the oil in the cylinder. even if there was, i have used the system with oil in it, and the warning still comes on . the belts have been changed often, and Ive never had an issue with a loose belt. either has scot. Personally, i think the fluid is for corrosion resistance, and heat transfer speed, for which I just make sure i go easy on the engine until its fully heat soaked. There is a connection that is suspect, if there wasnt, and the FACT that ive never had the warning light NOT come on in 10 years, should tell you that this is probably electrical, especially since I have had oil in it at one time as well. all the components have been checked out several times. again, the only thing that is NOT new or doesnt look good from a contact perspective, is the main connection and wire from the harness. The fluid leaked out due to the front seal being old, plus a combination of different years parts havent helped the fit of everything. so,I guess a new front seal would be in order, but now with it about half fill with oil, its not a concern and doesnt leak.
Anyway, the belt is at 5.0 and is checked fairly regularly.
Again, much of this is speculation, until we get some high speed cameras on the system with and without oil.
Here again, ive proved it over 10 years of a full racing schedule, never missing a race, but I guess Im just lucky here too.
To correct your misconception of whethere there is damping available in the tensioner: There is. WHEN THERE IS OIL IN THE TENSIONER, there's a check valve that allows oil to flow freely into the cavity under the piston, but closes to limit flow going out. Result is that the piston can extend easily as the belt gets loose, but is harder to compress when tension increases. To my knowledge and experience, this is a dampener. Perhaps your definitions are different?
Why did the oil leak out of the shaft seal? This failure is common if the tensioner is filled using too much pressure, AND ESPECIALLY IF FILLING THROUGH THE WRONG PORT, since that will fill the top cavity before the bottom, and the check valve prevents flow that way.
The electrical-- You know for a fact that the sensor switch did not function from the time you obtained the car. You've replaced the belt a couple times now, including moving the tensioner and switch unit from the old engine to the new stroker engine, and moving that new engine from the oldcar to the new one. Can I suppose that it never crossed your mind at any of those times to peek at the switch/spring/contacts at the end of the tensioner plunger and see what might be wrong? What might be causing the "!!Check Toothed Belt!!" warning message to shout at you in bright red? If the temp gauge went to full hot, or the oil pressure dropped and the warning lights came on, would you continue driving until you saw steam or heard the rod bearings rattling? "I don't know why the car blew up, dad. I was driving it the way I always do, with the all the warning lights on, then BOOM clank clank clank... It shouldn't have broken. After all, I've RACED it for years with those warning lights on, and racing is the only true test of durability." Does this sound as brilliant to other folks as it does to me?
Why did the oil leak out of the shaft seal? This failure is common if the tensioner is filled using too much pressure, AND ESPECIALLY IF FILLING THROUGH THE WRONG PORT, since that will fill the top cavity before the bottom, and the check valve prevents flow that way.
The electrical-- You know for a fact that the sensor switch did not function from the time you obtained the car. You've replaced the belt a couple times now, including moving the tensioner and switch unit from the old engine to the new stroker engine, and moving that new engine from the oldcar to the new one. Can I suppose that it never crossed your mind at any of those times to peek at the switch/spring/contacts at the end of the tensioner plunger and see what might be wrong? What might be causing the "!!Check Toothed Belt!!" warning message to shout at you in bright red? If the temp gauge went to full hot, or the oil pressure dropped and the warning lights came on, would you continue driving until you saw steam or heard the rod bearings rattling? "I don't know why the car blew up, dad. I was driving it the way I always do, with the all the warning lights on, then BOOM clank clank clank... It shouldn't have broken. After all, I've RACED it for years with those warning lights on, and racing is the only true test of durability." Does this sound as brilliant to other folks as it does to me?
03-11-2010, 02:34 PM
#35
Rennlist Member
This is something I just havent done. again, Ive replaced the main socket connector, thinking that was bad, but the main input wire has always been suspect. So, I guess the wire connection just have continuity with ground. break the connection and the existing wire should show open to ground. trace it back to the computer and see if the same thing happens there.
maybe ill just wire a little light bulb and attach it to the known good tensioner socket. as soon as the light goes out, we know we have fluttering, and it wont have delay or computer issues a all. It will a way to actually "see" the connection or the system in action. hows that?
mk
[QUOTE=dr bob;7380280]Mark, It probably is electrical. That's the darn tension monitoring system for you. Belt loose or flapping, there's an electrical connection that opens and turns the light on. Pull the wire and that same circuit is opened and, miracle!!!, the light comes on. Stop the flapping by adding oil to the tensioner. Verify the correct assembly of the tensioner and the spring and contacts in the switch. When you get the belt on and the tension set, but before you button all the covers on, test the tesnion monitoring circuit with an ohm meter. If you have an open circuit to ground from the pigtail, the switch is not assembled correctly. If it's closed to ground it's OK to assemble, and you know it's working. All before the covers go on, imagine that.
maybe ill just wire a little light bulb and attach it to the known good tensioner socket. as soon as the light goes out, we know we have fluttering, and it wont have delay or computer issues a all. It will a way to actually "see" the connection or the system in action. hows that?
mk
[QUOTE=dr bob;7380280]Mark, It probably is electrical. That's the darn tension monitoring system for you. Belt loose or flapping, there's an electrical connection that opens and turns the light on. Pull the wire and that same circuit is opened and, miracle!!!, the light comes on. Stop the flapping by adding oil to the tensioner. Verify the correct assembly of the tensioner and the spring and contacts in the switch. When you get the belt on and the tension set, but before you button all the covers on, test the tesnion monitoring circuit with an ohm meter. If you have an open circuit to ground from the pigtail, the switch is not assembled correctly. If it's closed to ground it's OK to assemble, and you know it's working. All before the covers go on, imagine that.
03-11-2010, 04:52 PM
#36
Rennlist Member
My experience with the Conti belt:
I replaced a "Porsche Timing Belt" with a Conti in 2006 after the warning light came on while decelerating from high RPM in second gear. After belt replacement and the initial re-tension after 1500 miles, I have not had to adjust my current T-belt since (I've checked it twice, both times before heading out to Shark's in the Mountans). The conti-belt was thinner than the Porsche belt I took off, which was 7 years old when I bought the car according to the records from the PO. I posted about this back in 2006. From what I recall on the post, I was asking about the thinner belt at that time. What I noticed was less "cover" over the woven interior part of the belt, mainly on the back side.
I replaced a "Porsche Timing Belt" with a Conti in 2006 after the warning light came on while decelerating from high RPM in second gear. After belt replacement and the initial re-tension after 1500 miles, I have not had to adjust my current T-belt since (I've checked it twice, both times before heading out to Shark's in the Mountans). The conti-belt was thinner than the Porsche belt I took off, which was 7 years old when I bought the car according to the records from the PO. I posted about this back in 2006. From what I recall on the post, I was asking about the thinner belt at that time. What I noticed was less "cover" over the woven interior part of the belt, mainly on the back side.
03-15-2010, 04:12 PM
#39
Vegas, Baby!
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I don't know if this is relevant or not. I've run belt drives on all my Harley road bikes scence Dick Allen invented them in the late sixties. In the early days we had square toothed belts like the blower belts on top fuel rails. We used to call then junk drives, the belts would come flying off if the tranny and engine wern't perfectly lined up. Also in the early days all belt drives were open primaries. As the belt technology improved they went from square teeth to rounded. Pacific Broach made all my custom, engine pulleys, clutch hubs, countershaft pulleys, and drive pulleys. The major reason for engine to transmission belt drive failures, were due to heat and detergent oil on the belt, when we went to enclosed primaries. As anyone that ownes a later model harley will tell you the final drive belts never fail. When Harley went from dry to wet clutches, Primo, and Phase III recomended using thier own brands of non-detergent oil for use in the primary cases. I'am from the old school, and still run dry clutches in my scooters.
I don't know if it would be a factor of belt failure, but would using detergent oil in the tensioner be a cause of belt failure? Gates makes the belts for Harley belt drives. And they advise that detergent oils will affect the service life of the belts. Also I've had to have the inner and outer primary cover slotted to vent the heat. Otherwise the belts would shread within 12 to 15 thousand miles.
I don't know if it would be a factor of belt failure, but would using detergent oil in the tensioner be a cause of belt failure? Gates makes the belts for Harley belt drives. And they advise that detergent oils will affect the service life of the belts. Also I've had to have the inner and outer primary cover slotted to vent the heat. Otherwise the belts would shread within 12 to 15 thousand miles.
