Torque tube bushing differences /pics of rubbing driveshaft couplers / vibration test
03-13-2008, 08:27 AM
#21
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SpeedyD ....good thought process......sounds like you understand what is happening very well.....when I talk to people they dont understand the mechanics of the setup and the findings.
Here are some issues that may flaw your theory.
1. Both the front and rear bushings are rubbing in the exact 3 places on each. If it were an alignment problem I wouldnt expect it to rub in 3 distinct areas on both the front and rear couplers. also I took the drivehshaft...unhooked the front and bent the shaft 10 inches to see how the coupler would change....but there was no expansion..just some "krinkle"...definately 1/4 of circumfrential expansion. The rubbing occured all the way around the tube ...unlikely in an alignment issue.
I also ran the coupler on a bench motor with a dial indicator...no expansion at 3000rpm.
I DO think the problem is occuring in the converter or converter alignment...causing the converter to wobble. I think the rubber coupler issue is secondary...but very unusual and definately not right..
Thanks Tom
Here are some issues that may flaw your theory.
1. Both the front and rear bushings are rubbing in the exact 3 places on each. If it were an alignment problem I wouldnt expect it to rub in 3 distinct areas on both the front and rear couplers. also I took the drivehshaft...unhooked the front and bent the shaft 10 inches to see how the coupler would change....but there was no expansion..just some "krinkle"...definately 1/4 of circumfrential expansion. The rubbing occured all the way around the tube ...unlikely in an alignment issue.
I also ran the coupler on a bench motor with a dial indicator...no expansion at 3000rpm.
I DO think the problem is occuring in the converter or converter alignment...causing the converter to wobble. I think the rubber coupler issue is secondary...but very unusual and definately not right..
Thanks Tom
06-09-2008, 11:54 PM
#22
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Just wanted to add to this that I will be installing the m3, m5 etc guibo on mine. Got them today and they appear to be a much harder rubber. Much like the polyurethane as you descibed your GM ones to be. They ran $160 for the pair.
These are for the 12mm applications. Going in end of next week.
link to my thread I have going :http://forums.corvetteforum.com/show....php?t=2043749
brett
These are for the 12mm applications. Going in end of next week.
link to my thread I have going :http://forums.corvetteforum.com/show....php?t=2043749
brett
10-31-2008, 05:55 PM
#23
I was one of those people who actually compared the two couplers and posted pics and info showing that they were interchagable. I went ahead and installed them on my 98 a4 c5 and the car ran super smooth for about 5k-7k miles. keep in mind I am one of those aggresive drivers where my tranny goes every 30k miles more or less. These bmw couplers have been in there 20k miles now and i feel the vibration coming back. My personal decesion to use them was the fact i could not find the harder vette couplers. it was not the fact i wanted to save money. where are you guys getting the harder vette couplers? I use the 10mm (which is what the bmw 318 uses) not the 12mm application .
today i just ordered two solid couplers from LG ...thye say there will be absolutly no vibration with two solid couplers. The only problem is a whine which really does not bother me. He says the whine is much like a stick shift when you install a short throw shifter. That comment didnt make much sense to me since i have always had automatics, but i'll take a while over these soft couplers that dont hold up to te abuse..
By the way if your couplers are rubbing on the inside of the tube dont worry my old ones did the same thing. Once you install new ones it goes away and it runs smooth. . what you have to figure is that these things get twisted under load and cause it to distort causing the rubbing. did you check if your torque converter is properly balanced. some times torque converters internal fins break off and causes them to be out of balance.
that my take on things ...by the way very impressive that you got enginners to test this stuff!
Best,
Rafael
today i just ordered two solid couplers from LG ...thye say there will be absolutly no vibration with two solid couplers. The only problem is a whine which really does not bother me. He says the whine is much like a stick shift when you install a short throw shifter. That comment didnt make much sense to me since i have always had automatics, but i'll take a while over these soft couplers that dont hold up to te abuse..
By the way if your couplers are rubbing on the inside of the tube dont worry my old ones did the same thing. Once you install new ones it goes away and it runs smooth. . what you have to figure is that these things get twisted under load and cause it to distort causing the rubbing. did you check if your torque converter is properly balanced. some times torque converters internal fins break off and causes them to be out of balance.
that my take on things ...by the way very impressive that you got enginners to test this stuff!
Best,
Rafael
In my opinion they are not as strong. I have had 3 engineers at Pratt and Whitney (design and test jet engines / one of them balances 6 foot turbine shafts that run 60,000rpm) run some tests on them. Hardness of the rubber is close to 1/2 of what the GM units are. We also ran som flexability tests on the couplers to check for the possiblity expansion. It took 2x the pressure to move the couple out of plane .250". This is directly related to the hardness of the rubber.
These 2 tests alone show that the potential of movement / flex is greater with the BMW pieces. This in turn could lead to premature failure.
As far as my setup...the driveshaft / couplers / shafts ..etc , etc are all the same as what everyone else is using. These were my findings. I didnt just slap things together and make a statement when I had a problem..
I am very mechanically enclined and usually test items when I have a problem.......anyone else on this forum ever jig up a fixture to run the driveshaft open so that measurement can be taken throughout the RPM range? Anyone else ever had the couplers check by engineers?
I know my setup is different in other aspects.......if people want to save a few bucks to run the BMW couplers......thats fine! But I think everyone is entilted to hear and see what I found. The forum is to post information that can help people avoid mistakes in the future....
I wish I had known about this before I purchased the BMW units...
I understand there are businesses selling these....I am not here to hurt businesses...............but people have a right to know what my findings are!
I can tell you that I have been screwed over and over again and wasted alot of money by businesses telling me wrong information just to get a sale.....with no testing or info to back it!
Guys .....I am posting what I find......keep the posts coming.......USEFUL posts are appreciated......
I am very frustrated after spending close to 15,000 on this conversion and am asking for people to post info that may be helpful.....any take away any info they feel may be helpful
Thanks Tom
These 2 tests alone show that the potential of movement / flex is greater with the BMW pieces. This in turn could lead to premature failure.
As far as my setup...the driveshaft / couplers / shafts ..etc , etc are all the same as what everyone else is using. These were my findings. I didnt just slap things together and make a statement when I had a problem..
I am very mechanically enclined and usually test items when I have a problem.......anyone else on this forum ever jig up a fixture to run the driveshaft open so that measurement can be taken throughout the RPM range? Anyone else ever had the couplers check by engineers?
I know my setup is different in other aspects.......if people want to save a few bucks to run the BMW couplers......thats fine! But I think everyone is entilted to hear and see what I found. The forum is to post information that can help people avoid mistakes in the future....
I wish I had known about this before I purchased the BMW units...
I understand there are businesses selling these....I am not here to hurt businesses...............but people have a right to know what my findings are!
I can tell you that I have been screwed over and over again and wasted alot of money by businesses telling me wrong information just to get a sale.....with no testing or info to back it!
Guys .....I am posting what I find......keep the posts coming.......USEFUL posts are appreciated......
I am very frustrated after spending close to 15,000 on this conversion and am asking for people to post info that may be helpful.....any take away any info they feel may be helpful
Thanks Tom
Last edited by Rconce01; 11-03-2008 at 12:11 PM.
01-04-2009, 03:42 PM
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St. Jude Donor '07-'08-'09-'10-'11-'12'-'13-'14-'15
Interesting. I have to keep up with this as I might have damaged my TT bushings at the track a few weeks back. I am tearing it down to see what the issue is now. Where is the best place to get solid couplers for and M6 car? What is the benefit?
Cajun
Cajun
01-04-2009, 07:59 PM
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St. Jude Donor '06 & '12
I was speaking to a well known supporting vendor who sell trannys on this forum about 3 weeks ago
. I asked the SPECIFIC question as to wether or not the couplers were the same. I specifically asked about the C5/C6, BMW 318, and larger BMW couplers. According to them, a while back they were inquiring and got ahold of the actual manufacturer (not in this country) who makes ALL of the oem couplers, for the different manufacturers.
According to the manufacturer, they use EXACTLY the same material, and same build process. There is absolutely NOTHING different in the materials used.
The only difference is the 10mm/12mm bushings, and one has a slightly different mold design. But that is all.
But (according to the manufacturer) there is ZERO difference in ANY of the the couplers themselves. Structural integrity is exactly the same.
. I asked the SPECIFIC question as to wether or not the couplers were the same. I specifically asked about the C5/C6, BMW 318, and larger BMW couplers. According to them, a while back they were inquiring and got ahold of the actual manufacturer (not in this country) who makes ALL of the oem couplers, for the different manufacturers.According to the manufacturer, they use EXACTLY the same material, and same build process. There is absolutely NOTHING different in the materials used.
The only difference is the 10mm/12mm bushings, and one has a slightly different mold design. But that is all.
But (according to the manufacturer) there is ZERO difference in ANY of the the couplers themselves. Structural integrity is exactly the same.
01-05-2009, 09:55 AM
#26
Lg motorsports makes them solid. The benefit is that once you put solid ones it will never ever break twist or vibrate... something gm should have done in the first place....If you need further advice on doing it pm me and i can give you a call.
01-05-2009, 10:19 AM
#27
Melting Slicks
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Tom. Do they usually eliminate the outter torque tube housing in this conversion ? I notice in the picture you only have the inner shaft.
Also, why bother with those rubber pieces ? I ran solid alluminium pieces with a chrome moly shaft and had no vibration or noise.
Also, why bother with those rubber pieces ? I ran solid alluminium pieces with a chrome moly shaft and had no vibration or noise.
01-05-2009, 10:44 AM
#28
the pic might show it without the exterior tube because he was checking for run off . The tube is there to protect the driver and passemger. If that drive shaft comes loose at 6,000 rpms it can really hurt someone in the car. The tube also adds alot of rigidity to the drivetrain under high load conditions where the entire car tends to flex.
thats just my opinion lets see what Tom says.
thats just my opinion lets see what Tom says.
01-05-2009, 10:46 AM
#29
Melting Slicks
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I would like to see more pictures of the drive line installed. Is it possible you may not have clearanced the tunnel enough and the trans or bell housing may be touching ? Have you thought of solid mounts for the motor ?
01-05-2009, 01:46 PM
#30
Melting Slicks
There's no reason to fool with rubber crap ever again. Also, the way the car lopes and rumbles I can't notice if vibration increased or not so no big deal.
Last edited by Drewstein; 01-05-2009 at 01:50 PM.
01-09-2009, 11:27 PM
#31
Le Mans Master
Are you running solid ones front and rear? And do you have the stock TT that came in your 99, or did you upgrade to the later style?
01-10-2009, 02:41 AM
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St. Jude Donor '06 & '12
This was actually an old thread.
It turned out that it wasn't his couplers at all. If memory serves me right, it was either his driveshaft being out of balance, or the shaft was bent...But it wasn't the couplers at all..(to the best of my knowledge that is)
It turned out that it wasn't his couplers at all. If memory serves me right, it was either his driveshaft being out of balance, or the shaft was bent...But it wasn't the couplers at all..(to the best of my knowledge that is)
01-10-2009, 10:28 AM
#33
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St. Jude Donor '07-'08-'09-'10-'11-'12'-'13-'14-'15
I have a buddy who can machine me some billet torque tube couplers but I need the dimensions. Does anyone know what an 99 M6 couple coupler measures? Should I replace both or just one? Are the front and rear the same size? Thanks
Cajun
Cajun
01-19-2009, 04:34 PM
#34
Heel & Toe
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I need help! This is the first time I have owned a Corvette. Have a '98, 6 speed with 54K. It has started to chunk/chatter when you engage the clutch from a standing start (forward or reverse). It is fine once it is moving. If you find the exact RPM you can eliminate the hic-up start. Most times it is just embarassing, like your first clutch. I assume PP and disc but have people telling me it could be TT bushings. How will I know? Is it an obvious thing when I get it torn down? Also, does the clutch slave normally give out to the point I should just replace it? Money isn't my strong point so I am trying to do as little as possible.
01-19-2009, 05:12 PM
#35
I need help! This is the first time I have owned a Corvette. Have a '98, 6 speed with 54K. It has started to chunk/chatter when you engage the clutch from a standing start (forward or reverse). It is fine once it is moving. If you find the exact RPM you can eliminate the hic-up start. Most times it is just embarassing, like your first clutch. I assume PP and disc but have people telling me it could be TT bushings. How will I know? Is it an obvious thing when I get it torn down? Also, does the clutch slave normally give out to the point I should just replace it? Money isn't my strong point so I am trying to do as little as possible.
sorry to hear that, well if your bushings are bad you will knowthe following way.
1. engage the clutch (pedal off the clutch to the torque tube spins) with the car in neutral and rev it up through the entire rpm range 1.000 2,000 3,000 4,000 5,000 . if it vibrates you have a bad torque tube bushings or a bad pilot bearing bushing. If the car is perfectly smooth then its a bad pressure plate( perhaps it is warped due to overheating) or you may have a bad clutch.
Its very hard to damage torque tube bushings in 50k miles (under normal driving conditions)
I personally damaged mine twice at intervals of 20k miles until i went with the solid aluminum bushing setup.
Good luck and keep us posted on progress
Ralph
01-19-2009, 06:00 PM
#36
Melting Slicks
Simple fix that could have saved me thousands.
01-19-2009, 07:31 PM
#37
Heel & Toe
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sorry to hear that, well if your bushings are bad you will knowthe following way.
1. engage the clutch (pedal off the clutch to the torque tube spins) with the car in neutral and rev it up through the entire rpm range 1.000 2,000 3,000 4,000 5,000 . if it vibrates you have a bad torque tube bushings or a bad pilot bearing bushing. If the car is perfectly smooth then its a bad pressure plate( perhaps it is warped due to overheating) or you may have a bad clutch.
Its very hard to damage torque tube bushings in 50k miles (under normal driving conditions)
I personally damaged mine twice at intervals of 20k miles until i went with the solid aluminum bushing setup.
Good luck and keep us posted on progress
Ralph
1. engage the clutch (pedal off the clutch to the torque tube spins) with the car in neutral and rev it up through the entire rpm range 1.000 2,000 3,000 4,000 5,000 . if it vibrates you have a bad torque tube bushings or a bad pilot bearing bushing. If the car is perfectly smooth then its a bad pressure plate( perhaps it is warped due to overheating) or you may have a bad clutch.
Its very hard to damage torque tube bushings in 50k miles (under normal driving conditions)
I personally damaged mine twice at intervals of 20k miles until i went with the solid aluminum bushing setup.
Good luck and keep us posted on progress
Ralph
01-20-2009, 02:16 PM
#38
tt
Thanks for the prompt reply. You are the first to give me some type of actual test. Everyone else just keeps saying it might be this and might be that--just replace everything. I have a problem. The car is on stands and the exhaust is off--I started the clutch replacement while the car is up for the winter. I am not so far that I can't put the exhaust back on to do the check. Can I inspect visually when I get the TT separated? This is my first experience with a Corvette tear down. I am the 3rd owner. The guy I bought it from owned a suspension shop and used it to autocross as advertisement. I am easy on street cars but I assume he used up the clutch at track day.
Although your torque tube is probably fine any signs of rubber debris when you pull the backing plate off your torque tube assembly will indicate you bushings are starting to fail. The rear one always fails quicker than the front one. I can really help you out as far as disassembly and complete testing and rebuilding of the torque tube. I don't know anything about clutch assemblies ( I am an automatic type of guy) All i know is that many people here that have had issues with there clutch sometimes do not fix it on the first shot. Just like torque converters on automatics you need to make sure your clutch is properly balanced and that everything is properly centered to ensure a trouble free result.
I had an idiot sell me a out of balanced torque converter and the amount of work and frustration that it caused me was unimaginable.
drop me a PM if you want pics of the process and or advice.
Best of Luck!
01-20-2009, 03:30 PM
#39
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well you can do the test with the exhaust off or on it really doesn't matter. Well it might matter to the neighbors but as far as a testing procedure for vibrations with the exahust on or off does not make any difference. I can almost bet your problem is within the clutch / pressure plate assemblies. Yes you can visually inspect the torque tube for coupler damage and no you shouldn't buy a new torque tube if you rubber bushings are bad. There are many solutions to rebuild your torque tube. The #1 failure is the stock rubber bushings which give out around 100k miles. If your a normal driver you can buy this busings at a BMW dealership very cheap(80 bucks per bushing) If your an aggressive driver and really squeeze the heck outta your vette the busings that are solid aluminum are you best bet. #2 failure is the bearings in the torque tube (these last a while i am over 150k miles on the stock ones) #3 failure is a bent shaft mostly due to bushing failure.
Although your torque tube is probably fine any signs of rubber debris when you pull the backing plate off your torque tube assembly will indicate you bushings are starting to fail. The rear one always fails quicker than the front one. I can really help you out as far as disassembly and complete testing and rebuilding of the torque tube. I don't know anything about clutch assemblies ( I am an automatic type of guy) All i know is that many people here that have had issues with there clutch sometimes do not fix it on the first shot. Just like torque converters on automatics you need to make sure your clutch is properly balanced and that everything is properly centered to ensure a trouble free result.
I had an idiot sell me a out of balanced torque converter and the amount of work and frustration that it caused me was unimaginable.
drop me a PM if you want pics of the process and or advice.
Best of Luck!
Although your torque tube is probably fine any signs of rubber debris when you pull the backing plate off your torque tube assembly will indicate you bushings are starting to fail. The rear one always fails quicker than the front one. I can really help you out as far as disassembly and complete testing and rebuilding of the torque tube. I don't know anything about clutch assemblies ( I am an automatic type of guy) All i know is that many people here that have had issues with there clutch sometimes do not fix it on the first shot. Just like torque converters on automatics you need to make sure your clutch is properly balanced and that everything is properly centered to ensure a trouble free result.
I had an idiot sell me a out of balanced torque converter and the amount of work and frustration that it caused me was unimaginable.
drop me a PM if you want pics of the process and or advice.
Best of Luck!
01-20-2009, 08:14 PM
#40
Burning Brakes
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just some food for thought, we just pulled my car apart because it was clunking pretty bad at idle, and found that the rear bushing was completely gone. I hope my drive shaft is straight still!
I order my bushings from corvette central for about $70 for the both of em. I called RPM and they told me that there was no difference in the bushings and that they were all made at the same place. I wasn't able to find those harder GM pieces. I'm putting those GM ones in, and we'll see how it goes. I didn't go with the billet ones because of fear of vibrations. I'll try to post pictures of the destroyed piece when we get back to working on the car. Its snowing in North Carolina LOL!
I order my bushings from corvette central for about $70 for the both of em. I called RPM and they told me that there was no difference in the bushings and that they were all made at the same place. I wasn't able to find those harder GM pieces. I'm putting those GM ones in, and we'll see how it goes. I didn't go with the billet ones because of fear of vibrations. I'll try to post pictures of the destroyed piece when we get back to working on the car. Its snowing in North Carolina LOL!