Bruce and Sean Buchanan @ Buchanan Automotive on oil, TT, and TBF
02-05-2023, 10:42 PM
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Bruce and Sean Buchanan @ Buchanan Automotive on oil, TT, and TBF
The post he references in this video probably came from this thread - @JET951
https://rennlist.com/forums/928-foru...xperience.html
https://rennlist.com/forums/928-foru...xperience.html
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Popular Reply
02-08-2023, 05:30 PM
Drifting
Hi TV , the below is a post I put on Rennlist on the 05-14-2015 , the Title of the thread was = Flexplate Question & I was responding to John C ( post 2 ) }
As John C has mentioned , its mainly the rear coupling index bolt that looses its tension over time ( the bolt does not loosen it stretches with acceleration events over time & because the Auto trans version, the rear coupling inspection hole is well covered with heat shields ( out of sight & out of mind ) and so over time no one checks whats going on in there ( meaning is the single index bolt still tight ? )
For the last few decades we simply ( on major services ) just check & if needed reset the position of the T Tube shaft & always fit new index bolts ( F & R ) , grease the threads of these bolts ( do not loctite them ) because if you loctite them you will go back to check their tension / torque say 20,000 kms later only to find they are tight , but its the threads that are tight( because of the loctite) not the bolt head to coupling
And of course we always reset the TT shaft( centralise) if the said 928 TT shaft has migrated forward & they always migrate forward if the rear coupling has lost its tension because of stretch & with only one bolt , they stretch , where as the earlier 3 speed auto trans version they had two bolts on a sliding sleeve , this was an excellent design ( much stronger ) & if one looks at the last evolutionary step Porsche made ( the 968 ) the rear coupling had 4 index bolts ( YES 4 of them ) = perfection , this was the fix the 928 needed & would have received if the model continued
Just why the rear coupling index bolt stretches ( looses its tension ) much more than the front of TT coupling is a slight mystery , but I couldn't care less , it just does & its simple to maintain over decades as we have been doing
OH , in case you are wondering , do we see engine thrust bearing wear ?
Answer = NO
Why = because of us checking the above on a regular basis ( once a year or so ) = very simple , but more importantly we use high oil film strength engine oils & for our climate a min viscosity of 20w-50 & lucky for us most 20w-50 oils( last century viscosity for a last century engine ) are rich in ZDDP & engine /crankshaft thrust bearings get very little or no oil pressure at the thrust bearing surfaces ( between the two metal surfaces the bearing is = oil film strength & not the metal surfaces grinding against each other ) and you are going to struggle to get enough oil film strength with a 5w-40 this century engine oil unless you find a 5w-40 with more ZDDP than usual
I would only use a 5w-40 engine oil in a last century 928 or 944 or air cooled 911 engine if the ambient air temp did NOT rise above + 5 deg cel , meaning the average air temp is around minus 10 deg cel or below & it must be rich in ZDDP for the high loaded flat tappet overhead cams( 944 & 928 ) & thrust bearing
But what the hell would I know , I have only been working on Porsche cars since 1977 & thats only 38 years ( 46 years as of 2023 )
PS } I am getting tired of warning people of these simple things , I should stop because we make a **** load of money fixing them when people keep doing stupid **** to these cars, like using low oil film strength oils & not checking the rear coupling on a regular basis
Regards
Bruce Buchanan
Buchanan Automotive
As John C has mentioned , its mainly the rear coupling index bolt that looses its tension over time ( the bolt does not loosen it stretches with acceleration events over time & because the Auto trans version, the rear coupling inspection hole is well covered with heat shields ( out of sight & out of mind ) and so over time no one checks whats going on in there ( meaning is the single index bolt still tight ? )
For the last few decades we simply ( on major services ) just check & if needed reset the position of the T Tube shaft & always fit new index bolts ( F & R ) , grease the threads of these bolts ( do not loctite them ) because if you loctite them you will go back to check their tension / torque say 20,000 kms later only to find they are tight , but its the threads that are tight( because of the loctite) not the bolt head to coupling
And of course we always reset the TT shaft( centralise) if the said 928 TT shaft has migrated forward & they always migrate forward if the rear coupling has lost its tension because of stretch & with only one bolt , they stretch , where as the earlier 3 speed auto trans version they had two bolts on a sliding sleeve , this was an excellent design ( much stronger ) & if one looks at the last evolutionary step Porsche made ( the 968 ) the rear coupling had 4 index bolts ( YES 4 of them ) = perfection , this was the fix the 928 needed & would have received if the model continued
Just why the rear coupling index bolt stretches ( looses its tension ) much more than the front of TT coupling is a slight mystery , but I couldn't care less , it just does & its simple to maintain over decades as we have been doing
OH , in case you are wondering , do we see engine thrust bearing wear ?
Answer = NO
Why = because of us checking the above on a regular basis ( once a year or so ) = very simple , but more importantly we use high oil film strength engine oils & for our climate a min viscosity of 20w-50 & lucky for us most 20w-50 oils( last century viscosity for a last century engine ) are rich in ZDDP & engine /crankshaft thrust bearings get very little or no oil pressure at the thrust bearing surfaces ( between the two metal surfaces the bearing is = oil film strength & not the metal surfaces grinding against each other ) and you are going to struggle to get enough oil film strength with a 5w-40 this century engine oil unless you find a 5w-40 with more ZDDP than usual
I would only use a 5w-40 engine oil in a last century 928 or 944 or air cooled 911 engine if the ambient air temp did NOT rise above + 5 deg cel , meaning the average air temp is around minus 10 deg cel or below & it must be rich in ZDDP for the high loaded flat tappet overhead cams( 944 & 928 ) & thrust bearing
But what the hell would I know , I have only been working on Porsche cars since 1977 & thats only 38 years ( 46 years as of 2023 )
PS } I am getting tired of warning people of these simple things , I should stop because we make a **** load of money fixing them when people keep doing stupid **** to these cars, like using low oil film strength oils & not checking the rear coupling on a regular basis
Regards
Bruce Buchanan
Buchanan Automotive
02-06-2023, 12:49 PM
#3
Rennlist Member
These guys are Australias version of Greg Brown. Great guys.
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02-08-2023, 12:15 PM
#8
Drifting
Did we though? I knew it had 1 but other than seeing that inaccessible black hole in the early part of the vid, I still know too little.
So we remove the exhaust and shields, then what?? Hand crank the engine to expose the hole or line up the bolt?? Then what. Do we just tighten the existing bolt?? to what torque spec?? Do we replace the bolt with a new one and in doing so does the clamp fall apart into the torque tube never to be seen again.
I need to see a video doing this specific job well lit and step by step
Last edited by tv; 02-08-2023 at 02:47 PM.
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hernanca (02-09-2023)
02-08-2023, 05:30 PM
#9
Drifting
Hi TV , the below is a post I put on Rennlist on the 05-14-2015 , the Title of the thread was = Flexplate Question & I was responding to John C ( post 2 ) }
As John C has mentioned , its mainly the rear coupling index bolt that looses its tension over time ( the bolt does not loosen it stretches with acceleration events over time & because the Auto trans version, the rear coupling inspection hole is well covered with heat shields ( out of sight & out of mind ) and so over time no one checks whats going on in there ( meaning is the single index bolt still tight ? )
For the last few decades we simply ( on major services ) just check & if needed reset the position of the T Tube shaft & always fit new index bolts ( F & R ) , grease the threads of these bolts ( do not loctite them ) because if you loctite them you will go back to check their tension / torque say 20,000 kms later only to find they are tight , but its the threads that are tight( because of the loctite) not the bolt head to coupling
And of course we always reset the TT shaft( centralise) if the said 928 TT shaft has migrated forward & they always migrate forward if the rear coupling has lost its tension because of stretch & with only one bolt , they stretch , where as the earlier 3 speed auto trans version they had two bolts on a sliding sleeve , this was an excellent design ( much stronger ) & if one looks at the last evolutionary step Porsche made ( the 968 ) the rear coupling had 4 index bolts ( YES 4 of them ) = perfection , this was the fix the 928 needed & would have received if the model continued
Just why the rear coupling index bolt stretches ( looses its tension ) much more than the front of TT coupling is a slight mystery , but I couldn't care less , it just does & its simple to maintain over decades as we have been doing
OH , in case you are wondering , do we see engine thrust bearing wear ?
Answer = NO
Why = because of us checking the above on a regular basis ( once a year or so ) = very simple , but more importantly we use high oil film strength engine oils & for our climate a min viscosity of 20w-50 & lucky for us most 20w-50 oils( last century viscosity for a last century engine ) are rich in ZDDP & engine /crankshaft thrust bearings get very little or no oil pressure at the thrust bearing surfaces ( between the two metal surfaces the bearing is = oil film strength & not the metal surfaces grinding against each other ) and you are going to struggle to get enough oil film strength with a 5w-40 this century engine oil unless you find a 5w-40 with more ZDDP than usual
I would only use a 5w-40 engine oil in a last century 928 or 944 or air cooled 911 engine if the ambient air temp did NOT rise above + 5 deg cel , meaning the average air temp is around minus 10 deg cel or below & it must be rich in ZDDP for the high loaded flat tappet overhead cams( 944 & 928 ) & thrust bearing
But what the hell would I know , I have only been working on Porsche cars since 1977 & thats only 38 years ( 46 years as of 2023 )
PS } I am getting tired of warning people of these simple things , I should stop because we make a **** load of money fixing them when people keep doing stupid **** to these cars, like using low oil film strength oils & not checking the rear coupling on a regular basis
Regards
Bruce Buchanan
Buchanan Automotive
As John C has mentioned , its mainly the rear coupling index bolt that looses its tension over time ( the bolt does not loosen it stretches with acceleration events over time & because the Auto trans version, the rear coupling inspection hole is well covered with heat shields ( out of sight & out of mind ) and so over time no one checks whats going on in there ( meaning is the single index bolt still tight ? )
For the last few decades we simply ( on major services ) just check & if needed reset the position of the T Tube shaft & always fit new index bolts ( F & R ) , grease the threads of these bolts ( do not loctite them ) because if you loctite them you will go back to check their tension / torque say 20,000 kms later only to find they are tight , but its the threads that are tight( because of the loctite) not the bolt head to coupling
And of course we always reset the TT shaft( centralise) if the said 928 TT shaft has migrated forward & they always migrate forward if the rear coupling has lost its tension because of stretch & with only one bolt , they stretch , where as the earlier 3 speed auto trans version they had two bolts on a sliding sleeve , this was an excellent design ( much stronger ) & if one looks at the last evolutionary step Porsche made ( the 968 ) the rear coupling had 4 index bolts ( YES 4 of them ) = perfection , this was the fix the 928 needed & would have received if the model continued
Just why the rear coupling index bolt stretches ( looses its tension ) much more than the front of TT coupling is a slight mystery , but I couldn't care less , it just does & its simple to maintain over decades as we have been doing
OH , in case you are wondering , do we see engine thrust bearing wear ?
Answer = NO
Why = because of us checking the above on a regular basis ( once a year or so ) = very simple , but more importantly we use high oil film strength engine oils & for our climate a min viscosity of 20w-50 & lucky for us most 20w-50 oils( last century viscosity for a last century engine ) are rich in ZDDP & engine /crankshaft thrust bearings get very little or no oil pressure at the thrust bearing surfaces ( between the two metal surfaces the bearing is = oil film strength & not the metal surfaces grinding against each other ) and you are going to struggle to get enough oil film strength with a 5w-40 this century engine oil unless you find a 5w-40 with more ZDDP than usual
I would only use a 5w-40 engine oil in a last century 928 or 944 or air cooled 911 engine if the ambient air temp did NOT rise above + 5 deg cel , meaning the average air temp is around minus 10 deg cel or below & it must be rich in ZDDP for the high loaded flat tappet overhead cams( 944 & 928 ) & thrust bearing
But what the hell would I know , I have only been working on Porsche cars since 1977 & thats only 38 years ( 46 years as of 2023 )
PS } I am getting tired of warning people of these simple things , I should stop because we make a **** load of money fixing them when people keep doing stupid **** to these cars, like using low oil film strength oils & not checking the rear coupling on a regular basis
Regards
Bruce Buchanan
Buchanan Automotive
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02-09-2023, 05:44 AM
#10
Rennlist Member
I don't think the video was meant to be a full tutorial. I actually enjoyed it as I have never met Bruce however have been following his wisdom as long as I have had my 928 through our own Ausy Land sharks forum. It was good to put a face to the name. I live in a different State. I have replaced both bolts as a result. Every time I have my car up high enough off the ground I check the flex plate as its a two minute job. Just with a short straight edge. I was pretty excited to see the video as I was thinking I was going to get a reveal of which oil Bruce recommends. However not. I use Penrite 20W60 with the high Zinc. Hoping that's OK and if not Bruce may warn me off if he sees this.
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02-09-2023, 12:35 PM
#11
Drifting
Thanks for the response Bruce and as Greg says the video was not a tutorial.
I still need to know what you see when you open the "viewport" on the TT.
The problems I want answers to are can you strip the head off this bolt by re-tightening and if you remove the bolt does that mess up the clamp position or the clamp itself. Luckily my tension plate has never been under much pressure. And I did readjust the front one once.
I still need to know what you see when you open the "viewport" on the TT.
The problems I want answers to are can you strip the head off this bolt by re-tightening and if you remove the bolt does that mess up the clamp position or the clamp itself. Luckily my tension plate has never been under much pressure. And I did readjust the front one once.
02-10-2023, 07:19 PM
#12
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Hi Bruce & Sean - great video and I have added it to my web site to help enlighten as many 928 owners as possible.
__________________
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."
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02-14-2023, 03:55 PM
#15
Rennlist Member
Bruce/Sean,
Very nice video and good to be able to put some faces to the names.
Back in 1999 Porsche could not get the front clamp to hold on my 1990 S4 and after being reset it would hold for about two weeks and then a somewhat unpleasant [characteristic?] vibration would set in telling me the clam had slipped. After about 3 rounds of this I refused to accept the car back until they could come up with a solution. Porsche were adamant there was no problem with the system but upon being approached by Porsche Middle East Stuttgart came back within 20 minutes with a proposed solution- to overtorque a new pinch bolt by 10% and thus set it at 66 ft lbs- we tried this and two weeks later the vibration was back.
As a matter of interest what torque do you chaps set the pinch bolts at?
Very nice video and good to be able to put some faces to the names.
Back in 1999 Porsche could not get the front clamp to hold on my 1990 S4 and after being reset it would hold for about two weeks and then a somewhat unpleasant [characteristic?] vibration would set in telling me the clam had slipped. After about 3 rounds of this I refused to accept the car back until they could come up with a solution. Porsche were adamant there was no problem with the system but upon being approached by Porsche Middle East Stuttgart came back within 20 minutes with a proposed solution- to overtorque a new pinch bolt by 10% and thus set it at 66 ft lbs- we tried this and two weeks later the vibration was back.
As a matter of interest what torque do you chaps set the pinch bolts at?