lsd assembly
Chronic Tool Dropper
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Aryan
I think as a minimum when you have it on the bench in front of it's worth taking the LSD apart, cleaning every component and inspecting for wear, replacing plates as necessary, lubricating every part and re-assembling ... then doing a torque test.
I got lucky with a secondhand LSD and it didn't have significant wear, which I found after I went through the dismantle, clean, lubricate, re-assemble and test process. If you don't know the condition of parts inside it doesn't make sense to just put it in the case. It could be totally worn out, or have debris in it which could trash bearings or gears.
I think as a minimum when you have it on the bench in front of it's worth taking the LSD apart, cleaning every component and inspecting for wear, replacing plates as necessary, lubricating every part and re-assembling ... then doing a torque test.
I got lucky with a secondhand LSD and it didn't have significant wear, which I found after I went through the dismantle, clean, lubricate, re-assemble and test process. If you don't know the condition of parts inside it doesn't make sense to just put it in the case. It could be totally worn out, or have debris in it which could trash bearings or gears.
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From: Helsinki, Finland
It is. Some repairs simply should be done correctly. No matter that it costs time, money or both. There are people in here who try to cur corners. For example Kibort will possibly have to take his last 5sp gearbox installation down to go through it thoroughly sooner than he would like since he didn't do it first time around. Wanting to go to races is good excuse but it can bite back in the end. Adjusting diff shims can do also. Maybe bearings make more noice than they should or wear much more quickly. Doing adjustment factory way will pretty much guarantee diff will last as long as it possibly can. Doing things any other way can introduce uncertainty.
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Ok thanks.
Hi Dave,
I agree and besides it is fun to take things apart and put them back together again
I did dismantle, clean, inspect and measure my LSD and found .2 mm wear but torque test was in range (24 Nm where spec is 10-35 Nm).
Aryan
I think as a minimum when you have it on the bench in front of it's worth taking the LSD apart, cleaning every component and inspecting for wear, replacing plates as necessary, lubricating every part and re-assembling ... then doing a torque test.
I got lucky with a secondhand LSD and it didn't have significant wear, which I found after I went through the dismantle, clean, lubricate, re-assemble and test process. If you don't know the condition of parts inside it doesn't make sense to just put it in the case. It could be totally worn out, or have debris in it which could trash bearings or gears.
I think as a minimum when you have it on the bench in front of it's worth taking the LSD apart, cleaning every component and inspecting for wear, replacing plates as necessary, lubricating every part and re-assembling ... then doing a torque test.
I got lucky with a secondhand LSD and it didn't have significant wear, which I found after I went through the dismantle, clean, lubricate, re-assemble and test process. If you don't know the condition of parts inside it doesn't make sense to just put it in the case. It could be totally worn out, or have debris in it which could trash bearings or gears.
I agree and besides it is fun to take things apart and put them back together again
I did dismantle, clean, inspect and measure my LSD and found .2 mm wear but torque test was in range (24 Nm where spec is 10-35 Nm).
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From: Tasmania, Australia
I figure if you aim for perfection you won't always achieve it, but you'll at least come close ... and if you think near enough is good enough, you'll end up with a pile of crap everytime.
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Oh give me a break - there is more than one way to get a correct answer. If you do not understand the principles involved then you will never understand what you are doing. There are far too many mechanics out there who cannot look at parts and determine which are good and which are bad - so they cost the customer more and do not necessarily do as good a job.
Back when I was rebuilding VW engines it was thought that you could not re-ring a VW engine. We did it all the time using used pistons that were select fit to honed barrels from a big pile of cylinders. Never once lost an engine out of the over 1000 we rebuilt. This gave us a strategic advantage over the competiion who were using new sets from Brazil that had high failure rates. The same was true for cams and lifters. We were the only ones in town oftering a 2 year or 24K mile gurantee. It is all about knowing what the specs are and what will work. I also commited sacralige by doing valve jobs on VW engines - never lost a bottom end as a result. Myths are myths and knowledge is the antiddote.
Ok the concept on the diff is easy. One starts with the assumption the pinion is set right since the rest of the box has not been apart. Besides measuring pinion depth is pretty easy to set. As a side note the shims are more related to the difference in the cases than the ring and pinion and carrier. The machining on the case is by far the biggest variable. You can get away with changing bearings and using the same shims in most cases.
The carrier in the case is suppose to have zero lash. This means there is no end play. The factory way is to remove the ring and get the total size of the shims to get zero lash. But that method will not get you the left side shims. Putting the carrier in with the ring and mating it to the pinion measuring the back lash will set the ring in relation to the pinion. Using bluing is also helpful. A used ring and pinion will have wear marks that are easy to check with some bluing. All you can do no matter what method you use is the measure the number of shims on the left side. This method will get that number
Putting the right cover on without shims allows one to get zero lash. As one tightens the cover it is easy to find that point. Ok at that point you have backlash set correctly and zero lash. All that is left to do is to measure the space between the right cover and the case. This is the right cover shim amount.
Experience in rebuilding over 200 VW transaxles (which is a more difficult job than the Porsche transmission) has showed me that in 99.9% of the cases shims that are with the case are the shims needed to set up any ring and pinion. The ring and pinion gears and carrier are machined to much higher tolerances than the cases.
Besides the only thing you have to adjust is the side covers. There is no extra magic tweeks here. And for the record I have never had a ring and pinion set up howl or fail prematurely.
Back when I was rebuilding VW engines it was thought that you could not re-ring a VW engine. We did it all the time using used pistons that were select fit to honed barrels from a big pile of cylinders. Never once lost an engine out of the over 1000 we rebuilt. This gave us a strategic advantage over the competiion who were using new sets from Brazil that had high failure rates. The same was true for cams and lifters. We were the only ones in town oftering a 2 year or 24K mile gurantee. It is all about knowing what the specs are and what will work. I also commited sacralige by doing valve jobs on VW engines - never lost a bottom end as a result. Myths are myths and knowledge is the antiddote.
Ok the concept on the diff is easy. One starts with the assumption the pinion is set right since the rest of the box has not been apart. Besides measuring pinion depth is pretty easy to set. As a side note the shims are more related to the difference in the cases than the ring and pinion and carrier. The machining on the case is by far the biggest variable. You can get away with changing bearings and using the same shims in most cases.
The carrier in the case is suppose to have zero lash. This means there is no end play. The factory way is to remove the ring and get the total size of the shims to get zero lash. But that method will not get you the left side shims. Putting the carrier in with the ring and mating it to the pinion measuring the back lash will set the ring in relation to the pinion. Using bluing is also helpful. A used ring and pinion will have wear marks that are easy to check with some bluing. All you can do no matter what method you use is the measure the number of shims on the left side. This method will get that number
Putting the right cover on without shims allows one to get zero lash. As one tightens the cover it is easy to find that point. Ok at that point you have backlash set correctly and zero lash. All that is left to do is to measure the space between the right cover and the case. This is the right cover shim amount.
Experience in rebuilding over 200 VW transaxles (which is a more difficult job than the Porsche transmission) has showed me that in 99.9% of the cases shims that are with the case are the shims needed to set up any ring and pinion. The ring and pinion gears and carrier are machined to much higher tolerances than the cases.
Besides the only thing you have to adjust is the side covers. There is no extra magic tweeks here. And for the record I have never had a ring and pinion set up howl or fail prematurely.
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I agree that S1 and S2 shim selection done in factory way is too complex and can be done easier ring in place by mounting right side cover without shims and checking S1+S2 distance from the left side. But that still leaves S3 which I believe was not checked at all even though pinion was changed. Thats mistake in my mind.
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My comments in blue:
Oh give me a break - there is more than one way to get a correct answer. If you do not understand the principles involved then you will never understand what you are doing.
That's why someone doing a rebuild for the first time should be directed to follow the tried and true WSM method ... it works and is set out in words and pictures.
There are far too many mechanics out there who cannot look at parts and determine which are good and which are bad - so they cost the customer more and do not necessarily do as good a job.
I understand the principles, and yes I acknowledge that sometimes there are better ways to do things, which is what this forum is about. In this instance, however, you've advocated a different method which will not necessarily replicate the original setup, or correct bearing preload and crown wheel/pinion backlash.
Back when I was rebuilding VW engines it was thought that you could not re-ring a VW engine. We did it all the time using used pistons that were select fit to honed barrels from a big pile of cylinders. Never once lost an engine out of the over 1000 we rebuilt. This gave us a strategic advantage over the competiion who were using new sets from Brazil that had high failure rates. The same was true for cams and lifters. We were the only ones in town oftering a 2 year or 24K mile gurantee. It is all about knowing what the specs are and what will work. I also commited sacralige by doing valve jobs on VW engines - never lost a bottom end as a result. Myths are myths and knowledge is the antiddote.
Ok the concept on the diff is easy. One starts with the assumption the pinion is set right since the rest of the box has not been apart. Besides measuring pinion depth is pretty easy to set. As a side note the shims are more related to the difference in the cases than the ring and pinion and carrier.
Not necessarily ... maybe one ... maybe the other ... maybe a combination of the two.
The machining on the case is by far the biggest variable. You can get away with changing bearings and using the same shims in most cases.
But you're assuming that the new bearings and LSD carrier are dimensionally identical to the old bearings and carrier ... big call without doing any measurements. The bottom line is that you need to replicate the bearing preload, and the crown wheel and pinion backlash, and you can only do that by measurement.
The carrier in the case is suppose to have zero lash. This means there is no end play.
The WSM calls for 0.30mm bearing preload (crush).
The factory way is to remove the ring and get the total size of the shims to get zero lash. But that method will not get you the left side shims. Putting the carrier in with the ring and mating it to the pinion measuring the back lash will set the ring in relation to the pinion. Using bluing is also helpful. A used ring and pinion will have wear marks that are easy to check with some bluing. All you can do no matter what method you use is the measure the number of shims on the left side. This method will get that number
Shims are available in 0.10mm, 0.15mm, 0.20mm, 0.25mm and 0.30mm. Shimming is not by the number of shims, it's by the thickness of shims and the number and combination to give the total measurement required.
Putting the right cover on without shims allows one to get zero lash. As one tightens the cover it is easy to find that point. Ok at that point you have backlash set correctly and zero lash. All that is left to do is to measure the space between the right cover and the case. This is the right cover shim amount.
Backlash for the crown wheel and pinion set is stamped on the crown wheel, is not zero, and varies according to the measurement the factory determined as the best silent run position.
Experience in rebuilding over 200 VW transaxles (which is a more difficult job than the Porsche transmission) has showed me that in 99.9% of the cases shims that are with the case are the shims needed to set up any ring and pinion. The ring and pinion gears and carrier are machined to much higher tolerances than the cases.
Besides the only thing you have to adjust is the side covers. There is no extra magic tweeks here. And for the record I have never had a ring and pinion set up howl or fail prematurely.
What you've set out is not clear in relation to the terms you're using (nowhere do you mention preload - just lash), or the precise sequence you're suggesting, and is contrary to the WSM procedure in any case.
That's why someone doing a rebuild for the first time should be directed to follow the tried and true WSM method ... it works and is set out in words and pictures.
There are far too many mechanics out there who cannot look at parts and determine which are good and which are bad - so they cost the customer more and do not necessarily do as good a job.
I understand the principles, and yes I acknowledge that sometimes there are better ways to do things, which is what this forum is about. In this instance, however, you've advocated a different method which will not necessarily replicate the original setup, or correct bearing preload and crown wheel/pinion backlash.
Back when I was rebuilding VW engines it was thought that you could not re-ring a VW engine. We did it all the time using used pistons that were select fit to honed barrels from a big pile of cylinders. Never once lost an engine out of the over 1000 we rebuilt. This gave us a strategic advantage over the competiion who were using new sets from Brazil that had high failure rates. The same was true for cams and lifters. We were the only ones in town oftering a 2 year or 24K mile gurantee. It is all about knowing what the specs are and what will work. I also commited sacralige by doing valve jobs on VW engines - never lost a bottom end as a result. Myths are myths and knowledge is the antiddote.
Ok the concept on the diff is easy. One starts with the assumption the pinion is set right since the rest of the box has not been apart. Besides measuring pinion depth is pretty easy to set. As a side note the shims are more related to the difference in the cases than the ring and pinion and carrier.
Not necessarily ... maybe one ... maybe the other ... maybe a combination of the two.
The machining on the case is by far the biggest variable. You can get away with changing bearings and using the same shims in most cases.
But you're assuming that the new bearings and LSD carrier are dimensionally identical to the old bearings and carrier ... big call without doing any measurements. The bottom line is that you need to replicate the bearing preload, and the crown wheel and pinion backlash, and you can only do that by measurement.
The carrier in the case is suppose to have zero lash. This means there is no end play.
The WSM calls for 0.30mm bearing preload (crush).
The factory way is to remove the ring and get the total size of the shims to get zero lash. But that method will not get you the left side shims. Putting the carrier in with the ring and mating it to the pinion measuring the back lash will set the ring in relation to the pinion. Using bluing is also helpful. A used ring and pinion will have wear marks that are easy to check with some bluing. All you can do no matter what method you use is the measure the number of shims on the left side. This method will get that number
Shims are available in 0.10mm, 0.15mm, 0.20mm, 0.25mm and 0.30mm. Shimming is not by the number of shims, it's by the thickness of shims and the number and combination to give the total measurement required.
Putting the right cover on without shims allows one to get zero lash. As one tightens the cover it is easy to find that point. Ok at that point you have backlash set correctly and zero lash. All that is left to do is to measure the space between the right cover and the case. This is the right cover shim amount.
Backlash for the crown wheel and pinion set is stamped on the crown wheel, is not zero, and varies according to the measurement the factory determined as the best silent run position.
Experience in rebuilding over 200 VW transaxles (which is a more difficult job than the Porsche transmission) has showed me that in 99.9% of the cases shims that are with the case are the shims needed to set up any ring and pinion. The ring and pinion gears and carrier are machined to much higher tolerances than the cases.
Besides the only thing you have to adjust is the side covers. There is no extra magic tweeks here. And for the record I have never had a ring and pinion set up howl or fail prematurely.
What you've set out is not clear in relation to the terms you're using (nowhere do you mention preload - just lash), or the precise sequence you're suggesting, and is contrary to the WSM procedure in any case.
