Some questions pertaining to LSD installation. DIYers only please. No keyboard mechs!
#1
05-10-2012, 07:40 PM
Join Date: Oct 2008
Location: Portland Oregon
Posts: 1,696
Rep Power: 186 
Some questions pertaining to LSD installation. DIYers only please. No keyboard mechs!
I am researching installing an LSD into my car and really want to do the install myself. Here is my disclaimer for keyboard mechanics: I don't want to sound like a jerk, but I feel I need to be up front before people start replying. I really don't care to discuss why I don't want to pay somebody else to install it. Nor do I want replies on me "screwing up" my transmission. I have excepted the risk and am beyond that. I may sound arrogant or bitter right off, but I just have no interest in discouraging posts on things that people have either a) failed at and assume everyone else will also or b) people who have not done this, but "know it is a bad idea". I am perfectly capable of tackling this job and want the hard cold facts....
With all that aside, their are three things that must be checked/adjusted for an LSD install.
With all that aside, their are three things that must be checked/adjusted for an LSD install.
1. Bearing preload.
2. gear backlash
3. differential stub axle compatibility.
2. gear backlash
3. differential stub axle compatibility.
Bearing preload is fairly straight forward to check with the correct tool setup. Many of which can be made with relative ease. The way this is checked is with a dial type torque wrench. To do this you must have the differential installed without the ring gear or the shaft seals installed. It is a torque value that indicates the resistance for the bearing preload by itself without any other resistance factors such as seals or gear friction. So the burning question is what is the correct torque value?
Gear backlash is something that is not beyond the shadetree mechanics abilities if they are attentive to details and methodical. The question is what is the allowable backlash? I cannot find this value in the repair manual. This is most likely the same as the G50 transmissions as well or at least fairly close.
differential stub axle compatibility has been touched on vaguely in other discussions. Their has been some discussion on whether the 996TT(open diff) flanges will work with LSD setups, but none to really clear it all up. I have read that the stub axles are too long and will stick out of the transmission too far. The GT2/3(stock LSD) uses a different PN flange that is of G50 origin. Others have used the 996TT stock flange without issues. So does the flange need to be modified? Or, what flange is needed to make this work?
On another note, their have been other methods of installing LSDs without the preload and backlash measurements. One fairly common and disturbing practice is to just re-use the stock shim configuration and just putting it all back together. This is not ideal. This does not take into account the changes in differential housing sizes and can cause noisy transmissions and possible premature bearing failures. The other shortcut is on that relies on taking OEM comparitive measurements to utilize the OEM shim settings to transpose to the new LSD housing by compensating for the differences in diff housing sizes. This method is not ideal, but it gets it done with better results than just re-using the stock shim configuration.
To summarize, I would like some real input from those with experience and information on this topic. Please refrain from opinions on the subject as much as actual data and experiences with this.
#2
05-10-2012, 08:14 PM
I am going to attempt this next week I will try to do a pic diy thread.
As far as the LSD/driveshaft stub compatibility what I have been able to gather is that the Quaife/Wavetrac and Carbonetic can use the stock stubs , others GT gears /oem/GT2 and others require the gt 2 carriers , I have the P/N's if you need them along with all the other OEM P/Ns for gaskets, seals, bearings ext required for the job.
I have done diffs in several cars before and I can't imagine the backlash settings and preload setup is any different than others I have done, each Diff MFG seems to have slightly different preload and backlash settings which they will give you when you purchase a diff.
Hope this helps.
Jon
As far as the LSD/driveshaft stub compatibility what I have been able to gather is that the Quaife/Wavetrac and Carbonetic can use the stock stubs , others GT gears /oem/GT2 and others require the gt 2 carriers , I have the P/N's if you need them along with all the other OEM P/Ns for gaskets, seals, bearings ext required for the job.
I have done diffs in several cars before and I can't imagine the backlash settings and preload setup is any different than others I have done, each Diff MFG seems to have slightly different preload and backlash settings which they will give you when you purchase a diff.
Hope this helps.
Jon
#3
05-10-2012, 08:18 PM
ok.. I reused my stock stubs. no oil leaks. I needed to shorten the center bolts tho. You do not need to stress to much here on backlash as the ring gear is still centered in the one plane ''depth of pinion'' now the other plane is where the ring gear sits side to side. Here is what I did, I took a overall number from the outer bearing face to outer bearing. then I removed the ring gear and bearing that runs in the trans case leaving the shim on. now measure face of flange (where the ring gear seats) to outer face of shim. match that number on you new unit. press on bearing. now take the outer face of the bearing that rides in the trans to face of where the cover bearing sits, add the number for the bearing you need to install and compare to your overall number. the difference is the thickness of your shim. hope this helps.
#4
05-10-2012, 08:26 PM
Join Date: Oct 2008
Location: Portland Oregon
Posts: 1,696
Rep Power: 186 ok.. I reused my stock stubs. no oil leaks. I needed to shorten the center bolts tho. You do not need to stress to much here on backlash as the ring gear is still centered in the one plane ''depth of pinion'' now the other plane is where the ring gear sits side to side. Here is what I did, I took a overall number from the outer bearing face to outer bearing. then I removed the ring gear and bearing that runs in the trans case leaving the shim on. now measure face of flange (where the ring gear seats) to outer face of shim. match that number on you new unit. press on bearing. now take the outer face of the bearing that rides in the trans to face of where the cover bearing sits, add the number for the bearing you need to install and compare to your overall number. the difference is the thickness of your shim. hope this helps.
Last edited by VAGscum; 05-11-2012 at 07:20 AM.
#5
05-10-2012, 08:52 PM
I would imagine this is a great idea for those of us that have done the RWD conversion....are you going to keep the ratio the same? I am looking forward to your install 
#7
05-11-2012, 11:13 AM
Join Date: Oct 2008
Location: Portland Oregon
Posts: 1,696
Rep Power: 186
Gt3 diff with new style plates/vanes? That is $900 alone in just the plates isn't it? Or is their another cheaper and effective source? The OEM diff parts are pretty steep from what I have seen. I was pricing out a used gt2 oem LSD for $600 and when you factor in rebuilding it(because it is about 90% chance of needing plates and vanes) it was $1500 parts alone used. And that is not accounting for your time or any the needed hardware that is also pricey. That makes the oem difs a not so favorable option considering the price of a new carbonetic or other manufacturers. So now the options are OEM used for ~$2000 or after market new for ~$2000? Tough choice IMHO. Especially when the gt2/3 guys are dumping their diffs for ~$3000 guard units because they don't like the OEM setups.
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#8
05-11-2012, 11:45 AM
Join Date: Oct 2008
Location: Portland Oregon
Posts: 1,696
Rep Power: 186
duplicate post.
Last edited by VAGscum; 05-11-2012 at 07:22 PM.
#9
05-11-2012, 11:47 AM
I installed a LSD in my car last year.
Couple of comments regarding this work.
It can be done with the transmission in the car. You will want to borrow/buy the factory tools VW 521/4 c/w VW 382/10 to do the backlash measurement and the dial gauge mount VW 387, the actual backlash is scribed on the ring gear since they vary to each ring/pinion set. Mine was 0.005" (scribed in mm). Don't bother trying to remove the factory bearing, if you ever need to go back to stock you can just swap it back in.
Procedure I used was to buy two sets of differential bearings, I then ground the inner sleeve of the bearing on my lathe so it would just slip fit on the new diff.
I borrowed the factory tools from a friend who owns a porsche repair shop, along with his assortment of shims (critical to have a large selection).
Remove the factory differential, replace the bearing races and install the new LSD diff (without ring gear), with a 2.5mm worth of shims on each side (you want to ensure a loose fit to measure NO preload). Apply a bit of gear oil to the bearings.
Install the outer cover with ALL bolts torqued down, install a dial gauge to measure preload on the passenger side, place the factory tool inside the diff and tighten to clamp the inner portion of the output shaft on the diff. Zero the dial gauge and push the diff all the way towards the gauge. This number will be how much more shim you need to get to zero preload. Then add an extra 0.40mm for the preload.
Once the preload is figured out you need to then setup the backlash. To do this you install the ring gear from the original diff onto the new LSD. Add all of the shims(required based on the preload measurement above) to passenger side of the diff (between the diff and the bearing, leave the original 2.5mm on the drivers side). This might not work depending on your LSD, basically the idea is to have more space between the ring and pinion so you can begin with too much backlash. DO NOT tighten all cover bolts down if the diff binds as you will side load the pinion. Keep checking that it rotates while tightening down the cover.
Install the diff again and torque down the cover with all bolts. Install the VW 521/4 tool and setup the dial gauge as per the manual (need to adjust the length of the measuring ball on the 382/10 tool to 91mm).
With a wrench on the 521/4 tool rock all the way back and set the zero on the dial gauge, then rock forward and note the backlash. If it is too high then you need to move some shims from the passenger side to the drivers side and repeat. Too low and move the some shims from the driver side to the passenger side. How much to move depends on how out it is, try 1mm at a time till your close. (which is why you need a ton of selection).
Also why I made my install bearings a tight slip fit, I ended up taking ~15 in/out to get mine right, the last 0.001" was the hardest.
Once the backlash is correct, take diff out and press on new bearing, reinstall and re-check backlash. Mine was exactly the same.
Do not cut corner, this isnt a pickup truck where close is good enough. I set my preload exactly to spec and my backlash as well, car has been on the track 10+ times since and lots of street miles with zero issue. The LSD is probably the best mod I've done to my car.
You can not do this correctly without the factory tool, don't even try. The tool clamps on the output shaft of the diff, if you attempt to do it some other way you will introduce the spider gear lash and your setup will end badly.
Couple of comments regarding this work.
It can be done with the transmission in the car. You will want to borrow/buy the factory tools VW 521/4 c/w VW 382/10 to do the backlash measurement and the dial gauge mount VW 387, the actual backlash is scribed on the ring gear since they vary to each ring/pinion set. Mine was 0.005" (scribed in mm). Don't bother trying to remove the factory bearing, if you ever need to go back to stock you can just swap it back in.
Procedure I used was to buy two sets of differential bearings, I then ground the inner sleeve of the bearing on my lathe so it would just slip fit on the new diff.
I borrowed the factory tools from a friend who owns a porsche repair shop, along with his assortment of shims (critical to have a large selection).
Remove the factory differential, replace the bearing races and install the new LSD diff (without ring gear), with a 2.5mm worth of shims on each side (you want to ensure a loose fit to measure NO preload). Apply a bit of gear oil to the bearings.
Install the outer cover with ALL bolts torqued down, install a dial gauge to measure preload on the passenger side, place the factory tool inside the diff and tighten to clamp the inner portion of the output shaft on the diff. Zero the dial gauge and push the diff all the way towards the gauge. This number will be how much more shim you need to get to zero preload. Then add an extra 0.40mm for the preload.
Once the preload is figured out you need to then setup the backlash. To do this you install the ring gear from the original diff onto the new LSD. Add all of the shims(required based on the preload measurement above) to passenger side of the diff (between the diff and the bearing, leave the original 2.5mm on the drivers side). This might not work depending on your LSD, basically the idea is to have more space between the ring and pinion so you can begin with too much backlash. DO NOT tighten all cover bolts down if the diff binds as you will side load the pinion. Keep checking that it rotates while tightening down the cover.
Install the diff again and torque down the cover with all bolts. Install the VW 521/4 tool and setup the dial gauge as per the manual (need to adjust the length of the measuring ball on the 382/10 tool to 91mm).
With a wrench on the 521/4 tool rock all the way back and set the zero on the dial gauge, then rock forward and note the backlash. If it is too high then you need to move some shims from the passenger side to the drivers side and repeat. Too low and move the some shims from the driver side to the passenger side. How much to move depends on how out it is, try 1mm at a time till your close. (which is why you need a ton of selection).
Also why I made my install bearings a tight slip fit, I ended up taking ~15 in/out to get mine right, the last 0.001" was the hardest.
Once the backlash is correct, take diff out and press on new bearing, reinstall and re-check backlash. Mine was exactly the same.
Do not cut corner, this isnt a pickup truck where close is good enough. I set my preload exactly to spec and my backlash as well, car has been on the track 10+ times since and lots of street miles with zero issue. The LSD is probably the best mod I've done to my car.
You can not do this correctly without the factory tool, don't even try. The tool clamps on the output shaft of the diff, if you attempt to do it some other way you will introduce the spider gear lash and your setup will end badly.
Last edited by Basic; 06-14-2012 at 10:42 AM.
#10
05-11-2012, 09:00 PM
Join Date: Oct 2008
Location: Portland Oregon
Posts: 1,696
Rep Power: 186 I installed a LSD in my car last year.
Couple of comments regarding this work.
It can be done with the transmission in the car. You will want to borrow/buy the factory tools VW 521/4 c/w VW 382/10 to do the backlash measurement and the dial gauge mount VW 387, the actual backlash is scribed on the ring gear since they vary to each ring/pinion set. Mine was 0.005" (scribed in mm). Don't bother trying to remove the factory bearing, if you ever need to go back to stock you can just swap it back in.
Procedure I used was to buy two sets of differential bearings, I then ground the inner sleeve of the bearing on my lathe so it would just slip fit on the new diff.
I borrowed the factory tools from a friend who owns a porsche repair shop, along with his assortment of shims (critical to have a large selection).
Remove the factory differential, replace the bearing races and install the new LSD diff, with a 2.5mm worth of shims on each side (you want to ensure a loose fit to measure NO preload). Apply a bit of gear oil to the bearings.
Install the outer cover with ALL bolts torqued down, install a dial gauge to measure preload on the passenger side, place the factory tool inside the diff and tighten to clamp the inner portion of the output shaft on the diff. Zero the dial gauge and push the diff all the way towards the gauge. This number will be how much more shim you need to get to zero preload. Then add an extra 0.40mm for the preload.
Once the preload is figured out you need to then setup the backlash. To do this you install the ring gear from the original diff onto the new LSD. Add all of the shims(required based on the preload measurement above) to passenger side of the diff (between the diff and the bearing, leave the original 2.5mm on the drivers side). This might not work depending on your LSD, basically the idea is to have more space between the ring and pinion so you can begin with too much backlash. DO NOT tighten all cover bolts down if the diff binds as you will side load the pinion. Keep checking that it rotates while tightening down the cover.
Install the diff again and torque down the cover with all bolts. Install the VW 521/4 tool and setup the dial gauge as per the manual (need to adjust the length of the measuring ball on the 382/10 tool to 91mm).
With a wrench on the 521/4 tool rock all the way back and set the zero on the dial gauge, then rock forward and note the backlash. If it is too high then you need to move some shims from the passenger side to the drivers side and repeat. Too low and move the some shims from the driver side to the passenger side. How much to move depends on how out it is, try 1mm at a time till your close. (which is why you need a ton of selection).
Also why I made my install bearings a tight slip fit, I ended up taking ~15 in/out to get mine right, the last 0.001" was the hardest.
Once the backlash is correct, take diff out and press on new bearing, reinstall and re-check backlash. Mine was exactly the same.
Do not cut corner, this isnt a pickup truck where close is good enough. I set my preload exactly to spec and my backlash as well, car has been on the track 10+ times since and lots of street miles with zero issue. The LSD is probably the best mod I've done to my car.
You can not do this correctly without the factory tool, don't even try. The tool clamps on the output shaft of the diff, if you attempt to do it some other way you will introduce the spider gear lash and your setup will end badly.
I'll throw up some pictures later of mine.
Couple of comments regarding this work.
It can be done with the transmission in the car. You will want to borrow/buy the factory tools VW 521/4 c/w VW 382/10 to do the backlash measurement and the dial gauge mount VW 387, the actual backlash is scribed on the ring gear since they vary to each ring/pinion set. Mine was 0.005" (scribed in mm). Don't bother trying to remove the factory bearing, if you ever need to go back to stock you can just swap it back in.
Procedure I used was to buy two sets of differential bearings, I then ground the inner sleeve of the bearing on my lathe so it would just slip fit on the new diff.
I borrowed the factory tools from a friend who owns a porsche repair shop, along with his assortment of shims (critical to have a large selection).
Remove the factory differential, replace the bearing races and install the new LSD diff, with a 2.5mm worth of shims on each side (you want to ensure a loose fit to measure NO preload). Apply a bit of gear oil to the bearings.
Install the outer cover with ALL bolts torqued down, install a dial gauge to measure preload on the passenger side, place the factory tool inside the diff and tighten to clamp the inner portion of the output shaft on the diff. Zero the dial gauge and push the diff all the way towards the gauge. This number will be how much more shim you need to get to zero preload. Then add an extra 0.40mm for the preload.
Once the preload is figured out you need to then setup the backlash. To do this you install the ring gear from the original diff onto the new LSD. Add all of the shims(required based on the preload measurement above) to passenger side of the diff (between the diff and the bearing, leave the original 2.5mm on the drivers side). This might not work depending on your LSD, basically the idea is to have more space between the ring and pinion so you can begin with too much backlash. DO NOT tighten all cover bolts down if the diff binds as you will side load the pinion. Keep checking that it rotates while tightening down the cover.
Install the diff again and torque down the cover with all bolts. Install the VW 521/4 tool and setup the dial gauge as per the manual (need to adjust the length of the measuring ball on the 382/10 tool to 91mm).
With a wrench on the 521/4 tool rock all the way back and set the zero on the dial gauge, then rock forward and note the backlash. If it is too high then you need to move some shims from the passenger side to the drivers side and repeat. Too low and move the some shims from the driver side to the passenger side. How much to move depends on how out it is, try 1mm at a time till your close. (which is why you need a ton of selection).
Also why I made my install bearings a tight slip fit, I ended up taking ~15 in/out to get mine right, the last 0.001" was the hardest.
Once the backlash is correct, take diff out and press on new bearing, reinstall and re-check backlash. Mine was exactly the same.
Do not cut corner, this isnt a pickup truck where close is good enough. I set my preload exactly to spec and my backlash as well, car has been on the track 10+ times since and lots of street miles with zero issue. The LSD is probably the best mod I've done to my car.
You can not do this correctly without the factory tool, don't even try. The tool clamps on the output shaft of the diff, if you attempt to do it some other way you will introduce the spider gear lash and your setup will end badly.
I'll throw up some pictures later of mine.
What diff did you install and what stub shafts did you use?
#12
05-13-2012, 05:01 PM
Join Date: Oct 2008
Location: Portland Oregon
Posts: 1,696
Rep Power: 186 Could you tell me a little about the new plates? Where do you get them and do you have the part numbers?
#14
05-14-2012, 03:09 PM
I installed a LSD in my car last year.
Couple of comments regarding this work.
It can be done with the transmission in the car. You will want to borrow/buy the factory tools VW 521/4 c/w VW 382/10 to do the backlash measurement and the dial gauge mount VW 387, the actual backlash is scribed on the ring gear since they vary to each ring/pinion set. Mine was 0.005" (scribed in mm). Don't bother trying to remove the factory bearing, if you ever need to go back to stock you can just swap it back in.
Procedure I used was to buy two sets of differential bearings, I then ground the inner sleeve of the bearing on my lathe so it would just slip fit on the new diff.
I borrowed the factory tools from a friend who owns a porsche repair shop, along with his assortment of shims (critical to have a large selection).
Remove the factory differential, replace the bearing races and install the new LSD diff, with a 2.5mm worth of shims on each side (you want to ensure a loose fit to measure NO preload). Apply a bit of gear oil to the bearings.
Install the outer cover with ALL bolts torqued down, install a dial gauge to measure preload on the passenger side, place the factory tool inside the diff and tighten to clamp the inner portion of the output shaft on the diff. Zero the dial gauge and push the diff all the way towards the gauge. This number will be how much more shim you need to get to zero preload. Then add an extra 0.40mm for the preload.
Once the preload is figured out you need to then setup the backlash. To do this you install the ring gear from the original diff onto the new LSD. Add all of the shims(required based on the preload measurement above) to passenger side of the diff (between the diff and the bearing, leave the original 2.5mm on the drivers side). This might not work depending on your LSD, basically the idea is to have more space between the ring and pinion so you can begin with too much backlash. DO NOT tighten all cover bolts down if the diff binds as you will side load the pinion. Keep checking that it rotates while tightening down the cover.
Install the diff again and torque down the cover with all bolts. Install the VW 521/4 tool and setup the dial gauge as per the manual (need to adjust the length of the measuring ball on the 382/10 tool to 91mm).
With a wrench on the 521/4 tool rock all the way back and set the zero on the dial gauge, then rock forward and note the backlash. If it is too high then you need to move some shims from the passenger side to the drivers side and repeat. Too low and move the some shims from the driver side to the passenger side. How much to move depends on how out it is, try 1mm at a time till your close. (which is why you need a ton of selection).
Also why I made my install bearings a tight slip fit, I ended up taking ~15 in/out to get mine right, the last 0.001" was the hardest.
Once the backlash is correct, take diff out and press on new bearing, reinstall and re-check backlash. Mine was exactly the same.
Do not cut corner, this isnt a pickup truck where close is good enough. I set my preload exactly to spec and my backlash as well, car has been on the track 10+ times since and lots of street miles with zero issue. The LSD is probably the best mod I've done to my car.
You can not do this correctly without the factory tool, don't even try. The tool clamps on the output shaft of the diff, if you attempt to do it some other way you will introduce the spider gear lash and your setup will end badly.
I'll throw up some pictures later of mine.
Couple of comments regarding this work.
It can be done with the transmission in the car. You will want to borrow/buy the factory tools VW 521/4 c/w VW 382/10 to do the backlash measurement and the dial gauge mount VW 387, the actual backlash is scribed on the ring gear since they vary to each ring/pinion set. Mine was 0.005" (scribed in mm). Don't bother trying to remove the factory bearing, if you ever need to go back to stock you can just swap it back in.
Procedure I used was to buy two sets of differential bearings, I then ground the inner sleeve of the bearing on my lathe so it would just slip fit on the new diff.
I borrowed the factory tools from a friend who owns a porsche repair shop, along with his assortment of shims (critical to have a large selection).
Remove the factory differential, replace the bearing races and install the new LSD diff, with a 2.5mm worth of shims on each side (you want to ensure a loose fit to measure NO preload). Apply a bit of gear oil to the bearings.
Install the outer cover with ALL bolts torqued down, install a dial gauge to measure preload on the passenger side, place the factory tool inside the diff and tighten to clamp the inner portion of the output shaft on the diff. Zero the dial gauge and push the diff all the way towards the gauge. This number will be how much more shim you need to get to zero preload. Then add an extra 0.40mm for the preload.
Once the preload is figured out you need to then setup the backlash. To do this you install the ring gear from the original diff onto the new LSD. Add all of the shims(required based on the preload measurement above) to passenger side of the diff (between the diff and the bearing, leave the original 2.5mm on the drivers side). This might not work depending on your LSD, basically the idea is to have more space between the ring and pinion so you can begin with too much backlash. DO NOT tighten all cover bolts down if the diff binds as you will side load the pinion. Keep checking that it rotates while tightening down the cover.
Install the diff again and torque down the cover with all bolts. Install the VW 521/4 tool and setup the dial gauge as per the manual (need to adjust the length of the measuring ball on the 382/10 tool to 91mm).
With a wrench on the 521/4 tool rock all the way back and set the zero on the dial gauge, then rock forward and note the backlash. If it is too high then you need to move some shims from the passenger side to the drivers side and repeat. Too low and move the some shims from the driver side to the passenger side. How much to move depends on how out it is, try 1mm at a time till your close. (which is why you need a ton of selection).
Also why I made my install bearings a tight slip fit, I ended up taking ~15 in/out to get mine right, the last 0.001" was the hardest.
Once the backlash is correct, take diff out and press on new bearing, reinstall and re-check backlash. Mine was exactly the same.
Do not cut corner, this isnt a pickup truck where close is good enough. I set my preload exactly to spec and my backlash as well, car has been on the track 10+ times since and lots of street miles with zero issue. The LSD is probably the best mod I've done to my car.
You can not do this correctly without the factory tool, don't even try. The tool clamps on the output shaft of the diff, if you attempt to do it some other way you will introduce the spider gear lash and your setup will end badly.
I'll throw up some pictures later of mine.
#15
05-14-2012, 09:39 PM
This isnt a simple job, I have done tons of this kind of work and have a garage full of tools. Wouldn't recommend attempting this job as a diy. If your having a shop do the work, this info can help you determine if they can handle it properly.
Thanks for the rep. Hope it helps someone out.
Thanks for the rep. Hope it helps someone out.