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    Thread: 02M preload info for Dub-Nub

    1. Member Broke's Avatar
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      05-16-2012 03:07 PM #1
      The IM only allows so many characters, so I decided to just post it as a thread, then others can gather info from it through searches. After spending 2 full hours researching and typing, I figure the info is good enough to save it in a thread

      Original IM:
      Quote Originally Posted by Dub-Nub
      Hey Broke, thanks again for the input. I have a budde who works at VW dealer locally and he is going to let me borrow the tools that I need, which is great. I started the installation yesterday by taking the transmission off. Currently doing research on the shimming, which is what i am most concerned about. Differnet threads have different information.

      In my thread you mentioned starting with a .65mm shim, which is what i measured for the non-changing shim. In another thread for 02m i saw you mention a 1.7mm shim.

      Another LSD thread from TDIClub indicates some preload measurements

      3) I shoot for .010-.014" of preload. The math goes something like this; Free play measurement + .002" or .003" for what preload you'll lose because of the case sealant + .010" to .014" = shim thickness.

      Here was mine: Original shim was .039". Free play was .024". 39-24=.015".
      .015" - .003"= ~.012" preload with original shim. Since that's in spec, no new shim required.

      I have the bentley but was unable to find the correct procedure for the 02m. Maybe it is because i have the paperback edition?

      Reading though the steps that you posted

      -Mount a dial onto the casing and diff and zero it with 1mm preload, and lift the diff up and down, noting the amount of play recorded by the dial.
      -Add 0.30mm shim preload to the measured play and that is the final shim.

      When i move the diff up and down and i get .15 play then i add a .45 shim, ya?
      Reply:

      Quote Originally Posted by Dub-Nub
      Hey Broke, thanks again for the input. I have a budde who works at VW dealer locally and he is going to let me borrow the tools that I need, which is great.
      Hit him up for the elsa repair database info. The dealer will get updates to have the latest info. The elsa database has the factory repair info that is used by Bentley publishers to make the manuals.
      Verify what VW states for your trans preload.

      The info I have covers these codes: EDJ, ERR, FML, FSR, FZQ, FZR,
      It is older info, so it might have been updated.

      Quote Originally Posted by Dub-Nub
      In my thread you mentioned starting with a .65mm shim, which is what i measured for the non-changing shim. In another thread for 02m i saw you mention a 1.7mm shim.
      The 0.65 is the constant shim size for those shims in the bellhousing half of the casing. The gearbox half of the casing gets the adjustment (changing) shims.

      The 02M with the dual output shafts has two 0.65mm shims in the bellhousing... one for the output shaft for 5th, 6th, and reverse, and then one for the diff.
      The output shaft for 1st, 2nd, 3rd, and 4th doesn't have a shim under the bellhousing race. It has an oil deflection ring.
      The input shaft has no shim.

      That should be the 4 taper bearings... diff, input, output#1 and output#2.... 2 don't get shims, the other 2 get standard non-changing 0.65mm shims.

      1.7mm is the starting shim size for the OTHER end of the output shafts. The shim you put into the gearbox half of the casing. It is the shim you start with to begin the procedure of determining the correct shim needed.

      Quote Originally Posted by Dub-Nub
      3) I shoot for .010-.014" of preload.
      It depends on what shaft is being done. For the input shaft, no preload. For the diff bearings, 0.012" and for the output shafts it is 0.008".... technically VW wants 0.20mm preload on the outputs, and 0.30mm preload on the diff which is *about* 0.012" and 0.008" when converted.

      Quote Originally Posted by Dub-Nub
      The math goes something like this; Free play measurement + .002" or .003" for what preload you'll lose because of the case sealant + .010" to .014" = shim thickness.
      VW makes no mention of compensation for case sealant. In my experience, it is minimal and in theory should be zero. It should fill micro imperfections in the case sealing surface. It is not a gasket maker and won't result in a thick barrier between the 2 case halves. When it is applied properly it should allow the case halves to come into full contact with each other, just as if there were nothing on them. The sealant should be squeezed out and the preload wouldn't be affected.
      What effect there would be would be extremely minimal. I might one day test it to be 100% sure, but my experience using the sealant and opening those trans that had sealant originally tells me there is no need to add any shim size or preload to make up for it.
      The only mention VW makes of the sealant, which DOES support the claim of the ClubTDI poster, is that the 2 case halves should be free of sealant before starting the preload procedure.
      I suspect this step is added to ensure that any balled up pieces of old sealant that might be on the surfaces is removed fully.
      Sooo... VW does say to remove any old sealant, but then they do not make any concessions for the adding of sealant later... it tells me they aren't that worried about the thickness of the sealant to be added later.

      Quote Originally Posted by Dub-Nub
      Here was mine: Original shim was .039". Free play was .024". 39-24=.015".
      .015" - .003"= ~.012" preload with original shim. Since that's in spec, no new shim required.
      Converted to metric, that would read:

      Original shim was 0.99mm. Free play was .61mm. 99-61=.38mm.
      .38mm - .08mm= ~.30mm preload with original shim. Since that's in spec, no new shim required.

      If that is one of the output shafts, which the procedure he lists suggests, then he is over the VW spec by 50%.

      If he measured .61mm free play he would subtract that from the 0.99mm shim to get .38mm then add the VW preload constant of 0.20mm and you get 0.58mm, so a 0.60mm shim is what he needed.

      Quote Originally Posted by Dub-Nub
      I have the bentley but was unable to find the correct procedure for the 02m. Maybe it is because i have the paperback edition?
      They might not include the detailed trans rebuild info in the Bentley. I know the MK3 book doesn't have the 020 info, but the MK1 and MK2 books do.... so I'm not sure on that one, but I know not all have the detailed trans rebuild info in them.

      Quote Originally Posted by Dub-Nub
      Reading though the steps that you posted

      -Mount a dial onto the casing and diff and zero it with 1mm preload, and lift the diff up and down, noting the amount of play recorded by the dial.
      -Add 0.30mm shim preload to the measured play and that is the final shim.

      When i move the diff up and down and i get .15 play then i add a .45 shim, ya?
      With a 0.65mm shim under the bellhousing bearing, and no shim in the gearbox half, if you lift the diff 0.15mm, then yes, you need a 0.45mm shim.
      They state to press the diff into the bellhousing bearing and spin it 8 times, then press it into the gearbox bearing and spin it 8 times, then lift and measure. They want the bearings settled. They want you to press to ensure the rollers roll and don't slide or skid. This will settle them.

      DIFF ADJUSTMENT
      The diff is like the 020.... a constant (0.65mm) shim in the bellhousing, nothing in the gearbox, settle bearings, measure play, add play to preload constant of 0.30mm and that is the shim needed.

      INPUT SHAFT ADJUSTMENT
      For the input shaft, they want no preload. They want to have it so it is not loose, but has no preload constant value. The shaft should move 0.065mm-0.150mm when done.
      They want both output shafts installed and preload adjusted before adjusting the input.
      You install it with no shim in the bellhousing, and none in the gearbox. Measure the play. The shim will be slightly less than the play (to ensure a little play remains). The shim goes in the gearbox half.

      OUTPUT SHAFTS ADJUSTMENT
      For the output shafts... one gets a standard 0.65mm shim under (the shaft with 5th, 6th, and reverse) the race in the bellhousing, the other shaft (1st-4th) gets no shim under the race in the bellhousing, just an oil deflection ring.
      Preload one shaft at a time, no other shafts in the trans with it.
      Settle bearings prior to measuring.
      Install a 1.70mm shim into the gearbox half.
      Put the case together, tighten the bolts. The 1.7mm will be too thick, and you will "crush" the shaft with the casing.
      Now, put the dial on, attach it to the bellhousing and have it resting on top of the gearbox. We want to measure the movement of the top of the casing from the bottom, so the movement of the gearbox half away form the bellhousing.
      When the dial is in place, zero it with 1mm preload. This means press the dial in 1mm until it gets back to showing zero again on the face. This way the dial is working from the middle of the operation range. That's what they mean when they want the dial preloaded 1mm but zeroed.
      With the dial in place, showing zero, 1mm preload... loosen the casing bolts evenly until the shaft is no longer "crushed" and can move.
      Note the dial measurement. As you loosened the bolts, the gearbox half lifted up away from the bellhousing. As soon as the shaft is free to move, look at the dial.

      For an example, let's say you measured 0.70mm on the dial as you loosened the casing bolts.

      Your 1.70mm shim crushed it. Releasing 0.70 of casing bolt no longer crushed it. Thus, a 1.00mm shim would eat up ALL the play, but NOT crush the shaft.
      VW wants it crushed. They want exactly 0.20mm of crushing to take place.
      We now know that 1.70 crushes it, and 1.00mm is zero-crush and zero-slop. Add on the 0.20mm crush VW wants and you end up with 1.00 + 0.20mm = 1.20mm
      You need a 1.20mm shim to get the right amount of "crush" or constant preload for that shaft.
      Repeat with the other output shaft.

      I think that is it.
      For the record... I've never done any of the above. I don't work on the 02M. I do know how to preload a VW 020 trans and I have the 02M info so the above procedure should be technically correct and accurate. If you find any errors, let me know but MY excuse is that I don't work on them
      020 trans info pages - www.BrokeVW.com
      NEW 0.7619 5th gears for the 020
      NEW 020 reverse gears
      '86 GTI 8V 2.0L -'88 Scirocco 16V - '10 F150 4x4

    2. Member Dub-Nub's Avatar
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      05-16-2012 03:45 PM #2
      Thanks again

      I will send you something when i am done with this installation, it may not be much but it's something.

      I am going to get with my guy and have him check ELSA for latest procedures and let you know what they are.

      This is good learning material, as confusing as it is for someone who has not opened it. I have to try and picture everything in my head.

      I found this good PDF file.

      http://www.volkspage.net/technik/ssp/ssp/SSP_205.pdf

      Lots of good information.

      Only the diff needs to be shimmed for me since i will not touch the output shafts

      Edit:

      Including original thread regarding shims that i have which Broke helped out

      http://forums.vwvortex.com/showthrea...s-for-end-play
      Last edited by Dub-Nub; 05-16-2012 at 04:04 PM.

    3. Member bdfcorrado's Avatar
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      02-09-2013 02:27 AM #3
      Im gonna use this .

      thx

    4. 11-05-2014 05:36 PM #4
      Hi,

      Thanks so much for sharing all this. Where to find a VW manual about 02m rebuild instruction?

    5. Member Broke's Avatar
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      11-06-2014 09:21 AM #5
      Quote Originally Posted by mikeyanxu View Post
      Hi,

      Thanks so much for sharing all this. Where to find a VW manual about 02m rebuild instruction?
      I had some paper copies of a manual I bought from ebay, no idea where that person got them, unless they printed them up from a dealer they worked at or something.
      Unfortunately my papers are in storage at the moment, but the preload info should all be contained in this thread.
      020 trans info pages - www.BrokeVW.com
      NEW 0.7619 5th gears for the 020
      NEW 020 reverse gears
      '86 GTI 8V 2.0L -'88 Scirocco 16V - '10 F150 4x4

    6. 11-22-2014 07:45 PM #6
      Hello,

      I reassembled the 02m gearbox. I only changed all shaft seals and improved the shift forks. Now, once reassembled with bolts torqued to spec, the input shaft can be spun freely. However, the spring flange shafts are difficult to spin by hand (differential is hard to turn by hand). No bearing/race was changed or touched. I doubt by driving the seals would alter the bearing preload. I have not added any lubricant in it yet. I was going to wait after the case sealant cures then add gear lube. I can't remember if the flange shafts were difficult to spin or not before tearing down. Is this normal? What is the purpose of the spring and a copper/brass looking conical piece in the flange shaft for? Thank you.

    7. Member Broke's Avatar
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      12-05-2014 07:25 AM #7
      Quote Originally Posted by mikeyanxu View Post
      However, the spring flange shafts are difficult to spin by hand (differential is hard to turn by hand).
      They shouldn't be super hard to turn. I just got your IM this morning from weeks ago and replied to it, but they should be fairly easy to spin when not in gear, and harder when you are in gear as you'd be spinning the input shaft with the flanges when in gear.

      When in 5th, it will be easier to spin the flanges (just like trying to push start a car is easier to turn the engine over in the 3-5 gears vs. 1st or 2nd), when in 1st the flanges will be harder to spin by hand.

      The opposite is true when spinning the input shaft... easier in 1st and 2nd, harder in 3rd-5th to spin the input by hand. This is why a bad clutch is more likely to slip in 3rd-5th and 1st and 2nd, because of the mechanical advantage the gear ratios offer.

      If you need more force than is required to open a new jar of pickles or something, that is reason for concern. You should be able to grab both flanges, spin them the same direction, and be able to spin them both when the trans is out of gear without much force needed.

      Quote Originally Posted by mikeyanxu View Post
      No bearing/race was changed or touched. I doubt by driving the seals would alter the bearing preload.
      If no bearings or races were touched, then the preload isn't likely altered. The seals won't change the preload.
      When you open it though, the diff relies on the 2 case halves to make up the preload, so you will change the preload opening the case, but then installing it back should restore the preload. Since there is no paper gasket that can crush then you shouldn't alter the preload by re-sealing it with the sealant paste, that should allow the 2 case halves to go back together as they were before you opened it.
      If something like debris or a piece of lint or something got into the bearings while it was open, it could cause a bearing roller to start dragging or sliding instead of rolling, but even then it shouldn't bind the flanges up to the point of being unable to spin them or requiring a ton of force to do so.

      Quote Originally Posted by mikeyanxu View Post
      I have not added any lubricant in it yet. I was going to wait after the case sealant cures then add gear lube.
      It will help things spin, but it shouldn't make the difference in them spinning or not... the lube will let them spin for a long time under load at speed, but a perfectly dry bearing will still spin pretty easily at low loads and speeds such as spinning the parts over by hand.

      Quote Originally Posted by mikeyanxu View Post
      I can't remember if the flange shafts were difficult to spin or not before tearing down. Is this normal?
      I don't know the 02M very well at all, but generally they are not hard to spin over by hand.

      Quote Originally Posted by mikeyanxu View Post
      What is the purpose of the spring and a copper/brass looking conical piece in the flange shaft for?
      I'm assuming it is like the 020 which was the first trans to get those springs and cones behind the flanges.... they stop the stub axle shafts coming out of the diff from rattling at stop lights. That's why VW installed them to start with in 1983.... to address owner complaints of rattle noises.

      The bronze cone will compress onto the stub axle shaft as the cone is pressed into the diff carrier by the flange and spring. This clamps the cone onto the stub axle shaft, and binds it against the diff carrier. When driving in a straight line, the carrier, cone, and stub axle all spin at the same speed. The effect of the cone binding the stub axle never comes into play when driving straight. When sitting and idling at a stop light, the cones will hold the stub axles in place and stop them rattling.

      When you corner though, the stub axles will move at different speeds to each other, and in relation to the speed of the diff carrier. The carrier spins at the speed you tell it via engine throttle... the ring gear spins the carrier, and that's it. Inside the carrier are the 4 diff gears, and in those we find the differential in the 2 stub axles speed.... in a corner, the inside tire has to spin more slowly, and the outside tire has to spin more quickly. The ring gear doesn't change... this is how a basic diff works... it allows the 2 drive tires to spin at different speeds to each other and in relation to the diff carrier.

      When you corner, the bronze cones are being worn as they are slipping against the stub axle spinning inside them, or they slip against the diff carrier, as they then start to fight the stub axle from spinning by trying to bind the axle to the speed of the carrier. They don't put up much of a fight, it's just a bit of pressure by a bronze ring on the stub axle, so the axle has no problems spinning inside the clamping bronze cone and you can corner without feeling anything binding the axles. They are still there, still preventing the stubs from rattling, but they aren't stopping the axles from spinning at different rates in relation to each other or the carrier.

      So, in short, they're to stop rattle noises.

      If you spin both flanges together at the same time in the same direction, then the cones are never noticed. If you hold one flange and try to spin the other (one wheel burn out simulation) then you'd feel the cones working and binding the stub axles, and it would be harder to spin by hand, but spinning both the same direction should be fairly easy.
      020 trans info pages - www.BrokeVW.com
      NEW 0.7619 5th gears for the 020
      NEW 020 reverse gears
      '86 GTI 8V 2.0L -'88 Scirocco 16V - '10 F150 4x4

    8. 12-05-2014 12:31 PM #8
      Thank you so so much Broke. In my case, it is the same difficulty to spin the flange shafts in opposite and in the same direction. So, in addition to the anti rattle device, in theory, the brass conical rings also function as slightly limited slip devices. Say, 5% or even less? I took off one of the flange shafts then I was able to spin the opposite side flange shaft. I can tell that the differential (cage) was spun instead of the ring gear. So, whatever caused my symptom, it must be in one of the 6 taper roller bearings. I put 1 liter vw gearlube in it and I will roll it around to see if that will make a difference. Just for my learning here, would you lube the bearings and gears prior to reassembly? I degreased with solvent and dried all the internal components before reassembly. I wanted to ensure that non of the lube drip down to the case sealant before it cures. I am curious what is the correct way to do?

    9. Member Broke's Avatar
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      12-06-2014 10:28 AM #9
      Quote Originally Posted by mikeyanxu View Post
      Thank you so so much Broke. In my case, it is the same difficulty to spin the flange shafts in opposite and in the same direction.
      They should be easier to spin together the same direction when the trans is out of gear, so something is amiss.
      When spun together the same direction, you're basically spinning the diff+spider gears+stub axles+flanges+ring gear as one unit, the ring gear spins the output shaft, and the 1-5 gears spin on their bearings, while the input shaft doesn't spin or spins slowly just because the drag between the bearings and gears cause it to spin, but the input shaft isn't connected to the output shaft when a gear isn't selected.

      Spinning the flanges opposite of each other is causing the diff to "break" and you will be feeling the binding action of the bronze conical thrust rings and springs behind the flanges. In this case, the flanges+stub axles+spider gears spin, but the diff carrier+ring gear do not spin, so you're moving less parts than previously inside the trans, but the binding effect of the bronze cones will be felt and it results in the flanges being harder to spin opposite directions than it is to spin them the same direction together.

      Quote Originally Posted by mikeyanxu View Post
      So, in addition to the anti rattle device, in theory, the brass conical rings also function as slightly limited slip devices. Say, 5% or even less?
      Exactly.
      When VW introduced them to the 020 trans in 1983 it wasn't long before someone had a car on the lift or in the air and noticed the tires spun together when you'd spin one by hand... this was the effect of the binding action on the shafts. Prior to this you'd spin one wheel in the air and the other drive tire would spin the opposite direction, it was a fully open diff with no binding or resistance, or preload.
      The springs and cones introduced preload to the diff, about 20% or so.
      Not long after Velocity came up with the idea of increasing the spring pressure on the bronze cone, in an effort to make it bind up on the stub axle a little tighter. This resulted in the 40% and 80% diff shim kits available for the 020, now sold by Peloquin.

      The end result, besides stopping the rattling noises, was that owners found that when in snow or mud they were less likely to do a one wheel burn out.... if you didn't push it hard and apply too much throttle then the springs and cones were able to effectively "hide" the small differences in traction between the 2 drive wheels.
      Normally, if there is just a small bit of difference in traction, the wheel easiest to spin will spin and the other wheel does nothing... say the road has snow on it evenly and one side is in the shade and has a layer of ice on it... normally the tire on ice would just spin when you tried to accelerate because the diff could "see" the difference between the traction of the 2 drive wheels by reading the resistance of each tire. Just a couple ft-lbs of difference and the diff would "break" and unload into the tire with the least amount of traction.

      Now, if you bind both sides evenly (with the springs and cones) then you will have 30 ft-lbs or so of resistance built into both sides of the diff automatically... which means the difference in the traction for each drive tire must be larger (over 30 ft-lbs) before you get one wheel spin. The diff won't notice one side is just 10 ft-lbs easier to spin than the other when 30 ft-lbs of binding is happening on each side of the diff. It just knows that both sides are resisting and it splits the power evenly to both wheels until there is a big enough difference in traction. If you mash the throttle hard enough you'll overcome the binding of the cones and one wheel will start spinning. If you ease into it you find both tires spin even though one is easier to spin than the other.

      This is where the idea of it being a "poor mans posi" or "poor mans LSD" came into play.

      I have more info about them on this page http://brokevw.com/difftest.html

      Keep in mind your 02M may have the stub axles attached to the flanges... with the 020 the flange and stub axle are individual parts, on the 02A/J I believe the stub axles are part of the flanges so you pop the flange and stub axle into the diff as one part, but the operation of the cones and springs are the same.

      Quote Originally Posted by mikeyanxu View Post
      I took off one of the flange shafts then I was able to spin the opposite side flange shaft. I can tell that the differential (cage) was spun instead of the ring gear.
      If the ring gear didn't spin, the diff carrier (cast housing that holds the 4 spider gears) also didn't spin, the ring is riveted to the carrier.
      This also means the taper diff bearings weren't spinning, so with the flange removed you would see the taper bearing, if it wasn't moving then the carrier+ring wasn't moving, and only the spider gears inside would be spinning.

      Quote Originally Posted by mikeyanxu View Post
      Just for my learning here, would you lube the bearings and gears prior to reassembly? I degreased with solvent and dried all the internal components before reassembly. I wanted to ensure that non of the lube drip down to the case sealant before it cures. I am curious what is the correct way to do?
      Bearings are always installed lubed. I generally hit them with brake cleaner and dry with compressed air so they are 100% clean, then I oil with a little trans fluid just to wet the roller elements and the races. They are installed wet and the preload procedures will call for them to be oiled when measuring the preloads.
      I use a oil can that lets me add oil by the drop to the bearings, so I assemble the taper bearing cone and cup (bearing and race) together in my hand dry, add a little oil by the drop around the rollers where the bearing and race meet, then spin them in my hand to distribute the oil around the bearing. This leaves them lubed, but not dripping so nothing runs out.
      020 trans info pages - www.BrokeVW.com
      NEW 0.7619 5th gears for the 020
      NEW 020 reverse gears
      '86 GTI 8V 2.0L -'88 Scirocco 16V - '10 F150 4x4

    10. 12-18-2014 02:12 PM #10
      Thank you Broke. It is been long enough and I made progress so I think I owe you guys some update.
      I added 1 liter gearlube and rotated the gearbox on the bench. Now I could easily spin the flange shafts in neutral and in gears. I can tell the difference in mechanical advantages of each gear. And yes I could spin the flange shafts even if it is on 6th gear. Just like you described, in neutral, when I spin the flange shafts, the input shaft also spins due to drag. The input shaft can be held still while flange shafts are spun (when in neutral). I am amazed by how much the lubrication makes on bearings. Well, I figured that 0.x mm of compression/preload on dry taper roller bearings really hold them together from rolling. I wish I lubed the bearings and gears prior to assemble. I was just too overly concerned about oil dripping on the case flange and affecting the sealant to cure properly. Anyways, now the gearbox and engine are back in the car. I want to say thank you for all of your help.

      One more thing, would the 40% and 80% diff shim kits cause excessive wear on the brass cones? They will wear a lot more than stock ones when the vehicle turns.

      Quote Originally Posted by Broke View Post
      They should be easier to spin together the same direction when the trans is out of gear, so something is amiss.
      When spun together the same direction, you're basically spinning the diff+spider gears+stub axles+flanges+ring gear as one unit, the ring gear spins the output shaft, and the 1-5 gears spin on their bearings, while the input shaft doesn't spin or spins slowly just because the drag between the bearings and gears cause it to spin, but the input shaft isn't connected to the output shaft when a gear isn't selected.

      Spinning the flanges opposite of each other is causing the diff to "break" and you will be feeling the binding action of the bronze conical thrust rings and springs behind the flanges. In this case, the flanges+stub axles+spider gears spin, but the diff carrier+ring gear do not spin, so you're moving less parts than previously inside the trans, but the binding effect of the bronze cones will be felt and it results in the flanges being harder to spin opposite directions than it is to spin them the same direction together.



      Exactly.
      When VW introduced them to the 020 trans in 1983 it wasn't long before someone had a car on the lift or in the air and noticed the tires spun together when you'd spin one by hand... this was the effect of the binding action on the shafts. Prior to this you'd spin one wheel in the air and the other drive tire would spin the opposite direction, it was a fully open diff with no binding or resistance, or preload.
      The springs and cones introduced preload to the diff, about 20% or so.
      Not long after Velocity came up with the idea of increasing the spring pressure on the bronze cone, in an effort to make it bind up on the stub axle a little tighter. This resulted in the 40% and 80% diff shim kits available for the 020, now sold by Peloquin.

      The end result, besides stopping the rattling noises, was that owners found that when in snow or mud they were less likely to do a one wheel burn out.... if you didn't push it hard and apply too much throttle then the springs and cones were able to effectively "hide" the small differences in traction between the 2 drive wheels.
      Normally, if there is just a small bit of difference in traction, the wheel easiest to spin will spin and the other wheel does nothing... say the road has snow on it evenly and one side is in the shade and has a layer of ice on it... normally the tire on ice would just spin when you tried to accelerate because the diff could "see" the difference between the traction of the 2 drive wheels by reading the resistance of each tire. Just a couple ft-lbs of difference and the diff would "break" and unload into the tire with the least amount of traction.

      Now, if you bind both sides evenly (with the springs and cones) then you will have 30 ft-lbs or so of resistance built into both sides of the diff automatically... which means the difference in the traction for each drive tire must be larger (over 30 ft-lbs) before you get one wheel spin. The diff won't notice one side is just 10 ft-lbs easier to spin than the other when 30 ft-lbs of binding is happening on each side of the diff. It just knows that both sides are resisting and it splits the power evenly to both wheels until there is a big enough difference in traction. If you mash the throttle hard enough you'll overcome the binding of the cones and one wheel will start spinning. If you ease into it you find both tires spin even though one is easier to spin than the other.

      This is where the idea of it being a "poor mans posi" or "poor mans LSD" came into play.

      I have more info about them on this page http://brokevw.com/difftest.html

      Keep in mind your 02M may have the stub axles attached to the flanges... with the 020 the flange and stub axle are individual parts, on the 02A/J I believe the stub axles are part of the flanges so you pop the flange and stub axle into the diff as one part, but the operation of the cones and springs are the same.



      If the ring gear didn't spin, the diff carrier (cast housing that holds the 4 spider gears) also didn't spin, the ring is riveted to the carrier.
      This also means the taper diff bearings weren't spinning, so with the flange removed you would see the taper bearing, if it wasn't moving then the carrier+ring wasn't moving, and only the spider gears inside would be spinning.



      Bearings are always installed lubed. I generally hit them with brake cleaner and dry with compressed air so they are 100% clean, then I oil with a little trans fluid just to wet the roller elements and the races. They are installed wet and the preload procedures will call for them to be oiled when measuring the preloads.
      I use a oil can that lets me add oil by the drop to the bearings, so I assemble the taper bearing cone and cup (bearing and race) together in my hand dry, add a little oil by the drop around the rollers where the bearing and race meet, then spin them in my hand to distribute the oil around the bearing. This leaves them lubed, but not dripping so nothing runs out.
      Last edited by mikeyanxu; 12-18-2014 at 02:15 PM.

    11. Member Broke's Avatar
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      Aug 13th, 2001
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      86 GTI 2.0L, 88 Scirocco 16V, 2010 F150 STX
      Yesterday 04:18 AM #11
      Quote Originally Posted by mikeyanxu View Post
      I added 1 liter gearlube and rotated the gearbox on the bench. Now I could easily spin the flange shafts in neutral and in gears.
      I admit I have never tried preloading without some lube on the bearings, but I am surprised it made such a difference at the low speeds and loads present when turning the shafts by hand.
      I would have thought the force needed to spin them would be slightly increased, but not so great as to make them difficult to spin slowly by hand.
      I've learned something new, thanks!

      Quote Originally Posted by mikeyanxu View Post
      One more thing, would the 40% and 80% diff shim kits cause excessive wear on the brass cones? They will wear a lot more than stock ones when the vehicle turns.
      They do wear more, but as I was told, it is a compromise between increased diff preload and wear. I was told the brass rings in the 80% kits will last about one or two race seasons before they start to wear to a point of needing replacement. The Peloquin brass rings in the 40% and 80% kits are supposed to be a different hardness material but I am unable to verify this myself.
      There is also increased wear on the plastic thrust piece (in the case of the 020 trans, I'm not sure what is in the other trans types) in the diff behind the spider gears, as well as on the 2 large spider gears that contact the plastic thrust piece, but as I was told, it is a negligible amount of wear there.

      So, yes, there is accelerated wear on the parts when using a 40% or 80% kit, but it is minimal in relation to the increased preload and performance of the diff in most case, for most people. If you never push the car and have no need for it, there is no point in installing the kit. If you have a need for it on a regular basis (like when competing) then the increased wear would be acceptable.

      Brian
      020 trans info pages - www.BrokeVW.com
      NEW 0.7619 5th gears for the 020
      NEW 020 reverse gears
      '86 GTI 8V 2.0L -'88 Scirocco 16V - '10 F150 4x4

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