You honestly think I would run an old bolt that had been cut three ways? Really Eddie, it's a tool jig to hold the pulley to allow accurate drilling. I wrongly assumed those on here would know what I was driving at, in fact I think I even mention it in my build thread
At home now, pulled out my Red Mk2 Haynes, that somebody I mentioned early was correct, 200nm and 148lbft for the 8v and 180nm and 133lbft for the 1.8 16v engine. (Interesting the 8v has more torque than the 16v). Lets discuss why the Haynes differs in procedure, it's defiantly not a typo as the 16v engine is a different figure to the 8v engines. thoughts?
The bolt lengths differ and this will effect the torque setting but why does VW not differ in their procedure for 8v and 16v both are 90nm by 90deg? Or am I mistaken.
Taken from a Recreational Aircraft Association of New Zealand (RAANZ) Tech Officer who wrote an article on thread fasteners. However, it depends on the type of loctite you use, stick or liquid. (248 is a stick). Liquid seems to act have same K values as oiled bolts.Looking at the data sheet for loctite 248 the friction coefficent drops 0.01 with the product, so none oiled steel bolt, goes from std 0.2 to 0.19 with product. The above has oiled bolts K at 0.15 which is close to Eddies K @ 0.14. Accurate K values are hard to come by, but if loctite say in their data sheet it effects it this much or not at all, you are best to trust them. I wonder if Eddie has access to K values from his work? Could be a handy piece of data to have in a table on the forum.
Here is my advice, Doweling is only to regain the position of the lower pulley if the old keyway has been swiped off due to a loose bolt. Dowels are case hardned with ductile cores and can be 3-4mm in diameter. I think ALL of you will realize that these cannot take any torque loads. They are are only to resist the torque forces present from the underside of bolt head while tightening if the crank has been locked - they stop the pulley turning on crank nose while tightening. A flies leg could be used for positioning dowel if you were to lock both the crank, and pulley with a crank lock tool, and a timing gear lock tool - shown in thread. The dowels never see shear forces in use. If they did, this would indicate rotation between pulley, and crank nose which would mean clamp loads from bolt have reduced - expect a bang shortly after - As we can see in the case of a few G60s - the crank key was never designed for rotational loads and gets spun off in a second. I think paste of any kind in there is useless. As are diamond washers. What you need is two very flat faces - thats all. Engineers blue, or indeed a black/blue marker can be used to check for flatness. A while back when turning down a pulley I noticed that they were indeed pm(powered metal) as Ed has mentioned. This is for ease and speed of manufacture. It shouldn't be a bad thing in this case, but a poorly made one would not have the same compression resistance as a billet item. Im in no way stating the Vw ones are bad but it can happen. Some pm parts are used in other ways for gears and bearings, whereby density can be reduced and thus the part can absorb oil - in built oiling if you like. Oil-lite bushings or gears for example. Place one of these in a lathe at high rpm and you'll spin the oil out of them even though they appear solid. Premature bearing failure will then result. Thats off topic though. Back to pinning the pulleys, I always used 3mm pins to regain location, as any bigger and your eating into axial pulley/crank interface area real estate. A good quality bolt is the key to keeping the pulley on there. Im surprised no vendor offers a billet pulley and arp bolt actually. Tightening it is no different to tightening any bolt of that caliber and spec. A bolt with a waisted section would be ideal, since the waisted portion introduces the thread loads into the shank/body better. See 5th post down here for more details on shanks, http://www.f1technical.net/forum/viewtopic.php?p=405013&f=4 Brian, edit again, the original vw locking tool further backs up my dowel point, in that it stops the key seeing any torque (it does see some if just the crank is locked). The friction under the head is greater than the friction generated by the threaded portion in the crank nose. Edit one more time for something that nearly took me out on a machine build 2yrs ago and that I just thought of and that is the process called precession. Its late, and Ive been going a long time so Ill leave you with a link, http://en.wikipedia.org/wiki/Precession_(mechanical) Greater loads on the G60s due to higher belt tension too, plus as stated on high tune, greater torsional vibrations/harmonics.
Brian I have picked out the main points from your contribution. Thanks again. I understand the surfaces have to be flat and have been advised to creating a surface match, hence the idea about lapping in the surfaces with course valve compound. As in a working poppet valve this is not left on the surface. I knew the dowels are for locating. If the cog/crank drive gear is new however your timing shift on a 16v, as I have stated is worked out at 0.5+/- degree cam advance. My experiments show there is very little effect on engine torque with this timing tolerance and with a VW tool as you have pointed out to tighten the assembly, this would prove dowelling is not required to maintain crank cam phasing on cogs that are still within keyway tolerance. The other point on the compression resistance on the sintered cog are interesting and one I did not think of as opposed to a billet job. I suspect the use of sintered cogs, which are used widely in Automotive industry would be cost and the fact that the compression resistance would passed all DV work for it's release. I suspect the cogs would come from a specialist supplier to the OEM who would have such testing data. I think we can summarise this thread for the 16v engine ( plus 8v and 20v). To tighten the damper bolt always achieve maximum clamping force using the factory procedure 90Nm + a 1/4 turn. Use a locking tool similar to VW3099. NB (3- 4mm Dowels can be used for positioning but are not necessary in the case of cogs that have key ways with in width tolerance) Following this procedure will ensure your the cog is clamped squarely on the crank nose and returns reliable service over many cycles of use. Thanks to all who posted in this thread. Regards Eddie.
Excellent thread. I'm using Loctite also.... (not wishing to question anything said above, but that's my opinion) Jon
Brilliant thread. Thanks for all the info. Regarding the 8v/16v torque spec difference in the Haynes manual, 8v bolts were of a different design once and were longer and had a separate washer with them. The 16v had an all in one bolt. The interweb will have you believe the early 8v bolts were non stretch and the 16v bolts were stretch items. I don't really know. These were both superseded by a revised all in one (12 sided head bolt with built in washer etc) according to VW as I tried to order the early parts once. Gurds Gurds
you see so many engine failiers with this bolt , in my opinion its mostly when muppet garages remove it for no reason to do cambelt change .then not locked and tightened properly when I am building a engine , I jam the crank with blocks of wood aganist the block, then power bar it up with locktight.and hope your crank seal is good . you can also jam the clutch fly wheel aganist the box bell housing . on some gearboxs.
Ed, a valve can be rotated in order to lap in surfaces/interface. Not sure how it can work in the case of the pulley since the key(when present) will prevent you turning it in order to lap. Brian,
Eddie; thanks for putting in the time and effort to research this interesting subject, and for coming up with a simple improvement that can be made to increase reliability of the assembly.
Missed that Ed - sorry. I think its no harm to blue up and check nose to pulley interface too, Brian,
I eventually got round to fitting my new bolt and was interested in the old torque settings, so I followed the revised procedure (but added locktite) and nipped it up to 90nm, marked it and then tightened it to 200nm and it bearly turned 40deg. So I turned it the rest to complete the 90deg, my torque wrench did not go any higher than 200nm but it would be interesting to find out the torque the 90deg gets too. Anyway, the new VW procedure Eddie illustrates here gives a much better clamping force than the old produces, so definatly follow that and ignore the Haynes
Great thread chaps , just had a quick read after my failure at the weekend. I'll be using 2 dowels when i refit mine . the Torque settings on the T4 Transporter 2.4D Bolt are 331lb/ft which is high compared to the 8v or 16v 4 pot engines
Yes i know , The keyway is slightly damaged on mine so the dowel pin is required to assist the location ( only 1 pin required ) . it will be clamped with great force ( but not too much)
Rough up the mating surfaces between bolt face, cog and crank nose( if possible ) to help the clamping. Torque up properly maybe using the tools suggested in this post Else it will come loose again!
