Uprated Flywheel Bolts for 16V? This is a topic that's been mentioned by myself and others before. I'm in search of suitable 'uprated' items for my new purchase in the next few weeks. I believe some years ago we discussed the issue as some of the 'higher' revving valvers were having a few failers with the bolts snapping myself included. Wheter it was extra strain being caused by the Quaiffe diff or the high revs who knows but some yeras ago VW Racing developed a solution which I am investigating. ARP don't list uprated bolts but I remember someone, could have been Bill Brockbank, mentioned RS Cosworth bolts may be suitable or are their suppliers of such items in the UK? Wonder what the load is on these ickle blighters? Getting ready for track as soon as I get the car back as I've been out of the loop for years now. Ian
Yes try Bill AKA Badger5 http://www.clubgti.com/forum/showthread.php?t=193557 I have set of those bolts (for 02A/02J based boxes, I can't complain they've not snapped or broke yet!
020 box I assume? Dick Bennett at Mardi Gras used to prep Golfs when he worked at GTI engineering. They had a few clutch centres break, as in: cracked between the 6 holes on the crank. Solution was a spreader plate over the top, ie a big one-piece washer for the 6 all in one. As for the 9 outer bolts: pass. They break with revs, as we know, but I've not tripped over a VWM upgrade.
Cheers Chris....it's the outers that go....wondering if there is a better solution or stronger bolts that could be sourced from a manufacturer.
Part number listed in the Mk2 Golf group A manual for the 9 studs is N 100 720 01 SP. That's not a reference which will turn up anywhere near a VW dealer, but the SP suffix confirms a different to OEM bolt being used. Worth investigating through your contacts and also a call to Mardi Gras would not go amiss. You'd need to speak to Dick Bennett as he is the one who would know. It won't necessarily be definitive on what the works cars used, but it could give what they used as an upgrade. I remember CFJ sheared some a few years ago. Were they new or reused? It doesn't seem to be massively commonplace, that's all. I never had an issue on 8k rpms for eg. Neither did the previous owner's 3 years of R&D etc.
Here you go we had a thread on this at one point. i used head studs washers to space the shanks to fit a O2O pressure plate ARP Crank Studs ARP Studs fitted with head stud washers
IIRC, the peripheral flywheel bolts are M7 x 1.0 pitch. (vagcat won't load)? I guess these are 8.8 Hex bolts? Can someone please confirm? This M7 thread is know as "Third Choice", so is used rarely. I looked for high strength Cap Screws, 12.9, but no one lists M7. I found these if you are wealthy! http://www.tastynuts.com/Products/M7_100 http://www.mettec.com/category/175 From an engineering point of view, the system, used on Mk2s, is quite flexible. The relatively thin wall of the pressure plate will tend to flex, and the 9 bolts are quite small and will only offer a small clamp area, adjacent to where they screw into the pressure plate periphery. Also, the bolts are relatively long, so, due the engine torque generated loads, at the bolt head/flywheel joint face, will tend towards a bending moment in the bolt. One possible solution, might be: Open out the holes in the flywheel to take M8 bolts. Drill out the threads in the pressure plate to suit. Use 12.9 Cap Headed Bolts + K-Nuts or similar. Please feel free to take the pi** out of me if this sounds stupid!
I cannot remember ever seeing anyone bothering to dowel either the flywheel (02A) or the pressure plate (020) to the crank in all the excessive time I have spent on here. This is common practice on most competition engines and I am sure would help eliminate any flywheel to crank, bolt problems. Obviously costs a little machine shop time, but offset that against a crank and engine rebuild it does not amount to much. The early 020 clutches have 2 dowel pins to locate the flywheel onto the pressure plate but the latter ones in mk3 and mk4 (02K box) just use one. Think Geoff Thomas mentioned some kind of modification to the outer M7 bolts similar to what Daved suggests above though in the thread on his mk1.
B6 used to run a dowelled flywheel courtesy of olly elworthy after a missed gear resulted in 6 of the 9 flywheel bolts being bent or sheared.... No issues with the dowelled flywheel and 7800 limit
Mk2 PB - 180,000 miles - 1 Owner (except for the Ba**ards who stole the car and wrecked it) - original clutch - never slipped. I see two 'dowel' pins. Trouble is they are rolled spring steel and quite a loose fit in the pressure plate holes. The flywheel fell off. Not really doing a lot. Proper dowelling would use solid pins, and need a puller to remove. The torque from the engine should be transmitted through these 'dowels' in direct shear. They are such a loose fit that some relative movement would occur. Note the polished areas around the bolt holes = movement. The bolts are so small, and tightened to such a low torque figure, 20 Nm (on a Mk2 8v and 16v engines according to Bentley - not to be confused with any other type of engine - in any other car - and they may well have been 'lubricated' but I don't know what with - so I don't know what the pre-load was) that they can do little more than stop the flywheel falling off! The bolts are probably 12.9, I'm not so sure that anyone bothers to manufacture 12 point bolts in a much lower grade, (a bit more expensive to make compared with a hex head). I did a quick file test, and they are harder than 8.8, but I have lost the feel, so they could be 10.9. Hardly matters though, because, at 20Nm is nothing for just about any grade of bolt to take. Notice the wear on the springs. Probably touching the highest of the three spring retaining fingers?
Some of the flywheel to pressure plate M7 bolts I have got have 10.9 on their heads, but others have nothing, or a manufacturers mark. The shiny "pads" of the flywheel have obviously been moving on the pressure plate a little.
Ta, danster. What I forgot to mention was how easily these bolts loosened. I did not lock the flywheel, but held the starter teeth with my left hand and, used a 9mm cranked ring, radially, across the flywheel outer face.
Fine thread though. Plus the fact you got big dirty hands! They usually need a fair bit of torque to release them when I have taken them out in the past. 100s of times. I will nip out and check 6 flywheels for movement. Maybe some one has done a clutch on the car in the past, even though you think it is original. Maybe miss daved roasted one once and got it fixed on the sly so she did not get in trouble from you.
Just checked six flywheels and there were only two that had very slight signs of movement. This could be down to how hard the cars were driven though, so for the hard chargers on here it is something to consider I suppose.
What big dirty hands? I've only got small hands! Had the car almost from new. It was a Gilder's demo car. So if they changed the clutch, it was in the first few thousand miles of its life! The VW logo is still clear as day on the driven plate. Perhaps the ba**ards who stole it changed the clutch. Good of 'em to put OE VW in. Check the muck inside. It's not been apart for a long time. I've always been light on clutches, so I recon I've not forgotten changing this one! Miss daved roasted her own Mk2 Gti clutch. The only Mk2 Gti we owned that ever needed a clutch. I remember that I was changing her Mk1 Driver clutches week by week.
Found this crack. It has been there a long time, possibly from new. You can see how the push rod has run off centre. The wear on the retaining spring matches the wear on the driven plate springs. The sharp corners at each end of the crack are bad design. They form great stress raisers. They would have been better punching small holes first to relieve stress. Few thoughts on the design of the clutch mechanical system. Refering to sketch below: 1: The cross section shows how the bolt is reatively loose in the flywheel. Any loosness in the bolted joint will allow a lot of movement. 2: Shows that as the rolled dowels are in slots, and are close together, then movement will allow rotation around one of the pins. Not good design. I am working on ideas and will post when ready.
Excellent work there daved. You can see how it was hard to explain in my pms all the profiles without you seeing it first hand. I reckon it should be possible to improve the fit of the two components though.
Working on it. Got some ideas, but need to really get my act together, so's I don't look a bigger ejt than usual!
Pinning the flywheel is not unusual on 4 cylinders. The natural 2nd harmonic is absorbed through the flywheel bolts and onto the flywheel. You cannot get away from or prevent this. It'll always be there no matter what your crank looks like. The only way to add additional absorption for the 2nd harmonic is to use our good old torsional damper but even then it will be only be really effective at a certain rpm range. So ya, pinning is good, may be a bit harder though on the arseways 020 clutch setup mind you. The best material for the dowels would be a good grade steel, case hardened on the outside, but having a ductile core and interference fit, a reamer would be a good idea. Oh and Daved, I love the grid paper, great to see it in todays 'electronic world'. Brian.
