Clutch Help

January 11, 2008 3:54 PM

Home mechanic question: changing a clutch. I'm changing the clutch in my wife's 1996 Jetta. I've almost gotten the transaxle off, but it's just barely hanging onto the engine. How do I get it off? A few more related questions inside-- any mechanics familiar with changing clutches, please help.

The clutch went out on my wife's 1996 manual-transmission Jetta, and I've been changing it whenever I have time over the last few weekends. I've been taking my time familiarizing myself with it, and I've finally detached the manual transaxle from the engine. That's great, since the clutch is right in there once I pull off the transaxle. There's only one problem.

A little bit of metal, what the manual (I've got the Haynes) calls the "right driveaxle flange," where the driveaxle attaches to the transaxle, hangs over the edge of the large round edge of metal on the engine where the transaxle meets it, and it won't come off of the engine. I can't coax it off with any amount of finagling; it's really on there, and, unless I put a quarter-inch dent in it, it won't come off. Was I supposed to remove it? If so, how in heck do I do that?

Aside from that problem: do you have any suggestions for after I put this all together? I'm thinking of having the flywheel ground, but my mechanic (who I don't altogether trust) says that that's a waste of time and money, and that I should just sand it lightly with some sandpaper if I do it at all. Should I get it ground anyway? Also, any suggestions for post-install tuning?

Thanks in advance for help.

posted by koeselitz to technology (32 comments total)

To remove the gearbox on one of those, remove both driveshafts, undo the gearbox bolts and remove the gearbox (transaxle).

Here endeth the Haynes lesson....

You don't need to remove the diff output flanges, no. I am assuming you have removed the selector mechanism and all the various connectors and the like, too, and that it is simply physically withdrawing the 'box from the engine that is the struggle.

The best bet is to remove the front engine mount and (with a jack under the engine) let the whole assembly move up or down to give more room between the chassis rails and the gearbox. Also, if you pull the gearbox off a little so that the dowels are disengaged you can rotate the whole gearbox on the clutch shaft until the driveshaft flange can slide past the engine and chassis rails. From memory of a Mk3 Golf and a 2002 Polo (although this is 5 years ago), you have to rotate the back of the gearbox up before you can pull it away from the engine so the driveshaft flange clears. Although being as this is a slightly different car, you could always try rotating it down and seeing when it clears. I do remember it being a bitch to do on your own, though. You will, sadly, be mostly holding the gearbox up on your own at this stage. Get another jack under it unless you can benchlift 30Kg while you are dicking around trying to find the correct orientation...

It is possible, mind you, and no grinding or sanding is required or should even be considered. It is perfectly possible to take the gearbox off without damaging anything, even fingers and paint.

What post install tuning did you have in mind?
posted by Brockles at 5:08 PM on January 11, 2008

It's always tough to do a job like this the first time.

It would be really helpful to know someone who has done it before and have them come over and show you.

Other than that, a really good manual is a good bet. (Haynes manuals can be pretty sketchy.) TThe Bentley Publishers manual seems to be highly regarded.
posted by exphysicist345 at 5:18 PM on January 11, 2008

As exphysicist345 says, the Bentley manuals are really good. Haynes are next to useless. Sorry, no specific expertise to offer for your Jetta, but the auto forum at somethingawful (fee rqd to join) is very useful for quick, accurate info on jobs like that.
posted by anadem at 5:37 PM on January 11, 2008

Brockles: The best bet is to remove the front engine mount and (with a jack under the engine) let the whole assembly move up or down to give more room between the chassis rails and the gearbox.

I've done that. Engine jacked, assembly loose... but...

"Also, if you pull the gearbox off a little so that the dowels are disengaged you can rotate the whole gearbox on the clutch shaft until the driveshaft flange can slide past the engine and chassis rails. From memory of a Mk3 Golf and a 2002 Polo (although this is 5 years ago), you have to rotate the back of the gearbox up before you can pull it away from the engine so the driveshaft flange clears. Although being as this is a slightly different car, you could always try rotating it down and seeing when it clears."

Yeah, it seems like the whole thing needs to rotate, but not up-- on this, it seems like it needs to rotate back, toward the driver. And it just hits one of the suspension thingies when it does that. I'm going to look at it tonight and see if that thingie is removable.

I do remember it being a bitch to do on your own, though. You will, sadly, be mostly holding the gearbox up on your own at this stage. Get another jack under it unless you can benchlift 30Kg while you are dicking around trying to find the correct orientation...

It is indeed very obnoxious. But I got a good tip from my mechanic friend-- a jerry-rigged 'engine lift' in the form of ropes strung across two-by-fours laid across the open engine compartment. Seems to work well, and much easier to jiggle and swing around than it seemed to be when I just had the tranny jacked up, even with my rolling jack. When I finish getting it off, I'll jack it, remove the ropes, and drop it out.

exphysicist345: It's always tough to do a job like this the first time.

It would be really helpful to know someone who has done it before and have them come over and show you.

Were that that were feasible. But if I don't manage it this weekend, I'll be dragging Klaus (that hapless mechanic friend) the 100 miles up to north Boulder to take a look at it, if I can.

Other than that, a really good manual is a good bet. (Haynes manuals can be pretty sketchy.) TThe Bentley Publishers manual seems to be highly regarded.

Hmm. I've always wanted the Bentley manual, but I've never seen it that cheap! I may be making that purchase. Thanks! (Should've thought to get it from the printers themselves.)

Thanks, Brockles and exphysicist345, for the help. I'll update here on what happens.
posted by koeselitz at 5:43 PM on January 11, 2008

I'm guessing you need to remove this because it's making it difficult to drop the transmission (crossmember or lower subframe in the way?) or because you now need to replace it/the seal. I'm not familiar with VW's, so I can't tell you an easy workaround but I do have a stupid story that could help. I had this exact problem on an Oldsmobile, but I hadn't taken the driveaxle out of the flange (not wanting to replace the boot, next tim you should do the same if at all possible). I beat on it, yanked on it and tried a small crowbar (prying it away from the transmission using the case for leverage is the approved method). Nothing. Well, casting my eyes around the garage, they laid to rest on an old spade (the short shovel kind). Thirty seconds later the flange was hitting the concrete. It just happened to have the perfect combination of length and a thin prying surface to get between the trans and trans end of the flange with plenty of leverage to pop it out easily. A large crowbar may work. If you have trouble with the crowbar you can tap it (the crowbar) with a large (3lb or so usually works for me) hammer.
posted by IronLizard at 5:51 PM on January 11, 2008

Right, should have previewed. You may want to put one or two of the bolts back in the transmission for safety when you do this, btw.
posted by IronLizard at 5:53 PM on January 11, 2008

For reference, Ironlizard sounds like he is describing a gearbox that it stuck on teh dowels. It may (being an Oldsmobile) have even been a steel gearbox.

Don't do this on an aluminium casing such as those in a VW. You will royally fuck something up.

This is more a matter of clearance than anything else.

Koeslitz:

Maybe you can take some pictures? Theonly removable thing in the area I think you are describing is the lower wishbone (or control arm as it can be called). If this is in the way, it can by all means be removed, but I've not had to on a VW or any other front wheel drive car before. But, as I say, my latest experience is with 2002 model year cars.

For reference, I have taken a very large amount of fwd gearboxes out, and a significant number have been from VW's.

Pictures! Pointing to the hitty bits! I even checked your profile as if you'd have been anywhere near Toronto I'd have come and helped. Must have been catching me in a benevolent moment. Fortunately for me, you live chuffing miles away...
posted by Brockles at 5:59 PM on January 11, 2008

Does this flange look anything like this? If so, nevermind the bit about the boot, but the same prying technique should apply. They're held in place by a snap ring.
posted by IronLizard at 6:00 PM on January 11, 2008

No, Brockles, it was aluminum. It's also what the manual recommends.
posted by IronLizard at 6:03 PM on January 11, 2008

IronLizard: No. Already removed those. In fact, what I'm trying to get off is the piece one of those was connected to.

(And, for reference, it took me weeks to figure out that XZN bolts were holding them on.)

Will take pictures tomorrow afternoon, if I can get any good ones. And, though the man in me would love to smash it out, and I'd contemplated it, I will hold off at least for a while on IronLizard's crowbar suggestion.

Thanks, all.
posted by koeselitz at 9:39 PM on January 11, 2008

Those look like the driveaxles themselves. (If the parts closest to the camera are the ones that the wheels fit onto, then yes.) What I'm trying to get off is the part they connect to, the flange on the transaxle itself that they connect to with those six bolts.
posted by koeselitz at 9:40 PM on January 11, 2008

and I've gotten it past the dowels, too.
posted by koeselitz at 9:41 PM on January 11, 2008

The photo is of this particular part.
posted by IronLizard at 10:54 PM on January 11, 2008

It plugs directly into the trans. Also, if this is anything like a Nissan, stuck a wooden dowel in the resulting hole to prevent the gears dropping down into the transmission case while the thing is being wrestled with. Not fatal, but annoying.
posted by IronLizard at 10:55 PM on January 11, 2008

This is another angle, with both flanges.
posted by IronLizard at 11:00 PM on January 11, 2008

That's an awesome site, IronLizard! I have some fun reading for later today, if I have time...

The way the page is set up, the links you gave didn't work to where you meant them to, but in this comparison of her old and new transmissions, you can see the flanges where the driveaxles connect to the engine. And you can see pretty well how one flange hangs over the edge of where the engine is (when it's next to the transaxle) and could get caught.
posted by koeselitz at 5:50 AM on January 12, 2008

(I should say that that lower tranny looks precisely like mine.)
posted by koeselitz at 5:51 AM on January 12, 2008

Yeah, and there should be no need at all to remove those flanges to take off the gearbox - they are the differential output to driveshaft/axle flanges. Rotating the gearbox relative to the engine should be more than enough to remove the gearbox (transmission).
posted by Brockles at 10:49 AM on January 12, 2008

Brockles: I think I've figured out what the problem is. I'd removed the right (passenger-side) driveaxle, but, though I'd removed the wheel and it's hanging loose inside, and though I removed all six bolts around it, the left (driver-side, away from the engine) driveaxle didn't come off, and still won't. Looking at it, it seems like that's what's banging against a cylindrical thing inside the engine compartment. Is there some trick to get that left driveaxle off? Is it just on there because of wear-- should I just keep jerking on it to get it to dislodge?

I'll poke around a bit and come back. Thanks for all this help.
posted by koeselitz at 11:03 AM on January 12, 2008

... almost forgot, I promised a picture. Here is a pretty good picture of where I think the problem is.
posted by koeselitz at 11:16 AM on January 12, 2008

One clarification:

Brockles: It is possible, mind you, and no grinding or sanding is required or should even be considered. It is perfectly possible to take the gearbox off without damaging anything, even fingers and paint.

I won't consider grinding or sanding to get the gearbox off, but when I'm changing the clutch, and I'm putting in a new one, is it necessary/recommended to take the flywheel to a shop and have them grind it (with special attachments that they say they have for clutch flywheels)? Or, as my mech says, is that a bad idea and a waste of money?
posted by koeselitz at 11:20 AM on January 12, 2008

Success!
posted by koeselitz at 12:00 PM on January 12, 2008

Can I just say that "flange" is my favourite word and I have been truly spoilt by this thread.
posted by hmca at 12:26 PM on January 12, 2008 [1 favorite]

hmca: I am an engineer, and when I was designing engine bits and bracketry, my fellow designers and I used to have competitions to see how many times the words 'flange' and (another wonderful word) 'gusset' could be used in discussing how we woukd make it...

Ah, good (geeky) times...

I won't consider grinding or sanding to get the gearbox off, but when I'm changing the clutch, and I'm putting in a new one, is it necessary/recommended to take the flywheel to a shop and have them grind it

Good lord, no. Total waste of time. Especially on a car that new. If it was a pile of crap that you were restoring, then yes, I'd have the rust cleaned off, but it is beyond unlikely that there is anything requiring of attention on the flywheel. The clutch just needs replacing, that's all. I've never had a flywheel ground or otherwise attended to - even in the 1970 Triumph Stag that I was involved with putting back on the road after 5 years sat in a barn. Just changed the clutch and went. It has been running fine for over ten years with the same, untouched flywheel. I don't think it even has had clutch change in the meantime.

Is it just on there because of wear-- should I just keep jerking on it to get it to dislodge?>

Yes. The driveshaft needs to be dislodged from the output flange. If the outer part of the flange (where the bolts are) is stuck against the flange, you can safely hit the side of that with a hammer (or hammer and long bar if space is tight) until it comes off as long as all 6 bolts are out. If the outer part is loose, but you can't get the driveshaft away from the flange, you may need to take off the lower arm of that side wheel to allow the wheel/driveshaft assembly to be withdrawn from the diff flange. Once it is back far enough, it will swing down and be out of the way for you to remove the box unhindered.
posted by Brockles at 12:57 PM on January 12, 2008

I see you've done it, but the rest of the stuff is relevant.
posted by Brockles at 12:59 PM on January 12, 2008

Having the flywheel ground or not really depends on a couple of factors. If it's developed large ridges and irregularities or 'hot spots' where the metal has changed color it's a very good idea (and it's only 15$ around here). The reason for this is much like your brakes and the same reason you have your rotors turned as part of a brake job. Those ridges and irregularities can cause accelerated clutch wear and the hotspots are now weak points which can develop cracks that spread through the rest of the flywheel (this is less likely, but the accelerated wear should give you pause unless you enjoy doing this more often than need be). The other is how flat the surface is radially. A 'warped' flywheel may not be apparent for a while yet, but will eventually make engagement very rough/jerky. No fun.

Yes those flanges were what I suggested using had used the shovel on. Most front wheel drive vehicles (I see yours is AWD) have those as part of the driveaxle itself. No bolts, it just flares into a cup that contains the bearings. Once they've aged a bit, they become very difficult to remove and the large screwdriver/prybar suggested in the manual isn't enough. There's no danger of breaking the transmission case or even damaging it unless the edge of your prying device happens to be sharp and the sharp part is pressed against the case when you whack it with the hammer. You would almost have to be trying to break it.
posted by IronLizard at 3:22 PM on January 12, 2008

Yes those flanges were what I suggested using had used the shovel on.

Ah, I thought you were saying to pry the gearbox off the engine with it!

Most front wheel drive vehicles (I see yours is AWD) have those as part of the driveaxle itself.

I've never seen a front wheel drive car without a driveshaft that bolts to an output flange on the gearbox. The enclosed end is (as pictured) always on the outboard end. Is this a US car thing? I've seen examples of significant numbers of European and Japanese cars and they are all the same. The only time I have seen one piece Diff output/driveshaft housings has been in race cars. The outboard end is then a bolt on flange.
posted by Brockles at 3:53 PM on January 12, 2008

My Olds 88 and Nissan Pulsar are both like that. The 280z has the flanges, but it's RWD with that style of axle.
posted by IronLizard at 4:10 PM on January 12, 2008

Interesting. I've done some digging, and it seems you're right. A sleeve type arrangement on the inside CV joint. Odd (to me).

However, I am pretty confident in my assessment that no VW driveshafts are like that. I've changed around a hundred and sold many more... (i used to be involved in the VW rallying scene in the UK - driveshaft were common failures) And for future reference, the style that you have seen are (in my experience) not at all 'the norm'. Worth remembering, I think, should you end up heaving on the wrong sort of transmission. The output flanges on a VW are held on by a (big) nut in the middle of the flange into a stud in the gearbox...

You'd be there a while with your shovel, methinks... ;)
posted by Brockles at 4:42 PM on January 12, 2008

Thanks to all. I'm now staring at the clutch, which is a good feeling after all these weeks.

Of course, the very first thing I find is male XZN (Triple Square) bolts. Back to the store again tomorrow for another tool, I guess. The best thing about these projects is that at the end of it I can look at all the cool implements I've obtained during the project.

Brockles: Good lord, no. Total waste of time. Especially on a car that new. If it was a pile of crap that you were restoring, then yes, I'd have the rust cleaned off, but it is beyond unlikely that there is anything requiring of attention on the flywheel. The clutch just needs replacing, that's all. I've never had a flywheel ground or otherwise attended to - even in the 1970 Triumph Stag that I was involved with putting back on the road after 5 years sat in a barn. Just changed the clutch and went. It has been running fine for over ten years with the same, untouched flywheel. I don't think it even has had clutch change in the meantime.

Ah. Thought so. My mechanic screwed up his face ten different ways when I told him the shop I'd been planning to buy the clutch from would only warrant the piece if I let them grind the flywheel. (And then he got me one wholesale, so that's a good thing.) The car only has 100,000 miles at this point-- it's a wonder to me that the clutch went, but we just bought it six months ago from a somewhat odd fellow who did oil changes at a VW dealership, so I have no idea what awful things it's been through. Won't need to grind it, though, and that's a few bucks saved. Thanks.

You guys are great. I'll let you all know what happens tomorrow.
posted by koeselitz at 5:26 PM on January 12, 2008

The output flanges on a VW are held on by a (big) nut in the middle of the flange into a stud in the gearbox...

I did see a picture of one of those stripped whist looking for good images to explain myself. I had (perhaps incorrectly) assumed that he'd already removed the nut.

The best thing about these projects is that at the end of it I can look at all the cool implements I've obtained during the project.

I have a huge number of odds and ends that I may never end up using again from things just like this :)
posted by IronLizard at 5:45 PM on January 12, 2008

IronLizard (For reference): The nut is in the middle of the flange (on the same centreline with the driveshaft and the axle of rotation of the differential) so he couldn't have accessed it if the driveshaft was still in position. Hence my conviction.

As for special tools, I assume the little spline key that you used to remove the driveshaft bolts with is the same? If it is, rest assured it doesn't fiat a damn thing else but VW driveshaft bolts. I've tried...

It gets worse when you start to make your own special widgets and tools for various jobs. I hate to think of the cost of shipping all my tools over to Canada from the UK, when quarter of them are little machined and welded bits of steel and aluminium for one off jobs on obscure cars I'll probably never see again. Funny how hard it is to part with them, mind you.
posted by Brockles at 7:55 PM on January 12, 2008