Saturday, December 30, 2006

VW - TULZ Part Ten

TULZ – Part Ten

FRONT END MAINTENANCE & ALIGNMENT

The steering and front suspension on older Volkswagens needs a lot of attention to keep it working properly, reflecting the 1930's origin of the design. In keeping with the design philosophies of that era the steering and suspension systems are overbuilt by modern-day standards. Although it takes more work to keep these antique vehicles running, the tasks are relatively simple. Designed to be overhauled with a minimum of tooling, the robust nature of the components makes it possible to keep these antiques safely on the road virtually forever.

Unfortunately, the above does not apply to the Super beetle. I've found their MacPherson strut front ends to be less robust than ball joints and down right fragile compared to king pins, making the Super unsuitable for the kind of traveling I do. The poor suspension is made even worse by the steering system used on the '70 through '74 models, a overly complex design that Volkswagen abandoned in favor of the later rack & pinion system.

(So how does the Mexican-built beetle - - with it’s MacPherson-strut front-end - - manage to hold up so well? Crawl under and take a look. The Mexican-built front-end has additional re-enforcement plates not found on the hammer-head chassis from Germany.)

In the automotive world the last person to work on a vehicle is often held liable for what happens next, even if it happens to a component they did NOT work on. Do a tune up and get sued because the kid runs off the road? Sounds crazy but it can happen. This is clearly unfair but so is a great deal of automotive consumer legislation. The question of liability causes me to avoid working on Super Beetles or any Volkswagen with a modified suspension system. My comments in this article, indeed, for the entire series of TULZ articles, are addressed mostly toward earlier model stock Volkswagens.

Whatever your vehicle, before you can maintain its front end you need to understand how it works. You should be able to make a sketch, either schematic or pictorial, depicting all of the components in your front end and know their names. All of the manuals contain this information in one form or another but I think the novice will find the 'Idiot' book to be the most helpful for this task.

Now let's go play. But before we do, note that I use a different sequence of diagnostic checks than does the 'Idiot' book. Try it both ways then decide for yourself.

Jack up the front end, pop off the grease caps on the front wheels, take the slack out of the bearings then jack up the front end and SHAKE THE WHEEL. You're looking for play; for looseness. Try to lift the wheel up & down. Then try to rock it back & forth. Finally, grab it at 6 & 12 and try to rock the wheel in & out. A tiny bit of up & down is okay. Anything else sez repair or adjustment is needed. No play? Then skip on down to the steering check.

When you feel looseness the next step is to figure out WHAT needs to be repaired. As a general rule, any up & down or in & out play indicates wear in the SUSPENSION; in your ball joints or king pins. Any back & forth movement indicates wear in your STEERING. (Super beetles are a special case. In & out movement may indicate wear in your control-arm bushings.)

On old bugs & buses if you feel a lot of in & out play you may need only to adjust your link pins. Link pin adjustment is a simple chore, something you're supposed to do every other oil change (No, not 'Every 6000 miles.') Read the fine print. There's a whole list of things that require you to change the oil more often. The list of exceptions – driving in dusty conditions, on unpaved roads and so forth – also applies to your other periodic maintenance requirements. So use the oil change interval as a guide. And every other oil change, WHATEVER THAT INTERVAL MAY BE, lube and adjust your link pins.

King-pin spindles use bushings for the king pin and either bushings or needle bearings for the link pins, depending on the model year & vehicle type. Rebuilding king pins consists of removing the spindle from the trailing arms, taking the spindle apart, pressing out the old bushings, pressing in new ones then reaming them to fit the new king pin. The Haynes manual does an especially good job with king pins.

The new king pin and bushings come as a kit of parts but if you're a machinist you can make your own. The link pins also come as a kit except on later models there's no reaming; they come with needle bearings instead of bushings and the needle bearings are already the proper fit. See the real shop manual for your particular ride. A number of fellows who have rebuilt their front ends have described doing so in messages you'll find in the various archives on the Internet.

Newer buses & bugs don't got link pins. Them got ball joints. That's where you'll find most of your up & down play. See the manuals for the specs but anything more than a tad is bad.

You can keep a link-pin front end running just about forever but once a ball joint goes bad you got a major headache. Oh, you can do them. In fact, they're easier to do than rebuilding a link-pin spindle. But you need a hydraulic press and some fixtures. And you gotta pretty much dismantle the front end to get at them, which can take additional special tools. The reason for the additional dismantling is because the ball-joints are installed on the trailing arms, meaning you've got to remove the trailing arms in order to replace the ball joints. Removing the trailing arms is a no-brainer but the stabilizer bar is clamped to the lower trailing arms and new, replacement clamps are no longer available. If you're careful dismantling the old clamps they can be reused but a better option is to use Sway-A-Way bolted clamps. Cost is about thirty bucks for all four. I don't know if they've got them for buses.

Muir and a lot of others say ball joints should only be replaced by a VW dealer. That may have been valid back when John was alive but today such advice is little more than a bad joke. Nowadays the typical Volkswagen dealer wants nothing to do with you and your antique ride. They don't carry your ball joints, they don't have the tools to replace them and their mechanics are not familiar with your vehicle.

If you take your veedub to the dealer to have the ball joints replaced, odds are they will order rebuilt trailing arms from an after-market supplier who specializes in VW front end components. The trailing arms would arrive with the ball joints already installed, reducing the repair job to nothing more than dismantling and reassembly, a task anyone can do. Indeed, you can do exactly the same, saving yourself some serious bucks along the way. Check the ads in the magazines for outfits offering rebuilt trailing arms.

Buying rebuilt trailing arms is probably the most common method of repairing front ends but there's really no reason you can't do the entire job yourself. Ball joints are inexpensive, which is good because they don't last very long. No grease nipple. 'Lifetime' part. An hydraulic press makes their replacement easier but a twenty-ton bottle jack is strong enough to pop the ball joints out of the arms and to press new ones back in, assuming you have a suitable pressing frame and the necessary fixtures to support the trailing arms while you do the pressing. You can make the required fixtures from sections of steel pipe of the proper diameter. The sections of pipe have to be notched & shaped to accept the trailing arms (you need a left & right fixture for each). The notching is done with an angle grinder and the trailing arms themselves serve as the pattern. I was out of Prussian blue so I begged a tube of lipstick from my wife to use as spotting compound. (You press the parts together then grind off the high spots, as shown by where the lipstick transfers from the trailing arm to the fixture.)

The pressing frame is just a rectangle about two feet high by a foot wide fabricated from sturdy (2 x 4 x 1/4) steel 'C' section, welded or bolted together at the corners with gussets. (I say 'about' because it has to be sized to accommodate the height of the fixtures you make and the particular jack you use.) In use, you position the old ball joint atop a short section of pipe that serves as the 'drop space' to receive the ball joint when you press it out, then put the pipe-section driver on the bottom of the ball joint and seat the hydraulic jack atop that, extending the jack until it contacts top of the frame. Then just pump the jack. The old ball joint will be pressed out of the trailing arm. Installing the new ball joints calls for a bit more care. There is an alignment notch that must be taken into consideration, your fixtures must be a very nice fit and the trailing arm needs to be propped up to keep everything aligned. It sounds sorta hay-wired but it works okay. The first time I did it, it took about four hours to make the fixtures and another hour to replace the four ball joints.

SLOPPY STEERING

Now let's check the steering. Start by lowering the vehicle. Your front wheel bearings are still tight (ie, all the play has been taken out; see the previous procedure). Your ride is parked, wheels on the ground, engine off, e-brake set. Reach in through the driver's side window and use ONE FINGER to turn the steering wheel.

How far did it go before you felt resistance?

That's too far :-)

It should only go about ONE INCH. Time to go find your partner, because diagnosis of steering problems takes two people, one to move the steering wheel, the other to figure out where the lost motion is going.

Your steering gets sloppy because of accumulated wear, mostly in the steering gearbox. See that little adjusting screw on the steering box? LEAVE IT THE HELL ALONE. That governs engagement of the roller with the worm and odds are, it's okay. (The roller adjusting screw wanders around from model to model. It's on the top of the steering gear box in bugs, on the side for buses.)

There are three main places for wear to accumulate inside the steering gearbox. Two of them are on the roller, the other is axial play in the worm, which accumulates wear more rapidly than the others due to the gear ratio between them. But in recent years an entirely new problem has cropped up, one that is due entirely to age and as such, is not covered in any of the manuals.

On early bugs & Ghias the steering gear is connected to the steering wheel through a compliant coupling. Before you start adjusting anything, inspect the coupling. That takes two people, one to move the steering wheel while you inspect the coupling. What you're looking for is any deterioration of the rubber puck in the universal joint. Also inspect for any motion on one side of the coupling that does NOT get transmitted to the other side.

Make sense? The coupling is a rubber disk. Two bolts hold it to the steering wheel shaft, another two hold it to the steering gearbox. If the coupling is bad you end up with a lot of play in your steering wheel even though there is absolutely nothing wrong with your tie-rod ends or steering gear.

So check it. Look for axial motion in the gear box shaft as the steering wheel is turned. (If the steering joint looks suspicious, pull the fuel tank and examine it more closely.) (Note: Axial means in & out; motion along the axis of the part. Radial motion means movement ACROSS the axis of the part; along the radius of the part.)

Early VW steering uses a worm & roller arrangement and is meant to be periodically adjusted to accommodate wear. The worm gear is on the end of the shaft to the steering wheel; when you turn the steering wheel you rotate the worm gear. The worm gear engages a roller gear that gets pushed from side to side as the worm turns. The side-to-side push is what's used to move the wheels.

Most of the slop in your steering gear is due to wear on the shim at the upper end of the worm gear and is adjusted by loosening the large lock- ring on the bottom of the steering gear box then turning the deep multi- point socket-type adjusting nut. Odds are, you don't have the wrench for the locking ring nor the socket for the adjuster. But you can make both of them.

To make a wrench, draw the shape of the nut onto a suitable piece of steel then use the best available means to create the hole. The usual procedure is to drill a series of small holes then hold the blank in a vise and use a chisel to 'connect' the drilled holes. Once you've made the opening you simply file the hole to fit. Since you probably will be using mild steel, make a box-end rather than an open-end wrench.

The internal multi-point socket can be made using any commonly available METAL-FILLED epoxy. To keep the epoxy from sticking to the nut, spray the cavity with silicone lubricant. The keep the epoxy from oozing out before it cures, use tape to secure waxed paper & cardboard over the epoxy. To provide a means of turning the newly molded socket, you may insert a large-diameter coupling nut into the epoxy or fabricate a more elaborate matrix by welding a nut to a steel plate ground to almost fit the socket. In this latter case the metal-filled epoxy must bond to the matrix so provide plenty of keying surfaces and keep the matrix perfectly clean.

The adjustment is straight forward: Take up the slack until you have the spec'd one-inch of play measured at the steering wheel. There is some interaction with the roller gear so you may need to make a SMALL adjustment there as well. But be careful. You can force the roller into such tight engagement with the worm that it will cause the steering to bind. You'll discover this when you go around a corner… and keep right on turning, up over the sidewalk, through the drugstore and back out onto the street, round-and-round you go. It can ruin your whole day.

The Haynes manual (#159) does an especially good job of illustrating the steering gearbox adjustment procedure.

Lost motion in your tie-rod ends usually appears as the rod-end being pushed up or down or leaning to one side instead of smoothly transmitting the push or pull. If you grasp the suspect rod-end in your fist and squeeze tight while your partner moves the steering wheel, the play in the rod-end will be clearly evident.

Replacing tie rod ends are a no-brainer. You unscrew the old ones, screw in the new ones. But there are a couple of Gotchas! The first is how to get those suckers apart and here again, you need the proper tools. One tool you DON'T want to use is the beloved 'pickle-fork'. (You'll end up bending a tie-rod.)

The proper tool for popping loose ball joints and tie-rod ends is a fulcrum-type press. You slide it on the joint, turn the big bolt then give the SIDE of the eye a sharp rap with a SMALL hammer. The shock causes the stressed parts to pop apart like magic. You loosen the nut but leave it on the fitting to protect the thread.

Nowadays its getting hard to find just the tie-rod ends. They want to sell you the whole tie-rod. If that's all you can get, fine. They've also stopped putting Zerks on the tie-rod ends. Instead, they are 'Lifetime' parts, meaning they'll only last about half as long as they used to. Progress, eh? :-)

SWING ARM PROBLEMS

This applies only to Transporters.

In the bus, the steering gearbox is in front of the torsion bar housings, what most folks call the front axle assembly (it's actually part of the front suspension system). But the steering tie-rods are BEHIND the axle. To transfer the motion from the steering gear to the wheels Volkswagen was forced to use a different arrangement than they used on the sedans and Ghias.

The swing arm pivots on a pin supported by bushings. The pivot is highly stressed and sees a lot of motion, resulting in fairly rapid wear of the bushings. This wear is a major cause of sloppy steering in buses.

When the wear is minor you'll see a slight cocking of the swing arm as the steering wheel is turned. That's all it takes to totally screw things up.

When the wear is extreme you can actually rattle the swing arm with your hand. IF you find one this bad, DON'T DRIVE IT.

The repair is similar to doing your king pins in that you remove the old bushings, press in new ones, ream them to size and install a new pivot pin. Read all of the manuals then decide how you want to tackle the task. You'll probably end up following the procedure in the 'Idiot' book. I prefer to pull the whole front axle and simply swap it, partly because I've got a spare but mostly because I do better work standing up than lying down

FRONT END ALIGNMENT

After working on your front end you need to check the alignment and you'll probably hear more bullshit – and waste more money – on this task than any other of your many periodic maintenance requirements.

The first Myth and money-waster is that the work is so esoteric and of such precision that it can only be done by an alignment shop. Not true; not a bit of it.

The truth is, of the four factors effecting your alignment (caster, camber, toe angle and king-pin inclination), two of them (caster and king pin inclination angle [the term applies to all vehicles, even those without king-pins]) are not adjustable in the normal sense; they are built-in to the Volkswagen front axle assembly and unless you've suffered collision damage or modified your suspension, caster and king-pin inclination are fixed; there is no adjustment, no matter what the fellow at the alignment shop has told you.

Of the remaining two factors, you set the camber when you rebuild your king pins or replace your ball-joints. With king pins, the camber angle is set using shims and all of the manuals give the appropriate shim-stack data. All you need to do is make sure the shims are NEW (ie, of the proper thickness) and check the result with a protractor to insure camber is correct when you are done.

With ball joints, camber is adjusted by turning the eccentric barrel on the spindle in which the upper ball joint pin is mounted. Here again, you need a protractor of some sort. The spec for camber is about half a degree (check your manual). You can buy inexpensive (ie, about $30) wheel-alignment protractors that are accurate to about one-quarter of a degree (J. C. Whitney carries them) or you can make your own using plywood and a plumb-bob that is accurate to about three seconds of arc [ie, about one-twentieth of a degree] (see the article titled 'The Camber Checker Thingee' in the archives of the Type 2 Mailing List [www.type2.com] ).

That leaves only your toe angle.

Your toe-angle will change as wear accumulates in your front end and steering. This is normal. So you check it periodically. This too is normal. I do it every other oil change because on my old bus, that's when I adjust my link pins. Any time you adjust your link pins you will probably find your toe angle has changed slightly. So you adjust it.

To adjust your toe angle you measure the difference between the front and rear edges of the rims of your front wheels. The wheels should be slightly pigeon-toed. With fifteen inch rims, the front edges should be about an eighth of an inch closer together than the back edges. To make it so you simply loosen a tie rod and turn it. Making the tie rod shorter will pull the rear edges IN forcing the front edges OUT. Turning the tie rod in the opposite direction (ie, making it LONGER) will have the opposite effect.

Read the toe-in adjustment procedure in the 'Idiot' book. It's as clearly written as most.

Are you all done? Then adjust your front wheel bearings, put the grease covers back on and safety the speedo cable. Since the wheels are in the air you might as well adjust the brakes, too.

-Bob Hoover
-10 May 2K

1 comment:

DAN VOCKINS said...

Hi Bob, just read your advice on vw suspension. Very clear and concise, thanks