No. 1 reason "we" failed cars at Tech Inspection, Loose front wheel bearings......... Options

[Carrera916]

Yup Demick and Slits are correct....

The heat expansion is the issue that there has to be a very slight rocking movement...not zero movement.....as the bearings heats up, it expands and the rocking movement will dimish a bit...that's where you need it for the lubrication to slither around....

As for Dave's comment about using the screwdriver, yes, its important that you move the washer with the tip of the screwdriver on your own, ...do not use the rim of the hub as a leverage...you need to feel the slight friction of moving the washer with a tad of push or pull, then its done....pin it!

That's how its done with taper bearings....

j

[Carrera916]

I tightened mine before the event and there is still slight clunk, I am probably on the verge of overtightened now even. The bearings looked great but I don't know how old they are.

jeff...

you might want to pull the bearings out again and degrease everything, plus the race on the hub...check the surface of the race, if it's pitted or has a dark groove on it, replace them period....ditto for the roller bearings' surface...

it's no fun to drive the car and find yourself with a seized front wheel in the middle of your driving....

it's actually cheaper to replace the whole thing now and start maintain from there as part of your car care check list....

j

[Demick]

...you need to feel the slight friction of moving the washer with a tad of push or pull, then its done....pin it!

Yes, but it is not slight friction, it is quite a lot of friction. As Dave said, you should just be able to slide the washer back and forth without leverage.

Demick

[SLITS]

How 'bout turning the nut till tight (not with a 3' cheater bar either) and then backing off about 1/16 to 1/8 turn (one or two flats)? Yeh, I know it's not metric - but then I'm not politically correct either.

[lapuwali]

I just replaced both sets of front wheel bearings on my car, as they were noisy. I used the same procedure I've used on Alfas for years, which have a very similar front hub design:

After installing the races and refitting the hub and outer bearing, washer, and the pinchnut, I install one lug bolt and use a big wrench to tighten the pinchnut as tight as I can get it. The shaft of the wrench rests on the one lugbolt to ensure the hub is turning while I do this. This seats the races completely w/o risking the bearing rollers "dimpling" the races.

Loosen the pinchnut until I can just feel axial play in the hub. Now very slowly tighten until I can't feel any axial play (pushing/pulling on the whole hub/rotor). With the brake pads out and/or the caliper removed, the rotor should continue to spin for a revolution or two after I spin it by hand.

The other mistake I see people making (including the PO of my car) is WAY TOO MUCH GREASE. You just need enough grease to pack the roller cage. You don't need to fill the hub with the stuff, nor do you need to smear it all over the rollers and races. The rollers are supposed to roll against the races, not skid on a film of grease.

[F4i]

The way I have always done it is this. I tighten it up snug (not blindingly tight) with a wrench to seat everything. Then I back it off half a turn or so (loose). I finish by tightening it by hand. Works every time.

[Dave_Darling]

What are other things that can cause clunking other than the bearings being too loose?

See Mueller's first post. Balljoints, shocks, the "gland nut" on the strut, upper strut bushing rotted away... Probably more possibilities.

--DD

[airsix]

Use an Allen key to loosen the set-screw in the retaining nut--you'll likely have to clean off a bunch of grease to find the set screw.  Use an open-end wrench (forget the size, but it's large!) to tighten the nut until you can just move the washer that's behind it with a screwdriver.

I would make one small edit to that. It's good practice IMHO to loosen the pinch bolt, then tighten the retaining nut while rotating the hub to get it seated well. Tighten the retaining nut to the point that you can feel resistance as you rotate the hub. THEN back off the retaining nut just a hair until you can move the washer (with some light resistance). This insures that the hub is seated properly before you measure the free-play. If you have a loose bearing to start with, just tightening the retaining nut without seating the hub first might not get you where you need to be.

(FYI This is the correct procedure for automobiles. A&P mechanics are taught to take out ALL play, which is the correct procedure for aircraft hubs but not correct for cars, but I'm sure our resident A&P trained 914-nut/WCC-technical-inspector knew that.)

-Ben M.

[silver six]

On a related topic, among some, there appears to be some confusion about the difference between the front wheel bearings' feather weight torque setting and the rear castellated nut's gorrilla torque setting.

A few years ago when I used to do some freelance work on VW's in Oakland I came across a customer complaining that the back end of his Karmann Ghia felt squirrelly. Upon inspection of the rear castellated nuts (36mm nuts, if I remember right), after taking out the cotter pin, I was able to remove the nuts by hand. Mind you these nuts hold the rear wheels and on. The Ghia should have had those nuts torqued to 220 ft/lb, or there abouts. Our 914s have the same set up and similar torque. It was the cotter pins keeping this guy's wheels on. Both nuts were this loose. After I properly torqued the nuts, the owner could not have been happier and said it felt like driving a new car. A car whose wheels were not about to fall off, I suppose.

My theory is that the last person who "tightened" these nuts before me, thought the procedure was similar to the procedure, outlined by DD, for the front wheel bearings. So instead of 220 ft/lb, the nuts were torqued to 8 ft/lb.

A few months ago I checked the torque on my 914 castellated nuts. One was fine, but the other was easily 50 ft/lb or so too loose. Word up.

Douglas

[krk]

It might be good to add the instructions for fixing these things as well -- sort of a "the day before you go to the AX, check these things, and fix them". Just a thought.

kim.

Kim

We did. It was printed in the packet that was mailed to each registrant. It was also printed in the event booklet that came in the goodie bag.

Demick

Hm. Well, I was thinking more about where we go from here -- like, after the WCC/etc, if there is an interestin in seeing more folks to go AX'ing and such. Why not an AX area or an AX list. Certainly I'd be interesting in seeing ideas on better car prep for the sport.

kim.

[J P Stein]

(IMG:style_emoticons/default/agree.gif)

....but last time this was brought up, it was shouted down.....something about dilutung the drivel....as I recall (IMG:style_emoticons/default/biggrin.gif)

[Rob Ways]

I opened the engine bay and the battery was damn near the other side of the engine bay.

This is why we tech cars. I'm glad it worked out without battery acid or major damage.

The cool part is knowing any number of 914 guys come out of the bushes to get your car up and going. Last year, a guy in a 911 had his battery strapped loosely to his spare tire (not tied down). I flunked it. He didn't run.

[Mueller]

Rob, his battery was inspected by me, I even tried to move it with my hand...of course I didn't grab it and try to yank it off of the tray....had I used that method, I'm sure others would have failed or freaked the owners out (IMG:style_emoticons/default/smile.gif)

[Bleyseng]

Time for Britan to weld in a new battery tray. I saw his when we were swapping batteries trying to fix Brads truck. The tray is pretty rusty and a new tray is cheap.
If everything is in good shape you aren't gonna lose a battery out of a 914. Its just most of them are slightly rusty......and weak. Those you can pull the battery out of because of the rust on the backside of the tray where its welded to the wheelhouse.
Britan is running a Optima atleast or else acid would have been everywhere.

Another thing is to tech for stuff that could fly around in the cockpit. The fire extingusher flew out of its holder and landed under the petals when I was driving. It wasn't a problem until I had to hit the brakes at the finishline <_<


Geoff

[Demick]

The fire extingusher flew out of its holder and landed under the petals when I was driving. It wasn't a problem until I had to hit the brakes at the finishline

Fire extinguishers are supposed to be held in place with a metal bracket fastened securely to a metal part of the car. If your extinguisher was using one of those plastic holders, it shouldn't have been in the car for autox.

Demick

[DNHunt]

I was one of the guy Mueller failed. I had been taught to tighten the retaining nut to the point that the hub won't turn then back off a quarter turn (from old Super Beetle days). Wheel bearings are pretty snug this way. However, I didn't check the wheel bearings before I left (oops) so I'm glad Mike pointed it out.

I did have a shimee at 3400-3600 in 5th on the way home. I stopped and checked the front end but couldn't find anything. Both hubs were very warm but not hot to the touch. I'm gonna give the car a rest for awhile then take it apart and check it.

Dave

[richardL]

Fire extinguishers are supposed to be held in place with a metal bracket fastened securely to a metal part of the car.

It is... somehow the strap came undone and that allowed it to move - I intend to make sure it won't happen again. Geoff got to do the shakedown runs on the car and he got to find the 'issues' (IMG:style_emoticons/default/sad.gif)

Richard

[nine14cats]

If your going to auto-x or track the car, you may want to make a tie down that is sturdy. Here's a shot of mine with an aluminum bracket that is fabbed to keep everything in place. I've had my batterey tray break on me as well...makes it tough to start!

Bill P.

[EdwardBlume]

Mine's in the trunk with a welded bracket holding it down. I just got tired of the whole rusted battery tray issue.

[Bruce Allert]

The fire extingusher flew out of its holder and landed under the petals when I was driving. It wasn't a problem until I had to hit the brakes at the finishline (IMG:style_emoticons/default/dry.gif)


Geoff

Hmmmmmmmmm.... sounds similar to the old camera under the gas peddal trick, eh JP? (IMG:style_emoticons/default/laugh.gif)

...........b