Wheel bearings - 850 Spider

DSpieg

True Classic
Wasn't sure whether to post here or in the "rear-engined Fiats" section, but anyway....Started getting wheel bearing noise on my '71 850 Spider, sounds like the left front. So this weekend I did a quick inspection, removed the left front wheel and grease cap, unstaked the hub nut and loosened it enough to pull the outer bearing out a quarter-inch or so. Cleaned out the 'old' grease (which was only about a year old and looked fine), packed with new grease, adjusted the bearing per the book, then went for a test drive. No difference.

It was harder than expected to find replacement wheel bearings for the car, I finally located a front bearing "complete set" from on of the eBay vendors, and while waiting for those parts to arrive I might do a similar check on the right front.

Looking for any advice from our wise gearheads - what to look for, tips on doing the replacements, whatever. A search here on Xweb turned up much advice for X1/9s (no surprise) but no posts related to the 850, which has a different design for the bearing installation. Also looking for a source of rear wheel bearings in case I need those too, I couldn't find them anywhere except possibly one seller in Germany.
 
The bearings on an 850 are old style conventional.

Remove the old inner seal, remove the old seats, install new seats, install the inner bearing, the seal then apply to the knuckle. Install outer bearing, washer and new nut. Install is the same as a 124 series car (effectively). Just follow the manual’s directions on how to apply preload. Wear some gloves to press grease into the bearing if you don’t have one of those packer cones for your grease gun. (Reminds me I need to buy some grease for mine).

A bad bearing won’t sound better by repacking it.

If you don’t have the manual I can scan the directions for you, I will be going into the office today so it would be an easy thing to do for you.

Maybe someday we can have a Best of 850 if that section of the forum grows... there are some good threads in there, just not the volume of information on the rest of the Xweb.
 
Thanks, Karl, great info, I can take from there :D. Still looking for rear wheel bearing parts; fronts are on order.
 
The rear bearings normally last the life of the car. Which back then wasn’t long...

Seriously though the rears are pretty durable. That said a bearing noise can be difficult to track so it is concievable that a rear one is the one making the noise. Are you looking to replace them just to have it done or or for a real mechanical reason.

Fiat does have an unusual torquing process for their front bearings, you would do well to follow it. New nuts for the spindles in front are in order.
 
Thanks again, Karl. I've had a bit of wobble in the back of the car the entire 10+ years I've owned it, which is why I'm going to at least take a look at the rear bearings (issue unrelated to the recent noise). I was able to find and order rear INNER bearings - I suppose there are OUTER bearings too, or does only the front have both innies and outies? None of my four manuals (Haynes, Chilton, "factory", or Autobooks) provides much detail.

As for the fronts, I did torque them per the book last weekend, and not surprisingly the spot where the nuts ended up to be staked was this same position they had been in previously. I did order new nuts along with the front bearings.
 
MWB is your friend here, they have the parts book for the 850 online. Yes there is an inner and an outer.

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First, what makes you think the noise is bearing related?

The bearings are pretty durable and I've never had a bad one in an 850 or 600 in 5 decades, although when doing a major rebuild, I've replaced them regardless as they don't cost all that much. You could take the bearing, clean the grease out and spin it in your hand and see if it feels rough in any way. And/or use a compressed air gun to spin it fast . Should spin very smoothly in your hand. The bearings aren't hard to find. MWB is a great place to buy quality parts plus their shipping is lightning fast. I've bought lots of parts from Europe but shipping can be very slooow unless you want to pay a lot on a courier.

The left front has a left hand stake nut. Use a new stake nut. From factory manual: Tighten nut to 14.5 ft-lbs while rocking the wheel 4-5 times. Then undo the nut all the way. Tighten to 5.1 ft-lbs. Finally, back nut off 30 degrees and stake in place. If you happened to have a dial indicator, end play should be 0.0010" - 0.0039".

The problem you will have is finding a torque wrench that reads torque in a counter-clockwise direction. Often you will find that a description of one says it works in either direction, but that likely means it only works in reverse fully locked to undo nuts (which you shouldn't do anyway). Also, a click-type torque wrench that will read (with a good accuracy) of 5.1 ft-lbs are expensive. A beam type one that reads in inch-lbs will work but can you trust the accuracy? I looked everywhere for a suitable click-type torque wrench and could not find one at a reasonable price anywhere. It's also not something you'll likely use often either.

I recently rebuilt a set of 850 uprights including new bearings & seals. I used a 3/8" breaker bar like below and measured some weights on a postal scale and hung them from the end of bar and made sure the bar ended up parallel to the ground. Using this method, you also need to measure the weight of the bar by having the drive end turn freely and have the end of the bar on the scale. Can be fairly accurate if you set it up properly. These types of wheel bearings typically don't have much initial preload torque as they tighten somewhat as they heat up from running down the road.

When replacing the rear wheel bearings, it's recommended to replace the collapsible spacer (inside wheel hub). The spacers permanently collapse in length slightly when torqued up. After re-installing the rubber-filled axle coupling, torque the nut to 101.3 ft-lbs. You should also replace seals.

Having Fiat part numbers can sometimes really help when trying to locate an elusive part.

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To Karl: Thanks for the MWB tip and picture, I had forgotten about that section of their website, very helpful!

To Gil: I'm 99% sure it's wheel bearing, a rumbling noise that eases when I curve left (unloading the left wheel), varies linearly with car speed, unaffected by engine speed or transmission position (in gear or in neutral), and I can feel the vibration in the steering wheel. I've had noisy wheel bearings on other cars and am familiar with the symptoms. I've received the front wheel bearings and spindle nuts I ordered, will start the job today.

It may be germane that I've got 1/4" wheel spacers on the fronts and have been running Chromadora alloys ("Iron Cross" style, is that CD-16? - I don't recall) which may have the wrong offset and combined with the spacers could be putting too much load on the bearings - thoughts?

Roger what you said about trying to find an accurate low-range torque wrench, I'm struggling with that myself. I'm an aerospace engineer by trade and we had constant problems with torque wrench calibration and proper usage in the space business, where EVERYTHING gets torqued to a spec value. We sometimes used a spring scale ("fish scale") of known or tested accuracy, attached to a breaker bar at a carefully measured fixed distance from the working end, and pulled to whatever force gave us the needed torque. Basically the same process you used but with a spring scale instead of fixed weights.

I'm disappointed that my usual favorite Fiat vendors, or RockAuto, didn't have the bearings I need in stock, so I had to go to eVilBay and hope the vendors there had correct applications listed for their items. Guess I'll find out......
 
The front wheel bearings on an 850 are so understressed that I doubt that the offset of the rims would actually affect them. CD 16s have a offset of 25 or 27, many people run ‘Abarth’ rims which have a zero offset, you effectively are running them at the same offset as those rims, I have never heard of someone having an issue with wheel bearings and wheels in that offset range.

More likely old grease and sitting for extended periods or the incursion of moisture and time.
 
Replaced both front wheel bearing sets yesterday, though I cheated by re-using the existing outer raceways in both hubs (they seemed to be in perfect shape). Front end is totally quiet now and the vibration is gone from the steering wheel. Didn't look at the rears, probably nothing needed back there. Used Mobil-1 synthetic grease, yummy red color, looks like raspberry jam, it was a struggle not to taste it...... Thanks all for the help!
 
Replaced both front wheel bearing sets yesterday, though I cheated by re-using the existing outer raceways in both hubs (they seemed to be in perfect shape). Front end is totally quiet now and the vibration is gone from the steering wheel. Didn't look at the rears, probably nothing needed back there. Used Mobil-1 synthetic grease, yummy red color, looks like raspberry jam, it was a struggle not to taste it...... Thanks all for the help!


Dave,
Do you recall what socket size you used for the front spindle nuts when you replaced the bearings?
thanks
David
 
Oh, man - forgot already, but I looked in my toolbox and found a 30mm with what might be bearing grease on it, so that's my guess - wish I could be more helpful!
 
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