Technical Wheel bearings

[AndrewRL]

So I'm busy thinking through the tasks for 2017...so this is probably the first of many questions to come

Last year's MOT had the advisory "nearside Rear wheel bearing has slight play 2.6.2" so I probably need to do something about this before the next MOT.

Question is....is this best left to experts/those like most of you with lots of experience or is it something a relative beginner can tackle? I've looked through Haynes (mainly gobbledegook to me but may make more sense when following "live" although there seems to be a lot to remove before you get to the bearings); I've also studied the parts diagram/catalogue (but the bearings part seems to be floating above the rest of the diagram so I am not quite sure how it all fits together). I have looked through threads here and it sounds like it is quite complicated/full of potential issues and may require specialist tools (??)

Also...
(1) should both sides be replaced at the same time?
(2) if I order the parts for a local garage do I just need the replacement bearings (as per pic attached from FD Ricambio) or other parts as well?

Many thanks as always.

 

[gordinir8]

I am on this process right now and I think that if you are not confident go to a shop but be sure that they know how to do it.
You don't need any special tools except from a good strong vice since this is better to be done out of car as an assembly. On the other hand if you don't mess with it you will not learn and this is a very interesting and precise task.

You can do on side first but if your budget is ok better do both.
The bearing kit you have at the photo will do. You need two seals two bearings the spacer and a cotter pin.

 

[fiat500]

One advantage of doing this is that it will make your steering more precise as the rear wheels wander a little when the bearings are worn.

 

[timgarman]

Interesting Peter. I've noticed a wandering back end

Wheels have been aligned but not balanced yet.

Tim

 

[Luxe]

Has anyone had their flexible joint start to fail? On certain point when accelerating I will get a rubbing sound coming from the left rear wheel. When I let off the accelerator slightly the noise goes away. I took a look under the car and the flexible joint on the left rear wheel only looks shiny like it is rubbing.

 

[fiat500]

The flexible couplings are a weak point in the drivetrain. Although I was careful to avoid that failure by fiitting genuine Fiat couplings during my restoration, in days of yore I had recurring problems with couplings that disintegrated the way you describe.

 

[AndrewHarvey]

I have fitted an upgrade

 

[AndrewHarvey]

There is an upgrade for the coupling which is in essence a constant velocity joint (cv joint) they are well engineered if a little pricy at £140 for a set.
They were not difficult to fit and hopefully fit an forget for uprated engines....

 

[Luxe]

Did you just replace the flexible joint or did you order some other bit (washers/nuts)?

 

[AndrewHarvey]

I've replaced everything. .....quite literally.....

 

[fiat500]

Did you just replace the flexible joint or did you order some other bit (washers/nuts)?

When you replace the flexible joint, like for like, you could get away with changing that alone, depending on how precise you want to be.
The big nut can be re-used if it is the castellated one with a split-pin.
Technically, you are loosening the bearing pre-load so you should really replace the collapsible spacer and if doing so you may as well replace the seal and bearings. But I think many people would chance skipping that stage and leave it undisturbed.
I replaced the setscrews holding the driveshafts to the flexible couplings as these tend to get gnarled up.
If you can find genuine Fiat parts I would pay the bit extra for those.

 

[Luxe]

Did you install the flexible joint any specific way? I received them yesterday and where the shaft goes through on the inside of the rubber portion one side is flush with the rubner and the otherside has a slight lip. Also did you just hand snug up the castellated nut?

 

[gordinir8]

If you don't have the castle nut tight and the preload set correctly you will end up with damaged axles as in my case. Because of axle side play bearing seats became worn. Had to replace both axles

 

[The Whitakers]

Gents


So I am about to undertake the full replacement of bearings, drive couplings etc and need to get my head around something.....


The rear wheel bearings - So as they are taper bearings and one should 'never' over tighten a taper bearing am I correct in saying you 'pound' the castellated nut up to crush the central bush up until you have no play on the bearings?


I will hold my hand up and say that I haven't read up in detail as yet it is only what I have scan read on here but the cogs started grinding when I stripped the old ones out as to the parts build up of what I was looking at.


Regards


Rob

 

[the hobbler]

Middle barton garage have informed me that when replacing the flexible coupling you do NOT need to replace the collapsable spacer, but you DO need to tighten the nut back up to regain the correct rotational torque on the bearings. It is not an easy job, particularly on the O/S bearings. The rotational torque is 1 lb (one pound) at 4.3ins. I have made up a tool which enables me to hang a 1lb weight at 4.3ins from the centre of the hub and when the hub will move with just a VERY light touch to the weight, that is the correct torque.I have also found that there are 2 styles of collapsable spacer---1 which is practically identical to the original Fiat part and the other which is slightly thicker and a REAL bugger to collapse. They are of different colour--I will go into the workshop later and see which is which

 

[The Whitakers]

Middle barton garage have informed me that when replacing the flexible coupling you do NOT need to replace the collapsable spacer, but you DO need to tighten the nut back up to regain the correct rotational torque on the bearings. It is not an easy job, particularly on the O/S bearings. The rotational torque is 1 lb (one pound) at 4.3ins. I have made up a tool which enables me to hang a 1lb weight at 4.3ins from the centre of the hub and when the hub will move with just a VERY light touch to the weight, that is the correct torque.I have also found that there are 2 styles of collapsable spacer---1 which is practically identical to the original Fiat part and the other which is slightly thicker and a REAL bugger to collapse. They are of different colour--I will go into the workshop later and see which is which

Well I have come across some weird things in my life but that beats everything...…...well done the Italians...……..engineering precision is obtained by hanging weights of certain counter levers......I'll fab up a tool later then to 4.3 Inch's and get a pound weight...….( I mean inch's what even are they?)….


Thanks for the trouble of highlighting the different spacers, it is appreciated...…


Rob

 

[the hobbler]

The "1lb at 4.3ins" tool is a "bush-mechanics" method of ascertaining the correct rotational torque. The CORRECT method, is to use the original Fiat tool, part number:--A.95697, and to tighten the stub-axle nut until you get a rotational torque of "0.36 ft,lbs (50kgmm). Fiat also instruct (insist!) that if by chance the nut is over-tightened, you have to go through the whole proceedure again with A NEW SPACER! However, being that the chances of finding an original Fiat tool are, to put it mildly, remote, the "bush-mechanics" method has to be used. The 'brownie points' for coming up with the actual dimension/wieght of this method must be passed to Peter in Nairn---I cannot take the credit for them.
The tool that I came up with uses 2 bolts that will fit into the wheel-bolt threads and a bar with 2 grooves and a slot. The 2 grooves are on opposite side of the bar and locate OVER 1 bolt and UNDER the other bolt--the small slot is there to hang the weight from. One does have to measure carefully when making the bar as the slot for the weight has to be 4.3ins from where the bar passes the centre-line of the stub-axle.
With regard to the collapsable spacers---1 version is a 'plain' metal colour and the other version is 'goldy/bronze' colour--the version to get is the 'plain' version,it is noticeably lighter in size/construction

 

[Toshi 975]

Just in case anyone should be interested I have a new set of SKF made in Italy & top quality front wheel bearings going spare. Suit the 500 or 1st series 126. I have later 126 stub axles so cannot use them.

 

[The Whitakers]

So here's a bit of a strange one, So I drifted the bearing races in last night and rebuilt the hubs shafts back in and proceeded to tighten up the castellated nuts and all I can say is there was no crushing of the center bush witnessed before the bearing became tight? (pretty much tightened them up with the socket in my hand)


I did measure one of the new bushes alongside the old ones and they were pretty much identical.


I think I will strip them apart again and have a good inspection as I am not happy with them.


RW

 

[gordinir8]

I think replacement of my rear bearings and shafts eventually, was my biggest Odyssey in my 500 trip so far. You can reed it here if you have the time: https://www.fiatforum.com/500-classic/446102-problem-transmition-please-help.html

I just want to highlight this. Crushing the new spacers was impossible, probably new spacers are much stronger than they should, i almost damage a new shaft and nut so what i did was to reduce the length of the crusher in my lathe. (local 500 mechanic is doing the same by hand in his grinder disk!!) So be careful with that. And a pic of my 4.3in/lb special tool!!