Replacing front brake disc shields

[loki_the_glt]

I've got to replace the front shields on the Exxon Valdez (1997 940) as the old ones have more holes than metal.

Is the hub nut a 27mm or a 36mm one? I have seen both sizes quoted and want to make sure before starting the job that I have the correct socket.

The process itself looks straightforward:

jack up and support the front end;
remove the road wheel;
undo and secure the caliper;
remove the disc and hub nut;
apply heat/penetrating fluid/"industrial language"/cutting torch to the old backing plate;
clean up the mounting and apply sticking plaster/soothing balm to injuries;
fit new plate;
re-install disc, hub nut, caliper and road wheel, tightening as you go;
have another brew and biscuit/pastry of choice;
attend minor injuries clinic.

If anything is missing from the above please feel free to add it in.

[360beast]

I'm pretty sure it is a 36mm but it needs to be a thin walled socket as a normal thickness one doesn't fit inside the recess.

[Laird Scooby]

Originally Posted by loki_the_glt

I've got to replace the front shields on the Exxon Valdez (1997 940) as the old ones have more holes than metal.

Is the hub nut a 27mm or a 36mm one? I have seen both sizes quoted and want to make sure before starting the job that I have the correct socket.

The process itself looks straightforward:

jack up and support the front end;
remove the road wheel;
undo and secure the caliper;
remove the disc and hub nut;
apply heat/penetrating fluid/"industrial language"/cutting torch to the old backing plate;
clean up the mounting and apply sticking plaster/soothing balm to injuries;
fit new plate;
re-install disc, hub nut, caliper and road wheel, tightening as you go;
have another brew and biscuit/pastry of choice;
attend minor injuries clinic.

If anything is missing from the above please feel free to add it in.

I had to change the front wheel bearings on mine a few years back and i'm fairly sure it was a 32mm nut holding the hub on. Might be wrong and it was a 36mm with the replacement being 32mm though. Fairly sure the replacement that came with the new hubs/bearings was a different size.

I think it'll be a case of "Suck it and see", i know on my other beast the OE nut is 32mm but aftermarket suppliers send a 36mm nut (same thread size as OE though) mostly although i've heard of 30mm nuts as well. That is on the driveshaft that goes through the hub and is torqued to ~315lbft, much higher than the Volvo!

I therefore suspect there is one size on the Volvo that is the OE size but the nuts supplied with aftermarket bits may well be different.

As for your method statement, it sounds about right except for no mention of the pads - presumably dealt with alongside the caliper though.
That aside, a bit sparse on the application of Curses and Naughty Words and refreshments for my liking, i'd need much more of those in my method statement!

[Ian21401]

The front hub nuts on my 1992 940 are 36 mms. I had to buy a suitable socket. Not sure about the “thin wall” as mentioned by Luke.
They a VERY tight.
I managed to free the nearside one with a long breaker bar but could not move the offside one. Extending the breaker bar with a scaffolding pole threatened to snap the breaker bar or burst the socket. I took the car to my friendly local garage who loosened it with an impact wrench. Then I tightened it enough to drive the car home.
Take care when removing the hub as the bearings are a loose fit. Wrap your fingers around the back of the hub as you remove it to prevent the bearing dropping out.
The wire to the ABS sensor is located in a small bracket attached to the back plate. This will need to be removed and transferred to the new back plate. I think that it was originally secured with a very small nut and bolt which was so badly corroded it needed to be cut. I secured the bracket to the new back plate with a pop rivet.
I bought replacement hub nuts from my dealer ( VO 1387624 ) but refitted the old nuts with thread lock.
Haynes states torque is 100Nm plus 45 degrees.

[griston64]

99.9% certain its a 36mm socket as I bought one last year for my impact wrench. I also replaced the bolts holding the plate to the strut as they were completely knackered.

I can double check when I get home if you want ?

[griston64]

Originally Posted by griston64

99.9% certain its a 36mm socket as I bought one last year for my impact wrench. I also replaced the bolts holding the plate to the strut as they were completely knackered.

I can double check when I get home if you want ?

Just checked and it was 36mm. I just bought a standard 1/2 drive impact one and it fitted the recess fine

[TonyS9]

Just pop the cover off to check, you might even be able to do it without removing the wheel.

Make sure you have a good breaker bar, I just about managed with 0.6m, I struggled to get it fully tightened with the bar nearly breaking in the process. Probably 1m is needed and ideally 3/4" drive.

The bearing in later cars (ie yours) are integrated with hub, they won't fall out.

If you have high miles and are getting steering wobble under hard braking you might want to consider new hubs in the process. The bearings are not adjustable and when worn just become loose. Mine were gone at 170,000 miles but not detectable by the normal hand tests.

[griston64]

A breeze to get off with an impact wrench. Angle tightening not quite as easy

[Laird Scooby]

Originally Posted by TonyS9

Just pop the cover off to check, you might even be able to do it without removing the wheel.

Make sure you have a good breaker bar, I just about managed with 0.6m, I struggled to get it fully tightened with the bar nearly breaking in the process. Probably 1m is needed and ideally 3/4" drive.

The bearing in later cars (ie yours) are integrated with hub, they won't fall out. They can and they do!!!!!

If you have high miles and are getting steering wobble under hard braking you might want to consider new hubs in the process. The bearings are not adjustable and when worn just become loose. Mine were gone at 170,000 miles.

I used a 6ft scaffold pole on a 3/4 drive socket set to remove. Torque wrench and 1/2" drive to refit with 2' breaker bar to do the angle with a protractor although 45deg is fairly easy to guess.

New hubs including bearings can be scarily expensive, especially if they don't need doing yet.

[jpliddy]

Originally Posted by TonyS9

Just pop the cover off to check, you might even be able to do it without removing the wheel.

Make sure you have a good breaker bar, I just about managed with 0.6m, I struggled to get it fully tightened with the bar nearly breaking in the process. Probably 1m is needed and ideally 3/4" drive.

The bearing in later cars (ie yours) are integrated with hub, they won't fall out.

If you have high miles and are getting steering wobble under hard braking you might want to consider new hubs in the process. The bearings are not adjustable and when worn just become loose. Mine were gone at 170,000 miles but not detectable by the normal hand tests.

hi tony
i have just been experiencing some steering wobble when braking at higher speeds 60mph ,no other issues so possible hub is my problem ?