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-   -   Replacing front brake disc shields (https://www.volvoforums.org.uk/showthread.php?t=319291)

loki_the_glt Aug 18th, 2021 09:52

Replacing front brake disc shields
 
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 Aug 18th, 2021 10:26

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 Aug 18th, 2021 10:31

Quote:

Originally Posted by loki_the_glt (Post 2763178)
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! :err:

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! :thumbs_up:

Ian21401 Aug 18th, 2021 10:39

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 Aug 18th, 2021 10:59

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 Aug 18th, 2021 11:12

Quote:

Originally Posted by griston64 (Post 2763203)
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 Aug 18th, 2021 11:32

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 Aug 18th, 2021 11:38

https://i.postimg.cc/CnhG5J21/strut.jpg

https://i.postimg.cc/D8YrfrPv/shield_2.jpg

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

Laird Scooby Aug 18th, 2021 11:48

Quote:

Originally Posted by TonyS9 (Post 2763212)
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.

griston64 Aug 18th, 2021 11:58

Quote:

Originally Posted by Laird Scooby (Post 2763221)
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.

Cost from Volvo for front hubs is 2x271644- £281.60. Wheel hubs a pair
2x6819759- £109.80. ABS RING TO PRESS ON HUBS. a pair

I replaced mine with SKF which were still £100.00 each


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