Torsen diff and brake rollers at MOT centre

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motco
Joined: Tue 18 Aug, 2009 19:12
Posts: 634

  Z3 roadster 2.2i

Torsen diff and brake rollers at MOT centre

Post by motco » Tue 13 Sep, 2016 18:02

Does anyone know whether a car with a Torsen differential should be brake tested on rollers or not please? Mine just scraped the handbrake efficiency today at MOT - the tester used the Tapley in-car tester instead of rollers because he didn't know for sure.

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Southernboy
Joined: Thu 07 Oct, 2010 13:39
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  Z3 roadster 3.0i
Location: Johannesburg

Re: Torsen diff and brake rollers at MOT centre

Post by Southernboy » Tue 13 Sep, 2016 20:16

Brakes operate on both rear wheels equally - or as near as dammit to equally - so the diff has no bearing on the braking - just like it has no bearing on being used whilst the car is being driven on a road. The same applies to the handbrake... :wink:
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siwilson
Joined: Fri 19 Jun, 2009 10:54
Posts: 782

  M roadster S54
Location: Horley

Re: Torsen diff and brake rollers at MOT centre

Post by siwilson » Tue 13 Sep, 2016 20:39

What he is asking is if its OK for one wheel to be spun by the rollers while the other is held still. I know its NOT OK on a clutch pack diff, but not sure on TorSen. I think your tester did the smart thing. I wish more were like him.
2001 M roadster S54 Laguna Seca Blue

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motco
Joined: Tue 18 Aug, 2009 19:12
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  Z3 roadster 2.2i

Re: Torsen diff and brake rollers at MOT centre

Post by motco » Wed 14 Sep, 2016 07:40

siwilson wrote:What he is asking is if its OK for one wheel to be spun by the rollers while the other is held still. I know its NOT OK on a clutch pack diff, but not sure on TorSen. I think your tester did the smart thing. I wish more were like him.
It's a good test centre - I have used it for more than fifteen years and they are sympathetic to my Westfield's quirks (low slung chassis with odd bits that bottom on the ramp) too. They have always used the Tapley device on my Z but yesterday the handbrake performance was marginal (rubbish BMW drum system) and he was asking if I knew for sure that Torsen was unsuited to the roller test because it might give better figures. After a few goes with the Tapley he got a 'pass' figure so it became irrelevant - for this year...

Thanks for the replies chaps. :)

siwilson
Joined: Fri 19 Jun, 2009 10:54
Posts: 782

  M roadster S54
Location: Horley

Re: Torsen diff and brake rollers at MOT centre

Post by siwilson » Wed 14 Sep, 2016 08:06

Have you had the discs off to take a look at the handbrake shoes?

Since the handbrake doesn't do any real braking (just a lock when already you are already stationary), the shoes don't wear and have probably been in there since new. They do degrade though and can fall apart. I recently noticed my right wheel handbrake was not catching as much and when I looked at the shoes they were in in a shocking state, rusty and with missing pad material.

Worth a look!
2001 M roadster S54 Laguna Seca Blue

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motco
Joined: Tue 18 Aug, 2009 19:12
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  Z3 roadster 2.2i

Re: Torsen diff and brake rollers at MOT centre

Post by motco » Wed 14 Sep, 2016 12:23

siwilson wrote:Have you had the discs off to take a look at the handbrake shoes?

Since the handbrake doesn't do any real braking (just a lock when already you are already stationary), the shoes don't wear and have probably been in there since new. They do degrade though and can fall apart. I recently noticed my right wheel handbrake was not catching as much and when I looked at the shoes they were in in a shocking state, rusty and with missing pad material.

Worth a look!
No, I haven't had them off yet. It's a job in the pipeline. Reading how difficult it can be if corrosion has seized the disc retainer screw and/or the caliper carrier bolts, I shall set aside a half-day to do a bit of investigation before ordering parts. I also need to replace the lower front ball joints and I read that they can be difficult to remove too. There's no need to replace the lower arms if the joints can be replaced. The joints didn't even merit an advisory but I was verbally advised anyway.

Boosh
Joined: Sun 30 Nov, 2014 22:40
Posts: 304

  Z3 roadster 1.9i

Re: Torsen diff and brake rollers at MOT centre

Post by Boosh » Wed 14 Sep, 2016 12:40

When I had the ball joints done, it was just as cheap to buy new arms with ball joints and bushes mounted on.

Boosh.

Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2115

  Z3 roadster 1.9

Re: Torsen diff and brake rollers at MOT centre

Post by Del » Wed 14 Sep, 2016 18:29

Removing the rear disc can be OK if you squirt a small amount of your favourite penetrating fluid around the disc retaining screw and in the gap between the disc and the hub (where the wheel bolts go in) followed by a few sharp taps around the face of the disc/hub to send a “freeing-up shock” into the unit. My Haynes manual states the rear caliper hanger bolts are only set at 66nm at the factory on the Z3 which shouldn’t be too much of a problem – particularly if you let a bit of penetrating fluid soak in for a few minutes whilst you make a cup of tea.

You will just need to make your own assessment of the handbrake drum shoes when you remove the disc. As said already the age-related faults can include the friction material delaminating from the shoe backing plate, the spring kit being rusty/broken/weakened or the little “arrow pin” holding the shoe to the wheel backing plate can come loose caused by the hole in the backing plate rusting and no longer allowing the “arrow pin” to grip when twisted 90 degrees.

As said above already, if you are going down the DIY route it is much easier (and probably cheaper) to replace a complete front lower control arm rather than individual ball joints which still requires the removal of the old control arm and a garage/workshop press. If one ball joint has gone, the others won’t be far behind and the round bush is probably also worn.

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motco
Joined: Tue 18 Aug, 2009 19:12
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  Z3 roadster 2.2i

Re: Torsen diff and brake rollers at MOT centre

Post by motco » Wed 14 Sep, 2016 20:31

Dell, Boosh, many thanks for the tips. I shall try the Plus Gas route for the drums, and look at the price or new control arms if they have to come off anyway. I don't intend to stint the cost of looking after the car, after all it's a mere 45,000 miles and in pretty good condition. Hoping in the medium term that it will appreciate in value as older ones decay.

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motco
Joined: Tue 18 Aug, 2009 19:12
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  Z3 roadster 2.2i

Re: Torsen diff and brake rollers at MOT centre

Post by motco » Thu 15 Sep, 2016 15:35

Boosh wrote:When I had the ball joints done, it was just as cheap to buy new arms with ball joints and bushes mounted on.

Boosh.
The part is discontinued according to RealOEM, where did you get yours Boosh? Was it a repair kit, these seem available but we're back to the pressing out problem.

Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2115

  Z3 roadster 1.9

Re: Torsen diff and brake rollers at MOT centre

Post by Del » Thu 15 Sep, 2016 17:00

Had these on my car (from this BMW specialist firm) for the past 4-years.
http://www.ebay.co.uk/itm/BMW-E36-Z3-FR ... eKilV4bE_w

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motco
Joined: Tue 18 Aug, 2009 19:12
Posts: 634

  Z3 roadster 2.2i

Re: Torsen diff and brake rollers at MOT centre

Post by motco » Thu 15 Sep, 2016 17:14

Thanks Del, that's a lot of money when all I need really is a pair of these: http://www.ebay.co.uk/itm/331914632435? ... EBIDX%3AIT Maybe I should drop the arms off and try to remove the ball joints. This was all the MoT chap said were moving a bit.

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