theALPINAregister.com Forum Index theALPINAregister.com
The Forum section of www.theALPINAregister.com
 
 FAQFAQ   SearchSearch   Site SearchSite Search   Forum SearchForum Search   MemberlistMemberlist   UsergroupsUsergroups  GalleryGallery   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Autumn Love

 
Post new topic   Reply to topic    theALPINAregister.com Forum Index -> Charles's Blog
View previous topic :: View next topic  
Author Message
Charles
Moderator
Moderator


Joined: 23 Jun 2003
Posts: 6884
Location: Oxford

PostPosted: Fri Oct 26, 2018 5:37 pm    Post subject: Autumn Love Reply with quote

Just picked up the car after an Inspection 1 plus a few extras - for the record, I managed to obtain 10 litres of Castrol Edge 5W-40 from Opie Oils for a meagre 70.

That was the easy bit ....

As regular readers will know, I have been struggling with uneven heat distribution in the cabin - passenger side lovely and warm but drivers side tepid at best. Now this has been fine in the summer months but after one and a half winters requiring extra layers of clothing for the driver whilst passengers are in t-shirts, I finally bit the bullet and agreed to have the dash out to investigate.

It transpires that the right hand third of the matrix was barely warm whilst the remainder was toastie. Given that there is a dividing wall the drops down from the heater box to separate left and right hand air flow/heat across the matrix, this would explain the symptoms. The cause was a partially clogged matrix that had refused to clear with back-flushing previously, so a new one has been fitted and I am delighted with the even warmth on both sides of the cabin Very Happy

At the same time, I needed to replace the rear diff carrier bush as it had started cracking and, once the diff was out, one of the forward diff carrier bushes was doing the same, so we changed all three.

With everything apart at the back end, we also decided to eliminate the annoying squeak that was still there despite recent attention. New ARB bushes were fitted - these aren't standard 330i items BTW and are actually those fitted on a 330d - as these were the suspected culprit. The old ones were looking very tired but the squeak was still present. Further investigation finally revealed that both lower ball joints were "excessively tired" and new ones have finally silenced the rear end Very Happy

And finally, we took the opportunity to investigate the relatively new front discs/pads as I had been suffering from serious steering wheel vibrations when braking firmly - something which had been happening from pretty much as soon as they were fitted. Good thing we looked at this as there was a nasty high spot (warp) in the o/s disc and a slight one on the n/s too. One good skim later and everything is now as it should be Very Happy

So I now have a hot cabin, a silent rear end, vibration-free steering under braking and, as an added bonus, the whole rear end feels remarkably tight yet supple and adds confidence when pushing on.

Happy days Very Happy
_________________
Charles
Teacher of Chemistry and driver of ALPINAs - not necessarily in that order Wink
B3S Touring (49/116) - been to the moon and now on the way back!
Renault Grand Espace - not mine but the wife's!
Back to top
View user's profile Send private message
ali
ALPINA
ALPINA


Joined: 10 Feb 2007
Posts: 1955
Location: Edinburgh

PostPosted: Sun Oct 28, 2018 1:39 pm    Post subject: Reply with quote

It's the little things that make all the difference and as usual you have managed to crack the nut on them all.
Great work by the mechanics to get to the bottom of it all.
I'm surprised that a warped disc can be skimmed flat again.
I was always under the impression that if they warped then they were bin fodder?
Glad you are happy she is back to full health again

Slightly off topic as I can't find your Dynavin thread but how is the sound quality out of your Dynavin unit?
I am still really struggling to get a decent sound especially at the bottom end of the spectrum and suspect my chinese Extrons headunit to be the culprit, not the speakers.
Are you running standard E46 speakers and is the sound quality any good?
I have noticed recently with driving both my B3 back to back that the E46 has the worst sound imaginable.
_________________
B3 3.3 Touring #108
B10 V8 #540
B3 3.0 Biturbo #107
E46 M3 Convertible
Back to top
View user's profile Send private message
Charles
Moderator
Moderator


Joined: 23 Jun 2003
Posts: 6884
Location: Oxford

PostPosted: Sun Oct 28, 2018 2:47 pm    Post subject: Reply with quote

ali wrote:
I'm surprised that a warped disc can be skimmed flat again.
I was always under the impression that if they warped then they were bin fodder?

I am careful to describe it as a warp but it is likely to have been caused by hot pads and sitting on the brake pedal, allowing a heat soak to distort the metal in the disc where the pads are in contact. If you can imagine just taking enough surface of both front and back faces to slice of the top of the high spot and there you go


Quote:
Slightly off topic as I can't find your Dynavin thread but how is the sound quality out of your Dynavin unit?
I am still really struggling to get a decent sound especially at the bottom end of the spectrum and suspect my chinese Extrons headunit to be the culprit, not the speakers.
Are you running standard E46 speakers and is the sound quality any good?
I have noticed recently with driving both my B3 back to back that the E46 has the worst sound imaginable.

I am using standard E46 speakers with the Dynavin, which comes with very accommodating equaliser software. It's taken me a while to get the sound the way I like it, but it is possible. The biggest problem with the Touring is that I always run with the boot cover closed and so the rear speakers become muffled.
_________________
Charles
Teacher of Chemistry and driver of ALPINAs - not necessarily in that order Wink
B3S Touring (49/116) - been to the moon and now on the way back!
Renault Grand Espace - not mine but the wife's!
Back to top
View user's profile Send private message
ade and liz flint
ALPINA
ALPINA


Joined: 02 Jul 2010
Posts: 7092

PostPosted: Sun Oct 28, 2018 3:54 pm    Post subject: Reply with quote

Charles wrote:
ali wrote:
I'm surprised that a warped disc can be skimmed flat again.
I was always under the impression that if they warped then they were bin fodder?

I am careful to describe it as a warp but it is likely to have been caused by hot pads and sitting on the brake pedal, allowing a heat soak to distort the metal in the disc where the pads are in contact. If you can imagine just taking enough surface of both front and back faces to slice of the top of the high spot and there you go


This is a complex subject and often 'warping' as described is not permanent. Much of my dynamics career was spent dealing with 'bent' or 'warped' steel shafts, the causes of and rectification of. Heat and its effects is very interesting, as is material deposition from outside sources: in this case, brake friction material, or rust in the case of a car that has stood awhile. A simple, permanent(!) brake disc distortion caused by external heating source leading to localised material changes can be machined out with a 'skim' as long as the discs stay within accepted thickness rules and the hubs (datum faces) are themselves flat. However, the removal of the 'high spots' leads to weight changes and imbalance and may lead to vibration from the spinning disc if too much mass change results. Note the high spot and the heavy spot are rarely in the same position, and it is impossible to balance for a warped disc. Ditto a warped or buckled wheel: this cannot be cured by balancing (although some tyre fitters will try valiantly, but fail), only straightening.

The usual causes of disc 'warping' are as said rusted discs where pads stick to them leading to friction material deposition on the disc face and a high friction 'spot' on the disc, or a sticking caliper which leads to the pads rubbing on the high spot of the disc (they all have one!) as the disc rotates in usual service and causing localised thermal changes to the disc material and hence vibration when the pedal is pressed. This should be addressed before changing any disc parameters. Temporary 'warping' Can occur upon heavy braking if the pedal is not released on completion of the braking as again heat is locked into one angular position on the discs and causes localised material changes, which usually then dissipate when the car is moving again.

Note: worn front wishbone mounts or ball joints amplify any 'high spot' or 'warping' of a brake disc. It can be that perfectly normal brake disc characteristics are worsened by poor control from the front suspension arms: effectively the only lateral damping the brake system has.

Personally, I'd investigate why my discs have 'changed shape' and bin them, then fit new discs and pads having identified and rectified the cause of issue.
_________________
Current:
E91 B3SBiturbo #127
981 Porsche Cayman GTS
Focus STline dog wagon

Previously loved:
ALPINA: E92 B3SBiturbo #285, E90 D3Biturbo #097, E85 Roadster S #168 & variety of 'grey' 4 and 6-cyl BMW lumps.
PORSCHE: Macan S, Cayman 981 S
Back to top
View user's profile Send private message
rc944
ALPINA
ALPINA


Joined: 01 Sep 2013
Posts: 780
Location: London / Bucks

PostPosted: Sun Oct 28, 2018 9:00 pm    Post subject: Reply with quote

Charles wrote:

I am careful to describe it as a warp but it is likely to have been caused by hot pads and sitting on the brake pedal, allowing a heat soak to distort the metal in the disc where the pads are in contact.


never would have thought that. how long would you need to keep the brake pedal depressed for that to happen and wouldn't the heat just dissipate anyway before it could have that affect?

what brand were the new pads/discs?

learn something new everyday!
_________________
Alpina E46 B3s Coupe
E39 525i Sport Touring (again)
Ducati 748R
E39 525i Sport Touring (sold)
E46 330i Sport Touring (sold)
Porsche 964, 968 CS, 944 S2 (sold)
VW Mk4 R32 (sold)
Back to top
View user's profile Send private message
Charles
Moderator
Moderator


Joined: 23 Jun 2003
Posts: 6884
Location: Oxford

PostPosted: Mon Oct 29, 2018 1:17 pm    Post subject: Reply with quote

ade and liz flint wrote:
Personally, I'd investigate why my discs have 'changed shape' and bin them, then fit new discs and pads having identified and rectified the cause of issue.

This started virtually straight away after a new set of discs and pads were fitted caused by this muppet not bedding in the brakes properly and sitting on them after a number of heavy braking events shortly after fitting. All the front joints/bushes/etc have been checked and are absolutely fine and so I am satisfied with the reason for the "warp". The amount of material removed was not only minimal but also the same on both faces and across the whole disc width and I have not experienced any vibration since, so it looks like this has resolved the issue. BTW, this has happened before and been resolved in a similar fashion, so I am happy that I am not masking a deeper problem.

rc944 wrote:
how long would you need to keep the brake pedal depressed for that to happen and wouldn't the heat just dissipate anyway before it could have that affect?

Difficult to answer accurately as it depends on how much heat has built up and how thick the disc is - but heavy braking from 70 to standstill and then sitting on the brakes at the traffic lights/obstruction is not the best plan

Quote:
what brand were the new pads/discs?

Standard BMW OEM discs and pads
_________________
Charles
Teacher of Chemistry and driver of ALPINAs - not necessarily in that order Wink
B3S Touring (49/116) - been to the moon and now on the way back!
Renault Grand Espace - not mine but the wife's!
Back to top
View user's profile Send private message
ade and liz flint
ALPINA
ALPINA


Joined: 02 Jul 2010
Posts: 7092

PostPosted: Mon Oct 29, 2018 1:23 pm    Post subject: Reply with quote

rc944 wrote:
Charles wrote:

I am careful to describe it as a warp but it is likely to have been caused by hot pads and sitting on the brake pedal, allowing a heat soak to distort the metal in the disc where the pads are in contact.


never would have thought that. how long would you need to keep the brake pedal depressed for that to happen and wouldn't the heat just dissipate anyway before it could have that affect?


I described how this occurs in my post. Effectively you heat up the high spot on the discs more than the rest of the surface, and that creates a vibration as the disc passes the pad when the pedal is depressed. Usually the amount of pedal pressure used will create different vibration responses as the suspension takes higher or lesser loads and applies damping. The amount of vibration depends on the 'size' of the high spot, the amount of heat entering the material, and the control given by the front wishbone assemblies to damp the lateral motion of the brake assembly on the suspension strut as a result of the heating effect. Holding the brakes on once stopped can further affect things as it can create a temporarily 'locked in' hot spot creating further vibration once the car is again in motion and the brakes used. Note, these thermal changes are usually temporary unless a permanent material change has occurred: if this is so, the discs should be replaced as they may have yielded and may now be likely to fail under braking in future.

Ironically, I collected my sons F21 from Cardiff yesterday as some utter oik has kicked off his door mirror whilst parked up (mirror was in the 'up' position for safety and still they do it Evil or Very Mad). After taping the assembly together to make it road legal I drove it back and discovered the brakes are vibrating horribly. I asked him later if he'd had this issue long, to be told 'no, never had it'. So, I have an investigation to do as well as stripping out his door and obtaining a new (very expensive) mirror housing. It passed it's mot with no advisories 2 days before I drove it, so no suspension issues are expected. Seems it may be a corrosion issue following rain on Saturday....but odd it hasn't eased after 30miles driving in heavy stop start M4 traffic!

Edited after front brake overhaul: I fitted these discs and pads when he bought the car, and they are barely worn in the 2 years he's had the car (he's light on brakes: just like me!), but they were very gummed up with road grime. Spinning the discs, it was clear the significant high spot of each disc was not being cleared by the pads due to a limited floating effect of the calipers: BMW calipers are prone to this. N/S stripdown, cleaned and pins polished before reassembly with minimal copper grease. O/S lower pin was binding somewhat on removal, and a burr had worn into the pin. All cleaned and polished out and reassembled. Both caliper and pad assemblies now float over the discs as they are intended to: road test to follow once drivers' door rebuilt.
_________________
Current:
E91 B3SBiturbo #127
981 Porsche Cayman GTS
Focus STline dog wagon

Previously loved:
ALPINA: E92 B3SBiturbo #285, E90 D3Biturbo #097, E85 Roadster S #168 & variety of 'grey' 4 and 6-cyl BMW lumps.
PORSCHE: Macan S, Cayman 981 S
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    theALPINAregister.com Forum Index -> Charles's Blog All times are GMT + 2 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group