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Brake Disc Problem


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Hello.

I have just recently finished a complete restoration of my 1973 TR6 where pretty much everything has been refurbished or renewed. The problem I have is that the pads only seem to be acting on the outside edge of the disc. They are new pads operated by new callipers on new discs. I know from the manuals that the callipers should have shims fitted on an "as required" basis to centralise the calliper about  the disc but since it seems central anyway there are no shims fitted. I'm wondering if this is the problem. This is occurring on both sides. Hopefully the photos show what is happening.

Has anyone had this problem or can anyone suggest how to remedy it. As always any help or advice is much appreciated.

Regards Dex

WIN_20190528_12_53_52_Pro.jpg

WIN_20190528_12_54_14_Pro (2).jpg

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Hi Dex

I can't really say that I have noticed. Did you clean the disc after installing to make sure there was no grease or dirt on them. If yes I would run a metal ruler over both discs and pads to check they are flat if your worried.

I do remember a few years back when installing new pads on a Audi that the they were slightly concaved. It puzzled me at the time, but thought maybe they were designed that way to help bed them in.

Roger

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Have you driven the car yet and given the new brakes a chance to bed in? And are the hub bearings properly adjusted for end float?

Looks to me that the pads will be fine after a few miles.

Nigel

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Never seen one do that before!

Assuming your wheel bearings are ok, I would wonder if there is a problem with the new calipers? 

Are the pistons actually at 90 degrees to the disc?

You could remove the calipers and pump the pads together and see if they touch outer edge first. Also make sure the pad material is parallel to the backing plate in case there is a fault with the pad manufacture.

The pads may bed themselves in eventually but your brakes could be **** for miles before they do, and something requiring an emergency stop could prove embarrassing!

Neil

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14 hours ago, Nigel Triumph said:

Have you driven the car yet and given the new brakes a chance to bed in? And are the hub bearings properly adjusted for end float?

Looks to me that the pads will be fine after a few miles.

Nigel

Hi Nigel

Yes I've driven 30miles so far and also checked the hub bearings so will probably give them a few more miles of careful stopping so as not to have any embarrassing moments as Neil suggested.

Dex

 

 

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My suggestion:

take out the pads. The pads should show the wear on the outside edge. Mark them or try to measure the wear. Install und drive. Look after few miles if the wear starts to increase. If so, you are good to go. If not, your calipers/discs may require some attention. 

Jochem

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Hi Jochem

The pads are standard pads from Moss they were in a box marked Classic Gold and I bought the discs some time ago at one of the internationals but I can't remember the make although they were from a reputable supplier. I took the pads out but it was very difficult to detect any wear at this stage so I think I'll do a few more miles and as suggested by Mike C try some heavier braking.

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Hi Dex

classic gold are not particularly highly regarded, and i would not use them for brake pads.

try swapping to something more brake specific, eg mintex or ferodo or ebc

also i have found that ‘basic’ brake disks can be uneven and prefer to invest a little more in a reputable brand here too.

try a better quality pad first is my recommendation

steve

Ps, do also follow the pad manufacturers bedding in recommendations, makes a big difference

Edited by Steves_TR6
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21 minutes ago, Steves_TR6 said:

Hi Dex

classic gold are not particularly highly regarded, and i would not use them for brake pads.

try swapping to something more brake specific, eg mintex or ferodo or ebc

also i have found that ‘basic’ brake disks can be uneven and prefer to invest a little more in a reputable brand here too.

try a better quality pad first is my recommendation

steve

Ps, do also follow the pad manufacturers bedding in recommendations, makes a big difference

Hi Steve

I did have EBC Green Stuff in initially but I've heard they need to get warm before giving maximum braking and with the braking only being on the outside edge I didn't want to drive in such a manner to get them heated up

Dex

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Dex,

have you bedded the pads in as per the manufacturers instructions?

This a specific procedure, and definately not just driving gently.

Looks to me like you have some material transfer, probobly exaserpated by the protective residue

used by the disc manufacturer.

Nothing wrong with the standard Moss pads, but you need to bed them in.

What I would do is strip the pads out, carefully clean both sides of the discs with brake cleaner, and perhaps fine emery

until shiny, scuff the pads with fine wet and dry or sandpaper, and then rebuild and bed the pads as per the manufacturers insructions,

they will be something like, brake steadily from 50mph to 20 mph, without locking the wheels, and repeat 6 - 10 times.

 

Can't see much of an issue the above won't cure, let us all know.

John.

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30 miles isn't very far to bed them in, particuarly since it sounds like you've been extremely gentle. An overly gentle approach to bedding in equals no bedding in.  Agree fully with JM's advice, and only if the discs look like that after a few 100 miles of fairly normal driving with a fair amount of braking will I believe you have a problem worth worrying about.

 

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Hi Dex,

while you have the pads out, measure the disc thickness, to verify if they are machined /produced parallel, so they are equally thick everywhere. Same for the pads.

Regards,

Waldi

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15 hours ago, Dex said:

Hi Steve

I did have EBC Green Stuff in initially but I've heard they need to get warm before giving maximum braking and with the braking only being on the outside edge I didn't want to drive in such a manner to get them heated up

Dex

My experience with them was they were no better when warmed up.

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18 hours ago, John L said:

In your second photo, could the inner part of the pads be touching on the shoulder at the inner part of the disc?

tr6 brake disc_LI.jpg

Good Spot John I'll check that out

Dex

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18 hours ago, John Morrison said:

Dex,

have you bedded the pads in as per the manufacturers instructions?

This a specific procedure, and definately not just driving gently.

Looks to me like you have some material transfer, probobly exaserpated by the protective residue

used by the disc manufacturer.

Nothing wrong with the standard Moss pads, but you need to bed them in.

What I would do is strip the pads out, carefully clean both sides of the discs with brake cleaner, and perhaps fine emery

until shiny, scuff the pads with fine wet and dry or sandpaper, and then rebuild and bed the pads as per the manufacturers insructions,

they will be something like, brake steadily from 50mph to 20 mph, without locking the wheels, and repeat 6 - 10 times.

 

Can't see much of an issue the above won't cure, let us all know.

John.

Hi John.

To be honest I haven't bedded the pads in as per manufacturers instructions but it seems as if this is something I must try, so as soon as the weather improves (not enough room in garage) I try everything you suggest ..Thanks

Dex

 

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17 hours ago, Waldi said:

Hi Dex,

while you have the pads out, measure the disc thickness, to verify if they are machined /produced parallel, so they are equally thick everywhere. Same for the pads.

Regards,

Waldi

Thanks Waldi I'll do this when I'm following John M's instructions

Dex

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  • 3 years later...

Hi, Regarding bedding brakes in its important to remember that you are trying to slow down a lot of weight with very little contact area. This results in very high temperatures being created quickly, as is highlighted by the usual smell! Overheating often leads to hardening of the lining, as in baking. It’s easy to end up with brakes that don’t work correctly until hot. Not ideal!

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