➜ advanced search
Add a more detailed reply Start a new thread in the Brakes forum
Home -> Forums -> Brakes -> big rear discs

displaying posts 1 to 24 of 24

Author Subject: big rear discs
mxcrazy

Regular

Location: hastings

Registered: 22 Jun 2009

Posts: 456

Status: Offline
Post #1
With people upgrading discs, calipers, pads etc on the front of their cars, what are you doing about the rear?

Using bias valves, or leaving them as they are? With a bigger discs, or better calipers, less pedal effort is needed to lock the front wheels, thus, less pressure goes to the rear calipers as i understand.

I was looking for bigger discs but non vented, so they are not too heavy, and low and behold, 406 rear discs, 290mm diameter, 10mm wide.

Im sure some brackets can be made to relocate the stock rear calipers even.

Thoughts?
Posted 14th Apr 2010 at 02:38
Profile
oldbrownshoe

Seasoned Pro

Location: Holon Israel

Registered: 08 Aug 2008

Posts: 1,795

Status: Offline
Post #2
Bigger (substantially) front disks = longer stopping distance.

it's just so common mistake to only upgrade the front that it became a norm.

________________________________________

French military victories?
Did you mean French military defeats?
Posted 14th Apr 2010 at 02:59
Profile
mxcrazy

Regular

Location: hastings

Registered: 22 Jun 2009

Posts: 456

Status: Offline
Post #3
oldbrownshoe wrote:
bigger (substantially)front disks = longer stopping distance.


Why is that you think?

If they are really heavy then i can understand.
Posted 14th Apr 2010 at 02:57
Profile
phillipm

Seasoned Pro

Location: Rotherham

Registered: 15 Oct 2006

Posts: 20,607

Status: Offline
Post #4
I'd just uprate the rear pads if you need to get the balance back to the rear, do you really need the extra heat capacity of 290mm rear discs, or just the extra rear bias?

________________________________________

- Bespoke rollcages/additions/adjustments. Half cages right up to complete custom spaceframes - MSA/FIA spec, CDS, ROPT, T45, etc - PM me
Email me!
Custom-made polybushes available - need an odd size or fitment? - anything from batch work to one-off pieces.
Posted 14th Apr 2010 at 03:05
Profile
mxcrazy

Regular

Location: hastings

Registered: 22 Jun 2009

Posts: 456

Status: Offline
Post #5
Just thinking really phillipm, out load (quietly) so to speak (type).

Was thinking bore bias than anything, i know the weight is an issue but i would help surely, leverage effect.
Posted 14th Apr 2010 at 03:17
Profile
cress87

Seasoned Pro

Location: Norwich

Registered: 30 Mar 2007

Posts: 11,360

Status: Offline
Post #6
On my dad's 406, and presumably all the others, the rear discs incorporate a central drum which is utilised by the handbrake. I doubt they'd even fit onto a 306 hub.

________________________________________

Ph3 China blue GTi-6 330Ci///M Sport & NC23 CBR400RR Cool

You feed beefburgers to swans. Yes

I may have been speeding Mr Policeman but [a] I live for the 306 and [b] did you see that dog? omfg
Posted 14th Apr 2010 at 03:21
Profile
oldbrownshoe

Seasoned Pro

Location: Holon Israel

Registered: 08 Aug 2008

Posts: 1,795

Status: Offline
Post #7
Read this
http://www.stoptech.com/Products/BBK/balance.shtml
in a nutshell :
the optimal breaking occurs when all the tires are on the verge of it's grip just before sliding ,
violating the front/rear balance by applying more power to the front ,leads to locking the front tires before the rear ones exploit there full grip potential and since 4 tires participate in the breaking you loose in the total sum when the rear contribute less.


________________________________________

French military victories?
Did you mean French military defeats?
Posted 14th Apr 2010 at 03:24
Profile
t0mt0m

Regular

Location: Truro

Registered: 18 Jan 2010

Posts: 495

Status: Offline
Post #8
cress87 wrote:
On my dad's 406, and presumably all the others, the rear discs incorporate a central drum which is utilised by the handbrake. I doubt they'd even fit onto a 306 hub.


and even if they did why would you want to fit them??

________________________________________

1997 Diablo Red 1.6 xs! crashed and scrapped!
1998 Nile blue Gti 6
1999 Yamaha R6! maybe for sale soonish still in two minds!
Posted 14th Apr 2010 at 03:24
Profile
mxcrazy

Regular

Location: hastings

Registered: 22 Jun 2009

Posts: 456

Status: Offline
Post #9
cress87 wrote:
On my dad's 406, and presumably all the others, the rear discs incorporate a central drum which is utilised by the handbrake. I doubt they'd even fit onto a 306 hub.


Ahh, thats buggers that thought then.LOL i just ebay search for the discs and the pics came up with normal looking discs.
Posted 14th Apr 2010 at 03:25
Profile
mxcrazy

Regular

Location: hastings

Registered: 22 Jun 2009

Posts: 456

Status: Offline
Post #10
oldbrownshoe wrote:
Read this
http://www.stoptech.com/Products/BBK/balance.shtml
in a nutshell :
the optimal breaking occurs when all the tires are on the verge of it's grip just before sliding ,
violating the front/rear balance by applying more power to the front ,leads to locking the front tires before the rear ones exploit there full grip potential and since 4 tires participate in the breaking you loose in the total sum when the rear contribute less.




Yep, thats what i though, hence the reason to try and even the bias up between front and rear.
Posted 14th Apr 2010 at 03:26
Profile
simonjames

Seasoned Pro

Location: Whitland S.Wales

Registered: 23 Nov 2004

Posts: 6,219

Status: Offline
Post #11
i have the 290mm 406 v6 coupe rear disc, calipers i just need to trial fit then decide if i put the 406 drum for handbrake or alter the caliper somehow

________________________________________

All South Wales Members Click Here
Team Supercharged Black RALLYE ™ (Click Here for Build Project)
MY EBAY ITEMS

07943066306
Posted 14th Apr 2010 at 03:27
Profile
mxcrazy

Regular

Location: hastings

Registered: 22 Jun 2009

Posts: 456

Status: Offline
Post #12
t0mt0m wrote:
cress87 wrote:
On my dad's 406, and presumably all the others, the rear discs incorporate a central drum which is utilised by the handbrake. I doubt they'd even fit onto a 306 hub.


and even if they did why would you want to fit them??


Because they are bigger diameter, 290 as opposed to 247, more 'leverage' action hence less effort required to slow/lock the wheel.
Posted 14th Apr 2010 at 03:27
Profile
mxcrazy

Regular

Location: hastings

Registered: 22 Jun 2009

Posts: 456

Status: Offline
Post #13
simonjames wrote:
i have the 290mm 406 v6 coupe rear disc, calipers i just need to trial fit then decide if i put the 406 drum for handbrake or alter the caliper somehow


Is it a single disc then and separate drum?
Posted 14th Apr 2010 at 03:29
Profile
oldbrownshoe

Seasoned Pro

Location: Holon Israel

Registered: 08 Aug 2008

Posts: 1,795

Status: Offline
Post #14
mxcrazy wrote:
oldbrownshoe wrote:
Read this
http://www.stoptech.com/Products/BBK/balance.shtml
in a nutshell :
the optimal breaking occurs when all the tires are on the verge of it's grip just before sliding ,
violating the front/rear balance by applying more power to the front ,leads to locking the front tires before the rear ones exploit there full grip potential and since 4 tires participate in the breaking you loose in the total sum when the rear contribute less.




Yep, thats what i though, hence the reason to try and even the bias up between front and rear.


if you upgrade to more powerful front brakes and
then weakens it to balance front/rear ,you'v just wasted a loads of money and added weight.

________________________________________

French military victories?
Did you mean French military defeats?
Posted 14th Apr 2010 at 03:32
Profile
cress87

Seasoned Pro

Location: Norwich

Registered: 30 Mar 2007

Posts: 11,360

Status: Offline
Post #15
mxcrazy wrote:
simonjames wrote:
i have the 290mm 406 v6 coupe rear disc, calipers i just need to trial fit then decide if i put the 406 drum for handbrake or alter the caliper somehow


Is it a single disc then and separate drum?


They might be but I seem to remember the disc being offset inboard and the drum effectively being the 'inside' of the disc, if you see what I mean.

________________________________________

Ph3 China blue GTi-6 330Ci///M Sport & NC23 CBR400RR Cool

You feed beefburgers to swans. Yes

I may have been speeding Mr Policeman but [a] I live for the 306 and [b] did you see that dog? omfg
Posted 14th Apr 2010 at 03:36
Profile
phillipm

Seasoned Pro

Location: Rotherham

Registered: 15 Oct 2006

Posts: 20,607

Status: Offline
Post #16
oldbrownshoe wrote:
Read this
http://www.stoptech.com/Products/BBK/balance.shtml
in a nutshell :
the optimal breaking occurs when all the tires are on the verge of it's grip just before sliding ,
violating the front/rear balance by applying more power to the front ,leads to locking the front tires before the rear ones exploit there full grip potential and since 4 tires participate in the breaking you loose in the total sum when the rear contribute less.


Unfortunately, tyres have progressed a long way since the 306 was designed, and anyone running uprated brakes is also liable to be running on track on a grippy surface - where they have a lot more weight transfer to the front - so uprating the rear isn't always needed.

________________________________________

- Bespoke rollcages/additions/adjustments. Half cages right up to complete custom spaceframes - MSA/FIA spec, CDS, ROPT, T45, etc - PM me
Email me!
Custom-made polybushes available - need an odd size or fitment? - anything from batch work to one-off pieces.
Posted 14th Apr 2010 at 03:37
Profile
mxcrazy

Regular

Location: hastings

Registered: 22 Jun 2009

Posts: 456

Status: Offline
Post #17
It is a mis-conception that bigger discs are better for braking, if you can lock the brakes with stock brakes then you are getting more than maximum stopping power, however by using larger discs, multi piston calipers, better pads, you are reducing the effort needed to get maximum braking effect, and reducing fade from heat, if the brakes dont have to work as hard to get maximum braking effect it is easier on you and the brake components.

Agree?
Posted 14th Apr 2010 at 03:37
Profile
phillipm

Seasoned Pro

Location: Rotherham

Registered: 15 Oct 2006

Posts: 20,607

Status: Offline
Post #18
Bigger discs are only needed if:

a) You don't have enough thermal capacity with the stock discs - they're running too hot to be safe any more

b: You can't get more leverage by any other method.

c) Your wear rates are far too high on smaller discs.

________________________________________

- Bespoke rollcages/additions/adjustments. Half cages right up to complete custom spaceframes - MSA/FIA spec, CDS, ROPT, T45, etc - PM me
Email me!
Custom-made polybushes available - need an odd size or fitment? - anything from batch work to one-off pieces.
Posted 14th Apr 2010 at 03:40
Profile
simonjames

Seasoned Pro

Location: Whitland S.Wales

Registered: 23 Nov 2004

Posts: 6,219

Status: Offline
Post #19
mxcrazy wrote:
simonjames wrote:
i have the 290mm 406 v6 coupe rear disc, calipers i just need to trial fit then decide if i put the 406 drum for handbrake or alter the caliper somehow


Is it a single disc then and separate drum?


yeah iirc the disc sits over the drum

________________________________________

All South Wales Members Click Here
Team Supercharged Black RALLYE ™ (Click Here for Build Project)
MY EBAY ITEMS

07943066306
Posted 14th Apr 2010 at 03:51
Profile
miles

Seasoned Pro

Location: Ringwood

Registered: 28 Dec 2002

Posts: 3,433

Status: Offline
Post #20
You can fit vented and slightly larger ones off the shelf all Pug parts too,

________________________________________

306 Rallye Sptint/Race Car, 205 CTI 1.9 8v to name a few

Road, Track and Race/Rally car preparation to your personal requirements,
Full Workshop & Diagnostic Facilities
New and Second parts, from Plugs to Turbo's
We now also carry out Routine Servicing
www.pugracing.com

& FB Page, https://www.facebook.com/PugRacing

Ebay; http://stores.ebay.co.uk/Pug-Racing-Shop

2012/2013/2014/2019 Class Winners at Gurston Down Speed Hillclimb & Joint overall, Class record too along the way,
Posted 14th Apr 2010 at 07:29
Profile
simonjames

Seasoned Pro

Location: Whitland S.Wales

Registered: 23 Nov 2004

Posts: 6,219

Status: Offline
Post #21
using s16 front discs yeah?

________________________________________

All South Wales Members Click Here
Team Supercharged Black RALLYE ™ (Click Here for Build Project)
MY EBAY ITEMS

07943066306
Posted 14th Apr 2010 at 14:19
Profile
velar

Regular

Location: swindon

Registered: 04 Jan 2009

Posts: 448

Status: Offline
Post #22
Front discs on 306/406 are not very well vented, so overheat in track use.
I run an ex BTCC 406 coupe, with had standard 406 V6 discs (305mm) and they overheated within a couple of laps( with just a standard GTI6 engine.)

Upgraded the front discs to 324mm( with much better internal venting), and they now last over 25 laps with no heating issues.I can also get away with much cheaper brak pads( £50 a go instead of £120)

The standard 406 rear discs are 290mm but are really heavy due to the internal handbrake. I changed them to 280mm with Ap twin pot calipers, and use a brake balance bar on the car.

I am putting the same brake setup on the GTI6Roll eyes Roll eyes

________________________________________

L reg "black and blue" phase 1 track 6
Posted 19th Apr 2010 at 23:52
Profile
simonjames

Seasoned Pro

Location: Whitland S.Wales

Registered: 23 Nov 2004

Posts: 6,219

Status: Offline
Post #23
Ha i tried the 406 1s on today and they would need to be spaced out about 3-4 inches to fit so not gonna bother with them LOL

________________________________________

All South Wales Members Click Here
Team Supercharged Black RALLYE ™ (Click Here for Build Project)
MY EBAY ITEMS

07943066306
Posted 20th Apr 2010 at 00:45
Profile
MCH_GTi6

formerly mch

Location: Hayle

Registered: 09 Sep 2005

Posts: 2,456

Status: Offline
Post #24
miles wrote:
You can fit vented and slightly larger ones off the shelf all Pug parts too,


do tell Happy

________________________________________

Team Moonstone� Ph3 GTI6
Team Rallye
Posted 20th Apr 2010 at 00:51
Profile
Home -> Forums -> Brakes -> big rear discs

All times are GMT. The time is now 13:20

The Peugeot GTi-6 & Rallye Owners Club - ©2024 all rights reserved.

Please Note: The views and opinions found herein are those of individuals, and not of The Peugeot 306 GTi-6 & Rallye Owners Club or any individuals involved.
No responsibility is taken or assumed for any comments or statements made on, or in relation to, this website. Please see our updated privacy policy.