Brake up-grade options

General Chat About Brakes & Suspension

Moderator: phpBB2 - Administrators

bbutc
Newbie
Newbie
Posts: 8
Joined: Mon Aug 15, 2022 12:15 pm

Brake up-grade options

Post by bbutc »

Hello – New DAX Rush owner here.

I’m already thinking about upgrading the front single pot brake calipers to four pot calipers, but I need to know what vehicle the steering knuckles were sourced from. I’ve taken some photographs, here>

https://1drv.ms/u/s!AsRQ3YcdckUvhFvqGW2 ... K?e=yTdkg8
https://1drv.ms/u/s!AsRQ3YcdckUvhFgIm2- ... c?e=hT8SZc
https://1drv.ms/u/s!AsRQ3YcdckUvhFnhbwe ... b?e=b06vRP
https://1drv.ms/u/s!AsRQ3YcdckUvhFphSwY ... q?e=Ii0tbu

The vehicle was completed in 2012. If someone could identify the steering knuckles for me then I can do my own research.
Many thanks. Ben.



stevieturbo
Forum Contributor
Forum Contributor
Posts: 3979
Joined: Sat Nov 18, 2006 6:22 pm
Location: Northern Ireland

Re: Brake up-grade options

Post by stevieturbo »

9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

bbutc
Newbie
Newbie
Posts: 8
Joined: Mon Aug 15, 2022 12:15 pm

Re: Brake up-grade options

Post by bbutc »

Thanks Steve - lots of useful information there.

The car currently has 260mm front discs with single pot calipers, which feel under powered IMO.

Currently looking to replace them with a 283, 300 or 325mm 4 pot caliper kit.

If anyone has been down this route, then feel free to chip-in with advice.

Thanks.

scudderfish
Site Admin
Site Admin
Posts: 486
Joined: Sat Feb 28, 2009 6:53 pm
Location: Harpenden, Hertfordshire

Re: Brake up-grade options

Post by scudderfish »

Can you lock the fronts? It might be an idea to experiment with different pads/pedal ratio/cylinder sizes before going down an expensive route.

stevieturbo
Forum Contributor
Forum Contributor
Posts: 3979
Joined: Sat Nov 18, 2006 6:22 pm
Location: Northern Ireland

Re: Brake up-grade options

Post by stevieturbo »

bbutc wrote:
Wed Aug 17, 2022 2:01 pm
Thanks Steve - lots of useful information there.

The car currently has 260mm front discs with single pot calipers, which feel under powered IMO.

Currently looking to replace them with a 283, 300 or 325mm 4 pot caliper kit.

If anyone has been down this route, then feel free to chip-in with advice.

Thanks.
What exactly is the problem ? fade ? feel ? other ? Are they solid or vented ?

As Scudder says, even a pad change can make a huge difference.

HiSpec and no doubt countless others would offer direct bolt on kits.

Or Burton list various stuff

https://www.burtonpower.com/catalogsear ... t_limit=80

What wheel diameter do you run in order to increase diameter if needed ?
9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

User avatar
Ian Anderson
Forum Contributor
Forum Contributor
Posts: 2396
Joined: Sun Nov 19, 2006 9:46 pm
Location: Edinburgh

Re: Brake up-grade options

Post by Ian Anderson »

Owner of an "On the Road" GT40 Replica by DAX powered by 3.9Hotwre Efi, worked over by DJ Motors. EFi Working but still does some kangaroo at low revs (Damn the speed limits) In to paint shop 18/03/08.

bbutc
Newbie
Newbie
Posts: 8
Joined: Mon Aug 15, 2022 12:15 pm

Re: Brake up-grade options

Post by bbutc »

Hi Steve / Scudder - I'm afraid I've been spoiled in the brake department over the last 22 years as I've been driving Porsches, and even my daily drive has 4 pot Brembo's. I'm used to gently pressing the brake peddle with my big toe and the vehicle coming to a controlled stop. Any braking system that requires you to use your entire body weight to operate has room for improvement, IMO. My mates 1.6 Ford Fiesta has 260mm front discs with a single piston but the car's performance dons't really compare to a DAX Rush V8. There's nothing mechanically wrong with the current brakes - they are just under sized - brakes are also a safety feature, so any expense can be justified, although I'm not going to go mad - the vehicle is relatively light weight so there is less mass to stop.

Can you advise on the rear jacking points, as I want to examine the rear brakes, thanks.

User avatar
ChrisJC
Top Dog
Top Dog
Posts: 5039
Joined: Mon Nov 20, 2006 1:13 pm
Location: Northants / Cambs
Contact:

Re: Brake up-grade options

Post by ChrisJC »

If you can lock the fronts, and don't get brake fade, then the issue (as observed above) could well be an inadequate servo, or the relative sizes of master cylinder and slave cylinders.

Chris.
--
Series IIA 4.6 V8
R/R P38 4.6 V8
R/R L405 4.4 SDV8

scudderfish
Site Admin
Site Admin
Posts: 486
Joined: Sat Feb 28, 2009 6:53 pm
Location: Harpenden, Hertfordshire

Re: Brake up-grade options

Post by scudderfish »

If you don't have servo assistance, you'll never stop the car with just your big toe, it will always require a hefty shove. You can reduce the pressure on the pedal by going down a size on the master cylinder, which is mechanically similar to having a longer brake pedal; you'll push it less hard, but the pedal will move further.
Pedals, cylinders & calipers is just a case of geometry as to how much pressure you can apply to the pad against the disk (and at what distance from the centre of the wheel) Pads are like tyres, they do the actual work and a change in material can make all the difference to how the car feels and behaves.
I don't know the Dax chassis, but for jacking points I'd aim for load points such as where the suspension mounts or where tubes join. Just stay away from the centre of any length of tube.

stevieturbo
Forum Contributor
Forum Contributor
Posts: 3979
Joined: Sat Nov 18, 2006 6:22 pm
Location: Northern Ireland

Re: Brake up-grade options

Post by stevieturbo »

bbutc wrote:
Thu Aug 18, 2022 9:03 pm
Hi Steve / Scudder - I'm afraid I've been spoiled in the brake department over the last 22 years as I've been driving Porsches, and even my daily drive has 4 pot Brembo's. I'm used to gently pressing the brake peddle with my big toe and the vehicle coming to a controlled stop. Any braking system that requires you to use your entire body weight to operate has room for improvement, IMO. My mates 1.6 Ford Fiesta has 260mm front discs with a single piston but the car's performance dons't really compare to a DAX Rush V8. There's nothing mechanically wrong with the current brakes - they are just under sized - brakes are also a safety feature, so any expense can be justified, although I'm not going to go mad - the vehicle is relatively light weight so there is less mass to stop.

Can you advise on the rear jacking points, as I want to examine the rear brakes, thanks.
Is it a direct master, or is there a servo ?

It would seem more a major problem if you are having to press the pedal as hard as you describe to get some braking. That sounds like a fault and there is something mechanically wrong, not a lack of performance. It's a light vehicle, it should not need huge brakes.

Exactly what pads are in it at present ?

And number of pistons really doesn't affect performance that much. If the caliper is capable of locking the wheel, it clearly has enough force ability and almost any braking setup should be capable of that
9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

bbutc
Newbie
Newbie
Posts: 8
Joined: Mon Aug 15, 2022 12:15 pm

Re: Brake up-grade options

Post by bbutc »

Update on this - Noticed that the brake fluid was looking rather brown - don't think it's been changed for years. Should have checked this really - school boy error. Anyway too late now as the 4-pot calipers have been ordered. Going to change the front calipers and all the discs/pads and fluid and see how it feels. If I don't like the new calipers I'll just stick the old ones back on.

SuperV8
Guru
Guru
Posts: 947
Joined: Tue Jul 07, 2009 11:25 pm
Location: West midlands

Re: Brake up-grade options

Post by SuperV8 »

bbutc wrote:
Mon Aug 15, 2022 8:46 pm
Hello – New DAX Rush owner here.

I’m already thinking about upgrading the front single pot brake calipers to four pot calipers, but I need to know what vehicle the steering knuckles were sourced from. I’ve taken some photographs, here>

https://1drv.ms/u/s!AsRQ3YcdckUvhFvqGW2 ... K?e=yTdkg8
https://1drv.ms/u/s!AsRQ3YcdckUvhFgIm2- ... c?e=hT8SZc
https://1drv.ms/u/s!AsRQ3YcdckUvhFnhbwe ... b?e=b06vRP
https://1drv.ms/u/s!AsRQ3YcdckUvhFphSwY ... q?e=Ii0tbu

The vehicle was completed in 2012. If someone could identify the steering knuckles for me then I can do my own research.
Many thanks. Ben.
Hi Ben,
Fellow Rush owner here.
You have the Sierra front knuckle.

There is a Dax Rush forum - though it is a little quite these days:
https://forum.daxsportingclub.com/

How did you get on with your brake 'upgrade'? I know i'm a bit late to the party!

The common upgrade is Cosworth front discs (278) with a simple caliper spacer - which I thought it looked like you have from your pictures?
I agree the Rush brakes are different/heavy compared to any modern car - as they are NOT servo assisted. I generally find modern cars too assisted for my preference but agree braking in the Rush does need a strong leg.

I fitted the larger piston calipers which helped reduce the pedal effort - but I also had crap redstuff pads which didn't help! on the road they have too low friction coefficient - only when they start getting hot does the friction increase giving a better brake - You need a pad friction material which works from cold for a road car - especially one like the Rush without servo assisted brakes. Stay away from any pads saying they are fast road or race branded unless you are actual racing the thing - just can't get the heat into them for them to work effectively on the road in a light weight Rush.

You can get remote vacuum servo's which can mount anywhere which may be a simpler/cheaper route to lighter brake pedal.

Just to re-cap to increase your brake torque (lighter pedal effort) you can:
fit larger diameter discs - to increase the radius the pads act on
fit a larger piston caliper (at the expense of pedal travel)
fit higher friction coefficient pads
fit smaller piston master cylinder
Its actually the mean radius of the pads which dictates the brake torque - so you can grind away the inside radius of the pads - which moves the mean radius outwards giving more brake torque (at the expense of pad life) Pad surface area has nothing to do with brake torque.

Just fitting 4x piston calipers doesn't automatically increase the clamping force on the front discs if the piston/hydraulic force is unchanged.
On the Rush you can also fine tune the front/rear brake balance which might help.

Tom.
Dax Rush 4.6 supercharged V8 MSII

SuperV8
Guru
Guru
Posts: 947
Joined: Tue Jul 07, 2009 11:25 pm
Location: West midlands

Re: Brake up-grade options

Post by SuperV8 »

bbutc wrote:
Thu Aug 18, 2022 9:03 pm

Can you advise on the rear jacking points, as I want to examine the rear brakes, thanks.
I use my jack under the centre of the chassis (steel box tubes) infront of the diff - with a rubber pad.
Dax Rush 4.6 supercharged V8 MSII

stevieturbo
Forum Contributor
Forum Contributor
Posts: 3979
Joined: Sat Nov 18, 2006 6:22 pm
Location: Northern Ireland

Re: Brake up-grade options

Post by stevieturbo »

SuperV8 wrote:
Tue Jan 03, 2023 12:15 pm
Stay away from any pads saying they are fast road or race branded unless you are actual racing the thing - just can't get the heat into them for them to work effectively on the road in a light weight Rush.
Problem is, this is not always true.

One of the best cold bite pads I've used was the Carbon Lorraine RC8, which is a fairly full on race pad. However, brake dust and aggressiveness on the discs was pretty harsh. Their more road/track pad the RC6 was easier for brake dust, but still lacked cold bite I wanted for the road, which seemed odd. Although otherwise they performed well.

If you didn't very regularly clean the wheels, the dust would stick pretty solid ! And my wheels are awkward to clean.

Even on my own heavy car, I just went back to plain and simple Mintex 1155's. I've tried far too many pads over the years, often lacking in what I wanted. And oddly many pads just fall apart, material breaking up, coming away from the backplate etc.

Some of them have performed well in some areas, but lacking in others.

If it was a lighter car I'd probably just try the 1144's ( I use them at the rear )

Overall they work fine, so far they have not fell apart, and brake dust is pretty easy to clean up.

In many ways we have more pad choices than ever....that can be a good and bad thing
9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

SuperV8
Guru
Guru
Posts: 947
Joined: Tue Jul 07, 2009 11:25 pm
Location: West midlands

Re: Brake up-grade options

Post by SuperV8 »

stevieturbo wrote:
Tue Jan 03, 2023 1:05 pm
SuperV8 wrote:
Tue Jan 03, 2023 12:15 pm
Stay away from any pads saying they are fast road or race branded unless you are actual racing the thing - just can't get the heat into them for them to work effectively on the road in a light weight Rush.
Problem is, this is not always true.

One of the best cold bite pads I've used was the Carbon Lorraine RC8, which is a fairly full on race pad. However, brake dust and aggressiveness on the discs was pretty harsh. Their more road/track pad the RC6 was easier for brake dust, but still lacked cold bite I wanted for the road, which seemed odd. Although otherwise they performed well.

If you didn't very regularly clean the wheels, the dust would stick pretty solid ! And my wheels are awkward to clean.

Even on my own heavy car, I just went back to plain and simple Mintex 1155's. I've tried far too many pads over the years, often lacking in what I wanted. And oddly many pads just fall apart, material breaking up, coming away from the backplate etc.

Some of them have performed well in some areas, but lacking in others.

If it was a lighter car I'd probably just try the 1144's ( I use them at the rear )

Overall they work fine, so far they have not fell apart, and brake dust is pretty easy to clean up.

In many ways we have more pad choices than ever....that can be a good and bad thing
None of the fast road/race pads show friction coefficient vs temp graphs below 100degs! and there's a reason! because below 100 they are generally low.
Tribology is a massively complex subject and you have many opposing factors you're trying to balance/compromise - hot and cold friction is one - you can't have both whilst also preserving wear and noise.
Does your car have a brake servo? This will mask any low friction behavior.
I work in brakes and carry out many brake tests and agree there is much choice - however there is too much marketing BS to make an informed.
Dax Rush 4.6 supercharged V8 MSII

Post Reply

Return to “Brakes & Suspension Area”