| Author |
Message |
Maddward
Samba Member
Joined: July 18, 2010
Posts: 206
Location: Orange County, CA
|
|
| Back to top |
|
 |
oldschool5er
Samba Member
Joined: May 28, 2007
Posts: 804
Location: Ohio
|
 Posted: Fri Jan 04, 2019 9:19 am Post subject: Re: Do I have enough brakes? |
 |
|
One of your problems is you have a single piston caliper in the rear and a dual piston caliper in the front. Your bias also should be more to the rear brakes and less to the front. In offroad you do not want your front locking up before the rear, you want the brakes to pull down more on the rear. You lock the front up first you lose control over the steering.
That being said you should be able to lock your tires up at some point on pavement, but bias still adjusted to pull down on the rear first before locking up the fronts. You should be running a dual piston in the rear, at least they would match front to rear. Even if you had single piston in the front and dual in the rear you could focus on the stopping power more on the rear. At this point you might want to try a larger master cylinder. I see these problems all the time and I understand the cost of running good brakes front and rear so I see mismatched setups all the time.
I have had good luck with my 3 bajas because they are matched brakes. I run the Ghia ones like you have in the rear on my fronts also, and I can lock all 4 up with the stock dual chamber master cylinder and no residual valves used. The other two were cnc and Jamar both front and back matched.
I can only see a larger master and bias thrown to the rear that might make a big difference....might. Or put on dual piston CNC rear calipers, or put ghia single piston calipers on the front. Another longshot might be to keep the bias 50/50 and use a proportional valve, but I still think it won't help that much. CNC has a 1" master 702F-1 for like $75. They also have a dual master with one side 3/4 and the other 7/8". I also realize CNC if you call them, will want you to put their rears on at an very high price probably.
_________________
HRE in Westerville,Ohio
Full machine shop with all types of CNC. Rapid prototyping available, CNC Plasma cutting, 3D printing and Laser engraving. |
|
| Back to top |
|
|
Maddward
Samba Member
Joined: July 18, 2010
Posts: 206
Location: Orange County, CA
|
|
| Back to top |
|
|
oldschool5er
Samba Member
Joined: May 28, 2007
Posts: 804
Location: Ohio
|
| Posted: Fri Jan 04, 2019 10:08 am Post subject: Re: Do I have enough brakes? |
|
|
| Maddward wrote: |
Thanks oldschool5er
I can adjust the bias in my pedals with the bias rod. At one point I had most of the braking on the rear but I still couldn't stop fast enough. So I added more back to the fronts.
Would these calipers work ok with the 3/4 master? 4 piston (1.38") and for .38" rotor width which mine are. They're way cheaper than cnc calipers too
https://www.kartek.com/parts/forged-dynalite-four-...width.html |
I like the caliper, but the problem is volume as a 3/4" master might not have enough for 4 piston. If it did have enough volume to use a 4 piston on the rear I think the combo would work well. I typically try to keep front and rear matched but that is with use of a single master cylinder. You have two masters so 3/4" for the front, but maybe a 1" for the rear.
"UPDATE" I found the recommended size would be 7/8" for 4 piston calipers. But pedal length also will impact how much pressure you will have to use on the pedal.
_________________
HRE in Westerville,Ohio
Full machine shop with all types of CNC. Rapid prototyping available, CNC Plasma cutting, 3D printing and Laser engraving. |
|
| Back to top |
|
|
Maddward
Samba Member
Joined: July 18, 2010
Posts: 206
Location: Orange County, CA
|
|
| Back to top |
|
|
oldschool5er
Samba Member
Joined: May 28, 2007
Posts: 804
Location: Ohio
|
| Posted: Fri Jan 04, 2019 10:56 am Post subject: Re: Do I have enough brakes? |
|
|
I see that now, I didn't catch it on the cb performance picture.
_________________
HRE in Westerville,Ohio
Full machine shop with all types of CNC. Rapid prototyping available, CNC Plasma cutting, 3D printing and Laser engraving. |
|
| Back to top |
|
|
PhillipM
Samba Member
Joined: January 07, 2010
Posts: 595
Location: UK
|
| Posted: Fri Jan 04, 2019 11:25 am Post subject: Re: Do I have enough brakes? |
|
|
| If you can't lock either end and the pedal is hard, just switch down to a smaller master cylinder. Leverage is your issue. |
|
| Back to top |
|
|
Maddward
Samba Member
Joined: July 18, 2010
Posts: 206
Location: Orange County, CA
|
| Posted: Fri Jan 04, 2019 11:52 am Post subject: Re: Do I have enough brakes? |
|
|
I called CNC brakes and they recommend a 3/4 master for the front 2 piston calipers I have which is good for me. So I assume the rears are close enough to being right too. The only thing I didn't do is put new pads in all the calipers. I did rebuild them all once though but I put the old pads back in since they all had a lot of material left still. And I roughed up the rotors with 120 grit.
I see I can get more aggressive 2" wide pads for the cnc calipers, are there any available for the ghia calipers?
_________________
1959 Baja Bug, A-arm J30 Honda
https://www.thesamba.com/vw/forum/viewtopic.php?t=701787&highlight= |
|
| Back to top |
|
|
PhillipM
Samba Member
Joined: January 07, 2010
Posts: 595
Location: UK
|
| Posted: Fri Jan 04, 2019 12:04 pm Post subject: Re: Do I have enough brakes? |
|
|
What they recommend or not doesn't really matter, if you have a rock hard pedal and it takes a lot of force to stop and too much to lock, you don't have enough leverage.
Try a 5/8, should give you ~40% more power - it's what I used to run with very similar tiny wilwood 2-pots up front. And my rail is about the same weight and tyre sizes as your Baja. 3/4" might have been okay if you were running the longer pedals with more leverage.
You could try more aggressive pads but unless your are already all cooked you should be able to lock up at least at low speeds where heat isn't a factor.
On a street car you really should be locking the fronts just before the rears - you can feel the loss of steering and just ease off the brake a little - which is much easier than having to come off the brakes to catch the snap oversteer from the rear locking while you're trying to avoid someone that's pulled out on you, etc. |
|
| Back to top |
|
|
Maddward
Samba Member
Joined: July 18, 2010
Posts: 206
Location: Orange County, CA
|
| Posted: Fri Jan 04, 2019 3:03 pm Post subject: Re: Do I have enough brakes? |
|
|
Thanks PhillipM
I just went to a website where it explained bore area of master cylinders and calipers and how to choose them. So I did all the math and came up with needing 5/8 master cylinders just like you said. With my pedal ratio it will increase leverage from 24:1 to 35:1 (pressure by +44%). You were exactly right!
The site said a hard pedal and not enough stopping power was too large of a master cylinder, and a lot of pedal travel and not enough stopping power was too small of a master cylinder. I'll update this after I change out the master cylinders. Anybody need a pair of CNC 3/4 short master cylinders?
_________________
1959 Baja Bug, A-arm J30 Honda
https://www.thesamba.com/vw/forum/viewtopic.php?t=701787&highlight= |
|
| Back to top |
|
|
gilmarlin
Samba Member
Joined: September 16, 2019
Posts: 47
Location: LA MESA
|
| Posted: Mon Sep 16, 2019 9:34 am Post subject: Re: Do I have enough brakes? |
|
|
| This post was very helpful in pointing me in the right direction as to my very similar braking problem. I think I'll try a smaller master cylinder as my pedal is very hard and the brakes won't lock up even after servicing the rotors, pads and bleeding the system. Does anyone know where to get replacement O rings for 1 1/2" single piston CNC calipers? CNC is no more and like Tweed, just went out of business and left their customers high and dry. I'm sure the O rings they used had a part number... |
|
| Back to top |
|
|
Dal Churchill
Samba Member
Joined: November 10, 2008
Posts: 275
Location: Catalunya, Spain. Originally England UK.
|
| Posted: Mon Sep 16, 2019 1:41 pm Post subject: Re: Do I have enough brakes? |
|
|
All this talk of hard pedals made me wonder if anyone has ever fitted a servo to their Bug?
_________________
1974 Beetle. Bus/Porsche/Rover V8 (Buick 215ci) Baja. (Unfinished project)
1979 Beetle. 1641. Ex-Modern Day Luftwaffe Airfield Radio Car. (Daily driver) |
|
| Back to top |
|
|
jsturtlebuggy
Samba Member
Joined: August 24, 2005
Posts: 4496
Location: Fair Oaks/Orangevale, CA
|
| Posted: Mon Sep 16, 2019 2:27 pm Post subject: Re: Do I have enough brakes? |
|
|
Check with KarTek in Corona, they bought a lot of stock before CNC closed it doors.
_________________
Joseph
Fair Oaks/Orangevale, CA
Elrod Motorsports
Motion Tire Motorsports
Having fun with Dune Buggies since 1970
Into Volkswagens since 1960 |
|
| Back to top |
|
|
Cody Loren
Samba Member
Joined: April 23, 2018
Posts: 118
Location: Cucamonga ca
|
| Posted: Mon Sep 16, 2019 2:30 pm Post subject: Re: Do I have enough brakes? |
|
|
| How much are you asking for the 3/4 CnC masters? |
|
| Back to top |
|
|
jsturtlebuggy
Samba Member
Joined: August 24, 2005
Posts: 4496
Location: Fair Oaks/Orangevale, CA
|
| Posted: Mon Sep 16, 2019 7:55 pm Post subject: Re: Do I have enough brakes? |
|
|
If you are asking me about part prices, I am not selling any parts.
I was just recommending if he looking for piston seals for CNC brakes, that KarTek has a huge stock of CNC products including rebuild parts for CNC items.
_________________
Joseph
Fair Oaks/Orangevale, CA
Elrod Motorsports
Motion Tire Motorsports
Having fun with Dune Buggies since 1970
Into Volkswagens since 1960 |
|
| Back to top |
|
|
Vanillagurilla
Samba Member
Joined: November 21, 2017
Posts: 1061
Location: California
|
| Posted: Tue Sep 17, 2019 7:03 pm Post subject: Re: Do I have enough brakes? |
|
|
| I think he was talking to the OP who asked if anyone needs it. |
|
| Back to top |
|
|
Maddward
Samba Member
Joined: July 18, 2010
Posts: 206
Location: Orange County, CA
|
| Posted: Wed Sep 18, 2019 6:24 am Post subject: Re: Do I have enough brakes? |
|
|
Sorry, I don't have any CNC master cylinders for sale.
To bring this thread back up to date, I ended up buying rear 4 piston Tatum brakes for my car last week actually. And now I need a tall 7/8 CNC master cylinder to go with it! Hard to find now that they closed their doors
_________________
1959 Baja Bug, A-arm J30 Honda
https://www.thesamba.com/vw/forum/viewtopic.php?t=701787&highlight= |
|
| Back to top |
|
|
|
