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SixtyThreeRag
Samba Member
Joined: July 12, 2015
Posts: 101
Location: Fort Worth, TX
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 Posted: Tue Jan 16, 2018 11:14 am Post subject: 4 wheel disc upgrade |
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Is it possible to stop on a dime with 15" wheels running 185's on the front and 195's on the rear?
I've got stock font disc/rear drum at the moment and they seem to lock up to easily. I feel like I need more braking power and better modulation. What's the best out there for street car use?
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Max Welton
Samba Member
Joined: May 19, 2003
Posts: 10697
Location: Black Forest, CO
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| Posted: Tue Jan 16, 2018 11:29 am Post subject: Re: 4 wheel disc upgrade |
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Is the problem mostly with the front?
Things that can make lock-up more likely:
To much pressure. What PSIs are you running front and back?
Shorter than stock tires. A smaller tire OD gives the brakes more "leverage" on the tread / road surface. Stock brakes are designed for stock-height tires. What profile are your 185s and 195s?
Smaller contact patch. Your 185s (almost any profile) should offer enough contact on the road to be sufficient. But people running tiny fronts because their car is slammed can have contact patch issues.
Max
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SixtyThreeRag
Samba Member
Joined: July 12, 2015
Posts: 101
Location: Fort Worth, TX
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| Posted: Tue Jan 16, 2018 11:35 am Post subject: Re: 4 wheel disc upgrade |
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| Max Welton wrote: |
Is the problem mostly with the front?
Things that can make lock-up more likely:
To much pressure. What PSIs are you running front and back?
Shorter than stock tires. A smaller tire OD gives the brakes more "leverage" on the tread / road surface. Stock brakes are designed for stock-height tires. What profile are your 185s and 195s?
Smaller contact patch. Your 185s (almost any profile) should offer enough contact on the road to be sufficient. But people running tiny fronts because their car is slammed can have contact patch issues.
Max |
I've got a 2" narrowed beam on it. The tires are 55 series. I run the tires at about 25 psi.
I've recently installed a proportioning valve as well to help bias the front/rear braking power since the front seems to lock up too early and it helped a but but I'm still not satisfied with it. |
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Max Welton
Samba Member
Joined: May 19, 2003
Posts: 10697
Location: Black Forest, CO
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bhartwell59
Samba Member
Joined: December 28, 2014
Posts: 791
Location: dallas, tx
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| Posted: Tue Jan 16, 2018 11:45 am Post subject: Re: 4 wheel disc upgrade |
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| SixtyThreeRag wrote: |
| I've got stock font disc/rear drum at the moment and they seem to lock up to easily. I feel like I need more braking power and better modulation. What's the best out there for street car use? |
I'm interested in this too... my front disc's do lock up sometimes.
I run 20/front 28/rear
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c21darrel
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Joined: January 22, 2009
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Location: San Dimas
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Max Welton
Samba Member
Joined: May 19, 2003
Posts: 10697
Location: Black Forest, CO
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| Posted: Tue Jan 16, 2018 4:39 pm Post subject: Re: 4 wheel disc upgrade |
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Also check the adjustment on the rear drums. Snug them right up. They need to be doing their part.
When the brakes lock, the fronts should lock first. But the rears should be very very close to locking.
I've been known to grab some e-brake to get some extra rear brake action in certain circumstances. 
Max
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1967 Type-3 Fastback
Under the Knife https://shoptalkforums.com/viewtopic.php?f=24&t=151582
Home Stretch https://www.thesamba.com/vw/forum/viewtopic.php?t=767836 |
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slalombuggy
Samba Member
Joined: July 17, 2010
Posts: 9145
Location: Canada
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| Posted: Tue Jan 16, 2018 5:18 pm Post subject: Re: 4 wheel disc upgrade |
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What are you running for shocks on your car? If you are using standard oil shocks in the fronts and the fronts are the ones locking up you could try putting a soft gas shock like a KYB GR-2 shock in to slow down the rear to front weight transfer under braking.
brad |
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VeloMikey
Samba Member
Joined: March 19, 2012
Posts: 651
Location: So Cal
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| Posted: Tue Jan 16, 2018 6:04 pm Post subject: Re: 4 wheel disc upgrade |
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I have Wilwood calipers on all four coners with stock style Ghia rotors on the front and Empi rotors on the rear. It is disappointing for the money you will spend. I wanted to go with Type III brakes but to do it right was over $1000 to piece it all together from ISP West and the Old Speed kit was $1250 with out E Brake cables. I have a dual circuit master and stainless soft lines too. I would search the classifieds for complete Type III brakes and try that out first. You can always resell it and go for the discs if you don't like the stopping power.
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TDCTDI
Samba Advocatus Diaboli
Joined: August 31, 2013
Posts: 12850
Location: North Carolina
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| Posted: Tue Jan 16, 2018 6:16 pm Post subject: Re: 4 wheel disc upgrade |
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The off-road guys use the larger front drum wheel cylinders in the rear to increase rear brake bias & this method is also used in conjunction with the larger type III shoes & drums.
Wheel cylinders are pretty cheap.
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Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.
GOFUNDYOURSELF, quit asking everyone to do it for you!
An air cooled VW will make you a hoarder.
Do something, anything, to your project every day, and you will eventually complete it. |
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sputnick60
Samba Moderator
Joined: July 22, 2007
Posts: 3916
Location: In Molinya Orbit
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| Posted: Tue Jan 16, 2018 7:45 pm Post subject: Re: 4 wheel disc upgrade |
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| TDCTDI wrote: |
The off-road guys use the larger front drum wheel cylinders in the rear to increase brake pressure in the rear & this method is also used in conjunction with the larger type III shoes & drums.
Wheel cylinders are pretty cheap. |
That effectively rebalances the brake bias for the rear and makes them work a little harder. That’s important I have learned. My previous Ghia, a 61 coupe, came to me with added front disks and drum rears. That car would regularly let go at the front because the rears weren’t working hard enough. It didn’t matter the profile size at the front, it was a badly engineered set up and dangerous in the wet. I wasn’t going put up with that for long.
A different situation goes for the CSP four wheel disk set on my current Ghia. You get a larger MC in that setup to match the increased pressure disk calipers need and not have excessive pedal pressure. I’ve found stopping in urban areas, where pedestrians, cyclists and parked cars sometimes jump into your path, is never a problem with the CSP brakes and performace is equally as good as modern cars. Mine has 185 profile tyres all the way around. CSP are more expensive than many are willing to pay but all the engineering is done and it comes with TÜV certification. So its built to meet a standard. I guess that’s where the extra expense is justified.
Nicholas
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Last edited by sputnick60 on Thu Jan 18, 2018 5:41 pm; edited 1 time in total |
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Max Welton
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Joined: May 19, 2003
Posts: 10697
Location: Black Forest, CO
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