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wbx
Samba Member
Joined: April 11, 2005
Posts: 1254
Location: Monterey, CA
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 Posted: Tue May 30, 2006 3:57 am Post subject: rear brake cylinder upgrade? |
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As some of you may know, i've been thinking about brake upgrades a bit, and was wondering if anyone has heard of a very simple rear cylinder upgrade? The stock is 23.81mm in diameter... If you bumped up to a 25mm or a 28.6mm cylinder, i'd imagine you'd have to have stronger brakes (the pads clamp harder agains the rims).
Anything bad that would happen here?
-Damon
_________________
'84 Westy (first owner).......but my daily driver has pedals
My "perspective" mantra:
A Volkswagen Vanagon is just a material thing,
As such, it is of the earth,
And if i need to, I can let my Van go. |
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Dogpilot
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Joined: October 03, 2005
Posts: 4205
Location: Flagstaff, AZ
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| Posted: Tue May 30, 2006 7:50 am Post subject: |
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Damon,
I think you would also have to replace the rear proportioning valve with an adjustable one. Otherwise, you might have rear brake lockup prematurely.
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Geology with a Syncro rocks!
86 Syncro Westy AKA "The Bughunter"
98 Disco I
08 Range Rover SC
08 VW Rabbit S
1951 O-1G |
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wbx
Samba Member
Joined: April 11, 2005
Posts: 1254
Location: Monterey, CA
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| Posted: Tue May 30, 2006 9:24 am Post subject: |
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| Dogpilot wrote: |
Damon,
I think you would also have to replace the rear proportioning valve with an adjustable one. Otherwise, you might have rear brake lockup prematurely. |
Very true, but the interesting thing is that the reason why a later model vanagon stops better is because they put better front brakes on. The rear is the same. So i'd imagine that would only be a concern for early model vans. The late front brakes have about 50% more stopping oomph (just based on some calculation estimates) than the earlier ones do. Seems like you could go 50% bigger area on the rear cylinders and have the same brake balance as an early model van, which German apparently thought was OK...
-Damon
_________________
'84 Westy (first owner).......but my daily driver has pedals
My "perspective" mantra:
A Volkswagen Vanagon is just a material thing,
As such, it is of the earth,
And if i need to, I can let my Van go. |
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walrus
Samba Member
Joined: June 02, 2005
Posts: 507
Location: ashland ky
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| Posted: Tue May 30, 2006 11:47 pm Post subject: |
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The rear brakes don't get used as much as the front. Hence the wear differance and the tendencey of manufacturers to use rotors on the front and drums on the rear.
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1987 Syncro west. conversion
1991 Jetta gli |
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wbx
Samba Member
Joined: April 11, 2005
Posts: 1254
Location: Monterey, CA
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| Posted: Wed May 31, 2006 4:54 am Post subject: |
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| walrus wrote: |
| The rear brakes don't get used as much as the front. Hence the wear differance and the tendencey of manufacturers to use rotors on the front and drums on the rear. |
Only kinda true. Front brakes definitely do more work in practice, but our vans are relatively rear heavy, and the rear brakes do disproportionately more work. On some cars, the rear pads wear out faster than the fronts, too. I also think rear drums are an economical choice for car manufacturers because it is "old" (read: cheap) technology, and you don't have to worry about a parking brake (either relatively expensive calipers, or a seperate drum e-brake mechanism).
What I was thinking was that you could simply bolt on a bigger rear cylinder to compensate for some sort of front brake upgrade. You don't just make the fronts infinitely powerful without doing something to the rears to compensate.
_________________
'84 Westy (first owner).......but my daily driver has pedals
My "perspective" mantra:
A Volkswagen Vanagon is just a material thing,
As such, it is of the earth,
And if i need to, I can let my Van go. |
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vwmaniaman
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Joined: June 07, 2005
Posts: 562
Location: Grand Rivers,KY
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| Posted: Wed May 31, 2006 5:35 am Post subject: |
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The volume of the cylinder is based on the boe size. The specific fluid output of the master cylinder would make a smaller say 22mm wheel cylinder apply more pressure to the shoes than a larger bore wheel cylinder.
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Working on a VW is like fun with a friend!
65 Beetle
75 Westy "Pumpkin Van"
86 Westy "Brown Betty"
87 Cabrio |
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wbx
Samba Member
Joined: April 11, 2005
Posts: 1254
Location: Monterey, CA
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| Posted: Wed May 31, 2006 6:40 am Post subject: |
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| vwmaniaman wrote: |
| The volume of the cylinder is based on the boe size. The specific fluid output of the master cylinder would make a smaller say 22mm wheel cylinder apply more pressure to the shoes than a larger bore wheel cylinder. |
Sorry... that's not true. Force=pressure * area. Increase the area/bore, you increase the force.
Smaller master cylinders equal bigger system pressure, but bigger wheel cylinders and caliper bores equal higher clamping force.
-Damon
_________________
'84 Westy (first owner).......but my daily driver has pedals
My "perspective" mantra:
A Volkswagen Vanagon is just a material thing,
As such, it is of the earth,
And if i need to, I can let my Van go. |
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walrus
Samba Member
Joined: June 02, 2005
Posts: 507
Location: ashland ky
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| Posted: Wed May 31, 2006 11:18 am Post subject: |
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I thought about the rear being heavy as I posted before but didn't mention it. From your first post it sounded as though you were wanting to upgrade the rear without doing the front.
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1987 Syncro west. conversion
1991 Jetta gli |
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[email protected]
Samba Member
Joined: March 07, 2004
Posts: 242
Location: Sunny AZ
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| Posted: Wed May 31, 2006 11:23 am Post subject: newbie brake question |
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Okay,
I've been reading all of these posts, and have a few basic questions.
I have an 85 westy.
Are the rear brakes on early/late vanagons the same?
Late vanagons (meaning 86>?) have 50% more front brake? How hard is it to upgrade from early to late? Or should I just upgrade to one of these big brake kits (that require 15" rims)?
thanks,
tom |
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wbx
Samba Member
Joined: April 11, 2005
Posts: 1254
Location: Monterey, CA
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| Posted: Wed May 31, 2006 7:50 pm Post subject: Re: newbie brake question |
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| [email protected] wrote: |
Okay,
I've been reading all of these posts, and have a few basic questions.
I have an 85 westy.
Are the rear brakes on early/late vanagons the same?
Late vanagons (meaning 86>?) have 50% more front brake? How hard is it to upgrade from early to late? Or should I just upgrade to one of these big brake kits (that require 15" rims)?
thanks,
tom |
As far as i can tell, yes. Rear brakes are unchanged for all model years.
First of all, late model front brakes, while better, are not amazingly better. Secondly, i have not done this, but i have put more than the average amount of thought into the vanagon braking system.
Mainly what you need are rotors and calipers. To do things right, though, you also need the late model uprights (same casting as early model, but different machining). I think you'd also need new brake lines as well. All that is not cheap for an incremental improvement in braking.
Several of us are working on upgraded brake systems independently, and have early model vans. If you don't mind waiting for a bit, i'm sure someone will post a result in not too long.
_________________
'84 Westy (first owner).......but my daily driver has pedals
My "perspective" mantra:
A Volkswagen Vanagon is just a material thing,
As such, it is of the earth,
And if i need to, I can let my Van go. |
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[email protected]
Samba Member
Joined: March 07, 2004
Posts: 242
Location: Sunny AZ
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| Posted: Thu Jun 01, 2006 9:07 am Post subject: thanks for the info |
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thanks for that brake summary. Yes, I'm planning on waiting until somebody post results on their brakes.
I'm focusing my energy and money (mainly money!) on the engine I'm building. |
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tencentlife
Samba Member
Joined: May 02, 2006
Posts: 10077
Location: Abiquiu, NM, USA
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| Posted: Thu Jun 01, 2006 9:30 am Post subject: |
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So hey, Damon, how is that big-disc brake development coming? I've perused the thread some, but my eyes start to swim in all the minutiae of different models and knuckles and calipers, and that's sayin' something, what with the length of MY typical posts! I've just been waiting to see if you're going to publish a parts list for us, so maybe I can assemble a kit myself. And are you just working on something for earlier vans, or do you think your results will encompass later bricks like my '87? Cause I'd sure like more stopping power, with the way we drive around here (far, and FAST!). I just put so much dough into the motor so I can GO, I'm having trouble with the idea of another $700 so's I can STOP!
Thanx for going to the trouble, though,
Chris |
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r39o
Samba Polizei
Joined: May 18, 2005
Posts: 9800
Location: San Diego
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| Posted: Thu Jun 01, 2006 10:59 am Post subject: |
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I suppose you could go to the next size up cylinder and the heaftier SA rear drums. (Is there an Audi (finned?) drum that would work?) It is not the backs that warp, though. The adjusters seem not to work so well. So your rear brakes don't do as much as they should in many cases. So I am ditching the rears for discs even though you don't gain anything much but they are easier to service and will not have the adjustment issues. With the front calipers I am using, I will not have to change my brake bias. All good things....
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"Use the SEARCH, Luke" But first visit the Vanagon FAQ!
1990 Multivan EJ 22, Rancho trans 0.82 4th, Small Car front AC, CLKs w/ 215/65-16, homemade big brakes 303mm, Konis, Recaros, etc....
Click to see my ads for Cup holders, Subaru clutch fix and CLK wheels (no wheels currently) |
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wbx
Samba Member
Joined: April 11, 2005
Posts: 1254
Location: Monterey, CA
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| Posted: Thu Jun 01, 2006 11:42 am Post subject: |
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| tencentlife wrote: |
| So hey, Damon, how is that big-disc brake development coming? |
Hi Chris,
For me? The brake project is non-existant. I am currently living in Ecuador, and my theoretical question inspired a lot of discussion. It won't be until June that i'll actually start to get my hands greasy. However, through discussions with wellington, r39o, and loogy, I have a really good idea of the direction that i am going. I won't go into details (well, they've all been gone into in that other thread), but yes, i am focusing on early model vans as they are often neglected in the big brake upgrade. However, anything that could work for an early van would easily work for a late model van with only the most minor modifications (and extra washer, or something).
Loogy and r39o are definitely the furthest along on the whole process. I just post pretty pictures. 
-Damon
_________________
'84 Westy (first owner).......but my daily driver has pedals
My "perspective" mantra:
A Volkswagen Vanagon is just a material thing,
As such, it is of the earth,
And if i need to, I can let my Van go. |
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Wellington
Samba Member
Joined: September 21, 2004
Posts: 1884
Location: Montreal
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| Posted: Thu Jun 01, 2006 12:18 pm Post subject: |
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| Ya I'll be doing just the front, but do you think I can find the G-60 calipers?!!!!!! That is my stumbling block. The rest should be strsaight forward. |
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r39o
Samba Polizei
Joined: May 18, 2005
Posts: 9800
Location: San Diego
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| Posted: Thu Jun 01, 2006 12:53 pm Post subject: |
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Well,
You can use the Corrado "G60" calipers too. They are just a single puck, though, but everything else is the same. The dual pot calipers are an upgrade to many other VWs. Hence you should be able to get the calipers that are replaced. I was able to get a set of the dual pot calipers, so I got some. Keep calling the Audi places, you are bound to find a set sometime, just like I did, if you really want those.
-Walt
_________________
"Use the SEARCH, Luke" But first visit the Vanagon FAQ!
1990 Multivan EJ 22, Rancho trans 0.82 4th, Small Car front AC, CLKs w/ 215/65-16, homemade big brakes 303mm, Konis, Recaros, etc....
Click to see my ads for Cup holders, Subaru clutch fix and CLK wheels (no wheels currently) |
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wbx
Samba Member
Joined: April 11, 2005
Posts: 1254
Location: Monterey, CA
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| Posted: Thu Jun 01, 2006 6:10 pm Post subject: |
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| Wellington wrote: |
| Ya I'll be doing just the front, but do you think I can find the G-60 calipers?!!!!!! That is my stumbling block. The rest should be strsaight forward. |
He Wellington. Honestly, if you are doing just the front, I don't think you want the "G-60" calipers. They have a smaller effective bore than the late model vanagons. Look at some BMW calipers that have the same 60mm bore as vanagons. Couple that with some 288x25 rotors, and you should be feeling pretty good about your stopping power!
-Damon
_________________
'84 Westy (first owner).......but my daily driver has pedals
My "perspective" mantra:
A Volkswagen Vanagon is just a material thing,
As such, it is of the earth,
And if i need to, I can let my Van go. |
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r39o
Samba Polizei
Joined: May 18, 2005
Posts: 9800
Location: San Diego
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| Posted: Fri Jun 02, 2006 1:02 pm Post subject: |
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Oops...sorry, another BF...I am getting old
_________________
"Use the SEARCH, Luke" But first visit the Vanagon FAQ!
1990 Multivan EJ 22, Rancho trans 0.82 4th, Small Car front AC, CLKs w/ 215/65-16, homemade big brakes 303mm, Konis, Recaros, etc....
Click to see my ads for Cup holders, Subaru clutch fix and CLK wheels (no wheels currently) |
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