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titan3c
Samba Member
Joined: February 16, 2012
Posts: 568
Location: Coweta, Oklahoma
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 Posted: Mon Feb 13, 2017 2:45 pm Post subject: Rear disc brake conversion |
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| Can't find a thread for this. Is there a rear brake disc brake conversion kit? Bob |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Mon Feb 13, 2017 4:32 pm Post subject: Re: Rear disc brake conversion |
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Yes and no. I have spoken briefly about it in the type 3 rear disc brake thread.
There is no kit made for type 4. However....type 4 uses all type 3 components.....hub, backing plate, hardware, shoes, cylinder ......except for the outer bearing cover and the stub axle.
However since it uses type 3 drum and backing plate.....the type 4 stub axle has the same spacing dimensions....and should have the same center ring diaketer to fit through the hole in the stock drum......and while the type 4 uses a bearing cover that is a 411 part #......the bolt pattern is the same as type 3.
So.....type 4 should be able to use a rotor and caliper from an aftermarket brake kit. I will be working on this in spring.
A little more information. Looking at the kits on the market for type 3.......my issue is that I am not willing to spend....$$$.....if my car will not use some of the major parts. Many of these seem to come with stub axles.....which we cannot use.
This leads me to believe that the rotors that come with these kits.....do not have the same size center opening. I have not had time to verify this. Also.....it is 100% unlikely that we will be able to use the e-brake cables that come with these kits.....and will have to extend or fab something from what we have.......so based on the fact that the ONLY parts in any kit we can actually use are the caliper, bracket and "possibly" the rotor......I am not willing to pay to find out what works and tjrow half of it away.
That being said....the CB performance cast steel caliper bracket should bolt right up. Whether it is the right thickness to operate between our outer bearing cover and the axle casting.....I do not know. It would have to be the EXACT thickness of the ecisting type 3/4 brake backing plate. If it is not....either it can be machined.....or the outer bearing hub can be machined. These can be had singular from several companies for about $80 each.
With some spacer work.....probably the calipers they offer can be used....or calipers from a Jetta 3 or 4 can be slaved on. We can get these calipers salvage and revuild them or new or rebuilt from Rockauto.
Either the rear rotor from Saab 900 or 914 is close.
I have also been thinking of using the caliper bracket mentioned...and use a caliper just like is on the front of the car or from a super beetle.....and make an extra bracket to hold a Wilwood mechanical parking brake caliper to hook to the E-brake cable. Ray
Ray |
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titan3c
Samba Member
Joined: February 16, 2012
Posts: 568
Location: Coweta, Oklahoma
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| Posted: Mon Feb 13, 2017 7:56 pm Post subject: Re: Rear disc brake conversion |
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| OK thanks---so there is more involved than I thought. Type 4 has good brakes, so now I wonder what would be the advantage of converting to rear disc? Bob |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Mon Feb 13, 2017 8:29 pm Post subject: Re: Rear disc brake conversion |
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| titan3c wrote: |
| OK thanks---so there is more involved than I thought. Type 4 has good brakes, so now I wonder what would be the advantage of converting to rear disc? Bob |
Better brakes for one....do not believe those who say there is no benefit. I have NEVER seen a PROPERLY done and optimized rear disk brake conversion that did not deliver better stopping power.
Optimizing means that you may need to reset front to rear brake bias. You "may" need a larger master cylinder (not in our case)...you will for sure need proper adjustable brake pressure regulation.
You will usually need to make a few adjustments to suspension stance or weight loading to make sure that the weight stays on the rear wheels for longer to take advantage of better braking before lock up during the forward inertial shift.
That can be accomplished with a combination of slightly larger than stock tires...a great investment either way....and the twin sway bar set up in the rear.
The other issue...is that the factory brake pressure regulator...which until last week I thought was unobtanium....but is still $200 and only available rebuilt from PMB performance....will be replaced with a simple adjustable aftermarket one that is roughly $75
Also....no more adjusting. When you drive a 411/412 in heavy traffic with high speeds in hot weather...you need to adjust about every 3 weeks on average.
Also quality German two piece rear drums are unobtanium. Only crappy cast Barzilian which are terrible. Ray |
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titan3c
Samba Member
Joined: February 16, 2012
Posts: 568
Location: Coweta, Oklahoma
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| Posted: Tue Feb 14, 2017 6:37 am Post subject: Re: Rear disc brake conversion |
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| Ok, I get your point, and I'm convinced that a rear disc brake conversion is a good thing. I'll be interested in knowing how you do it on your car. Bob |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Tue Feb 14, 2017 6:58 am Post subject: Re: Rear disc brake conversion |
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| titan3c wrote: |
| Ok, I get your point, and I'm convinced that a rear disc brake conversion is a good thing. I'll be interested in knowing how you do it on your car. Bob |
If funds are available.....its one of those projects I have had in mind for a while. Since I have a spare set of trailing arms.....I have been maing lists of parts ro rebuild them. I qm jot done with the front end yet and its final paint and undercoat are stalled by cold weather......so possibly in the next month I will start the trailing arms.
At least I will be buying most probably the CB performance caliper bracket. I will buy one first so I can start a thread on how the bracket even fits and what work is needed to the bearing cover if any.
Then I can publish the spacing...what calipers fit etc. At that point in time I will either like it.....or in the mean time I am watching Ateraxia on the type 3 forum who is doing an install on the CSP brand kit. Ray |
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Chris Walden
Samba Member
Joined: June 03, 2010
Posts: 147
Location: Indianapolis, Indiana
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| Posted: Tue Feb 14, 2017 6:56 pm Post subject: Re: Rear disc brake conversion |
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| How about 914 rears? |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Tue Feb 14, 2017 9:04 pm Post subject: Re: Rear disc brake conversion |
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| Chris Walden wrote: |
| How about 914 rears? |
I thought about those a long time ago. Too many issues....
1. The only reliable place to get them is PMB Performance...or have cores and buy their rebuild kits. The reman calipers are $300 a pair.
2. They only have 32mm pistons and pad size that is no larger than the front. In this respect they have a lot less swept area than the drum brakes.
3. They were just "adequate" for the 914.
The jetta 4 calipers are 38mm...and even though they are single piston sliders....they have a much larger swept area of pad.
Or...if you had REAL money  914-6 rear calipers have 38mm pistons.
The 914 calipers would largely return the same level of braking as the drums...but with a lot more convenience...but a large price to pay, you still need to fab a bracket or make mounts to fit a bracket kit.
For a long time I thought that the 914's might be the only way to go for a two piston caliper....but after seeing calipers like Jetta mk 4....sliders have gotten so good I am not adverse to using them.
If I can find a mechanical parking brake (I have found several from Wilwood)...it would be worth using a front caliper with its 42mm pistons.
Or I think the Super beetle caliper has 38mm pistons.
Lots to look at, Ray |
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