The missing manual — Fitting a CSP disc brake kit to a VW T2
I recently fitted a CSP disc kit to my 1970 VW Bus, it was a relatively straight forward process but a few things caused me some issues along the way. As there’s not a huge amount of information about doing this conversion out there I thought it might help another first timer!
This is not a how to manual, it just fills in some of the gaps I ran into when I put them on, it’s important to do your own research for your own personal safety.
Understand what you’re getting into
My first piece of advice is to read the manual front to back and do some research on your current setup. For example, it’s important to understand what master cylinder you have, you have the tools you’re going to need before you start pulling things apart. With brake jobs, don’t start something you can’t finish… Nobody wants to be stuck with a bus that you can’t drive.
Master cylinder
Both the manual and the retailers give some slightly contradictory information.
The manual suggests you always need to change your master cylinder, the retailers say this is only the case for split screen buses. “Please note: When fitting this kit to a Split Screen T2 you will need to upgrade the master cylinder to a dual circuit unit.”
If you have a bay window bus with an existing dual circuit master cylinder you do actually have some work to do which isn’t mentioned by the retailers or in the the manual, but you don’t need to replace your master cylinder.
Residual pressure valves
A residual pressure valve is a essential for drum brakes, it maintains a small amount of pressure in the brake system. When changing to discs keeping this could cause the wheels to lock up or have the same result of driving with the pedal partially depressed.
If you are reusing your existing dual circuit master cylinder you need to remove the residual pressure valves from the front brake outputs on your master cylinder. On an early bay you will see your master cylinder has two outputs in a “V” formation at the back and one in the middle. The two at the back are for your left and right front brakes. The residual pressure valve is the part circled in yellow, it fits between the brake line and the master cylinder.
You have two options here, either you pull out the existing valve and strip it down to remove everything but the bolt, or you buy an adaptor. If you choose to strip it down they cannot be reassembled so I chose to buy two adaptors in case I ever wanted to go back to drum brakes.
If you are changing your master cylinder to a late type (for a splitscreen or perhaps you need a new one for your early bay) the inverse might be true, you may need to add an inline residual pressure valve for your rear drums. Consult your suppliers on this as some kits will come packaged with one.
Do this job first
I delayed this part of the job because I was waiting on these brake hose adaptors to arrive, so I had my entire kit fitted for a couple of weeks before touching the master cylinder. However I really wish I had waited.
When it came to removing the brake lines from my existing master cylinder I found myself in trouble, they had seized and no combination of WD40, PB Blaster or elbow grease could shift them. Frustration got the better of me and I ended up snapping the brake line which unfortunately led to needing to replace all the hard lines for the front brakes. This was not a position I wanted to be in as I’d never done this job before and set me back quite a few days.
So my suggestion would be to at minimum check your brake lines going into your master cylinder to make sure you can easily undo them before starting anything. If you can’t shift them and you don’t feel confident about replacing the hard lines if something goes wrong then it’s probably the time to book in this job with a professional VW garage.
Calliper mounting bracket bolts
The calliper mounting bracket attaches to the spindle with 2 hex bolts. These bolts will not go in as easily as the bolts you’ve removed from your drum backing plate. This is no doubt due to a bit of wear on your original bolts and the threads on the spindle.
I decided to “risk it” and simply try and turn down these bolts to the correct torque spec and unfortunately totally mashed the heads beyond repair and needed to get a new set sent from CSP. This is very tricky at the moment as they don’t ship low value items to the UK and these bolts are not available form any UK supplier. Shout out to Machine7 for helping me out with a special order on some replacements.
It was suggested to me I should use a special hex socket with a guide pin as this was the correct tool for the bolt spec. When I bought one of these it worked and I was able to torque these bolts down. Although this socket was a nice addition to my ever growing tool box and seemed to hold the bolt in place better this was not the reason I was able to torque them down. The bolts that I had mashed had actually cleaned the threads out enough for a new bolt to go in cleanly.
So this issue was entirely down to my poor prep, I should have chased the threads on the spindle. When you put these bolts in, if you have major resistance when trying to reach torque do not push any harder and spend more time cleaning the threads.
Spindle / hub bolt for bay windows
After setting up the hub / disc combo with new bearings, grease, seal and mounting on the spindle it gets held in place with the spindle nut.
On a split screen this is done with two nuts, locked in place with a tabbed lock washer bent over each nut. On a bay window this is a single nut held in place with a hex bolt.
Because the CSP kit has a small 4mm offset, the nut will not go onto the spindle the whole way as pictured below.
I wasn’t happy with how this looked, assuming this was incorrect I spent a bit of time making sure the bearing was seated correctly and putting it back on the spindle a few times.
After asking the VW community for advice I got a mix of responses. Some people said you couldn’t use these nuts with this kit, others suggested it was an incompatible spindle. I considered switching to the split screen 2 nut set up but after speaking to CSP they assured me that even though this looks wrong, it is in fact correct and expected. The part of the nut that’s doing the work to hold the hub in place is seated firmly and locked in onto the spindle.
Brake pad calliper assembly
There is almost no guidance in the manual about fitting the pads, it’s probably such a common task for professionals that this isn’t something they need to put in. However there is so much conflicting guidance out there about how to grease pads and calliper parts I found it best to watch multiple videos and read multiple threads about it. One person will tell you they use copper grease for everything, another will tell you to absolutely never use copper grease on brakes at all.
I decided to use a mixture of different greases for each part of the calliper assembly. Kits that contain small tubes of grease for the pin, clips and pads are available. I also used red rubber grease on the calliper mounting pistons.
Bearing races
The CSP kit comes with each matched bearing race already installed into the hub / disc combo so you don’t need to worry about this when installing.
Down the line if you need to change your wheel bearing it’s valuable to know that these cannot be removed with a punch as you might have previously done with a brake drum. They require a race removal tool to get out (or if you’re feeling brave apparently a few small welds to the race surface will cause them to pop out).
Outcome
After running this kit in for a couple of hundred miles I’m very happy with the results. However one thing to be aware of when fitting it is that although it does increase your stopping power and reduce brake fade it does not give you a modern “feel”. The pedal feels very hard and requires the same amount of force as the original drums, potentially more.
If you want to make the pedal feel better and increase stopping power with less effort it could be beneficial to fit a brake booster / servo to your drum set up before making the jump to discs. I am planning to add one to this set up in the near future.
Wrapping up
All in all, the kit is straight forward enough to do at home, these are just a few small things that stopped me in my tracks as this was my first time working with discs.
With any brake job, I recommend only doing this yourself if you are confident you can take it on. This is not something you can afford to get wrong and at any point where you feel uncomfortable I suggest calling in a professional. This blog is just for advice related to my personal experience of fitting this kit, it’s important to do your own research.
