Disc Brake Conversion - Moulded Discs

Nishan.dj · August 8, 2014

Hi Friends,

Please read this issue and comment what you know or experienced or heard about it. Thanks a lot in advance.

I was having this idea for a long time which is to convert 4DR5 Drum brakes to Discs but many people advised with many ideas that some says don't do it and some says do so. Actually one of my friend did it on front wheels sometime back and he is saying he has better braking especially when running in the city. ( Better means, sudden stops due to motor bikers and three wheelers in a traffic conditions )

However I think the common issue with these jeeps are is that, the vehicle is pulled to one side when braking hard. ( Especially when we want to stop suddenly when the speed is aroud 70 KMPH or higher)

To overcome this issue, I have pasted the drums and serviced the braking system ( From master pump to brake shoes, replacing washers and etc.. )

By doing that we can achieve a good level of braking without pulling to any side for sometime and again that issue comes. Then we have to get a mechanics help to adjust the brakes and this goes on and on.

I called several people who said to be experienced of doing such conversions and all of them quoted very different prices.

Some says they change the axles with ones with Discs and one person said, he does not change any axles but remove the drum and related parts and modify it with disc to match with Pajero caliper set. For that they say they get the disc Moulded from a place at Moratuwa or somewhere. However I inspected 2 jeeps they have done recently with the one of it is belonging to a friend of mine that I mentioned earlier. Those are seemed to be fine for me but I really don't know technically how successful that is in a long run.

Also I am having a free wheel hubs at front and as per they, any of those are not required to change and Discs can be applied without any problem. The amount they quoted for that is 55000 for front two wheels.

I am thinking of getting this conversion done may be in a month or two. So please advice any drawbacks you see on this. Also if you have done it before please post your experience. Its really valuable. Thanks again.

The Don · August 8, 2014

I recently learned a lot about disc brake conversions, while researching this topic for a car, but some of it is relevant to any vehicle.

In principle it is not very difficult for the front. What you do is;

1. source the discs, calipers from a similar vehicle

2. remove the drum brakes from the hub

3. modify the backing plate

4. Modify the hub and the sourced discs so that they fit into the hub. This sometimes require the machining of an adapter

5. Machine and create an adapter to attach the caliper to the axle/ backing plate

Apart from this you would need to do the following. The brake master cylinder has a spring loaded valve mechanism that keeps the pressure of the brake system at a certain level. This is so that the brake shoes/ pads are kept close enough to the drum/ disk so that when braking pedal movement is limited. This back pressure is different for drums and discs. I think its higher for drums so if you don't swap these when you change the front to discs for the front brake circuit you might get brake binding (I think, I don't remember which one was higher).

Nishan.dj · August 8, 2014

On 8/8/2014 at 10:13 AM, The Don said:
1. source the discs, calipers from a similar vehicle

In this case, they get Pajero calipers and moulding the disc. Not reconditioned or OEM discs.

On 8/8/2014 at 10:13 AM, The Don said:
2. remove the drum brakes from the hub
3. modify the backing plate

4. Modify the hub and the sourced discs so that they fit into the hub. This sometimes require the machining of an adapter

5. Machine and create an adapter to attach the caliper to the axle/ backing plate

I noticed that the moulded disc is thicker than an OEM disc that comes to any other vehicle.

On 8/8/2014 at 10:13 AM, The Don said:
The brake master cylinder has a spring loaded valve mechanism that keeps the pressure of the brake system at a certain level.

There are two hydraulic lines going from master cylinder to front and rear wheels but If the spring loaded valve is for master cylinder, could it be a problem? ( Don't know whether this booster has that spring loaded mechanism ).

The Don · August 8, 2014

On 8/8/2014 at 10:34 AM, Nishan.dj said:
In this case, they get Pajero calipers and moulding the disc. Not reconditioned or OEM discs.
I noticed that the moulded disc is thicker than an OEM disc that comes to any other vehicle.

There are two hydraulic lines going from master cylinder to front and rear wheels but If the spring loaded valve is for master cylinder, could it be a problem? ( Don't know whether this booster has that spring loaded mechanism ).

The spring loaded mechaism is inside the master cylinder. In dual circuit systems with two resovoirs its under the resovoir. Check if your system is a dual circuit or single circuit first. The solutions are different dependent on that. Dual circuit systems isolate the two lines for front and back so if one fails or leaks, the other will still function. Its a fail safe.

Nishan.dj · August 8, 2014

A single resoviour (oil tank) but two separate lines gone to front and back from the master cylinder. Hope that wouldn't effect if the disc conversion is done.

The Don · August 8, 2014

On 8/8/2014 at 3:45 PM, Nishan.dj said:
A single resoviour (oil tank) but two separate lines gone to front and back from the master cylinder. Hope that wouldn't effect if the disc conversion is done.

I think thats a dual circuit system. You may need to adjust the brake propotioning as well, but this is usually ok as most brake force is propotioned to the front anyway. Hopefully your mechanic knows what he is doing.

Nishan.dj · August 9, 2014

Thanks don.

Yes mechanically he seems to be good and done this type of conversions before. But my concern here is that they mould the discs to match with calipers and wheels. Have you come across such modifications while you were looking for that for your car?