Here in Oz Toyota 4 spots are a popular conversion
There are two types of caliper that will just about bolt straight onto the mopar mounts. Not sure about the âBâ body here but definitely âAâ bodies and OZ Valiant stuff.
A) To start with the calipers found on the FJ/HJ or 60 series Landcruiserâs are suitable. Also used on some model Hiluxâs. This is a 4 spot caliper that has two different sized pistons and some cooling fins. The leading piston is smaller than the trailing one i.e. two small opposing and two big opposing pistons.
B) The second suitable style are the ones used on the Toyota HZJ75 series prior to about 95â I think. This is about 20% bigger than the ones above. The difference is that it has 4 pistons of the same size, which makes it longer and hence a bigger pad.
Note: Both of these are available new from Vealeâs for a reasonable price. Second hand they can be bought very cheap. Overhaul kits are also available for both also very cheap. The smaller caliper is the better for straight replacement. The larger one really needs some brake proportioning work depending on what sort of booster your Chrysler is running standard. Donât get me wrong it will work brilliantly but rear drum brakes may lock in emergency stops (pretty par for course actually). My booster is quite weak due to M1 single plan manifold, so the old right boot does the work and the bigger brakes work well. There is a large range of pads so experiment here too. The big plus is that you have a platform to improve the whole braking system from here on. The most noticeable change is the brakes wonât pull on either side first, it is very even and you are not fighting to keep the car in a straight line. You have a lot more feel and can therefore go harder on the pedal.
Here is what you need to do. It may sound fiddly but it is all a piece of cake.
1) Find a pair of Toyota 4 spot calipers. Remove your old Chrysler calipers and do a quick mount up to see what your up against. They bloody well almost bolt straight on but you will need to do a couple little things so they look and work like factory ones.
2) Send your disks (the vented style) off to the brake shop and have them skimmed around 3 mm off the outer radius. NOT thickness, the outer diameter of the disk needs to be reduced so it doesnât touch the caliper. Some vals are different which is where the quick fit check prior to skimming pays off. Do some quick eye-balling of your own. Mine was a small bolt pattern vented disk set-up ala Dart/VG.
3) Whilst thatâs being done. New or old you will need to split the calipers apart. Simply four bolts. Whilst they are separated you need to open up the central rotor slot by about 2-3 mm on each side. Probably donât need too if using a solid rotor, but go the vented ones whilst your upgrading. I used a smaller angle grinder with a thicker cutting disk rather than a grinder disk. Cutter disks donât like sideways force so donât rush it, take your time and use safety goggles. The Chrysler vented (or brand new DBA slotted disk if you choose) disk will now happily fit in them.
4) Okay. The Toyota stuff is metric so a couple little mods must be done here. The caliper bolt holes are a little bigger than the Chrysler caliper bolt holes. The simplest thing to do here is fit a sleeve between the standard imperial bolts from you old brakes and the new caliper. Thus retaining mounts and retaining bolts. I used some copper pipe pressed with my vice into the caliper holes and then filed out for a neat fit. Then I notice that Suzuki Sierra locating dowels, between the engine and gearbox, are a perfect fit. This is what I used on my second conversion. Clean up either side with the grinder so itâs flush.
5) Thoroughly clean the calipers and join back together. No sealant is required. Just REMEMBER the âOâ ring seals. Paint them what ever colour you want. I recommend VHT caliper paint here.
6) Homeward bound now. One more critical thing to do, but also very easy. Take your flexible brake line, the one that goes from the chassis to the caliper, to a hose specialist (Perth Brake Supplies, Welshpool) and get two new braided steel lines made. The chassis end needs to retain the 3/8? NPT thread BUT the other end needs to be a 10 mm i.e. the same as the Toyota metric thread. It will be a banjo style with bolt through centre so you can tighten without twisting the hose. Just tell âem to copy your old one bar the metric end. Ensure they give you the right bolt for the right Banjo. Some are grooved bolt and some are grooved Banjo for hydraulic fluid flow. You MUST put in the two new copper washers to seal the bolt.
7) Putting everything back together! IMPORTANT. Depending on the pads you use, you will need to take a bit off the internal radius on the central hub side of the pad. A bench grinder will do this nicely. You need only do the outer pad, but make sure you put it on the outside of the caliper! As they wear in they may begin to touch on the hub of the disk causing a squeak or uneven pad wear.
The most critical stage. Once you have re-assembled everything and bled the brakes, turn the wheel by hand check your work. Then TEST, TEST, TEST, before you even go onto the road. Then when youâre on the road, TEST again in a safe spot. Not whilst you coming down a steep hill or driveway. Then check your handy work again back home.
Cheers