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H233b Rear Drum Brake To Disc Brake Swap


88pathoffroad
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After all this time and much discussion regarding thrust blocks inside drum brake centersections, I thought a swap would involve pulling the diff and removing the block, but apparently the axles are both the same exact length and all that is required are the parts from a donor axle. NICE!

 

Nissannut from nissan4wheelers has done the swap and shows you how...on a HB pickup. It'd be way easier on a Pathy, you'd just need the disc e-brake cables instead of modifying the HB e-brake setup. Include a new disc brake master cylinder with the swap and you're done with minimal fuss.

 

http://nissannut.com/projects/H233b_disc_brakes/

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I did a rear disc swap back in 1999. The donor was a 1995 LE i found in a JY one day. You can either swap the entire rear axle assembly or unbolt each

side of the axle with the drum brakes, bolt in the disk brakes and replace the brake line that are connected on the tee fitting.

I kept everything else ( ABS, ECU, master cylinder) the same. You can also keep your original diff in the process.

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I kept everything else ( ABS, ECU, master cylinder) the same. You can also keep your original diff in the process.

 

 

But do you have full braking in the rear using the original MC?

 

On disk brake systems there is a back pressure built into the system via the MC. I do not recall the exact PSI now, but some pressure is kept in the lines to make sure that the calipers keep the pads at the disk so when you press the brake pedal they respond right away.

 

Without that pressure the pistons are allowed to return to a fully open position and as a result you will not get any braking until the calipers pistons have moved from fully open, to the point the pads make contact with the disks. In some cases you may actually have to pump the brakes in order to get full or in extreme cases, any braking at all.

 

Now I am not trying to say that your setup is not working, just cautioning you that you are likely not getting "full" braking in the rear like you should. ;)

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Good to know, thanks everybody.

 

So, parts list:

 

axleshafts with disc brakes equipped

hard brake lines from center of rear axle to brakes

disc MC if so desired

e-brake cables for discs

 

That's about it.

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bach(black92se) did disk swap and keeped the drum MC. I belive he later switch to the disk MC and noticed no difference.

 

Ditto here. I could not notice any difference in braking.

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But do you have full braking in the rear using the original MC?

 

On disk brake systems there is a back pressure built into the system via the MC. I do not recall the exact PSI now, but some pressure is kept in the lines to make sure that the calipers keep the pads at the disk so when you press the brake pedal they respond right away.

 

Without that pressure the pistons are allowed to return to a fully open position and as a result you will not get any braking until the calipers pistons have moved from fully open, to the point the pads make contact with the disks. In some cases you may actually have to pump the brakes in order to get full or in extreme cases, any braking at all.

 

Now I am not trying to say that your setup is not working, just cautioning you that you are likely not getting "full" braking in the rear like you should. ;)

 

 

I check my 1991 service manual and there's only one MC available for both disk and drum setups either with rear ABS or not.

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I check my 1991 service manual and there's only one MC available for both disk and drum setups either with rear ABS or not.

 

 

Not sure why, but parts stores list three of them.

1: 2 wheel Disks

2: 4 wheels disks

3: ABS

 

Perhaps the ABS controls the back presurre in rear disk and antilock setup. :shrug:

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Why meaning, you said that your "1991 service manual" listed only one, but the parts store I checked listed three of them each with seperate part numbers and prices.

 

One thing of note is that not one of the manufactures listed had all three, instead it was two of the three, but not all the same. It could just be that the store does not carry the full line from each manufactures.. that happens a lot.

 

When it comes to brakes I prefer to play it safe, the parts numbers are all different so I am not willing to "assume" that the parts are all the same. They may appear to be from the outside, but that says nothing of thier design on the inside.

 

I am considering the disk swap (not anytime soon though) so a call the dealer to ask if the MC's do fully interchange may be in order here. If they say no then IMO it's not worth pushing ones luck... brakes are simply to important to risk them not working 100% :shrug:

 

Just my opinion, carry on :aok:

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I rechecked again and I was a bit hasty in writing last time. This is what I got:

Pathfinders and 4WD trucks have a proportional valve in their MC and don't use a load sensing valve

Some 2WD and 4WD pickups use a load sensing valve (LSV) and use a different master cylinder. There are only two MCs

depending whether an LSV is there or not.

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Good to know, thanks for the info.

 

Another thing to think about is using a 83-97(?) Chevy truck MC and modifying your stock brake lines. The Chevy MC has a higher capacity and increased line pressure, which equates to better braking (as long as your rubber brake lines are in good shape). To do that swap, all you have to do is enlarge the stud holes on the MC so it physically bolts on, then cut the metric ends off the brake lines, get a single tee fitting, some extra brake line and some SAE threaded line fittings, then put the fittings on and re-flare the lines, then reconnect to the Chevy MC. The Chevy MC has two outputs instead of three like the Nissan MC has, hence the tee fitting. Several people on Nissanoffroad did this and report good results. I know I've been thinking about it, 'cos my brakes have sucked BAD since day one.

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Hey all,

Just wondering , when you guys did the drum to disc swap in the rear did you swap the whole diff as I brought a wrecked 91 terrano and want to put the rear diff in my 88 model, also do terrano`s run different diff ratios and can you tell by the compliance plate. Not much of a problem as i also have the front diff as well but just means more work...

 

Thanks Guys.... :beer:

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Hey all,

Just wondering , when you guys did the drum to disc swap in the rear did you swap the whole diff as I brought a wrecked 91 terrano and want to put the rear diff in my 88 model, also do terrano`s run different diff ratios and can you tell by the compliance plate. Not much of a problem as i also have the front diff as well but just means more work...

 

Thanks Guys.... :beer:

 

Not the whole diff for me, I just pulled the drive shaft assembly from each side of the donor Pathfinder and bolt it onto mine and change two brake lines.

My original diff was the open type (3.25 if I guessed right). I now have an LSD with 3.6 gears. As far as I'm aware, all rear disk Pathfinders come with LSD & 3.6 gear.

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  • 2 weeks later...

Here's some more info on the bigger MC swap from Hillclimber/Homercules on N4W.

 

Posted June 08, 2007 02:37 PM

Alright heres the deal, i know there are a ton of Questions but I wont be able to answer them all, one of my friends has recently done this on his pathy and has improved the process, but its a bit more $$.

 

Homercules: I just finished my new brake setup. Originally I bought a chevy blazer mc but it is a tank so while I was cruising through the wreckers I found a Dodge full size van with an alloy MC. The bore size measured 1-1/8 so I installed it with a wilwood porportioning valve and stripped out all the ABS crap and it's working good. Nice feel to the pedal but I'm not sure on the porportioning yet. It's set to off (no porportioning) and it seems to brake ok. Much better than before.

 

The install was far easier for this Master Cylinder than the Chevy. On the Chevy you need to shorten the push rod and/or cut it down but the Dodge only needed a slight adjustment. The mounting holes need to be drilled slightly larger is all. And is a 1/4 the weight"

 

THis is more or less what I did.

"The chevy MC can be used out of the late 70's 1/2 or 3/4 tonne trucks, 78 1/2 ton blazer is what I told the parts store. The 1/2 ton has a 15/16" bore verse the 7/8" bore of the nissan, so its just a little more fluid, with the added bonus of only 25 bucks new for one. I didnt use the porportioning valve, however you should be using it, especialy if you have the rear discs, as my rear locks up at the same time as the front. I would mount it between the rubber line on the rear axle and the body. As for more push, yeah it has more peddle feel, and doesnt bottom out half as bad, I can lock the front brakes again, and the rear really easy. The only advice I have learned is to make sure that the rebuilt unit actully works before you install it, do the proper overnight bench bleed.

I had a trial and error setup, I tried and I errored. The spacer is not required if you adjust the push rod, like kev mentions, but unfortunetly the push rod end only goes in 1/4" or so. I ended up grinding most of the little end piece off and putting it back on the rod, you will also need to grind some metal off the tabs of the chev MC so the studs will have some threads left, and drill the holes out bigger so they match up with them, or slot the holes out. I had the spacers because my first MC didnt have the push rod end ground off. The sitting position for the MC is for NO preload on the ram, that is the push rod Cant, or shouldnt push the ram with out you hitting the brakes, it should just barly touch so you dont have delay.

 

As for the bleeding, clamp it to a vice, put the little plastic plugs in the MC, fill with clean fluid. Push slowly on the ram with the end of a tool, (Sans lid) lid off, slowly, it will spurt out fluid at you in the eye. Let the bubbles come out, repeat for about 20-30 times, let it sit for a while and repeat a few more times untill bubbles stop. Leave it over night, then do it again, if it wont stop bubbling then its not sealed proper and may be bad, then decide if you want to void the warrenty and drill into it.

I have some pics on my site, feel free to ask anything eles. heres the link http://www.cardomain.com/ride/572697/3

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  • 5 years later...

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