For those w/ rear disc conversions

[xShodaimex]

I have a 260z Late model I believe [guessing from the huge bumpers]. My drum brakes hardly work and the shoes are about gone so I've decided that instead of replacing them I will convert them to disc brakes. I have done some research and read for about 3 hours now. So far I have read about using maxima brackets and I do not want to go that direction, I've read some people have trouble with the 280zx calipers .

 

I also read about using the brackets from Modern Motorsports which uses the 88-94 240sx rear calipers and 83-85 300zx rotors.

 

I wanna know which packages you guys have or which rear conversions you guys have. Which ones are easy to do and give good results. Thanks guys!

[19762802+2]

I haven't installed mine yet but I plan on going the Modern Motorsports way. I bought Calipers and Rotors and Studs at the junkyard for $70 and saved about $1100 then if I bought everything new and fancy.

[xShodaimex]

I haven't installed mine yet but I plan on going the Modern Motorsports way. I bought Calipers and Rotors and Studs at the junkyard for $70 and saved about $1100 then if I bought everything new and fancy.

 

Yeah those complete kits can be really pricey. So for 70 bucks you got yourself a pair of 240sx Calipers and a pair of z31 rotors. Wow thats a save. I get paid tommorrow and will most likely go to a local Junkyard to get myself those calipers/rotors too. Let me know how your installation goes!

[xShodaimex]

Sorry guys I just realized that this thread should be in the brakes section.

[Zmanco]

I've had the Modern Motorsports brackets and 240sx calipers on my 73 for a few years now and have been very happy with them. There is one big "but": I also did the toyota 4x4 vented caliper swap and even with the proportioning valve all the way open, the fronts lock first. This means that the rears are not being used to their potential. I've since swapped to a rear pad with a different coefficient of friction and that made it better. If you go this route, be prepared to experiment with different pad materials to get the most out of the upgrade.

 

You didn't say what you're running for front brakes. If they're stock, this might not be an issue.

[xShodaimex]

I've had the Modern Motorsports brackets and 240sx calipers on my 73 for a few years now and have been very happy with them. There is one big "but": I also did the toyota 4x4 vented caliper swap and even with the proportioning valve all the way open, the fronts lock first. This means that the rears are not being used to their potential. I've since swapped to a rear pad with a different coefficient of friction and that made it better. If you go this route, be prepared to experiment with different pad materials to get the most out of the upgrade.

 

You didn't say what you're running for front brakes. If they're stock, this might not be an issue.

 

For the fronts I'm keeping them stock for now. I'm just worried about the back since my drum shoes are all worn. So how many different sets of pads did you go through in order to make it suit you? Oh I was also wondering if you bought the rotors with the package that they offer or did you buy them separate? I'm getting my check today so I'm going hunting!

[Zmanco]

So how many different sets of pads did you go through in order to make it suit you? Oh I was also wondering if you bought the rotors with the package that they offer or did you buy them separate?

I've played around with a few, but wouldn't recommend any for the track yet. My next set (when these are worn) will likely be Porterfield R4S in the front and R4 in the rear. The R4s probably won't do much on the street when cold, but I only drive it for fun when it's nice weather, so am not worried.

 

I did mine before kits were popular. I sourced the brackets and SS lines from Ross, but found everything else locally for a lot less, especially when factoring in shipping heavy calipers and rotors from Canada.

[Six_Shooter]

I had the 280zx rear disc conversion on my car.

 

BTW, the conversion uses the 280zx caliper caliper hanger and rotor, not the 300zx rotor (at least not the turbo rotor), and the Maxima calper brackets.

 

The 280zx set-up worked well, and if I was keeping the 4 lug set-up I'd keep the rear brakes as they were. I would make a slight modification to the e-brake system, as I have done now, and that is to move an attachment point on the intermediate parking brake lever system.

 

My "new" rear brake system will keep the 280zx rear calipers, Maxima caliper brackets (slightly modified), and use 300zx rear disc and caliper hangers. I am doing it this way for the 5 bolt conversion. I didn't want to drill the rotor for the 5 bolt pattern, even though that would have been a MUCH easier way to do it. LOL The 300zx rotor is larger in diameter, than the 280zx rotor.

 

FWIW, I bought my calipers used, and haven't had a problem with them. I thought I did initially have a problem with the parking brake system, but that seemed to be an adjustment issue, not a functioning issue. The only other issue I have had was the parking brake cable siezing on one side, but that was an original 240Z cable, so it wouldn't be fair to say it was due to the disc swap.

Edited June 15, 2010 by Six_Shooter

[xShodaimex]

I had the 280zx rear disc conversion on my car.

 

BTW, the conversion uses the 280zx caliper caliper hanger and rotor, not the 300zx rotor (at least not the turbo rotor), and the Maxima calper brackets.

 

The 280zx set-up worked well, and if I was keeping the 4 lug set-up I'd keep the rear brakes as they were. I would make a slight modification to the e-brake system, as I have done now, and that is to move an attachment point on the intermediate parking brake lever system.

 

My "new" rear brake system will keep the 280zx rear calipers, Maxima caliper brackets (slightly modified), and use 300zx rear disc and caliper hangers. I am doing it this way for the 5 bolt conversion. I didn't want to drill the rotor for the 5 bolt pattern, even though that would have been a MUCH easier way to do it. LOL The 300zx rotor is larger in diameter, than the 280zx rotor.

 

FWIW, I bought my calipers used, and haven't had a problem with them. I thought I did initially have a problem with the parking brake system, but that seemed to be an adjustment issue, not a functioning issue. The only other issue I have had was the parking brake cable siezing on one side, but that was an original 240Z cable, so it wouldn't be fair to say it was due to the disc swap.

 

 

So you went with the Maxima/280zx combo. Hmmm. Interesting.. I appreciate you guys giving me insight on this. Thank you all!. Now I gotta figure out which one I want..

[Six_Shooter]

Now I gotta figure out which one I want..

 

That's usually the hardest thing to do. LOL

 

I usually go with what's avilable to me easily or cheaply. LOL

[xShodaimex]

That's usually the hardest thing to do. LOL

 

I usually go with what's avilable to me easily or cheaply. LOL

 

I have decided to go with the Modern Motorsports brackets! I'd just got done placing my order!

[Zmanco]

I went that route because the rotors are a little larger diameter which should in theory (all else being equal which it never is) allow more braking torque. You can always reduce it in the rear via the proportioning valve, but you can't increase it.

 

You didn't say what the rest of your plans are, but given you're going with the stock fronts for at least a while, make sure you install a proportioning valve.

[ktm]

I went that route because the rotors are a little larger diameter which should in theory (all else being equal which it never is) allow more braking torque. You can always reduce it in the rear via the proportioning valve, but you can't increase it.

 

You didn't say what the rest of your plans are, but given you're going with the stock fronts for at least a while, make sure you install a proportioning valve.

 

Correct. I am running the 240sx rear brakes as well but I also have the vented 4x4 brakes up front. You really need to run a proportioning valve when using the 240sx rear disc setup.

 

Zmanco, I agonized forever over this setup as I was worried about too much front bias, too much rear bias, etc. In the end I went with the Porterfield R4S in the front and the discs ross sells with his setup (I can not remember their name at this time). My rears locked up first with the valve all the way open and I was able to dial in the bias.

[xShodaimex]

I went that route because the rotors are a little larger diameter which should in theory (all else being equal which it never is) allow more braking torque. You can always reduce it in the rear via the proportioning valve, but you can't increase it.

 

You didn't say what the rest of your plans are, but given you're going with the stock fronts for at least a while, make sure you install a proportioning valve.

 

Yeah I was planning on keeping the front stock and use the 240sx calipers w/ the 4lug 300zx rotors. About the proportioning valve, I have read about it but I'm not very familiar with brakes so I wouldn't know where it goes and what purpose it serves.

 

I was planning on doing a turbo swap to my car so I thought having disc brakes in the rear would help with the braking power. I don't plan on using it on the track or anything like that, just for my personal satisfaction.

Edited June 16, 2010 by xShodaimex

[Zmanco]

Zmanco, I agonized forever over this setup as I was worried about too much front bias, too much rear bias, etc. In the end I went with the Porterfield R4S in the front and the discs ross sells with his setup (I can not remember their name at this time). My rears locked up first with the valve all the way open and I was able to dial in the bias.

Bo, are you using the pads that Ross supplied for the rears? I believe they are some type of carbon-kevlar material, but don't know what brand. Good to hear that you had enough rear brake so you could set the proper balance with the prop valve.

 

Yeah I was planning on keeping the front stock and use the 240sx calipers w/ the 4lug 300zx rotors. About the proportioning valve, I have read about it but I'm not very familiar with brakes so I wouldn't know where it goes and what purpose it serves.

 

I was planning on doing a turbo swap to my car so I thought having disc brakes in the rear would help with the braking power. I don't plan on using it on the track or anything like that, just for my personal satisfaction

For purely street use, especially if you're leaving the rest of the system stock, there's really no functional benefit to swapping the rears to discs. But they do look good

 

I would expect the drums to be more mechanically efficient that discs so if you just replace them with discs and leave the stock prop valve in, I suspect you'll still lock the fronts first. But I'll also guess that you'll be getting LESS rear brake contribution than with stock drums, so the net is that you'll likely INCREASE stopping distances. You should find a safe place to experiment with hard stops to find out how things have changed.

 

[soapbox] You really should study up on how brake systems work, especially proportioning valves. If you don't plan out the system and optimize it, you will likely either 1) INCREASE the stopping distances, or 2) get TOO MUCH rear brake and cause the car to SWAP ENDS in a panic stop. Either way you have made your car less safe. There is a ton of good discussions on these topics here as well as on a few manufacturer sites (Stoptech IIRC has a good discussion on how prop valves work). Just bolting parts on without a plan or taking the time to optimize them rarely improves things. Engineering is almost always harder than that. [/soapbox]

[Six_Shooter]

On one of my cars (not an S30), I swapped to rear discs, without changing ANYTHING else, and the car stopped quite a bit better. I then swapped to a larger front brake, but didn't see much improvement in braking.

 

So if there is no benefit to swapping to rear disc, why do so many cars now come factory equipped with rear disc brakes?

 

While I agree that some study should be done to ensure that everything is working together, but I have yet to see or talk to anyone that has experianced these "unsafe conditions" or "swap the car end for end", or increase braking distances from a brake swap to something with greater braking potential.

Edited June 16, 2010 by Six_Shooter

[Zmanco]

On one of my cars (not an S30), I swapped to rear discs, without changing ANYTHING else, and the car stopped quite a bit better. I then swapped to a larger front brake, but didn't see much improvement in braking.

Now and then a skydiver's parachute fails to open and they still live. Does that mean that skydivers don't need to use parachutes? A single case doesn't prove a point.

 

So if there is no benefit to swapping to rear disc, why do so many cars now come factory equipped with rear disc brakes?

Two answers:

1) I never said that discs weren't better than drums when designing a system from scratch as is the case with modern cars. But that's not what we have here. In this case we have an existing car that was designed and optimized for drums in the rear.

2) With the advent of traction control and VDC the brakes can be used for purposes besides stopping the car and hence can find themselves asked to dissipate even more heat. Discs do that better than drums.

 

While I agree that some study should be done to ensure that everything is working together, but I have yet to see or talk to anyone that has experianced these "unsafe conditions" or "swap the car end for end", or increase braking distances from a brake swap to something with greater braking potential.

The stock brake system when in good condition has enough braking force to lock all 4 wheels. It also has enough heat dissipation capability to stop the car from freeway speeds without fade at least once. So the benefits of upgrading are to be able to make repeated stops without fade and the corresponding longer stopping distances.

 

Changing the brake equipment will almost certainly affect how much braking force is generated for a given amount of brake pedal pressure. Given that the stock system is well balanced between front and back (I'm sure the Nissan engineers spent some considerable time to obtain this), changing the brake equipment at only one end is bound to upset that balance.

 

Adding bigger brakes in front will likely cause the fronts to lock even sooner than the rears, thus lengthening the stopping distance. This is not an improvement.

 

Changing the rears from drum to disc will either result in more or less braking force for a given brake pedal force. If it's more, then it's possible the rears will lock first. A spin is likely if this happens. If it's less, then the rears are actually doing less work than the drums were and the stopping distance will be longer. Again, this is not an improvement.

 

I do think that many people who upgrade start with stock systems in poor condition and hence attribute the improvement to the upgrade when in fact they would have achieved the same thing, maybe even better, by rebuilding the stock system and changing to higher temp pads and fluid.

 

FWIW, when I first bought my Z 7 years ago I remember reading a post by either JohnC or Jon M saying essentially the same thing I am here. I went ahead anyway and did the toyota 4x4 caliper upgrade keeping the solid discs. On the street things were about the same (I never measured stopping distance so don't know if I made it worse or not), and on the track they faded a little less, mostly due to the extra thermal mass of the larger calipers I suspect. It was a lot easier to lock the fronts though so my stopping distances grew longer. I've since upgraded to vented rotors in front and discs in the rear and an adjustable proportioning valve and the improvement on the track is huge. But on the street, I doubt I stop any shorter. Given the OP said he was only interested in street driving, I think he could have spent the money and time on some other aspect of the car for more benefit.

 

One last thing: we all have our cars because in the end, they are supposed to make us happy. If changing to discs in the rear helps, then go for it - just do it safely.

[xShodaimex]

wow I didnt realize this.. I should've studied more on the functions. I really need to read more about proportioning valve and stuff. Anyways, I went to three junk yards today and to my amazement, I only found ONE 240sx. And it was missing the rear rotors..

[Six_Shooter]

Now and then a skydiver's parachute fails to open and they still live. Does that mean that skydivers don't need to use parachutes? A single case doesn't prove a point.

 

Funny you say that, my Grandmother went skydiving several years ago, her 'chute didn't deploy fully, landed in a corn field, then was in the hospital for a couple months with a compressed spine.

 

I mentioned one of my experiances, though I have had several experiances with swapping to rear disc and in each case braking was improved. My daily driver has had the brakes upgraded all the way around and the braking was much better because of it. Braking was improved the most with just the rear disc, the fronts didn't have as dramatic of an improvement.

 

 

Two answers:

1) I never said that discs weren't better than drums when designing a system from scratch as is the case with modern cars. But that's not what we have here. In this case we have an existing car that was designed and optimized for drums in the rear.

2) With the advent of traction control and VDC the brakes can be used for purposes besides stopping the car and hence can find themselves asked to dissipate even more heat. Discs do that better than drums.

 

I love guys like you that attribute all of these common changes to something else that could be on the car, when in most cases those items, such as traction control are not present, and yet most vehicles now come with these advances, such as rear disc, because they are simpler, shed water better than drum, and have better cooling capabilities than most drums would.

You also don't need to start from scratch to swap to rear disc, doing some reading on setting up brake bias, through use of rotor diameters and piston diameters might help shed some light on why some systems work better than others. I have several books that go into detail about these variables, leaving those adjustable proportioning valves out of the equasion. I'm not syaing they aren't needed, but in a properly planned system, that may only have a change to one axle, it likely won't be needed.

 

 

The stock brake system when in good condition has enough braking force to lock all 4 wheels. It also has enough heat dissipation capability to stop the car from freeway speeds without fade at least once. So the benefits of upgrading are to be able to make repeated stops without fade and the corresponding longer stopping distances.

 

So what if you can lock the brakes with the stock system? That is NOT an indication of braking abilities. A system that has greater braking potential, will give you better ability to modulate the brakes and keep the wheels spinning, while applying a slowing (braking) force. With the wheels locked, you have no diractional control and can slide farther than if the wheels were still able to spin, tire design has a rather large effect on this too.

 

Changing the brake equipment will almost certainly affect how much braking force is generated for a given amount of brake pedal pressure. Given that the stock system is well balanced between front and back (I'm sure the Nissan engineers spent some considerable time to obtain this), changing the brake equipment at only one end is bound to upset that balance.

 

Adding bigger brakes in front will likely cause the fronts to lock even sooner than the rears, thus lengthening the stopping distance. This is not an improvement.

 

Changing the rears from drum to disc will either result in more or less braking force for a given brake pedal force. If it's more, then it's possible the rears will lock first. A spin is likely if this happens. If it's less, then the rears are actually doing less work than the drums were and the stopping distance will be longer. Again, this is not an improvement.

 

Likely, could, maybe, might, all words that show speculation, without going through the steps to finding out what does and doesn't effect this. I can also say: "Swapping brakes might increase the braking ability of the car." or "Increasing the braking potential will likely improve braking performance." I guess I look at the cup as half full, and find ways to make something work better than it was intended to, instead of trying to discourage people from finding ways of improving of what they use.

 

I do think that many people who upgrade start with stock systems in poor condition and hence attribute the improvement to the upgrade when in fact they would have achieved the same thing, maybe even better, by rebuilding the stock system and changing to higher temp pads and fluid.

 

I agree, happens with more than just brakes, or even with more than just cars, but how many people are really going to remove a completly fresh built braking/starting/turbo/shower/stove/washing/etc. system, just to replace it with something else to see just how effective it is? Most people can also relate the new system, they are using to when the old system was nnew, or even how the new system wears over time compared to the old system.

 

FWIW, when I first bought my Z 7 years ago I remember reading a post by either JohnC or Jon M saying essentially the same thing I am here. I went ahead anyway and did the toyota 4x4 caliper upgrade keeping the solid discs. On the street things were about the same (I never measured stopping distance so don't know if I made it worse or not), and on the track they faded a little less, mostly due to the extra thermal mass of the larger calipers I suspect. It was a lot easier to lock the fronts though so my stopping distances grew longer. I've since upgraded to vented rotors in front and discs in the rear and an adjustable proportioning valve and the improvement on the track is huge. But on the street, I doubt I stop any shorter. Given the OP said he was only interested in street driving, I think he could have spent the money and time on some other aspect of the car for more benefit.

 

I have had that same member try to tell me he knows more about my car than I do, based on one little fact of my car having a similar braking system to what he had. :facepalm: Funny, how I'm the one that drives it and knows how it performs, and what might or might not need improvement.

 

One last thing: we all have our cars because in the end, they are supposed to make us happy. If changing to discs in the rear helps, then go for it - just do it safely.

 

I agree.

Edited June 17, 2010 by Six_Shooter

[Nigel]

I just ordered the Silver Mine Motors rear setup...

 

http://www.silverminemotors.com/product.sc?productId=38&categoryId=12

 

11.8" vented rotors and 43mm caliper pistons from '05 to '10 Mustangs.

 

Can't wait to try them out!

 

Nigel

'73 240ZT