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Anyone know if RX7 calipers are the same as vr4/300zx ?


tux
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I posted before about the rx7 caliper bracket I found on a Japanese site.

Since revolution brakes doesn't seem to be interested in delivering a brake kit, I'm looking for an alternative.  

RX7 calipers are very expensive but I'm curious if they are the same as vr4 and 300zx calipers.  The mounting hole width appears to be the  the same based on my measurements of the vr4 calipers I have and comparing to this drawing for adapters https://www.aeu86.org/forum/Thread-HOWTO-Mazda-FC3S-4pot-Calipers?page=3

The Rx7 calipers are made by sumitomo.

 

Anyone know if they are compatible parts across all three makes?

 

 

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Rx7 calipers may be unique to that platform.  That would explain the price.  300zx and vr4 may have some slight difference to give it a different part #.  I don't know much about those applications so I can't be sure.

 

I will say that resource isn't perfect.  For example, my 91 toyota pickup and widebody SQs use the same front brake pads.  If you look up the pads for the toyota the compatibility tab says they only fit the toyota.  If you look up the SQ pad it says those pads fit dozens of vehicles including the toyota.  

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On 1/13/2023 at 12:13 AM, ucw458 said:

Rx7 calipers may be unique to that platform.  That would explain the price.  300zx and vr4 may have some slight difference to give it a different part #.  I don't know much about those applications so I can't be sure.

 

I will say that resource isn't perfect.  For example, my 91 toyota pickup and widebody SQs use the same front brake pads.  If you look up the pads for the toyota the compatibility tab says they only fit the toyota.  If you look up the SQ pad it says those pads fit dozens of vehicles including the toyota.  

All good, it was definitely worth a shot.

I know mounting holes are in same spot but the rest who knows

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  • 2 weeks later...

I'm not going to be able to find much, unfortunately.  RX7's aren't terribly common in these parts and too expensive to buy a caliper just to measure it.

I've started designing a caliper bracket for the 3kgt VR4/300zx calipers I currently have.  

Will just be 3d printing some test pieces and see if I can get those calipers in there and retain the stock wheels.  If not, I might look to some more common 4 pot Toyota/Sumitomo calipers.

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I'm gonna see about using Lexis ls430 sumitomo calipers. 

Radial mount, not terribly huge, 4 pot, dirt cheap, potentially be able to keep in same location as stock brakes and possibility of using standard rotors.

I came across a loaded pair for $95 on eBay and it seems to be the going rate.

Googling around it seems that some brackets are available for Porsche 944 and it's a somewhat common upgrade for them.

 

 

 

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Those LS430 calipers are cool. I didn't know they existed. The only radial-mount calipers I've ever seen were high-end aftermarket upgrades.

The biggest thing I'm worried about is the size of them. I'll be interested to see what you can come up with for a bracket and whether they will fit under the stock wheels.

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I was surprised when i was googling around Toyota 4 pot calipers to see them on a parts sheet.

Later googling lead to 944 forum where they were fitting them behind 15" rims.

 

I'm hopeful to see what happens.

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So.  I printed out a quick test bracket.  It looks like i can use a stock rotor. So that's a plus.

Not sure yet if it will fit behind the wheel, it looks like it may, I didn't try because the bracket made kept stock location and the caliper hits both the strut and tie rod.

 

I'm going to have to relocate the caliper to the front of the rotor and ditch the dust shield.

 

Likely it will be a slow moving project since i am not good at CAD and worse at making 3d models

Edited by tux
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https://photos.app.goo.gl/1wc79U1oNCPjLCaw5

Some pics and size comparisons between 3kgt vr4 calipers and the LS430.

The vr4 are way smaller.

Held both in place with zip ties and it's apparent a standard rim will not fit without a wheel spacer or finding a rotor that offsets further to the back or a combination of both. The face of the caliper has interference with the back of the rim spokes. It looks like i need about 25mm of clearance. 

 

I measure 23mm from the back face of the rotor to the back face of the OEM mounting lug. I'm going to need probably 6-8mm of that for a bracket

Could use 10-15mm wheel spacer and a rotor offset back another 15mm and longer wheel studs could help here. But it I'm not sure how the wheels would look sticking that far out

 

 

Edited by tux
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Please ignore the crappy coilovers, they will be removed before I drive this other car again.

AMWts8DtAXUWY8s0XRcNvwDmn296tedtWxh8cuvA

VR4 Caliper

 

AMWts8AedpZFNU7iYldvPnqMIvbP_Gn6hLODtQ1B

Needs a spacer but VR4 behind rim

 

AMWts8AFtEIrTSFaAT9mnSTKdJGqwHGmfI-yaXEK

LS430 Caliper

 

AMWts8CYBnCUi4uSWogXm08Ab4M41XxofQI9TT7f

LS430 Caliper behind wheel.

 

 

The LS430 caliper would be easier to adapter, since it is radial mount, but it might require a slightly larger rotor to accommodate  

Edited by tux
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Well, I tried 2 wheel spacers - 15mm and 10mm.  15mm has plenty of clearance but sticks out too far for my liking (unless I add more camber), and 10mm looks good, but doesn't clear (barely brushes both calipers.  I need something in between.

Rather than buying another set of spacers that I'm not going to use, I'm going to print out a 12mm spacer and see what that gives me in terms of clearance.

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On 2/6/2023 at 8:42 PM, obsolete said:

Interesting. How does the pad size for each of these calipers fit with the stock rotor? Is some of the pad hanging off the edge?

Yes.

 

There isn't much hanging off the vr4/300zx calipers, a little more hanging off on the ls430 calipers.  I found an old post about someone using crown Vic rotors. 

I may look into using the crown Vic rotors.  If they don't fit behind stock wheels w/ caliper from a test fit, i may see about getting them turned down to make them an in between rotor size.

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2 hours ago, ucw458 said:

How stiff are the springs on those coilovers?  I have a similar setup on mine but the springs seem too stiff.

Off topic, but I'm not sure.  I drove only 3 miles round trip to a shop for an alignment and they couldn't align with them.

 They are shoddily made and i was warned by another member about the dubious quality.  If you have the same coilovers and value your life, don't drive on them and swap for D2.   This is an unregistered car now.  I'm using it for random projects while my other starion is getting painted.

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20 hours ago, tux said:

Off topic, but I'm not sure.  I drove only 3 miles round trip to a shop for an alignment and they couldn't align with them.

 They are shoddily made and i was warned by another member about the dubious quality.  If you have the same coilovers and value your life, don't drive on them and swap for D2.   This is an unregistered car now.  I'm using it for random projects while my other starion is getting painted.

I have Eibach sleeve overs on my car.  They work fine except the springs seem too stiff.  If you push down on my fender the car doesn't move.  You seemed to not want to use those coilovers and that got me wondering if those springs are softer than mine.

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1 hour ago, ucw458 said:

I have Eibach sleeve overs on my car.  They work fine except the springs seem too stiff.  If you push down on my fender the car doesn't move.  You seemed to not want to use those coilovers and that got me wondering if those springs are softer than mine.

Sending pm

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  • 2 weeks later...

Ok so my cad skills stink.  I started off now attacking the vr4 calipers.

I made a cardboard bracket for now and I'm passing that off to my friend who is a draftsman to make a 2d model.  From there i can extrude it and make myself a 3d printed mock up.

Should the mockup work out, I'll get it made in aluminum.

If anyone else wants a set I'll find out how much it would be.

 

 

After i have the vr4 calipers done, I'll continue to work on a ls430 caliper bracket.

 

 

 

 

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  • 2 months later...

Slow progress here.

 

Everything is slightly off.  Either I'm really bad at CAD (I am) or bad at measuring things (possible too).

 

Every time I print out a bracket it's always slightly off, not from my model, but when I fit it on the car.

 

Still working on it though

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