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240z SCCA vintage race car, restoration

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Hi all! So I need some help with the driveshaft. When I received the car, it has an R200 installed and this driveshaft (the one I am using). I swapped out the R200 for a Subaru STI R180. I also swapped the bottom-mount for the RT top mount. Unfortunately, the driveshaft no longer fits. It has bottomed-out in the trans side and appears to still be a few millimeters too long for the diff side. I measure 29.75”, or 755mm from the end of the yoke to the diff mounting flange. 

Is there a shorter driveshaft that was made? I had the impression all the S30 driveshafts were the same length. Could there be an issue with installing the RT mount on a series one (which this is)? 

I can have a shop shorten the driveshaft, but I’m concerned there is a bigger issue such as my diff sitting too far forward 




Edited by AydinZ71
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Hi all. Looks like the community may not know what could be causing the length issue on the driveshaft. 

I would like to try this another way. Are the axle shafts intended to be on the same XY plane of the wheel hub, and just angled down to accommodate suspension travel? If so, I can put a laser level on the output of the diff to make sure it is not too forward/aft. Then I will have confidence that my long driveshaft issue is not also causing an axle shaft misalignment. Then I will just shorten the driveshaft and call it a day! 

also seen some chatter on hybrid about rear diff alignment issues with a series one (which this is) but I could not seem to find a solution documented or my specific issue. 


what are your thoughts? 

Edited by AydinZ71
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Aydin, the series 1 cars had a shorter driveshaft IIRC, due to different diff mounting location.  They also used a "straight" (i.e., non-curved) transverse link behind the diff.  What did you do vis-a-vis the mustache bar when you swapped the R200 for the R180?  I suspect that may be the root cause of your issue.  (The RT-style forward mount should not be an issue either way.)


Yes, the half-shafts are essentially perpendicular to the longitudinal axis formed by the driveshaft and differential (on cars later than Series 1).


Hope this helps you get it sorted.

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Thank you John! @jhm, Clark! @clarkspeed


here are some shots of my mustache bar installed. Had an R200 w/ accompanying mustache bar when I bought it. I sourced a 240z mustache bar locally to accommodate the R180. I recall it was a bit difficult to get the RT mount into place. Took some rubber mallet hammering, and the bolt/nut interface took some static force to get into position. 

Was there a significant issue with the series one diff location (as I appear to have it in now)? I would imagine fixing the alignment issue will require me to slot or re-drill the single bolt drop-mount in the RT brace. Totally doable if necessary, but like everyone else in history, I hate dropping a diff haha. 

I still need to go get a laser level with a mag mount. Based on what you are saying John, I now have it back in the original series one position which requires a shorter driveshaft than the PO had installed with their R200 and associated parts. 

Found a local shop that will make me an aluminum driveshaft ($600)  which I can seamlessly shorten to correct this issue, while lightening simultaneously. So it sounds like now I just need to decide if I should shorten the driveshaft or move the diff back a 1/4” or so. 

If you have a laser level you enjoy using for these applications, let me know and il source it on Amazon! Very clearly, drivetrain and suspension angles are not my strong suit, haha.  Thank you! 




Edited by AydinZ71
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Hi all!


Thank you for your help @jonbill @clarkspeed @jhm

So I am a little confused on the mustache bar. This is an R180 in a series one 240Z. Looking at the stock photo (attached), it shows the mustache bar in the same orientation as I have it now. Do you guys have the mustache bar mounted behind the LCA vertical supports for an R200, or also for an R180? hmmm... any idea why the OEM photo has it turned the other way?


I bought a laser level, but it really was not designed for what I am trying to check. The back of it was curved, and seemed limited to something used for hanging something on a wall LOL.  I need something that would sit flush against the diff axle output and check where the cross-hatch ends up on the hub/stub axle. Have not found a tool that can do this yet. 


I Pulled the diff, and thank you John for the nudge. The Subaru STI R180 and the Datsun truck R180 w/ the 4.11 gearset are at the diff shop. They are going to swap the STI carrier into the 4.11 for me. I have CV axles adapted to the STI carrier splines so should work OK. 


I read a few posts about folks having trouble with the RT mount and a series one. One post mentioned turning the mount 180 degrees, which puts the fuel line notch on the wrong side, but I suppose I can accommodate. I am attaching some photo's of how I have it mounted today. Maybe someone sees something wrong here.


In conclusion, I guess I need to definitively conclude which orientation of the mustache bar is correct for a series one with an R180. I can do whatever I need to for the RT mount to make it work. John mentioned the mustache bar really should be setting the for-aft orientation of the diff which makes perfect sense to me. 


Thanks again for all your help folks!




Edited by AydinZ71
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Got the STI carrier into the 4.11 open diff. Time to remount the diff. Curious question now is, was there a difference between the series one mustache bar and the 71-73’? Will get it mounted and see how far the diff alignment is.


front suspension also complete. Need to install sway bar and front wheel bearings. IMG_1564.jpeg.0a8e4bb86dbabbf4eeeb8c33879218bb.jpeg


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@jhm yes sir, fabbed myself. There is a face mounted bearing that goes on those drop mounts. They have two ribs on the back side you cant see, for stiffness. I would say the centerline of the bar drops about 3". I mocked it based on how low I needed it to clear the oil pump, from my street Z. I think there are some older posts of mine that should have it in a lot more detail. I will have it mounted soon and will give you some more pics.


@calZ Thanks. Yep, I believe I solved my problem. 

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  • 2 weeks later...

The plan was to weight the car before changing the brakes. Hit a roadblock. One of the two rear brake drums appears to be clogged/seized. Can’t get fluid to come out of the bleed port. The other cylinder is not much better, but it’s got fluid coming out at least. It’s a challenge to bleed brand new brake lines with dual masters, so I have to bleed the front and rear simultaneously. 

Seems silly to replace the drum cylinder now just to remove them again after j a few months, so it looks like I’ll have to do the rear disk conversion now. 

@clarkspeed dusting off your really helpful e-mails on the rear brake design and brake setup. I’ll make an initial plan and look forward to your feedback.


primary concern now is to ensure I don’t go TOO big in the rear so my brake bias is not too lopsided. 







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Bleed F and R simultaneously? Don't understand. Usually the balance bar self adjusts and allows you to bleed each wheel as normal. Feels wierd, but works fine. I don't do anything different with dual master as I would with a single. 


Let me know what you are thinking. Usually a non issue getting rear too strong. I tend to experiment with rear pad materials if things are too outa-whack. I have run street pads in rear before. 

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@clarkspeed thanks Clark. Because the brake lines and masters were all newly installed, I struggled getting enough “throw” without having the front bleed with the rear. I bled the front first so they had little travel. The front would lock up quick and the balance bar would give me another 3/8” throw on the rear as it pivots. I bet it would be fine if my rear drum cylinder was not clogged, but I seemed to be just compressing air in the rear line. 

going to get going on the rear drum-rotor conversion w/ the dynalite calipers. Thanks again for all the files you sent a few months ago! Il try to pick a reasonable rotor diameter so balancing with the fronts aren’t a challenge, and I’ll use your calc. 

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What worked for me with an entirely new brake system was pushing fluid backwards. Open the bleeder, use a tube feeding syringe to force fluid to the master. I tried everything; pump/hold/open bleeder, gravity bleed, repeated pumps with hose submerged, vacuum bleed, couldn't get a pedal until I reverse bled.

Good luck. It was frustrating as hell for me.


Edited by JMortensen
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