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Anyone running an R180 for racing application?


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Hi there!

 

Still preparing the car for group EP, although @clarkspeed has showed me a few other orgs./classes that could work with my base chassis modifications. Appreciate the help!

The car (late series 1, titled 71') has been the drivetrain components swapped for an R200, and currently sits with a 3.545 open. A local friend of mine is parting out his 72', and im considering downsizing to an open R180. Searching forums, it looks to be a 20lb weight savings.

 

Anyone else running an R180 for a low-torque racing application? SCCA class EP, ITS, vintage are all using the L24 with SU carbs. each allows various levels of modification to the engine, but in every case I don't see torque exceeding 170ft-lbs. 

 

If you also agree an R180 may be a good choice for relatively low torque racing applications, any idea on swapping out the open center section with an LSD? I'm looking at subie STI 180's, but when you add the CV shaft conversion and adapters on, it gets quite expensive. 

 

-Aydin 

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Thanks for the wealth of knowledge! I reached out to Fritz and he showed me another source for the LSD. Il be placing an order for his shafts shortly. I think this will be the best value overall, give

@calZ LOL, fair point  I have been spending way too much time fabricating rust replacements, replacing roll bar mounts, and reinforcing the chassis. I think I'm getting carried away. I have been cutti

A couple of things based on 17 years and over 225+ track days with a 240 race car:   Stock diff mount welded with two steel bars (17 years and no issues) Engine HP ranged from 150 t

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I've been running an R180 for several years in various types of auto-x, time trials, HPDEs and lately 1/8 mi drag.  Very mild SBC build with a 200-4R, with A7s or full slicks.  My diff is a TORSEN LSD from an STi.  No CV axles.....just the machined adapter side axles with stock half-shafts.  Has been amazingly reliable (knock on wood).  I've even seen people use the LSD R160s with some good success on low power/light weight applications.

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21 minutes ago, jhm said:

I've been running an R180 for several years in various types of auto-x, time trials, HPDEs and lately 1/8 mi drag.  Very mild SBC build with a 200-4R, with A7s or full slicks.  My diff is a TORSEN LSD from an STi.  No CV axles.....just the machined adapter side axles with stock half-shafts.  Has been amazingly reliable (knock on wood).  I've even seen people use the LSD R160s with some good success on low power/light weight applications.

 

Hey thanks for responding! Looks like the stub adapters are about $500 from a few sources. Having no idea where to look, I see some STI R180's on ebay for $600-1000. Not the cheapest way to an LSD, but lighter so more appropriate for an NA L24. Il look into the R160's as well. I have read a bit about how CV's have less rotational inertia, and have less vibration at higher speeds. First hand experience, I do get quite a bit of vibration from the rear-end over ~100mph. I have had the press-fit U-joints fail in the past, but it seems people are just giving away stock 240z shafts these days. Is the only reason you have not gone CV's yet because of the extra cost?

 

appreciate your knowledge!

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I think at under 200 ft/lbs you're probably going to be OK. One of our members, zredbaron, has a 300bhp L31 (I want to say it was more than 250 ft/lbs) and he's been through 3 different types of CVs IIRC and destroyed 2 diffs, snapped a mustache bar, I might be forgetting one or two other mishaps.

EDIT--If you do go with CVs, especially on a race car, safety wire them. They seem to have a way of loosening the bolts. 

Edited by JMortensen
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I think John Williams has the best price for adapter side axles...$400/pair last time I saw, on FB IIRC.  And yes, cost is why  I've stayed away from cv axles to date.  If you decide you really want to go with CVs, check out the slick pieces that Fritz is making at Datsunrestomods.com.  He produces axles that swap out 1-for-1 with stock half-shafts, and he also produces a style that's a direct bolt-in on a Subie LSD.  Keep in mind that CV axles can get in the way of other components, like sway bars, depending on which style axle you go with.

 

Regarding high-speed vibrations...try flipping the driveshaft and half-shafts 180 degrees, one unit at a time, to see if that helps.

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1 hour ago, jhm said:

I think John Williams has the best price for adapter side axles...$400/pair last time I saw, on FB IIRC.  And yes, cost is why  I've stayed away from cv axles to date.  If you decide you really want to go with CVs, check out the slick pieces that Fritz is making at Datsunrestomods.com.  He produces axles that swap out 1-for-1 with stock half-shafts, and he also produces a style that's a direct bolt-in on a Subie LSD.  Keep in mind that CV axles can get in the way of other components, like sway bars, depending on which style axle you go with.

 

Regarding high-speed vibrations...try flipping the driveshaft and half-shafts 180 degrees, one unit at a time, to see if that helps.


I think I’m sold on the datsunrestomod CV’s! Only $500 more than the adapters from John. Thanks for letting me know about these! 
 

now to source the STI r180... Il look on FB marketplace as well. 
 

when you say flip, you mean relative to the companion mounting flange right? The other side of the shaft being the spline end of course, so no use flipping there. 

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3 hours ago, JMortensen said:

I think at under 200 ft/lbs you're probably going to be OK. One of our members, zredbaron, has a 300bhp L31 (I want to say it was more than 250 ft/lbs) and he's been through 3 different types of CVs IIRC and destroyed 2 diffs, snapped a mustache bar, I might be forgetting one or two other mishaps.

EDIT--If you do go with CVs, especially on a race car, safety wire them. They seem to have a way of loosening the bolts. 


May yes! I recall something in the rule book about drivetrain components requiring “locking-type” fasteners (paraphrasing). I have had driveshaft bolts loosen on me, and ruin those pesky non-replaceable u-joints, so I have started a short torque wrench/ratchet. It’s hard to Get them tight enough on a 6” Long 12mm wrench alone. Not to mention the bolt/nut assembly can spin even with a lock washer sometimes. 
 

would love to hear his story on breaking a mustache bar! ... and here I was contemplating a lighter replacement using a rectangular steel tube with ribs. Not worth the effort at the moment. 

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WRT sourcing an LSD R180....there was a gentlemen on several of the Datsun FB pages who seemed to always have a stock of these available for sale.  Haven't seen his posts in a while, but that's a good place to start.  Also check out the Subaru forum pages...another good source.  Here are a couple links to pages with some good tech data on the R180 internals:

https://forums.nasioc.com/forums/showthread.php?t=2597453

https://forums.nasioc.com/forums/showthread.php?t=1969700

 

Yes, flip the flanges of each component 180 degrees relative to each other; but it's important to do this one component at a time, in order to isolate where the vibrations are originating from.  No guarantees that this will work for your issue, but it's solved the issue a couple of times for me in the past.

 

The owner of Datsunrestomods is on here, username @Dadzsun.  He's got a thread going in the Vendor's section.  Someday when I'm feeling rich, I'll probably spring for a pair of his axles.  :-)  I really like their non-reliance on adapter plates and dozens of allen bolts that Jon M mentioned. 

 

 

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Alright! order placed for the CV shafts with Fritz, and it seems I got one of two remaining February units. He helped me with some sources for the diff. Just purchased a 2017 3.545 Torsen model with 35k miles for $550 shipped to my home. I'm satisfied. 

 

Now I have upgraded a 71' from an R180 to an R200 20 years ago. Need to go in the opposite direction again. If I am reading correctly, I will need:

 

R180 mustache bar

R180 front diff mount

Maybe R180 to 4spd driveshaft? 

 

I assume the curved rear transverse crossmember can remain the "bowed" one thats needed for the R200. Anything else come to mind? A friend of mine is parting out his 240z (body is in terrible shape), so I should be able to get what I need. 

Edited by AydinZ71
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Most road racers run the R180 with some type of limited slip.  I run a R200 only because I have a couple of Quaife LSD's made for them.  You could probably even get away with a R160 for sprint races.  CV's are debatable.  Consensus is they have less drag.  But for durability I have seen as many S30 CV's fail (road racing) as u-joints.  For best reliability of either, best to have the angles as level as possible.  I have seen Z drag racers with drag slicks and 600+ HP run fine with some spicer u-joints.  They just made sure the squat on green light made the axles horizontal. But a CV will definitely work better and last longer at more extreme angles.   

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13 minutes ago, clarkspeed said:

Most road racers run the R180 with some type of limited slip.  I run a R200 only because I have a couple of Quaife LSD's made for them.  You could probably even get away with a R160 for sprint races.  CV's are debatable.  Consensus is they have less drag.  But for durability I have seen as many S30 CV's fail (road racing) as u-joints.  For best reliability of either, best to have the angles as level as possible.  I have seen Z drag racers with drag slicks and 600+ HP run fine with some spicer u-joints.  They just made sure the squat on green light made the axles horizontal. But a CV will definitely work better and last longer at more extreme angles.   

 

Thanks for the tips! so I expect my 3.545 Torsen r180 to be here next week, and Fritz's CV shafts arriving next month. The head will be out of the shop in 2 more weeks. She should be back on the road by the end of February. Looking forward to taking my lapses! I hope to get my car low enough to limit as much of the axle-cv angle as possible, as you mentioned. I have already eliminated some low points and cut about 1/2" of clearance. Il have to spend some time at the performance alignment shop tinkering with the coil overs to get the right height. 

 

I settled on a 10:1 static CR on the head for now. If I run a 1.75-2mm gasket, I drop down to 9.4, which will allow me to run ITS (thanks to your suggestion). With a prepared block in eventual development, I'm considering domed pistons to achieve the 12:1 needed to compete in EP. I'm really enjoying the process of upgrading the vehicles components strategically, even if its not perfect. I am learning so much about how these cars handle and perform again, I can't wait to test her out. 

 

I'm really learning quite a bit from the community. I appreciate all the advice. 

Edited by AydinZ71
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Regarding the front diff mount for the R180....you probably already know this; but the RT-style mount is pretty much universally accepted as the best all-round solution.  It can be used by itself (I've had mine in for the last 12 years, no issues), or can be used in combination with a lower differential mount (either OEM-style or aftermarket) -- typically only needed for high-power drag racing setups.  It's nice to be able to get rid of the stock lower diff mount, to free up a lot of space for exhaust tubing, especially in a lowered application.

 

The RT mounts are still available new from:  https://www.technoversions.com/DiffMount.html.

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1 hour ago, jhm said:

Regarding the front diff mount for the R180....you probably already know this; but the RT-style mount is pretty much universally accepted as the best all-round solution.  It can be used by itself (I've had mine in for the last 12 years, no issues), or can be used in combination with a lower differential mount (either OEM-style or aftermarket) -- typically only needed for high-power drag racing setups.  It's nice to be able to get rid of the stock lower diff mount, to free up a lot of space for exhaust tubing, especially in a lowered application.

 

The RT mounts are still available new from:  https://www.technoversions.com/DiffMount.html.

 

Hey thanks! honestly, i did not know about this! I don't think it was available in 2003 when I built my 71' L28et. On that car, the torque eventually wore-out the bottom differential mount (thanks to constantly pulling "up" on it). At that time, I was only aware of the solid bottom mount sold by MSA, which is what is still on that car. This is a much better solution since it retains a bushing of some type, and actually resists the upward torque reaction with compressive force, vs. tension. 

 

A few questions:

1) You have used only the top mount for 12 years? So, If I understand correctly, you have a small "gap" between the bottom of your diff and the front transverse link (forward control arm crossmember)? 

2) when you speak about creating more space for the exhaust, how do you achieve additional clearance? You would still need a cross member to compress the front control arm bushings, and provide bracing across the tunnel. Would this front mount be replaced with a modified one with a taller clearance? I have raw materials for a 2.75: 304SS exhaust, so I'm certainly interested creating more clearance! the most likely place to bottom-out on my car is the exhaust as it passes the bottom of the diff. I have the tools to fabricate this mount.

 

Really appreciate all the input!

 

-Aydin 

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5 hours ago, calZ said:

You can either cut the center section out of the diff mount and just retain the parts of it needed to hold the control arm bushing, or you can get something like this. 

 

https://technotoytuning.com/nissan/240z/fancy-rear-drop-mount-caps

 

These are a convenient solution, but I think the cross bracing serves an important purpose for body rigidity. If they made them in steel, id get a pair for the bushings, then weld square tube steel between them. Maybe the techno tubing set adds rigidity by some other means.

 

 

4 hours ago, NewZed said:

Doesn't the crossmember effectively "box" the driveline tunnel at the back of the car?  Thinking that it only serves as a spot to mount the diff and to clamp the control arm bushings might lead to unintended consequences.

 

image.png.f0c2db78a5d015dc011f96ba076962a4.png

 

I agree. If I can find the time, I will use the OEM bushing cap as a template to stencil from. Il use 14 gauge to transfer the template to, which will act as the "rib" for the bushing cap. Il find a pipe with a similar radius and hammer 18-gauge steel over it to make the radius. Then il tack the 18 gauge on one side (perpendicular to the 14 gauge ribs) and hammer the finished curvature in place, then weld them up. Once the caps are done, il weld rectangular or square tube steel between the two. Wont need to be that thick. 1.5-2" should do the trick. 

 

I just bought a fish-hook type scale so im going to start documenting the weight of some of these components. 

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@AydinZ71:  to answer your first question; yes, I am running the RT differential mount by itself....no lower front diff mount.  Have run this setup with no known issues for several years on both my current Z and my previous Z.  Several other member here have done similar installations with no issues. 

 

If going this route, it's important to use a mount that incorporates locking metal brackets internally....to prevent catastrophic failure.  The PU top mount from ES that Technoversions offers meets this rqmt.  I'm not pushing big power, but both cars have been set up with Hoosier RR slicks or A7s/R7s, so they obviously are withstanding repeated lateral loading.  The only issue with this arrangement that I've personally observed was a twin-turbo LS with large tire drag slicks -- the inner LCA mounting points got torn up after a number of hard launches.

 

I've reused the u-shaped brackets that secure the rearward LCA mounts, for the forward LCA inner mounts (i.e. bushing cap).  Or you can use aftermarket brackets like the ones @calZ suggested. 

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@calZ LOL, fair point :) I have been spending way too much time fabricating rust replacements, replacing roll bar mounts, and reinforcing the chassis. I think I'm getting carried away. I have been cutting quite a bit of weight by removing unnecessary components such as unused brackets and factory unibody-welded nuts. When incorporating monocoque structural components (cells, like tubes), you can reduce quite a bit of weight when compared to the resistance welded stamped steel. I may actually have to add-back weight to meet the 2150 lb spec., but at least then I can replace the weight as low as possible, and move the CG backwards to compensate for the natural understeer of the car. 

 

@jhm I think the top mount is brilliant! snapped one up yesterday with no hesitation. Had I known this was available, I would have gotten it years ago for my high-torque Z. I am not running very much torque on this application, but obviously needs to be robust enough for RR. I'm looking forward to it! Funny thing... he/she printed the shipping label within minutes of me making the purchase.

 

I have been posting quite a bit recently. It might be time to just start a dedicated thread for the car. 

Edited by AydinZ71
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