R200 LSD options/setup

Engine, Transmission and related drivetrain.
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jeffball610
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R200 LSD options/setup

Post by jeffball610 » 26 Nov 2018 09:31

So I've come to the conclusion that I will never find a stock longnose R200 LSD for a reasonable price, and I'm shopping for aftermarket solutions for my 4G63 powered 510. I've basically landed on the Tomei 2 way clutch unit, but I'd like to get others opinions on the topic. I mostly street drive my car, but I do autocross events and I'm hoping to make my first road course event in January. Is a 2 way the right choice, or should I look at 1.5 or even 1 way LSD options? This is going in a light weight chassis (lighter than any vehicle that came stock with an R200), so should I be concerned with the engagement setup? With a clutch type, you can swap out the stacks to get a particular engagement and slip. Would anyone recommend doing this over the "stock" setup? I have a feeling that the standard "out of the box" setup might be too harsh. I plan to do the install myself, so I'd like to have as much info as I can before proceeding. Also, since this is a longnose unit and the aftermarket options are for the shortnose units, who still makes the bolt sleeves to make this work? I think Z1 used to sell them, but I haven't seen anything lately.

I'm open to advice and options. I'd rather not get an OBX unit, but if a mechanical LSD is the best choice, I might take a chance. Are there any other concerns I should be aware of before taking the plunge?
1972 Datsun 510
7-bolt 4G63T, EVO 9 pistons & rods, Garrett GT3076R, "Flipped" Stock Intake Manifold, Toyota R154, Z31 R200 w/ CVs

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icehouse
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Re: R200 LSD options/setup

Post by icehouse » 26 Nov 2018 13:03

Why not just get the STI R180? R200's are so crazy big and heavy. Seems like overkill unless you are drag racing.
"People don't like it when shit doesn't match their rule of thumb." Sam

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jeffball610
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Re: R200 LSD options/setup

Post by jeffball610 » 26 Nov 2018 19:07

icehouse wrote:
26 Nov 2018 13:03
Why not just get the STI R180? R200's are so crazy big and heavy. Seems like overkill unless you are drag racing.
The first reason, is that it's already in the car. When I dreamt up this build, I wanted to make 400whp and be reliable without breaking parts. Now it's already installed, has beefy CV axles, 5-lug hubs, big brakes, and I shouldn't be able to break anything with only 300whp and 225 width tires.

I'm sure the R180 is a great option, but this is what I've got to work with.
1972 Datsun 510
7-bolt 4G63T, EVO 9 pistons & rods, Garrett GT3076R, "Flipped" Stock Intake Manifold, Toyota R154, Z31 R200 w/ CVs

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JordanTr
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Re: R200 LSD options/setup

Post by JordanTr » 27 Nov 2018 05:51

I’ve put about 1 mile on my car with a 1.5 LSD and I can say it is definitely nicer and tighter than a vLSD. I put an ATS diff in and measured the static breakaway torque at around 70 ftlb which is pretty tight.

I went with 1.5 because it should be less tail happy than a 2 way.

You certainly don’t want to re-engineer that whole rear end again with an R180!

Make sure you get an R200 from post 7/86 or 9/86 (can’t remember!) so you get 12mm ring gear bolts so you don’t have to mess around with sleeves etc. IIRC this limits you to mostly 3.7 and 3.9 and maybe a couple months of 3.5 open in the late 86 turbos.
Jordan | '72 2 door KA project | '94 240sx RB26DETT | '97 Silvia RB25DET | '90 Audi 90 Quattro 20V (DD)

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bertvorgon
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Re: R200 LSD options/setup

Post by bertvorgon » 27 Nov 2018 11:53

My one comment, based on the VSLD in my G35 ( similar to the R200) is that it "lags" before full engagement. It is very noticeable to me, s I do drive hard at times, and, can compare it to my LSD in my 510 ( Nissan clutch pack).

I really notice it on toss in, where you EXPECT the damn thing to hook up, yet the rear still feels like it wants to come around...then it kinda locks up, most disconcerting on one of my routes where the road is narrow and have planned my arc through the corner...and my brain is going.....is it going to hook up or not.....
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

Keith Law
1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer

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jeffball610
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Re: R200 LSD options/setup

Post by jeffball610 » 27 Nov 2018 20:38

JordanTr wrote:
27 Nov 2018 05:51
I put an ATS diff in and measured the static breakaway torque at around 70 ftlb which is pretty tight.
How do you measure breakaway torque? Obviously I'll look it up, but that I'd see how you did it.
JordanTr wrote:
27 Nov 2018 05:51
Make sure you get an R200 from post 7/86 or 9/86 (can’t remember!) so you get 12mm ring gear bolts so you don’t have to mess around with sleeves etc. IIRC this limits you to mostly 3.7 and 3.9 and maybe a couple months of 3.5 open in the late 86 turbos.
I'll take a closer look at the spare unit I have. I know it's a 3.7. I think I pulled it from an 87 300ZX non turbo. If it has the 12mm bolts, I think I'm good. I just remember seeing something years ago about the bolts being a different size in the longnose vs. the shortnose R200 (specifically the 240SX)
1972 Datsun 510
7-bolt 4G63T, EVO 9 pistons & rods, Garrett GT3076R, "Flipped" Stock Intake Manifold, Toyota R154, Z31 R200 w/ CVs

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JordanTr
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Re: R200 LSD options/setup

Post by JordanTr » 28 Nov 2018 07:30

I built a little adapter that bolts onto the 3x2 bolt pattern and has a big nut at the center. I bolt it onto a 240sx output shaft and use a second output shaft in the other side of the diff center. I clamp one output shaft in the vice and rotate the adapter with a torque wrench. I used a click type torque wrench so it isn’t totally accurate but my bending beam torque wrench is too small for this task.

Ya that sounds like it should have 12mm bolts but it’s worth a double check. Late longnose diffs have the same 12mm bolts as the S/R/Z chassis cars so that’s what you want.
Jordan | '72 2 door KA project | '94 240sx RB26DETT | '97 Silvia RB25DET | '90 Audi 90 Quattro 20V (DD)

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broke
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Re: R200 LSD options/setup

Post by broke » 09 Dec 2018 14:22

I have a R31 CLSD with Nismo clutch packs so didn't need any bolt spacers. A friend bought a used Cusco RS diff for his and it was a much, much nicer looking unit than the Nissan one and could be set up to be 1, 1.5 or 2 way. Adjustment of breakaway torque on it was by the order you stacked the plates in.

It did have about 13mm bolt holes though, so if you do go for a Jap aftermarket unit you might want to leave buying the the bolts and spacers until after you have the LSD in your hands.
The IDx 10 concept is based on the 510 in the same way that the urinating I was doing last night was based on a 30 yr old single-malt scotch.
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jeffball610
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Re: R200 LSD options/setup

Post by jeffball610 » 01 Jan 2019 11:30

So I broke down and bought a Tomei 1.5 way. However, their doesn't seem to be any good info on setting up an LSD. I have the specs for the Tomei's initial toque and there's even a drawing of the clutch plate set up, but they only have directions on how to increase initial torque, not reduce it. That being said, I'm not sure what torque figure I should be going for. The 510 is a pretty light chassis, and it's not like I'll be making 1000hp on big sticky tires, so I'm assuming a lower initial torque set up than "stock" is what I should be going for.

I'm trying to compare numbers between the R200 and smaller cars like the Miata to see if it makes sense. However, I don't know if the Miata numbers are for stock N/A setups, or something more. Does engine power mean anything in an LSD? Is it all friction from tires and rolling mass? Does anyone have a solid number to build from?
1972 Datsun 510
7-bolt 4G63T, EVO 9 pistons & rods, Garrett GT3076R, "Flipped" Stock Intake Manifold, Toyota R154, Z31 R200 w/ CVs

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JordanTr
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Re: R200 LSD options/setup

Post by JordanTr » 01 Jan 2019 19:19

I've only been up and down the (long) driveway a couple times with the diff and it seems to be fine at 70 ft-lb.

What specs does Tomei say?

I would just put a whole bottle of the Redline limited slip additive in (that's about double the treat rate) and use that for rev 1. If that proves to be a tire skipping disaster then you could look at machining some meat off of the inner parts to reduce the pressure of the clutches.

I seem to recall Subaru's LSDs were set up with 45ish lbs of static breakaway torque. Guys seem to be happy with those in 510's.

If you really want a number, I would guess 45-60 ft-lbs is a conservative starting point. Closer to 70 ft-lbs for something aggressive? Keep in mind that the cam engagement on or off throttle is really what's doing the work for you.

If you are going to bench test it, make sure it's all lubed up!

HTH
Jordan | '72 2 door KA project | '94 240sx RB26DETT | '97 Silvia RB25DET | '90 Audi 90 Quattro 20V (DD)

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Byron510
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Re: R200 LSD options/setup

Post by Byron510 » 02 Jan 2019 00:20

I had a local ‘Specialist ‘ set up my R190 diff years ago for a street car. The thing was set to 75 lb break-away. It may have well be a welded diff. On new A032’s at the time, I couldn’t get the diff to actually be a diff. As noted, it may have well be welded.
So, I took the opportunity to learn to set a diff up myself. Tried a few different set ups and settled at a hair over 50 lbs and it felt quite good. A few years later I shimmed up my replacement R180 Precision Gear diff the same way, actually ended up at 43 lbs, and I’m still happy with it. I checked it last year and it’s now 41 lbs, still going good.

Just my thoughts on a primarily street car with the odd track day and auto X thrown in for good measure.

Byron
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because the opposite never works.

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bertvorgon
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Re: R200 LSD options/setup

Post by bertvorgon » 02 Jan 2019 08:08

Just saw this thread. I too ran my diff at around 45 lbs breakaway, on race tires and of course street duty, worked just awesome.

After seeing this thread I will check mine again and see where it is at after some 37 years of use.
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

Keith Law
1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer

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jeffball610
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Re: R200 LSD options/setup

Post by jeffball610 » 02 Jan 2019 21:14

I'm hoping the calculator I used is wrong. Tomei says initial setup should be between 16.5-18.5 kg/m. If that's right, it should be around 120 lb/ft :shock:

This is for a "IA" diff meant for a stock open diff 240SX and pretty much anything with an R200. http://www.tomeiusa.com/manuals/pdf/lsd.pdf

The units meant for Miatas and such are around 43-53 lb/ft which seems much more inline with what you all are saying. The directions on shimming up to stiffen it, add 1 extra "spacer" to tighten things up. I'll measure what the clutch plates are and see if it's possible to simply remove one to lower the torque. Some of the other diffs they make list replacing a plate or two with ones that are 0.1mm thicker. The extra 0.2mm translates into a 10% stiffer torque increase.

Looking at the application list, it does seem that the BRZ/FRS application has the same basic torque settings as mine though. That might be a good sign.

In any case, it looks like I'll be contacting some professional race shops to see what is possible. Maybe I'm going about this all wrong, but this seems way more difficult than it should be. Tomei doesn't even have a customer service contact info (just found it at the bottom of the applications page)
1972 Datsun 510
7-bolt 4G63T, EVO 9 pistons & rods, Garrett GT3076R, "Flipped" Stock Intake Manifold, Toyota R154, Z31 R200 w/ CVs

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jeffball610
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Re: R200 LSD options/setup

Post by jeffball610 » 07 Jan 2019 18:42

I got my Tomei unit today. Seems like a solid unit. The direction booklet that comes with it doesn't have any info that I don't already have. I'm still unsure of how to reduce the initial torque, because no one likes to answer phones or return calls. I don't see any info on the internet either and I've yet to see anyone install a Tomei LSD that does more than drop it in. I hate being the one to break new ground, but a man has to do what he's got to do.
1972 Datsun 510
7-bolt 4G63T, EVO 9 pistons & rods, Garrett GT3076R, "Flipped" Stock Intake Manifold, Toyota R154, Z31 R200 w/ CVs

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jeffball610
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Re: R200 LSD options/setup

Post by jeffball610 » 08 Jan 2019 16:58

Small update. I spoke with Tomei USA and they said there might be a way. They are contacting Tomei Japan to confirm.

My thought was to reduce the contact between inner and out clutches. Currently there are 4 inner and 4 outer clutches on each side. That gives me 7 points of contact on each side. If I swap around the clutches to have 2 of each touching (2 inner and then 2 outer etc) I can reduce the contact down to 3 points.
Image
If my math is right, that should be a 62% reduction in surface area and effectively giving me 9.57kg/m or about 69ft/lbs which is what everyone seems to be telling me to shoot for.

I seriously have no idea if this will work, as I have zero experience with diffs or anything of this nature. If anyone has any good ideas, let me know.
1972 Datsun 510
7-bolt 4G63T, EVO 9 pistons & rods, Garrett GT3076R, "Flipped" Stock Intake Manifold, Toyota R154, Z31 R200 w/ CVs

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