Topic: zzzzzzzzz=The Room for Fairlady Z=zzzzzzzzz

[คุณใหญ่]

ต่อ
ใช้ 4.3 ของ R230

[Pun]

ส่วนใหญ่ใช้ตรงรุ่นไม่แปลงใช่ไหมครับ แลวจะหาซื้อที่ไหนได้ครับ

[คุณใหญ่]

เซียงกง บางนา หรือ รองเมือง

บอกก่อน ถ้าหา R180 R200
ก็เดินเมื่อยหน่อย

[sucharit]

ส่วนใหญ่ใช้ตรงรุ่นไม่แปลงใช่ไหมครับ แลวจะหาซื้อที่ไหนได้ครับ

ของผมใช้ตรงรุ่น ....

เคยลองแค่เอา R200 มาใส่อยู่ครั้งนึง ..

ไม่ถูกใจ มีอาการไม่ปกติตอนขับมีเสียงและไม่เนียน

ผมว่าช่วงล่างแซทสแตนดาร์ทที่สมบูรณ์ขับดีมาก เกาะถนน นิ่ง เงียบ (ตามแบบรถโบราณนะ )

แต่ถ้าไม่สมบูรณ์หรือแปลงไม่ดีพอ ขับไม่ดีเลยครับ

[sucharit]

ซ่อมที .. เห่อที

เมื่อบ่ายขับเจ้าแซทไปซ้อมกอล์ฟ ...

ขับเพลินดี .. แอร์เย็น .. เสียงเพราะ

[sucharit]

เปลี่ยนไดชาร์ทแล้วดูเตี้ยลงอย่างไงก็ไม่รู้ ...

ขับคันนี้ ทิปเด็กยกกระเป๋าน้อยเเล้วไม่ถูกค้อน 25 บาท

รถเก๋า .. ป๋าตังค์น้อยยยย

[sucharit]

ขากลับเข้าเติมน้ำมัน ... กันเหนียว

350 บาทเต็มถังซะแล้ว .. ลืมไปว่าก่อนเข้าอู่เพิ่งเติมเต็ม

นานๆขับทีก็ดีเหมือนกันนะ ...

ว่างเมื่อไหร่จะไปเปลี่ยนไฟท้ายที่มีซะหน่อย จะได้ตรงรุ่น ..

ตอนป๋าใหญ่ไปพม่า .. มีไฟท้ายมาขาย .. Euro spect ใหม่เอี่ยม 1100 US รวมค่าส่งคงไม่เกิน 1300 ..

อยากได้จี้ด .. ดีที่ป๋าใหญ่ไม่อยู่ เลยประหยัดไปซะ

( เกือบห้าหมื่นบาทแน่ะ )

[OKUMI RT]

ทำไมวันนี้สีเงาผิดปรกติ 

[sucharit]

ทำไมวันนี้สีเงาผิดปรกติ 

มาจากอู่ยังไม่ได้ทำอะไร

สงสัยช่างนะเอาน้ำมันหมูทาไว้มั้งครับ

[คุณใหญ่]

ขับคันนี้ ทิปเด็กยกกระเป๋าน้อยเเล้วไม่ถูกค้อน 25 บาท

รถเก๋า .. ป๋าตังค์น้อยยยย

ระวังเด็ก เค้าจะว่า เลขทะเบียนรถ
แพงกว่ารถ นะ

[speeddproshop]

เอามาฝากครับ เผื่อเป็น Idea

The C4 Corvette IRS Swap
 
 
Despite a lot of work setting up the IRS in the Datsun 240Z to get it to launch hard at the drag strip, I still felt I had a need to make a modification. Before deciding to make the switch to the C4 IRS, the Datsun IRS was made up of the following components:

Stock 71 strut with the spring perch raised 2" and cut-down 280ZX 2+2 springs. This is the JTR mod
Tokico Illumina 5-way adjustable shocks
82-83 280ZX rear brakes with the Maxima brackets and steel-braided lines (see adaptor pic below)
280Z stub axles (strongest that will fit in the 240Z hub) with longer, HD wheel studs
R-200 differential with 3.54:1 ratio and welded spider gears
280ZXT CV axles
An adaptor of my design to fit the CVs to the 280Z companion flange
Contact Ross at Modern Motorsports, http://www.modern-motorsports.com if you interested in this adaptor, big brake kits or other custom-made components for Z cars
3" o.d. custom-made driveshaft.
IMO, to date, this is the strongest setup that can be installed in a 1st-gen Z with stock Nissan components. The "weak points" in this setup are the CVs and the stub axles. However, when I refer to it being weak, I am thinking of a Hybrid Z with a stout V-8 or in my case, a Buick V-6 turbo with about 500 lb/ft of torque, launching hard off the line at a drag strip. Anything less or one not driven that hard should be fine with this setup. Custom-made CVs for this setup (~$500) and the R-230 swap could prove to be better. However, the R-230 swap using the same CVs and stub axles has no advantage other than an LSD because there is no issue with the strength of the R-200. It is important to remember that in most all cases, such a setup is being put together with used parts and you have to deal with the luck of the draw. E.g., stub axles and a R-200 pulled from a 75 280Z is 26 yrs old and the diff might still have the original lube in it.

 

[speeddproshop]

So, why did I need to switch (other than wanting an engineering exercise. LOL)?

I have been running drag radials and the car rockets off the line with a freaky best 60' of 1.55 with BFGs and consistent low-mid 1.60s with Nittos (both 275/50-15 on 15x8 Welds). Despite that, I am not launching the car as hard as I could and have nary a trace of wheel spin off the line. However, I have already broken the original driveshaft and a CV and had a stock of spare CVs, just in case. Would like to eventually step up to a DOT-slick and launch harder with confidence
The Buick V-6 turbo is stock and it is pointless spinning it pass 5200 RPMs. With the 3.54:1 ratio, I was topping out 3rd at about 113mph (BTW, the Nittos are much shorter than advertised) and had to shift into OD, which is .67:1 and drops the RPMs down to about 3500!!!. That causes the Max Effort chip to fall out of power mode, I start getting knock and the car falls on its face. I need to avoid the 3-4 shift with a final drive that will allow at least 125mph in 3rd .
Alternatives

Stick with the Nissan IRS but swap out the 3.54s for 3.36s and build up the engine to run higher RPMs. Sounds enticing and this is the route others have chosen. 3.36s are rare and expensive and if I went this route I would also want a LSD. I estimate $1,000 for the R&P, LSD and diff setup with new bearings and I am still left with the "weak points". Building up the engine for more RPMs implies more HP (else what was the point?) to exploit the weak points.
Install a solid rear end. I almost went this route but it would have been very expensive, with either a Ford 9" or built-up 8.8" with LSD and the correct ratio. Then there are the suspension links, Panhard rod and coilovers. Perfect setup for drag racing but there is still a lot of street driving in the car and I just had a hard time not keeping an IRS
I also looked at other OEM IRS', specifically the Ford 8.8 and the SupraTT. The Ford would have to narrowed and was a little more difficult. It also would have needed beefier CVs ($500/pr) and a R&P swap to get the ratio I needed. the SupraTT was my first choice but I could not find a compete IRS for sale.

[speeddproshop]

The Corvette IRS

I am sure there are other Z cars out there with a Corvette IRS, but to my knowledge, there are only 2 and I want to say thanks to both for taking the time to help me understand the swap and finalize the decision. You know who you are. I will jump ahead and say after getting the IRS and sizing it up, I wonder why others have not done this. What drove the final decision was an opportunity to purchase the IRS at a very reasonable price AND someone purchasing my entire Z IRS to help fund this project. The particular unit I purchased is a DANA36 with a 3.07:1 ratio from an '84. So, what are the pros and cons of doing this swap? The obvious con is that there is no kit and you have to be willing to pay someone to do a lot of fabrication if you are unable to do it yourself. For me, the pros as I see it so far are:

With the 3.07:1 LSD, I get a LSD and the ratio to keep me out of OD for a long while, maybe forever
The C4 IRS is all aluminum, except for the rotors and some minor items. Total weight savings over the Nissan IRS is 80lbs!! Picking up the C4 diff compared to the R-200 is shocking.
11.4" brakes. 'nuff said, but now I have to get bigger front brakes. Darn.
Where the Nissan IRS had no adjustments, the C4 IRS has camber and toe adjustment. There is no doubt the car will handle better
With very little effort, it has a show car appearance
With less weight and a taller ratio, I have a feeling I can improve on the 23mpg highway mileage
Last, but not least, FOR ME, it was the least expensive of the alternatives. At least it will be if I do not get carried away.




Here is a frontal view of the C4 IRS. The thing that jumps out at you are the beefy 3.5" axles. Below the axles are 2 arms that go from the bottom of the diff to the bottom of the hub and using a cam on the diff end, adjusts camber. The 2 items with the 3 holes are referred to as "dog bones" but are equivalent to suspension links you see on hot rods.




From the rear you see a massive triangulated bar that is used to hang the IRS, similar to the "moustache bar" on a Z. However, that bar also servers as the diff rear cover and the mount point for a couple of pieces. From the top you see a piece that looks like a large wheel cylinder with 2 rods that attach to the top of the hub. The ends are similar to a tie-rod but it is passive and serves to adjust the toe. Below that you see the transverse, monoleaf, composite spring which weighs about 5lbs!

[speeddproshop]

The measured distance from the outside edges of the tires with the Nissan IRS was 66". That was with 275/50-15 tires on 15x8 Weld wheels with a 4.5" backspace. Keep in mind my Z has fender flares. My objective was to end up with the same basic dimensions. The C4 IRS, measured the same way, was 70" with 245/50-16s on 16x8.5 wheels with a 32mm offset. That means there is approximately 3" from the inside mount point of the wheel to the outside edge. Add about .5" for sidewall bulge to make it 3.5" on each side and a total of 7" for both sides, making the hub to hub width of the IRS 63". Way too wide for a stock-fendered Z and leaving me only 1.5" to play with on each side. I decided to narrow the entire unit 3" which would give me 3" on each side and with late Z-28 or Trans-Am wheels that should solve that problem. Those wheels are 16x8 with about a 6+" backspace. Will consider something "fancier" at a later time.

Narrowing the C4 IRS at first would seem daunting, but looking carefully at the unit, it ended up being fairly simple. The following items need to narrowed:

Axles - cut off one end, take out 1.5" and re-weld. Actual cost - $110. A good aluminum welder is not cheap
Toe adjustment rods - as stated earlier, these rods are passive, so each rod was sectioned and re-welded. Actual cost - $40
Camber adjustment arms - these are cast aluminum and could probably be cut and welded but I elected to go with a steel replacement custom-built to my specs with adjustable ends. Actual cost - $110/pr. This item was purchased from Vette Products and Products (VBP) in St Petersburg, FL.
Leaf Spring -  I will be getting a custom-made spring for the length I need. It will also have a spring rate to match the rear weight of the Z Vs the heavier Corvette. Actual cost - $275 or $425 if I add a trick component that allows ride height adjustment for each side. The springs are also available from VBP. I also have the option of eliminating the OEM leaf spring and shocks setup and converting the IRS to coilover shocks.

[speeddproshop]

Installation

Here then is a summary of the installation steps I have laid out. As the project progresses, I will keep updating this page and since I have installed the unit 100 times already in my head, I do not expect any deviations. Yeah, RIGHT! Knock, Knock. "Who's there?"  " A Mr. Murphy to see you".

Before pulling the Nissan IRS, make some reference and positioning points. I marked the center of the rear track on the horizantal frame rail, a vertical centerline of the hubs and a horizantal centerline of the hubs at rest. You will see those as little arrows, some on blue tape
After pulling the Nissan IRS, position the C4 IRS to get a feel for how it will fit. I almost fell out when I did this because, other than the width, everything lined up like I hoped
Determine how much the unit needs to be narrowed
Determine mount points for:  (wherever possible, mount points will be on a frame rail)
Triangulated bar
Suspension links (dog bones)
Front x-member
Design and fabricate hanger for triangulated bar so unit could be hung in place to design and fabricate front x-member
Have axles, toe rods and camber adjustment arms narrowed
Determine exact width of leaf spring
Finalize assembly with custom leaf spring and mount completed unit  (N/A with switch to coilovers)
Determine where/how suspension link ends will be mounted and fabricate as required. I see this as the biggest challenge
Weld top shock mount to frame rail once final position is determined  (N/A with switch to coilovers)
Ensure driveshaft will have the proper angle and modify driveshaft as required
Redo brake lines from Tee
Put rest of car back together: fuel cell, fuel pump/filter/lines, cover for spare tire well, rear hatch, exhaust system
Have final alignment done.
Obviously not a project for the timid or mechanically-challenged. Asked myself a couple of times just what in the hell did I get into, BUT, it would not be a challenge if I did not ask that.

[speeddproshop]

On the left, the Nissan IRS is out and some reference points marked. On the right is the initial trial fit. Nothing is connected and the IRS is just resting on the jack, but it already looks at home.

[speeddproshop]

 Here you see the suspension link hanging. Final position will have the 2 bars about parallel and the mount point in the lower inside corner of the fender well. That part of the fender well will need to be trimmed and a solid mount point fabbed and welded in. Also note that the mounting eyelet of the triangulated bar ends up at the bottom of the strut tower and does not protrude into the wheel well so it will not have to be modified. The hanger will be fabbed and welded to the frame rail at the bottom of the strut tower well.

[speeddproshop]

Here is one of those points when I questioned what the hell I got myself into. Here you can see the fabbed hanger in position on the bottom-right.

[speeddproshop]

Here you see some minor sheet metal trimmed from the base of the strut tower well and the hanger welded in place on the frame rail. A little sanding, rounding off the lower edges and paint should pretty it up nicely. The entire unit was made of  3/16" flat. The horizantal piece welded to the frame rail is 7"x2". The 2 side pieces are 6"x3" spaced 2 5/8" apart. The other piece adds rigidity. Actual cost - $70/pr

[speeddproshop]

The Biggest Challenge

The next step was the big challenge, connecting the suspension links.

YIKES!! Up to this point, the only mod to the car was to cut off the big bolts for the moustache bar to make room for the hanger picture here. At first, that hole was frightening but after seeing what others have done to their cars to make similar modifications, I realize I just "nicked" mine. I did have to cut into the frame rail at the bottom of the hole but it was a very short piece where it ended. I will replaced it with a much beefier piece. This is the extent of "cutting up" the car to make this IRS fit and that I think is quite amazing. This picture also gives a good point of reference for where the coilovers will be installed, so I will discuss that now. If you refer back to the picture that shows the entire unit from the front, you see the original mount point for the shocks. In this picture you will notice the shiny portion of the hub at 11:00 behind the rotor lines up perfectly with the center of the strut tower. I have decided to use a coilover shock that will have its bottom mounted on top of the hub and the top will be mounted in the original mount location at the top of the strut tower. More details on this when I get the shocks and do the installation.

[speeddproshop]

On the left, here is what the link looks like from inside the car and the hole does not look so bad from this angle, LOL. On the right was the fabrication of a mounting bracket with substantial bracing to take the expected forces from the suspension, especially under hard launches. I will add some more bracing but have not decided how/where at this point. Once I have the first test session at the track and check for stress in the welds, the area will be dressed up.

[speeddproshop]

Shocks and Springs

As previously stated, I decided to forego the C-5 monoleaf spring and standard shock and go with coilovers. This is not uncommon, but I decided to mount the top of the shock in the Z-car strut tower and the bottom of the shock on top of the IRS hub. By my measurement, this required a shock with an extended length of 15.5". Most of the well-known shock companies have a limited choice in custom shocks and a 15.5" shock usually has ~3.5" shock travel and a 10" spring. I chose the Aldan Shock Absorber Co because they are a custom shock manufacturer. Aldans shock are made from an aluminum billet and has a good reputation in the custom hotrod and drag racing worlds.

 After listening to my requirements, they made me a pair of shocks with a 15.5" extended length, 4.5" shock travel, 2.5"/160# spring with a 12" length and adjustable rebound, $380/pr/shipped. The key to getting a 12" on a 15.5" shock was extending the threads as far down on the body as possible. here you see the shock with a very simple top mount bracket to bolt it up to the Z car strut tower.

 

[speeddproshop]

Here you see how the shocks is attached to the hub and positioned to fit up into the stock strut tower. The shock does not have a bump stop so I made one using the Vette bumpstop. Here you also see a shot of the custom toe rod mentioned below.

 

[speeddproshop]

Driving Impressions

Mounted up the Z-28 "Salad-Shooter" wheels with 255/50-16 BFG drag radials. BTW, these wheels weigh at about 17lbs each. Took the car for its first test drive, made it one block and panicked. Felt like the rear wheels were about to fall off. Turns out the inner ends of the toe adjustment rods were so badly worn, I could move them in/out about 1/16". That translated to the rear wheels wobbling badly. Mad with myself for missing that. VBP sells a custom replacement with heim-jointed ends for $260/pr. I decided to make my own and here is the results.

[speeddproshop]

I had a difficult time finding a tapered rod to fit the IRS. GM, in its wisdom, makes all the front-ends with the same taper but the C4 IRS is different and unique. Instead of a taper, I drilled out the tapered hole in the hub to 7/8" and inserted a 5/8" id bushing (7/8" od). I then used a 4" 5/8" bolt with a stack of spacers on both sides of the heim joint. Repositioning the spacers that sandwiches the heim joint changes the angle of the rod and therefore the bumpsteer. The center bracket is make out of 1/4" flat with spacers to equal the thickness of the original. The rods are 5/8" aluminum tubes with threaded ends and the heim joints are Aurora 5/8" with LH and RH threads. The rods and joints were purchased from Coleman Racing.

With the IRS aligned, the setup really feels impressive. It is going to take a little while to get used to it. With the front of the diff mounted solid (my choice) and every rubber replaced with polyurethane, this thing is incredibly tight compared to the stock Nissan IRS. It is also a little noisier, as expected. Initial tests launching the car lights up the grin-o-meter. A 2psi launch on the transbrake with 15psi boost, lights up the 255/50-16 ZR tires for 250' !!! Of course, that is totally useless, but the important point is that the car launches straight, with no vibrations or dramatics. Will find out how well it really works at the strip with the drag radials, 7psi launch and 24psi boost.