Opinion:Helical + 4.363

[float_6969]

Well I finally did it and got it all together. I now have a Helical LSD from an S15 Spec R Silvia and the ring and pinion from a CA18DET S13 Silvia. For those of you not familiar with the different gearing for the various differentials, the KA and SR powered S13 and S14's all got 4.083 diffs. The CA18DET S13 (JDM, UK got something totally different IIRC) got a 4.363. The JDM CA18DE got even lower gearing. Anyway, I've always felt that the diff gearing just wasn't right for the CA with the 4.083. I don't know what exactly it was, but it just wasn't right. Well after over a year of searching and gathering parts, I finally found a VLSD from a CA18DET on eGhey. I had found others, but was always bid sniped, or they went for more than I had at the time. When I got this one in, something seemed odd to me. First of all, it was evident that it had been opened up at some point, because the rear cover had RTV on it. Also, I couldn't turn the output shafts in opposite directions. The first thing I thought was that it was an open diff and had been welded. So I called the company and they told me to install it, and to call them if it had any problems. So I did, and the first thing I noticed was that at low speed, sharp turns, the diff made a lot of noise and wasn't smooth. Hmmmmm, I thought. So I pulled it back out and opened it up. Much to my delight, it had, what I believe to be, a Tomei 2 way clutch type LSD in it. I called the company back and told them everything was FINE! But now what do I do? I've got a clutch type LSD installed and ready to go, but I'm not a drifter. I know how to do it, and I like it, but it's not something I do regularly, nor do I plan to. The same thing applies to drag racing. I like doing every now and then, but not regularly. I'm more of an autocross guy. I started doing a lot of research and made a lot of posts on NICO, getting opinions and such. I finally decided that I wanted a Helical. I found a member, who also is a big seller on eBay, that was willing to trade me straight across. So now I've got a Helical, and the gearing I want. But it's not that easy either. First of all, the helical uses a different diameter bolt than the other types of LSD's available. Luckily NISMO makes a bolt for it. So after a couple of weeks I got that in. Now for the hard part. You can't just slap this together and go. You've got to set the gear mesh. This sucks. You essentially have to disassemble and reassemble the diff a bunch of times. I had been putting this off for quite some time and so the diff was setting in a box in the garage for a couple of months. Well this last week I got rambuncious and started messing with it. Well guess what, the gear mesh was fine! I didn't have to do crap with it! So last night I dropped it in, filled it up with 75-90 Synthetic Mobil 1 and tried it out....

Now the part you REALLY care about, what it's like. I'm not going to lie to you and tell you that it's a totally different car and that I'm ready to smoke some 500hp Ruf Porsche's. But I will tell you that the car now feels, well, RIGHT. Actually, SMOOTH, is a MUCH better word. Now that I've had back to back comparison, I realize now that the acceleration with the 4.083 diff felt rough. I know that sounds odd, but it's the truth. It now feels smooth. The acceleration feels just like it should. I'm VERY happy with it. As for the diff, it's hard to tell. I can feel that it's better than the VLSD, but the engagement is so un-obtrusive, that it's hard to tell if it's even doing anything. Don't get me wrong, it's working, but it just works so well! I'm going to have to learn to trust the car now. With the VLSD, it was almost worse than an open because it was sometimes unpredictable. That is not the case now. The diff now does EXACTLY what you would expect it to. Once again, much more SMOOTH. To me, this is the most important aspect of a cars performance, and driving in generally. With autocross, when hundredths of a second divide the 1st and 2nd place positions, being smooth and consistent is the most important thing. The car is going to be much easier to drive now, and will be much faster.

So if I had to do it again, would I spend the $300 that I spent on it? Of course. If I hadn't been so lucky, and had to spend $1,000 on it, would I still do it? Yes, but I'd be much skinnier for it.

Ryan Boatwright

[tyrannix]

*******, only had to pay $300

[float_6969]

LOL, yea, I got lucky...

[tyrannix]

well, my bearing will be coming in tomorrow, so i can pick it up on thursday, then assemble the new pumpkin, then ill be in the club (if a fitting shows up, i may even get my engine installed this weekend)

[top_secret]

so what are you doing with the tomei clutch diff? I'm looking for one and I already have vlsd so it should bolt right in.

[float_6969]

I don't have it anymore. I traded it for the HLSD + output shafts.

[oneruffryder42]

wow i have the 4.083 diff on my ca. feels good. but i did feel like the 5th gear got shorter. is this true can u help???

[float_6969]

hunh? Please explain that a little better.

[oneruffryder42]

just was wonderin when u had the 4.083 diff on your ca did the gears get shorter??? even more some in 5th gear?

[dvd]

so what revs on 5th does it take to get to 65mph now?

[oneruffryder42]

3.7

[dvd]

3.7

i meant to direct the question to float

[float_6969]

oneruffryder42- It felt like the car revved/accelerated easier/faster, and the car turns more RPMS going the same speed it did before. As far as the spacing between gears, no, it didn't feel any different. It shouldn't because that is all in the transmission.

dvd-I'm not sure because when you change the diff. gears, the speedo is way off. I can say that at about 70-75, I was turning about 3500-3700rpm, now I'm turning about 3900-4100rpm.

[biosehnsucht]

the 4.363 gears are 7% "faster" than the stock 4.08 gears. this is also the difference in speedo readings..

If you have the correct gear pinion tho its not a problem

[tyrannix]

if you are running a CA transmission, diff gear, and cluster, then it should be just as accurate as it was on the car it came from (you just need to do metric to standard math to figure out how fast you are going)

100 kph == 62.5 mph

(and think about this, the expressway in okinawa has an 80 kph limit, fastest road on the island, legally)

[dvd]

isnt it bad that we have to be reving past 3k on the freeway to go speed limit though =[

[oneruffryder42]

oneruffryder42- It felt like the car revved/accelerated easier/faster, and the car turns more RPMS going the same speed it did before. As far as the spacing between gears, no, it didn't feel any different. It shouldn't because that is all in the transmission. dvd-I'm not sure because when you change the diff. gears, the speedo is way off. I can say that at about 70-75, I was turning about 3500-3700rpm, now I'm turning about 3900-4100rpm.

thnaks for that info, i fell the same thing as u in the 70-75, I was turning about 3500-3700rpm, now I'm turning about 3900-4100rpm. thanks a lot

[biosehnsucht]

isnt it bad that we have to be reving past 3k on the freeway to go speed limit though =[

bah, just keeps you in the power band more for those quick passes

[float_6969]

isnt it bad that we have to be reving past 3k on the freeway to go speed limit though =[

Not a big deal. The CA seems pretty happy there IMHO....

[tyrannix]

did you get my email?

and i brought my pinion and empty pumpkin and all the bearings to a shop... turns out that to really play with the pinion and get it set correctly you need to assemble+dissassemble the whole thing a few times (because im putting in a new gearset) so this gets to be the first item on my car that somone else assembles for me :\

dropping off the lsd and cover and everything else tomorrow, should have it back and ready to install by fri

Not a big deal. The CA seems pretty happy there IMHO....