Tag Archives: 4.3 ring and pinion

Bringing Up the Rear Part I: 4.3 Equipped Rear Differential in Progress

2 Aug


(Warning – this is a long one)

One of the weird projects I got started with on my 350Z has been installing a 4.3 ring and pinion. The car currently sports a 3.9 ring and pinion mated to a Cusco RS LSD (stock ring and pinion was 3.54 for manual transmssion cars). I figured the 4.3 would nicely compliment the high rpm’s that my engine turns (current redline is 8400), and give the car alot more punch all through the rev range, plus it would be another something to help set the car apart from the rest. It was only after acquiring all the parts that I realized just how difficult this would be!

I started by picking up a spare pumpkin and set to work on dismantling it. That proved to be easier said than done. I don’t know what this rear went through, but the pinion flange would not come off at all. We tried torches, freezing it then torching it, even a 20 ton press – it wouldn’t budge. Strike 1. If at first you don’t success, and the BFH doesn’t work, you go to plan B.

I was able to pick up a spare, empty pumpkin from my buddy Gio (who has a badass G35 coupe that we’ve featured before). With the spare pumpkin in hand, it was time to get to work on piecing this thing together. I decided this time we would try a Quaife LSD. I had a spare one at the shop that had been shipped to a customer but never used. See, he had an auto, and Quiafe mistakenly sent us one one for a manual car, which we sent to him. He tried to install it but it obviously wouldn’t work. So, we sent over the correct one and I decided to keep the returned unit for myself. It had never been used, and I figured I’d rather try it for my own car, rather than take a hit selling it. This took place before Quaife released their drop in differential for factory VLSD equipped cars, so the unit I am using is technically for a base model. No big deal though. A quick call to Nissan and I had the base model output shafts on their way, along with fresh bearings, seals, ring gear bolts – everything needed for the install.

So where was the problem? The ring and pinion itself! See, the 4.3 was sold as an upgrade for 240sx and naturally aspirated 300zx’s. I believe these originally came stock in the S13 180sx in Japan (someone correct me if I’m wrong). As it turns out, while these cars all used an R200 rear (350Z included), there are some differences. I knew this going in, I was just hoping it wouldn’t affect the swap. As it turns out, it did. The problem is basically 3 fold. First, the ring gear. The “old” R200’s use a smaller bolt vs newer R200 in the 350z. Thankfully the bolt hole spacing is the same, so acquiring the new bolts from Nissan easily solves this. The pinion issue is more difficult, and really required some out of the box thinking. First off, the pinion length is at least the same on the old vs new R200….thankfully, something went our way! The problem is that the old R200 uses a thinner diameter pinion shaft vs the later R200. This creates 2 issues. First, the rear pinion bearing for the Z won’t fit, and second, the flange for the driveshaft that goes on the end of the pinion is different. At this point, I decided I was in way over my head, and enlisted the help of an expert. Enter my buddy Ben from Puddymod Racing. Ben is widely known on the S2000 forums as the go to guy when it comes to rear end assembly. He’s meticulous when it comes to this stuff, and he knows the ins and outs of properly putting stuff together. Plus, he’s not afraid of funky projects such as this (his own S2000 runs a bit of an oddball setup). So I spoke to Ben at length about the hodgepodge of stuff we had, and he enthusiastically said to “ship it all down, we’ll make it work”. And off it went.

Fast forward a couple months and there is light at the end of the tunnel. Ben’s been tied up with his day to day stuff, and I’ve been going through the trials and tribulations of the now-abandoned ITB project. Ben contacted me today with some good news and a bit of a “how we did it”.

First, the bearing issue. You have a pumpkin that needs a pinion bearing with a specific outer diameter. The Nissan part for the job for the 350Z fulfills this need, but it’s inner diameter is too big for the pinion gear for the 4.3 setup. The pinion gear that would go with the 4.3 setup has the right inner diameter, but the wrong outer diameter. The solution? Sleeves. Basically what is done is your building up the surface of the pinion shaft so it will accept the larger inner diameter Nissan pinion bearing for the Z. Check the picture above and you’ll see the pinion being worked on.

Part of the process Ben is doing for me is not only deburring the ring and pinion, but also microfinishing them as well as cryo treating. Everything is fully blueprinted, so the tolerences are kept in check, just as you would do to a properly built engine.

The second issue is of course the flange. This is easier to solve but still needs some customization. I’ll post some pictures and details in the next installment.

The labor associated with this project is pretty insane. I’d say 20-30 hours when it’s all said and done…and that doesn’t include R&R of the pumpkin itself. As such, I don’t see it being a feasible thing for us to offer, unless someone has the right engine setup and deep pockets. y reason for going forward with it was pretty simple. I had already invested $ in spare pumpkin #1, and I had the Quaife differential. I had also purchased the ring and pinion from NISMO. At that point, I had already spent the $ on the hardware, that simply ditching it was not really an option.

Next up I’ll post some pics of the finished product, and go into a bit of detail on the pinion flange. This is going to be topped off with the SPL Solid Rear Differential Bushings …maybe even Whitelines Urethane rear subframe set too