DIY Installation: Rear Differential Bushing

You’re only as strong as your weakest link. To that end, there are many small changes you can make that will literally transform how your car performs.

One issue that plagues the Z and G is rear wheel hop. Some try to “cure” it with an aftermarket differential, only to find the problem magnified. The solution are some rather simple looking, but ultra effective bushing replacements. The Z and G have a rather conventional differential (aka the pumpkin, because of its shape…even though on these cars, it looks more like a squash) mounting system with 2 “ears” at the front and a single, large rear bushing. The front set of bushings are mounted into the pumpkin casing itself. The rear bushing, however is mounted in the subframe. All these bushings are liquid filled rubber, encased in an aluminum shell. OEM’s use this style because its reasonably stiff and strong, but able to dampen out noise and road imperfections. The whole rear differential assembly weighs about 90 lbs, so those bushings are under tremendous strain as the car squats, launches and turns. What many owners find is the rear bushing eventually starts to weep its liquid out, eliminating its effectiveness. The tell tale signs are a black stain on the rear subframe. The subject car here didn’t have that issue, but that does not make the result any less awesome. On this car, the front bushings had previously been replaced with the solid SPL units several years ago. The rear most bushing never was done due to time constraints at the time. But that’s what is being tackled here.

Step one involves using some PB Blast and getting under the car and soaking the bushings. This will cut through any surface rust that may have developed, and give the factory bushings some slickness to help in its removal. Step 1.2 starts with unbolting the mid pipe, and loosening the rear swaybar brackets. This lets the bar spin upside down, granting you more room to work. The pumpkin comes out without the bracket removal but you will appreciate the room when reinstalling it. Next, remove the 4 bolts that connect the rear driveshaft yoke to the pinion flange. Next up, unbolt the output shafts from the axles. The axles will dangle in place which is fine. Next step is drain the differential fluid via the side drain bolt. From there, unbolt the speed sensors at either side. Be careful! your speedometer and ABS use these, so unbolt em and tuck them up top. If you can reach it, use a pair of needlenose pliers and remove the breather hose at the top of the pumpkin. Next, you’ve got the 2 14mm bolts at the front of the pumpkin, and the rear nut that is “in” the bushing in the rear subframe. A tranny jack and a friend are very helpful here. 90 lbs is a lot and this isn’t something you want to drop!

Rear pumpkin with axles disconnected:

Next up is the big rear cylindrical bushing. Some people stop the whole subframe and use the opportunity to also replace the bushings that mount the whole rear cradle to the chassis. For this job, we are leaving the subframe in place. There are several methods to remove the large factory bushing. What we chose to do is use is a traditional removal tool to push the bushing out. Others choose to drill through the factory rubber, then saw several slits through the casing to collapse the bushing. Both methods work, just depends on your preference and tool collection.

Removal Kit:

The removal kit works like a plunger. You have a “pushing end” and a receiver. A bolt rides through the center and is secured with a nut at the other end. As you tighten the assembly, the stock bushing is pushed through its residence until it “falls” into the receptacle. Going slowly is key as is generous amounts of PB Blast. You must ensure torque is applied evenly to avoid doing any damage.

Stock bushing removed with the help of a bushing removal tool:

Daylight!

With the factory bushing removed its time to install the new one. We chose the SPL solid aluminum bushing to match the ones previously installed at the front. This is a solid chunk of billet goodness, and provides the strongest possible mount with maximum stiffness. Whiteline and Energy make urethane versions as well. If you go the solid route, a word of advise. A day before you tackle the install, put the factory bushings in the freezer. This will contract then ever so slightly, but will allow them to slide more easily into place. Leave them in the freezer till its time to install them.

To install the new bushing we used a simple mallet and tapped it in place. It’s actually quite easy.

New bushing installed:

From there it’s a reversal of the previous pumpkin removal procedure. Make sure you get the pumpkin all the way squared up to the subframe otherwise you will never get those 2 front mounting bolts back in place. We found that by installing the rear bushing nut and tightening first, it “pulled” the pumpkin more into place allowing the front bolts to more easily thread in.

Bolt the driveshaft up, then output shafts and you’re done! Torque specs can be found in this diagram:

The results? Awesome! You will LOVE this mod. Even though the front bushings have been installed for several years the rear is the most transformative. The car bites down much harder now from a dig as well as in the turns. We noticed a slight increase in noise due to the fully solid mounts but its so faint it’s not even worth mentioning. Launch the car and that “hop-hop-hop-hook” sensation you used to feel is now just a squat and hook. Your axles will thank you……

With the affordability of these bushings, it’s on that list of “must have mods” for this car.

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SPL Compression Rod Bushings

These just arrived from SPL today for both my car and Kwame’s. Can’t wait to put them in. Kwame’s car is still on his original set, but my car is already on the second set. The first set was trashed about 2 years ago, and I replaced both sides. Unfortunately Nissan doesn’t sell just the bushings alone, you have to replace the complete arm. SPL thoughtfully released these bushings recently, and we’re eager to try them out ourselves. You can see where they install in the 3rd pic.

Click Here to order yours!

Deconstructionism

So Kwame got off his lazy ass today and dropped his damaged, stock subframe. A brief encounter with a guardrail in the rain left this one with a fracture. Next up, swap the new one in, complete with the Whiteline and SPL bushings, as well as convert all the remaining rear rubber bushings to the Whiteline urethane ones as well. Rome wasn’t built in a day, this car sure as hell won’t be either (in fact it’s been exactly 1468 days since the car has been driven!)….but it will be worth it when it’s all done. There won’t be another Z33 out there as well balanced as this.

Prognosis Negative (Camber)

One of our good customers out west just forwarded me some pics of his latest setup. Steve’s been a good customer for awhile now, and this past winter, we set him up with a bunch of new stuff. First was a deal on a set of AME Circlar Spec R’s in blue (19×9.5 +15, 19×10.5 +15). Then just after the new year, we sent out a new box of goodies, including SPL Front Adjustable A Arms, Eibach Rear Camber/Toe Kit, Powergrid Front/Rear Endlinks and 15mm Project Kics Spacers. The car is lowered on Zeal Function Xs Coilovers. The Ings hoods are just dead sexy on the Z’s too.

The camber? Yeah, there’s alot. Not quite sure exactly how much just yet, since this was the trial run, but it’s a work in progress. As Steve put it “As for the camber, unfortunately, running an aggressive stance is a trial and error type of deal. This is my first attempt at it, so I had to make it fit with tires that are too wide. I’ll probably go with something like 245s or 255s in the rear next time (prob in 2 weeks when these wear out ), which will allow me to dial out some of that neg camber. As it is, I had to raise the car a full inch in the rear, and roll the s*** out of my fenders just to get the car to move!”

Stay tuned here for the final pics once everything is fully setup!

Mods Ahead

Organized the new round of bushings going into my car shortly

SPL solid rear differential bushings front/rear
NISMO rear upper control arm bushings
NISMO rear lower link bushing (aka spring bucket – inner)
NISMO Exhaust hangers
Whiteline urethane subframe bushings (traction kit)

Will be doing all this in conjunction with the 4.3/Quaife pumpkin – I hope to have it done in the next few weeks.

Right now, just waiting on my cluster to come back from Racepak with the latest firmware update (odometer…nice!). Will also be getting the USM module so I can integrate the fuel level sensor. Also picking up an oil temp sensor as well.

Pressin’ On

The press has seem some heavy action here lately – just swapping out stuff on our own cars! Kwame has a full array of bushings he still needs to do. In preparation for installation of my 4.3 final drive equipped pumpkin, we had to press out the stock pieces from the pumpkin. I picked this pumpkin up last year from a customer who had it sitting around. It had an inordinate amount of rust on it, and it made removing the bushings a royal PIA. Not to mention, when you’re trying to secure a ~100 lb pumpkin in a press, it’s no easy task. One bushing dropped out easily, but the second one just wouldn’t budge. Finally, after some coaxing with some Nuts Off (a really good penetrating oil), the air hammer and a cutting wheel, we managed to force it out. Next up we’ll file off the rest of the surface rust, and install the SPL Solid Bushings in their place. I think I’ve also been talked in to just dropping the subframe and doing the Whiteline Rear Traction Kit along with the rest of the NISMO bushings for the rear, as well as the NISMO exhaust hangers, to compliment the rest of the NISMO bushings already on the car. It never seems to end……

New SPL rear toe arms for 350Z/G35 and 370Z/G37

SPL pro rear toe arms replace the stock mid link to provide toe adjustment, for those who have converted to true coilovers in the rear suspension and who no longer need the midlink to hold the rear springs.

Combined with our rear camber arms, this arm will allow for a wide range of adjustment for rear toe and camber. Features 1.25″ 4130 chromoly (which has a higher strength/weight ratio than aluminum!) tubing construction for
strength, and QA1 Endura 2000 series chromoly rod ends with QA1’s unique maintenance-free injection molded teflon/kevlar lining for long operating life and precise handling.

Adjustment specs

Toe adjustment range is +/- 6deg (+/- 7deg w/ stock eccentric bolt) from stock arm (note: toe adjustment affects camber)

Retail price: $299

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

(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

New Spherical Control Arm Bushings for 350Z

New from SPL comes these spherical front lower control arm bushings for the 350Z. The inner bushings in particular have proven problematic for the Z33 chassis. On my own car, we found they were torn, which caused some very slight clunking up front and vague steering response. It had been that way for so long, I almost began to think that was just how it was. With the car up in the air when we did the last cornerbalance/alignment, we found they were totally shot! We’ve had many customers report similar issues as well, with mileage ranging from only 7500, to upwards of 90k +, so it’s going to be just one of those things on this car.

SPL’s new solution is a solid spherical bushing to replace the factory soft rubber units. These are made up of QA1 slot-loaded bearings that feature a unique slot-loaded injection molded kevlar liner that cannot “pound out” when dirt gets on the bearing ball, providing a self cleaning and self lubricating bearing that is suitable for street use. Large 3/4″ size bearing offers huge load capacity and long life. Highly precise (machined to 1/1000th inch) CNC machined 6061 aluminum bearing shell and sleeves provide excellent fit and finish.

Priced at $149 per set of inners or outers, or $298 for all of them. Order off the website (just click the picture above) and get free shipping in the 48 states. If you need a combo deal with any of SPL’s other items (or any items in general), just let us know!

Adam’s Project Z33: More Stuff!

Before……

Before….

After!

After!!!!

No major news, but forward motion never-the-less. Picked up my fuel rails last night from the guys at Action Powdercoating. Vinny and the guys there are the best around – fast turnaround time, great prices, and they’ve been doing this for years. Had them done in a nice satin black, which hopefully will render them as close to invisible as possible once everything is installed

Also got a shipment of in SPL Differential Mount Bushings. We’re now a dealer for all their parts so if you need anything, just hit us up!

While I don’t have the 4.3 pumpkin back just yet, progress is being made on it. All sorts of custom ‘ish needs to be done to get that workable. I leaped before I looked on that one. Sleeves are being fabbed next week I was told for the pinion. Not sure what all else is involved to be honest….I’m sure it could be it’s own blog lol.

The plenum is still up with the engine guru. I’m going to check up on that tomorrow and see if he found anything interesting. I have picked out a throttle body now just have to acquire it and send it up to have an adapter plate made up so I don’t have to hack up the Cosworth.

Dave – you’re not reading this, but answer my text….I needs a cluster ! Seriously, I can’t wait to see what he works up for that thing – I think I’m looking forward to that part more than anything else at this point!