Project 635 - 300HP RWD 620

[bertvorgon]

Yes..clutch. Over the years, as I nailed my suspension down, I got rid of any understeer tendency at lower speeds for Solo..lots of castor and some camber, so turn in is awesome and the foot does the rest on the throttle. Maybe my driving style, but I never had that type of issue.

I have always said I can steer my car with the throttle. I have a very firm understanding of weight transfer, how and when to use it, and the "traction circle".

I hope the throttle control works. I drove my car to the race track today and there were a couple of times, in slow speed traffic..the throttle was like an off and on switch.

My car is at it's best in very fast canyon carving, RPM is up and small throttle hickups are not an issue.

[DADZSUN]

Since the last update, 635 sat in the garage. It was extremely frustrating because for 3 summers now I swore I'd have a toy to drive around and this summer was looking to be yet another disappointment. Ultimately, I purchased a sweet 2003 350z track named "Dez" for peanuts and it did a great job biding my time while 635 got sorted out. Driving this car I realised how much I missed my old Brickyard 350z. This chassis REALLY suits what want in a RWD grand touring platform. This will be my DD going forward.

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Back in end of June I came to realise that the 635 'hacked' ECU was getting too difficult to drive around. I shipped the ECU and a spare to the vendor in Tampa, and then began 2.5 months of a total shit-show. It's shocking to see the WORK a customer has to do to get service in this day and age. Since this was 'free' I bit my tongue and waited through plethora of excuses: sickness/vacations/engagement etc to get my ECU back. The vendor confirmed the ECU I sent was faulty with a high idle on their Z33 test mule. My backup ECU was reprogrammed along with my tune and (eventually) shipped back.

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Good news? It's better. Bad news, idle is still high and sometimes locks on an RPM (cruise control anyone?). After playing around I'm starting to suspect the 'hacked' OEM wring harness provided by the same vendor. I'll be able to confirm 100% when I swap the 635 ECU into Dez and if it behaves, then it's the harness and I'll order a Wiring Specialties VQ35DE universal replacement. I just installed one of their harnesses into a customer's 510 and was REALLY impressed with the quality.

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In the meantime, with the DBW connector jimmied 635 is driveable and I've wasted no time putting it to use. I'm determined the 'knocking/rubbing noise is the 370z axles I installed. They apparently work on Z33 and therefore should work on mine. After further research I realised that the 370Z axles are approx 3/4-1" longer and while Z33 can handle it, I purposely DECREASED 635 rear track width to tuck the wheels under the flares. Wth this decreased track width, the marginally wider 370Z axles are bottoming out. This was evident not only when cornering, but even when hauling stuff.

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I've since ordered 350Z replacement axles/wheel bearings, and will save these new 370Z axles/wheelbearings for Dez. That's about the last of the short term plans for 635. I've got a customer 510 to finish and my personal 510 needs the KA24e sorted out once and for all (solid lifters is my next plan). Once those are out of the way, Phase II for 635 will be to shorten it's wheelbase 9-10", install remote powered brakes, Quaife LSD, new wiring harness (and potential ECU), and the steering potentially redesign (I'll save that detail for a future posting).

For those wondering, since Dez and 635 are essentially the same underneath, what's the difference? 635 is MASSIVELY quicker, which is shocking because ODB2 apps are still showing only 83% throttle opening. I'm guessing the tune and -500lbs is helping here. Dez's Brembos are MUCH stronger and steering input is a lot sharper. Ultimately, 635 is a hell of a lot more fun to drive, Dez is far more sophisticated.

[bertvorgon]

As a "platform', the 350 and my G35 share the same bits. Last summer, lets just say I got to press my G35 at
full combat mode, against a Specialty built, 200+ Hp Datsun 510, in the hands of a very good driver.
We were neck and neck through the corners and in an uphill, long drag, EQUAL.

These cars IMHO are at their best, NOT slogging through traffic, but out on the open road. Nissan put a ton of castor into these things, which induces some serious negative camber, so the bite on corner entry is JUST LIKE MY 510. Many, many years ago, I raced a G35 on an un-named hwy, obviously driven by someone who had serious driving experience, that so impressed me with the handling, that I bought mine when the time came to replace my Toyota GTS. The steering is incredibly precise, requiring very small hand movements on the steering wheel. With a good understanding of weight transfer and how to use it, these cars are pretty spectacular in the handling dept.

[ostaylor]

Frustrating for sure on the delays but good to see you continuing to work through the issues and awesome that you found a DD that you are enjoying.

I'm pleased that you like the Wiring Specialties harness... I just dropped a lot of $$ for their SR20DET harness, Link ECU etc for my build and I'm patiently / impatiently waiting for them to build and ship it.

[DADZSUN]

Project 635 continues to progress - more so with my last customer commitment rolling out a month ago. For the first time in almost 5 years I'm free to work exclusively on my own builds.

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One of my first goals was to try out a taller rear drive. The stock RWD 3.54 350Z diff is a little too short for my liking - esp with the truck 1" diameter smaller wheels compared to the Z33. First gear is pretty much useless at full throttle, and even getting going for that manner (hardly through an intersection before having to shift). So I chased down a rare 2002 Infiniti Q45 2.76 R200 in Queens NY for only $150 USD, bonus was that it was only 15 minutes from where I was staying.

Wow, did that diff ever calm things down! I was given effectively 20% taller ratios and that made 1st gear useable, and cruising at 120kph dropped from 2800RPM down to 2250 RPM. Yes, I lost a bit of pep in the taller gears, but 1-2 are now actually usable w/o excessive wheelspin...

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Well, there still is lots of wheelspin. But that's where this Quaife comes in! The 2.76 is an open auto diff, so I ordered the appropriate Quaife helical bolt-in (no stub swaps required). I've got a complete set of new R200 bearings and seals waiting for me and I should have this all done mid-winter.

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In the meantime, I'm still able to cruise and enjoy the 2.76. The hacked ECU still idles at 1500 RPM (only on first start-up, subsequent start with the engine warm gives me more like 3000-3500 RPM. And so that's where this comes in!

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Taking advantage of the Black Friday sales, I was able to grab this PnP unit, CANBUS WideBand 4.9 controller, fuel pressure sensor, and intake air temp sensor for $3K CAD total. Add the excellent support from the folks at Openheim Engineering who uploaded a base map and will provide remote tuning, and I should be all set by spring. This ECU will also add theft deterent, traction control, on-board data logging, accelerometer, etc....

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While waiting for the ECU to arrive, I've installed the original set of RX-7 FD wheels and Micheline AS4 225/50/R16 tires. My goal is to drive this truck for 3 seasons, but still take it out in the winter whenever the roads are dry and > -5C. These tires should make it feasible, and certainly held well when trying some drifting in a local parking lot.

You'll also notice the bed rack I've made along with the roof top tent. This Datsun will be doing quite a few biking road trips this coming season and so I've been testing setups etc. I'll have a dedicated post on that down the road.

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With that extra weight in the back, I decided to install some Air Lift airbags. It took some modification to make it ft the OEM divorced rear G35 suspension, but test ride showed I'm onto something good. With 10psi the truck stay ed level, the extra 250lbs in the bed kept the rear planted and smooth riding.

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Once the ECU is done (mid-Jan?), the remote-boosted brakes are done, and the steering tightened up, I hope to chop 10" out of the wheelbase. Not only will it aesthetically look better, but the truck will be more nimble. Ride might deteriorate a bit, but it's a Datsun with modern multilink suspension, it's waaayyyyy better than OEM ever was.