Project-Zero: Wheel & TireFitment

NOTICE: The information on this page is expressly for my particular GBS Zero Roadster build.  My car has a fairly wonky staggered setup with 15x7 (4x100 pattern) fronts and 15x8 (4x108 pattern) rears. 

Car Mechanicals 

• Front: Mazda, Miata ( 1999 - 2004 )
• Stud Pattern: 4x100mm
• Center bore: 54.1mm

• Rear: Ford, Sierra (1982 - 1993)
• Stud Pattern: 4x108mm
• Center bore: 64.1

Current Fitment: Team Dynamics ProRace 1.2

• Front
• Size: 15x7
• Pattern 4x100
• Center Bore: 57.1mm
• Offset: ET -15
• Tire: Toyo Proxes R1R
• 195/50R15
• Rear
• Size: 15x8
• Pattern: 4x108
• Center Bore: 73.1mm
• Offset: ET -27
• Tires: Toyo Proxes R1R
• 205/50R15

• Required Center Rings
• Front: 54.1(ID) to 57.1(OD)
• Rear: 64.1 (ID) to 73.1(OD)

Resources

Good video explaining how to measure offset.

Project-Zero: Swirl pot mounting and mods.

I have two concerns informing my swirl pot mount:

• Ensure clearance between the steering column and fuel return hose.
• Ensure clearance on the bulkhead to mount high-pressure fuel pumps.

I knocked this together with a sheet of 4"x10" 14ga aluminum. Not necessarily ideal for every build but workable for mine. A minor, pretty straight forward modification of the swirl pot was base is necessary

Project-Zero: Rear Brakes, first fitment notes.

I’ve been looking over Richard’s build log for some information on mounting the Sierra brake calipers, having one of those moments where I can only think, man, that just can’t be right? Specifically swapping the calipers left for right. I’m not saying that it isn’t the way GBS intend them to be mounted, just that it's weird because it would make servicing the rear brakes kind of a pain.  Having to dismount the rear calipers to bleed them is super sub-optimal.

UPDATE: 

After a little experimentation I've confirmed that you can't route the parking brake cables to the calipers if they're on the "correct" sides of the car. Disappointing but whatever...Might be a reason to upgrade to different calipers later.

NOTES:

• Caliper brackets bolt to the uprights with M10x1.5 50mm bolts.
• Parking brake cables are 10mm (3/8") diameter, good to know for replacing the p-clamps.

Project-Zero: Rear end test fitments.

Decided t throw the differential and drive shafts into the car.  They’re needed to be able to install the rear brake hubs, rotors and brakes.

• Off-the-shelf spacers suck - The spacers I bought from McMaster-Carr (M12x15mm) are just a bit too long. They bind up when attempting to install the differential.  I had been packing out the space with M12 washers. I was stupid and should have just bought a 2ft section of  1” OD .25” wall aluminum tube and ripped it down to size with the bandsaw.
• Hub orientation - The hubs carriers have a flat spot on along one edge.  They should go toward the back of the car.
• The axels are handed - The longer of the two axels goes on the passenger side of the car.  The axel nuts are left hand thread on the left side of the car and right hand thread on the right side of the car.
• I need to clean the internal splines on the hub - They’re rough and do not slide nicely onto the axel splines.  I should scrub them out with some soft of steel/brass brush to clean up any surface rust and shit.
• Once installed, the hubs and axels will install and remove as one piece, until then...it’s going to be a shit show.
• The axel nuts require a 41mm Socket - I have ordered a 41mm deep impact socket. A1-5/8" socket would also work.
• Once the hubs go on, they're staying on - Because the GBS kit does not use stub-axles once the hubs are on, removing the axle shafts becomes a HUGE pain directly in the ass for serviceability.

Project-Zero: Right rear upper control arm.

It’s only been a FUCKING MONTH since I found out that the right, rear upper control arm on my GBS Zero kit was in no way going to line up and go into it’s home...but it’s on the goddamn car now an barring something really fucky happening it’s not going to have to come off ever again.

It took most of the day to wrestle it onto the car, including a protracted run to the hardware store to pickup up some new, shorter M10x1.50x60 bolts for the upper and lower shock bolts. (For both sides of the car.) The hardware that GBS ships with their ATR shocks is M10.x1.50x70...and those are too long. On the upper mounts they interfere with the frame so you’re not actually able to tight them down snugly.  On the bottom mounts the excessive length isn’t such a problem but since I’m replacing some I might as well replace them all.

My only significant frustrations in this build [so far] have been the horrible quality of the front brake tube nuts and working with GBS to sort out the rear control arm issue. Getting GBS on the phone to talk through the issue was practically impossible. Ultimately the issue was sorted out in a few quick emails but my experience has been that it is almost impossible to get phone support from GBS. (From the US, at least.) I’m honestly deeply disappointed that it took nearly a month to get the control arm issue sorted out. It put a damper on my build enthusiasm with back-of-my head concern that potentially the frame might have had issues.

Project-Zero: Low Pressure Fuel System Plumbing

Started Plumbing the low pressure fuel system.

The feed fuel feel and return lines are 5/16” OD nylon tube in red and black. (red=feed, black=return.) These run from the low pressure filter and pump at the rear of the chassis through the tunnel to swirl pot at the front of the car.  The tunnel has some brackets to help route them cleanly.

The tunnel brackets need to be fitted with grommets to the fuel hoses from rubbing  through. I bought out all of the [5/16”ID, 716” groove diameter, 1/16” groove depth] grommets at my local Outdoor Supply Hardware. These fit into the brackets perfectly and offered a VERY snug fit for the nylon lines.  So snug that nylon fuel lines tended to pull the grommets out of their home while drawing them through.

To solve this, I squeezed a nickel-sized gob of white grease onto a paper towel, then drew the full length of each tube through the greasy towel. I then wiped each tube down again with a clean, dry paper towel.  This left the nylon fuel hoses clean and just slick enough to thread through the tight rubber grommets without pulling out of the chassis in the process.

Project-Zero: September Parts Drop

The only parts I planned to order this month have arrived.

• Radium Engineering Ecoboost PCV kit
• ARP flywheel bolts
• ARP pressure plate bolts
• Flyin' Miata clutch/pressure plate kit.

Of note, the Radium Engineering PCV kit is maybe a little unnecessary and overkill. The GBS comes with a PCV blanking plate for the Duratec/MZR engine that I've optioned for my car, it could be modified to suit.