Turning 626 GT into an AWD

[FE3-323]

rusty. would be an understatement my friend

[STW]

I guess it would be more accurate to say there's a bit of metallic iron in that heap of rust... Anyway, here are the promised comparison shots, with a small bonus.



The AWD on the left, FWD on the right. It's obvious the structures are similar, but not quite identical. The rear transmission mount is further back in the AWD version, and the rails make a much more pronounced kink at the front. Also the left rail on AWD makes a noticeable curve outwards for transmission clearance.



These photos illustrate the difference with the structural height of the subframes. The deeper curve in the AWD subframe is compensated by higher A-arm mount points; the suspension geometry is identical with FWD. It's obvious when comparing the A-arms; in FWD the arms are practically flush with the subframe where AWD has a very prominent gap. The deeper subframe is most likely to give more firewall clearance without redesign.

Ultimately, the proof of the pudding, as they say, is in eating it. So here's a test fit of the AWD subframe on the FWD body:



Fits like a glove... If not for the unused stud in the right side, you could not tell the subframe is from a fundamentally different kind of car! There are times to be grateful for afterthought versions, I think



Finally, since the shifter is built on AT shifter dimensions, the entire shifter assembly (including the cables) also fit the FWD as if made for it. However, since I'm going to replace the floor, the shifter fitment is kind of a moot point. The cable grommet fit is a very nice bonus though!

In all, the positive surprises in the build have been few and far apart, but this time I can't imagine having it any better. Both subframes are in excellent condition, and AWD one requires absolutely no modifications to fit :jump:

[FE3-323]

excellent pictures to show the comparison!!

[STW]

(Apologies, this post should have photos but they turned out all wonky. I'll add them when I get good photos)

Okay, here's a short break from the decay and devastation!

What and why
I bought a set of Silvia 3-projector headlights to upgrade the 626 light output. Common for the designs of the late eighties, the GD never received praise for it's headlights, and now HID projectors setting the bar their shortcomings are more obvious than ever. Given that in winter time we get light for far less than a third of the 24h day, good headlights are very important for visibility and fighting driver fatigue.

Silvia projectors are of course old and halogen based; they won't turn into modern headlights by tossing in HID conversion bulbs. Optics quality and light distrubution differences in the bulbs would make sure the light output would stay far below modern standards. However, the enclosure offers a good platform for HID projector retrofit. A modern enclosure would look out of place in an eighties car; Silvia headlights instead have common design language with Mazda.

Legal schmegal
One great problem with the mod is the legislation. Since fixed headlight Silvias were never made for Europe (or anywhere else for that matter), there are no E-marked headlights, and also the light pattern is wrong. Earlier it would've meant automatic disqualification at vehicle inspection, but since then the rules have slightly laxed, with projectors it's usually enough if the projectors are ECE-approved and the glass is approved wherever.

First impressions
The shape of a Silvia headlight is familiar; slim and long trapezoid with rearward slope and lower corners pointing inwards. At a passing glance the lights appear almost identical, but the looks are deceiving; upon closer inspection, differences become obvious. Even though the plastic housing is about the same size in both, the glass in Silvia headlight tapers considerably. On side-by-side comparison, the silvia headligh is slimmer and narrower (and much more so with the wide euro headlight). Also the glass is much steeper, almost vertical. Mazda glass on the other hand is flatter, Silvia is more convex. The steeper headlight angle adds an interesting feature on the fascia; it gives a similar stepped grille appearance as certain Hondas and early Lancer Evos. Carefully planned chamfers and fillets to fill the gaps between the bumper and headlights could actually subtly modernize the look, without deviating from the original style too much.

Differences mounting
Mazda headlight is attached to the car by four axial fasteners and two extra braces. The silvia unit has two axial bolt holes in the inner and two radial on the outer edge. This means unlike the euro headlight, the Silvia one is probably impossible to line up with hood edges, and given how much narrower the S13 light is, it's not even desirable. Fabricating mounting adapters is, all things considered, a pretty trivial task.

Cutting Corners
With the Silvia headlight geometry and mounting envelope differences known, it's obvious there is no way the Mazda corners are going to fit the Silvia headlights. There is a slim chance the US style corner light wraps far enough front to cover the side mounting studs without too much of a gap, but it's impossible with the euro corners which mount flush on the headlight chamber wall. However, deciding to go Silvia corners is jumping to conclusions. There is a third option, more of it next.


...nope!
Headlight layout
The original light setup is, from center outwards, an H3C fog light, a single H3 high beam and a single H1 low beam. Regular driving lights will be replaced by ECE approved HID units for performance and legal issues with bi-xenon projector providing low beam and dual high beam, but fogs will be gone for good. For best performance, fogs should be placed low and wide apart. It also makes certain feature much more useful; connecting fogs independently to the direction indicator switch they become nice cornering lights. Some cars, like most new Peugeots, offer such functionality as a factory feature. I originally planned to use LED DRL's in their place, but I found out there weren't small enough DRL's to fit. Upon realization the corners were going to cause a lot of grief and remembering Mazda6 headlight layout I had a smalltime epiphany; I'm going to use the vacant spot for a Hella 55mm front turn indicator. Corner lights are thus no longer required, and they can be made purely decorative without approval requirements. It allows nicer finish without the legal and technical hassles involved in modifying live units.

Putting it all together
I bought the headlights to better know how I should proceed once I get to building the front end. Right now my #1 priority is to get the body rolling; I've set myself the goal of having the car on it's wheels by the end of the year. I'm not hurrying with the updates on this part of the project, until it's actually time to start building the front end.

I did a sketch of how the front end might look like after the modification; the style is based on KüWe bodykit which I like very much.


It's a very rough sketch, but at least for me it's a guideline on how to plan ahead with the modifications. I'm not absolutely convinced I'm doing a favor to the looks of the car, but as long as it doesn't look like a hack job and gives 3000 lumens at 4300K, I'm happy.

[bogaut]

always loved the silvia headlights, good luck on the retrofit. projectors are an awesome upgrade compared to old style reflectors

[STW]

Thanks! Where I need luck the most is with the inspection officer, everything else is just a matter of effort

Updated the post with some pictures too! More will come within the next few days.


Also, I received the trailing arms for the AWD! Here's a shot of AWR made FWD tubular trailing arm and their custom AWD trailing arm. It was incredible how they simply agreed to make a set with little extra cost! They deserve respect.


Top one is FWD, bottom AWD. The hand brake cable bracket attachment point location caused some confusion first, but it was cleared fast. The mounting points on the chassis are the same in FWD and AWD, the knuckle is different; thus the length difference.

I think I'll paint it semigloss black to reduce undue attention.

[FE3-323]

nice to see a set of trailing arms whipped up for the project! how much longer exactly are the AWD ones?

[STW]

I can't remember exactly, I think it was 30mm. The throw reduction for the longer arm is really insignificant, I wonder if they did it for more clearance around the CV joint.

I'm going to need some new bushings soon! The stock bushings aren't too bad, but the constant desire to always make things a bit more extreme isn't letting me off easy here either. The problem with bushing is the harder they come, the more they bind causing unneccessary harshness that won't improve handling but increase fatigue, both the driver and the car parts. The ultimate solution would be spherical bearings, but those are usually forbidden in street use. Then again there's a lot of room inside the bushing barrel. How hard would it be to machine an adapter sleeve that fits inside the barrel and accepts a spherical bearing. Rubber caps would finish the look and act as a weather seal. Hmmm.....

[FE3-323]

many people in track use have snuck by with spherical bushings molested to look like OEM/and or rubber pieces.
get it on the road. then change them to sphericals.

[STW]

It needs to be stealth from the get-go. We have yearly inspections (with the exception of new registrations which get a three-year grace period)... it sucks but there you have it. On the other hand you've seen in what kind of condition a car can get here in under 25 years so it's not all just bureaucratic bullying.

[STW]

I may have found a perfect solution (don't know yet, hopeful!) for the corner indicators. Japanese U12 Bluebird has exactly the same corner indicators as Silvia, but around here they seem to be much more subtle, similar to J30 Maxima, and resembling closely the original 626 light. In any case, U12 corners are very cheap, available, and E-legal! I just need to check if they really do match the silvia headlights, and that's one big problem less if they do!


A NZ J30 corner

[STW]

Those Bluebird corners turned out to be twice the size of the original Mazda corners. Never go with the initial appearance... I guess I'll be going for Silvia corners then.


Not having a steady job is a terrible thing for the build, can't keep up with the pace I once did. However, here's the latest on the headlights.

I'm really happy I decided to go with aftermarket projectors. The original reflectors are cloudy with milky white areas, either age or way overpowered bulbs. Here's a shot of the low-beam reflector:



The white area below the bulb hole is not a camera bloom; it's really that clouded. The rough areas at the sides are complete mystery to me; perhaps someone thought a crisp cutoff wasn't the best idea afterall. Anyway I'm really happy I decided to check. These projectors are little more than garbage.

Morimoto projectors are designed to fit H4 and H7 bulb holders, but unfortunately since the Silvia projectors have H1s, I couldn't just bolt the set in, and the high beam projectors needed brackets anyway. So I engineered a set and had them made by a laser cutting company. Here's the shots:



The four-pronged thread inserts have about the same amount of play they had in the original brackets, so I think they should work well without binding. I'm going to fasten the ball socket in place with butyl adhesive, the same stuff the glass cover is glued with. Not fancy, but it works. The third bracket design in the photos are for turn signals. I'm not going to house the foglights in the headlight enclosure (non-optimal placement) and all the available DRL's were at least 90mm in diameter, so those didn't fit either. Thus, a turn indicator it is. I've also noticed it can be terribly difficult to see a corner indicators in a roundabout, so consider it a benefit for the fellow driver.

[STW]

Okay, a MAJOR snag. I mean a really huge one. The talks for exemption permit were close to being okayed, and then this asshole official decided that because I'm altering the drive train, no big engine changes can be allowed. Why? No why. They do it because they can and because they get no other joy from their work. *Especially* all forms of supercharging were no-go. No real explanation, just a vague "too great power potential". Given that the legal limit for power increase on the street already is 20% over highest rated factory engine, the restriction is simply unreasonable and petty. Ah well. If the turbo plan falls through, I could just build it with the naturally asphyxiated FE DOHC at first and then start the turbo battle later.

[FE3-323]

mega ****ty sorry for the bad luck. Personally. id do it anyway

[jay]

"Given that the legal limit for power increase on the street already is 20% over highest rated factory engine"

jeebus that right there SUCKS right there. I just bet the car makers and legislators would love to shove this down our throats here.