POS13 - A Nostalgic RallyCross Project

Ok, so update time.

Definitely NOT a Project Car miata has been stealing some time and energy lately to get sorted

But with only two RallyCross weekends left in the schedule, and me missing all of them so far, I decided to throw some time into the POS13.  About this time, work decided that a 10 day weekend would be fun, apparently contracts are Hard?  So I had some very dedicated time this week to dive into the rear suspension!

Step 1: Wash it like some lost stray puppy

Then, as luck would have it, someone in a couple towns over was parting a S13 hatch, and had the actual hatchback for sale!   I needed to replace the rotten hatch hinges so I went through all the pain and suffering of using Facespacemarketplacespace.  Sure enough, it had been sold, but he had a 'rusty' one that had good hinges available for pocket change!

It suffered from SE disease, where 90's Nissan in their infinite wisdom decided to fit a foam spoiler to the hatch top.  This open cell foam over time leached in water, held it against the metal, and rusted out every single top spec S13 ever made.  However, the glass and hinges were in pretty nice shape, not a bad score for my purposes!

Since rust is what got me here in the first place, I decided to try a rust remover.  I'm always hesitant to use anything so universally pimped in 'social' circles, but Evaporust really worked well and didn't need much cleanup, and after a quick rinse, the new hinges came out perfectly rust free!

I prepped everything involved with this interface with epoxy paint and primer, gave a faying and fillet seal of RTV, and greased the hinges well.  Then assembled the hinges in place and only tried to crush my hand once!

Success, it's now a sealed roadworthy car!  The first task, taking some used oil back to the FLAPS

I was immediately reminded of why I decided to park this car up.  Every corner it tried to oversteer and kill me!

Ok, so with some time to dedicate I dove into the rear end of the car

Step 1:  Surely the rear toe is Berk'd?  backed the car into the garage, and the most obvious 'fix' is that the hammering of the suspension at events resulted in like 47" of toe out, right?

Nope, slapped some toe plates and it was dead nuts even, 0" of toe, perfect.

Step 2: Well crap, what's next?  Certainly the struts are blown, bent, and otherwise given up the ghost of suspension control.

There's a ton of wear on the spring perches showing binding, so when I pull these apart, I'm sure they'll puke and die.

No such luck, they're filthy, but cleaned right up, and perfectly returned and damped just as the new in box ones.... So I kept those just that, new and in the box, and looked at other parts of the rear setup.

Step 3: The top hats involved stock top hats, an off the shelf spring perch, and a handful of odds and ends washers and rubber bushings thrown at it. 

This seemed to be the only culprit for the wear on the threaded spring perches. But nothing seemed overly bent, abused, or different from stock.  However, I'm pushing the limits of suspension travel and abusing it way more than stock.

I took a bunch of random measurements and determined that the front top hats I ordered from Wales with the front suspension might have enough extra meat on it to work if I cut them down:
 

Then down that path, I quickly realized that the thickness of the center area with the bearing was 20mm too big for the hole in the car.... and if was going to open up that hole, things would just have to get crazy and extended shock towers... then I'd need a cage to tie it all into, then I'd be way past what I wanted the POS13 to become... so bail, bail, bail.

Step 4: With no obvious smoking guns, Well that escalated quickly...

So in some of my research, what has made the S13 240sx a great 'drift' car is the built in anti-squat geometry, it almost instantly creates oversteer when power is put to the rear end.  This created a legend in the S13 and 180SX, but in the S14 and S15 chassis, they dialed out this anti-squat geometry of the lower control arm, and with the love of the aftermarket, GKTech makes a relocation brackets that put the lower control arm in the spot of the S14/S15.... and while I'm in there, they also make a weld-in subframe support bracket kit.  So might as well pull the subframe to update to the latest specs:

In reply to rallyxPOS13 : I am glad to see you back at it. My rear subframe mods/ reinforcement was a very enjoyable part of my project. I was also able to brace the brackets that the upper forward links attach to with 1" tubing that still cleared the body. I don't know if that is legal in your situation or how much it is really needed, but it doesn't add much weight.  

 A couple pictures of the reinforcement tubes

Oh wow, that does look like it'll shore it up well!

Have you tried to remove the diff with that support in there?  I've often had to push the axle upwards to pop the inboard CV off the diff to remove the diff without removing the axle from the hub.

Making small progress throughout the break. 

As I saw some welding in the future, I checked the welder out. Of course the bottle was completely dry, and not only that, but the welding wire was gone!   I found my backup spool of .030 wire, but for some reason I'd bought coated flux core instead of copper 

I'm pretty sure everyone picks up pressurized gas cylinder this way, right? 

No asphyxiation for me! 

When I got back home I rolled the subframe outside to powerwash the accumulated dirt off, to prep it for work:

In the background is the mulch from the group of 4 trees that killed my house, die Tulip Poplars, die!

When removing the diff, it was obvious that the subframe bushings had truly died, so I hopped on the interwebs, and ordered a replacement set from Z1 motorsports.... this represents the biggest risk to completing the car by the doubleheader rallyX, getting folks to ship things around a holiday weekend.  I'm doubtful.

First thing was to replace the dead bushing in the rear lower control arms with the spherical bushings that I got from GKTech, it allows more movement with the stock arm, and can (hopefully) accommodate the offset fwd LCA for 0 anti-squat.   I have a HF press, I own various ball joint tools, but even with that whole repertoire, there was no good way to remove the old bushings by pressing them out. I had to resort to fire...

I've found over the years of doing things the 'wrong' way that driling a few holes around the perimeter helps airflow for the flames to work quickly in the bushing:

After fire kills all the rubber, I just hit this with a sawzall to cut the busing sleeve out, and then drive it out with a chisel.

Since I was pissing off the neighborhood anyway, decided to apply fire to the subframe bushings too:

I would normally feel bad, but with prevailing wind, it was headed to my neighbors who were driving 4-wheelers around, shouting at their Berk Trophies, and blaring Pop-Rural music, so enjoy the smell, shiny happy people. 

Back in the garage, I was able to press back in the sphericals just fine, but it took some time:

With those in place, I went ahead and installed the anti-squat 'fix', and you can see that the front attachment (subframe is upside down) is lowered, (picture top is the new location, bottom is old):

To better describe this, here's Lt Dan: 

For tonight, I wrapped up the LCA mounts with adding a support of the aft location: 

Nice progress! Funny how the smell of burning bushings is not nearly as bad when it speeds up the process, hope your neighbors enjoyed it... In answer to your question, I have not removed the diff with the braces in place however there is a reasonable amount of room between the axle shaft and the brace tube, so I would not expect a problem.

Got some more welding cranked out yesterday.  Some of it was actually halfway decent, some of it was Ok, some of it was instantly ground right back off and tried again.

Gave it a lick of paint to cover up the dirt, rust, spiderwebs, and mediocre welding

Here's to hoping the old control arms still fit after I'm all done!

Oh, even had some time left over to beer-can smoke roast some chicken while the paint dried:

Ok, so now those of you following along, watching me mess around with the minutiae of a subframe and shouting, "It's the diff, you moron!"

I also took a day to drive down to VA Beach and meet up with a guy selling a VLSD housing with a 4.36 ratio.  This came in some base model R32 skylines, and early CA18DET powered S13s and 180SX's.   This is the missing link to the clutch diff a recently picked up.  I'll be able to swap the diff directly into this housing, then have a 1 (or 2) way clutch diff in a 4.36 rear end ratio, and still have the welded as a backup with the 4.63 ratio.  It'll be interesting to see where 2nd gear lines up with the slightly taller ratio.

By some small miracle, the things I shipped are actually starting to make their way here.  Subframe bushings just showed up from Z1,  RLCA ball joints on the way from Faction!, and Eibach's lower rate springs are on a slow boat from CA.   So there's a small chance I can get this heap thrown back together for the event this weekend.  If by some small chance that happens, and you see me there, ask if I filled up the diff with fluid!

I have faith in you! I expect to see you racing & camping this weekend. 

rallyxPOS13 said:

In the background is the mulch from the group of 4 trees that killed my house, die Tulip Poplars, die!

I'm not a fan of Tulip Poplars! I've taken four or five of them down in recent years as they've been putting the house at risk. Did this one last winter - about two years too late. It was badly rotten at the base and kind of sketchy to cut safely.

Interesting on the antisquat stuff- the BRZ rear suspension has similar issues which people solve a simiar way.  Does the S13's trailing link location also impact the bumpsteer significantly when you change it?  That's half the benefit to moving that pickup point on the BRZ.

I'm in the "let's test it and find out" camp right  now.  If I've got time I may run a cycle and plot toe to look for bump.

There's good analytical stuff out there, but most people are trying to fix a messed up alignment from running too low, and I'm very much at the other end of the curves!

Took advantage of some WFH and got the chilled bushings installed over lunch!

The lowers are cupped to match and alignment washer on the bottom, it was a struggle to get those in as the holes were decidedly not circles anymore.  I had to walk them in with the ball joint press.  Once they magically cylinderized the holes again, the tops just fell in with a couple good whacks of the hammer.

All this talk of anti-squat does diddly squat if there's no transfer of weight to the rear.  So I ordered some 162# springs for the back.  Those came in yesterday, and I quickly installed them. 

The stock SE split on spring rates was 123F/123R. So I was running 250F/225R previously trying to be evenish like the stock stuff...  but most aftermarket stuff was split 8/6 softer in the rear, and even Nismo's upgraded approach was 296F/219R. 

So these new springs will get me in that 70-75% softer rear spring than front ratio, letting me transfer weight to the back, while hopefully keeping me off the bump stops.

Decided to run the new ratio VLSD as-is for this event, since there wasn't time to order new bearings and seals.  So I swapped the 4-bolt cover over, and mounted it in the subframe;

New lower ball joints look like they just landed at home, so with a small thrash, should be able to turn this back into a car by this weekend!  
 

*cough cough* I think I may be coming down with something and need to take a sick day tomorrow.
 

Solid work!  Everything's lookin real nice!

Anti squat increases weight transfer on a momentary basis, which may or may not by what you want.  

Other than that, weight transfer is center of gravity and wheelbase, springs won't affect it.  Stiffer front is nice because you can land the car on the outside front entering a turn, and exiting you can carry a front tire if you do it right.

Looking really good! Nice work! Interested in hearing how it works when you get it assembled.

Friday morning was going smoothly.  First I replaced the lower ball joints.  Nissan claims these lower arms have to be sold as a unit, but long ago the Forums determined that the balljoint was the same front balljoint as a Sentra, so I've replaced several of these with Moog Part Number K9633.  These pressed in and out without a hiccup as the old ones had been bathing in penetrant overnight.

I got the arms on, the lowers took some fiddling, as the aluminum conical spacer would get pinched and bent as the stock arms were a bit of a stretch to get lined up right.  I'd have to uninstall, pound the spacers back round again, and then try again.

I was impressed in myself that I remembered it's way easier with these early style S13 finned diff covers with the fill over on the side, it's way easier to fill the diff with the LH axle out and subframe out of the car, and I dumped whatever random 90 weight I had sitting around in the garage:

As I got near lunch things were looking promising to make it to the Saturday session of the doubleheader this weekend.  I was able to position the loaded subframe, raise it teetering on the jack (huge thanks to SWMBO for helping in this, saved me a lot of moving around). and when I broke for some food and to catch a meeting at work, I had the solid bushings started on each stud.

The process from here on out was to get the 5lb sledge out, wail mercilessly on each subframe bushing till it worked up high enough to get some threads exposed on the studs, then start using the nuts to pull the subframe up evenly.  Despite cleaning the car rather well expecting to be working here, each hammer blow brought a shower of mud and rocks.  This was exhausting, dirty work.

And at about this time, life happened:

Poor Yoshimi had an incident with one of her toenails, and after consulting with the vet and getting some X-rays, may have to loose a toe!  With what was to be a quick exam turning into a couple hours, followed by monitoring her for leaving the toe alone.  This dropped the momentum for the day.

I was able to get the car buttoned back up, back on it's wheels for the first time in weeks, and took it for a flog around the local neighborhood.  I didn't get a chance to do much testing or travel checks while it was in the air.  I was initially worried, the new bearings in the LCA seemed 'stiff' but as I cycled it more and more it seemed better.  Despite fears of the rear binding, it felt way better on the street.  The non-welded diff being the biggest difference, but the softer springs and maybe new geometry felt great shooting for bumpy broken tarmac in corners.  I only really ran out to the gas station and took the long way back.  

However at that point it was 9pm, I was exhausted and still had this whole list of packing to complete, and decided to pull the plug on Saturday.  I don't generally camp, so I'd have also needed to run out to the store and buy a bunch of stuff for that.

I'm glad I did bail on today, because I was still plodding along with my checklist and getting the trailer set up at 1pm today.

Oh, speaking of the trailer, I forgot about my last mod:  I added some tie downs to the lower shock mounting location:

This gives a HUGE difference in angle of the aft straps on my shorter trailer.  You can see the normal tow hook location on this side shot, and now we're headed mostly fwd instead of mostly up.

Looking forward to seeing which bolts I forgot to final torque tomorrow!

In reply to rallyxPOS13 : I saw those in an earlier parts picture and wondered what they were. Are they GKTech parts also?  I may have a case of tie strap eye envy!

In reply to madmrak351 :

I think those were from MA-Motorsports, they have a lot of thoughtful fab parts for S-chassis, including front tie downs that pick up the front of the power brace.  They were made for drifting folks who don't have 'normal' bumpers anymore front and rear, but really work for my application with the short trailer and tall ride height.

On to the event! 

The tow in was noteworthy in that I've added an ODB2 sniffer to Slimer to keep an eye on transmission temperatures.  It was a bit scary on the way in, on the long climb up on the way in, it was pretty easy to heat-load the trans.  I was seeing instantaneous readings of 240+ on the converter, and had the total trans temp soaking in the 220 range. (I have no idea if these are bad, or how bad, automatic newb)

On the way home, I adjusted my driving style, and was able to use the manual shifting mode to keep the revs over 3k and had those 20 degrees cooler, lower engine temps, and even seemed to get better gas mileage.  I'm still learning this as a 'truck' and automatic transmissions in general.  Whoever programmed this transmission from Toyota to try and eek mpgs out should be shot, its a fairly miserable pairing to what is a good engine if you can use it like it wants to be driven.

As I pulled into the event, there were not too many folks there from the previous day's event, it had fairly low turnout, and some attrition from Saturday's course.  As I was getting the car prepped for the morning, and chatting with some folks, I found out that Motojunky here on GRM had some issues with brake lines on his Outback Sport and as punishment for breaking his car, offered him a co-drive in the POS13.

In past years of RallyCrossing, I've shared my cars with many different people, and I've had the benefit of a couple folks hopping in this car for a run or two, but for this iteration of POS13, I've never had a full event co-driver.  It was incredibly interesting to see how the car behaved to a slightly more conservative driving style than my usual Clarkson-esque approach of pinning the throttle and yelling "POWER!" at it.   The steer with the rear approach I typically take would leave me out of options if the car got slightly off line, but Craig seemed to be able to adjust line and find grip better than I did.  There were a few corners where the more aggressive approach seemed to be a bit quicker.  One of the downsides of dual driving the car at a smaller event was that we were basically hot lapping the car, without time to sit and look at the results or check anything between runs.  But man, I was having a blast! 

At the lunch break, someone mentioned all the cones I'd hit.  This is typical, and since I hadn't raced in a year I expected the runs to be a bit dirty....   but then I checked the online results: I hit 57 cones?!

That's just in the morning session, I was fairly embarrassed.  That's a crazy amount of cones, I must have been up against a few cone walls and wiped them all out.  I had schwacked a few cones here and there that I recall, but from the driver's seat, it didn't seem to be that bad.

Oh yeah, I made a ton of changes to the rear of the car!  How'd that work out?

• The VLSD diff was much more driveable than the welded, it was immediately different, and would bite you way less.  
• It did feel to me to be more compliant on the rear, and I was able to be more smoothly dynamic with the car.  It was really enjoyable, in the morning session there was a very long LH sweeper down and back up a hill, and I felt I could stay in the throttle with the car sitting at various angles of sideways all the way along that sweeper if I got the line right.
• I was able to rotate the car under braking again, which has been missing from this car the entire time.   
• The gearing change from 4.63 to 4.36 didn't seem noticeable in the car being slower, or running out of gear, the car seemed perfectly happy in 2nd. 
• I don't think I felt anything binding or notice any new things in the cacophony of noise while running.

For the afternoon runs, I calmed down on the cone killing, and Craig and I decided to take a dust break, and let each other run solo in the car.  This let me get a couple shots of the car from the outside!

My last couple runs were clean, the car felt well behaved, and I ran a low 68 which was a competitive time for the afternoon runs.  Best of all, in a day that showed even more attrition, my car drove onto the trailer!

The tow home was uneventful, but I should go buy a lottery ticket.  As I was unpacking I noticed this:

RR trailer tire was at 5 psi, with a fairly large leak.  This must have happened in the neighborhood, because neither tire there felt warm to the touch, or showed any strange wear.

As I was backing the car off the trailer, I noticed that it was sitting a little lower in the back than normal..

Switching over to british horse measurements, I used to have about 1 hand's worth of clearance to the fender lip.  Now the LH side was at 1/5 hand, and the RH side 3/5

Oh well, we dodged whatever has bent, settled, or broke back there!  Further post event analysis to follow...

In reply to rallyxPOS13 :

Thanks again! I was able to pay the favor forward this past weekend by letting a competitor hop in my car for the day when hers broke in the morning. 

Your car was all oversteer, all the time, but not in an unpredictable way. It did what I told it to do - I just kept telling it to do the wrong things. It's just so much fun to steer with the rear. On the ride home I was thinking about whether it was a lack of grip in the rear, or possibly a front end set up thing (caster). The front felt planted, so I'm thinking you'd benefit from finding a little more rear grip. From reading your earlier posts, and Josh's experience in your car, it sounds like you made some good forward progress with the last round of changes. I never felt out of control, or at risk of an unplanned spin.

Your run times later in the afternoon were on pace with the fast guys. There were a couple of places where you were stringing corners together in an absurdly fast way - it was great from the passenger seat. That chicane into the downhill right on the morning course... I can't get my head around your speed through there. 

You dodged a bullet with that low tire for sure. I've been thinking about trailer TPMS systems - this is another nudge in that direction.