17 years and counting...

[JTurbo]

Good update Ted. One of my factory EEC connectors on the firewall has a bypassed wire, I suspect it was a similar issue. But rather than replace the connector, the auto tech (not me) just but spliced the two wires together. Your solution is much better....

I also like your TPS test ports. That's a great idea (I really hate back-probing that connector to set the TPS voltage).

[svono50]

Thanx, I ran across the concept a long time ago and gave it a go. When I was having a batch of electronic issues I added them in and it was a great help. I tore up a section of wire with safety pins and decided I not only needed to patch the damage, but give myself a proper way to check. I will write something up in the electronics section on it.

[gbeaird]

Thanx Gene, they are on my yearly spring checklist to inspect. So far they are hanging in there, but I do expect to replace soon. The Watts made a huge difference with left/right handling as well as any bumps you encounter while in the midst of a turn (i.e.- auto-x parking lot expansion cracks or track rumble strips). Now I need to 'tune' my rear suspension to get better grip on corner exit with some guidance from the C-C crowd of course.

They can help a lot. Are you autocrossing your car? What class? Looks like at least ESP. One secret to getting rear bite is to make sure the lower control arms are level with the ground. I actually like the back mount to be just a bit lower than the front, but not much. It helps bite, but the car is sensitive to throttle lift in corners. The plus side to that is if you know about it, you can apply just a bit of throttle and get the back to hook up again. I haven't felt all that much of the dreaded roll-understeer or roll-oversteer people talk about on the forums if the LCA isn't perfectly level, but do like the fact I can lift off the throttle entering a corner, have the rear rotate just that much more, and usually (if the tires aren't dead) plant again when I reach the desired point in the turn and get back on the throttle. You shouldn't be off the throttle much with a turbo anyway, as even a small amount of positive pressure on the gas pedal will help keep the turbo spun up.

[svono50]

Gene: Yes, I try and hit 1-2 local events every summer. One local group uses a spot just 4 miles from my house, so it is very easy to hop on over for a quick spin. I generally get placed in ESP, but nobody really looks at my setup and I am not a threat to the real competitors. I do get plenty of walk-bys and chat about how folks remember our cars when they were a 'hot' item back in the day. My rear arms are almost perfectly level with the Eibach Pro springs, but I haven't measured to confirm their specific position. I have a feeling the Watts pivot is in a good spot as the car handles pretty neutral, but I am getting some lift on the inside rear which causes me to lose traction on corner exit. I agree with the CC folks that I may have to much rear roll stiffness and will experiment with a little less rear bar. The Eibach unit is a 25mm unit, but I have a GT and the original SVO bars to try out. Depending on the results, I can always lower the rear roll center on the Watts and see what effect that has on my combo.

Funny you mention about throttle control. A couple of instructors at my MVP track days have commented that I should practice left-foot braking to keep my turbo spooled up and launch harder off the turns. I plan on practicing that next year, but I will have to say that I need to practice my foot dexterity to pull it all together smoothly. Of course that could all be to waste if I can't get the extra power to the ground. Need to consider rebuilding the trac-lok or stepping up to a Torsen unit...if I can find one in a 28-spline variety any more.

[ciscokid]

I put a 28 spline Torsen "hi-bias" differential in my SVO this year when I "upgraded" to an 8.8. I bought the unit directly from Torsen, but I see that Maximum Motorsports has them and the price is better than what I paid directly to Torsen.

Bill H

[svono50]

Bill, thanx for the info. I am going to fire up a new thread in Driveline forum to discuss further, so check over there.

[svono50]

PM3L (Poor Man's 3-Link) Rear Suspension

I installed my Fays2 watts link in the fall of 2012 and enjoyed the much more stable control it gave me in the corners for a couple of seasons, but I still wasn’t completely happy. Why you ask? Well, even though going through the corners was much less ‘dramatic’ with a locked in place rear end, I was now having issues getting power to the ground coming out of the corners. I was spinning my inside rear wheel coming out of corners on both the road and auto-x courses (i.e.- high and low speed). This was a bit frustrating as I could go through the corners faster, but I couldn’t accelerate out of them as quickly as before…grrr!

During the 2014 summer I focused on trying a couple of things to see if I could eliminate/reduce the “inner wheel peel” I was getting. I played with the rear Koni shock settings to no avail. I then tried putting in the stock SVO rear sway bar (17.2mm), which did help a bit on the auto-x course, but not so much on the road course. I then started to think that my posi differential clutches were finally worn out, since they have been in there since I put in the 8.8” rear axle 20 year/44K miles ago.

After doing a lot of research over the 2014-2015 winter, which even included a chat with Jack Hidley from Maximum Motorsports, I came up with a plan. The ‘main’ issue seemed to be the old ‘quadra-bind’ rear suspension that was not only fighting itself, but now also the watts link. Jack noted that the same thing would happen with a panhard bar, so what I was experiencing likely wasn’t differential related.

The "plan" included installation of Maximum Motorsports Extreme-Duty Adjustable rear control arms and Wolfe Race Craft spherical differential bushings to compliment my UMI upper control arms that had a poly spherical bushing on the chassis side. The rear would now be fully linked to the chassis through spherical bushings. Those bushings will allow enough movement to prevent any suspension bind, right…WRONG!!

Comparison between MM arms vs stock lowers w/poly bushings and installed:


Wolfe Race Craft bearings:


Eibach 25mm swaybar install/clearances:


Well, in theory the spherical bushings should have removed the bind…if I was still running 4 links in the rear suspension. Issue was that I added a 5th link into the mix with the watts link that ends up creating a competing roll center and arc to the axle housing’s movement. A panhard bar would also create a similar issue, BTW. When I put in the new arms and bushings, I pulled out the rear springs so I could ‘dry cycle’ the rear axle and check if there were any issues. With the chassis up on jack stands, I put another set of jack stands under the axle shock mounts to hold it at normal ride height. Then I lifted up one end of the axle to kind of simulate the chassis pitching in that direction (i.e.- going around a corner). I noticed that as I lifted the axle end the force to raise it was more than I could do by hand…hmm(??). I put the jack under the brake disc and pumped it up slowly. Everything moved up smoothly, but then the disc literally jumped upward off the jack’s pad and came to rest ~4” above it…WHOA, WTH!! Note that the other side of the axle was still sitting on its jack stand. I removed the jack and pushed down on the axle by hand. The axle moved down smoothly with an increasing amount of force then suddenly dropped away from my hands smacking down onto the jack stand, similar to what it did in the upward direction. I repeated this exercise on that side again with the same results to confirm what I saw the first time. I then tried the other end of the axle with the exact same results, so the phenomenon was happening on both sides in a symmetrical fashion. I also noticed that the watts brackets bolted onto axle tubes appeared to be flexing during this suspension movement…not good. The maximum amount of resistance force appeared at 2” of axle end movement, which equates to only 1” of twist of the axle relative to the chassis. This is well within ‘normal’ movement of the rear axle in a corner. I then removed one of the watts link bolts from the axle bracket and proceeded to move the axle end up with the jack. I moved it up to the 2” mark and held the watts link up to the axle bracket…the bolt was offset ~1” from the bracket (see below)! That would certainly explain the force, jump and bracket flex I saw. I moved the axle end up till the axle contacted the chassis bump stop pad (5+ inches) without jumping off the jack’s pad. I put it back down and tried picking it up by hand again, this time I was able to move it up to the bump stop and back down without any change in force. I bolted the watts link back up and removed the driver’s side upper control arm to see if things would still move without the bind as it did with the watts link disconnected. I was happy to see that it moved smoothly without any bind on either side with only the passenger side link, proving out the PM3L (Poor Man’s 3-Link) does indeed work and is necessary even with all spherical suspension arm links.

Amount of offset due to bind:


At the time of this writing, I have been running the spherical bushings and PM3L for 2 summers/seasons without any chassis stress related issues on either my torque boxes or upper mount. Now, mind you I don’t run my car at the drag strip or normally drag race launch the car on the street either, so my impact hits on the rear suspension are not severe.

While I haven’t had any chassis related issues, my issues moved from a binding rear suspension to now having too soft of a rear suspension. Even with the Eibach 25mm solid rear bar on the car I was still having understeer issues through the corners as compared to a really neutral feel with the binding rear suspension. Losing the extra spring rate from the suspension bind now left me with the rear rolling over too far and moving toward the understeering tendency I had worked so hard to get rid of…oh the horror! I did, however, gain back my ability to power out of the corners without lighting up the inside tire, which confirmed that my differential clutches still have some life left in them. This led me into the 2015-2016 winter with more research to do along with another project...

[svono50]

Maximum Motorsports Rear Torque-Arm Springs

As I left off with the last project above, this one came about due to the new found understeering tendency of my SVO which in turn was due to the freed up rear suspension. One cure simply leads you to the next problem that needs to be solved! Once again, I hit the research trail over the 2015-2016 winter to see what an appropriate solution was to my ‘soft’ rear suspension. Another lengthy electronic chat with Jack Hidley brought me to the realization that my Eibach Pro rear springs just weren’t stiff enough now without the binding that was going on. Based on the Eibach Pro front spring rates, the best match were the ‘lower’ rate torque arm springs offered by Maximum Motorsports (#42TA5). The MM TA springs are 375-440 lb progressive rate springs as compared to the Eibach Pro 200-251 lb rating. I was a bit concerned with increasing the rear spring rate by ~75%, but was assured that a non-binding suspension needs a spring rate much higher than expected and that their testing showed it would take care of my understeer issue. I trusted their advice and placed my order for the rear TA springs.

Since I had the MM adjustable rear arms, I didn’t worry about having to compensate for the possible ride height difference between the Eibach and MM TA springs. I measured my ride height, put the car up in the air, swapped out the springs and dropped it back down. Hmm, they look pretty much the same ride height, interesting. I took it out for a quick road test and to settle them in a bit. The most interesting part was that the car only felt marginally stiffer in the rear, barely noticeable to my butt dyno. With the front Koni’s set ‘street’ soft and the rears almost full stiff, the car would ‘hobby-horse’ a bit over bumps on the Eibach springs. With the MM TA springs in the rear the car no longer undulated over bumps and seemed to absorb bumps better…weird! Pulling back in the garage, I measured the rear ride height and it was spot on with the Eibachs…even more weird! Looks like the crew at MM tagged a winner of a spring rate, now to the testing (i.e.- proof is in the pudding).

Comparison between the MM TA and Eibach Pro rear springs:


Installed MM TA spring and yes, those solid stacked coils at the top are 'normal' per MM:


My first test finally came at a track day on the Autobahn CC road course in August. All I can say is that my car responded positively to the MM TA springs and brought the car back into a neutral handling scenario. The understeer was gone and things were back to more of a smooth 4-wheel drift when pushing too hard through a corner. The car also felt ‘flatter’ as it entered the corners, which was a sign that the rear suspension was no longer rolling over. Rear end twitchiness was also reduced when hitting the brakes hard in the braking zone. Lastly, I could easily power out of the corners without spinning the inner rear…whew, what a relief that the rear springs worked as expected!

My second test was at the SVOCA Reunion auto-x event in September against some stiff competition from some fellow SVO competitors. Once again, the car was very neutral in the handling department through the quicker corners/transitions on the auto-x course. I held off the 3 other competitors till the last run when Dave Schmitt pulled off a great run and got me by 0.406 second. Oh, did I forget to mention he was on Hoosier A7 slicks and I was on RE-71R street tires!?! I was honestly expecting to lose to Dave by quite a bit more, but will chalk up the smaller gap to the suspension work I did over the past couple of years ;-)

To sum things up, if you get rid of the inherent bind in your rear suspension, you WILL need to install higher rate rear springs to balance it out with the front spring rates, regardless what they are. To me, the Eibach Pro kit front springs (457-571 lbs) are a good match with the lower rate MM TA rear springs (375-440 lbs). Having rear springs that are ~80% of the fronts on a Fox chassis seems a bit counter-intuitive, but it is working well for me. The original Eibach Pro kit had rear springs that were only ~44% of the front spring rate!

[svono50]

Schroth Rallye-4 Harness #1

As I began to participate in more HPDE/Track Day and Auto-x events, I really got tired of trying to hold myself straight in my seat. I tried cinching my seat belt tight, pushing myself into the seat with the dead-pedal and bracing my knees against the door and center console, but you always had to use your legs for something else (i.e.- shifting, braking, etc). With a harness you can focus all your energy on driving the car. You WILL have to re-calibrate your feeling of your car, as now you can remain a lot more relaxed in the seat. Not realizing this at my first auto-x with my harness, I almost shot myself completely off course on the first turn because I entered it at a much higher rate of speed than I should have because I no longer had the cornering force pushing me off of my seat cushion as a judge of my speed.

My research brought me to the Schroth brand and its Rallye-4 bolt-in harness. I was mainly attracted to it, because it was a simple bolt-in harness that still allows you to use your stock 3-point belt and carry a passenger in back if needed. This harness has a special folded flap of webbing on one of the shoulder straps (ASM feature) that allows your body’s torso to twist slightly during an impact like what your stock 3-point belt allows. This slight twist prevents you from submarining under the lap belt and eliminates the need for a 5th strap (i.e.- crotch strap). Schroth has a video on their website showing how the ASM flap works on a test crash sled. This harness is also DOT approved if you really want to use it on the street, but I don’t recommend it.

To start, unbox your harness and read through the instructions to understand about how to mount the attachment brackets. Don’t just use my pictures as an example, it is a good thing to best understand what you are putting in. Next I recommend removing your front seats, rear seat cushion and rear seat backs to give plenty of clearance and elbow working room.

I worked from the rear forward. Remove the rear seat belt mounting screws with a T50 Torx bit. You may need to soak the screws with some WD-40 under the car first if they have never been removed. You will have to bend the retaining brackets on the harness in a vice or with a large pair of pliers to get them to line up properly with the floor/belts. Bending these brackets to a point is OK per the supplied instructions. I angled mine to have them aim the harness straps out the stock openings in the rear seat cushion. Once the rear straps are installed, reinstall the rear seat to check the strap routing and adjust as needed.



The front straps are even easier than the rears. You will use the same T50 Torx bit to remove the screws and if need be, soak with WD-40 under the car. Only a slight bending of the brackets is needed for the front routing to clear the carpet and stock seat belt ends. You will need to adjust their forward angle to match where you set your seat to prior to tightening down the mounting screws.

[svono50]

Schroth Rallye-4 Harness #2



Now adjust out all the straps and then install the front seats back in place. Sit in the seat, adjust it to the proper front/rear location and see if the front strap brackets are in the correct position and adjust as needed. Sit back down, connect the lap buckle and tighten down the lower straps to center the buckle. Now you need to figure out where to adjust the rear strap to allow proper positioning of the shoulder straps. This step will likely take a few times to get it just right where the Y-section isn’t against the seat back and you still have some room to tighten up the shoulder straps once seated. You should be good to go out and tackle your favorite course or even back-road in a more physically relaxed state.

One aspect you may not realize when you are strapped in with a harness…you cannot reach any dashboard controls, only your rear view mirror, steering wheel and shifter are in reach! So just make sure you have everything adjusted with your radio, lights and heating controls BEFORE you synch up the straps…ask me how I know.

If you plan on racing with any local sanctioning group (i.e.- SCCA, NASA, etc) make sure whatever belts you install are legal for use with that sanctioning group. From my own research the Rallye-4 harness is legal with SCCA, but is not legal for use with NASA. Another thing to consider is if you only want to install a harness on the driver’s side. I found out that some HPDE/Track Day groups will not allow you to use the harness if an instructor rides along with you. The reasoning behind this is that the instructor wants the same crash protection as the driver, which I can completely understand. If this is the case, you would need to use your factory 3-point belt for the session(s) where you have an instructor riding along or install another harness for the passenger as I decided to do.

[gbeaird]

Ted,

Nice work up. I did something similar to our 86 when we autocrossed it, only didn't have the cool rear seat mount you have, I simply ran the shoulder harnesses from the back seat seatbelt anchors to over the front seat. I used a simple loop of velcro to keep the shoulder harnesses from 'disappearing' when not in use, and it did very well keeping everything in place.

I'll note here that I think the shoulder harness angle might be too severe. It can lead to spine compression in a head on incident. You might want to check that angle to verify, as some DE events won't let you do that. I know they're a bit more relaxed than other wheel-to-wheel events, but it depends on their history and the power of their flying monkeys (lawyers).

That said, they're fine for autocross, and like you say, really help with car control. Another thing you can do is roll up a beach towel and wedge it between your left leg and the door. That helps prevent you from working the window switch with your left knee. Ask me how I know.

[svono50]

Gene, thanx for the tips/hints, they are certainly noted. I know all about rolling windows up/down and even windshield wipers in the middle of a run too!

Folks have talked about the rear strap angle and I researched it before purchasing these. I wrote to Schroth to ask about that and they felt that while having the straps straight back or as close to it is necessary for a typical harness, the ASM loop in their rear strap mitigates the spinal compression when combined with the seat back. If your shoulders are well above the top of the seat back and/or the straps are at an even steeper angle, then they suggested staying away from using the rear belt anchor points. They gave our Mustangs a pass rating on the rear belt anchors combined with my shoulder to seat back alignment. If I had a more seriously dedicated track vehicle I would have a harness bar at the proper height behind the seats with 3" straps, that is for sure, but for my occasional track/auto-x events, I am confident they will perform as Schroth intended them to.

[gbeaird]

Ted,

It's good to know the seat backs help the issue. I just wanted to point it out in case someone else reads this and sees it as a solution for their road racing endeavors, only to fail tech at the event.

[svono50]

Ted,

It's good to know the seat backs help the issue. I just wanted to point it out in case someone else reads this and sees it as a solution for their road racing endeavors, only to fail tech at the event.

Gene, great point! The Rallye-4 & 3 variants were never intended for 'competition' applications, only as a way to better hold you in place for more 'amateur' events like auto-x and HPDE kind of events. If you plan on more serious road racing type of events, then you should consider an appropriate roll bar setup with a harness bar along with a 5 or 6-point harness.

[SVOeric]

That's the concern with this type of setup. it holds you in place, but doesn't offer the protection of a cage in the event of an accident (IE:Roll-over)

I toyed with the idea for years of a bar that went from the rear seat bolts, up to the seat-belt bolts, then across the top of the car, with a secondary bar for the harness to clamp on. same issue however, it might protect over the drivers head, but don't keep the windshield from smashing down.
all kind of a worst-case scenario, but always prepare for the worst...