LS4 / F40 swap - fieroguru (Page 95/216)
fieroguru JUL 07, 08:49 PM
My garage is now empty, so I can get back to doing some minor upgrades to this car. The main things I would like to get done this summer and before LS Fest in September:

Upgrade shifter cable to stronger version.
Swap stiffer springs front/rear
Replace the rear struts with Koni's (on order) and adjust the front Konis to full stiff.
Swap nicer dash and interior from 86 parts car along with the PW/PL

I started working on the cable upgrade a little while ago and documented most of the details here:
http://www.fiero.nl/forum/Forum1/HTML/094069.html

The things I wanted the new shifter cable to solve were:
Stronger cable - don't want to break it again.
Proper length - old setup had one cable 4" longer than the other.
No more c-clips - had them pop off twice.

The short version is the stock Isuzu shift cable is the prefect length, it just needs the smaller ball end. Rodney hooked me up with a new isuzu cable and the right ball end. Then I fabbed up a new shift bracket to work with the Isuzu Shift and Getrag select cables using shaft collars (with machined grooves) to hold both shift cables in place. The 5 speed shifter works great and doesn't need to be modified at all. The only thing it needs is a reverse lockout.

New shifter bracket:




5 speed shifter with reverse lockout added:




New shifter cable routing (both are now the same length):


The 5 speed shifter places the gears closer (longer select lever), the shifter cable is certainly more firm shifting into 3rd, and the shaft collars will keep the cables firmly attached... so far I am really liking the upgrade, but need to do some 7K RPM upshifts to know if it will help my 1/4 mile performance.
ericjon262 JUL 07, 08:54 PM
I love the brilliantly simple reverse lockout.
Steel JUL 08, 07:47 AM
You do brilliant work... I really enjoyed your threads and learned a lot.
fieroguru JUL 11, 08:25 PM
I have been driving the car to/from work and other joy rides and really like the new shifter/cable/bracket setup. It feels like a completely different transmission. The gear spacing is tight, but the 2-3 shift just falls into place, and just feels right. The shifts feel less clunkier too. The detents feel softer as I go into each gear. I think using the select cable allowed the cable to flex slightly as the detent was depressed and made it "feel" harder. Now with the stiffer cable, I can pass through the detents with less effort. I suspect the stiffer cable provides for higher impact loads to depress the detent vs. the cable flexing and having to more slowly force them to depress.

These came in earlier this week ($341.16 shipped from Amazon), but it will be a week or two before I mess with them.


This weekend I am going to play with the front springs. The tall tapered ones have .540" wire vs. about .5" for normal Fiero front springs. The wide end ID/OD is compatible with the fiero, but the small end works with coil overs. Right now I plan to cut the small end off to get the proper ride height (and a stiffer rate than I am currently running), but some day I may use another set for the front coil overs. I can't remember the stock application for these springs, so I will have to try and find it in my notes somewhere.


fieroguru JUL 12, 01:16 PM
The conical springs are Moog 7634 from a 99+ Chrysler Cirrus and they cost about $55 for the pair. In stock form they are 13.5" long and have a spring rate of 265 lb/in. I cut them down to 9 1/2" long which should increase the spring rate to 350-370 lbs/in. Here is a cut one along side the stock Moog spring, the cut down 84-87 front spring, and an 88 lowering springs of some brand (suspect fiero store). As you can see the new cut down spring is shorter and the car ride height is just about the same (slightly taller to allow for some settling).


The front springs and adjusting the front Konis to be full stiff (on rebound - no adjustment for compression) really cut down on the movement of the front suspension. The front ride is firmer, but still isn't harsh, but I still have stock rubber front bushings (eventually those will be changed).

My car has close to the factory curb weight and weight bias, so I want to keep the relationship of the spring rates front/rear the same.

Stock 88 Spring Rates:
Front: 205lb/in
Rear 142 lb/in

New front spring rate of 360 lb/in is 1.75 times stiffer, so the rear spring should be 1.75 times stiffer = 249 lb/in. My current rear coil over springs are 275 lb/in and that is close enough for now. So all I need to do is modify the rear Koni struts to accept my current coilover springs.
fieroguru JUL 12, 03:56 PM
Chucked up the struts in the lathe so I could turn down the top cap so the coil over sleeve would fit over it:


Then cut off the stock spring perch:


I left the weld bead in place and will use it to support the coil over sleeve. Eventually I will maximize the rear tire width and the backside of the wheel will not clear the coil over spring, so it needs to stay higher on the strut:


Test fitted the sleeve and they are about 1/4" too long. So they spent some time on the lathe as well:




Then they were taped off and painted. I didn't have a color that would match the Koni red, so the silver will blend in to the aluminum sleeves:
fieroguru JUL 12, 07:08 PM
Rear struts are installed and set to full stiff:



The adjustment nub that sticks out of the end of the shaft was interfering with the flange on the vents (flipped strut bushing). Since I don't use any hold down bracket on the inside of the vents, I just cut the flange off.
infinitewill JUL 12, 10:02 PM

quote
Originally posted by fieroguru:




Paul,

I'm confused. What is holding your vents down now? Don't they rattle around on rough roads?

Dr. W.

[This message has been edited by infinitewill (edited 07-12-2014).]

fieroguru JUL 13, 07:36 AM

quote
Originally posted by infinitewill:
I'm confused. What is holding your vents down now? Don't they rattle around on rough roads?



I stopped using the inside rear mount for the engine vents in 2003 for most of my personal Fieros and haven't had any issues. They stay in place quite well and don't vibrate. On the notchies, I still use the hold down bolt on the outer edge and both front attachments - so they are supported on 3 of the 4 corners. On the GT fastback cars, I don't use any bolts and they are only held in place by the tabs on the outer edge that lock into the sail window trim. The fastback vents also have an inside tab with rubber bumper on them so the decklid can hold them down and keep them from vibrating.

I started doing this because I converted an 88 notchie to a GT fastback and didn't have the 88 specific mount for the fastback vents. Since I didn't have it, I went ahead and cut the mounting tab off the upper strut tower ring to clean it up and also modified the struts to use button head bolts vs. studs. It really cleaned up the visual appearance of the top of the struts and also allowed me to quickly remove the vents and display the car w/o vents at car shows.
infinitewill JUL 13, 11:49 AM
Ah, now I understand. I was also wondering about the rear lateral link relocation you did. What do you calculate you will be able to use for rear wheel width? IIRC you are using stock rear quarter panels correct?

Dr. W.

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