LocostUSA.com

A drawing would be great MiataV8! I think I get what you are saying but I am more visual.

On another note today, I am starting to mock up where the engine, transmission and steering all will sit. My trans tunnel will need to either be redone or altered slightly. I am probably going to shorten and use the RX8 PPF, unlike a Miata one the RX8 is made of steel so altering it should not be too bad, plus it will probably take a ton of stress out of my frame.

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Convincing yourself you can do it is one thing, convincing your wife it is a good idea is another. Glad I have a great wife!

1999 Dajiban build
Autcross car currently 2009 Mazda RX8 R3.

Build is a plus 4" width, 13B Renesis. Wish me luck.

A little work to make the jig but well worth it. It might also come in handy if you bend it in an accident or if you or someone you know wants to build another later.

If you are replacing the bushings, use a hand torch on the bushings to separate the inner sleeves and use those in your jig (if not reusing with custom bushes). Sometimes the burning rubber will pop them out by themselves. Super easy to do.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

So the rear is down on the ground.

I am struggling to figure out the front as I really do not want to cut the steering rack, it just does not sit well with me. The problem is the RX8 suspension mounts are approximately 15cm wider each side then my locost mounts would normally be. I want to keep it close to original track width (1500mm) as the rear is stock width (1505).

MiataV8 I appreciate how you have said to do it, just that rack shortening is not something I am willing to tackle right now.

_________________
Convincing yourself you can do it is one thing, convincing your wife it is a good idea is another. Glad I have a great wife!

1999 Dajiban build
Autcross car currently 2009 Mazda RX8 R3.

Build is a plus 4" width, 13B Renesis. Wish me luck.

Make an EBay search for "rack, pinion, (appleton, coleman, sweet, woodward)". Sometimes you might get lucky in that market.

Part of your experience will be determined by the length of the steering arms out by the wheels, as well as the diameter of the steering wheel. A quick rack, with short steering arms and a small steering wheel might equal an undrivable car (especially without power steering).

Having said that, here are my research notes (feel free to help me perfect them):

******************

Rack speed is measured in inches per turn. If you turn the pinion (1) time, the rack shaft will move between 1-3/4" (slow) and 3-1/4" (fast).

The f body had 2.25 lock to lock and 2.75 lock to lock ratios.

Two Ratios: 2.9 (recommended for road use) and 2.4 (recommended for racing) the f-body rack is 58" while pre 88 fieros were 52" for entire length with ends.

Escort Mk2 Steering rack for use on the Haynes Roadster. The inner ball joint width that I measured was 585mm. Escort rack is the right length (inner balljoint to inner balljoint) for the +4" chassis... the Escort is within 6mm of being perfect for the McSorley 7+4 chassis and hence it must be 94mm too big for the standard chassis.

Chevette rack is 3.75 turns lock to lock with 6" of rack travel over those 3.75 turns. Based on this the rack is traveling 1.6" per turn 6/3.75=1.6.

Fiero is 3 turns lock to lock.

The 'un cut' Chevette rack is pretty close to 41" tip to tip. I had to cut about five threads off each end for my fitment. The pinion shaft tube base starts right at 11.5" in from the end if the rack. As far as angle, that is only a guess from eyeballing it. I would say around 5 to 7 degrees angle off the rack body. 26" as measured from feeling through the boot. Per rough measurement, Chevette is, approximately, 24 3/4". The one I have is about 25" C to C on the inboard ball joints

Front steer:
- Chevette rack (need to be shortened)
- Miata (need to be shortened)
- MGB
- Triumph Spitfire
- Porsche 914 (center-input)
- RX-7 Gen II shortened 4.5"
- Volvo 240 shortening??
- BMW 3 series shortening??
- pre 84 tercel

84' Mustang. It is front steer however... I found that pinto rod ends will bolt right onto the Mustang rack and reduce its width by about 2" inches on each side. This works perfectly on my book +4 chassis.

The F Body rack "Body" is 22.25" from stop to stop. The body itself is the steering stop.
The F Body "rack gear" is 27" from stop to stop. The inner tierods have a plastic bushing that acts as a abocusion for the bump stop. So this is the lenght of the rack with the inner tierods on it.

The F Body total travel is 4.74
The F Body WS6 takes 2.25 turns lock to lock.
The F Body has 3.75" of rack body on the left side of the pinion.
The F Body has 18.5" of rack body on the right side of the pinion.

The Chevette rack body is 17.75"
The Chevette rack gear is 23 3/8"
The Chevette total travel is 5.65"

The Chevette has 2" of rack body on the right side of the pinion.
The Chevette has 15.75" of rack on the left side of the pinion


The 88 (Fiero) rack body is 24.25"
The 88 rack gear is 29.25
The 88 total travel is 5.1
The 88 takes about 3.4 turns lock to lock
The 88 has 2.75" of rack body on the left side of the pinion.
The 88 has 21.5" of rack on the right side of the pinion.


The 87 (Fiero) rack body is 23.75"
The 87 rack gear is 28.25"
The 87 total travel is 4.6"
The 87 takes about 3.1 turns lock to lock
The 87 has 2.25" of rack body on the left side of the pinion.
The 87 has 21.5" of rack on the left side of the pinion shaft.

Mustang II
Mustang II A-arm spindle = aprox. 4-7/8"
24.5 from tie rod socket to tie rod socket

Flaming river MII
4.00 turns lock-to-lock,
rack travel 5.25",
overall length 45",
inches per turn, 1.3”

Factory Pinto.....
4-1/8 to 4-1/4 turns lock-to-lock.
One full pinion shaft turn = aprox. 1.262" of rack travel.


F-body: 4.74/2.25 = 2.106"/turn
'88: 5.1/3.4 = 1.5"/turn
'87: 4.6/3.1 = 1.48"/turn
Chevette: 5.65/3.5 = 1.614"/turn


power-steering Miata rack Total travel = 4.71"
2.66 turns lock-to-lock.
26" pivot to pivot.
Speed = 1.77"/turn


Rack and Pinion Ratio Chart

1.57 inches per turn:
Very slow steering, mainly for superspeedways or road courses (GT classes) where top speeds exceed 160 mph. Ordinarily applied as manual steering. Also used to compensate for the short steering arms on small cars. With long steering arms, the overall ratio can range down to 24:1. For power steering with this rack on short tracks, use a #850 or #855 servo valve with a KRC standard 7.2cc pump and #8 and smaller output fitting; The same servo valve with a KRC 5.9cc pump and a #4 or #5 fitting will handle a ratio like this on superspeedways.

1.83 inches per turn:
Slow steering for paved tracks 5/8 mile and over; usually run as manual steering. Formerly popular in GT classes, as this ratio closely approximates that of OEM sports car steering when used in conjunction with short steering arms. Use #850 or #855 servo valve with KRC 7.2cc or 5.9cc pump and #8 and smaller output fitting.

2.09 inches per turn:
Formerly the most popular ratio for manual steering pavement applications in both stock car and road racing. Known as the 16:1 rack, it feels about like a Corvette. Used with power assist about half the time.

2.36 inches per turn:
Quicker steering for paved tracks, especially those 1/2 mile and under. Useable as either manual or power steering, although run as power steering in 80% of cases. Its overall ratio usually works out to around 14:1. For power steering, use a #855 servo valve with a KRC 7.2cc pump #7 and larger output fitting

2.62 inches per turn:
Ten years ago this ratio was commonly used as manual steering on dirt late models. At 12:1, it still gives relatively easy steering on dirt, and is the best entry-level choice for manual steering limited late models. It's most common application today is on pavement with power assist. Use a #855 servo valve with KRC 7.2cc pump and #8 and larger output fitting.

2.88 inches per turn:
Quicker than average manual steering for dirt tracks. At about 10:1, this will require setting the car’s caster and camber for minimum effort, unless power assist is used. Much faster steering than any road vehicle. For power assist on pavement, use a #855 servo valve, on dirt use a #850, with a KRC 7.2 pump and #8 and larger output fitting.

3.14 inches per turn:
For powersliding around bull rings. This is about the fastest ratio usable as manual steering (and was considered radical in the early 1980’s). If used without power assist, most front ends will need the positive caster backed way off to street-vehicle levels (under two degrees), and the caster split reduced.

3.40 inches per turn:
Very quick response; generally applicable only to dirt and only with power assist. Cuts your reaction time in half if you’re ready for it.

3.66 inches per turn:
Instant response with even less wheel movement, standard equipment on many new late models. Best with large amounts of power assist, such as 100-125 PSI.

3.92 inches per turn:
See Figure 7. Needs a soft torsion bar (220 and smaller) and a KRC 9.6cc pump with #10 and larger output fitting.

The Chevette rack has a 3/4" 30 Spline male head coming from it. and the Old Fiero rack uses a 3/4" DD... DD rod and Vibration U Joint from Flaming River You will need the U-Joint to be 3/4 " - 30 X DD (PN# FR1814 3/4"-30 X 3/4"DD)

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***************
Geek49203 aka
Tim Wohlford
Louisville, KY
Hayes front, S10 +2 rear, Lalo body.

Wow, great info!

I am getting tempted to integrate part of the factory front subframe. It will give all mounts for upper control arm, I could use the RX8 un modified steering rack, my front sway bar mounts are there already, the top "platform is a great headlight mount base. I then only need to make rear lower control arm mounts.

I would plan to cut the subframe with groves so it could sit down one more inch and back about 1 inch. Then weld it in. This would not be the prettiest set up as the bulk sits outside the body but it would be strong, add rigidity to the frame and removes guess work.

Maybe a donkervoort style front end could clean up the look, or wing fenders instead of cycle fenders.

Feed back?

_________________
Convincing yourself you can do it is one thing, convincing your wife it is a good idea is another. Glad I have a great wife!

1999 Dajiban build
Autcross car currently 2009 Mazda RX8 R3.

Build is a plus 4" width, 13B Renesis. Wish me luck.

One thing to keep in mind is that the EPS controller looks for vehicle speed over CAN, and the ECU uses the wheel speed sensor data that the ABS (or DSC/TC, depending) unit sends out to create the VSS message on the CAN bus. I'm not 100% certain if EPS goes into limp without a valid speed signal, but some forum posts say it does.

The required messages that need to be sent over the CAN bus for vehicle speed are known and collected on the mazda can bus reverse engineering project site.
That data could be levereged to roll together a translator that outputs wheel speed sensor data for the ECU to convert. Bit of a rabbit hole.

My build is set to use the factory rack and EPS controller as well, and I'm honestly thinking the easiest solution is this:
Ziptie the ABS module someplace, feed it power and wheel sensors from the stock loom, along with all it's other electrical stuff, but don't plumb it into the brake system. Just let it act as a translator box, albeit a heavy and inelegant one. Maybe remove the valve block, use the bare control module, and see if it still translates the speed sensors?

My '8 is in winter storage now, or I'd try unplugging the ABS unit to see if EPS drops out.

Sorry for the wall of text.

That will work great. I'd cut the bottom left front chassis tube (which only supports the nose and radiator) that hits the rack mount and run it straight back to the inside of the mount. I'd also notch the bottom of the sub to clear the chassis tubes and gusset from the sub top to the chassis rails on each side and call it done. I would not bother with welding into the chassis along the sides, just the top and bottom. If you want one inch less ride height than the rx8 and are running the same tires and rims, leave the bottom of the sub above the chassis rails.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

So it is official, I'm integrating the subframe. It will be bolt in after all. I do not need to notch it, and the steering rack fits in. The steering shaft is going to go right through one frame piece but I think I can create a solution for that. Also I believe my best solution for the front shocks is going to be a push rod setup. Here is a mock up of it so far. It has been cold (-30 C or -43 C with windchill) and my garage is not heated so progress has been very slow.

_________________
Convincing yourself you can do it is one thing, convincing your wife it is a good idea is another. Glad I have a great wife!

1999 Dajiban build
Autcross car currently 2009 Mazda RX8 R3.

Build is a plus 4" width, 13B Renesis. Wish me luck.

One thing solved another problem comes...

I am actually having clearance issues still, I thought it would all work but no luck. The subframe once the mounts have been made can't come in or out, no problem I could just weld it solid, but then the steering rack can't come in and out. If I'm integrating this bulky subframe, how important are my LA LB tubes? MV8 are these the ones you suggested cutting?

P.s. my FU1 has to be cut to have a tube put in it for the steering shaft to go through already.

_________________
Convincing yourself you can do it is one thing, convincing your wife it is a good idea is another. Glad I have a great wife!

1999 Dajiban build
Autcross car currently 2009 Mazda RX8 R3.

Build is a plus 4" width, 13B Renesis. Wish me luck.

I assumed you were going to weld it in. I suggested cutting and realigning the forward end of f1 if you were going to sink the sub into the bottom rails but I think above it would be better for the desired ride height.

Looking at the previous pic, it doesn't appear that rack removal would be a problem sliding it out the side.

The front tubes support the nose and radiator if you hang them off it, and normally the ucaps but not in this case. You could cut them off depending on how you weld it together but then you'd need something for the nose and the radiator mount. How about a pic of exactly where you are wanting to weld it in (if different from the previous pic)?

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

So I'm thinking of welding on the red lines, and cutting a relief on the blue line so the steering rack will fit through. It won't as it sits right now.with this set up my front wheels are about 3 inches back of what a traditional locost does. As the centre line for the lower a arms for a book build seems to be half way between LA/B and FU tubes.

Alternative is if I remove the LA LB tubes getting a new uncut front subframe and having my front wheels 3-4" further forward, and then I don't have to fabricate rear control arm mounts. This also makes the front subframe a bolt in rather then welded in.

_________________
Convincing yourself you can do it is one thing, convincing your wife it is a good idea is another. Glad I have a great wife!

1999 Dajiban build
Autcross car currently 2009 Mazda RX8 R3.

Build is a plus 4" width, 13B Renesis. Wish me luck.

Can you make the rad support stuff bolt-in?

Or maybe make a rad support frame, and join it to the rest using rubber mounts?
You could probably make it lighter weight and less bulky, since it's going to be bodywork hanging off it, and the subframe is acting as the front stiffener.

I like the idea of a bolt-in subframe a lot more than a weld-in.

It looks to me that if you use the rx8 L-shaped lower control arms, the front wheel center will be very close to where it should be, centered on the forward lcap.

I'd weld in the sub and make brkts for the lca rear leg pivot, cut as needed around the fat rack and radiator up against the sub and rack (or behind the sub if you have room), then fit the nose as close as possible to the sub, notching the sides for the rack bellows. IMHO, a shorter front always looks better but a more protruding nose does not.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

I'm gonna take your advice MV8. Thank you a whole lot for your input.

This forum to me is a phenomenon of the internet, no one gets into arguments, or feels a need to be a ****. It is wonderful and a big thank you to all that contribute, have advice, and for posting your own issues (car related) that others can learn from.

Cheers,

Ben

_________________
Convincing yourself you can do it is one thing, convincing your wife it is a good idea is another. Glad I have a great wife!

1999 Dajiban build
Autcross car currently 2009 Mazda RX8 R3.

Build is a plus 4" width, 13B Renesis. Wish me luck.

Whenever I feel the need to be a ****, I go to FaceBook. I fits right in there with the rest of the ***s!

So, is the plural of **** really ****s, or is it like "deer" and the plural of **** is ****???? Surely someone in here knows the answer!?!?!?


JD **** Kemp

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JD, father of Quinn, Son of a... Build Log
Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom