Vega
crazed

The Following is transcripts of
email correspondence I've had with an engineer who is also an experienced
Vega modifier    "Gary Derian"
<[email-masked]>

Intro
Gary's Vegas
Vega Mods Power2weight

Engines etc.   Exhaust

Torque arm ideas
Torque Arm engineering
Suspension/Steering
Chassis tuning
Tranmissions

Vega? Did you say Vega? I have 3 Vegas, all 5 speed
'76's. One is a stock daily driver red with yellow flames wagon. One
is my son's 229 Chevy V-6 Viper blue with white stripes, Camaro
brakes, Corvette wheels, etc. The third used to have a 215 Buick
aluminum V8 and was to get s 350 HO but I've abandoned that project
to install a Cosworth Vega engine for my younger son. I still have
the engine mounts and bellhousing to fit an old rwd style Buick V-6
if you're interested. I also have the 350 HO.

What I know is that GM used the V-6 in rwd cars to 1987. This
engine used the old rwd Buick-Olds-Pont bellhousing pattern. GM
began using the Buick V-6 in fwd cars in '82 or '83. There was 2
versions ofthe 3.0 Iiter, a short stroke and a longer stroke. This
engine used the new fwd style bellhousing pattern, a smaller crank
bolt pattern, and I think the starter is on the other side. I
believe starting in 1988 or so, the new generation engine for the
full size fwd cars had no distributor, port injection, and the oil
pump was now directly driven by the crank like the original Vega
engine. Also, the cylinder banks were shifted to align the
connecting rods to the middle of the pistons. They were misaligned
since the even fire engines were built in 1977. Later, I think in
1992 or so, the engine was redesigned again with a lower deck
height, shorter rods, and a balance shaft among other changes. This
is the current form used in the Camaro.

I don't know the engine mount location or bellhousing pattern of
the Camaro engine but I think is uses the fwd bellhousing pattern
and a special bellhousing to mate to a rwd tranny. There have been
many changes to the current generation Camaro drivetrain. The
trannys had integral bellhousings for a while but I think they now
have separate ones but different than the old type. If you have no
parts, the best bet would be to install a complete Camaro setup from
a donor car. If you have lots of old style Chevy parts you should
probably build an old style drivetrain with an older rwd style
block.

Another option is the 4.3 V-6 from an S-10. This is 3/4 of a 350
and has always used the same Chevy style bellhousing pattern. The
current Vortec version of this engine has a balance shaft and the
good modern type fuel injectlon.

I am
certainly not rich but I am an engineer.  I am a mechanic as a
hobby.  The brakes on the Vega are a combination '69 Camaro,
actually from a '74 Nova, on the front and '80 Cadillac Eldorado
rears.  I chose these to get a 70/30 brake distribution without
a pressure regulator.

The front calipers have been used on many GM cars from 1968 to
1998.  There are some minor differences over the years such as
metric fittings on newer ones.  I used the entire spindle from
the Nova and modified the control arms to use the larger ball
joints.  These spindles were used on '64-'72 Chevelle, etc,
'67-69 Camaro, etc, and '68-74 Nova, etc.  These spindles are
taller then the Vega spindle and increase the camber gain.
Begining in 1969, single piston sliding calipers were used.  I
also increased the caster angle from -3/4 to +5 by moving the lower
ball joint location forward and making new upper control arms.
The car uses power steering from a '84 Camaro Z-28 (bolt in) and has
a special spool valve.

The rear calipers, rotors and brackets were adapted to a Monza
rear axle.  The axle shafts were redrilled with the 5 on 4 3/4
bolt pattern.  The parking brake levers would interfere with
the inner wheel well so I spaced the calipers and rotors out 1.4
inches each side.  This worked well since the front end is
wider than with the Vega spindles.  I understand that 2wd S-10
axles from '82 or 83 are direct replacements for the Monza axle (7.5
ring gear) to provide the 5 bolt pattern without redrilling.
My cars are '76s so they all use the torque arm and panhard rod rear
suspension. This is as good as it gets for a live axle.

The Corvette wheels are fronts from the 1984 model and are only
8.5 inches wide.  These wheels are offset 1.3 inches and
compensate for the wider front and spaced rear.  I am using
245/45ZR16 tires, smaller than the Corvette size.  They fit
without flares but they are too big.  I recommend 205/50R15
front and 225/50R15 rear on 15x7 rims.  I think 4wd Blazer
wheels should have the correct offset and size.

I recommend the V-6 over the Quad 4.  There have been many
durability problems with the Quad 4: timing belt idler, head gasket,
etc.  Also,  the intake system is all wrong for a rwd
car.  The throttle body would face the rear.  This stuff
could be fixed but it would be a lot of work.  If you can find
a complete Camaro donor car the conversion would be easy.  By
the way, I got all my parts from junk yards and have about $5,000
total invested in the V-6 Vega.  My daily driver is only a
$2500 investment.  I expect to have $3000 or so in the
Cosworth.  These costs are for like-new cars with everything
working and good parts.  A lot of man-hours, though.  I
have already driven my wagon 40,000 miles over the past 3
years.  This is not expensive.  Also insurance is
cheap.  I often tease my wife that her Volvo cost more than all
3 of our other cars put together.

Nice to hear
from you Dean,

The S-10 axle sounds like a good way to
go.  So does the Tec II injection.  The Camaro T-5 mounts
at a 15 degree angle.  A matching Camaro bellhousing will make
it all fit.  I am using a hydraulic throwout bearing from
Tilton to release the clutch.  The cable clutch will not last
long with a V-6, too much friction.

Positraction will definitely make it easier to
loop the car, but you can get more power down before it breaks
away.  Be careful and practice.  Its actually easy to
control if you are aware.  Without posi, you will spend a lot
of time spinning one rear tire.  Don't forget though, with an
open differential, both rear tires always get the same torque.
Its just that when the first one starts to spin, thats all the
torque it can take, and thats all the torque the other rear tire
gets.  With posi, no tire spins until both do.  More
torque goes to the more heavily loaded tire than the less loaded
one.  This creates power understeer until the tires begin to
slip then there is a quick transition to oversteer.

In my opinion, a Torsen differential is best,
followed by a viscous
clutch, then a conventional clutch type
posi.  The Torsen will make the transition from power
understeer to power oversteer much smoother but it will still
happen.  At any rate, with a little practice on wet and empty
parking lot you will have no problem.  My son's 229 with carb
will break the tires loose in the middle of first gear.  Your's
should be faster.

I would recommend a 3.42 axle ratio with a
Camaro V-8 T-5 tranny.  The V-6 versions had a much lower first
gear and wider gaps between the lower gears.  A 2.92 or 2.73
would work with the V-6 tranny.  The V-8 gear ratios are
2.95/2.05/1.40/1.00/0.62.  The V-6 ratios are
4.06/2.40/1.50/1.00/0.84.

The early V-8 trannys, '84-85, had a 0.72 5th gear.  The '90
and later trannys were "World Class" designs with better
synchros.  After '89, the trannys had only the electric speedo
pickup.

The Vega chassis is pretty flexible.  I don't know of
any subframe connectors.  My cars are '76's and are a little
better.  Perhaps you can overlay some sheet metal on the rocker
panels.  The factory ones are pretty small and tuck under the
body.  Nice square ones would stiffen hings up necely.
Look at a Mustang convertible for ideas.  Ford used rocker
panel stiffeners.  Another weak spot is the base of the
windshield pillar.  Welding16 gauge sheet to strengthen the
joint to the door hinge pillar will help a lot.  Also, a cross
body tube beneath the dashboard would help.  I have not done
any of these strengthening modifications to my cars but they will
help.  Also, replacing the bumpers with fiberglass replicas
will save 150 lb and make the car more
responsive.
The front brake pistons are 2
15/16 diameter and have an area of 6.78 square inches.  The
rear pistons are 2 1/16 and have an area of 3.34 square
inches.  The total area is 10.12.  That makes the front
6.78/10.12 and the rear 3.34/10.12.  The front tires are a
little shorter than the rears the overall I am very close to
70/30.  Disc brakes have a linear relationship between line
pressure and brake torque.  Drum brakes do not.  A drum
brake's braking torque increases more than the line pressure because
it is self energizing.  You must use a proportioning valve with
a disc/drum setup.  The latest Blazers have 4 wheel disc
brakes.  Perhaps one of those axles would work for you.

Good luck!
Gary

A V-6 Vega is
nearly the same as a 3/4 scale V-8 Camaro. Thats why I recommended
the V-8 tranny, its gears are well matched for the smaller engine in
a lighter car. The new Camaros have different tranny mounts,
built-in hydraulic clutch slave cylinder, and electric speedo. I
don't know about the V-6 but the new V-8 bellhousing bolts to the
block and oil pan to form a very rigid attachment. At any rate,
there is nothing wrong with using a complete matched engine/tranny
from a Camaro. I don't know
what gears are used in the Camaro
rear axle. If the newest tranny still uses the 4.06 1st gear, I
think a 2.93 or so axle ratio would be good. If the S-10 axle comes
with the 3.42 leave it in. If it has a ratio in the high 2's, I
would leave it alone and save even more money for now.

I
don't know where to get a torsen for an S- 10 rear. Try
Drivelines
Unlimited in Detroit. Check Car Craft or Circle Track
ads.

I think your biggest problem using the '96 Camaro tranny would be
the speedo drive. Vegas of course had a mechanical cable. The Camaro
tranny has a toothed wheel on the output shaft and a pickup coil.
This generates an AC signal to the PCM which in turn operates the
speedo, cruise, etc. There are some aftermarket companies that make
speedo gear conversions for these trannys. Or you could use an
electric speedo. You may need a
conversion box to set the input
to the speedo.

I think you
can make an excellent car with either the 4.3 or the 3800.  The
complete Camaro setup would be more modern but have less
flexibility. Your choice for accessories is reduced with the 3800
and things like engine brackets would be Camaro only
stuff.

You will have difficulty attaching a torque arm
to the S-10 rear.  I would not weld to the cast iron
case.  You could make a bracket  that bolts to the housing
using the cover bolts.  The torque arm could then be a 2x2
rectangular tube that goes foreward under the driveshaft.  This
has the advantage of providing clearance to the floor and allows
dual exhaust on either side of the torqu arm and drive shaft.
The Vega/Monza torque arm was a tall channel similar to the Camaro
arm.  The '76 and later Vega floor pan was modified to clear
it, especially in the area between the rear seats.  I think a
Monza/Camaro style torque arm would hit the floor of your '74.
A torque arm that attaches to the axle bolts would also provide a
center mount for a Watts linkage which is superior to a panhard
rod.

The
Vega/Monza torque arm had a large round rubber bushing at the
front.  It bolted to a bracket that in turn bolted to the
tailshaft of the tranny.  The forward end of the Camaro torque
arm has a tab that slips into a rubber/metal bracket that bolts to
the side of the tailshaft.  You could use a Camaro style
attachment for the Camaro tranny.  Both these methods of
attaching torque arms give less than optimal geometry.  The
vertical reaction of the front of the torque arm is useful in
providing anti-squat. If it is so far foreward the anti-squat is
lost.  If you are fabricating your own torque arm anyway, why
not make it shorter and attach it to a crossmember?  I think a
half length torque arm would work well.  Calculate the
anti-squat to make sure.  Don't do any suspension design by the
seat of your pants.  While were on the subject, nothing says
that the torque arm must be in the middle.  Since axle torque
lifts the passenger side rear tire during acceleration, a torque arm
on the passenger side would counteract this torque and make more
even loading.  It would also counteract the engine
torque.  This type of arm sould be welded to the axle tube and
come down and foreward below the floor pan.  If you're
interested, I could provide more details.

Narrowing a Camaro axle would be expensive.  I
think it would be much easier to get a Monza axle housing and
install the S-10 axles.  The 7.5 inch gear and differential
case are nearly the same as the Camaro and S-10 and should be plenty
strong for a V-6.  The Chevy aftermarket Camaro rear axle uses
a Dana 44 which is really strong and has torsen differentials
available for it.  At some point you may want to put in a
Corvette aluminum rear end.  The track is a bit wide but the
gearcase and attachments will fit.  Its lightweight and
strong.  Choices from the sublime to the
rediculous!

Take a side
view of your car.  Call the point where the rear tire touches
the ground "P".  Draw a line up and foreward at an angle "A" to
the ground.  tanA=h/l where h is the center of gravity height
and l is the wheelbase.  If the foreward mount of the lower
control arm is on this line, the rear suspension has 100% anti
squat.  This means the tendency of the rear axle of the car to
drive under the body and jack up the rear exactly cancels the rear
weight transfer under acceleration.  If it is below, there is
less than 100% (the rear will squat a little).  If it is above
this line, the rear of the car will rise as the car
accelerates.  The h for a Vega is about 20 inches.  The l
is 97 inches.  This is anti squat just for the rear control
arms.

There is also anti squat from the torque reaction of
the rear axlepushing up on the front of the torque arm.  The
force to accelerate the car at the rear tire footprint times h
results in a torque that causes the body to squat.  This same
force times the tire radius is the axle torque.  Divide this
torque by the torque arm length to get the upward force at the front
of the torque arm.  This upward force times the horizontal
distance between the front of the torque arm and the center of
gravity results in a torque on the body that counteracts the
squatting torque.

Lets say the trailing arm location gives 50%
anti squat (this varies with ride height and tire diameter) and the
torque arm gives 25%, there should be a total of 75%
anti-squat.  This is a lot.  Drag racers use 100% or more.
Road racers use 50 to 75%.  The long torque arm used on Camaros
and Monzas anchor to the body in front of the center of gravity and
increase squat, but not by much.  Short torque arms were used
in Chevettes which was an old Opel design from the 60's.  The
Chevette arm is part of the rear axle and is a torque tube.

Running the torque arm below the center
section would limit ground clearance.  It would be better to
route the arm below the driveshaft then around the center section to
the bracket which bolts to the cover holes. Alternately the torque
arm could split near the rear u-joint and weld to the axle tubes, or
as I mentioned before, it only has to be on one side.

Vegas did
come with power steering.  They used the standard GM box.
Some Monzas used a very light duty box.  Don't use that
one.  The steering column is different.  There is a lower
bearing at the firewall and a second joint in the engine compartment
just below the brake cylinder.  You can use a column from a
Monza.  Power steering was common on Monzas but not on Vegas.
Get a steering box from a Z-28 Camaro.  It has much better
valving.  The steering box bolts in place.  The centerlink
is different (shorter on the steering box side).  Monza/Vega is
the same.  '80's Camaros had a different steering box spline
than the Vega/Monza.  Racing U-joints are available or use
Camaro steering column sections to make it fit.  Be sure you
don't defeat the collapsing feature.

The Vega frame rail is
pretty weak and flexes a bit.  Weld it up and add a cross
member in front of the crankshaft pulley to stiffen it up.  A
rack and pinion would be better if you could find one that is built
for high performance (good steering feel).  You could mount it
stiffly and get the bump steer right.  Corvette/Camaro are
great but too wide.  If you shorten the tie rods, make sure the
bump steer is good.  Rack mount height and tie rod length is
important.  With G-body spindles and brakes you should check
bump steer anyway.  The car should toe in as you jack it up and
toe out as you compress the springs.  This way, when you
corner, the wheels will steer out of the turn a little (roll
understeer).  Try to get the bump steer close to zero.

Use a pump that matches the steering
box.  The new pumps are small and have remote reservoirs.
Rack and pinion are high volume low pressure. Recirc ball is low
volume high pressure.  You will have to fab your own
brackets.  The stock location of the pump is low on the block
which interferes with the steering box on a Vega.  Its really a
small car.

A Tremec should be bulletproof behind a V-6.
You'll be ready for a 350 when you grow used to the V-6 (I'm
kidding, please resist this temptation).  I think the Tremec
mounts straight up and a standard bellhousing will work. The Tremecs
I know are for Fords.  Make sure yours has a Chevy bolt
pattern.If its for an '80's Camaro, it would mount at an angle and
require an '80's Camaro bellhousing.  If it fits straight up,
it will fit any Chevy bellhousing from '55 to '92.  I have a
Monza V-8 bellhousing that has cable cluch provisions if you are
interested.  It fits any standard Chevy manual
transmission.  Its in the V-6 car now but I will be changing to
a Camaro T-5 soon.

If you are just putting the S-10 rear end in
the Vega, you must be going to use the stock 4 link
suspension.  Wheel hop city!  Any street 4-link will do a
poor job of holding a live axle.  The torque arm and panhard
rod take the place of the upper links and do a good job.  The
Vega setup was designed to save space and as a result doesn't
control the axle very well.  It is also very soft to stop 4 cyl
vibration from being transmitted into the body.

Those weights on the rear of the upper arms are vibration
dampers.  Replace the lower control arm bushings with urethane
ones.  The uppers need to stay rubber to let the suspension
move.  They're small and stiff anyway.  Raising the rear
mount of the upper link on the axle will shorten the effective
torque arm length and improve anti lift.  There used to be
available cast iron brackets that did this.  If you are having
mounts welded to the S-10 axle, have the uppers made 1 inch
taller.  Check floor and exhaust clearance.

The Main thing

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Every V-6 that I know has even firing within each
bank.  Its the bank tobank firing that is even or odd fire.  A 6
cyl fires on average, once every 120 degrees of crank rotation.  A 90
degree block angle requires a 30 degree crank pin split to achieve 120
degree firing interval.  A 90 degree block without a split crank pin
creates an odd fire engine with 90 -150 -90 -150  cylinder
timing.  A 60 degree block requires a 60 degree crankpin split to get
even firing.  There is no difference in exhaust pulses between a 60
degree block even fire V-6 and a 90 degree block even fire V-6.

It is very efficient to combine all 3 cyls of a V-6 bank into one log
type manifold.  The exhaust events are separated enough to be
independent.  If I remember, you are using the factory exhaust
manifolds.  These are fine.  I don't think you will be able to
fit a 2.5 inch exhaust tube to them.  The outlets probably will fit
only a 2 inch tube.  Dual 2.5 is definitely overkill but there is no
harm done if you can fit the system.  I think you will lose torque if
the manifold pipes are larger than 2 inch, not because of low backpressure
but because the first length of exhaust is part of the tuned system.
You need high velocity just after the manifold (not too high, but 2 inch
is high enough) so the exhaust has some momentum.  Remember, only one
cylinder is using it at a time.  After the crossover, or an expansion
chamber,  there is no tuning anymore so bigger is better if it
fits.

The dual system I had years ago had 1.5 inch pipes.  The OD of the
mufflers was only 2.25 or 2.5.  The OD of a 2.5 inch core muffler has
to be more than 4 inches, pretty big. I don't know about Moroso Spiral
Flow mufflers but I bet they are loud. Borla makes long mufflers with
three tibes inside.  These absorb sound well. Adding the resonator
tips will help.  I would suggest trying to use a factory type muffler
behind the axle.  It will be much easier to fit 2 inch duals than
2.5.  Perhaps dual 2 inch over the axle into a transverse muffler
that has dual inlet and outlet.  Early 70's Camaro and Nova used such
a setup.  Maybe there is a Walker Dynomax muffler for one of those
cars that will work.  The old Z-28 muffler had much better flow than
the standard one and gave a nice gurgle with the V-8.  A V-6 should
be slightly louder.  Go to your friendly local auto parts store and
ask to browse their muffler catalogue.  There is usually lots of
dimensional information in the rear of the book.  Or, ask to walk
through the storage room.  You may see something that would
work.