|
Boss
Frog Kit information...
1.
How much cutting and welding is required? The gussets
at the rear of the engine compartment must be removed, but
this can easily be done with a reciprocating saw. No other
cutting of the tunnel is required, so the dashboard will not
need to be removed. Stock control arms, shocks and springs,
hood, etc can all be reused without modification. There are
several holes that get drilled for frame rails and other mount
points. The NA’s require 4 small tabs to be welded onto
the rear subframe assembly (to match the NB setup). However,
the NA Miata’s rear subframe can be removed with about
6 bolts, and the welding can be done separate from the car
(or at a welding shop).
2.
What steering changes are required? The lower steering
knuckle is replaced with a slightly longer version, which
moves the steering rack forward about an inch. The stock steering
cylinder is behind the center of the front wheels, so the
true effect of moving the cylinder forward should make absolutely
no difference to steering feel or bump steer, and does not
add any additional joints or increase the joint angles.
3.
Why did BF choose the 8.8 differential? BF considered
both the 7.5 and 8.8 Ford differentials, and a variety of
other IRS setups including the Getrag/Cadillac and Supra.
The Getrag was eliminated from consideration because of the
lower torque rating, limited choices of gears and posi combinations,
and it’s recall and failure history. The Supra rear ends
are too hard to find. The 7.5 differential would be a good
choice, but the supply of these is also limited. BF chose
to use the bulletproof 8.8 center section and developed a
unique mounting system to maximize both the strength and ground
clearance. The stock 8.8 outer CV will not clear the shocks,
so remanufactured half shaft assemblies are used with the
Ford 7.5 CV’s and a new custom length 4340 shaft. Our
new half shafts have a short outer boot to clear the shocks.
This rear end arrangement offers a higher overall torque capacity
than either a Getrag or a Ford 7.5 differential system can
deliver.
4.
Why are new rear hubs needed? New OE Mazda hubs are custom
broached to fit the larger outer CV’s, and new wheel
bearings are also supplied with the kit.
5.
Is weight and balance affected? Yes, but not very much.
The engine subframe is about the same weight as stock, and
the engine is only a little heavier than the 4-cylinder. The
transmission and rear differential are both heavier than stock,
so some of the extra weight is shifted rearward again. Then
net result is a shift of a few percent toward the front –
not enough to make a huge difference in handling.
6.
Is power steering available? BF recommends eliminating
the power steering system, but it is possible to keep it.
Some re-plumbing will likely be required as the stock lines
may interfere with the engine subframe. There is currently
no plumbing kit available for these modifications.
7.
Is air conditioning available? BF does not currently offer
a kit to enable the AC system, but it is fairly easy to add,
and there are other sources that do offer a retrofit kit.
8.
Do your kits fir both NA/NB steering cylinders? BF kits
currently are made for the NB steering cylinder. NA steering
cylinder kits are coming soon.
9.
What about front sway bar clearance? The stock front sway
bar would run through the balancer pulley, so it must be shifted
forward a couple inches. The engine subframe kits include
relocation brackets to move the sway bar forward. The stock
sway bar can be used, but the arms should be lengthened about
2” on each side. BF supplies brackets to extend the Racing
Beat aftermarket sway bars to the stock (or aftermarket) end
links.
10.
What about shock, spring, brake, and wheel clearances?
BF recommends using either stock shocks or a performance shock
that will allow up to stock heights, depending on how much
ground clearance you want. Big brake kits work fine. Wheels
and tires up to 16x8 and 245/35-16 will fit without modification.
11.
What about ground clearance? Ground clearance depends
on many things, including exhaust height, shocks and springs,
etc. The BF system will keep everything at or above the scrub
line – the rest is up to you.
12.
Any wheel hop issues? BF supplies new Energy Suspension
bushings in the nose of the differential and heavy urethane
bushings in the rear to help reduce any tendency to wheel
hop. Differential braces are also supplied to tie the rear
subframe into the floor and main frame.
13.
What about a radiator? The stock radiator is too small
to cool the big V8’s, so a new one is needed. A wide
variety of choices exist, including Miata racing radiators
and custom made radiators. BF does not current offer a “bolt
in” radiator…yet.
14.
Shifter location? The T56 shifter will fit right in the
Miata’s body hole, slightly forward of center, but without
any modification to the body or boot.
Have
any questions about parts, kits, or products available from
Bishop are welcome. Contact the us by phone and leave a message
at 604-984-3673 or e-mail by visiting our contact page and
we will respond promptly. Our office hours are Monday to Friday
from 10:00am to 4:00pm PST. We really love to share the fun
with other performance enthusiasts who want to take their
cars to the next level of performance, appearance and handling!
Thanks for visiting!
Complete suppliers of automotive superchargers,
custom, racing and performance parts!
Home
| Contact | Back
| Top
|
BOSS
FROG V8 MIATA KITS FAQ
