Tav 1970 Road Runner RM23N0G217270

[6bblgt]

the ground strap on the back of the engine is a '69 "thing", was there one there on the '70 when you took it apart?

[cataclysm80]

Still May 2017

I had to learn a bit about B body disc brakes, so here's a bunch of useful brake info.
Some of this also applies to E bodies.  Since this is an E body group, the last picture here is an E body diagram.

I ordered an MBM Brakes master cylinder and booster kit from Mancini Racing.  This includes the master cylinder, brake booster, firewall reinforcement plate, and linkages to the pedal.  These are all parts that are needed to convert from drum brakes to disc brakes.
Item MBMBCK8536-1  &  MBMBCK8536-2  appear very similar in the photograph and item list, and it took me a bit to figure out which item number was correct for my application.
The item fitment description lists the wrong change over year for B bodies, and that added to the confusion.  It says that 70 B bodies are the same as 70-74 E & 71-74 B, but this is incorrect.  70 B body is actually like the older 66-70 cars.  B body didn't update until 1971.
The difference between these two items is the firewall reinforcement plate. MBMBCK8536-1 comes with the 1966-1970 B body firewall plate, while MBMBCK8536-2 comes with a 1970-1974 E body & 1971-1974 B body firewall plate.
I'm building a 1970 B body here, so I bought the MBMBCK8536-1, which strongly resembles what the factory would have used in a power disc brake car.
The photo provided for MBMBCK8536-2 does not resemble what the factory used in E bodies, so I would be reluctant to use that in an E body.  (maybe the picture is wrong?)

[cataclysm80]

the ground strap on the back of the engine is a '69 "thing", was there one there on the '70 when you took it apart?

I just checked various old pictures, and the answer is no.  This car originally had a dimple in that location, but it hadn't been drilled for anything.
Would this ground wire also have been used on '68's?
I did deviate from original on a few different things on this car, so I don't mind having an extra ground strap.  (though I wouldn't have installed it if I'd realized)

Thanks for pointing it out!  That may be helpful to other people reading this thread in the future.
If anyone else sees something incorrect, don't be afraid to say something.  I don't mind.

I should probably mention that the non-air conditioning firewall from AMD has one hole drilled for mounting an air conditioning box.
Pay attention so that you can weld that hole up before painting the car.

[6bblgt]

yes, the '69 & earlier had a ground from the back of the engine to the firewall - in '70 they added the ground from the negative battery cable to the core support

[cataclysm80]

May 2017 Again

Time to figure out the stereo. 

First I did some research into what was originally available for B body radios.
This info may not be as complete / thorough as my E body radio post  https://forum.e-bodies.org/reference-material/18/radio-options-r11-r22-r26-r31-r32-r33-r35-r36/348/
It's a good starting point for anyone looking for info though, and maybe it will help point someone in the right direction.

B Body Radio Options 1968-1970 & 1971-1974

In 68-70 B bodies Only the AM 8-track cars had a 3 speaker dash (with crossover box and harness)
The AM 8-track was the only Stereo radio available.  AM & AM/FM radios in 68-70 B bodies were Mono.
Some 68-70 cars have package trays with symmetrical speaker holes, while most have asymmetrical speaker holes.  The difference was do to different vendors supplying the part.
68-70 R31 is the rear speaker option.
68-70 never had dual rear speakers, they had an optional single rear speaker. 
That rear speaker is a 5 x 7 speaker on the drivers side. 
The passenger side hole was only used for an optional defogger. 
The defogger was designed to fit in 6 x 9 speaker holes, so that is why the 68-70 B body defogger intake opening looks like a 6 x 9 speaker hole.
Since dual rear speakers were not available, these cars never had an adapter for dual speakers with defogger.
In 68 the rear speaker fader was next to the radio in the faceplate.
in 69 & 70 the rear speaker fader was on the bottom of the dash frame, to the left of the ashtray.
Stereo radios with a rear speaker used a dual pot fader, while mono radios with a rear speaker used a single pot fader.   



71-74 B bodies never had a 3 speaker dash, not even on cars with a Stereo radio.  Instead, a Stereo radio came with a single dash speaker and a drivers rear speaker.

71-72 B bodies could have...
mono AM single dash speaker
mono AM single dash speaker + drivers rear speaker
mono AM single dash speaker with cassette player (only 71-72, not a listed option in 73-74)
mono AM single dash speaker with cassette player + drivers rear speaker (only 71-72, not a listed option in 73-74)
Stereo AM/FM single dash speaker + drivers rear speaker
Stereo AM/FM single dash speaker with cassette player + drivers rear speaker
A Microphone is listed as being optional only with cassette players, and only for 1971. (likely available over the counter for other years)
Defogger was optional and used the passenger side package tray hole as an intake, same as in previous years.
The package tray is missing a provision for mounting the dual speaker with defogger adapter, these cars never had an adapter for dual speakers with defogger.

73-74 B bodies could have...
mono AM single dash speaker
mono AM single dash speaker + drivers rear speaker
mono AM/FM single dash speaker (new for 73-74)
mono AM/FM single dash speaker + drivers rear speaker (new for 73-74)
Stereo AM/FM single dash speaker + drivers rear speaker
Stereo AM/FM single dash speaker with cassette player + drivers rear speaker (only 71-73, not a listed option in 74)
Defogger was optional and used the passenger side package tray hole as an intake, same as in previous years.
The package tray is missing a provision for mounting the dual speaker with defogger adapter, these cars never had an adapter for dual speakers with defogger.


The adapter for dual speakers with a defogger was only used on E bodies & C bodies.  (same part on both cars)


Original speakers were 8 ohm
You never want to run 4 ohm total impedance speakers with these old original radios. It will burn up the radios output transformer over time.

Modern aftermarket radios are designed to handle modern 4 ohm speakers.  (you could use 8 ohm speakers with a modern radio, but it would be quiet)

The new reproduction B body radios have modern internals and can handle 4 or 8 ohm speakers.

Turnswitch.com has an excellent selection of 4 ohm & 8 ohm speakers that are designed to fit classic cars without cutting your car or dash.  They accomplish this by using smaller super magnets like inside computers, instead of using larger less powerful ceramic magnets that are typically found on aftermarket speakers.

Having original speakers reconed isn't a great option if you plan to actually listen to the radio because the old magnet will never be as good as it used to be.



I decided to use a Retro Radio power antenna, which I modified a bit.  Details on that can be found here.
https://forum.e-bodies.org/electrical-and-audio/11/power-antenna-using-original-antenna-bezel/3609/msg52748#new

Though this car was originally a Stereo 8-track car with the 3 speaker dash, I decided to go with a reproduction 1970 AM/FM with all modern internals.  It has Bluetooth and an auxiliary input on the back for my MP3 player. 
The 1970 AM/FM B body radio is a very desirable one year only radio, and I'll be glad to use my 3 speaker dash with the modern internals.
Antique Automobile Radio is the manufacturer.  http://www.radiosforoldcars.com/whoF.htm

For Speakers, I went to Turnswitch.com and ordered a pair of the 3.5 inch square 8 ohm speakers for the stereo dash locations, and a 4x10 Mopar B body Stereo High Output 8 ohm for the dash center (it's a bracket that holds two 8 ohm round speakers in the original 4x10 location, without interfering with any of the heater cables under the dash).
This gives me four 8 ohm dash speakers, that I've wired in parallel so that the left pair is a 4 ohm load, and the right pair is a 4 ohm load.  The reproduction radio has modern internals which can handle a 4 ohm load, so this should sound great! 
The 3.5 inch square outboard speakers need a bass blocker installed in line with the speaker wire so that they don't distort from low bass notes.  The center dash speakers can handle the low notes and don't need the bass blockers.
I also ordered a pair of the SX69 coaxial 6x9 oval speakers, which will mount under the package tray just fine without any cutting or drilling.

Wiring Diagram pictured below.

[cataclysm80]

The wiring grommet that comes with the power antenna fits the factory hole in the kick panel sheet metal.
The top of the power antenna is held by the fender.
A metal bracket was made to hold the bottom of the power antenna.  It goes over these two door hinge bolts that are sticking out, and then I put nuts on them to hold the bracket in place.  (hinge bolts marked with red arrows in pic below. Not my car in this pic, just grabbed this off the internet to show the door hinge bolts) The metal bracket goes forward from these hinge bolts, and down to the bottom of the antenna, where it bends horizontal to fasten to the bottom of the antenna.

Next the bracket was painted Plum Crazy to match the car, and everything was installed.

[cataclysm80]

July 2017

Suspension

Rebuilt the 8.75 rear end with 3.55:1 gears and a Sure Grip.

B body & E body suspensions are extremely similar.  I'd like to do a more detailed suspension write up in the future, but for now, here's the short version.

With the car all taken apart, I wasn't able to weigh the car for use in the suspension calculations, so I had to do a little educated guesswork.
A friend weighed a 1970 Hemi GTX, and that gave me something to guess in the ballpark with.  It weighed 3841 pounds without a driver, 2177 on the front wheels = 54%, and 1845 on the rear wheels = 46%.
I looked up engine weights, and came up with 765 pounds for a Hemi, and 620 pounds for a 383, so I'm guessing about 145 pounds off the front weight of my 70 Road Runner.
With a 181 pound driver, I'm guessing the 70 Road Runner should weigh about 3877 pounds.  I'm guessing 2094 on the front wheels = 54%, and 1783 on the rear wheels = 46%.
OK, now I have an educated guess at what the car should weigh.  Ideally, you'd just weigh the car.

I wanted improved handling, so stock torsion bars are to soft for my tastes, but at the same time, this isn't a race car that's going to be driven on a perfectly smooth track.  This will be a fun street driven car.  I was aiming for torsion bars that were stiff enough to have a spring rate of about 10% of the front end weight, without going over 10%.  I selected Firm Feel 1.00 inch diameter torsion bars, which have a spring rate that is 8.9% of my estimated front end weight.
I wanted to match that 8.9% figure for the spring rate of the leaf springs supporting the rear weight.  The math said that I needed 160 pound spring rate (each) leaf springs to accomplish this. 
I've heard that the Mopar Performance Super Stock springs are 160 pound spring rate, but I've also heard that they're intended to be race parts, so they don't have the durability of a part designed for long term street use, and they sag after a few years.  They also require different spring mounts because they're not the same length as original springs, and that also affects the way they function.
I decided to have Firm Feel custom make leaf springs for me.  They're original length to use the stock spring mounts, the spring rate I specified, and should be durable enough for long term use on the street.  I don't plan to replace my leaf springs every 3 years like some race cars might.

The stock front sway bar is better than nothing, but simply isn't large enough diameter.  I chose a Firm Feel 1.125 diameter front sway bar.
Doing the math, this gave me a front roll bias of 78%, which according to the theoretical handling line, would be perfect for a car with 54.5% of the total car weight on the front wheels.
If my car weight is actually 54% on the front like I guessed, then I'll be just a little bit on the oversteer side of the line (the less safe side).  Since the car weight was guesswork though, I'm going to start with this and check the actual car weight when it's finally all put together.
If I end up with 54.5% to 55.5% of my total car weight on the front wheels, then I'll run this setup as is.
If I end up with 53% to 54% of my total car weight on the front wheels, then I'll change to a Firm Feel 1.25 diameter front sway bar.
If I end up with 56% to 57% of my total car weight on the front wheels, then I'll add a Firm Feel .75 diameter rear sway bar.
Rear sway bars were never originally available on these cars, but Firm Feel does make them.
These figures will keep me close to the theoretical handling line, or just on the safer understeer side of the line.


I'm running Firm Feel tubular upper control arms with offset bushings installed for more caster.  This car will have plenty of caster adjustment available.  I'm aiming for 6 degrees positive caster and negative .6 degree camber.
I think the Hotchkiss tubular upper control arms are the best performing upper control arms for a Mopar, but the pivot relocation which gives them an advantage also creates additional effort during alignments, and I didn't want to hassle with that.  (plus they're very expensive)
I haven't tried the Magnum Force tubular upper control arms, but I've heard good things about them, including that they provide +4 degrees of caster instead of the +3 you get from Firm Feel.  I would seriously consider using those on a future build, without the problem solver bushings, and you might still be able to hit +5 degrees caster if you're lucky, which is pretty good. 

I'm running Bilstein shocks.

I've welded plates to the bottom of the lower control arms to keep their U shape from flexing during hard cornering.

I've also installed Firm Feels idler arm roller bearings, and steering box sector shaft support, to help prevent the K frame from flexing due to the steering forces.

I want this car to still look very original, so I've kept that in mind while choosing these modifications.  Extremely few people will notice torsion bar diameter or sway bar diameter, or that the leaf springs are very slightly different.  Tubular upper control arms aren't really noticeable unless your looking up from underneath the car.
Continuing with this original appearing theme, the car will ride on 15 inch rallye wheels.  I didn't want to go with a larger than original wheel on this car.  I am using modern steel belted radial tires though, and all the wheel lugs are right hand threaded.

The biggest disc brakes that will fit inside the 15 inch rallyes is 11.75 inch rotors.  Consider it done.
11 inch drums on the back.

[Cuda Cody]

Everything you do is done so well!   There is nothing that is overlooked or not thoughts about.  Keep up the great work. 

[cataclysm80]

July 2017

The car is finally on the ground again, followed by installing the headliner.

[cataclysm80]

July 2017

Installing various parts, and all the under dash stuff.
Note the Heater Box Factory OK inspection tag.  A little over 10 years ago, I was able to speak with Frank, who happened to be one of the Chrysler quality control inspectors back when these cars were built.  His job every day was to inspect heater boxes.  They came in on pallets, and he was supposed to inspect a certain percent of the boxes on every pallet.  He had a pile of these green tags, and a ball point pen to write on them.  He didn't always sign the tag.  If the box got a tag, that means it was checked.  Only heater boxes that were inspected received the green tag, so not every car has one of these.

[cataclysm80]

July 2017

The Dash

[cataclysm80]

July 2017

Dash Install
sitting on the side bolts and held in place at the center by a metal wire with a hook bent on each end, so that everything can be plugged in and hooked up.  Then just remove the wire, tilt the dash up into place, and install the fasteners.

[Cuda Cody]

The attention to the details is impressive!   

[cataclysm80]

July 2017

Engine Bay & Engine Install
That distributor is just there to plug the hole in the engine.  I used a different distributer with a tan cap.
The exhaust manifolds were coated in Cast Blast before being painted orange.  When the orange burns off the manifolds, the cast blast grey will still be there to protect them from rusting.

[cataclysm80]

July 2017

A few more pics of some of the suspension items that I mentioned earlier.
I probably should have duplicated the original cosmoline look on the lower control arms.  Oh well.