Tremec 5 speed swap into a '70 Charger

[XH29N0G]

  I mostly run at 65 (and up 70) but not a lot more on the regular. Our traffic moves a little faster where I am.

 
IMO muscle car guys tend to be unrealistic about modern traffic.  On many interstates the normal cruising speed is 75-80 mph.  

So Mike is right about some of us older muscle car drivers.  

I just thought I would pass along the idea that the lower limit for a gear also can come into play.  For me, my engine lugs if I run it much below 2K so the comfortable speeds for 5th with the 0.64 Tremec gearing are 50-65 (70) with the 4.30.  If I had 3.91 it would be 55 and the same up to almost 80.  This would also be be nice and I have thought about the change.  If I went with 3.55 or 3.23, I would need to be in 4th on the 55 stretches that are around me so the engine didn't lug and then 5th would be fine once I got out of the city.  It would be fine in 4th, but I would need to remember that. If I lived in the middle US with higher limits, I would probably move to something like 3.55 or 3.91.  For me 4.30 seems fine.  None of this is an issue for an engine that doesn't lug.  The downside is I am out of 1st by 35 and out of second by 55-60 when on it.  

I mentioned the 4.30 vs 3.91 because KD mentioned gearing and I thought if that were in play and I were doing it, I would like to make the closest guess to my driving style and likely driving conditions for the engine I had.  He knows his engine and suspension.

A downside of the 4.30 is the driveshaft spins quickly and I had to spend a fair amount of time aligning the driveline angles and get a decent shop for the balance (an operation that works on large trucks) to get it right.  


INTMD8 - It should have been easy enough to figure out, even realize at the time.   But Mike DC just pointed that I'm an old unrealistic muscle car driver (not a racer).  I only happened to figure it out because I was thinking about it on the way to work and then did the calculation.  I kept wondering why my speed dropped, but then I realized I had set the limiter to be safe.  I'm not shifting to 5th and with my tire size, my speed looks like it matches pretty well where my limiter was set it.  I just need to make it back to verify.  

[Just 6T9 CHGR]

Nice write up and that kit seems fantastic & complete.   What are you doing about the pilot bushing in the crank though?   I considered doing a 4-speed swap at one point but was unsure about the crank in my 440...I do not think its drilled for the pilot bushing?

[Kern Dog]

I have an aftermarket crank, a 4.15 stroke Eagle as part of a rotating assembly from Hensley Performance.

[Mike DC]

So Mike is right about some of us older muscle car drivers.  

We have to be stuck in the past, we love 50yo cars!  

But seriously, I think the situation has changed just since overdrive gears became popular in the last 20 years.  In the 1990s you could go 65 and keep up with traffic in most places.  Now that requires at least 70 if not 75.  In open rural areas even soccer moms in minivans are hitting 80 mph.


It makes sense when you realize that the soccer mom's minivan outperforms our classics in almost every way.  Handling, aero, braking, crash safety, quiet interior noise . . . going 75-80 mph in a modern car feels more like 65 mph in old cars.  


I was flinging around a 2015-ish Toyota Camry rental on a windy road a few years ago.  Damn.  I would be proud to have a pro-touring classic car that good.  19" wheels, big brakes, surprisingly hot acceleration & crisp shifting, tight steering, good front/rear balance . . . and that was a friggin 4dr Toyota rental car.  We all know the modern Challenger Hellcats & Camaro Z28s will blow your face off, but even the mundane vehicles are really impressive now.  

[cbrestorations]

  mo gears is mo Bettas...that's why heavier modern cars have such good acceleration is short split between gears...all 8 of them

[OzCharger69]

Great write-up Kern and I'm following this very closely since I will eventually head down the same road too. I was wondering if the auto console woodgrain bit could be cut and modified to suit the manual stick outlet?

[Kern Dog]

Great write-up Kern and I'm following this very closely since I will eventually head down the same road too. I was wondering if the auto console woodgrain bit could be cut and modified to suit the manual stick outlet?

A guy on the 1970ChargerRegistry site did this:

[Kern Dog]

I plan to do the same with mine. I'd like to put a recess in the plate forward of the shifter opening, something big enough to put the cell phone in while charging. Also, the USB port/cable can connect with the stereo to play music or charge the phone.

[Mopar Nut]

Nice write up Greg.

[WHITE AND RED 69]

Car is looking great! Gonna be a nice setup once installed.

Just curious, why did you remove the gear vendors? I have been debating getting one for a while so just want to hear what you disliked about it.

[Kern Dog]

Thanks!

The Gear Vendors unit I had was a first generation model.
It had no mount for the floor shifter so a bracket had to be made. It resulted in the vertical shift rod being out of whack and the shifter felt vague. The shift detents were messed up too. Either I was able to lock it in to Park but NOT get 1st or I could get 1st and it would slip out of Park.
The output of the GV was a yoke requiring a custom driveshaft like you'd see on the front of a 4wd truck. It was fine at low speeds but vibrated the faster I went.
It upshifted fine but would often stay stuck in OD and not disengage unless I shut the car off. This meant when I was at freeway speeds with the 3.91 OD and .78 OD, (Final drive of 3.05) When slowing to a stop, it stayed as a 3.05 gear making it sluggish from low speeds. If I wanted a 3.05 axle gear all the time, I would have just used a 2.94 diff.
The speedometer drive is at a strange angle. Looking from the rear, it is at a 10:30 angle...Pointing to the left and UP. This put the speedo cable in a constant bind since even with the floor dented for some clearance, it wasn't enough. 90 degree adapters are the fix but the tightwads at Gear Vendors refused to sell them, claiming they only produced them to be included with new units sold.
I have been told that the 2nd generation GV units addressed the shortcomings.

[Kern Dog]

I have such a hard time getting motivated in the Winter. It is the worst time of the year for me...I feel like hibernating until Spring.
I did get off of my ass today though.
Seats are out, console too.

[Kern Dog]

Years ago, I made a few wiring changes to the car including a trunk mounted battery and an aftermarket instrument cluster. I used an oval plug in the firewall to pass the wires through. I never thought I'd need the hole since it was for the......Clutch pushrod!
Now I had to find another way through the firewall.

[Kern Dog]

I looked and found a hole just below the bulkhead plug. It was used to mount the original heater and A/C box but since I changed to the Classic Auto Air system in 2019. This hole is right near the starter relay. That is a good thing since 2 of the wires attach to the relay anyway. The remaining wires were for the tach, water temp and oil pressure.
I hogged out the hole and used a 1 " body plug, then ran the wires through that.

[Kern Dog]

Now the clutch pushrod hole is wide open and ready!

[Kern Dog]

I only had a couple of hours to spare today but I did get a few things done.
I removed the external transmission cooler.

[Kern Dog]

I have been trying to do things that require the car to be on the ground before I lift the car up to do all the stuff underneath. I figured that now would be a good time to swap the pedals.
The instructions were quite good here. The fresh air vent comes out since the clutch and brake pedal arrangement uses a longer mounting pin that cannot be installed with the vent in place.

[Kern Dog]

The new reproduction pedals look great. The brake uses the traditional nylon bushings but the clutch uses a trick roller bearing...

[Kern Dog]

The pedals fit in nicely. The manual setups use a longer pin to allow the clutch to ride on. To support the left side of the longer pin, the factory used a bracket like this reproduction.

[Kern Dog]

The bracket bolts to the firewall. Automatic cars are not drilled for this but there are dimples in the metal where the holes need to be. This bracket fit nicely but I did have to take a round file to the hole to get the pin to slide through. I opened it up by about 1/8" , not a big deal.

[Kern Dog]

The pedals are in place and the brake pedal pushrod is attached. I may install the clutch master cylinder and pushrod next, not sure.

[Kern Dog]

Backing UP a little bit...
From about 2012 to around 2014, I tried a few things to improve the braking performance. The car has had 1975 Dart Power front discs since 2001 and I swapped in Dr Diff rear discs in 2006. In 2012, even though the brakes felt decent,  I wanted to shed some weight so I tried switching to a manual master cylinder. I tried 4 of them with bore sizes between 15/16: and 1 1/8" and they all were terrible. The best of the 4 was an aluminum Dr Diff 15/16" unit but even then, it barely would skid on a dirt road. I gave up and put the power stuff back on. Later I saw that I had a disc/drum proportioning valve in the system. 4 wheel drum and 4 wheel disc systems do not use proportioning valves.
I had the prop valve with the power booster in place though....Maybe the power assist masked the mistake enough?
Regardless....I changed to a drum/drum distribution block and braking improved. Awhile later I tried another thing. I took a stock brake pedal and drilled the pushrod mounting hole above the stock hole to gain some pedal leverage. This helped quite a bit. The brakes grabbed sooner and pedal effort went down a bit. It has been this way since around 2014 or so.
Now with these new pedals, the brake pushrod hole is back to the stock position. The pedal sits a little closer to the floor. I want to have the clutch and brake pedals rest at the same height. A slight mismatch is okay but the closer, the better. I don't know how much travel the clutch pedal needs to function. This is a hydraulic clutch arrangement and I have heard that they don't move very far. As stated, the brake pedal is closer to the floor than before. Hopefully the clutch pedal will have enough travel as is. If the clutch pedal has to sit higher, I'll need to lengthen the brake pedal pushrod to allow the pedal to sit higher.

[Kern Dog]

Also....The instructions mention a clutch pedal pad, I'm guessing it refers to something that stops the pedal from moving away from the firewall too far. There wasn't anything like that in the kit. I can make something but it would be nice to know what a stock one looks like.

[Kern Dog]

Looks like I need one of THESE:



https://www.classicindustries.com/product/1970/dodge/charger/parts/md2526.html

[Bob]

Nice work KD.