1974 Challenger Restomod

[anlauto]

I love the seats, they turned out great !

[Dmod1974]

All set and ready for better weather.  I'm going to degrease my engine bay this weekend now that the power steering is finally sorted out,


I put together a How To video on modifying the stock Gen 3 hemi power steering pump pressure and flow rate to be more compatible with the steering (and hydroboost if you're running it.)  Hopefully this saves some of you some time and money for other things!

[Katfish]

Nice work and detailed explanation.
I have the Holley pump with Borgenson gear and I have the hard steering issue at idle, hard turns.
If I'm hearing right, that means too much pressure?

[Dmod1974]

Nice work and detailed explanation.
I have the Holley pump with Borgenson gear and I have the hard steering issue at idle, hard turns.
If I'm hearing right, that means too much pressure?

The Holley pump is a GM Type 2 pump.

If it's only at idle and low/no speed turns, no, you most likely need MORE pressure.  One of 2 things is causing that:

1.  You are hitting relief pressure before hitting the actual locks during normal turning.  If that is the case, the pump will make the same distinct relief whining noise like when you turn the wheels all the way in one direction.  If that is the case, you need a higher relief valve pressure.

2.  You don't have enough flow rate at idle speed.  This one can be harder to resolve.  Changing the flow restrictor fitting MIGHT resolve that if the flow is really cut down, but too much of an increase may cause too much flow rate at higher RPM which leads to twitchy steering.  Without modifying the pump internals, raising the idle speed or changing the pulley ratio may also be required.

[Brads70]

Well done, great video, Thanks for sharing this info!

[Dmod1974]

I haven't posted in a minute since I've been busy driving and breaking this car in since March 1st opened up and my antique plates were road legal again.  Even dodging crappy weather and waiting for rain to wash away the salt several times, I have 150 miles on it already.

It drives great!  No squeaks or rattles, and so far the only leak I had was from a brand new and defective AN hose end on my Schwartz supercharger coolant crossover manifold kit.  Go figure.  Luckily, I was able to get the only one out and the new fabbed hose in without removing either block which would have required blower removal.  It's maiden voyage was on 3/1 after work so it was dark out (I couldn't wait!), but the 17w Dapper Lighting LED's lights worked GREAT.  I was a little worried (after I bought them of course) that I should have went with the 30w bulbs, but it ended up being a nonissue.  The 17w bulbs lit the road as good as my modern cars with LED lights without being overpowered.

Zero issues with the low/high speed steering and brake feel, so the pump mods worked well.  The brake proportioning is dialed in, but I'm still working on getting the coilover firmness where I want it.  I think I need to firm up the front end a fair amount more to match my much stiffer springs that I installed after dropping the Hellcrate engine in.  The rear is about where I want it.

I'm really surprised how quiet the 3" exhaust is.  There's no drone which is a good thing, but I swear it is quieter than my old 2.5" setup.  I'm hoping that's just because it's insulated so well; it's been too cold to cruise with the windows down yet so I guess we'll see.

The HC engine/6 speed combo w/ 3.91's is a blast to drive.  Around town it is very mild mannered, and at cruise RPM the double overdrive gears make it super comfy to drive for long periods of time.  The shift throws aren't too short or long, and the hydraulic clutch effort is just right too.  It's much firmer than many late model cars where you can push the pedal down with your pinky, which I prefer since you have more feel during initial engagement.

I did have to get creative to get the Dakota Digital RTX speedo, SST Reverse Lockout Module, and Mopar Performance CANBUS Interface Device (CBID) to all see VSS inputs correctly so everything would work, but I knew I'd probably have to do that initially so I made sure the wiring was accessible. 

The Reverse Lockout Module allows reverse to be selected at very low speeds (varies based on VSS pulses on a given combo - for me, it allows reverse at roughly 3MPH), and disables it above them.  Unplugging it isn't an option unless you want to gorilla it into reverse which could damage things over time, and powering it at all times is a problem since it's VERY easy to hit REV instead of 5th.  Some people will just wire the trans mounted solenoid to receive power from the brake pedal, but that's kind of tedious too.  The CBID somehow uses GPS AND the VSS signal to initially calibrate and then derive the actual vehicle speed to send to the PCM.  On this engine, it's used for some idle and engine torque mode algorithms.  Not everybody uses it, but you can have some idle and drivability issues without it as well as a CEL that won't clear (U1110 code).

The blower wine under load is music to the ears!  WOT is something else though; I need to learn how to control this car since it is by far the fastest thing I've ever owned.  Even at part throttle in 3rd gear with 305 drag radials out back I had no issue spinning the tires unexpectedly at 50MPH.  The torque this engine makes down low is wild.  I need to get it to the track to get myself comfortable and see what it can really do.  I'm sure the 8 3/4" is on borrowed time, so it'll eventually get a 9" w/ inboard mounts with a numerically lower number ratio and even wider tires to make full use of that power.

I just had paint correction and a ceramic coating applied to it to protect the fresh paint as much as possible.  I can't wait to rack up some more miles and really start beating on this car!

[anlauto]

Without having to go back and read the entire thread, I have a question regarding fitment of the hellcat motor in an E Body on RMS front suspension. I've done a couple of 392's now, but just sold my first build with a Hellcat. The 392's are tight at the firewall.

How is the clearance of the supercharger at the firewall, and did you ask RMS to move it forward at all ?

[Dmod1974]

Time is money, eh?  Do I get any commission for doing the engineering legwork?!   

It's extremely tight, even with an aftermarket crossover you may have issues with the wiper motor clearance in particular.  The blower sucks up a lot of space back there.

My original order from them was back when I had a 408 stroker, so I cut off the original brackets, ballparked from references where RMS sets them, did mock up with them moved a little more forward since I knew it was going to be a problem, and welded on the Hellcat mounts myself.  I didn't want to get too crazy though since my car is stick and the shifter to opening clearance would become a problem next.

That said, I can't comment 100% on the fitment from RMS as delivered with Gen 3 hemi mounts welded on by them.  I'd bet just from car to car variation some will barely clear, and others won't.  It's that tight.  A lot of people who have done this swap on early Mopars have run into wiper motor clearance issues.  I'd move them forward to be safe and avoid a really bad situation after the car is in paint, etc....

[anlauto]

Time is money, eh?  Do I get any commission for doing the engineering legwork?!   

When I ordered it from RMS I was asking Bill and he said nonchalantly, I can move it forward 1" if you like ?   and I'm like, does it have to move forward, what have you done in the past....and he wasn't really clear, said he hasn't had to before ??

So I opted to just get the mounts made in their standard position...was thinking after, that I could simply move the engine forward, by just re-drilling the four holes on the mount plates , the tranny cross-member is slotted likely only need 1/2'' or 3/4''

I'm using a 3spd wiper motor if that makes a difference.

[Dmod1974]

Time is money, eh?  Do I get any commission for doing the engineering legwork?!   

When I ordered it from RMS I was asking Bill and he said nonchalantly, I can move it forward 1" if you like ?   and I'm like, does it have to move forward, what have you done in the past....and he wasn't really clear, said he hasn't had to before ??

So I opted to just get the mounts made in their standard position...was thinking after, that I could simply move the engine forward, by just re-drilling the four holes on the mount plates , the tranny cross-member is slotted likely only need 1/2'' or 3/4''

I'm using a 3spd wiper motor if that makes a difference.

Maybe....  I don't think there is enough room on the motor mount plates to safely slot or redrill them 1/2" to 3/4" forward.  Might not be an issue with a 5.7 or 6.4, but 717HP in a stick car is going to stress things a lot more.  You'd be awful close to the ends of the plates the way they are contoured.  Either way, I guess you'll find out soon enough if you need to do that at all, and if it'll work.

I'm running a 3 speed too; I'm not sure if it's any better or worse but that is without a doubt the closest interference point.

[anlauto]

I was already thinking of having to extend the plate on the front end of course

[Katfish]

Car looks awesome, glad to hear it drives as good as it looks.
I too was surprised by how docile my 5.7 sounds compared to the 340 it replaced.

[Dmod1974]

Car looks awesome, glad to hear it drives as good as it looks.
I too was surprised by how docile my 5.7 sounds compared to the 340 it replaced.

Thank you!

Yeah, I'm really glad I didn't install resonators under the trunk floor when I built the exhaust.  It would have been way too quiet for my liking.  I always have the dump pipes for track days I suppose.  I would like to swap in a max effort Hellcat cam and limiter kit one day too.  MMX sells one that sounds fricking amazing.