Modern Transmission in Old Car

[tparker]

I'm built my car with a stroked 340 and can't wait to get it on the road.  One concern is that I will be passed by every car on the freeway. LOL. OK maybe it won't be that bad but it would be nice to have extra gears. I was thinking about the gearvender drive thingy but those arn't cheap, and easy to get due to being backorderd. I have seen several Challengers with modern hemis and drive trains. I don't want to upgrade anything cause I like old school..... but I was currious what it would take to bolt up a modern auto tranny. APparently there are 4 or so different ones, two of which seem like a potential candidate. The few things I read was older so not sure what the current state of things are. Is this something that is reasonably doable? Some people said it was a bolt on thing with some Holley parts, others said it requires major surgery. Thoughts?

By the way, I was thinking of the new challenger trannys vs the 90's Dakota trannys. Though I was thinking of that before I started thinking about this path.

thoughts?

[Deezel]

Tagging in.

I just looked at every option I could find to upgrade to a modern transmission, without hacking up my tunnel, and am pretty confident I'll be ordering an A41 from Silver Sport for my Cuda build. Pricy, yes but it ticks every box on what I was looking for. I looked at Gear Vendors and a 46RH (A518) but to me, they just didn't offer what the A41 does. I don't think there are any offerings from anyone else on such a comprehensive kit like SST provides but I could be wrong.

[7212Mopar]

I have a 340 with a 4" crank, 727 and 3.23 rear. Highway speed is manageable around 3000 RPM at 70 mph, good acceleration if I step on it and even took it up over a hundred a few times. First and second gears can use a little more gear though. I just did a quick spreadsheet calc with the A41 gear ratio compare to the 727. First and second will be almost like I have a 4.10 rear. Third gear is the same as what I have now. But four gear will be 2.87 and I likely will be around 2500 RPM or less. Still good engine speed and not a problem with a stroker motor. So I would agree with Deezel that this is a good swap. My problem is my 727 has less than 3000 miles and is working perfect, just changed the oil and fixed the pan leak a few months ago. So need to think how much I need to drive to make this worthwhile but I am sure it will be more fun.

[Dmod1974]

The SST A41 is a GM 4L60E.  That trans gets a lot of flak, but it's really only a problem child in stock form because of a few weak stock parts and super soft shift calibration.  Beefed up and tuned properly and they'll take up to about 800 HP in drag applications with low-mid vehicle weight.

I didn't install an A41 per se, but I did have a 4L60E with a TCM that I built/tuned that was behind a 408 stroker for years before restoring my car and Hellcat swapping it.  It ran flawlessly and never had an issue despite tons of abuse and street miles.  A big plus is that you don't need to cut or modify the sheet metal at all.  SST also has a kit to retain the slap stik shifter with a new shift gate for the extra gear position and gear indicator lens.  At the time, they would sell that kit separately.  I don't know if they sell any of it outside of the full kit anymore.

As nice as the gear ratios are in a typical small block application, it's the lock up converter and ability to tune the shift points and line pressure electronically that really make it shine in my opinion.  It let's you have the best of both worlds - comfortable shifts and an early lockup that will make the car drive beautifully on the street, and then have high HP holding WOT shifts with a high stall converter when you get on it.

I had a 4000RPM stall converter that went into lockup in 3rd at relatively low RPM when under low load so the coolant and trans temps stayed low and the fuel economy stayed up along with avoiding that awful outboard motor feel when driving a car with a high stall converter at low speeds.  I consistently got 25+ MPG with that build.  At WOT, it had nice, hard shifts with full stall RPM and 235+psi of line pressure to make sure nothing slipped.

For any naturally aspirated small block build a properly built 4L60E would be a great match.  Big block, nitrous, or blower and you'll be pushing the envelope without spending a ton of extra coin on upgraded hard parts.  At that point, there are better options.

[anlauto]

I installed the A41 from SilverSport works great, customer loves it, still uses the stock shifter etc...nice kit

[chargerdon]

My 74 Chally is a360/408 stroker with still the Magnum 500 14" wheels and a 3.23 sure grip.   I was annoyed at the noise level when cruising at 70 MPH around 3300 RPM not to mention the fuel consumption.

So, I went the A518 route from a 93 Dodge van as described in a thread on here. 

I picked it up for I think $300 and before installing i performed a clutch/seal overhaul on it.  The clutches and all internals were in really good shape, but i felt better having fresh seals in it. 

It went in fairly easily without any floorpan modifications at all and i made a custom transmission mount and console shift lever adaptor that i made. Note..in order to keep the drive angle proper i had to make that custom transmission mount to hold the rear of the A518 as close as possible to the floorpan as its rear is way thicker than the 904 that i replaces.   I also of course had to shorten my driveshaft since the A518 is longer. 

The A518 is actually a 727 with the Overdrive tail section.   It shifts normally via hydraulic pressure thru 3rd gear, but both the overdrive AND locking torque converter are electrically operated which in the 93 van is via its computer, but, in my Chally im using a pair of toggle switches mounted on my console plate to control.   I found that you can leave the OD on continuously and the transmission will then shift from first to second to third and then a brief time into OD at around 35-40 under normal acceleration.  The 408 has enough torque to handle at that low a speed.   On the highway 70 with OD on will be at about 2400 RPM and then engaging the Locking Torque converter drops another 300 to about 2100-2300.   WAY quieter and i get in this mode about 13 MPG on highway driving.   One big issue if i Engage the Lock up and forget to turn it off, the TC will shudder...i have forgotten a couple of times, but so far hasn't damaged it..   I only use the LU feature when on 60+ MPH highways.  Note:  i know some guys have used the diagnostic hydraulic port on the transmission with a pressure gauge to either engage or prevent engaging the Lock up before 50 MPH.   I didn't bother. 

Total cost was $300 for transmission, $125 for overhaul kit, $200 for shortening the driveshaft, $35 for new u joints another $30 for transmission fluid, and about $25 for the steel to make a custom transmission mount, $150 for the lock up torque converter.  Guess that adds up to $850 way cheaper than a gear vendor or other options.   I've had no issues so far with reliability and i do have a heavy foot..

[Duodec]

And for the A518, PATC makes a kit with vacuum and pressure switches that lets you do without manually switching the lockup convertor and overdrive.  That is the route I'm going with my Challenger.

[Brads70]

I have the Keisler A41 kit in my car for like 10 years or more now with no issues! Keisler sold to Silver sport some time ago. I drive it everywhere, been to Carlisle a couple times 7 1/2 hour driving time
DrDiff Dana 60 with 4:10 gears, rear tire is 295/40R18

[MoparLeo]

tparker has not chimed back in. Never gave gear ratio or tire size. These are the great determiners of the final RPM that the engine will run at any speed.
 Here are facts that nobody stated in any of the posts.
What size/diameter tire are you running?

[tparker]

Hi @MoparLeo

My question was more to see if anyone put in a transmission from a modern Challenger. Several people responded with the A41 SilverSport option which I was not aware of. So that was some good feedback, except the price seems quite high. I was looking at some options more than a specific solution. I just don't want the car reving at 3000 rpms while pulling out my drive way. LOL I reality, I'd like to drive it at higher speeds occasionally without sacrificing too much with 2.93 gears. But I'd love to hear more.

As for my setup, It will change. Currently I have stock 14" rims and probably 70 tires. I will upgrade to something. Not sure if that will be 15 or perhaps make the jump to 17 or 19 in rims. The current rear end is whatever gears are in the 7 1/4 but I have an 8 3/4 with 3.23 or 3.55 gears. Forget which, I've had it for a long time.

[Cudajason]

My 74 Chally is a360/408 stroker with still the Magnum 500 14" wheels and a 3.23 sure grip.  I was annoyed at the noise level when cruising at 70 MPH around 3300 RPM not to mention the fuel consumption.

So, I went the A518 route from a 93 Dodge van as described in a thread on here. 

I picked it up for I think $300 and before installing i performed a clutch/seal overhaul on it.  The clutches and all internals were in really good shape, but i felt better having fresh seals in it. 

It went in fairly easily without any floorpan modifications at all and i made a custom transmission mount and console shift lever adaptor that i made. Note..in order to keep the drive angle proper i had to make that custom transmission mount to hold the rear of the A518 as close as possible to the floorpan as its rear is way thicker than the 904 that i replaces.  I also of course had to shorten my driveshaft since the A518 is longer. 

The A518 is actually a 727 with the Overdrive tail section.  It shifts normally via hydraulic pressure thru 3rd gear, but both the overdrive AND locking torque converter are electrically operated which in the 93 van is via its computer, but, in my Chally im using a pair of toggle switches mounted on my console plate to control.  I found that you can leave the OD on continuously and the transmission will then shift from first to second to third and then a brief time into OD at around 35-40 under normal acceleration.  The 408 has enough torque to handle at that low a speed.  On the highway 70 with OD on will be at about 2400 RPM and then engaging the Locking Torque converter drops another 300 to about 2100-2300.  WAY quieter and i get in this mode about 13 MPG on highway driving.  One big issue if i Engage the Lock up and forget to turn it off, the TC will shudder...i have forgotten a couple of times, but so far hasn't damaged it..  I only use the LU feature when on 60+ MPH highways.  Note:  i know some guys have used the diagnostic hydraulic port on the transmission with a pressure gauge to either engage or prevent engaging the Lock up before 50 MPH.  I didn't bother. 

Total cost was $300 for transmission, $125 for overhaul kit, $200 for shortening the driveshaft, $35 for new u joints another $30 for transmission fluid, and about $25 for the steel to make a custom transmission mount, $150 for the lock up torque converter.  Guess that adds up to $850 way cheaper than a gear vendor or other options.  I've had no issues so far with reliability and i do have a heavy foot..

Same here, I went with the A-500 mainly because thatis what I could find locally.

here is my very long thread on it.

 https://forum.e-bodies.org/engine-transmission-and-rear-end/4/rh-transmission-the-result/12648/

Best mod to the car ever, cruising down the road at 55mph adn only 1600 rpm or so...no chug nothing just smooth sailing! Drop to second and look out!!!

I guess it all depends on what you want to do with the car, but this is a budget friendly way to get an OD in a small block. with no major mods.

Jason 

[MoparLeo]

I don't about 3k rpm out of your driveway. Wheel size has little to do with tire size and nothng to do with the tire diameter.
As far as a modern Challenger transmission, nobody mentioned the 8HP70 trans that is currently used. Probably because it is very large and requires more than a little tunnel modification to fit and is also very expensive and needs to be computer controlled. Not cheap or easy.
 The transmissions that have been mentioned are just modified older model transmissions. Nothing new.
Here is a tire diameter/rear ratio RPM calculator.
https://www.bgsoflex.com/rpmmph.html

[chargerdon]

I don't about 3k rpm out of your driveway. Wheel size has little to do with tire size and nothng to do with the tire diameter.
As far as a modern Challenger transmission, nobody mentioned the 8HP70 trans that is currently used. Probably because it is very large and requires more than a little tunnel modification to fit and is also very expensive and needs to be computer controlled. Not cheap or easy.
 The transmissions that have been mentioned are just modified older model transmissions. Nothing new.
Here is a tire diameter/rear ratio RPM calculator.
https://www.bgsoflex.com/rpmmph.html

Excuse me but the wheel diameter and the tire size on it have a huge bearing on the tire diameter !!
Example...on my challenger i have 235x60x14 in tires and rims.   235mm=9.25 inches...x .60 =5.5 sidewall height.x 2 (top and bottom) inch = 11 plus 14 diameter wheel and i have 25 inch tall wheels.  A lot of the bigger engined Challengers came with 15 inch wheels and people have put 245x60x15 tires on...that would be 9.64 x 60 = 5.8 sidewall x 2 + 15 = 26.5 inch tall.   or how about moden 17" wheels 240x65x17 comes out to 29 inches.   Plug 25 and 29 into that calculator and you get large differences !!
=

[dodj]

A41 SilverSport option which I was not aware of. So that was some good feedback, except the price seems quite high.

Ya, a year or two ago I looked at that option. Too expensive to me. The 440 revs a little higher than I want on the hwy at 65-70mph but long trips down the hwy isn't it's primary purpose. So I live with it.