Rh46 or gear vendors

[Slug]

73 challenger, with 340,727 trans and 3.90 rear. Should I go with a rh46(which I have bugs needs to be rebuilt) or gear vendors? Which one will be easier to install?

 

[Chryco Psycho]

The Gear vendor OD is likely a simpler install , but it will lengthen the trans & change the driveline angle requiring a shorter driveshaft & possibly a CV joint in the driveshaft . You also need to clearance the driveshaft tunnel slightly not cutting just denting for clearance.
The RH46 is also likely longer & may cause the same issues + adapting it to the block & possibly cutting the tunnel .

 

[Slug]

Thanks

 

[DrEamer]

I'm doing the 46RH , but considered the Gear Vendors as well. I have only mocked up everything, so I can't give you any information on how well it works. That said, I can tell you things that you have to consider when going with the 46RH. The transmission went in with no altering of the tunnel, but you will have to work over part of the linkage, and cut a couple of notches into the transmission itself. Also, you will need to modify the crossmember, or buy one made for the conversion. Since the 46RH came behind small blocks, then it is a bolt on, unless you are using one from a diesel, which I do not know if they work. The torque converter has the lock up feature, which in nice, but only a few places make ones meant to handle higher performance applications. The torque converter itself, and flex plate MAY need to be changed to neutral balanced to match your 340, since the Magnum engine that they came behind used external balance. If you decide to go with the 46RH, I would be glad to help with sourcing parts for you.

 

[Slug]

I'm leaning towards the rh46 since I have one in the garage. When i start the work I'll definitely pick your brain.

 

[Stylin'Stainless]

Sounds like you pretty much know what direction you want to go in and I wish you the best of luck.
I also chose the 46RH route because I thought I could save a few bucks, I liked the idea of keeping the car all MOPAR and honestly - I always seem to choose the hardest route. I PERSONALLY WOULD NOT DO IT AGAIN.
I put mine behind a 426 with the use of an Ultra Bell. They do come in both lock up and non lock up versions so make sure you know which one you are getting/have. The lock up offers a little bigger RPM drop in OD. Also, ensure you truly have a RH and not the sister RE which controls the OD electronically. I had to trim the tunnel brace between the torsion bars (B-body) and then box it back in, trim the tranny, trim the pinch weld between the firewall and floor pan then weld back up, dent the floor, shorten the driveshaft, modify the shift linkage, fab a new crossmember, plumb in pressure switches through a vacuum switch for automatic engagement and disengagement of the OD and lock up converter and have a "looser" torque converter built. For price sake, I won't even include the cost of a new Ultra Bell ($500).
Not quite sure why you would have to add a CV as these are mostly required for longer drive shafts.
SO, why would I not do it again? After I was done with a beefy build of a 46RH and addressing all of the other challenges, I could have bought a GV for the same price. But most of all the GV adds four more gears instead of just an overdrive. Not to mention that a GV is stronger and can take more abuse than the OD unit bolted to the back of a A518 46RH. JMO, speaking from experience of course
In all fairness my rebuild/up-grade was more expensive than yours probably needs to be because I wanted to ensure the internals could handle the torque of the Elephant. At the very least, I suggest you do what I should have done: Drive a Gear Vendors equipped car BEFORE you make your decision. Best of luck to you Sir!

 

[Slug]

It's probably not worth it for me to do either one then. I'm only on the highway 3 or 4 times a month in the summer. It just stinks watching the tach around 4k when im going 70-75mph.

 

[Stylin'Stainless]

Slug...Don't let me discourage you!!!! It's definitely worth it! You will enjoy the car a whole lot more and save some wear and tear on the engine. Just trying to share some of my mistakes (and I have made lots of them) so that you can be mentally and financially prepared. I have a '57 Belair with 270:1 gears and a 4L60E overdrive and it's so nice cruising at 75 mph with tons of pedal left.
Either way you decide to go you won't regret the result! The goal, IMO, is to avoid regretting the path you chose to get there.

 

[340cudakf]

I went with the gear vendors in my 340 Cuda. It works well with the 3.55 sure grip.

 

[Slug]

Did you have to cut out any of the floor pan to make it fit?

 

[340cudakf]

Did not have to cut floor pan. Had dent small area with a hammer. It is close, about 1 inch clearance all around. But it did fit. I have some pictures, but the file is to big to fit on this page? If you want to see pictures my email is circlefexhaust@gmail.com

 

[Slug]

Thanks,I'm still up in the air on what I'm going to do. It seems like gear vendors is easier to do especially now, that since you said no cutting.

 

[John Rimel]

Price both mods out. If you want a fresh setup rebuilding the trans, buying a new converter and doing the mods to make it work I think you’ll find to be more $$

 

[DrEamer]

Price both mods out. If you want a fresh setup rebuilding the trans, buying a new converter and doing the mods to make it work I think you’ll find to be more $$

I think that is spot on. If your 727 is in good shape, and you are happy with the converter, then it should be less money to go with the Gear Vendor. The only labor you might incur is having someone swapping out the tail shaft if you do not want to do it yourself. You will have to shorten the driveline with either option, so the cost is the same there.

Now, if you need a rebuild the 727, the 46 RH might be less depending on the price to rebuild each. In my case, I was starting with nothing. I landed a core 46RH for basically free, so I am into it for the price of the rebuild, conversion crossmember ,converter, and controller. If I had found a 727 in good shape, I might have gone with the Vendor, but knowing me, I would of wanted to have anything I bought rebuilt anyway. Either way, you will like driving it more which ever way you decide.

 

[CudaJason]

I think that is spot on. If your 727 is in good shape, and you are happy with the converter, then it should be less money to go with the Gear Vendor. The only labor you might incur is having someone swapping out the tail shaft if you do not want to do it yourself. You will have to shorten the driveline with either option, so the cost is the same there.

Now, if you need a rebuild the 727, the 46 RH might be less depending on the price to rebuild each. In my case, I was starting with nothing. I landed a core 46RH for basically free, so I am into it for the price of the rebuild, conversion crossmember ,converter, and controller. If I had found a 727 in good shape, I might have gone with the Vendor, but knowing me, I would of wanted to have anything I bought rebuilt anyway. Either way, you will like driving it more which ever way you decide.

I did this swap last year in my 74, well a 42RH as opposed to the 46RH. I can tell you it is worth the effort. Even after only 150 miles on mine, I see the benefits.

On the highway, it is amazing, cruising at 70 MPH and only turning 2200 or so RPMs makes me want to stay on the highway even longer. Around town, let it go into OD just cruising, and it makes a noticeable difference, my 360 just seems happier at the lower rpms.

In terms of cost, I purchased the trans, rebuilt it, new fluid, new TQ converter etc. etc., purchased a new driveshaft, a welder, and a 12 ton press for maybe $2000 CAD (the drive shaft was $500 of that) maybe it was a bit more, but no where near the cost of the GV unit at $3000 USD. Some of those costs you will have any way, like the driveshaft. I did not upgrade the trans with performance improvements outside of a Trans 2go shift kit, but I am not running a big crazy HP ending either.

The biggest component of the swap was time...I had to lean to rebuild a trans (there is a great video on the 46RH if you need one), learn to weld and build the cross member, and the do all of that, so it took some time. You would have some time into the GV install too.

I say go for the 46 RH.

 

[John Rimel]

Well, I took the plunge and went with a 518. Went with Monster transmissions. I get a fresh trans and an included fresh converter. There’s a modification sold through PACT that makes the converter lockup as well as OD automatic. It’s a preset system for either 48mph or 52mph. Since the surface streets are 45mph I decided to go with 52mph.