Quote:

---

The GV unit will take 0hp away from your normal 3 speed operation where as the A500 is always robbing some hp because it drives thru the OD all the time. They say it can rob as much as 1sec in ET...

---

Quote:

---

Before I committed to it I asked around if this transmission would be a good choice for a motorhome (weighs 6500 pounds) and was told that the overdrive part would be too weak for this application. I ended up just building a standard 727. I would have liked the extra mileage. Now I have a new '74 camper which is around 7000 pounds and interested in overdrive again but this rig already has a good 727 in it and wonder if this shortie overdrive would work.

---

So they didn't think the 518 would work in a 6500-7000lb motor home but it works just fine in dodge pickups that weigh 5000lbs on their own + tow that much in trailers, cars, campers, etc. A good rebuild kit and the transgo tfod-hd2 shift kit is the ticket. With the right combination of parts you can also install extra clutches in the overdrive tail unit.

Quote:

---

Quote:

---

The GV unit will take 0hp away from your normal 3 speed operation where as the A500 is always robbing some hp because it drives thru the OD all the time. They say it can rob as much as 1sec in ET...

---

I have never seen one scrap of evidence to back up this claim. Not saying it's impossible, but I have never seen anything to substantiate this at all. Until I see a real, all things equal comparison between the two, I'm going to have to put this one right up there with the other myths like the thin wall 70's 440 blocks and low nickel late 70's mopar blocks.



smr transmissions did a comparison on a small block dodge dakota between a 727 and a 518. Lost a full second e.t. with the 518. Same truck, engine, rear and track.

Quote:

---

Here is the shorty..

http://smrtrans.tripod.com/smrtransmissionsintro/id32.html

---

THE "Shortie" overdrive option can be added to any of the above transmission models for the additional cost of $2,825.00.

I just lost interest!

Quote:

---

Quote:

---

Here is the shorty..

http://smrtrans.tripod.com/smrtransmissionsintro/id32.html

---

THE "Shortie" overdrive option can be added to any of the above transmission models for the additional cost of $2,825.00.

I just lost interest!

---

Quote:

---

smr transmissions did a comparison on a small block dodge dakota between a 727 and a 518. Lost a full second e.t. with the 518. Same truck, engine, rear and track.

---

I'm sure a company that specializes in 727 and 904 AND sells the gear vendors units is absolutely unbiased.

Where's the data? Specs on the transmission builds? Was this a bone stock w/ stock converter 518 left in drive versus a 727, converted to roller internals with an aftermarket converter, valve body and shifted manually?

Take a stock unrebuilt 727, stock unrebuilt non-lockup 518(so you can put the same converter on both) and actually rebuild both transmissions COMPARABLY. Then run then down the track 10 times each and get back to me. Until someone does that, everything is heresay and myth.

Quote:

---

Quote:

---

smr transmissions did a comparison on a small block dodge dakota between a 727 and a 518. Lost a full second e.t. with the 518. Same truck, engine, rear and track.

---

I'm sure a company that specializes in 727 and 904 AND sells the gear vendors units is absolutely unbiased.

Where's the data? Specs on the transmission builds? Was this a bone stock w/ stock converter 518 left in drive versus a 727, converted to roller internals with an aftermarket converter, valve body and shifted manually?

Take a stock unrebuilt 727, stock unrebuilt non-lockup 518(so you can put the same converter on both) and actually rebuild both transmissions COMPARABLY. Then run then down the track 10 times each and get back to me. Until someone does that, everything is heresay and myth.

---

Quote:

---

The 518 can in no way rob more HP than a GV. The 518 only adds roteing weight in 1st 2nd and 3rd, no other "drag" is added, the pump is not doing any work holding clutches or bands or line preasure or any thing. The GV adds a similar amount of rotateing weight in all gears combined with an almost useless extra gear. The OD section can easily have clutches added, if you use the 48RE OD section it can handle 800 lbs tq easily!

As for the 1 second difference in ET from a 727 to a 518 I say BULL CRAP! Like I mentioned earlier, there is a few pounds added to the rotateing weight, thats IT! In first second and third there is some extra weight and in no way can those few extra pounds knock off 1 second in ET. If the trannys get equal prep it can't be more than a couple tenths. If 5-10 pounds in rotateing weight could really knock off 1 second then every car could switch from a steel drive shaft to carbon fibre and gain a second

---

Show us the math on the "worthless extra gear". I'll even give you the parameters. 3.73 rear gear, 28" tall rear tire, 4000lb car.

Also has anyone factored the cost of modifying the trans tunnel or the loss of perceived value with a hacked up cross member?

Quote:

---

Quote:

---

The 518 can in no way rob more HP than a GV. The 518 only adds roteing weight in 1st 2nd and 3rd, no other "drag" is added, the pump is not doing any work holding clutches or bands or line preasure or any thing. The GV adds a similar amount of rotateing weight in all gears combined with an almost useless extra gear. The OD section can easily have clutches added, if you use the 48RE OD section it can handle 800 lbs tq easily!

As for the 1 second difference in ET from a 727 to a 518 I say BULL CRAP! Like I mentioned earlier, there is a few pounds added to the rotateing weight, thats IT! In first second and third there is some extra weight and in no way can those few extra pounds knock off 1 second in ET. If the trannys get equal prep it can't be more than a couple tenths. If 5-10 pounds in rotateing weight could really knock off 1 second then every car could switch from a steel drive shaft to carbon fibre and gain a second

---

Show us the math on the "worthless extra gear". I'll even give you the parameters. 3.73 rear gear, 28" tall rear tire, 4000lb car.

Also has anyone factored the cost of modifying the trans tunnel or the loss of perceived value with a hacked up cross member?

---

Quote:

---

Quote:

---

Quote:

---

The 518 can in no way rob more HP than a GV. The 518 only adds roteing weight in 1st 2nd and 3rd, no other "drag" is added, the pump is not doing any work holding clutches or bands or line preasure or any thing. The GV adds a similar amount of rotateing weight in all gears combined with an almost useless extra gear. The OD section can easily have clutches added, if you use the 48RE OD section it can handle 800 lbs tq easily!

As for the 1 second difference in ET from a 727 to a 518 I say BULL CRAP! Like I mentioned earlier, there is a few pounds added to the rotateing weight, thats IT! In first second and third there is some extra weight and in no way can those few extra pounds knock off 1 second in ET. If the trannys get equal prep it can't be more than a couple tenths. If 5-10 pounds in rotateing weight could really knock off 1 second then every car could switch from a steel drive shaft to carbon fibre and gain a second

---

Show us the math on the "worthless extra gear". I'll even give you the parameters. 3.73 rear gear, 28" tall rear tire, 4000lb car.

Also has anyone factored the cost of modifying the trans tunnel or the loss of perceived value with a hacked up cross member?

---

the worthless extra gear comment meaning this:

3rd (direct) at 75mph with 28" tires and 3.73 assuming no converter slip: 3350 RPM, mist likely 3500 w/converter slip

gear vendors OD drops it to 2650 RPM no converter slip, most likely 2800-2850 with slip

518 OD drops it to ~2320 RPM, with no converter slip. you won't have converter slip if using a lockup converter...

IMHO a .78 OD is not enough OD to warrant the cost... [/quote}

Cost aside - 700 rpm drop is not worthless. The 518 is better from that standpoint, but what option do you have if you don't want to hack up your car? Keisler GM adaptation? Better first ratio and as good or better O/D ratio.

Quote:

---

Also has anyone factored the cost of modifying the trans tunnel or the loss of perceived value with a hacked up cross member?

---

Well if you can't manage the tunnel/crossmember mods yourself, then chances are you can't fab your own trans mount for the 518, and chances are you can't build your own 518 either. So if you have to farm all that out, you are probably at the same $ level as a gear vendors.

FWIW, the OP asked about a 72 charger. A 72 charger will not need the tunnel or crossmember modded. A 70 or earlier b-body would need those mods. If you have a car that would need the crossmember modded, and you're not comfortable with that, then yes chances are you would be happier with a gear vendors or a chevy 700r4 based auto like the keisler 4-sp auto. Also, from what I've gear, the gear vendors units still do require you to your tunnel for clearance. You don't have to and but it's not a straight bolt in either from what I've read.

Quote:

---

Cost aside - 700 rpm drop is not worthless. The 518 is better from that standpoint, but what option do you have if you don't want to hack up your car? Keisler GM adaptation? Better first ratio and as good or better O/D ratio.

---

Quote:

---

Cost aside - 700 rpm drop is not worthless. The 518 is better from that standpoint, but what option do you have if you don't want to hack up your car? Keisler GM adaptation? Better first ratio and as good or better O/D ratio.

---