Transmission Swap – 727 to 518 / 46 RH in 68-70 B-body

[Needa68]

I'd like to speak with someone who has actually converted a 68-70 b-body with big block engine and center console shifted 727 transmission to a 518 /46 RH transmission. If you do not wish to provide your phone number via this forum, please contact me by e-mail. My email address is:  rhmitch@outlook.com
Thank you in advance.

[68CoronetRT]

Why do that swap when a Gear Vendor will be maybe a little more and will bolt right into your existing setup?

Be alot stronger than the 518. I've been reading up on this swap alot lately and GV seems to be the better choice.

[Mike DC]

 
GV is a 0.78 overdrive ratio and no lockup converter.  The OEM tranny is more like .69 ratio and the later ones have a lockup.

If you start at 4000 rpm, the GV would knock it down to 3100 rpm.  An A518 with a lockup would be more like 2500 rpm.


But the A518 won't fit without cutting stuff, and even then it still hangs down 1" lower than stock . . . and then there are the GM options . . . this is a longer conversation.

[Troy]

There are several build thread here where an A518 was installed. As mentioned, it's physically larger than a 727 and won't fit without some mangling of the floor pan.

Do you have a small block engine? If not, you'll also want to find someone who has installed the Ultrabell.

Troy

[Midnight_Rider]

There are several build thread here where an A518 was installed. As mentioned, it's physically larger than a 727 and won't fit without some mangling of the floor pan.

Do you have a small block engine? If not, you'll also want to find someone who has installed the Ultrabell.

Troy

It looks like there's an adapter kit which would be an alternative to the Ultrabell. Expensive, but might be worth investigating?

http://smrtrans.tripod.com/smrtransmissionsintro/id9.html

[Kern Dog]

CDR did the swap and made his own crossmember.

I have been considering an overdrive swap for my 70 Charger. I had a Gear Vendors for awhile but I wasn't completely happy with it. The Silver Sport Overdrives GM based transmissions are a very attractive option. 4 speed, Lockup converter, a .70 O/D and a 3.06 first gear.

[J.Bond]

Been thinking about this for a while. Have had several conversations with Ron (Big Sugar) who did do the Ultrabell.  He had the adaptor plate assembly, but. decided to do the Ultrabell instead, and sent the adaptor back. Something tells me the adaptor assembly is stronger, however, it moves the transmission even further back. And the Ultrabell hook up seems to be the weak link, not that I have heard of any failures. The past week,  I have been seriously considering Gear Vendors as an alternative to hacking up as little as possible.

K.D.

Why were you not completely happy with it?

[cdr]

Been thinking about this for a while. Have had several conversations with Ron (Big Sugar) who did do the Ultrabell.  He had the adaptor plate assembly, but. decided to do the Ultrabell instead, and sent the adaptor back. Something tells me the adaptor assembly is stronger, however, it moves the transmission even further back. And the Ultrabell hook up seems to be the weak link, not that I have heard of any failures. The past week,  I have been seriously considering Gear Vendors as an alternative to hacking up as little as possible.

K.D.

Why were you not completely happy with it?

The ultrabell set up is used on MANY VERY high HP race cars , it is not light duty LOL!!

[fizz]

I believe the silver sport l460e trans conversion I used is one of the best things I did to my car. I used the 650 torque option. That is pretty close to what my engine puts out. Been beating on it, no problems, but only 2000 miles so far. 391 gears, and 2600rpm at about 75 mph. Only problem with install was TTI headers, because of the deep cast trans pan, had to turn pass side collector out a few degrees. Kit was absolutely complete, tech assistance was great.

[Midnight_Rider]

I believe the silver sport l460e trans conversion I used is one of the best things I did to my car. I used the 650 torque option. That is pretty close to what my engine puts out. Been beating on it, no problems, but only 2000 miles so far. 391 gears, and 2600rpm at about 75 mph. Only problem with install was TTI headers, because of the deep cast trans pan, had to turn pass side collector out a few degrees. Kit was absolutely complete, tech assistance was great.

Thanks for posting your experience. What did you do for a shifter?

[Kern Dog]

The Gear Vendors unit worked fine but there were some snags.
1)The speedometer output exits too close to the floor. It needs a 90 degree adapter to avoid binding the cable. My speedo drive broke and GV didn't know when they'd have any more to sell.Because of this, I tried using a regular setup. The problem is that the speedo drive exits at a strange angle. The traditional Mopar 727 and 904 speedo exits at the 9:00 position as viewed from the rear. The GV exits at a 10 or even a 10:30 position. I had to bang on the floor to get the cable to fit.
2)There was always some vibration. This could have been from the driveshaft itself though. The unit I had was one of the early units with a fixed output yoke. This required a drive shaft like what you see in the front of a solid axle 4wd: The type with a "slip and spline" connection that allows the shaft itself to extend or compress. After I sold it, I learned that the yoke actually could be unbolted allowing the use of a traditional slip yoke shaft. Yes, I felt like an idiot.
3) The early style electronics were crude. What I wanted was for OD to engage at a preset speed then disengage as I slowed down. Instead, it would kick into OD at 45-50 mph but stay in OD even as I came to a stop. This was annoying if I wanted the real 3.91 gear to launch me instead of the 3.91 X .78. (3.05 final drive)
4) The floor shifter in factory applications required a car transmission. These had a boss that was cast into the tail housing. This boss allowed attachment of a bracket that supported a critical part of the shifter linkage. The GV I had did not have this so a custom bracket was made. Because of the added width of the  GV, the shifter "bellcrank" was positioned out of plumb which messed with the geometry a bit. This caused the shifter to feel a bit vague and sometimes NOT stay in the PARK position. The car would sometimes roll away from me when I got out of it!

Oh, I understand that the SST transmission kits do have a replacement shifter that is a hybrid to allow the use of a cable instead of a linkage arrangement.