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over drive auto tans

68GTS340

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Jul 17, 2008
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Location
western new york
what is recomended for a 500 hp (approx ) big block street car. ?
looking for four speed with a lock up converter.... or what is the best for street use and fuel milage ?
 
Either a gear vendors or a well built 518 etc. Phoenix Transmissions is in my area. They have done trannys for One Lap cars. They can do you a OD to handle 500hp without a problem. It's the only shop I've ever used that built a trans that did exactly what I wanted it to do.
 
Keisler does an OD auto base on the GM 4L65E. I haven't used their kit, but it looks very well done. I have done their 5spd conversions plenty of time and am very happy with the products, performance and support. Have I had problems? Sure, but it was never anything that couldn't be overcome and the support at Keisler was always friendly and on top of it.

Rev.
 
Hi Rev,
I have an a518od in a 71 Duster. Its mostly a street car and I love the od. The install required alot of floor mods tho. I got 16+ mpg running a steady 80/85 on the interstate on a AZ to MN trip last summer. However for strictly performance application It might not be the best choice. Changing out the 727 I slowed from 14.68 to 15.00 (360 with a 3.23 rear). Probably the added weight as well as hydraulic and rotational losses associated with the OD section.
I got a lot of info from SMR trans, www.smrtrans.com. The A518 is for a smallblock only but conversions are available. On Moparts.com there is alot of photos of a conversion using a JW Ultrabell. Look in tech for "BIG BLOCK A518 OVERDRIVE CONVERSION".
Transtech Transmission Specialists of Dubuque IA will weld on a BB bellhousing from a donor 727.
Back in the June 07 Mopar Action mag they put Keislers set up in a 69 Road Runner. They comment on the lower 1st gear helping out too. The only floor pan mod they mention is to roll over the pinchweld at the floor to cowl point and a few hammerblows to the right side tunnel.
I did all the work myself so the 518 was the cheapest route for me, but If I had to pay I think the Keisler is good choice. A couple people I know have the GV od and they say they have a little more drivetrain vibration than before, but I bet the GV can handel more HP.
 
Last edited:
yes,
I have their vacuum and pressure switch kit on the A518 in my Duster. It works just as they advertise. The guy I talked to there was helpful and willing to talk about their stuff.
but I don't have any info on their other products.
 
Hi Rev,
I have an a518od in a 71 Duster. Its mostly a street car and I love the od. The install required alot of floor mods tho. I got 16+ mpg running a steady 80/85 on the interstate on a AZ to MN trip last summer. However for strictly performance application It might not be the best choice. Changing out the 727 I slowed from 14.68 to 15.00 (360 with a 3.23 rear). Probably the added weight as well as hydraulic and rotational losses associated with the OD section.
I got a lot of info from SMR trans, www.smrtrans.com. The A518 is for a smallblock only but conversions are available. On Moparts.com there is alot of photos of a conversion using a JW Ultrabell. Look in tech for "BIG BLOCK A518 OVERDRIVE CONVERSION".
Transtech Transmission Specialists of Dubuque IA will weld on a BB bellhousing from a donor 727.
Back in the June 07 Mopar Action mag they put Keislers set up in a 69 Road Runner. They comment on the lower 1st gear helping out too. The only floor pan mod they mention is to roll over the pinchweld at the floor to cowl point and a few hammerblows to the right side tunnel.
I did all the work myself so the 518 was the cheapest route for me, but If I had to pay I think the Keisler is good choice. A couple people I know have the GV od and they say they have a little more drivetrain vibration than before, but I bet the GV can handel more HP.

Curious about the GV setup and the vibration. It must stick out quite a bit further than the STD 727 tail shaft and I would think drive shaft alignment could be affected. Maybe raising or lowering the tail shaft could solve the vibration? Side to side is also important, especially on a MoPar because the yokes are in phase. Does the floor need any modifying to install the GV?

I was hoping to use some form of OD on my 68 RR 383/727 because I plan to drive the car alot and would like to get something reasonable in the MPG dept. Anyone have any MPG data on a big block A/T B body with OD??
 
interesting what meep-meep says about the gear venders and the vibration. Alot of guys love their gv, but i know someone who hates his for the exact reason mentioned. He also thinks the gear splitting is a gimmick and that the only good thing about it is the OD. Im not sold on the idea myself.
 
The longer shaft throws off the pinion angle... giving a vibration sometimes....

my boss's Superbird... I got 27mpg in that bad boy.... 440+6 4-speed with a 3.54 Dana.... pretty easy when you swap in an aluminum case 833 OD
 
27 MPG!!! That's amazing! Is the odometer working??? Haha. It must be an original 4 spd bird, so the swap is easy and makes sense if you want a cruiser. My 68 is an auto car so I would like a good solution that does not require major floor surgery. I have a 518 non lock up trans but I heard you gotta hack the floor and I'm not going to do that - again. Once I fix the floor from my 4 spd install 25 yrs ago, that's it, no more hacking!!
 
We drove 400 miles round trip last weekend to the Branson Super Summer Cruise and got almost 30 mpg with a 5.9 efi and A518 overdirve and 3.55 gears. All this in a 73 Cuda.
 
interesting what meep-meep says about the gear venders and the vibration. Alot of guys love their gv, but i know someone who hates his for the exact reason mentioned. He also thinks the gear splitting is a gimmick and that the only good thing about it is the OD. Im not sold on the idea myself.

does he want to sell it , I would love a GV
 
I think I would like one too!! Put me down second in line behind moparstuart.
 
Well, he's put alot of time and effort into getting the GV working (according to him it doesnt work as it should) so i figure he will hang onto it. He did tell me if he knew what he knows now, he wouldnt have gone that route but would have gone the A518 route but i think that requires some mods too?
 
The Tranztech conversion gives you a lock-up torque converter that helps cooling. there is no vibration and the overall length is 2-2.5 inches longer. the best part is no bow tie parts in my mopar, no computers, all the cooler lines and linkage are a match and way cheaper than a gv. these tranztech conversions are said to hold at least 500 hp. if your looking for a drag car and every second matters, all overdrives will add lbs and slow you down. if you like to drive your car and light em up every now and then, like me, this is the way to go. they even made the top 10 in mopar collectors guide. I have had mine for a few years, no problems, and love I it.
 
Why not use a 200r4 or 700r4? I've heard the 200r4 will fit in an abody with only notching the upper cross member and Wilcap sells adapter plates for them. I've searched around n I can't seem to find anything on a b-body swap but there are ppl puttin em in abodies.
 
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