Overdrive Options

[Tjfly4pay]

I've thought about it a lot actually, even if you weren't as gifted as myself to have a shop, You still have to fabricate a cross-member either way. The cost to cut out and weld in a 1/4 piece of steel for the torsion bar support is laughable. We're splitting hairs here. For me it costs $700 to put in a 42RH with a decent torque converter. I lost count what Mopar to ya spent on his 200r4. As far as putting more power to the ground with 200R4 vs 42RH I still don't see conclusive evidence of parasitic loss between the two. Still going 42RH. Not going to debate further until I see something concrete.

Prior to switching to the 727, I could have given you a front row seat to parasitic power loss due to the MOPAR transmission. Now I guess you will get to see for yourself. Like I said... If all you are wanting is the final gear ratio to be close to 3.0 or something like that... Things are cool. If you want good acceleration, I am certain my car would have been much stronger with a 3.0 ish rear end ratio and a 904 or 727 than it was with 3.91 gears and the .69 overdrive transmission.... Much faster. On another note.... I did like the lock up converter!!! Mine was right at $1000 for 2800 stall speed. Todd

PS. Just putting a 1/4 piece of steel in place of the torsion bar support is not strong enough. There are huge amounts of load on that support!!! As I did the calculations on the strength that the factory support, I was surprised to find out how strong it was, and what it would take to achieve the same amount of support from replacement parts. Flat steel just won't do it. FWIW.

 

[LJS30]

Yes the OD is being driven all the time.... Whether it is engaged or not.
It is an add on to the rear of a 904 or 727 (500/518 respectively). It is NOT a 4th gear inside the main case of the transmission. You ask "why would MOPAR build a trans...?". Because while it is very true that the acceleration would be greatly affected, once it is spun up to highway speed.... Now your parasitic drag has been neutralized, or at least minimized. So the .69 will still give you a better cruise performance and mileage.
I hope a trans tech speaks up here, but I can tell you what the difference feels like and it is dramatic!!!!
Look, I don't want to bash anyone's hopes, dreams, and expectations.....
However, I would like people to know, and not be disappointed when their project doesn't work the way they expect it to. This OD from MOPAR I think was an initial attempt at getting better gas mileage.... They have come up with better technology since then.
While my car with the 518 impressed everyone that I ever took for a ride, it is now unbelievable!!! The horsepower that has been freed up, makes this car run amazing..... First and second gear are like being on ice....
I wanted to retain the OD, AND DIDN'T WANT TO BELIVE THAT WAS THE PROBLEM!!!! Now I have a new problem..... I gotta buy some sticky tires!!!
Now that's a good problem to have, if you ask me!!! Todd

Very interesting indeed. But how about if all you want is a street machine with some solid performance and a better mileage? What if you don't plan on taking it to the strip? Was the 518 acceptable?

 

[Revhendo]

Very interesting indeed. But how about if all you want is a street machine with some solid performance and a better mileage? What if you don't plan on taking it to the strip? Was the 518 acceptable?

Starting to get the impression that none of these options are inexpensive? There are some installs that are less expensive than others, but nothing like going to a junkyard and grabbing a used unit and just slapping it in. Not for us unfortunately.

 

[Tjfly4pay]

Very interesting indeed. But how about if all you want is a street machine with some solid performance and a better mileage? What if you don't plan on taking it to the strip? Was the 518 acceptable?

Personally I don't think the 500/518 is a good option. While my car never ran hot, it did work harder all the time than necessary, and therefore I would stay away from this transmission. Knowing what I know now, I would much rather have a 3.0 ish (3.23 or the like) rear axle ratio rather than this particular 500/518 transmission.

 

[DionR]

About the cheapest swap I can come up with is a low mileage MA5 out of a Colorado or similar, with a 94-99 (I think) Dakota bellhousing.

There is an MA5 local to me for $450 with 60K, and the bell is $50-100. Still have the cost of a clutch, and any other miscellaneous parts if your car isn't already a 4 speed, plus a hydraulic master cylinder conversion of some type, and it is far from a "slap it in" conversion as the floor and crossmember will need as much work as a T56 swap, but I bet is still cheaper in the end than Tjfly4pay's lockup converter.

The MA5 does have a 3.753 first gear, kind of deep, but I think it's workable. They seem to work well in the Solstice with an LS swap. Seems like a really good match to a high rpm motor, to me.

 

[magnumdust]

About the cheapest swap I can come up with is a low mileage MA5 out of a Colorado or similar, with a 94-99 (I think) Dakota bellhousing.

There is an MA5 local to me for $450 with 60K, and the bell is $50-100. Still have the cost of a clutch, and any other miscellaneous parts if your car isn't already a 4 speed, plus a hydraulic master cylinder conversion of some type, and it is far from a "slap it in" conversion as the floor and crossmember will need as much work as a T56 swap, but I bet is still cheaper in the end than Tjfly4pay's lockup converter.

The MA5 does have a 3.753 first gear, kind of deep, but I think it's workable. They seem to work well in the Solstice with an LS swap. Seems like a really good match to a high rpm motor, to me.

I have a colorado w/ a 5spd. The trannies are pretty stout, but the other problem is that it would still require tunnel mods w/ regard to the crossmember.

 

[DionR]

I have a colorado w/ a 5spd. The trannies are pretty stout, but the other problem is that it would still require tunnel mods w/ regard to the crossmember.

Yep.

Really the cheapest and easiest is the factory A833OD if you want an overdrive. If it is already a 4 speed car, it is by far the cheapest and easiest, and doesn't require any crossmember mods.

I have been running an A833OD with a 2.71 rear gear and it really isn't too bad, but I've got a high torque 360, too. Run a 3.55 and you will be more than pleased.

Is it the best? No. Are there better options? Not for the money.

 

[Woods74]

I'm a bit confused by your $700 figure. This is a rebuilt performance trans with a performance lock up converter? The last performance converter I bought for my 727 was something like $300. So you're saying I can do the rest of the conversion for less than four C notes? Buying a core trans, stripping it, cleaning it, putting it together with upgraded parts? Not to mention getting the Hobbs switches and wiring them in. Of course there is the one fifty or so that my driveshaft shop is going to nick me for shortening the driveshaft and balancing. I just bought a case of trans fluid and it cost me $70 bucks. You're not just gifted, you're magical.

The plan is: Use my account at wittrans.com for the rebuild parts, use a 24-2600 edge converter, and for OD/LU control I'm going GM TH400 kickdown switch since I have one handy, and use the Surburban out back for the mount.

$150 for a couple switches is a goddamn outrage in the day we live in. No overpriced switches for me. You can procure them individually way cheaper.

I got my 95 42RH core for about $120 if memory serves. The one with the slotted hub so its less prone to breakage.

I have alot of the upgraded parts from my a904 fiasco left over I'm gong to use. I.E. 3.8 kickdown lever, beefy band strut, billet low/reverse accumulator the one with the sweet seals that can't get cocked in the bore.

I'm going to take a shot at cutting the driveline myself, just for fun. Last time was a complete ripoff. With that said:

http://www.4xshaft.com/

This guy cuts drive lines for $65 bones, return shipping is on the house. He does good work and is a very nice guy from what I'm told.


As far as that torsion bar mount, I think people are wayyyyyy to sensitive about cutting it out. Especially with the use of a 1/4" loop. Plus, did you see that beefy cross member everyone builds or is it just me?

That has TONS of torsional strength.

That in addition to the frame connectors your suppose to have in there negates any issues.


Or maybe I'm just a wild a**hole. Time will tell, something tells me the sky won't fall when I do a jump at 70mph after this mod.

Then I can officially tell the over-thinkers to kiss my a**. :butthead:

 

[1970Duster]

Paracitic loss for the 200R4 is 25-30 HP. Just something to think about.
Oh and a 904 uses 25 HP. So I was wrong, the 200R4 uses the same or just a tad more HP to be powered but you gain that overdrive.

 

[LJS30]

Well gentlemen it's looking like it's between the Gear Vendors and the 200R4.

 

[Tjfly4pay]

As far as that torsion bar mount, I think people are wayyyyyy to sensitive about cutting it out. Especially with the use of a 1/4" loop. Plus, did you see that beefy cross member everyone builds or is it just me?

That has TONS of torsional strength.

That in addition to the frame connectors your suppose to have in there negates any issues.


Or maybe I'm just a wild a**hole. Time will tell, something tells me the sky won't fall when I do a jump at 70mph after this mod.

Then I can officially tell the over-thinkers to kiss my a**. :butthead:

I will just say a few things. You calculate the bending moment of inertia of the original torsion bar support and it is amazingly strong. Now... Can someone cut it out and put NOTHING in its place??? Sure.... Will those people experience major structural failure?? Maybe, maybe not. I would say this.... The factory has 6 bolts holding the engine and transmission together at the bellhousing. Can you leave one out?? Sure. Will you have a problem?? Probably not. Could you leave out 2 bolts?? Sure. Now you are more likely to have a problem. Could you run it with only 1 or 2 bolts.... You get the idea.
The amount of twist from the torsion bars is quite incredible!!
I should go look at this 1/4 loop. Ive seen some pretty crazy replacement pieces for the factory frame support. Sure, frame connectors are good.... But they are on the outside of the torsion bar mount... Even when you triangulate to the inside, it doesn't have the resistance to twist equal to a strong box type frame above the tranny, with a connecting mount underneath the tranny like the factory setup. Overthinkers?? Who?? All I can say is... You have heard about the transmission woes, and the problems with a weak frame... I would rather be in the "OVERTHINKERS" camp, than the..... " I should have done that different" camp. That's just me. Respectfully. Todd

 

[magnumdust]

Well gentlemen it's looking like it's between the Gear Vendors and the 200R4.

IMO if you have the money/time for a built 200r4 and the adapter, and to do the minor modifications to make it fit. That's the way to go. The OD ratio would let you run some pretty steep gears on the street and keep a good highway manners.

 

[Furious65]

I still don't see the problem with an 42/46rh if you aren't trying to get max ET at the strip. For a daily driver I think it would be fine.

 

[magnumdust]

I still don't see the problem with an 42/46rh if you aren't trying to get max ET at the strip. For a daily driver I think it would be fine.

I really considered that option and i don't think there is technically anything "wrong" with it, it just doesnt fit as well as the 200r4

 

[Woods74]

From the top sticky on this forum:

Weak.... :roll:

 

[Rice Nuker]

I just cant see why installing an a833 OD would be cost prohibitive if you had patience and sourced good used parts and disassembled them for a good check out like all used parts should be. Save yourself a bundle of money and fabrication. Just pick up one part at a time and be sure it is a decent quality part by making informed careful purchases. In a year, you will have a nice 4 speed overdrive kit ready to slap in. 300 hp will not need fancy or new parts. Just decent quality and not badly worn. Reman clutch / pressure plate from napa. Napa throw out bearing. Your factory drive shaft will work fine. As long as you dont abuse it hard, it will last years. Your rear end will die fairly quickly if you have a 7.25.

I put an a833 OD (cast iron case from what I remember) in a volare which was originally 318 /2bbl /904 /2.76 7.25. Went 4bbl dbl pumper 650 holley / rpm intake / 360 cleaned up J heads /mild crane cam /headers /a833OD /3.91SG. Every part was used but the lifters , the clutch/pressure plate and generic 2.5" duals dump at rear end. Original drive shaft. It ran very great and fun. I abused the living heck out of that setup and finally broke a couple U-Joints here and there. I mean dumping the clutch constantly at 4K, powershifting at 6200 all the friggin time every day. I was crazy. If you don't abuse a setup made from basic parts you could have a smooth machine for years.

To install a 4 speed hump with no fancy tools: get a new hump for 65 bucks online at one of the 50+ places that sell them (brewer's is good quality from my experience), draw a line on the floor pan around the hump edge, get a jigsaw with a metal blade and some extra new blades and carefully cut 1/2" smaller than the new hump line on the floor board (dont cut thru your crossmember). Sand the floor pan to bare metal 1/2" wide around the opening, sand the hump clean to metal on the bottom contact area. Use steel panel adhesive (follow its procedures) and glue the thing in place. It will take you a few hours and will require no fancy skills, no fancy machinery, only patience. Then the only other mod is the small reinforcement piece to your inner fender for the Z bar pivot and a little hole for the clutch rod.

Guys, is this not good advice here? I mean heck, lots of people have built great hot rod machines out of used parts which were designed to go right into our A bodies.

 

[rednesss]

I cut mine out and replaced it with some 1/4" x 4" flat stock that I bent into a U shape on a friend of mine's press break.

[/IMG]

Then I welded up a simple cross member that mounts to my frame connectors.

[/IMG]

Personally I don't have any worries about the torsion bars or the strength of the crossmember.

 

[Tjfly4pay]

Using the 1/12 B(H^3) formula for calculating the bending moment of inertia, it has no torsional rigidity. .00. For the variables, I used a 2" wide .25" thick solid steel. A flat piece of steel will twist, angle iron will twist less, and an "I" beam even less. Just FYI.
I'm sure yours will be fine... You will probably never have a problem.
All the best!!! Todd

 

[Woods74]

Using the 1/12 B(H^3) formula for calculating the bending moment of inertia, it has no torsional rigidity. .00. For the variables, I used a 2" wide .25" thick solid steel. A flat piece of steel will twist, angle iron will twist less, and an "I" beam even less. Just FYI.
I'm sure yours will be fine... You will probably never have a problem.
All the best!!! Todd

How about something like this?

We're making room for an A500 out of a dakota 318 pickup truck. You have to fix the cross member to get it to fit. A lot of people say you have to cut the floor, which is not the case. Took 3" wide 3/16 flat metal and shaped it to where it is flat against floor. Cut out center of cross member that goes up into the hump. Took 1/2" wide 1/8th thick metal and tack welded to the side of the 3" piece. We took a torch and heated up the 1/2" wide piece and shaped it. Until it was shaped all the way around. Did it on both sides, front and back. Heliarced inside and outside. Welded that back into the floor, it clears the transmission now without cutting the floorpan.

We tied the frame together to give more support. If you don't want to tie it together, at least go in front of cross member and put a piece of 2x3 tubing at a 45 degree angle to the frame for extra support for the cross member. We choose to tie the frame together properly. On an ebody car it is a tremendous help. These cars are so short and so wide, they tend to twist/flex.

From another post:

If that sucks, I'll just leave the 1/4" bend out, less work anyway.

 

[Revhendo]

I just cant see why installing an a833 OD would be cost prohibitive if you had patience and sourced good used parts and disassembled them for a good check out like all used parts should be. Save yourself a bundle of money and fabrication. Just pick up one part at a time and be sure it is a decent quality part by making informed careful purchases. In a year, you will have a nice 4 speed overdrive kit ready to slap in. 300 hp will not need fancy or new parts. Just decent quality and not badly worn. Reman clutch / pressure plate from napa. Napa throw out bearing. Your factory drive shaft will work fine. As long as you dont abuse it hard, it will last years. Your rear end will die fairly quickly if you have a 7.25.

I put an a833 OD (cast iron case from what I remember) in a volare which was originally 318 /2bbl /904 /2.76 7.25. Went 4bbl dbl pumper 650 holley / rpm intake / 360 cleaned up J heads /mild crane cam /headers /a833OD /3.91SG. Every part was used but the lifters , the clutch/pressure plate and generic 2.5" duals dump at rear end. Original drive shaft. It ran very great and fun. I abused the living heck out of that setup and finally broke a couple U-Joints here and there. I mean dumping the clutch constantly at 4K, powershifting at 6200 all the friggin time every day. I was crazy. If you don't abuse a setup made from basic parts you could have a smooth machine for years.

To install a 4 speed hump with no fancy tools: get a new hump for 65 bucks online at one of the 50+ places that sell them (brewer's is good quality from my experience), draw a line on the floor pan around the hump edge, get a jigsaw with a metal blade and some extra new blades and carefully cut 1/2" smaller than the new hump line on the floor board (dont cut thru your crossmember). Sand the floor pan to bare metal 1/2" wide around the opening, sand the hump clean to metal on the bottom contact area. Use steel panel adhesive (follow its procedures) and glue the thing in place. It will take you a few hours and will require no fancy skills, no fancy machinery, only patience. Then the only other mod is the small reinforcement piece to your inner fender for the Z bar pivot and a little hole for the clutch rod.

Guys, is this not good advice here? I mean heck, lots of people have built great hot rod machines out of used parts which were designed to go right into our A bodies.

I totally agree with you on this. With one exception. Whereas I really enjoy a manual shift car, my left knee just doesn't go along with the program anymore. Were I going stick again, this would be my first low buck choice. The Viper trans would be my ultimate choice.

For an AOD, the 200 would be my first low buck choice. I've driven a bunch of them and like the performance and the way they shift. My ultimate would be a built 4l60. Laptop tuneable, stout enough for what I need and a relatively small package. Were I going brute power, it would be the 4l80.

As far as the floor brace for the T bar crossmember, a little notching and boxing for the 200 ain't so bad and you won't lose any integrity if done right. You do know that you can add on top of the floor pan also, right?

 

[Revhendo]

Or maybe I'm just a wild a**hole. Time will tell, something tells me the sky won't fall when I do a jump at 70mph after this mod.

The jury is still out on what type of hole you are, but I want picks and video of that jump..... :blob:

 

[dart6]

perhaps a mild 318 is underpowered to make the most of the 518, i intend to run a 408 stroker in my 70 sat

 

[Revhendo]

Anybody have a chart to show how much power it takes to work these transmissions?
Isn't it called a Kilgore rating or something like that?

 

[Powerflite]

Welding that 1/4" plate to the tunnel floor is where most of the strength comes in because it is being supported by the floor. The thickness of the material does very little and is mostly extra weight. It is also difficult to get good weld penetration when you weld dramatically different thicknesses together. In my opinion, you should just use the upper tunnel floor itself and box in a 1/2 - 5/8" tall channel with a more reasonable 1/8" plate. That would likely be stronger without all the unnecessary weight.

 

[inkjunkie]

Anybody have a chart to show how much power it takes to work these transmissions?
Isn't it called a Kilgore rating or something like that?

The bottom picture of post 119 is of my car. The fab guy that did that has told me that he has done a few cars with the t-bar triangulated back into the sub-frame connectors with no troubles yet. In my case one way or the other, either with Dillinger parts or a HemiDeny k-frame I will be losing the t-bars. As to the amount of power you lose, from what little I know, that is very variable. The 4l80 is is a bit of a pig...using factory stuff. Largely because the oem t/c weighs as much as a boat anchor. But at the same time with the right parts it can easily with stand 1500 hp. I think that you just have to pick your poison. None of the od transmissions are perfect. Take a GV unit behind any dinosaur 3 speed. If you have a loose convertor you may end up running around with the convertor slipping. Maybe not the case with a low powered dd but very possible with a high powered street car, spoke with Lenny at Ultimate Convertor a while back and he was fighting that very problem with a customer and his HEMI Dart. When the convertor was loose enough to perform at the strip it would slip on the street while the od was engaged. When it was tight enough to not slip on the street it was to tight to allow the car to launch well at the strip. Solution, a lock up convertor. Which opens up the need to do some cutting on the car. Just like most things in life, there is no one "right" answer. No matter which way you go you will always run into the nay sayers. Such is life.