42RH Swap: '80 Volare

Oldiron440

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Funny I was just talking to them today about a converter, I realized that I was dealing with the wrong person when he said he'd have to talk to someone who knows Chrysler and get back to me. I called ATI.
 

BudW

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Thank you for the pictures!

That doesn’t look too hard to modify the lower transmission crossmember.
What about the upper crossmember (the one welded to floorpan)? Any changes made to it?
BudW
 

BudW

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A500s are 2.74-1.54-1.00, same as A999s and some A998s
A518s are 2.45-1.45-1.00, same as A727s, A999s ,and some A998s
Fixed to say:
A500s are 2.74-1.54-1.00, same as A999s and some A998s
A518s are 2.45-1.45-1.00, same as A727s, A904s ,and some A998s
BudW
 

BudW

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it would have been nice if Mopar had a big block OD.
I had thought about doing this, more than a few times.

The only reason I'm not considering it is because the only thing connecting the bellhousing to the transmission case (as well as 500 HP/500 foot pounds of torque – or whatever it might actually be) is 6 (or 7, I forget) tiny screws that are ¼” in diameter.

I have twisted those front pump screw heads off before (it doesn't take much), during transmission overhauls - so I just don’t want that to be my “weak link”.
If there was a better way of attaching the bell to the case – then I would be driving one right now.

Also, I don't know of anyone personally using one - and in actuality, the 6 (or 7) tiny screws might be strong enough for my application – only I just don’t see how.
BudW
 

BudW

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JustWondering,
In 1987 (or 1988), Chrysler came out with an overdrive automatic transmission, for pickups, vans and Jeeps.
Basically what Chrysler did, was they added the overdrive onto the tail section of transmission.

The transmission you have in your 5th Ave looks like the first one below, and is called A999 (which is mostly the same as A904, A998, or newer versions of same transmission is called 30RH, 31RH, 32RH).

The newer versions, the first digit is the number of speeds (3), second digit is the strength (0, 1, 2 ~ 9), third digit is which direction in vehicle (in this case North to South) and forth digit is Hydraulic vs Electronic (n this case Hydraulic).
A904.jpg

The four speed version is called A500 (or newer versions are called 40RH, 42RH, 40RE, 42RE & 44RE) and looks like this:
A500.jpg

The red arrow is where the overdrive is located at. The blue arrow is where the different transmission mount attaches.

The heavy duty transmissions called A727 (or 36RH or 37RH) for 3-speed, or 4-speed version is called A518 (or A618, 46RH, 46RE, 47RH or 47RE), and looks like:
A727 vs A518.jpg

The A518 is top, 727 is bottom.

There is a guide that describes this a bit better at our forums sister site http://www.forbbodiesonly.com/moparforum/threads/your-guide-to-the-727-904-transmission.17287/
Mopar_trans.jpg

This chart was taken from that site and modified a bit. The distance from engine to case/tailhousing flange (red line) is the same on all A904, A998, A999, A727, A500 and A518’s.
The same also applies to engine to transmission mount on A904, A998, A999 and A727 – but is different on 4-speeds (A500 and A518).


Our cars never did come with overdrive (or with fuel injection) but should have. It would make a lot of modifications a lot easier, if they did.

On pickups and vans, it is very easy to change one over from 3-speed automatic to a 4-speed automatic, and either change the transmission mount and/or the crossmember.

“I have been told” (but no first-hand experience on this) the tailhousing section of the overdrive transmissions (where the overdrive is located at or red arrow in above picture) is too large in diameter to fit in the floor pan transmission tunnel section – without modifications to floor pan first.
I hadn’t tried this modification yet, so have no first hand knowledge about it.
I know the transmission crossmember has to be modified for the overdrive transmission to fit (which pictures in above posts show that).

I don’t seen any notes in this thread about modifying the floorpan or the upper part of transmission crossmember (welded to frame) – but it appears the upper crossmember might have been trimmed or cut to allow for the larger diameter tailhousing to fit, possibly (but could be mistaken).
20180129_164315.jpg


This area is not a high stress area, like the older Chryslers are – so some trimming of parts shouldn’t matter a lot. That said, if trimming/cutting is required – it would be nice to mention that in the post – for other members here who is thinking about doing the same thing.


I like overdrives – especially ones that are a direct bolt in. That way you have a decent differential gear (for take-off power) as well as decent (better?) fuel mileage.
BudW
 

mchartier105

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JustWondering,
In 1987 (or 1988), Chrysler came out with an overdrive automatic transmission, for pickups, vans and Jeeps.
Basically what Chrysler did, was they added the overdrive onto the tail section of transmission.

The transmission you have in your 5th Ave looks like the first one below, and is called A999 (which is mostly the same as A904, A998, or newer versions of same transmission is called 30RH, 31RH, 32RH).

The newer versions, the first digit is the number of speeds (3), second digit is the strength (0, 1, 2 ~ 9), third digit is which direction in vehicle (in this case North to South) and forth digit is Hydraulic vs Electronic (n this case Hydraulic).
View attachment 28195
The four speed version is called A500 (or newer versions are called 40RH, 42RH, 40RE, 42RE & 44RE) and looks like this:
View attachment 28196
The red arrow is where the overdrive is located at. The blue arrow is where the different transmission mount attaches.

The heavy duty transmissions called A727 (or 36RH or 37RH) for 3-speed, or 4-speed version is called A518 (or A618, 46RH, 46RE, 47RH or 47RE), and looks like:
View attachment 28197
The A518 is top, 727 is bottom.

There is a guide that describes this a bit better at our forums sister site http://www.forbbodiesonly.com/moparforum/threads/your-guide-to-the-727-904-transmission.17287/
View attachment 28198
This chart was taken from that site and modified a bit. The distance from engine to case/tailhousing flange (red line) is the same on all A904, A998, A999, A727, A500 and A518’s.
The same also applies to engine to transmission mount on A904, A998, A999 and A727 – but is different on 4-speeds (A500 and A518).


Our cars never did come with overdrive (or with fuel injection) but should have. It would make a lot of modifications a lot easier, if they did.

On pickups and vans, it is very easy to change one over from 3-speed automatic to a 4-speed automatic, and either change the transmission mount and/or the crossmember.

“I have been told” (but no first-hand experience on this) the tailhousing section of the overdrive transmissions (where the overdrive is located at or red arrow in above picture) is too large in diameter to fit in the floor pan transmission tunnel section – without modifications to floor pan first.
I hadn’t tried this modification yet, so have no first hand knowledge about it.
I know the transmission crossmember has to be modified for the overdrive transmission to fit (which pictures in above posts show that).

I don’t seen any notes in this thread about modifying the floorpan or the upper part of transmission crossmember (welded to frame) – but it appears the upper crossmember might have been trimmed or cut to allow for the larger diameter tailhousing to fit, possibly (but could be mistaken).
View attachment 28199

This area is not a high stress area, like the older Chryslers are – so some trimming of parts shouldn’t matter a lot. That said, if trimming/cutting is required – it would be nice to mention that in the post – for other members here who is thinking about doing the same thing.


I like overdrives – especially ones that are a direct bolt in. That way you have a decent differential gear (for take-off power) as well as decent (better?) fuel mileage.
BudW

Zero problems with floorpan clearance on our cars (2 door F body's at least) but the upper crossmember needed to be cut/grinded significantly to allow the tailshaft to sit in the correct position. I would say probably about 3/4 of it needed to come out, the piece I left that you can see in the picture is about 1/2" of crossmember that I left in to keep the floorpan braced.
 

Justwondering

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So you are saying that you have a DIY way to modify the frame and bracing so that the new/different transmission sits correctly under the car - somewhat offcenter - and somewhat longer than the original transmission
And
you want the new/different transmission so you can change the RPM to gear selection in order to optimize the highway cruise or the initial start up.
Optimizing the highway cruise means you can reduce the wear on the engine due to reducing the RPMs needed to push the car forward-- the different transmission and gearing lets you obtain that efficiency. Reducing the RPMS at cruise would also buy you a reduction in noise from the engine.

If all that is correct, then my last question is how does the new gear box get activated? Is there a separate lever to engage it or is there something inside the new transmission that activates it when needed?
 

AJ/FormS

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So you are saying that you have a DIY way to modify the frame and bracing so that the new/different transmission sits correctly under the car - somewhat offcenter - and somewhat longer than the original transmission
And
you want the new/different transmission so you can change the RPM to gear selection in order to optimize the highway cruise or the initial start up.
Optimizing the highway cruise means you can reduce the wear on the engine due to reducing the RPMs needed to push the car forward-- the different transmission and gearing lets you obtain that efficiency. Reducing the RPMS at cruise would also buy you a reduction in noise from the engine.

If all that is correct, then my last question is how does the new gear box get activated? Is there a separate lever to engage it or is there something inside the new transmission that activates it when needed?
You got it.
Engagement is by electric shift, in this case. Per post #1, he's using toggle switches. You can do that using the older models, before computer shift.
 

Justwondering

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And because it is electric shift, our cars don't have the 'smarts' to be able to tell it to shift into overdrive?
 

Justwondering

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FYI -- pulled the instrument cluster (4 screws) and unplugged the old cluster, plugged in the new cluster, reinstalled the 4 screws and the plastic surround on the dash and Viola' ... I now am down to just the seats, weather stripping, and speed sensor before I move on to the dents/paint in the Silverado.
 

mchartier105

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So you are saying that you have a DIY way to modify the frame and bracing so that the new/different transmission sits correctly under the car - somewhat offcenter - and somewhat longer than the original transmission
And
you want the new/different transmission so you can change the RPM to gear selection in order to optimize the highway cruise or the initial start up.
Optimizing the highway cruise means you can reduce the wear on the engine due to reducing the RPMs needed to push the car forward-- the different transmission and gearing lets you obtain that efficiency. Reducing the RPMS at cruise would also buy you a reduction in noise from the engine.

If all that is correct, then my last question is how does the new gear box get activated? Is there a separate lever to engage it or is there something inside the new transmission that activates it when needed?
Larger yes, somewhat off centre, not really. It's pretty straight inline with the motor and rear end and all that's correct, to answer your last question, I have it set to a toggle switch on my dash for OD and lockup, but I'll be moving to pressure switches to control it automatically once money permits.
 

BudW

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And because it is electric shift, our cars don't have the 'smarts' to be able to tell it to shift into overdrive?
The Chrysler 4-speed automatic transmissions are computer controlled (either a little or a lot).
The earlier ones (’87 to ~95) can be adapted to do its thing automatically using pressure switches and about two hours of wiring and such (ie: no computer usage).
The newer ones (including the 8-speed automatics used today) usually require a computer to do their thing – which can still be done but takes more parts and more labor to get working.

For normal driving – like what you and/or your husband do, it doesn’t make any sense to go with an overdrive transmission.

The people who want their cars to get to speed from a stop, um, significantly faster, are the ones interested in an overdrive.

Justwondering your ’87 5th Ave has a 7¼” rear differential with 2.2 ratio gears (exactly like my ’86 5th Ave has, currently).
Right now, my ’86 5th Ave travels the ¼ mile (from a stop) in 21.1 seconds when throttle is wide open (WOT) – which is not very impressive. See thread https://www.forfmjbodiesonly.com/classicmopar/threads/performance-meter.5547/page-2 post # 29, for more details.

My ’77 Volare station wagon is identical to 5th Ave in almost all aspects – except for rear differential gear ratio. It has a 3.21 gear ratio. Because of that, it currently does the ¼ mile 17.6 seconds (same thread as above, but post # 30) at WOT – which is a big difference (same horsepower engine, same transmission, roughly same weight vehicle, etc.).
Also, both cars get roughly the same gas mileage city or highway.

If I was to install a 3.91 gear ratio, into either car, it will snap your neck at a takeoff – but wouldn’t be advisable for highway usage (now fuel mileage on highways will start going downwards and engine noise might be unbearable).

Now, if a person had 3.91 gears and an overdrive transmission – now you got the best of both worlds (neck snapping acceleration and good fuel mileage). It will also make car a lot quieter at highway speeds (great for trips).
There are reasons to want to install overdrive transmissions – but it is also, not for everyone.

Currently:
My goal for my ’86 5th Ave is to ditch the 2.2 gears in favor for 2.94’s (or 3.23’s if I can find an 8¾” differential, first).
For the wagon – if I decide to install big block into it, I will also convert it to a manual transmission. A Tremec 5-speed (with overdrive) or a Magnum 6-speed (with two overdrive gears). I’ll most likely be changing the differential gears to a 3.55 or lower ratio (which means a higher number).
For my '97 diesel pickup – it currently has 3.54 gears in it (Dana 80). It also has an overdrive (NV4500-HD) which I drive mostly on highway. I keep trying to shift it into 6th speed (which it doesn’t have). For it, I want either a Gear Venders unit (http://www.gearvendors.com/dmanual.html) which is $3,100 (US) – too steep for me, or to find a higher gear ratio for it (lower numerically).
My diesel is almost red-lined (3,000 RPM) at 80 MPH (the current speed limit for Oklahoma, on turnpikes is 75 MPH). There are not a lot of gear ratio choices available for the Dana 80 – so Gear Venders might be the way to go – but that is a lot of money for a little gain.

Hopefully this helps,
BudW
 

BudW

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It woulda been nice if Mopar had made a SBM manual 5-speed with tight splits, and a drop-down od Fifth, as a direct fit to where the A833 had been.
I might be getting my hands on a few 5-speeds soon – and may have more information on them shortly.
My dad has been rebuilding manual transmissions for a long time and is “cleaning house”. I just need to drive 10 hours and get what he has (which might be NV1500, NV2500, NV3500 and/or others – not sure, yet).

I’ll have a better answer on this matter in a few months.
BudW
 

AJ/FormS

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If you put the GVOD behind an A998 with the wide ratios, you can use it as a splitter.
2.74-2.14-1.54-1.20-1.00-.78od. GVOD in red, and splits of
.78-.72-.78-.83-.78
If you use this with 3.55s you get road gears of 9.73-7.60-5.47-4.26-3.55-2.76 and
65=2240 with 27s.
The 9.73 starter gear, means the equivalent of 3.97 gears with a 904/727. And turns a 318 into a real fire-breather.
If you plot these ratios as mph versus rpm, you can see that it might be beneficial to short-shift the 1-1od, then ram her along, and the short 2-od to direct split is 935rpm at a 5500 rpm shift. This would keep your engine within 470rpm on either side of the power peak from 70mph to107mph. That's a long time sitting that close to peak.
You could gear the chassis to use 5 ratios in the qtr...........yeah; five!.... and even 4.30s are equivalent to 3.35s with the od. It wouldn't take much motor to get into the mid 12s

I wanted to try this and called GearVendors, but they wouldn't sell me an adapter; Unless I first sent them my old A833 adapter back. That's whack! Or for another $2400,(in 2004), I coulda had a second GV unit. No thx I said.
I wanted to set this up for my winter motor; a stock 73 318 with a 4 bbl and the TTIs which have always been in the chassis......and 4.30s which I already had as well.
I think I would really like that. The things I never liked about automatics are; the huge rpm drops at the shifts, especially the 1-2 shift, and the resultant very wide powerband requirement.Split shifting when flogging it,and not, when not flogging it, IMO would be the best of both worlds. Then I would detune/retune my engine or even downsize it, to take advantage of the new gears.
I mean, I'm happy with the power it takes to go 105 in the qtr with 3 gears. I could be happy doing that with 5,lol. And with the new higher average hp, I bet I could give up a cam-size, and gain some low-rpm torque, allowing a smaller engine. I've always had a hankering to do this with 273/318 in a lightweight A-body.
 
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slant6billy

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Having an "overdrive" gear is a Godsend. Ever ridden a 2 stroke dirtbike? Imagine your morning commute for 20 minutes, 40 minutes or worse with full throttle on a 2 stroke bike over the river and through the woods. By the time you get to work, your eye balls are loose in your head (blurry vision), loose fillings and rattled nerves. The overdrive cures all that. I need an overdrive in my 79 Volare badly. 4000 RPM at highway speeds and way worse at 80mph. I drive it to work every once in a while, but I'm completely useless for the day to think clearly. All my ability to deal with difficult people is gone. So as a purpose to not beat the daylights out of folks, I'll drive the eco box and arrive unrattled.
 

Justwondering

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no neck snapping for this couple, I agree.
I'm assuming you have to adapt the size of the 'connecting rod' or whatever the term is for the rod that goes from the transmission to drive line? Oh Lord I should have done some reading so I'd sound like I know what I'm talking about...lol

This sounds like an interesting puzzle with potential for greatness when done. But its an awfully heavy part of the car and buried underneath. You'd really have to have a solid place to work on things and it would seem, a concentrated effort to stay organized with all the bits and pieces in play.

I bow to your persistence and knowledge as well as your courage to contemplate the project.
 
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