Gear Vendors or swap for performance 5 spd OD?

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Steve Mcbean

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Hello, fellow Mopar freakazoids.

So, the 318 in my 71 Demon has minor perf. upgrades, but am preparing for more. I have a 3 spd 904 Torqueflite and was thinking of adding an GV unit instead of upgrading the tranny. The price for the GV unit is $2850 while a 5 spd performance tranny from transmissions.net runs around $2600. The rear end will be upgraded from 7.25, to 9 inch or so. My trusty mechanic recommends upgrading the tranny will be cheaper, but I don't see how when the tranny price is close to the GV price and labor hours and modifications seems much lower installing the GV, not to mention the GV allows for 6 speed and gear splitting. I am assuming this question has been asked a bazillion times?
 
My 2 cents is to get a chevy 4 speed auto

While gear-splitting sounds exciting, it doesn't work particularly well with a stock-cam 318/904, on the street.
The 904 ratios are 2.45-1.45-1.00
The GVod is .78. Combining them you get
2.45-1.91-1.45-1.13-1.00-.78od.. The splits are
.78-.76-.78-.88-.78

With the od, you are likely gonna shoot for a 2.76 final drive so 2.76/.78=3.55s in the back.

Minor performance upgrades, usually means still running the stock cam. Therefore, the power will peak at about 4000rpm, and your shift rpm could be 4400.
Ok lets convert this to mph at WOT. Assuming 27" tires;4400 is;
38 in first,
48 in first-over,
60 will be 4140@ 8% slip, perfect
64 in second,
82 in second-over,
93 in direct.
93 is gonna take you ~16/17seconds, so you better choose your spot carefully
64 will be your everyday cut-off, so you are paying $2850 to split one gear, and for the overdrive cruiser gear.
The thing is this; The stock cam 318 loses torque so rapidly after 3000, that the horsepower curve is sorta flat from there to the peak. So splitting that gear may possible gain you something, in the zero to 60mph contest, but my money is on about nothing
The other problem is that the GV requires a power-cut to outshift, which you would have to do at 48 mph to get into Second. So very possibly, probably, any time you gained on the in-shift, you are gonna lose it all, on the outshift.
So, honestly, the GVod is just gonna end up as a novelty, and a cruiser gear. $2850 is a lotta coin for just a cruiser gear.
IMO
that money would be better spent on a 5.9 Magnum and leave whatever gears are in your car, but install a 2800TC.

Maybe you already have 2.76s
The 5.9 at 2800rpm, will put down about the same or probably a lil more power on the launch, than your LA318 with 3.55s, and it will hit 60 at ~5300 at the top of first gear,probably dwarfing the 318's ET. 5300 is probably a lil high, but just put some appropriate valve springs on her and letRbuck.
On the shift into Second at 60, the 5.9 is all set to run to 93mph @5500
And of course , it will cruise at the same Rpm, as the 904/GVod.
So this is IMO, a better solution, if I'm reading you right.

Now, why did I recommend the 4L60 /700R4 GM trans?
Cuz the ratios are
3.06-1.63-1.00-.696od, and the splits are
.53-.61-.70 nice progressive splits for the 318 .
Again for a final drive of 2.76, this would require 2.79/.696=3.91s, booyah

Now lets compare this at the rear wheels;
first the 904/3.55/GVod; then the 4L602/3.91s.
1).. 8.70-5.15-3.55-2.77
2) 11.96-6.37-3.91-2.72......... Ok but your still thinking splitting so;904/3.55
1B).. 8.70-6.79-5.15-4.02-3.55-2.77, but hang on; this GM is gonna hit 60 @5130 @ 8% slip, That is too much for your stock-cam 318. In third it will be 3150*, too low. So we need different gears to be fair. The closest gears are 5.15/1.63=3.16 so round to 3.23s and now the numbers look like
2B) 9.88-5.26-3.23-2.25 whoaaa. Compare this to the 904/3.55s
1) . 8.70-5.15-3.55-2.77
Look at that! Both first and second are still better. We lost 10% in third, but man-oh-man, 65=1817 rpm, real nice for the factory 318 cam; you should be able to get about 7 million mpgs,lol.
What do ya think about that!
And even better,the GM has a loc-up TC.

And finally; yes you can get adapters to put that Chebby lump into your Mopar.
The Mopar has a deeper od (.69). and the ratios of the A500 are tighter. Which in theory would be a better choice for your 318, but making it fit is a PITA.
The ratios are 2.74-1.54-1.00-.69
for a cruiser of 2.76 this would require 2.76/.69=4.00 rear so lets round to 4.10s.
On the road then this would be;
4) 11.23-6.31-4.10-2.83.. compared to the GM
2) 11.96-6.37-3.91-2.72.. see the edge in third gear there? just where the 318 needs it. The penalty is 80 more cruising rpm with the 4.10s. And the A500 also has a loc-up. I did not correct these to a 5.15 second gear, cuz I don't see a point in gears that low for cruising, or that high to blast off with. A better idea would be to up-came the 318.

My money is on dropping a junkyard 5.9 in there with a4bbl and a 2800TC. And leaving the rest alone........... 4now,lol.

done
 
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My 2 cents is to get a chevy 4 speed auto

While gear-splitting sounds exciting, it doesn't work particularly well with a stock-cam 318/904, on the street.
The 904 ratios are 2.45-1.45-1.00
The GVod is .78. Combining them you get
2.45-1.91-1.45-1.13-1.00-.78od.. The splits are
.78-.76-.78-.88-.78

With the od, you are likely gonna shoot for a 2.76 final drive so 2.76/.78=3.55s in the back.

Minor performance upgrades, usually means still running the stock cam. Therefore, the power will peak at about 4000rpm, and your shift rpm could be 4400.
Ok lets convert this to mph at WOT. Assuming 27" tires;4400 is;
38 in first,
48 in first-over,
64 in second,
82 in second-over,
93 in direct.
93 is gonna take you ~15seconds, so you better choose your spot carefully
64 will be your everyday cut-off, so you are paying $2850 to split one gear, and for the overdrive cruiser gear.
The thing is this; The stock cam 318 loses torque so rapidly after 3000, that the horsepower curve is nearly flat from there to the peak. So splitting that gear may possible gain you something, in the zero to 60mph contest, but my money is on about nothing
The other problem is that the GV requires a power-cut to outshift, which you would have to do at 48 mph to get into Second. So very possibly, probably, any time you gained on the in-shift, you are gonna lose it all, on the outshift.
So, honestly, the GVod is just gonna end up as a novelty, and a cruiser gear. $2850 is a lotta coin for just a cruiser gear.
IMO
that money would be better spent on a 5.9 Magnum and leave whatever gears are in your car, but install a 2800TC

more coming
Thanks, but like I mentioned, I am "preparing" for more performance upgrades to the motor, including performance heads and cam and EFI. I also mentioned the rear end gear would be upgraded.
 
Depends on what your looking to accomplish. I have a car that I converted to a 5 speed and one that has a 727 and a GVOD. If I had it to do over again on the 5 speed car I would have bolted the GV behind the 833. Why? Less to no mods to the car that take time and money.
The gear splits sound nice but under race conditions I doubt they will work. I mainly just use my GV as an overdrive gear.
 
Depends on what your looking to accomplish. I have a car that I converted to a 5 speed and one that has a 727 and a GVOD. If I had it to do over again on the 5 speed car I would have bolted the GV behind the 833. Why? Less to no mods to the car that take time and money.
The gear splits sound nice but under race conditions I doubt they will work. I mainly just use my GV as an overdrive gear.


Less to no mods? AJ/FormS, said they had to cut into the hump and reaarange the exhaust. That was a few years ago, i think. Did you have to do that? My goal is to save money on labor and equipment and prevent destruction on my car while enjoying OD with a 400 hp car. Splitting gears isn't essential.
 
I have an E-body so not sure how different the A is going to be but can’t imagine it’s that different in the area I had to work on. I only had to make two small dimples in the hump one where the speedometer setup attaches to the unit and one where the top of the unit met the tunnel. I have a TTI exhaust so they make a special H pipe for the GVOD setup as you will have to move the “H”.
 
I have an E-body so not sure how different the A is going to be but can’t imagine it’s that different in the area I had to work on. I only had to make two small dimples in the hump one where the speedometer setup attaches to the unit and one where the top of the unit met the tunnel. I have a TTI exhaust so they make a special H pipe for the GVOD setup as you will have to move the “H”.

I have TTIs as well no H pipe. Here's the undercarriage of mine. Do you think the GV will fit without cutting?

IMG-20200324-WA0001.jpg


IMG-20200324-WA0014.jpg
 
AJ/FormS, said they had to cut into the hump and reaarange the exhaust.

Not quite right.
When I got mine, GV only had the long-tail,B/E adapter. To use it, I had to shave a couple of the mounting bosses off the front shifterpad, to clear the tunnel. After that I mounted the unit and jacked it up into the tunnel to see where it touched, marked it well, and took the unit back down.
Then out game the BFG, and I took care of business.

So next, I had to drop the rear mount a tad. I am using the Spool mount, so this was just a matter of elongating the holes for the thru bolt.
Then I had to cut the X-over out, patch the pipes,shorten the driveshaft, and fabricate a new shifter adapter.

But I gotta tellya, cutting that x-over out, changed the low-rpm torque big-time; I wouldna believed it. I spent the rest of that summer hunting for it, but never got much back. In the end I called Passon, and Jamie hooked me up with the Commando guts, a HD longshaft, and one of his aluminum boxes. That new 3.09low is a 16% increase in TM, over the old 2.66; and that did it, in spades.

Now I gotta tellya another thing;
The new 1-2 split is big enough to split nicely.
The ratios are 3.09-1.92-1.40-1.00..
I run 3.55s, so out the back, so the ratios are 10.97-6.82-4.97-3.55
The GV is a .78 splitter, so adding it in, I get;
10.97-8.56-6.82-5.32-*** (GV in red), with splits of .78-.80-.78 Shazzam!
Those are some really tight splits. Tighter even the the T/A 2.47 low box.
Those 4 ratios get me to 93 in the 1/8 at 6150rpm@3467 pounds/900ft.
That's one pull on the big stick, and in-out-in on the button.
My engine is nothing real fancy, (see my sig below), with a 230*.050 cam.
The Wallace calculator makes 93mph to be 433 hp. Yeah right.
My power peak is around 5300 with that cam, and the outshift should probably be around 5600.
With an average .78 split, the Rs would drop to 4370 for a powerband requirement of 1230rpm.
In comparison, the 2.66 box will drop 1510; Is 280rpm a big deal; IDK.
Two of those shifts are powershifted just like an automatic.I think that is a bigger deal. And of course my box is slick-shifted in both second and third, so good luck finding a break in the blackies.
The hard part is outshifting the GV, while simultaneously grabbing second. The GV is not supposed to be under load when coming out, and it has a ever so slight hesitation from the time you push the button until something happens at the GV clutch. The hesitation varies with driveshaft rpm. So yeah, it's tricky, and I don't think a guy could ever be consistent with it, but it sure was fun.

I love this combo for it's versatility. It is way better than when I was splitting the A833od box. I thought I was pretty smart when I put that together. I drove it for two or three years, trying every rear gear in my arsenal from 2.76s to 5.38s with a couple of holes in the line up, but I could not cover all the bases all of the time. Plus I kept breaking that fragile mainshaft od gear. In the end I pulled it outta there for the Commando set-up I have now. Yeah I slick-shifted second in that box too,lol.

The problem with that A833od box,
IMO
is not the wide splits per se, but that to get second gear where i wanted it to be, first was too deep or not deep enough.
I was trying to run outta rpm at 60mph.
With a 5500 rpm shift and 27inch tires, this takes an overall gear of 7.37.
So the rear gear requirements are;
in first over it is 3.06; In second it is 4.41; In second over it is 5.66
So 4.41s rounds to 4.30s and I installed those.
Now, tooling around, 30mph is ;
2676 in 1.67 second gear, and downshifting gets me 4950 in 3.09low.
And therein lies the problem.

At 2676 that 367 of mine is not particularly lively, and 4950 is is just 450 rpm to the shift. So that just never worked for me. I pulled and sold the 4.30s.

the Commando in comparison;
With 3.23s, I hit 60 in first-over at 5800, and
30 is 2310 in 1.92 second, and downshifting gets me 3710 in 3.09low, just around the torque peak. Very nice.

The starter gear is now , a sane 9.98, compared to the od box of 13.29.
And 65 is now 2240 with the Commando/GVod, compared to
1980 with the od/od combo,which was too low for my 230* cam.
In the end I installed 3.55s, for that magic 93mph run. They have stayed in there ever since.
 
Do you think the GV will fit without cutting?
That looks tight. I think it might fit, but I also think you're gonna cook the oil, better get the model with the deep sump. Personally, I would move the pipes for cooking room.

My goal is to save money on labor and equipment and prevent destruction on my car while enjoying OD with a 400 hp car

I'm not sure what your thinking is; $2850 is a lotta outlay that will take many many years to pay back.
A 400hp 360 is not that pipey. It will easily pull 3.23s or even less. Especially with an A999 which has ~12% more torque multiplication in first, and 6% more in second.
If you have a 360 making 400 hp; this means a cam of about 230/235 with matching hi-compression; and if a hydraulic lifter cam, or a worse a hydraulic roller,then you can pretty much forget about mpgs and the slower you rev it the worse it will be. That 230 cam will get better fuel economy at 2400 than at sub 2000. the 235 wants another 200rpm, but neither is any good at it anyway. The problems are threefold; the overlap, the tuned headers, and the lack of power cycle duration. You just gotta get the revs up on the hiway, high enough to get out of reversion, and that's the best you can do.

If you have a 318 making 400 hp normally aspirated, then forget about economy you will never get any. That's gonna take a really big cam, which is gonna dump pressure big time, and so require a hi stall out of the gate, and performance gears to carry it. So now you have two more economy killing factors. So yeah, in this case the GVod will get yur revs down, but it won't do a thing for economy, again because the problems are threefold; the overlap, the tuned headers, and the lack of power cycle duration.
Not in a million years would I push a 318 to 400 normally aspirated.

Have you considered the A999/ A998wide ratios and loc-up hi-stall TC?
I took mine out of a slanty case, that cost me nothing, and transferred them into a 904, for my winter-motor.. I used an old 2800TC I had laying around, but no loc-up in my case.
With 3.23s and 27s; 65=2600; and 60=2410.. badaboom! for me.
With 400hp on tap, you could actually run 2.94s and maybe a lil more stall.
2.94s are actually perfect for hitting 60 mph at the top of second gear, being 60=5470@8%slip, which is perfect for a 230/235 cam.
And 2.94s cruise 65=2374 in loc-up. also perfect for a 230/235 cam
Another nice thing about the 2.94/A999 combo is 30=1700@zero slip in second and kicks down to 3500WOT in first...... supersneaky!.
I would run this with a 360 and a 220 to 225HFT cam, or a lil bigger with a solid, and a 2800 on the 220, 3000 on the 225 , unless you tighten up the LSA .
But your engine is already built, and I haven't seen the build sheet.

Just trying to help.......
 
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I have TTIs as well no H pipe. Here's the undercarriage of mine. Do you think the GV will fit without cutting?

View attachment 1715493215

View attachment 1715493216


It’s hard to say from the pictures. I would be more concerned with the exhaust than the tunnel. Unfortunately I don’t have access to a lift to get a similar picture for you and would hate to say something would work for sure. I would think the tunnel is similar as the 727/904/833 had to fit both bodies.
Hopefully someone will chime in who’s installed one in an A.
 
Not quite right.
When I got mine, GV only had the long-tail,B/E adapter. To use it, I had to shave a couple of the mounting bosses off the front shifterpad, to clear the tunnel. After that I mounted the unit and jacked it up into the tunnel to see where it touched, marked it well, and took the unit back down.
Then out game the BFG, and I took care of business.

So next, I had to drop the rear mount a tad. I am using the Spool mount, so this was just a matter of elongating the holes for the thru bolt.
Then I had to cut the X-over out, patch the pipes,shorten the driveshaft, and fabricate a new shifter adapter.

But I gotta tellya, cutting that x-over out, changed the low-rpm torque big-time; I wouldna believed it. I spent the rest of that summer hunting for it, but never got much back. In the end I called Passon, and Jamie hooked me up with the Commando guts, a HD longshaft, and one of his aluminum boxes. That new 3.09low is a 16% increase in TM, over the old 2.66; and that did it, in spades.

Now I gotta tellya another thing;
The new 1-2 split is big enough to split nicely.
The ratios are 3.09-1.92-1.40-1.00..
I run 3.55s, so out the back, so the ratios are 10.97-6.82-4.97-3.55
The GV is a .78 splitter, so adding it in, I get;
10.97-8.56-6.82-5.32-*** (GV in red), with splits of .78-.80-.78 Shazzam!
Those are some really tight splits. Tighter even the the T/A 2.47 low box.
Those 4 ratios get me to 93 in the 1/8 at 6150rpm@3467 pounds/900ft.
That's one pull on the big stick, and in-out-in on the button.
My engine is nothing real fancy, (see my sig below), with a 230*.050 cam.
The Wallace calculator makes 93mph to be 433 hp. Yeah right.
My power peak is around 5300 with that cam, and the outshift should probably be around 5600.
With an average .78 split, the Rs would drop to 4370 for a powerband requirement of 1230rpm.
In comparison, the 2.66 box will drop 1510; Is 280rpm a big deal; IDK.
Two of those shifts are powershifted just like an automatic.I think that is a bigger deal. And of course my box is slick-shifted in both second and third, so good luck finding a break in the blackies.
The hard part is outshifting the GV, while simultaneously grabbing second. The GV is not supposed to be under load when coming out, and it has a ever so slight hesitation from the time you push the button until something happens at the GV clutch. The hesitation varies with driveshaft rpm. So yeah, it's tricky, and I don't think a guy could ever be consistent with it, but it sure was fun.

I love this combo for it's versatility. It is way better than when I was splitting the A833od box. I thought I was pretty smart when I put that together. I drove it for two or three years, trying every rear gear in my arsenal from 2.76s to 5.38s with a couple of holes in the line up, but I could not cover all the bases all of the time. Plus I kept breaking that fragile mainshaft od gear. In the end I pulled it outta there for the Commando set-up I have now. Yeah I slick-shifted second in that box too,lol.

The problem with that A833od box,
IMO
is not the wide splits per se, but that to get second gear where i wanted it to be, first was too deep or not deep enough.
I was trying to run outta rpm at 60mph.
With a 5500 rpm shift and 27inch tires, this takes an overall gear of 7.37.
So the rear gear requirements are;
in first over it is 3.06; In second it is 4.41; In second over it is 5.66
So 4.41s rounds to 4.30s and I installed those.
Now, tooling around, 30mph is ;
2676 in 1.67 second gear, and downshifting gets me 4950 in 3.09low.
And therein lies the problem.
At 2676 that 367 of mine is not particularly lively, and 4950 is is just 450 rpm to the shift. So that just never worked for me. I pulled and sold the 4.30s.


the Commando in comparison;
With 3.23s, I hit 60 in first-over at 5800, and
30 is 2310 in 1.92 second, and downshifting gets me 3710 in 3.09low, just around the torque peak. Very nice.

The starter gear is now , a sane 9.98, compared to the od box of 13.29.
And 65 is now 2240 with the Commando/GVod, compared to
1980 with the od/od combo,which was too low for my 230* cam.
In the end I installed 3.55s, for that magic 93mph run. They have stayed in there ever since.

WHew, that's a lot over my head. I feel like Tom Cruise in Days of Thunder. Don't know what you said, I just know how to drive it. Haha, seriously, I can do shade tree mechanic work, but when it comes to yall's level, I the hard stuff to my mechanic. SO, back to my original question: Swap tranny or GV?
 
I put the GV in my 67 Barracuda with the 904. 3:71 gears. The only change I made was lowering the transmission crossmember about an inch and building a new driveline. The electrical work is more serious than the mechanical work.
 
I put the GV in my 67 Barracuda with the 904. 3:71 gears. The only change I made was lowering the transmission crossmember about an inch and building a new driveline. The electrical work is more serious than the mechanical work.

Well there you go. There was really not much needed for it to fit the tunnel at least in my case. The electrical is not bad, especially if you use it as just an overdrive. I know swapping to a 5-speed (Tremec) from a 4-speed was lots more work.
 
Well there you go. There was really not much needed for it to fit the tunnel at least in my case. The electrical is not bad, especially if you use it as just an overdrive. I know swapping to a 5-speed (Tremec) from a 4-speed was lots more work.

Yup. That's what I needed. Thanks again, guys.
 
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