Using a van 4-speed to create a cheap OD trans.

[bull]

Just got done talking to my old Mopar buddy and he said he knows of a guy who's started rebuilding mid-70s Mopar van 4-speeds with an overdrive gear attached to third gear for use in cars like ours instead of spending $3k on a Gear Vendor unit or similar. I don't have all the details yet but thought I'd ask around here to see if anyone has any experience with this type of thing.

He said the downside of this idea is that the van trannies are not exactly heavy-duty so putting them behind a real power house might not be a good idea. Also you've got OD attached to third gear (that's apparently the only one that has room for it) so your shifting pattern will be different than stock. Basically 4th becomes 3rd and vise-versa.

[hemihead]

Why not just use the A833 from a Volare or Aspen ? It has an OD 4th . 

[694spdRT]

The trans you are talking about is an overdrive 833. I am going to use one in my Challenger. They are 23 spline and came behind 318's and slant sixes in vans and light duty 1/2 ton 2wd trucks. They were also used in A bodies like the Volare/Aspen but the tailshaft is shorter on those and doesn't work to well in our applications without some mods. The shift pattern remains the same because the 3-4 shift lever is flipped down on the tranny. 3rd gear in the tranny has the overdrive gearset like you mentioned and becomes OD. Direct drive(old 4th) now becomes 3rd gear once the levers are swapped. The wider gear spacing is not optimal for performance and 1st gear is lower than a standard 833. It is a much cheaper alternative when you want OD.  Most of the tranny cases are also aluminum instead of cast iron. Also, the front bearing retainer is larger so it will not fit into most bellhousings without having the retainer turned down or the bellhousing hole enlarged. If you have a small block(or slant six) you can use the factory bellhousing from the overdrive vehicle.

Chryco has used them in his race cars and if they are good enough for him that is good enough for me.

[694spdRT]

Here is a picture of the van tranny I am using in the Challenger and one of the 18 spline in the Charger. You can see it has the same long tailshaft but 2 shifter mounting pads. The rear pad is used for E bodies and 3rd gens.

[bull]

Yea, that's it. Thanks. Have you been able to try one of them out yet? If so what do you think?

[694spdRT]

No I don't have the Challenger done yet. I remember dad driving a pickup in the late 80's with one though. The biggest complaint I have read about is the gear spacing but I have no opinion on that yet.

I plan to use either the original 318 or 360 Magnum from a truck with this tranny. My plan is to run a 3.23 or 3.55 rear and 14" Magnums with 26" tires.  Final overdrive gearing in the 2.40 to 2.60 range should be good for economy with a low rpm cam. 

[bull]

That sounds like a good combo. I'd be tempted to go with the 3.55 myself or even a 3.91 but the 3.23 would be great on the highway. Probably do 150 mph no problem. Have you heard if you can use the original driveline with the van and truck trannies?

[694spdRT]

As far as I know if you already have a 4 speed car the tranny is a bolt in deal with the exception of the bearing retainer size and changing the shifter location and rods.(the shifter mount for the trucks sits up and forward) I need to use the rear mounting pad for the Challenger but the Hurst shifter mechanism from the van looks like it should work with the proper rods. I will take a look at the tranny mount a overall length tommorow to make sure it is a "bolt in" deal.

I think the 3.55 gears would probably work the best too because the low 1st gear will launch like a 4.10 which might help with our heavy cars. That is also why I thought I could get away with 3.23's because 1st would almost be like 3.91's with a standard 833. Anything lower than 3.55 might seem like a "granny" 1st gear on the street unless you have tall tires.

[Rolling_Thunder]

I am running one of these in my boss's Superbird and one in his 68 GTX...        here is the deal

1) if car is originally a 4-speed car it will bolt on except for the bearing retainer is too large, either machine the retainer or bore the hole in the bellhousing larger
2) 3rd gear is the OD gear, however the inverted shift lever keeps a normal shift pattern
3) These transmissions will put you just around 2000rpm @ 65mph with a 26" tall tire and 3.55 gears


WARNINGS:
1) These units are "wide ratio" transmissions with a 3.07 1st gear, keep this in mind if you are running a low torque engine (318 and 340) as the performance WILL suffer greatly
2) These units use aluminum cases which have been known to crack and break with lots of torque put to them - in reality, they are a nice street transmission and assuming you are running street tires and a mild engine build you will be safe.
3) The shift linkage is different than the typical 4-speed linkage (3/4 lever is different)

[RallyeMike]

Bull,

My buddy runs one in his 340 cuda with 3.91's. Lots of snap for the street and good freeway cruising with this set up.

I'm running one in my 72 Charger race car behind a 383 with 3.23's. I also have one in my /6 Demon with 3.91's.

As stated, the ratios are widely spaced. Everything will fit as a stock bolt in other than possible modifications to fit a bellhousing. /6 housing are out there plenty, and sometimes you can run past a small block housing. They did not put this trans behind a big block, so you have to make the aformentioned mods to mate to a bid block. Lakewood also makes a scattershield for this application.

The aluminum cases are nice and light, but the countershaft rides right on the aluminum case. This can be a failure point if you are drag racing or have a ton of HP that is regularly applied.  Mine has seen some rough duty and is ok so far, but it is not subjected to the kind of shifting that drag racing subjects one to.  I have a spare one in the shop that I am going to rebuild with a bushing placed in the case at the countershaft on the advise of those who have used these trans for similar race duty. They have found that under constant heavy loading, the case eggs out where the countershaft rides. It would be fine on a mildly built street car.

This is a great  modification!  I have picked up these trans up at swaps for $100-$150.

[squeakfinder]

So aside from the the bearing retainer, these aluminum case's will bolt up to a small or big block bell housing?

[RallyeMike]

Yup. The 833 OD's are the same basic case casting as the 833. 

[694spdRT]

How far can the front bearing retainer safetly be turned down? The big block bells are fine but didn't some of the small blocks have pretty small diameter holes.

[bull]

What kind of casting numbers should I look for on these target trannies, in case I find one that's already been removed?

[694spdRT]

The part number stamped in the aluminum housing on mine is PP833 2 899.

There is another number cast onto the driver side that is C-13546 B.

The tailshaft is approximately 17" long and the bearing diameter has to be over 5" to be the right one.

Hope this helps.

[Mick70RR]

There's a lot of info about overdrive 4 speeds here.

http://www.slantsix.org/articles/4-speeds/ODA833fourspeed1.htm

[firefighter3931]

Bull, why not look ar a Passon 4 speed overdrive.  It fits in the stock tranny case and is made to be abused. 

I wouldn't be using an aluminum case OD trans in anything i planned on having any fun with 


http://www.passonperformance.com/


Ron

[bull]

I'll check it out. Thanks.

[Chryco Psycho]

I use the van / truck trannys all the time , they basically bolt up to the belhousings small blk or big blk , except for the front brg retainer

[Rolling_Thunder]

Well - i'll say that I built a Passon OD unit for Car Craft Magazine last year and I really question it...      seems like a 18 spine gear set - nothing else seemed very impressive...      My boss's superbird still has the aluminum OD unit in it - I took it out with slicks a couple weeks ago and it is still running around like a champ...       I would bush the aluminum case if i tore it apart or i would swap guts to an iron case

[RallyeMike]

Question what? Aint nobody making 30-year old 18 spline trannies no more, and definitely not OD 18 splines ! I think they have filled a void in the market for
those who want stock appearance, a reasonably stout trans, and some OD for the highway.

I don't follow the prices much, but I think the cost of the Passon parts kit is in the range of a used 30-year old 18-spline. Not a bad deal.
For cost of the fully built trans though, it seems a better buy to step up to a real 5-speed instead of Passons 3+OD set up.

I have to say still, for 90% of users the OD 833's are just fine and one hell of a bargain 



 

[tecmopar]

As some guys on here know, rebuilding Mopar 4-speeds was my specialty for over 35 years when I stopped about 2-3 yrs. ago. I have been doing this conversion for myself and customers since '77 and for a street car its a pretty neat set up. It is a very wide ratio but still quite driveable and with such a low first gear the car leaves like a scalded cat. Its also actually very easy to do as there are a few different ways to meet your needs. The simplest way is to swap out the internals from the OD box into yours but there are a few things to look out for so if anyone needs specific info just PM me with what you have and what you want to do and I'll guide you through it, good luck.

[bull]

Bull, why not look ar a Passon 4 speed overdrive.  It fits in the stock tranny case and is made to be abused. 

I wouldn't be using an aluminum case OD trans in anything i planned on having any fun with 


http://www.passonperformance.com/


Ron

I emailed Passon about it, Ron, and their OD kit is only for the 18-spline trans.

[firefighter3931]

Bull, why not look ar a Passon 4 speed overdrive.  It fits in the stock tranny case and is made to be abused. 

I wouldn't be using an aluminum case OD trans in anything i planned on having any fun with 


http://www.passonperformance.com/


Ron

I emailed Passon about it, Ron, and their OD kit is only for the 18-spline trans.

Dang....that's too bad !  Those Passon 4spd overdrives are bulletproof....it would have been a nice option for you Curtis 



Ron

[bull]

Bull, why not look ar a Passon 4 speed overdrive.  It fits in the stock tranny case and is made to be abused. 

I wouldn't be using an aluminum case OD trans in anything i planned on having any fun with 


http://www.passonperformance.com/


Ron

I emailed Passon about it, Ron, and their OD kit is only for the 18-spline trans.

Dang....that's too bad !  Those Passon 4spd overdrives are bulletproof....it would have been a nice option for you Curtis 



Ron

I actually got some clarification from them today. It can work but not as easily as it would with an 18-spline trans. but the price is still about half that of a Gear Vendor unit:

"Curtis,

You can convert your 23 spline into this unit.  It would become a hemi 4 speed (18 spline input shaft) when done.  Since it is an entire gearset, you can make your 23 spline into this 18 spline unit.  The 23 and 18 spline units are identical inside except for the gearset.  These conversion kits are $1695.00.  You would need to change the bearing retainer as well because your 23 spline retainer will not for over the 18 spline input shaft.  These retainers run anywhere from $85.00 - $125.00 depending on the configuration

Thanks,

Jamie"