4 speed OD unit....

thrashingcows

thrashingcows

Drowning deep in my sea of loathing...so I'm
Passon Performance 4 speed OD unit...Anyone run one of these units or know someone who has one?

Just thinking into the future for the wagon...going to install a manual tranny but want a OD set-up. I've been considering doing a stock A833 and then a Gear Vendors OD tailshaft on that for a 8 speed tranny but the Passon 4spd OD unit looks interesting too.

Thoughts and opinions?
 
http://www.passonperformance.com/

These guys are basicly repro'ing all the parts for the A833 and they offer either as a gear set for your original case or a complete tranny, also the OD set-up is stronger than the late 70's aluminum OD units. Also the spread pattern between the gears is more ideal with a final OD ratio in forth of 0.79.6-ish.

What I like about this set-up is there is no modifcation to the car...other than the stock four speed conversion, since it's a stock A833 tranny all the parts can be re-used, were as the Keisler requires some tranny tunnel cutting and mods and schtuff.

I really like the TKO tremec stuff but I'm leary about cutting up the tranny tunnel in the wagon...not sure why? I have a spare tranny tunnel and could put everything back to origianl if I ever wanted to.

The Passon performance gear set is about $1700 and the complete tranny is about $2800...but this is a brand new 833 tranny no used parts. Keisler set-up would probably run $3200-$3500 or more.

I have been doing lots of research on-line and reading lots over on that other board...:shifty:[smilie=f:We may not speak it's name here....:naughty:

Still undecided...:huh:
 
Not familiar with it either, but if you were to get an OD trans from an '80s slant-six/318 2WD pickup, it'd be the right length for the C-body application. I'm not a huge fan of the add-on aftermarket overdrives, since they mount to the tail end of the transmission. That could theoretically mess up driveline angles, as well as putting a stress on the rear mount for which it was never designed, as well as a cantilever effect on the front mounts. Those are notoriously weak in the first place, as engine torque has a tendency to rip the LH mount in half already... now you're lifting on it, too? I could be 100% wrong, but those are my questions.
 
You responded whilst I was posting. :doh:

To my knowledge, the Keisler TKO units require no cutting whatsoever... Friend Kevin has one in his '71 Charger R/T and it was a bolt-in, using their kit.

However, and you didn't hear this from me, someone is working on a transmission that will require no kit, merely a shifter change (for the extra gear) to put a 5-speed in direct replacement for the A833. Hang tight, folks... the development's well on its way, and is supposedly a higher-capacity gearbox than any Tremec.
 
Jass...good points too...I hadn't thought of the drive shaft angle and the cantilever effect as well.

The Passon units are a new A833 units with a lot more strength than the 70/80's aluminum units. They are claimed to be even stronger than the Hemi 18 spline units due to the material being used to manifacture them. Also the gear spread is better on the Passon units than the aluminum OD units.

But I could get an aluminum OD unit for a lot cheaper than the Passon unit.
 
Dohhh...posting while replying...:doh:

Jass that is good news...I'm in no hurry just trying to make a decision...but I can wait...:toot:
 
Dr.Jass said:
To my knowledge, the Keisler TKO units require no cutting whatsoever... Friend Kevin has one in his '71 Charger R/T and it was a bolt-in, using their kit.
Click to expand...

I believe the tranny tunnel mods are mostly for the 68-70 A & B body cars...and C-bodies...the later 70-74 E-body and 71-74 B body cars have the same basic floors and I believe only need a small notching of the shifter opening to clear the tremec shifter mechanism.
 
So here's one of the reasons I'm having trouble deciding...OD gear ratio

TKO tremec you can get the final ratio in .64, .68, .82 depending on what kit you want.

The Passon performance unit final ratio is .80

The stock aluminum case 833's final ratio is either .73 or .78 depending on what unit you get.

So now I have to figure out what gear ratio I am going to run in the car....which then alters what final ratio I would need...this is a viscous cycle and I've been using this speed anyliser to run through possibilities....

http://vexer.com/68rt/speed.html

Pretty cool and you can do lots of figuring from stock to modified.

So what's a good cruising RPM for a 440 at 70 MPH...I figure about 2200rpm?
 
Here's the trick: what Passon claims to be a "better gear spacing" is dependent on your engine combo. If you're running a stock or mildly-modified 440, as opposed to a high-winding, peaky W2-equipped 340, then wider gear spacing ain't so bad. Stock(ish) 440s have a torque plateau, rather than a peak. Dropping a gear with a stock OD trans is a big drop (particularly 1st to 2nd), but if the motor's making a ton of torque, it's gonna pull regardless... and that big 1-2 drop isn't necessarily a problem, either.

I spent a lot of time, back when it looked like I might drive again before the Mayans predict the world will end, figuring out my ideal daily driver (you don't want to know). One of the things I spent a lot of time calculating was optimal gearing based on factory parts, from a fuel mileage and acceleration standpoint. I came up with a stock OD trans, 3.09 first gear, 1.78 second, 1.00 (direct) "third", and the .73 fourth, combined with a 3.3 gear. I was lucky enough to score a set of 741-case 3.36 gears, which nobody offers, and was only used by the factory for two years. Literally, I get the launch of a 4.10 with the highway economy of a 2.45. My plan called for a broad torque curve that would not be adversely affected by RPM drop between gears, much like a 440.

Using a 3.23 gear, you're either gonna get a launch like a 4.0 gear or a 3.73, depending on which close-ratio you'd like to use for comparison (2.47 first, or the earlier 2.66), with a final-drive equivalent to a 2.35 rear cog.

As far as strength, you ain't got what it's gonna take to break a factory aluminum case A833OD. Sorry. I know of one that's spent many happy years--over 20--behind a Hemi. If you don't believe me, look at the case dimensions of the Borg Warner Super T10, or the Muncie M21/M22, both of which have lesser outer dimensions and case thicknesses than the A833OD, then remember that LS6 (454/450HP, so they claimed) 4-speed cars were virtually all M22s.

The weakness of the A833OD is greatly exaggerated, primarly by those who'd like to sell you parts. Imagine that.
 
Damn good info Jass...Thanks. :2thumbs:

I wondered about the torque of the 440 with the gear split on the factory OD units...guess I'll probably go with one of those since I'm not into high HP's and racing, just looking for a good cruiser. Will probably run either my 3.23's or a 3.55's.

Thanks for the help Doc....:cool:
 
Hey Thrash, we just installed a 4 spd OD into our '68 Valiant, 225....completed the whole engine/tranny installation about 2 wks. ago. Problem is, we got the tranny with the car when we bought it in '99, and have no idea what it is actually out of. We are just guessing that it came out of something from the late 70s, early 80s, maybe an Aspen or Volare? Anyway, Mike didn't want to cut a hole in the floor, so he made it work on the column shift. Forward gears are there, reverse is on a cable under the dash (put the shifter into neutral, pull on the Hurst T-handle under the dash). I just finished driving the car to and from Moparfest, works great, no problems. Can't help you with any of the technical questions, that's hubby's department, but it was a very successful application, and it sure garnered a LOT of attention in New Hamburg! On Saturday morning after we got there, it took us 2 1/2 hrs. just to be able to get away from the car to go and get our registration! Mike loved it......was in his glory!
Anyway, if you have any questions, or want pics, let me know. I can handle the pics part, and can ask Mike any questions. (He's somewhat computer challenged....)
 
I've been debating on the passon gearset also. I have 4.10's right now and am leaning towards putting 3.55's in and leaving it at that. Applying Jass's theory with my engine, I think the od unit from passon or a original od unit might be the way to go instead. The engine on the dyno did produce at least 365 lbs/ft from 3200 to 5200 rpm. I would think that would handle the gear spread. Of course, the ring and pinion would be much cheaper.
 
Hey Jass.....How are they getting around the bellhousing problem with running the 833OD??

I have heard you can't mill out the stock aluminum or cast units to accept the different bearing retainer size? The 833OD unit has a bigger bearing retainer cover..right?:huh:
 
Yes, it does... but the new trans is not designed around an OD unit. They actually took one of my close-ratio long-tail transmissions as a sample from which to design. Argh.

Regardless, an earlier 4.80" front-bearing retainer bolts right on to an 833OD with no issues. I've done it myself. If you can't score a used one from a used trans (and the 3-speed units are identical, if you're searching), they're still available new from Ma.

I don't know, but I think the retainer size was increased to make sure the right trans ended up in the car for which it was intended. I can see no other reason for it, as the smaller unit fits and seals perfectly.
 
Passon has a widespread good rep as far as 4 speed parts and rebuilds are concerned. Never heard any talk regarding the OD units tho...
 
Passon has a great rep & gave me a lot of advice over the phone, but I don't want a 3 spd w/ overdrive. I've heard horror stories about the Keisler swap, but good things about the Gear Vendor's overdrive unit. That might be a solution.
 
Dr.Jass said:
Yes, it does... but the new trans is not designed around an OD unit. They actually took one of my close-ratio long-tail transmissions as a sample from which to design. Argh.

Regardless, an earlier 4.80" front-bearing retainer bolts right on to an 833OD with no issues. I've done it myself. If you can't score a used one from a used trans (and the 3-speed units are identical, if you're searching), they're still available new from Ma.

I don't know, but I think the retainer size was increased to make sure the right trans ended up in the car for which it was intended. I can see no other reason for it, as the smaller unit fits and seals perfectly.
Click to expand...

Doc you are a wealth of information....an asset to this site and to anyone who has benifitted from your knowledge and insight....:2thumbs::giggedy:
 
Damned shame I'm an asshole, isn't it? :D

Thanks for the kind word, TC.

Passon is very good at what he does, there's no doubt... and I'm sure that improvements in metallurgy have made for stronger gears, synchros, and everything else over the years, but from what I've been told over the years the aluminum transmission's weak point was the case... and yet, I've seen guys push ridiculous horsepower through 'em, using stock close-ratio gearsets in place of the OD setup, which has big, beefy gears in the first place.
 
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