New member... questions about towing with slant six, transmission swaps

[zackw]

Hi everyone, thanks for letting me in! I'm not sure what was up with the account registration, I didn't get approved for a while. But I'm really glad to be able to post.

I bought my D100 last year and I'm wrestling a bit about what direction to take it in. It's a farm truck, super original, 70k miles with maintenance paperwork dating back to the 70s.

I want to keep it that way, but I don't have a lot of space, and if I'm going to have a truck I'd like to be able to tow at least 6000#, i.e. another vehicle on a trailer.

Currently it has a slant six with an A745 (3 on the tree), 3.5 rear end. I wanted to swap in an NP435 so I can use the granny low to get going with heavy loads. If I did that I would like an Advance Adapters gear splitter for highway driving... But I can't find an NP435, only A833OD trannies. I would actually like that a lot for cruising, but it has the same first gear ratio as the 3 speed (3.09), which already has trouble pulling 2000#. If I went to a 4.10 rear end, could I tow 6k with the A833? I know brakes etc are a must. I've done a few engine upgrades like Dutra duals, two barrel carb...

I really like the slant and I'm a member over at the slantsix.org website. But lately I gave some thought to a 318 swap. I have a great running 318 in a '68 Fury that I could use... What all do you think about all this? If anyone has a 4x2 NP435 with a slant six bell in Texas... I will take it off your hands

[Txas2step]

. Very nice '69 you have there.I have a np435 that I bought yrs ago that has the later model 23 spline count ( seller said it was out of a mid- 70's dodge truck ). It is in excellent condition. I'm in Houston. PM me if you want to take a look at it.Just collecting dust in my storage unit.

[zackw]

Thanks! And that's music to my ears. A few hours on this site and I'm better off than some weeks of scouring CL... I'm in Houston right now, although my truck is in Waco. Hopefully I can come by and check it out soon. I'll PM you sometime.

[712edf]

I have a 23 spline NP435 in Wichita Falls, Texas, which is a few hundred miles away. I don't have the bell though.

Bucky

[Txas2step]

I have a 23 spline NP435 in Wichita Falls, Texas, which is a few hundred miles away. I don't have the bell though.

Bucky

The bell from the 1969 A745 should work ,Bucky. ( and the clutch assembly? Help!)

[712edf]

As far as I know the flywheel/disc/PP would work. The bell depends on if he switches to the 318.

Bucky

[Txas2step]

The hydro bells are the same /6-318...the mechanical bells are different /6-318?

[zackw]

If I recall correctly, the later 23 spline shaft was for an optional mechanical clutch? It seemed odd to me that the earlier spline count was for a hydro clutch/bell, but I remember reading that somewhere. This would actually work better for me because the existing clutch is mechanical. But I would need a clutch disc and pressure plate because I think factory parts are 10-spline. Not sure about the flywheel.

Does the A745 really have the same bolt pattern?

[Txas2step]

In 1969 the Sweptline series changed from the 10 spline trans w/hydro clutch to the mechanical w/23 spline trans and clutch.

[zackw]

Good to know, the clutch kits available on RockAuto all show 23 spline, so I guess that includes the 3 speed transmissions as well.

[712edf]

If I recall correctly, the later 23 spline shaft was for an optional mechanical clutch? It seemed odd to me that the earlier spline count was for a hydro clutch/bell, but I remember reading that somewhere. This would actually work better for me because the existing clutch is mechanical. But I would need a clutch disc and pressure plate because I think factory parts are 10-spline. Not sure about the flywheel.

Does the A745 really have the same bolt pattern?

What factory parts are 10-spline?? If you have a 69 with a mechanical clutch then I think you already have 23-spline set-up, unless 3-speeds are totally different than 4 speeds.

Bucky

[zackw]

I think you already have 23-spline set-up, unless 3-speeds are totally different than 4 speeds.

That was my concern, now that I think about it, doesn't make much sense.

[Hobcobble]

I think you already have 23-spline set-up, unless 3-speeds are totally different than 4 speeds.

That was my concern, now that I think about it, doesn't make much sense.

www.hrclutch.com

This outfit will get you what you need the first time and
they'll give you good parts.
John

[hmaynord]

[/quote]


www.hrclutch.com

This outfit will get you what you need the first time and
they'll give you good parts.
John
[/quote]

they did me right too

[zackw]

Thanks John, I sent them an email ..

I suppose I should clarify one of the big questions, namely, if I chose an A833OD over the NP435, could I expect to tow anything substantial by using a low-geared rear end? I was thinking 4.10s. This would give me an "effective" final ratio of (.71)(4.1)=2.87 in overdrive, which could be nice for the freeway. But I'm not sure that 4.10s are enough of a difference versus the existing 3.5s that it will increase my towing capacity. First gear in the A745 = first gear in the A833OD so that's not a factor. Anyone run 4.56 gears? That would give a final ratio of 3.23ish with overdrive, liveable, and maybe first would be low enough to tow.

I definitely want overdrive, in picking the NP435 I was hoping to get the gear splitter from Advance Adapters, but I've yet to call and see if they'll make one with the Dodge bolt pattern and input shaft.

[PwrWgnDrvr]

Ive towed all over the country in swepts with 318's and both 4.10 and 4.88 ratios. There were plenty of times and places when the 318 was too gutless for the task. I would NEVER consider doing it with a /6.

[712edf]

I guess we need to know what you are towing (just a car hauler or enclosed trailers too), where & how often.

Bucky

[zackw]

Ive towed all over the country in swepts with 318's and both 4.10 and 4.88 ratios. There were plenty of times and places when the 318 was too gutless for the task. I would NEVER consider doing it with a /6.

But what transmission was that with? I don't need to be going anywhere fast, just want the truck to be able to do truck work when called for.

I guess we need to know what you are towing (just a car hauler or enclosed trailers too), where & how often.

I think just a car hauler with a car up to 4000#. To be safe, probably 6000# total, although I'd like to get a lightweight trailer that's more like 1200#. Not very often, but I do buy/sell/trade vehicles frequently enough that Uhaul are making more from me than I like! Maybe twice a year up to 400 miles.

[PwrWgnDrvr]

NP 435, wide spaced. Its not the "get going" that's the problem, its 4th gear (direct, not OD) over the highway, up a grade of any length or slope.

[zackw]

I know getting going wouldn't be an issue with the granny first gear. I know final gear will be slow, no plans to use OD when towing for sure, but thankfully I'm in Texas so it's very flat at least where I am now.