Replace 3 Speed Toploader in a 1966 170ci - can I change to 4 speed?

[DrDanWWW]

I have an HEF DA 3 spd in my Aug 65 build. The 2nd gear needs some effort and grinds a bit. Plus, I sure would like to find another gear near the top. In other words, driving floored at 55-60mph is a drag.

Questions:
1.
If I just stick with the HEF DA 3 spd, and I want to buy one, do I have to stick with an exact match, an HEF DA? Or can I install another HEF tag, or even a V8 RAT, RAN? What is objections and hurdles?

2.
If I want to jump up to a four speed, a) is it even possible? b) does it get me 65-70mph on the highway, so I don't feel like I'm going to be run over? ( Don't want to go much faster than 70 - gets dicey. And I have all new suspension, PS, 4W disc PBs, and 31" tires.)

I've looked for a thread on the 3 spd 170/200 inlines and didn't see anything. The Transmission Tech Article assumes a V8. Maybe y'all can show me the threads. And I keep reading the Ford Falcon Handbook, and I have to say it sounds like you can swap in a different tranny, but it gets cryptic real fast about just how much trouble the swap causes. The Handbook assumes you want performance (hopped up), and never mentions a Dana 20, etc.

Any experience and info is appreciated.

 

[hankjr]

Howdy. Regarding your point 2. it is my understanding that the top gear on 3 and 4 speed are the same. 4 speed gives one more gear between first and last.

there is a tech guide here with gear ratios

https://classicbroncos.com/tech/category/transmission/manual

Hank

 

[DrDanWWW]

Right, thanks. yep I forgot the ratios end up the same. I need a bigger engine if I want to go faster. I'm looking for a 200 to rebuild (have rebuilt). I like the inline 6. So my other question is the more pressing question: when looking for a replacement 3 speed toploader, do I have to stay with an exact match HEF DA?

 

[Broncobowsher]

I forget all the 3-speed codes, but it has to be an I6 transmission. the v8 transmission is longer and won't fit.

 

[DirtDonk]

there was a 4-speed overdrive that a few are using, but that does not necessarily get you faster either if the engine lacks the poop to do it.

but what is your tire size and gear ratio combination currently? Maybe it only sounds like you're over-revving it?
then again, many six'ers came with 4.56 gears, and if you're still running 27 or 28 inch tall tires, then that is almost 3700 rpm at 65mph. So while not exactly "over-revving" the engine, it's not in it's happy place either.

Paul

 

[DrDanWWW]

I am running 31s" and my gears are 4.10, 9"rear. I don't have a tach so I don't know the rpms. So I don't know if the engine's happy, but my foot isn't happy

Here's where I am getting my toploader tags info:
http://www.davidkeetoploaders.com/3speedidchart.htm

(sample cut n pasted)
HEF CT 1965-66 Fairlane, Falcon 200, 289
HEF CU 1965 Falcon 289
HEF CV 1965-66 Mustang 289
HEF CW 1966 Mustang 289
HEF CX 1966 Fairlane, Falcon 200, 289
HEF DA 1966 Bronco 170
HEF DB 1966 Bronco 289

This info makes me wonder if it is possible to run one of these HEFs matched to a V8 in a I6. Look at HEF CX -??? I get it - the RAT/RANs are longer. For shopping around purposes, I just wonder if any HEF will fit.

That (Dagenham?) 3 spd with the overdrive is rare, fragile, and expensive according to the Falcon Handbook. I haven't seen any on FB or eBay or from a vendor.

I do appreciate the help. Thx. I just want to make sure I buy the right toploader installed. I know some of you will say I should just rebuild my current one (then it fits!), but I have never rebuilt a tranny and every time I mention it to mechanics they start talking about spring loaded ball-bearings. So I feel better just spending the money on one from Graveyard ($575) rather than goofing up my only transmission. - I think.

 

[bmbm]

od trans

The last couple years of 200 production was called the big bell 200 and by drilling two additional holes in it you could bolt up a v8 bell. Then you could get one of the 3spd plus od trans from I think mid 90's 150. The large bell 200 is covered in the Handbook. Other than that my research from about 12 years ago led me to the 250 which has the v8 bell capability but is best with oil pan mods and pickup tube. Or if want to do a lot of work you can get a 300 in there a few have done it.

 

[DirtDonk]

I am running 31s" and my gears are 4.10, 9"rear. I don't have a tach so I don't know the rpms.

Don't need a tach as long as your speedometer has been corrected for the larger tires and you know it's pretty accurate.
With 4.11 gears and a tire with a rolling diameter around 30" or so (that would normally be a fairly large 31, my BFG's are just shy of 30) your engine is turning over at about 3,000rpm at 65mph. Short of the clutch slipping or a different measurement of the tire, this rpm is pretty much etched in stone.
And not a horrible place to be with your engine. No idea what it's maximum rpm is, but at highway speeds you're pushing a ton of wind with that flat front end (aerodynamics of a shoe box or superman's old telephone booth) so you need your engine to be revving up due to it's lack of overall horsepower.
I'd say you're in a pretty good spot.

If you could stay at around 55mph though, you're pushing a lot less air and your engine would be spinning at just a tick over 2500rpm. Not a bad place to be as long as you have the patience.

So I don't know if the engine's happy, but my foot isn't happy

It's probably just fine as long as it's in good condition and well tuned up.

PAUL