I wanna go faster

[BroncoOwner.me]

Got an all stock 66 170, c3, 4.11 with stock wheels and tire size. I understand our broncos are made for offroad and thats why they are geared this way but im looking for opinions for how to at least get a little more top end speed out of it. I have not decided what my long terms plans are for this bronco but i'm leaning towards a LUBR with a very minor lift (maybe 2.5) but I may not do that until sometime later next year. I'm looking for some basic advice like....

• If I went to this rear end gear ratio I could get a top speed of X
• If I went tire size X I could add another X to top speed
• how much the 170 and 3 speed limits my options

 

[Scoop]

G
[*]how much the 170 and 3 speed limits my options
[/LIST]

This^^^

You're just not going to get much more speed out the Bronco with the 170/3 speed. Upgrade to a 200 will help a little. But if you want to cruise all day at 70+ you'll need to swap in a V8. 302/5.0, 351/5.8, Mod motor or Coyote will get you where you want to be!

 

[SteveL]

If you want a faster highway speed you can lower the gearing to 350 or something but then you're gonna lose power

 

[sykanr0ng]

You're just not going to get much more speed out the Bronco with the 170/3 speed. Upgrade to a 200 will help a little. But if you want to cruise all day at 70+ you'll need to swap in a V8. 302/5.0, 351/5.8, Mod motor or Coyote will get you where you want to be!

/\/\/\ That pretty much says it all but he did leave out the 250 I6 as another option.

Bigger tires has the same effect as going to lower numbered gears.

 

[twiisted71]

***WARNING***Outside the box thinking

Since you have a bone stock rig, I STRONGLY suggest not lifting n going bigger.
Going with higher speed axle gears and beefing up your 170ci 6 cyl with a peppier cam is one route
200ci I6 swap with same recommendation
Mustang or T-bird Turbo 2.3L 4 cyl with 5 speed OD n TC from a Ranger and keep 4.11s Great mpgs, hiway speed, light weight offroad, quiet.
If you can make your engine stronger and higher revving you can swap in a NP435 or other granny geared trans/TC and still have good or better offroad grunt if you need to step up your axle gearing (lower numerically)
Personally I'd go with a 2-3L 4 or 5 cyl diesel and a Jeep 5 speed OD trans/TC from a 6 cyl (AX-15 or newer) ***AVOID the peugeot 5 speed used in the YJ Wrangler at all costs!***
You could have as close to as perfect of a vehicle as the factories could have offered!

A three speed is hard to work with and still offer modern speed expectations and low speed grunt without an engine with a w-i-d-e usable rpm band

Think '79 Ford F350 with a '97 Cummins and a ZF S5-47 and a NP205! The Holy Grail of looks, power, reliability, usefulness, and economical fun!

 

[jckkys]

My memory and contemporary road tests of '66 Broncos agree that a top speed of 70mph is about all your going to get. To maintain some semblance of a stock drive train, the 200 is an improvement, but not a big one. 4x4 utility vehicles were just that in '66. The CJ5, Scout, and Land Rover all had 4 cyl. engines at that time. I doubt you have a C3. These were Pinto transmissions that were to my knowledge not used in 4x4s. Original '66s are worth more as restorations. The '68-'76s don't have the collector appeal and aren't devalued as much by hot rod modifications.

 

[langester]

There are some gear ratio/ tire size calculators on the internet. You could check that out and play with tire size, that would get you higher top end.
Like others have said, that won't get you much with that size engine.
Good luck whatever you decide.

 

[bmbm]

faster

If you have 235 tires now going to a 31" tire will get you a little more top speed but just few more mph. the problem is the 3 speed trans with no od and the 411 axle ratio and 170 cubes. If you want to avoid the v8 conversion consider a 250 and 5 speed od trans like the M50d. Makes a big difference. But it might take some time to find a 250.
Check out fordsix.com

 

[pcf_mark]

My Dad (through a huge amount of machine work) installed a Thunderbird SC Eaton supercharger on his Heep 4.2 six banger. With 5 lbs of boost that turd scoots. I keep waiting for a Heep cast iron rod to fly out the side but it just keeps going.

 

[Whoaa]

NV3550 5-speed transmission, gives you a lower 1st gear and higher 5th gear O.D.

That said, the little 6 cylinder may not have enough poop to really use the O.D. And as a practical matter there is really not good reason to every drive a classic Bronco faster than about 65-70 mph.

 

[Steve83]

Yes, there are. If it's your ONLY vehicle, and you have to travel out-of-town occasionally for work or hobbies or family vacations, then you'd NEED to hang with traffic, which runs 65-80 in this city, and higher outside. You also NEED cruise control.

 

[sykanr0ng]

Yes, there are. If it's your ONLY vehicle, and you have to travel out-of-town occasionally for work or hobbies or family vacations, then you'd NEED to hang with traffic, which runs 65-80 in this city, and higher outside. You also NEED cruise control.

Totally agree with need to keep up with traffic, a lot of guys use their Bronco as their daily driver.

Been driving for nearly 40 years and never had cruise control, don't see any need to add it to my Bronco.

 

[bax]

I like the turbo and the 3550 overdrive option. Plus all of that can be used on the next engine. But I think ypu need the 200 ( or bigger ) engine to get to a standard bellhousing.

 

[pcf_mark]

Now this guy went a little far but you get the idea

https://www.youtube.com/watch?v=ThcKdqbIsd0

 

[BroncoOwner.me]

Lots of really great advice! Thanks! I hate to make too many mods since mine has such little rust and it's a 66. Not so much for the resale value but because I feel like it deserves to be kept as Ford intended her to be. Now I see why guys have more than one Bronco.

 

[Okbroncoman]

Hay, BroncoOwner.me

What is this search link?

http://reedweb.net/classicbroncos.search.html

Is it something you made up?
Looks a lot easier then the site search engine

 

[BroncoOwner.me]

Hay, BroncoOwner.me

What is this search link?

http://reedweb.net/classicbroncos.search.html

Is it something you made up?
Looks a lot easier then the site search engine

It's just using DuckDuckGo to search the site forums. I've found it very useful.

 

[blubuckaroo]

All factory broncos suffer from drivability limitation of only three gears. For example, gearing for top end reduces performance at the lower speeds, and vice-versa.
The fact that yours has the small motor makes that limitation even more painfully obvious.
The six cylinder models came with 4.11s and 4.56 as an option. If you went with the 4.56 along with an overdrive tranny like a NV3550, you would have improved drivability because of the increased gear selection.

Someone else may have experience with this to tell you if that tranny swap is even possible.

Keep us posted. Research on a swap like that would be valuable to anyone with a Bronco like yours.

By the way, I love the sound of a six cyl Bronco. Don't ruin it by changing that. If you want a V8 Bronco, buy one that's that way already.

 

[bmbm]

faster

If you want to maintain original appearance of your Bronco then staying with a six is perhaps best. The 200 is virtually identical to the 170 and the 250 is pretty much indistinguishable from the 170/200. It is almost 2' taller. The 250 is a fairly straight forward swap with a little work to the oil pan and clutch/throttle linkage. If you are looking for the lowest cost step try the 31" tires. Depending on wheel back spacing and ability to modify the inner fender sheet metal it might give you some of what you need.
Of course all this depends on your budget, mechanical skills and intended use.
I remember that when I had the 200 it always felt like it could have used an od gear on level roads. The other advantage to a five speed is you get 1-4 gears with a decent ratio spread which is very usable especially with a smaller motor. I remember on long grades shifting from 3rd to 2nd and it seemed like I could have used a gear in between.
The 80-83 block can be modified to bolt up to a sbf bell so you can use an M50 trans.
Having said all that I can tell you that for me a 250 with the NV3550 and 411 gears is a good driving experience. Good acceleration and comfortable highway cruising at 65-70. It is a competent daily driver.
I hope this helps.