stock 3 speed vs. c4

[rockinrich]

Paul's advise is solid. But I will add just a little. If you really are planning a NV3550 or other overdrive transmission that will play into the gearing as well. Paul's 4.56 with overdrive combo will net an effective ratio of about 3.23 which makes for a nice highway gear. But the actual 4.56 ratio is fun on the street and trail. (effective ratio is actual ratio x OD ratio)

I ran a 33" and 4.10 combo without overdrive for a few years. Was fun to drive. I could still run interstate speeds. These old school V8s are happy running that speed. The cooling fan just makes a lot of noise.
Later I went to the same overdrive that Paul is using and went to 4.88 gears. That was also a blast to drive, highway was better as the effective ratio was 3.42

Thank you very much,i appreciate your help,what about the ax 15 tranny,what gearing would you use for that? Thanks again!

 

[rockinrich]

This is where it's best to make a plan, for your build, and stick to it. Otherwise you can end up with an evolution of changes.
Back when I had a C4, I planned no bigger than 33" tires, because that's the limit for my 28 spline axles, and 2.5" lift.
The car was already poopy with 3.50 gears and 32" tires.
I knew that 4.11s would be fun, on the street, but a bit low for the highway.
I was considering something in between. There is gear options 3.70/3.73 or 3.89/3.92 for the Ford 9"/Dana 44.
If you plan to keep a three speed or C4, I would recommend either one of those combinations over a 4.11 gear set.

Thank you very much for the help,what if i went with an ax 15 what gearing would you recommend?Thanks for the help!

 

[DirtDonk]

...right now i just have a 3 speed with about 88,000 original miles from what the older gentleman owner told me but it runs strong so could be true, anyways is the original 3 speed just junk?

No, not at all. In fact it's one of the nicest transmissions ever made.
It's smooth shifting, quiet, very reliable when not abused or used in too heavy of a working vehicle, inexpensive and simple to work on.
It's main weakness as far as I'm concerned, and as far as 3-speed trannies go, was the piss-poor choice of gear ratios for a truck. Even the close-ratio version, which had a great 1-2 shift range, sucked for a Bronco (would have been sweet in a lightweight car) big time because then the first gear, which was already too high, was just WAYYYY too high for a heavy rig and off-roading.
Yes, even in low range!

I mean it is factory tranny,do people just want more out of a tranny,is that why they switch?

Exactly. It's a 3-speed, and has lousy gear ratios for many users. Not everyone of course, and there are still a lot of Broncos running around with their original gearboxes in them. Driver's still smiling too.
But many of us that went off-roading in our Broncos wanted at the very least, an under-drive first gear. AKA granny low.
And those that spend much time on the street with the optional 4.11's and 4.56 gearing in the diffs were always hunting for another gear on top of third. Funny how often you actually try to shift into one too, after converting from a column shift to a floor-shift setup. Drive even one 5-speed with overdrive in your life and you end up always wanting that extra gear in whatever else you drive.
It's all about convenience and efficiency and just having more choices.

Also if you were to replace it and mostly on road but want it capable off road would you go with an ax15 or nv3550?

Either one, but that little bit of extra low gearing in first gear of the 3550 does give it a slight advantage off road. Depending on what type of off-roading you do that is. The AX probably has a better overall gear spread for shifting and keeping the rpm in a good range each time, but that few extra points that the 3550 has in first might just give you an advantage.

I drove mine a lot. And for all those years of lusting after an NP435, NV4500, or anything with even remotely better gear ratios, there were many circumstances where there was just never the right gear with just 3 to choose from. First was too low for good street manners, but too high for off-roading. Second was never where you wanted it and the jump between it and third was a deep one and if you were loaded up for a weekend's worth of camping and did not have the engine revved to the moon, it would just bog down in third, then over-rev again when you had to shift back into second.

More and closer spaced gears is almost always better. Not always 100% necessary, but still "better" for most conditions.
Which is why you now not only have 5-speed manual transmissions and 4-speed autos, but why 6, 7, 8 and even 10 speed transmissions are the norm in almost every lineup of vehicles. The new Bronco even has what? A 7-speed manual transmission?
Hmm, I wonder how one of those would swap in!

I heard jim at wild horses say on a video they are basically the same tranny,are there any differences?

Sure, but I could not quote you each and every one. Basically the reason they're considered the "same" as each other is that they are almost identical in physical size, have the same number of gears, with almost the same ratios, and probably have similar reliability records.
I can't tell you one is better than the other because I have not spent any substantial amount of time with either one.

Paul

 

[DirtDonk]

Thank you very much for the help,what if i went with an ax 15 what gearing would you recommend?Thanks for the help!

Fill in all the blanks and I'm sure you'll get a better, more informed answer.

1. How will it be used? Exactly?
2. What tire size will you ultimately go with?
3. What engine will you ultimately have?
4. What other equipment will be added? In other words, will it be a much heavier Bronco than it is now, or will it remain close to stock weight?
5. And finally, along the lines of question 1, if you need to compromise between street, performances street, trail, or performance off-roading, which way would you go?

Paul

 

[blubuckaroo]

Thank you very much for the help,what if i went with an ax 15 what gearing would you recommend?Thanks for the help!

That's speculative. Depends on your use.

An NV3550 has 4.01, 2.32, 1.40, 1.00, 0.72 ratios. I like my 4.11s because of the NV3550's low 1st and moderate overdrive. I have a pretty fast piece of interstate I commonly travel. The 4.01 1st gear would be almost useless with anything lower than 4.11s and 33" tires.

An AX15 has 3.83, 2.33, 1.44, 1.00, 0.79 ratios. I think a 4.30 or 4.56 would work pretty well with your 33" tires. I think the ratios on this tranny are too high for 4.11s. Many would even make the leap to 4.88s.

 

[Broncobowsher]

To stir the pot a little more, there is a Mazda M5R2 from an F150 (typically the '97-'03(?) 4.2 V6 4x4 has all the right parts) and it will bolt straight to the V8 engine without any adaptors. Adaptor only needed for the transfer case. Another 5-speed option.

For gearing, my rule of thumb for this is to set the highway RPM for 2100+-100RPM at 60 MPH. That works really good for an overdrive transmission. You can do most of your highway driving in OD and only need to drop for passing or big hills. Don't try and cheat yourself and think you can go with a lower RPM and get gas mileage, you will be lugging the engine getting worse mileage and having to downshift on every hill further reducing the mileage. When you do the math, round up. If the math says 4.38, the next ratio of 4.56 is the one to get. That will set up the non-overdrive gears to be fun and peppy around town.

 

[rockinrich]

Thanks paul,great info,so a slight edge to nv3550 because of the lower first gear,and yes the new bronco has a granny gear in that 7 speed manual,wonder if one could buy that directly and would it fit? As far as the 5 questions,#1 i would say mostly street but want it off road capable,#2 i was thinking 33's but if i need to change some things anyway i might go up to 35's,#3 my engine has 88,000 miles on it now so when would you recommend a rebuild or would you go with a crate motor?#4 i would say the heaviest things i will add is front and rear hanson bumpers and a suspension lift,and #5 that's a tough one,i want it to be able to drive on the street if needed but want it very off road capable,is that possible? Thanks again paul!

 

[rockinrich]

That's speculative. Depends on your use.

An NV3550 has 4.01, 2.32, 1.40, 1.00, 0.72 ratios. I like my 4.11s because of the NV3550's low 1st and moderate overdrive. I have a pretty fast piece of interstate I commonly travel. The 4.01 1st gear would be almost useless with anything lower than 4.11s and 33" tires.

An AX15 has 3.83, 2.33, 1.44, 1.00, 0.79 ratios. I think a 4.30 or 4.56 would work pretty well with your 33" tires. I think the ratios on this tranny are too high for 4.11s. Many would even make the leap to 4.88s.

Thank you for the info,much appreciated,do you think they are both equally as strong?

 

[rockinrich]

To stir the pot a little more, there is a Mazda M5R2 from an F150 (typically the '97-'03(?) 4.2 V6 4x4 has all the right parts) and it will bolt straight to the V8 engine without any adaptors. Adaptor only needed for the transfer case. Another 5-speed option.

For gearing, my rule of thumb for this is to set the highway RPM for 2100+-100RPM at 60 MPH. That works really good for an overdrive transmission. You can do most of your highway driving in OD and only need to drop for passing or big hills. Don't try and cheat yourself and think you can go with a lower RPM and get gas mileage, you will be lugging the engine getting worse mileage and having to downshift on every hill further reducing the mileage. When you do the math, round up. If the math says 4.38, the next ratio of 4.56 is the one to get. That will set up the non-overdrive gears to be fun and peppy around town.

Thank you very much,that's good info to know!

 

[DirtDonk]

...yes the new bronco has a granny gear in that 7 speed manual,wonder if one could buy that directly and would it fit?

Now wouldn't that just be too cool!

#3 my engine has 88,000 miles on it now so when would you recommend a rebuild or would you go with a crate motor?

Depends. How does it run now? What do you want to end up with? And will you do any of the work yourself?
A crate motor has many advantages, even including sometimes the price. It's pay and go and drive it. Has a warranty too.
A rebuilt is more fun if you do your own work, but takes longer. It's also more personal to your needs, if you're that sure of what you want. It "can" be less expensive, but in some areas machine work is no longer the bargain it once was, and there are some very inexpensive crate motors.
A general cost for replacing and/or rebuilding everything locally is easily within the $2,000 to $5,000 range. A crate motor is what? About $4,000 minimum, to about $15,000 max for a "normal" engine? Blueprint is getting lots of traction and good reports here, and they even have a "Bronco" engine model, but I don't know what they cost. The gap is very narrow though, so much of the advantage is leaning more and more to the crate motor.
Have you seen quoted prices?

#4 i would say the heaviest things i will add is front and rear hanson bumpers and a suspension lift,and

Those are actually substantial enough to add to the equation.
Especially when a rear tire carrier and full-size spare, along with most likely a larger gas tank are added to it.
So not a heavy-weight perhaps, but certainly more than stock by a few hundred pounds. And much of it hanging off the ends, where it has more effect on suspension and handling.

#5 that's a tough one,i want it to be able to drive on the street if needed but want it very off road capable,is that possible?

Yes. It's just that the more radical your modifications are when compared to stock, the "on-road" part of that gets slightly worse and the "off-road" part gets slightly better. And since the on-road is usually more important 90% of the time, and we're not teenagers with tolerance for just about anything anymore (I don't think we are!) then road manners become even more critical to keep in mind.
But they can coexist if you're careful and don't get carried away.

Paul

 

[Broncobowsher]

88k mileage, engine probably just needs a fresh timing chain and a tune up.

 

[DirtDonk]

thought the same thing at first, but really it depends on how it was treated prior. That's just at the age that if it was not treated well, stuff is going to start going south.
My '71 needed a valve job by that time. Also had ticking lifters at 50k, but the noise went away with some judicious use of oil additives. Then started to come back just about the time I decided to do the valve job.
Put in new lifters (on the old cam), timing chain, reconditioned the heads and it was a new motor!

So yeah, it's hit or miss. And to some people needing new lifters, or even a partial valve job is grounds for a full re-build or replacement.

Paul

 

[68rustbucket]

When I changed to 33’s from 31’s and 3:50 gearing, it was a noticeable difference. Then I re geared to 4:11, I got my power back.

 

[blubuckaroo]

Even thought our Bronco comes to life at about 3000 RPM, I don't like to hear the thing winding up when cruising. The overdrive gear on the NV3550, 4.11 gears, and 33" tires cruise really nicely.
My sweetie and I took a small trip last week in our Bronco. She usually reminds me when about my speed. She didn't even notice we were cruising at 75 MPH and 2600 RPM. It's that quiet on the freeway.

 

[rockinrich]

Thanks paul,well it's been in my garage for awhile as i was going to do some things to it and haven't got around to it but last time i ran it it ran strong which was about 6 months ago.I know for a crate motor for my k4 blazer,i know i know lol,runs about 3 grand with a 3 year 100,000 mile warranty.Ive never tackled a rebuild before so probably weigh the costs of both huh?#2,yeah forgot about the larger gas tank and the spare as well as the bumpers and winch.#3,yeah it's a double edged sword with on road and off road capable huh,just have to find a happy medium if you want both huh? Thanks so much paul i appreciate it!

 

[rockinrich]

88k mileage, engine probably just needs a fresh timing chain and a tune up.

Thank you very much i'll keep that in mind!

 

[rockinrich]

When I changed to 33’s from 31’s and 3:50 gearing, it was a noticeable difference. Then I re geared to 4:11, I got my power back.

Thank you for that i will keep that in mind as well!

 

[rockinrich]

Even thought our Bronco comes to life at about 3000 RPM, I don't like to hear the thing winding up when cruising. The overdrive gear on the NV3550, 4.11 gears, and 33" tires cruise really nicely.
My sweetie and I took a small trip last week in our Bronco. She usually reminds me when about my speed. She didn't even notice we were cruising at 75 MPH and 2600 RPM. It's that quiet on the freeway.

wow good to know thank you!

 

[sprdv1]

Thanks paul,well it's been in my garage for awhile as i was going to do some things to it and haven't got around to it but last time i ran it it ran strong which was about 6 months ago.I know for a crate motor for my k4 blazer,i know i know lol,runs about 3 grand with a 3 year 100,000 mile warranty.Ive never tackled a rebuild before so probably weigh the costs of both huh?#2,yeah forgot about the larger gas tank and the spare as well as the bumpers and winch.#3,yeah it's a double edged sword with on road and off road capable huh,just have to find a happy medium if you want both huh? Thanks so much paul i appreciate it!

yes you do.. just concentrate on one thing at a time..

 

[rockinrich]

yes you do.. just concentrate on one thing at a time..

I hear ya,thank you!