Help on Regearing..or tranny swap?

[Eyedoc]

New to the forum and new to Early Broncos! Just bought my first Bronco, a 1972 with 302, Ford Toploader transmission (can't identify which one; no tag) with the factory gearing of 3.5:1. It now has 33" tires on it and is a DOG when starting in 1st. I feel like I'm starting in 2nd or 3rd gear. I'm guessing its the relatively high gearing of the top loader

My question... Should I swap out the transmission or the gears? I plan to use on the road and off road (no major rock crawling) equally, but don't need fast highway cruising speeds. I was thinking of the NV3550, but I don't know enough about the top loader to know if it is a good transmission and just needs a gear swap.

Thanks for all the info and looking forward to this forum!

 

[Apogee]

Welcome aboard!

I have run my EB with a healthy 351W, but otherwise similar setup to yours with 3-speed RAT/RAN trans, 3.50 gears and 33" BFG's (that measure about 32"), and it's a rocket ship off the line, but that's the difference between a 351W and 302. While moving to an NV3550 would be a good step in the right direction, the OD would be virtually unusable without lower gears, so given your setup, I would just do the gears first and see how you like it. I would probably go 4.11's or 4.30's myself if you still want to cruise with traffic on the highways, or 4.56's if you think you might step up to 35's at some point or really don't see yourself going 65-70 MPH all that often.

I will say that off-roading with my setup above was no fun in 4-high, hard on the clutch and 4-low was only marginally better, but I could hang with the imports coming off the lights and cruise 70 MPH on the interstate without issue.

 

[Broncobowsher]

With 3.50 gears and 33" tires the overdrive of an NV3550 is worthless.

Regear to 4.10s. They have proven to be a real good match with 33s and a non-overdrive transmission time and time again.

 

[bronccar]

Yup go 4.10/4.11

I'll even sell you the D44 ring and pinion and the 9" third member with a mini spool. $350

 

[Eyedoc]

Thanks for all the great info. I have decided to try the 4.11 on the back only for now to make sure I like the ratio. Will soon after do the front. Likely will go with the NV3550 down the road. Thanks for the offer bronccar, but i'm going to go with new parts. Thanks again!

 

[Broncobowsher]

If you are planning an overdrive down the road, you may want a touch more gear now so the overdrive is useful without hunting in and out on every hill. Crunch the numbers. Think of how that 3.50 gear handles hills now and what an even taller effective overdrive will be like. 3.00 effective gearing on tall tires pushing a brick through the wind isn't a pretty sight. Plan ahead.

 

[sykanr0ng]

Thanks for all the great info. I have decided to try the 4.11 on the back only for now to make sure I like the ratio. Will soon after do the front. Likely will go with the NV3550 down the road. Thanks for the offer bronccar, but i'm going to go with new parts. Thanks again!

If you are planning an overdrive down the road, you may want a touch more gear now so the overdrive is useful without hunting in and out on every hill. Crunch the numbers. Think of how that 3.50 gear handles hills now and what an even taller effective overdrive will be like. 3.00 effective gearing on tall tires pushing a brick through the wind isn't a pretty sight. Plan ahead.

If you are going to swap in an NV3550, buy the used 4.11 gears for now.

Once you get the NV3550 you will want 4.88 gears.
(4.56 gears at the very least)

 

[DaveLev]

Welcome to the forums! I have a stock 302/2 barrel w/ 4 speed manual NP235 and stock dana 20, and 3.50:1 gears and 33 x 12.5 x 15 rims. I put a poll here online, and the results suggest 4.11/4.10 is the best for my configuration. Read more here: http://classicbroncos.com/forums/showthread.php?t=268237

 

[EB70]

A little gearing help makes 33's with a 3-speed a lot nicer. I did it and it is way easier to drive around town. I think the slightly lower 1st with a 5-speed would be nice as well.

 

[Eyedoc]

Ok, so I opened up the tranny and checked the gears. I have a toploader "close" transmission with the following ratios-

1st- 2.32
2nd- 1.69
3rd- 1.29
4th- 1.00

Why this was put in a bronco, I'm not sure. I maintain around town, but I'm embarrassed at stoplights with my awful acceleration and I will not go off road. I think the 4.10 is the way to go. Unfortunately, I think I'm looking a tranny swap sooner than later.

 

[EB70]

With that first gear ratio, I'd definitely look into a tranny swap first.

 

[DirtDonk]

...Why this was put in a bronco, I'm not sure.

Some did it because the racers did it, some because it was the 4-speed that they wanted and this was the easiest way to get it, others because it was strong. Most probably just because it's what was available when they either didn't know about the truck transmissions, or didn't think they needed the granny low (6.48 or something like that?) of an NP435.
But as you found out, the very desirable (for a car) close ratio box is a lousy match to a Bronco with large tires. Perhaps the installer still had small stock-ish tires on it when the trans was originally put in.

If you do go with the NV trans, you'll love the lower first gear, but you'll also like how much you can sell your Top Loader for too! At least in certain circles, it's a very desirable box.
But even with the poor first gear choice for a truck, changing the rear ratio to something lower will really wake things up. I would definitely go with the lower gears though. At LEAST 4.30's if not 4.56 I would think. After all, it sounds like you're really toying with the idea of 35" tires and an overdrive trans in the future. Which has a way of happening sooner than you think.
And going with the lower gears now, would likely not kill you around town either. Might make you wish for the overdrive on the highway, but those 33's are like having an overdrive already. The 35's will just be more so.

Use a chart to find your engine speed at 70 with 33's and a 1:1 top gear and you'll find out what you'd be running until you get the overdrive or 35" tires. Probably in the neighborhood of 3000 to 3200 rpm or so, which is nothing for a 302.

And remember too, 35's are not only taller, but heavier and have more rolling resistance of their own to add to what you're already dealing with. So erring to the low side (high numerically) is often a good thing.

Paul

 

[Eyedoc]

Thanks for the info, DirtDonk. Didn't even think about selling the toploader! I plugged in all the numbers and compared swapping trans or gears. Both seem that they will help quite a bit. I'm thinking I should just do both and be done with it!!!

 

[DaveLev]

I think the numbers on your existing transmission can be found by removing the tunnel cover parts. I found the "NP" stamp and a "76" on my transmission, but I could not see any other codes. I will say, however, that these NP 435 transmissions are really tall - had no idea - and when the cover was off I could do a few things I had wanted to do, such as tighten up the crossmember bolts, clean the transmission, look at linkeage on the Dana 20 to determine which type I had, and reseal the tunnel housing with extra goop so I don't smell engine fumes in the cab any longer.