1984 Bronco build thread

StraightSix wrote

Fuel economy report- 15.9 mpg
Roughly 140 miles at 65mph/2600 rpm with no stops that I can remember and then another 60 miles or so driving on secondary highways at roughly 55mph/2200 rpm.

Its not as good as I originally though, but still seems pretty good to me!

I think its a little lackluster on the low end now that Im back home compared to how it drove in the mountains. I was about 1000-1500 feet higher in elevation up there. Any chance that the elevation played a part and Im jetted a little lean for home?

Thanks Jim! Ill order one a let you all know how it goes.

Dane, crawling over the center console and into the driver seat first think in the morning is the only notable problem. I think its a great camping rig, I highly recommend it!


On another side note, Ive pretty much lost all desire to have a zf5 for the bronco. Initially I thought I would just have to have an OD gear. Now, 65 seems like plenty for highway cruising. And the NP435 seems to do incredible work off road and is also an excellent around town cruiser. Maybe those guys at Ford did know a thing or two..

One advantage of my “newer” Bronco is that the passenger seat slides forward. Getting stuff in and out of the back of my truck frustrates me sometimes.

Edit, clarification

Ah, I had almost forgoten that my 1990 bronco would do that. That should help!

Congrat's!  ~16 is great MPG for one of these trucks.  

I thought all Broncos of this era were like that?
Didn't Gary wrote an eight page analysis of them when deciding on a pan and console for Dads truck?

Yes, Jim, on both counts. But that was back on the other forum and many here won’t have seen it.

I keep forgetting that the forum is only three and we've been internet acquaintances for what, 12 years?!?!

March '18 was when I replaced the engine in Lil' Red.

Jim and Gary,
My 1990 broncos seats would pivot and slide forward. The 1984s seats only pivot forward.

Yes, I think your MPG is good! I would be very happy with that economy return, I'm jealous! I agree mostly with your observation of our transmissions, it is excellent around town and country roads. Not so sure about Interstates though, not when semis are steaming along at 70+MPH! Haven't really tested mine on the Interstate since the rebuild, not for any great distance anyway. On a short distance run you can stay with traffic and not be concerned with fuel economy. But my wife wants an Ikea run to Atlanta, so I guess I'll find out soon enough. To be fair, 65 isn't so slow, not quite moving roadblock, I was limited to less than that for over 200000 miles of semi driving myself... And then voluntarily stayed at that for another 100000 in my own truck when I was paying for diesel!

ArdWrknTrk wrote

I thought all Broncos of this era were like that?
Didn't Gary wrote an eight page analysis of them when deciding on a pan and console for Dads truck?

As StraightSix said, I believe you get more room on the later ones that slide. The frustration on my truck is mainly from the drivers side.

Rob- with your 3.08 gears you are probably getting a little more speed for your rpm than me, unless you have significantly smaller tires. I agree, Id love to be able to cruise comfortably with good fuel economy at 80mph. However, in the 2500 miles or so on the interstate Ive driven the thing 65 seems to be ok, with the occasional run up to 70 or 75 for the sake of defensive driving to get away from someone. More than anything, Im not sure how wise it really is to drive a truck without airbags or rear head restraint that fast anyhow. If this is the only compromise I have to make to get all of the awesome benefits and performance of the NP435, it seems like a great trade off to me! Whereabouts are you in the Atlanta area? I bounce around from Griffin to Carrollton to Cartersville with pretty good frequency.

I spent a few years 1/2 a mile or so south of that Ikea.

Yes, the rear end should lower my RPMs somewhat, the 265/75s are about 31.6" and according to Gary's calculator that all points towards about 2125Rpm at 65. I haven't really tested that. My speedo is significantly off due to the wheel/tire combo, but on a longer trip with a passenger their would be time and opportunity to do some math...

We're in Alabama, outside Bham, hence why a trip to Atlanta should be a good measure of the Interstate performance or lack thereof... But I agree, that's not a bad compromise.

We were planning a much longer trip, but my oil leak is worse following my oil pan gasket replacement. I suspect the timing cover seal might be to blame in addition or instead of the pan gasket. Anyway, I want that sorted before doing anything further than Atlanta.

Rob, you can always set a navigation app on your phone to get mph at x rpm in x gear.
If you need a reminder you can put one of those little circle florescent stickers on the gauge. (Remember tag sales??)

OP, have a look at the members map.
'Bullnose Forum's at the left of the header of any page, halfway down the list.
Matthew and a few others live around Atlanta.

Jim, I've used Google maps to figure out how much my speedo and odo is out, just not at 65... But I will. 65 is a bit faster than I like to be going on country roads, in Eddy anyway. Ideally I would like to change the gears on the speedo, but that's a project for another time.

Right, but if you have maps running all you have to do is slack at the phone to check your speed.

Check it where you're 'comfortable' and note how far off you are from indicated.
After a day or two knowing  what the speed really is will be second nature.

When you get the gear you get the gear.
Hopefully it isn't the tailshaft gear needs changing.

Thanks for the report on the trip & MPG, at 16 MPG I would be happy but we always want more

As for the NP435 I find the gear spread between 3rd & 4th to be a little to much so most of the time I split it, 3rd>3rdOD>4th>4thOD, seams to be pretty good.
Then again I have a 2.75 rear gear and 235/65/15 tires.
I also know my speedo is pretty close on the money as I have used my truckers GPS that has the speed displayed and have adjusted the speedo gears to read right.

The speed limit on the high way here is 65-70 and you know everyone is going a lot faster than that.
I stay in the right hand lane and do between the 65 & 70 speed limit and enjoy the ride.
The secondary roads is 45-55 and again they go faster than that. Again doing the SL and enjoy the ride.

As for the 55 MPH SL back then my truck runs 1800 RPM with out the over drive.
I can now do 70 MPH at the same 1800 RPM just pushing more air out of the way LOL.
FIY 80 MPH non-OD is 2800 RPM, OD is 2200 RPM and it will cruse at 75 MPH like nothing.
Dave ----

Hey guys!
its been a long time, so I thought Id give a quick update. Im still getting roughly 16mpg highway on my longer trips back and forth to the mountains. The bronco has been on several fishing/camping trips in the last few months as well as doing a lot of work in my yard. I cant call it a toy anymore! Between the winch and some snatch blocks it pulled out a pile of trees and bushes that wouldn’t fit inside a 2 car garage even if you packed it with a bobcat. Many of those trees came out with root balls 2 ft wide. I was really impressed by what it can do.

 

I took the top off for a few weeks when we had a warm spell! Ive never had a convertible or a jeep or anything like that before so having the top off in the bronco is super cool.

 



 

I did fluid changes in the np435 and the np208. I used redline mt90 in the transmission, and it took slightly less that 1 gallon. I know there is some confusion on the quantity needed for the np435. What came out of the transmission looked like chocolate milk. Who know what it was or how long it had been in there. The transmission always shifted smoothly, but it got noticeably (only to me) smoother with the fluid change. Additionally, it occasionally refused to go into 3rd  before the fluid change, but after the fluid change I haven’t had that problem even once in several thousand miles.

 

I was able to install the “90s style” coolant reservoir, and it was really pretty easy. I only had to make minor modifications to the feet on the reservoir to get it to slide into the original mounting pockets in the engine bay wall. Because it is offset farther out from the wall, you need something to support the bottom so it wont rock and pivot all the time. Ill try to get a photo of that!

 

My speedo died on me a few weeks ago, and I was dreading pulling the cluster again. Luckily, I decided to crawl underneath first and as it turns out the speedo cable was no longer in the transfer case. The retaining bolt must have fallen out. Easy fix!

 

By and large, the bronco has been extremely reliable over the last few months with only one known issue. I was using the winch to pull out a bush in my Girlfriends parents yard. While rolling the cable back up after finishing the pull the bronco sputtered and died. Sounded just like running out of gas. I immediately pulled the carb and worked the throttle – the pump shot was still shooting fuel into the bore. So I assume that the bowl didn’t run dry of fuel. After that I assumed it was probably related to the ignition system. I picked up a new ds2 box (parts store brand) and a new coil. I swapped the ds2 box in, it wouldn’t crank. So I put the original ds2 box back then swapped the coils. That got it to crank up and drive home. The next day I ohmed the old coil and it was nothing alarming, about 2-3 ohms, I think? At that point, I was operating under the assumption that the coil was failing at temperature for some reason. I wrote it off as a solved problem. Then the next day it died in my driveway while winching in my yard (new coil, old ds2 box). It died after running, mostly at an idle, for about 1.5 – 2 hours. After cooling down with the hood up for about 1.5 hours it cranked up fine. This exact pattern repeated several times. One night my Mopar buddy was over helping out. After about 30 minutes of run time we used the IR gun on the carb flange, the coil, and the ds2 box, and we measured battery voltage before starting winching. About an hour later it died, so we remeasured. Batter voltage was down .5 volts or so but still around 13. The only temp that changed was the coil going from about 170F to about 190F. the ds2 box was at about 125F for both measurements. we pulled number 1 plug and it was slightly fouled, as if it had been running rich. We planned to ground the plug to the frame and see if the ignition system was firing but I suggested we put it all back together first to see if it would start before we assumed that our “no run condition” was still in effect. When we got the plug re-installed it started right up. So, now I have another opportunity for testing. Next time it fails Ill ground a plug on the frame 1st thing to see if its even firing. It only does this when sitting at idle for long periods of time. More updates soon!

 

Here are some of the projects I see coming in the near future –

-Wheel bearing job for the front axle

-headlight relay upgrade

-Fix the tailgate (handle no longer reliably operates latches)

-radio/radio bezel/climate control/rear glass switch general fixin’

-door and window seal kit

- strip and repaint the tub at some point?? It needs to happen, not sure when.

 

I hope you are all doing great – John

 

Bronco front receiver writeup –

As promised, here is a basic write up on my front receiver hitch for my bronco. Im sure there are stronger ways to do this, but for my goal of mounting a winch for straight line only pulls and generally light duty conservative use, it seems to be fine. While winching in my yard, I put enough tension on the cable to slide my bronco across my paved driveway with the brakes locked up. Im assuming that’s about 2500 – 3500 lbs. Beyond that, I dont have any wisdom on the strength of this thing.

 

I wanted to be able to mount or remove my winch from my bronco with a minimum amount of effort, and I also wanted to be able to leave my factory bumper in place and (mostly) unmolested. Those are the constraints the drove my decisions for the front receiver.

 

Step 1 – find a class 3 receiver. I got lucky, this one was in my grandfathers yard. You will want it to be roughly as long as the distance between the outside faces of your frame rails. You will need cut off the original mounting brackets/hardware so that you have just the tube body. The shorter the actual receiver tube is, the better. This whole thing has to live between your radiator and the bumper. There isn’t much extra room so the longer that receiver tube (the part the runs perpendicular to the axles after installation) is, the farther it sticks out of your bumper.

 

Step 2 – remove your bumper. Set aside. I cut this bracket. I didn’t really like it, but I don’t see any way around it. You may also have to relocate one of your horns, I had one living down there right behind the bumper.

 



 

Step 3- I cut out two flat plates from 3/8 steel that just fit inside the frame, marked them against the holes that are already in my frame (I didn’t do any drilling in the frame), then drilled the holes in the plates to allow me to bolt them to the frame. Cut a piece of 3” quarter wall tubing that is in the neighborhood of 8” to 12” long. The idea is that the 3” tubing will slide and “telescope” over the 2.5” tubing the receiver is made of, thus allowing you to collapse the finished product and fit it in between your frame rails.

 







 
Step 4 – carefully measure the lengths that you need the tubing of the receiver to be cut at for each side. I would recommend getting your square plates bolted into the frame and then directly measuring the length between them. You want the distance from the center line of your prefabbed receiver to one end of its 2.5” tubing to equal ½ of the distance between the square plates. You want the distance from the centerline of the prefabbed receiver to the other end of its 2.5” tubing to be shorter by a few inches so that the “telescoped” assembly will fit in and out of the frame. Measure again, make your cuts.

 

Step 5 – with the square plates bolted in exactly as you intend for them to be permanently, slide the 3” tubing over the short end of the receiver then lift the receiver and 3” tubing in between your frame rails and go about positioning it to the square plates in a way you are happy with. Remember that you need to leave enough clearance around the tubing for a weld, so the tubing cant sit directly on your bolts. Once you are happy, use your 3rd arm (or a buddy) to tack weld each corner of the 2.5” tubing to its square plate. Repeat on the other end with the 3” tubing.

 






Step 6 – remove the bolts, telescope your piece so you can get it out of the frame, and finish welding the plates to the tubing. Id recommend slowly stitching around to avoid warping the plates, but Im no welder. YMMV.

 

Step 7 – paint? I did.

 

Step 8 – you can probably find a smarter way to do this that how I did it. Essentially, its time to cut the hole in your front bumper for the receiver tube to peek out through. I parked the vehicle on reasonably flat and level ground (my garage), then installed the new receiver. I took measurements from the floor for height and from the bolt holes in the front face of the frame for left- right placement.  Then I removed the receiver and installed the bumper. Then I drew my measurements of the location of the receiver into the bumper with a sharpie marker. It is probably easier for the sake of fitting and cutting to allow for the hole to be a little larger than needed. Once I had my measurements I drilled each corner then connected the round holes with a small diameter cutting wheel. I was worried about scorching the chrome, so I moved fairly slowly and alternated side to side so that no particular part would get too hot. It seems to have worked. After you are done, you can clean up with a file.

 

Measure twice, cut once! Doh!

 
Step 9 – reinstall and weld the 2.5” tubing to the 3” tubing. This makes it essentially permanent. The only way to remove it will be to cut it out.


Step  10– reinstall front bumper.

 

In my case, my receiver is short enough that it only protrudes through the bumper about a quarter inch. If I ever get around to taking off the winch Ill just hang a vanity plate over it and itll be like nothing happened.




 

John, nice looking Bronco.
Not sure if this will be of any help but I had an 86 F150 with a 300 that had an intermittent dying condition.
I finally traced it to the ignition pickup coil, every now and then it would just quit, replaced the pickup coil and it never quit again.
Good luck
Bob

Bob,
Thanks! Thats a really excellent guess. As far as the ignition system goes, Im not sure how many other options are left. My neighbor suggested the same thing. Id like to verify that its an ignition system failure first, but that may be my next move if it is!

Nice writeup!  Well done.