Finesse 1-2-3- Ford, Part 2
Part 2- Suspension and Tires
Even with no lift, there’s room for a 12.50x33-16 or equivalent. The leaf spring TTB suspension is simple and relatively easy to lift but not a particularly supple or flexy setup.
WE CONTINUE our three-fer on the 1980 through 1986 Ford 3/4 and 1-ton trucks by talking about suspension mods and tire fitment. These trucks are remarkably forgiving on both counts. Reasonably large tires can be fitted with little or no lift and lifts are much easier than the 1/2 ton TTB coilers because the design is much simpler.
WHEELS
From the performance standpoint, lifted or not, “Job One” (pun intended) is a rim swap. Yeah, tires are usually job one, but you can't mount much of a tire on the stock 6.00x16, 8-lug rims. These are extraordinarily narrow and the more useful 7-inch rims didn't appear on stock Ford trucks until the early ’90s. In scanning the tire manufacturer’s catalogs, the factory size, LT235/85R-16 (about 32 inches tall, and very narrow) or a 7.50-16 are the only tires available that will fit these skinny O.E. rims. Anything wider tends to squeeze the beads a little too much and this results in varying degrees of poor handling and abnormal wear. Owners report that a LT245/75R-16 will fit, (it’s rated for a 6.5 inch rim, minimum) but you lose some diameter and the tire is still deformed a bit.
The stock rims have about 4-1/8-inch of backspace, which equates to a halfinch of positive offset. The odds are good you’ll go with a 8-10 inch rim and your backspace will likely increase a little to about 4-1/2 inches, with most of the extra width added to the outer part of the rim. You can find wheels with up to five inches of backspacing but at that point, tire or wheel interference with the spring gets more likely.
With the proper rims, the ’80-86 Fords will mount tires up to about 33 inches in diameter with 12.5 inches of width with no lift and no trouble. If the truck has a diesel engine and the standard spring pack up front, expect spring sag. Many of them have sagged over the years with that big ol’ thousand pound engine up there... and sagging does complicate tire fit.
We won’t tell you the style of rims to buy, but an 8-lug wheel on a beefy truck should be rated for the weight your rig must carry. Alloy or steel is also your choice. Alloy rims are lighter and will help keep the rotating mass lower. Even a mild upgrade from stock tires to a 285/75R-16 increases tire weight by 20-plus pounds, each, and a bigger steel wheel will add to that even more. Remember, the lighter the rotating mass, the better the braking and handling. Finally, a cast alloy rim is a good choice, but a forged wheel offers even more beef. If you work you truck hard, forged wheels are the better option.
Contrast the lifted angles with the stock steering angles.
FRONT SUSPENSION
The dominating feature of the ’80 to ’86 3/4 and 1-ton Ford trucks is the Twin Traction Beam (TTB) front suspension. Unlike the more familiar half-ton coil setups, they used reverse arched leaf springs with shackles at the front. All this vastly simplifies lifting them, but the leaf spring TTBs are not all that flexy. When the beams pivot down, the leaf springs tend to limit downtravel because the springs twist laterally as the beams drop and they will only twist so far. The beam axle F-350 trucks can be very flexy.
Three axle types were available, the Dana 44TTB, Dana 50 TTB and the ’85-86 Dana 60 beam axle. The springs remained largely the same on all three, and all three axles can be swapped among the group. The Dana 60 in the F-350s had a track rod for improved handling, but the spring setup and spacing was just the same as the others.
By installing aftermarket springs that are flat when mounted, rather than reverse arched, you gain 2-3 inches of lift. This will generally level the truck. A 4-inch lift puts the springs just barely down of flat (a.k.a. negative camber) and even a six inch lift doesn’t put all that much downward arch in the spring. The bottom line here is that these trucks rode well stock, (especially the diesels) and lifts up to six inches still leave the truck riding pretty good.
Superlift let us use this great illustration that shows what happens to the steering system on a 6-inch lift (top). If you used a dropped Pitman arm, the effects would be somewhat mitigated but bump steer will still be there. The Superunner steering system drastically reduced angularity and beefs up the system as well.
The Stock TTB leaf spring suspension has few vices compared to the half-ton coil spring version, but performance potential is much lower. The best idea for TTB owners needing maximum performance is a solid front axle swap.
The crucial elements when lifting these TTB trucks, or any TTB truck for that matter, are the drop brackets for the beam pivots. You have to drop the pivot points approximately the same amount as you lift the suspension to keep the geometry right. If you don’t, you will end up with way too much positive wheel camber (top of tire tilted out). This job requires punching out the rivets for the original brackets and bolting on new, drop brackets. You could modify the arms instead, but that is a very fabrication-intense way to lift these trucks.
The most important part of the lift is to make sure these drop brackets stay tight. The extra leverage they create can loosen or break the bolts, or even damage the mounting points on the chassis if the truck is used hard. In some cases, installers will weld the new bracket to the chassis. Fortunately, the leaf style TTBs are not as hard on the brackets as the coilers because their travel is so much more limited.
The pivot brackets are a very important part of lifting a TTB truck. The bolts need to be tight, tight, tight! Then they need to be checked often thereafter. The two holes for pivot points are used for different lift heights. This is actually a half-ton truck but the big trucks are largely the same.
The bushings in the pivot points are another crucial item. The original rubber ones last a long while on a stock, street driven truck, but trucks that are ’wheeled and/or lifted with big tires tend to eat them faster. For that reason, it’s a good idea to replace them with poly bushings. The only downside to poly is that they can get a bit noisy (squeaks/creaks) at times.
The solid axle D60 on the F-350 deserves a few words on its own. As mentioned before, it was available on trucks built after about February of 1985. Besides the axle, the major difference in the suspension between the TTB and the D60 is the track bar. The D60 front end is a lot more flexy than the TTB but the track bar does restrict articulation. Some owners opt to remove it and the tradeoff could be a blue oval form of the dreaded death wobble. The tendency is more prevalent with larger tires. The sway bar also restricts articulation and disconnects are available from Skyjacker and others.
TIRES
In choosing tire tread design, you’ll be ahead moneywise if you make the selection according to the terrain you see the most. If you mostly run the street and do mild off-roading, choose an all-terrain. An A/T will offer the best fuel economy, handling, braking and tire life with most of the good looks you want. The more aggressive the tread, the more rolling friction, which decreases economy and tread wear. The deeper tread of a mudder also tends to reduce braking and handling performance, but they are the winners in the dirt by a long shot.
As to size, look at the following chart for a selection of tire height versus the necessary lift. The increased availability of larger rims (e.g. 17,18 and 20 inchers) allows you to retain better handling by having a lower profile tire while maintaining a taller overall diameter. The lower profile tire sidewall doesn’t squirm around as much while maneuvering and braking, so it offers more predictable street performance. There are minor losses in the ability to air down with the lower tire profile, but the benefits for street handling far outweigh this problem for most ’wheelers.
Finally, remember this is a truck. If you use it to haul the loads it’s rated for, buy load rated tires. In general terms, a working 3/4-ton needs Load Range D tires, minimum. Many 1-tons were spec’ed with Load Range E. Beyond the D and E ratings, also look at the tire’s capacity in pounds. There are wide variations in capacity and some load range D tires are equal or better than some Load Range E.
Tire Fitment Guide
Note: This is a general guide for '80-86 Ford F-250/F-350 trucks. Popular tire upgrade sizes listed. Tires over 38 inches not listed because major axle upgrades will be required for TTB trucks. Not all sizes listed. Taken from a variety of sources.
Lift None 4-in 6-in. 8-in
Tire Most 33s Most 35s Most 36s Most 38s
285/75-16 Some 36s Most 37s 38x12.5-16
33x12.5-16.5 315/75-16 36x13.5-16 355/65-16
33x12.5-17 35x12.5-17 36x15.5-16 38x12.5-16.5
305/75-16* 325/65-18 37x13.5-16 38.5x14.5-18
305/65-18* 36x12.5-16 37x12.5-16 38.5x14.5-20
37x12.5-17
37x12.5-20
Key: *= Minor rubbing possible.
If you need mud or rock traction, the ProComp Mud Terrain is a good choice. You will sacrifice a skosh in fuel economy and street treadwear.
The BFG All-Terrain is a popular load carrying truck tire. It offers good street performance, mpg and treadwear but you will make sacrifices in trail performance.
STEERING
Another important element in lifting the TTB front is maintaining steering geometry. Ideally, you want the steering rods to follow the arc of the traction beam travel as closely as possible to avoid bumpsteer. The critical part of that arc is a couple of inches above and below ride height, which is the travel used for normal street driving. A little bump steer at low speed on the trail is manageable... but you don’t want it hitting a pothole at 60 mph.
Steering correction is a lot easier to do on a leaf TTB truck than a coiler because of the limited travel. Level one is simply the dropped Pitman arm that comes with your suspension kit. Superlift carries it a bit farther with their Superunner steering improvement kit which adds an idler arm and equalizes the tie rod lengths. This goes a long way in beefing the system and equalizing the arc of the rods and the traction beams. This setup is a boon for all TTB trucks. Speaking of tie rods, many of the truck in this era used some of the cheesiest tie rods known to man. It would be a miracle if there were still some intact, but if you have one of those wimpy setups with the crimped rubber sockets, do yourself a favor and upgrade to a stronger and better part.
285/75R-16 and 33.12.50-16 tires fit well on this era truck. In this case, the front springs are even a little sagged and the steps reduce clearance even more.
Stock TTB trucks do not come with a steering damper. Most owners do not report many adverse effects up to well balanced 33s. After that, consider an add-on steering damper kit. A single damper is sufficient except for really big tires, at least up to what the TTB front end can stand.
The power steering in the early TTB truck is notoriously wimpy when combined with big tires. With tires below about 35 inches, most owners report few problems, but a power steering cooler is very useful at preserving fluid life. Beyond 35s, hard steering while ’wheeling and a lack of power assist while parking both become common problems. The options are a lot more limited on the HD Ford trucks because they didn’t use Saginaw boxes.
Level one would be an improved steering pump. AGR, for one, offers a Saginaw P-type super pump that can be installed with modifications to your Ford’s existing aluminum pump bracket. Most of them anyway. Flow and pressure are significantly higher than with the stock pump and these two items provide the “power” in your power steering. Next up would be the addition of a rebuilt steering box. Finally, with the biggest tires you need even more assist and a ram setup becomes necessary. In the case of AGR’s Rock Ram setup, the kit includes the Ford Super Pump, a modified steering box and the hydraulic ram. The Rock Ram eliminates the need for a steering damper. This setup will turn the biggest tires.. and also bend stock tie rods like licorice. You need a tie rod upgrade!
Ford power steering is notoriously wimpy. When you get into tires above 35s, the problem can get acute. Up to that point, an upgraded pump will usually do the trick. Into the larger sizes, the most simple answer is a ram assist kit, like this one from AGR. It uses a more powerful Saginaw P-Type pump, a modified Ford steering box, the Rock Ram and the various parts needed to install it.
The factory block is about 2-inches tall. In most cases a 4-inch lift will come with a four-inch block to replace the two-incher. There are taller blocks available, but beyond about 4-inches, spring lifts are best.
REAR SUSPENSION
There’s nothing fancy here, just lots of leaf springs. Some trucks have overloads, many do not. Most trucks in this era already have what amounts to a two-inch lift block already installed. As to lifts, the most common method is via taller lift blocks. This is an inexpensive and viable alternative up to a max of about four inches. Incidentally, with a given lift height, you may not always get a block of that dimension. That’s because the rear is usually taller than the front. A four inch lift will give you a four-inch block but it will be only two inches taller than the factory block. Never, ever stack blocks to get more lift. Above a four inch block, springs lifts
become necessary. You can combine lifted springs (which simply have more arch) with a block; four inch springs with 2-inch blocks, for example, to get six inches. With blocks, you can get axle wrap problems. That is less common with HD truck springs, but a combination of big tires and lots of torque can create it. Lifted springs are more resistant. Highly arched springs are stiffer. You will no doubt hear about shackle flips, either store-bought or do-it-yourself. These turn the tension type shackles (spring is mounted above the frame bracket) into compression shackles (Spring below the mount). A shackle flip offers a 3-4-inch lift, but may create some geometry problems depending on how it’s done. That’s a story in itself, but if you find a ready made product from a reputable manufacturer, (if you can find one for the Ford) the odds are good that it will work better than trying to fab one willynilly yourself.
Because these are trucks some conversation is in order on load capacity. The first advice is that you can’t turn a 3/4-ton truck into a 5-ton truck by installing beefy springs or overloads! The axle, tires and chassis are not up for the extra load, OK? Keeping that in mind, overload leaf springs or air springs to keep the truck more level and in control with a heavy load can be very useful.
SOURCES
4 Wheel Parts
www.4wheelparts.com
800-284-9840
BF Goodrich Tires
www.bfgoodrichtires.com
ProComp Tires
www.procomptires.com
Superlift
www.superlift.com
