Pile of Parts
Posts: 38
Joined: Sat Feb 23, 2013 7:56 pm
Ford Explorer 8.8 3.55 to K1 axle swap
• I am not an expert. The following work was performed in cooperation with an offroad design and fabrication shop.
• Searched salvage yards and located a rear axle on a 1991 Ford Explorer Eddie Bauer with Ford axle code 45 for an 8.8 3.55 gear ratio and 31 spline heavy duty axles, $125. Has same 3.25 inch axle tubes as original rear axle in 41 IHC K1. Width is 59 ½ inches between brake mounting surfaces, similar to original. The 1990-94 axles have 10 inch rear drum brakes. Wanted to retain drums rather than convert front to disc brake. Axle mounts on top of springs same as original rear axle. Differential housing is only ½ inch shorter than original rear axle housing.
• New front and rear springs were obtained from General Spring in Kansas City. They obtained factory specification build plans and reproduced original springs. Current price is $225 per spring package + shipping. This results in $550 + $82 shipping (to Florida) per axle for springs for a total of $1264 for new springs.
• Front knee shocks were still functional and retained. Rear knee shocks were removed and modern shock absorbers were installed. A shock mounting bracket was fabricated that bolted into existing holes in the frame. Finding the right shock absorbers that would work for height and load was a challenge. Since the application was for a heavier station wagon, a pickup K1 may require different shocks.
• New customizable e brake cables were obtained from Summit Racing. Lokar parking brake cable for 42-54 Chevy trucks. Lokar EC-8004U96, $149.97. It has been a challenge to get the cables adjusted just right and loose enough so the brake self-adjusters don’t adjust themselves too tight. Very important to spend time testing and adjusting.
• A new powder coated drive shaft was fabricated with a new Ford rear axle u-joint flange and the original u-joint yoke that attaches to the transmission. The drive shaft was lengthened 1 inch due to the shorter carrier and pinion offset. Your length may vary. Jack up front and rear independently to determine how much the driveshaft moves. Need to make sure the dust cap on the yoke doesn’t pop off if the driveshaft splines extend too much.
• Highly recommend replacing the rear axle bearings, seals and gearing. Even though the salvage yard rear axle allegedly had only 58,000 miles on it, and the internals looked good and turned fine, the pinion bearing fried after only a few miles of break-in testing. The internal parts of the rear axle were replaced with new Ford Racing parts.
• The rear axle brakes were totally replaced with all new parts and drums.
• It is imperative that the brakes are subjected to short distance test drives and adjustment checks.
• Once brakes are determined to work properly, perform rear axle break-in process. Short drives at highway speed, check, cool down, repeat to get gears seated.
• My K1 Station Wagon is powered by the recently rebuilt GRD214 engine, which has shown in test drives to have no problem powering the new 3.55 rear axle. Florida is relatively flat. The few small hills encountered didn’t seem to bother performance. It was a good feeling to finally be able to take off quickly from a stop light and keep up with traffic on the highway. Still performing some tweaking of the brake adjustments before attempting a top end speed test. The improved ride has been a tremendous change. The new rear axle provides more opportunity for speed, which also can result in taking curves faster than in the past. The new springs and shocks were well worth the money as the K1 handled the curves like a new vehicle. Although I don’t plan to test it too often, as Pappy Vance told me once that even though you can make that K1 Station Wagon go faster, you don’t want to drive it faster than it was designed to go.