Ford Explorer 8.8 3.55 to K1 axle swap


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Post Thu Feb 08, 2018 1:08 pm

Ford Explorer 8.8 3.55 to K1 axle swap

Rear axle swap 1991 Ford Explorer to K1 IHC K1 Station Wagon (should be similar for pick-up body)
• 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.
Attachments
Rear axle 1 Medium Web view.jpg
Driveshaft attached to 8.8 rear axle
Passenger rear axle  Medium Web view.jpg
Rear axle and shocks attached
Lokar e brake yoke attachment Medium Web view.jpg
Lokar e brake yokes attached to e brake lever
Loaker e brake frame bracket Medium Web view.jpg
Lokar e brake cable
Driver rear view axle Medium Web view.jpg
Ford 8.8 3.55 rear axle installed

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Post Thu Feb 08, 2018 1:55 pm

Re: Ford Explorer 8.8 3.55 to K1 axle swap

I was given an Explorer disc brake axle. I replaced, rotors, calipers, lines and hoses, internal parking brake parts, changed gear to 4:10 from 3:54, all new bearings and seals. By the time the axle was finished, I had spent $1365. I was given a pressed aluminium gear cover from a Lincoln 8.8.
I added a Gear Venders overdrive to reduce engine RPM on the highway.
Attachments
exhaust up &over (2).jpg
Gear Vendors Over drive
Left rear suspension 2.jpg
totally ceramic exhaust.jpg
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Post Thu Feb 08, 2018 4:29 pm

Re: Ford Explorer 8.8 3.55 to K1 axle swap

We cheapos do it a bit differently. No new spring packages, just use the extra springs from the years of collecting this stuff. I'd take a tape measure and just keep measuring "the herd's" differentials until a good candidate showed up, although the Ford Explorer rear end is a great find.
I cut my own driveshafts, certainly not rocket science.
Thanks for the pictures! Out of my price range!

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Post Sun May 27, 2018 1:07 pm

Re: Ford Explorer 8.8 3.55 to K1 axle swap

Also posted in Diamonds in the Rough forum. I need to find a new home for my original K1 rear axle.
1941 K-1 Rear Axle with low mileage drums and brakes. Attached custom made e-brake cables are also relatively new. I recently removed this rear axle to update my K1 with a modern Ford rear axle. Suspension shop said the pinion bearing may need replacement sometime, it was working fine when rear axle was removed from vehicle. The rear axle is in Inverness, Florida, about 1 1/2 hrs North of Tampa near the Gulf coast. Make me an offer. You will need to pick up or arrange shipping.
Attachments
IMG_4497 Small Web view.jpg
Original rear axle Medium Web view.jpg
IMG_4498 Small Web view.jpg
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Post Mon Sep 02, 2019 10:13 am

Re: Ford Explorer 8.8 3.55 to K1 axle swap

To those who have done this swap:

How did you manage the pinion offset of the Ford Explorer's 8.8? I understand that the pinion is shifted 2 inches laterally towards the passenger side.

Did you maintain the original Ford Explorer spring perches? I understand that the spring perches on the Ford axle are wider (2.5 inch spring on the Ford vs International's 1.75 inch) and the perch mounting spread is different (Ford Explorer spring perch 38.5 inside to inside whereas International K1 is approximately 41 inches inside to inside).

Did you re-use the original international springs or use springs from another vehicle? The international springs are 1.75 inches wide and 51 inches long (measured eyelet to eyelet along the main spring), 24.5 inches from the front eyelet to the center pin (A measurement) and 26.5 inches from the center pin to the rear eyelet (B measurement). With the bed on the truck but nothing in the bed (K2 with a 8 foot bed), I estimate the spring arch (C measurement) to be approximately 5.5 inches as measured from the top of the main leaf to a hypothetical line spanning from eyelet to eyelet. In the noted configuration, the rear shackle is vertical.

How did the slightly wider axle fit within the rear fenders? I understand that the wheel mounting surface on the Ford Axles are approximately 2-3 inches wider than the International rear end.

As of right now, I plan on swapping in a Ford Explorer rear axle from a 1995-2001 in order to secure disk brakes, better gearing options and posi/limited slip. I also plan on cutting the axle down 2 inches on the driver side in order to re-align the pinion to center (using an extra passenger-side axle shaft). This will also bring the wheel mounting surface width closer to the original International rear end. At this point, I plan on fabricating new spring hangers (front and rear) that are wider and include a wider shackle to accommodate wider springs AND offset the spring to match the Ford's spring perch location.

Springs from the rear of a 1995 - 2005 Blazer, Jimmy, Envoy, or Bravada seem like good options:
https://www.generalspringkc.com/product_p/22-1017.htm
A: 24.5 inches (same as stock International)
B: 27.5 inches (approximately 1.0 inch longer than stock International pushing the spring hanger to move from vertical to a slanted position)
C: 6.5 inches (approximately 1.0 inch taller than the stock International springs after nearly 80 years of life, I expect that this will be close to original)

Alternatively, springs from the rear of a 1975 - 1991 E100 or E150 seem like another good options with some additional load capability over the previously noted option:
https://www.generalspringkc.com/Leaf_Springs_Ford_Van_E100_E150_1975_1991_s/1887.htm
A: 24.875 inches (approximately 0.375 inch longer than stock)
B: 27 inches (approximately 0.5 inch longer than stock International pushing the spring hanger to move from vertical to a slanted position)
C: 6.5 inches (approximately 1.0 inch taller than the stock International springs after nearly 80 years of life, I expect that this will be close to original)

Here's another link with some information related to swapping in the Ford Explorer 8.8:
https://www.therangerstation.com/tech_library/Explorer8_8.shtml
2006 Subaru Impala WRX Wagon (daily driver)
2001 Ford F150 Supercrew (hauler)
1985 Ford F150 (donor)
1941 International K2 (project)

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Post Mon Sep 02, 2019 1:04 pm

Re: Ford Explorer 8.8 3.55 to K1 axle swap

I think most remove the old spring perches from the axle and weld new ones on in the correct position and size for the original IH springs. The additional 2+ inches in width generally is not an issue, and can be dealt with by having a slightly deeper "offset" on the wheels IF you are using different wheels than originals. Keep in mind that if you go with wider springs and perches on the axle, you will need wider on the frame, thus more work? The offset of the pinion, I am not really familiar with, but do not think it would be that much of an issue if in the same attitude as the original, the u-joints should accommodate it I would think, but then, others who have done this will speak up. Your truck is a "fat fender" truck and the original wheels and tires set inside those fenders nicely and an extra inch plus should make no real difference in the looks. Just my thoughts and opinions.
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Post Mon Sep 02, 2019 1:42 pm

Re: Ford Explorer 8.8 3.55 to K1 axle swap

lbesq wrote:I think most remove the old spring perches from the axle and weld new ones on in the correct position and size for the original IH springs.


Agreed. Doing this requires that you ensure the pinion angle is set properly (as opposed to expecting that the pinion angle / spring perch placement is appropriate for the vehicle that the axle is being swapped in to). Not a monumental task but one that I would prefer to avoid if possible, but at what cost?

lbesq wrote:The additional 2+ inches in width generally is not an issue, and can be dealt with by having a slightly deeper "offset" on the wheels IF you are using different wheels than originals.


Agreed, although this could lead to having two different wheel offsets (front vs rear depending on the front end configuration), which although works may not be practical (having to carry multiple spares, not being able to rotate tires front to back).

lbesq wrote:Keep in mind that if you go with wider springs and perches on the axle, you will need wider on the frame, thus more work?


Agreed. New spring brackets and hanger/shackle would be needed to accommodate the wider springs. Going to wider springs, something more standard than the oddball International springs, may yield other benefits such as having more options and more off-the-shelf replacement parts. I would rather fabricate new spring hangers and install new springs than grind and re-weld the perches but this is just my personal preference. It's a moot point if the pinion angle is drastically different from donor to stock.

lbesq wrote:The offset of the pinion, I am not really familiar with, but do not think it would be that much of an issue if in the same attitude as the original, the u-joints should accommodate it I would think, but then, others who have done this will speak up.


Looking in to it I am concerned that a typical U-joint may not be up to the task. Will they fail on the test drive? In 500 miles? In 5000? What sort of life of the u-joint is acceptable to me? If I don't account for the pinion offset and shred u-joints every 50 miles, I have to redo the entire swap to correct the issue. "Better safe than sorry" or "run it until it breaks"? Here's a link with some additional details:
https://www.dragzine.com/tech-stories/pinion-offset-guide-and-how-to-with-chassis-engineering/

lbesq wrote:Your truck is a "fat fender" truck and the original wheels and tires set inside those fenders nicely and an extra inch plus should make no real difference in the looks. Just my thoughts and opinions.


Thanks for the comments. I wouldn't mind hugging the inner fenders a bit tighter but I am concerned about the pinion offset. I will continue to research and will provide an update but welcome other's input in the meantime.
2006 Subaru Impala WRX Wagon (daily driver)
2001 Ford F150 Supercrew (hauler)
1985 Ford F150 (donor)
1941 International K2 (project)

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Post Mon Sep 02, 2019 2:21 pm

Re: Ford Explorer 8.8 3.55 to K1 axle swap

The pinion offset is not a problem. Ignore it and carry on. 10,000, 8.8 Ford axles are in repurposed service. My old Ford has the 8.8 pinion offset.
Attachments
8.8 rear in ther, really.jpg
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Post Mon Sep 02, 2019 2:47 pm

Re: Ford Explorer 8.8 3.55 to K1 axle swap

nikkinutshop wrote:The pinion offset is not a problem. Ignore it and carry on. 10,000, 8.8 Ford axles are in repurposed service. My old Ford has the 8.8 pinion offset.


Thanks for the comment. How many miles have you put on the u-joints with the offset? The picture you attached is a bit small to tell, what kind of joints do you have at the axle end and at the transmission end? What kind of transmission is your rear axle mated to?
2006 Subaru Impala WRX Wagon (daily driver)
2001 Ford F150 Supercrew (hauler)
1985 Ford F150 (donor)
1941 International K2 (project)

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Post Mon Sep 02, 2019 3:40 pm

Re: Ford Explorer 8.8 3.55 to K1 axle swap

Standard U-joints. The transmission is a Ford C4, not seen in the picture. What you see is a Gearvendors overdrive. How many kilometers? About two kilometers. The Ford has not left the neighbourhood.
In your mind, picture the off-set in vertical rather than horizontal. Then it becomes easier to not think of it as a problem. Thousands of these 8.8s have been repurposed and never give a problem. One of the mechanics I worked with put an 8.8 in his 1956 Mercury pickup. He has been driving it since before I retired 15 years ago.
I cannot easily see the picture on my smartphone, but I can drag it to a larger size on my touch-screen desktop.
If you need more information, the guys at Inland Empire, https://www.iedls.com/ , might help you. Ask your questions as if you are a prospective customer.
I would rather have tools I do not need than to need tools I do not have
“Never argue with stupid people, they will drag you down to their level and then beat you with experience.
Mark Twain
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