Bought a new set of cab bushings, original rubber style, they fit real nice but now cab is higher than box by about 3/4”.
Anyone else have this issue or just shim bed to new height?

 

Typical for reproduction rubber.

You'd be better off lowering the cab, if you raise the bed it's going to cause other problems, you'll have to raise your core support and everything else . I had this problem on my K10 so I buffed the bushings down until they were slightly high. after the settle it's perfect now. you can always shim it up later if needed, using your original bed height as the base height is the answer.

 

Hard to believe the old bushing let the cab settle to be even with the bed. Especially since the bed is mounted with metal shims and NO rubber. Is the truck all OEM or did the PO make some changes? Who did you get the bushing set from? And 100% you are sure they are installed correctly? Just going thru a mental ck list.



I would contact a vendor with the OEM part # and see what their bushing measurements are versus the vendor you got the bushing set from. To see if there is a a chance of a difference.D3TZ-1000155-B.. Absorber (rubber cushion) - Lowerradiator support and lowerfront & rear cab mounts
CARPENTER NOS OBSOLETEPARTS in Concord NC = 800-476-9653.
PARTS INTERNATIONAL in Farmers Branch TX = 888-727-0418.
GREEN SALES CO. in Cincinnati OH = 800-543-4959.
WESLEY OBSOLETE PARTS in Liberty KY = 606-787-5293.
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D3TZ-1000396-C.. Absorber (rubber cushion) - Upperradiator support andupperfront and rear cab mounts
PARTS INTERNATIONAL
CARPENTER NOS OBSOLETEPARTS
GREEN SALES CO.
WESLEY OBSOLETE PARTS

 

I've come to expect this evetime I buy bushings. I would be more surprised if they were correct.

 

I was going to replace mine because since I bought the truck, the right rear of the cab was a little lower than the bed at the "dent lines", while the left was a smaller hair higher. I bought poly, was going to install them, and reading up on it, and read that Ford tightened the originals not just to a torque value, but pulled them down to a certain level at greater torque. It seems the torque values specified in books is just retighten the original bushings without further compressing the metal washer / sleeves that are pressed together at a desired height. Think of them like crush sleeves, but for bushings not bearings. The cab is brought to the level of the solid mounted bed. My truck was pulled down too tight for some reason, but once those bushing sleeved washers are pulled together, they don't back out very easily either.

In further study, calculations, I determined that I needed to raise the right rear of the cab with just a hair over 1/8" of metal body shim (two I used added up to about 0.150" or about "two and a half sixteenths") above the steel top washer, under the steel floor of the cab on that one right rear bushing. That raised the right rear out at the body just over 1/4" It lowered that left side nearly exact 1/8". To do it for trial, I loosened my bushing bolts a few turns, jacked a little daylight on that right rear, slid my shims in above the upper washer, lowered the cab,
PERFECT.

Below is a drawing using photos as I worked out my plan, I measured, but I used simple fractions. The bolts were retightened to spec, but again as I said, that spec does not compress those sleeves any extra. My rubber was showing some age, so I added simple screw band clamps around them to act as girdles. The poly set is on a shelf, but it was bought cheap off Ebay from an estate. The polyurethane ones do not compress like rubber, the rubber OEM even have reliefs in places to let them compress easier. The poly ones are molded to the correct height, the torque that is specified just takes all play out of those as you aren't going to compress them. I measured the polyurethane ones, the tops which support the cab are pretty much exact right out of the box match how high the cab floor is up off the frame.

• Rear (rear cab floor) top bushings are 1-5/16" tall and have a molded in metal liner with lip that fits frame hole.
• Middle (firewall mounts) top bushings are 1-1/8" tall and have a molded in metal liner with lip that fits frame hole.
• Front (rad support) top bushings are 3/4" tall and have a molded in metal liner with lip that fits frame hole.

It would not surprise me that if your new rubber bushings have the cab 3/4" too high, that you have more tightening to do to set the cab down correctly, but they use those same press in place telescoping inner sleeves with washers. Again, the polyurethane ones do not compress like the rubber, so they are made to the install height.
The polyurethane lower bushing halves do the compressing to take up slack, why they are much smaller.




It just bugged me for years, but since 1986 I do not believe the bushings ever settled further as the mismatch was always there. It was most obvious as walking towards it from the rear, seeing the rear glass above the bed front. My cab's rear bushings are inboard the frame rails.

 

No changes that would effect cab bushings, purchased cab bushings from Dennis Carpenter, installed correctly.
I started with poly bushings and everything lined up well, read that OEM units gave better ride, Obviously they are thicker and thought they would settle, I have not tried “Over-tightening” them.

 

Even compressed to spec, the rubber will give more than the polyurethane ones. I decided to not use polyurethane just because of ride or noise, but I can see where the harder polyurethane would add stresses to the cab trying to flex with the frame. Might not be a big consideration on a street only truck, but there are some situations leading to some flex ... like entering the lot of a gas station or burger joint.

Anyway, the part about setting cab height from frame I believe came from a manual. They actually pulled them down past just settling.

 

Here's what my '79 shop manual says about cab mounts. Looks like radiator support mounts should be torqued to 40 lb/ft and the cab mounts torqued to 50 lb/ft. The diagram indicates to use shims on the upper bushing to adjust within a range of .83" to 1.27" for correct body alignment.

 

Thanks for all the good info, I will re-torque and measure and let you know if anything changes…might have to use the poly ones.
I spent over $200 for the “OEM” style thinking it would be a home run.