The Stovebolt Site Forums The Shop Area Paint and Body Shop Floor height above frame

Just doing a sanity check here. Spent quite some time perusing threads and in several there are references to the height the cab floor should be above the frame.

I checked the FAM and unless I am going nuts I think the height is 1.88 inches. Frame at 10 and floor at 11.88.

Each of the threads I saw talked about the height above the frame either being 3/4 inch and 7/8 inch??

I don't expect it to be EXACTLY 1.88 inches but the difference between that and a possible 0.75 is quite large.

Paul

The FAM Section 1, Sheet 3.09 specifies 1.83 to 1.89 between the top of frame and the bottom of the floor panel at the front cab mount, but Section 1, Sheet 3.12 calls for 0.76 to 0.82 between the top of frame and bottom of floor panel at the rear shackles. Maybe the cab floor isn't parallel to the frame. The frame normally would set nose down just a touch with an empty truck. I think the reference dimensions on Section 1, Sheet 1.07 showing them parallel is likely for reference only.

Look it up in the CHEVROLET TRUCK SHOP MANUAL. It lists the measurements and what part of the underside of the cab to measure off of.

Thanks, not sure I am really much clearer. The 1.88 I derived from Section 1 Sheet 1.07 as you rightly mention. It does seem to be fairly specific.

Three measurements in three areas. I guess I will measure all three locations and see what I come up with. The two measurements you quote are to the floor bottom but the difference being to the bottom as opposed to the top should be minor.

Thanks for adding your input.

The front cab mounts in the frame are basically flush with the top of the frame and the cab reinforcement that supports the mounting bolt loads is approx. 3/4" deep in the area above the frame. There is a rubber pad between the two so 7/8" to the bottom of the cab in that area should be pretty close. I used a piece of 1x4 set on the frame to provide an initial elevation during the installation of the rear cab mounts. Note that the bottom of the cab has a lot of different heights so it is important to measure in the specified location.

Here's the blurb from the service manual. It's page 1-3.

Thanks guys, I had to cogitate a little on this and see now that the 1.88 quoted in the FAM Section 1 Sheet 1.07 simply cannot apply to the whole floor as it has different levels throughout.

This allows me now to perform measurements to see how in spec the body is, thanks again.

Paul

Many thanks! seems I was posting above as you posted also.

I can tell you this. Not adhering to these precise measurements will throw off the gap between the lower radiator support and the front crossmember. This gap is what dictates the alignment height of the front fenders.
I slight error at the cab mounts will be magnified exponentially at the front crossmember, leaving you with no way to make the front fenders fit right.

I agree with you Carl, but the error would be magnified proportionally, not exponentially.

I like exponentially. "Proportionally" is too easily dismissed by the casual reader. A minor mistake with the cab-to-frame specs causes monumental problems when trying to align the front clip. (I hope that you are cool with "monumental". I won't be editing that either.)

Many of the front clip issues which I have been personally contacted about are due to bad cab mounts or improper cab-to-frame specs.

I'm good with "monumental".
I was just trying to be mathematically correct.

I feel like beating a dead horse today.
Since you may well be our resident mathematician (That position pays more, so you may be due back pay from the administrator) I have a question for you.
If the distance between the front cab mount to the front radiator support is longer than the distance between the front cab mount and the rear cab mount, would that lead to a "proportional" effect (one to one ratio), or an "exponential" effect, whereas, as the misalignment along the vertical axis of the cab mounts becomes greater, the misalignment measured at the front radiator support increases by a mathematically increasing amount which is not proportional to distance measured at the cab mounts?
I believe that we have ventured away from mathematics, and have entered the realm of geometry.

I'll get my stick out and beat the horse a bit more as well.

Might be trigonometry, rather than geometry, although the two fields are related. But both are mathematical.

When I said proportional, imagine that two flat surfaces are set at an angle to each other. If one edge of the surfaces are touching, and a foot away, are 1 inch from each other, then 12 feet away from the touching edges would be 12 inches away. The proportional increase is 12 to 1.
An exponential effect would be if one of the surfaces was not flat but was parabolic shaped. The curve of that surface would be described by Height = Length ^2 (or squared), with the 2 component being the exponent. A cab/front clip would look pretty weird if it was parabolic.

Please ask John about that back pay. Thanks.

Check is in the mail, I'll bet. I am sure he is monitoring this thread in anticipation of locking it down, and pressing charges for inserection and whatnot.