47-55.1 Cab mount question

[crushermechanic]

Can anyone tell me how thick the cab mount spacers are on a 51 3100.

[dsraven]

here is a link that may have some specs if you dig through it. at the bottom of each page you are able to go to the index and pick another year thats close. some years have more info than others. an assembly manual would give that info if anybody is "watching" and has one they could look it up for you. been awhile since my last AD episode but I seem to remember a rear cab mount shackle like a leaf spring would have, I just don't remember the front mount, it seems to me the front mount is simply some rubber insulator between the cab and frame with metal washers for shims? there will be a dimension between the frame and cab in the assembly manual for sure. not sure if the old cars manual project will show that or not.

http://chevy.oldcarmanualproject.com...to/51index.htm

[crushermechanic]

I didn't think about the assembly manual I have one somewhere. I am building solid rear mounts. The original mounts are shot and I am not a fan of them.

[dsraven]

Yeah, good idea. Check to space required off the frame then use a stock body mount from something newer or a urethane mount from energy suspension or maybe a stock mount from a 55-59 if you wanna stay old fashioned, nearly period, correct. I have used energy suspension stuff before with good results. Use silicone brake grease on them so they dint squeak.

[mr48chev]

If you are running the stock frame you just need the measurements for the cab floor off the frame rail.


It reads .78 between the top of the frame rail and the cab floor.

I've been thinking about doing the designing for a while and this is what I came up with,

Fab the bracket so that it allows for the rubber or poly cushion and leaves space for shims that you make.


The revised (if you can call it that uses the two bolt holes that you would use to attach the stock shackle mount to the cab floor with a rubber/ poly mount . I used 55/57 Chevy Motor mount biscuits for the body mounts when I put my 51 Mercury body on the 75 Monte Carlo frame and that worked well. They are easy to find, and not expensive.

A guy would have to do a bit of trimming to get two of them to fit side by side with that bolt pattern though.



It should be pretty simple to lay out the holes for the bracket to the cab. One could make the bracket a bolt on unit if they wanted to. I'd rather leave a bit of space and have to add shims to get it to the correct height rather than find out that I had the bracket too high on the frame and needed to make changes.

[crushermechanic]

That's very similar to what I built. I used 1/4 flat bar. I have some rubber I got as a drop at the hose shop I am going to make spacers out of. Hopefully I will be able to fit everything next weekend.

[mr48chev]

There are a lot of things that a guy/gal could do for the rubber/poly part. I've cut sidewalls out of junk tires to make the rubber pads for the core support more than once and a few layers could make the pad there if you had a couple of layers on the bottom ide of the bracket too.

If there is an industrial plastics shop close by they probably have left over pieces of poly material similar to the poly motormount or chassis bushing that you could get pretty reasonable.

[fauXGT]

I posed the question of mounting a 6400 cab with stock rear swing body mounts to a 3100/3600 frame, being they have different bolt patterns, on one of these truck sites needing bolt patterns, and someone responded with their version of the 90deg bracket. Solid bracket with poly or rubber top bushing.
A bit of custom work for something different.

[mr48chev]

Originally Posted by fauXGT

I posed the question of mounting a 6400 cab with stock rear swing body mounts to a 3100/3600 frame, being they have different bolt patterns, on one of these truck sites needing bolt patterns, and someone responded with their version of the 90deg bracket. Solid bracket with poly or rubber top bushing.
A bit of custom work for something different.

Either that or you have to use the top piece off the 6400 and the bracket that bolts to the frame off a 3100/3600. I think the only difference is the location of the holes in the bracket.

I didn't know that there was a difference between the brackets on 3000 series and 4000 and up until someone posed the question one day and I went out and looked and then happened to look at the image I posted in an earlier post. Since I am stretching my cab and moving the cab mounts back 9-1/4 inches it is just as easy to make the brackets as figure out where to drill new holes . I don't plan to take the truck across any rough fields when it is done but may have to grade my driveway so the truck won't get hung up.

[fauXGT]

If you are stretching the cab, are you also lengthening the running boards or shortening the bed.
Or no running boards... that meet up with the rear fenders.
I just judged the space between the cab and running board to set the straight to staggered bolt hole difference against the frame.

[joedoh]

Originally Posted by fauXGT

I posed the question of mounting a 6400 cab with stock rear swing body mounts to a 3100/3600 frame, being they have different bolt patterns, on one of these truck sites needing bolt patterns, and someone responded with their version of the 90deg bracket. Solid bracket with poly or rubber top bushing.
A bit of custom work for something different.

was it me?

[mr48chev]

Originally Posted by fauXGT

If you are stretching the cab, are you also lengthening the running boards or shortening the bed.
Or no running boards... that meet up with the rear fenders.
I just judged the space between the cab and running board to set the straight to staggered bolt hole difference against the frame.

Using a GMC long bed frame stretching the cab 9-1/4 inches, Using long bed running boards and the stock length short box.

[fauXGT]

Originally Posted by joedoh

was it me?

I think....yep.

[fauXGT]

Originally Posted by mr48chev

Using a GMC long bed frame stretching the cab 9-1/4 inches, Using long bed running boards and the stock length short box.

Kool. I was only looking at adding 5" to the cab. Great idea about using long bed frame and standard bed. At that length of a stretch, you could have that seat so far back you can squat sitting and barely see over the dash, elbow out the window and cruise.

[Tempest67]

I know this sounds really 'Canadian', but I have seen people use hockey pucks for body mounts

[mr48chev]

Originally Posted by Tempest67

I know this sounds really 'Canadian', but I have seen people use hockey pucks for body mounts

I've heard of them using them for motor mount biscuits. I don't know how much flex or give a hockey puck has though.

Most of us don't need the flex and give that the shackles provide because we just are not going to intentionally go bounding off through a rough pasture with our trucks as they were intended to do when they were built. I may have to grade my driveway just to get in and out as I have some real nice tank traps in the driveway that keep some individuals out .