Are shims still needed after cab mount replacement?

Randy and Easton · Feb 28, 2022

Did we create more problems?

While truck was apart my son replaced all the the body mount hardware with polyurethane mounts from Brothers. The old bushings had numerous shims on both sides so he put it back together in reverse order WITH the shims. Post paint, we are starting to put hood and such on and are noticing things out of line: Fenders at cab by windshield, front grill panel fits on passenger side but is too tight on drivers side where it meets the lower fender (picture).
Should we not used the shims?

Any advice appreciated.

Randy and Easton

Big Chip · Mar 1, 2022

It's possible someone put the shims in to compensate for worn our cab bushings. I'd take them out for sure just to see where it ends up.

Randy and Easton · Mar 1, 2022

Chip, Thanks. I think I made progress after my post. My son pulled some pictures pre paint and cab supports and the fenders are almost in the exact same place. I’m now thinking the front lower grill panel might be snug from when he did the forward frame supports under radiator. Going to see if I can get under fender (Drivers) today and get to fender bolts and see if I can adjust them out just enough to get the lower panel in.

ak4life · Mar 1, 2022

Randy De Oreo said:
Chip, Thanks. I think I made progress after my post. My son pulled some pictures pre paint and cab supports and the fenders are almost in the exact same place. I’m now thinking the front lower grill panel might be snug from when he did the forward frame supports under radiator. Going to see if I can get under fender (Drivers) today and get to fender bolts and see if I can adjust them out just enough to get the lower panel in.

Not to be rude but its obvious that tge shims were put in for worn mounts, if you installed all new mounts i would remove all shims and replace as needed if needed at all before you go making adjustments....and also it may not hurt to loosen all connecting panels just a smidge to allow things to move a bit while aligning everything....not an engineer, just a guy doing a frame off and still not done...lol.

Big Chip · Mar 1, 2022

Randy De Oreo said:
Chip, Thanks. I think I made progress after my post. My son pulled some pictures pre paint and cab supports and the fenders are almost in the exact same place. I’m now thinking the front lower grill panel might be snug from when he did the forward frame supports under radiator. Going to see if I can get under fender (Drivers) today and get to fender bolts and see if I can adjust them out just enough to get the lower panel in.

I'm assuming you replaced the core support bushings at the same time but if not definitely do that too.

Keith Seymore · Mar 1, 2022

ak4life said:
Not to be rude but its obvious that tge shims were put in for worn mounts.

Not necessarily.

Shims were used on the assembly line to help with fitment (trends).

Shims were also specified by engineering to vary the compression of mounts in specific locations, to increase the stiffness and help with certain vibrations or noise. Normal people would probably never notice the difference, but the N&V engineers (with their "dog ears" and "sandpaper a$$es" seemed to be able to tell the difference.

Randy De Oreo said:
Should we not used the shims?

I've had the experience of removing front end sheet metal on my Chevelle a couple times, and I always record and re-install the shim packs exactly like they came off.

It has never worked. I always have to fine tune the fitment a little bit, using the original setup as a starting point.

K

Doppleganger · Mar 1, 2022

I think an aftermarket poly mount might have a tad to do with it also.

AuroraGirl · Mar 1, 2022

Keith Seymore said:
Not necessarily.

Shims were used on the assembly line to help with fitment (trends).

Shims were also specified by engineering to vary the compression of mounts in specific locations, to increase the stiffness and help with certain vibrations or noise. Normal people would probably never notice the difference, but the N&V engineers (with their "dog ears" and "sandpaper a$$es" seemed to be able to tell the difference.

I've had the experience of removing front end sheet metal on my Chevelle a couple times, and I always record and re-install the shim packs exactly like they came off.

It has never worked. I always have to fine tune the fitment a little bit, using the original setup as a starting point.

K

I have like 3 ice cream pales full of shims lol
metal and plastic, for everything ive no clue what all for but if i need them I guess.

Body work was my gpas thing in the early 60s, till early 70s, and he also loved to tear **** apart and itemize the goodies

Bennyt · Mar 1, 2022

Shims? or are you referring to the factory washers?

I installed poly bushings from CPP on my son's truck, 77 C10, and followed the instructions exactly which showed leaving out the factory shims/ washers and found the cab sat way too low with the trans even hitting the tunnel. Once I reinstalled them everything started to align correctly.

SquareRoot · Mar 1, 2022

Nothing aligned on my truck before or after replacing all the bushings. You're going to have to fine tune it either way. Quality control back then left a lot to be desired.

Randy and Easton · Mar 1, 2022

Thanks everyone. Core support was done at same time. Washers/Shims ? U shaped spacers is what they were and square plates. Determined fenders are the same place based on son finding before and after pictures. Worked on it for a few hours today and could not get much movement of drivers fender outward. Gonna move on to other stuff and see if a body guy we know can help. It’s just a 15 year olds project and he is just looking for the cool factor at 60 MPH so a lot gets by him thank goodness.

Thank you everyone for being such a help. I hope I can return the favor

Randy and Easton

AuroraGirl · Mar 1, 2022

Randy De Oreo said:
Thanks everyone. Core support was done at same time. Washers/Shims ? U shaped spacers is what they were and square plates. Determined fenders are the same place based on son finding before and after pictures. Worked on it for a few hours today and could not get much movement of drivers fender outward. Gonna move on to other stuff and see if a body guy we know can help. It’s just a 15 year olds project and he is just looking for the cool factor at 60 MPH so a lot gets by him thank goodness.

Thank you everyone for being such a help. I hope I can return the favor

Randy and Easton

As Rusty would say(we miss him so much?

"pix?

[older but popular pop culture reference] and [direct insult] but [redeems the insult with witty remark] because [pls show pics we show u ours]"

RIP rusty wherever you are relative to your computer

shiftpro · Mar 1, 2022

Doppleganger said:
I think an aftermarket poly mount might have a tad to do with it also.

Don't use them on your truck bro, if it's not too late already. You won't like them. You'll feel the chitter more than with rubber... and maight even make for a louder cab (road noise... sound of screaming and breaking bones as you.. well you know)

Big Chip · Mar 1, 2022

shiftpro said:
Don't use them on your truck bro, if it's not too late already. You won't like them. You'll feel the chitter more than with rubber... and maight even make for a louder cab (road noise... sound of screaming and breaking bones as you.. well you know)

You're nuts.

AuroraGirl · Mar 1, 2022

Big Chip said:
You're nuts.

Poly cab mounts are known to be haywagony although last time they are needed.

Are shims still needed after cab mount replacement?

Randy and Easton

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