That looks awesome. I repaired mine only to have it crack in a different place near the original cracks within a month so I replaced it. I hope yours doesn’t do the same. My belief is that once the plastic becomes brittle there’s no stopping it.
Tahoe Z71 renovation project - Cracked Dash Fix
- Thread starter The Raven
- Start date
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The Raven
Full Access Member
Was yours laminated in automotive vinyl?
Mine wasn't particularly "brittle". I imagine many of you are finding your dashes to be close to the point of shattering due to long term sun and heat exposure, but mine is still very flexible and resilient...probably due to the truck having been garaged all its life and having 1/2 to 1/3rd the mileage of other trucks it's age. I had to bend my dash pretty significantly to get it out and did not experience any more damage by doing so. The vinyl wrap now gives it reinforcement and protection from the sun.
No vinyl. I bent it too taking it out and it appeared flexible. It was then stored under cover with no sun exposure. Im not sure why it cracked again.
Edit: my truck has 60k miles on it.
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iamdub
Full Access Member
Good job! This is exactly how I plan to fix mine except I want to reinforce the underside with aluminum angle and/or flat bar (stood vertically) and lots of epoxy. I'm currently trying to get to another member not far from me to get his like-new dash cuz he has a Escalade dash to swap in. I'll still reinforce the new dash if I get it.
The Raven
Full Access Member
You have to be careful with the idea of reinforcing a brittle part with more brittle material. Using epoxy to bond metal to it is going to do very little as the epoxy is just going to crack off under stress. Placing "columns" underneath like you describe will be a problem too because those columns will concentrate stress wherever they contact the dash cover...so it'll just break there first. You need forgiving reinforcement - I went with vinyl because it does several things in one - it adds a forgiving strength layer to the plastic so it won't just crack right along with it, it also changes the resonant properties of the plastic, so the vibrations that cause the cracks to begin with will no longer affect it at all, and finally, it looks great. Using something like high durometer rubber or foam on the underside would do the same trick, without requiring the skill that a vinyl wrap job does...however you need to bond it well with a flexible adhesive, which is also tough...off the top of my head I think the expanding gorilla glue might be a good choice for that. You could also just try completely filling the void with high durometer foam...this would take the adhesive out of the question but you have to make sure you get just the right amount of foam so that it fully supports the dash top without putting upward pressure on it.
In the end, i'm not sure there is anything that will stop these things from breaking. The originals crack, the "revised" ones crack just as bad...it's a poor design choice and there may be no overcoming that fact.
iamdub
Full Access Member
I totally get it what you're saying with rigid vs. flexible reinforcing. With the way they all crack the same way, in the same areas, it's clearly due to flexing of an unsupported span inflicting stress on the points where the support (non-flexing) begins. You either add more, but equally flexible support to that lesser-supported span or you make the entire thing totally rigid, like an I-beam. I considered adding support with plastic bags filled with something like expanding foam so it'd flow, fill in and take the shape of the underside while not actually adhering to anything. This would add support, but I don't know if it would "match" the supported areas on the ends well enough. Even then, foams tend to break down or at least expand and contract with age and temperature swings. Because of this, I figured it'd be easier and more effective to go the other way and make the whole shell rigid. By vertical, I didn't mean to make vertical columns to support it like pylons under a bridge. As you said, that would create stress risers. I want the dash shell to still move independently of the skeleton because it all flexes differently by design. I meant flipping the new shell over and using aluminum flat bars (3/4"x1/8" minimum should do it) to span end to end. The bars would be stood on edge and rested flush against the plastic. Being stood on end, it'd have way more support than if it were laid flat just like the vertical bending resistance of a beam is primarily due to the depth of the webbing. The epoxy would be to secure the flat bar in place and not to adhere the shell to the skeleton.
Wrapping it afterward would, as you mentioned, provide additional support as well as protection from the environment. If I were to keep my original dash and repair and reinforce it, wrapping would conceal the repaired cracks. If I end up with the like-new dash, I'll still reinforce it but won't wrap it unless I can find a vinyl that matches the OEM grain. I don't know what it's called, but it's more of a "cobblestone" grain of leather than the usual "cracks/veins".
It'd be great to have two different dash repair methods to test. But it'd probably be a long time before any changes would occur and there are too many variables. Also, I don't think I'd ever have a problem after this because mine stays parked inside an insulated shop 5-7 days a week. On the flip side, when I do drive it, my one mile of use is probably equal to most other's 2+ miles of use.
The Raven
Full Access Member
This is what i'm banking on too. I have the vinyl to reinforce it and some foam in the big void for basic support. But my truck has been garaged all it's life (now in a climate controlled garage too) and it's a third vehicle so it only sees maybe 6k miles a year. So i'm just banking on all of that allowing the dash to last the 3-4 years max I intend to keep it for.
I know I went through a LOT of effort including steel rods epoxied to the areas which were prone to cracking. I epoxied the hell out of it to the tune of $75 worth of the best shit made for plastic. And after pulling the dash, doing all that, reinstalling the dash it looked great. Then it cracked anyway. I seriously doubt gluing vinyl to the top of it will make any difference, hopefully I’m wrong. You can talk flexible and resonance and vibrations until the cows come home but if it’s a ************* to start with all you end up with is a prettier *************. It’s still gonna crack. It’s possible that if you take a dash skin and glue to it with enough glue it might not crack underneath it but those look like shit IMO. I give the vinyl about a 10% chance of stopping the cracking but at least it won’t show as much. Might as well just buy the new updated version of the dash. Yes the new ones are supposedly better.
The Raven
Full Access Member
The vinyl will do a better job than rigid reinforcements epoxied to the bottom. That said, I can't say that there will be an effective difference other than the fact that the vinyl will hold the dash together after it cracks. Even with those dashskins the underlying dash still cracks. Even the new ones crack, just as bad. A buddy of mine runs the city garage for the county and they have seen tens of NNBS Tahoes over the years and they were all the same - new dash, old dash, they all cracked...badly.
That's why I said it's entirely possible that there is no fix for this...and one of the reasons why I went the vinyl route - at least when mine cracks again it won't be visible and it won't rattle.
That's why I said it's entirely possible that there is no fix for this...and one of the reasons why I went the vinyl route - at least when mine cracks again it won't be visible and it won't rattle.
Oh you’ll see it. I’ve seen vinyl over cracks and it’s visible for sure. Just not as noticeable. That’s why I hope yours doesn’t crack again because you’ve put a lot of work into it.
