Question! Rear Wheel Well Repair

[gdbeckst]

Hi everyone,

One of the few projects I can tackle while the weather warms up is repairing the rear wheel well liners.

I have early style ones made of polyethylene, as per the workshop manual. For reference, I measured it to be 1/4” thick and it seems like HDPE (as opposed to LDPE), it is very rigid.

Anyways, GM changed the design and material (to fiberglass) on later coaches. This was due to an issue with the earlier design: under extreme circumstances (like when the rear suspension is complete deflated), the tires could rub/rest on the rear wheel well liner.

In my case, this is evidently what happened and caused the liners to crack in several places, see attached.

I’m planning to use a hot stapler to join/reinforce the cracks, and then a hot air welder to weld them together for a water-tight fix.

My question is this:

Can someone take photos of their later style (75+ I believe) rear wheel wells? Could you also measure the dimensions of the “divot” GM added over each wheel?

While I’m repairing the wheel wells, I am considering modifying them with some sheet material to add the clearance humps from the later design.

 

[tmsnyder]

I wish mine were in my driveway for you to stop by and look at. But it's in winter storage about 4 hours away. I know where there is one nearby in its own garage, I'll PM you his number, I'm sure he'd love to talk with you

 

[ScottC]

I had the same issue but I was lucky enough to find newer style wheels to swap in, hope these photos help. If you need anything else just let me know.

 

[RoadWarrior]

You can use hot glue to repair HDPE since it is LDPE. Its a little softer but patches well. There are also special epoxies that are said to bond well to HDPE, although I have not tried them. Most latex paint buckets are made of HDPE and with a little work with a heat gun, pieces can be formed into shape.

Although I have the later style wheel wells (77') I gave them several coats of Herculiner. I found a tip on this online to keep from having a tire separation keep from tearing up the wheel wells. This made them much tougher.

 

[gdbeckst]

I had the same issue but I was lucky enough to find newer style wheels to swap in, hope these photos help. If you need anything else just let me know.

Those are some great pictures, it doesn’t look like they added much clearance, maybe 1-2”

 

[tmsnyder]

I had the same issue but I was lucky enough to find newer style wheels to swap in, hope these photos help. If you need anything else just let me know.

Looks like they designed those to correct for unanticipated body sag, similar to the engine hatch cover

 

[Ken B]

When I saw that picture I wondered if it wasn't caused by collapsed body to frame spacers or the wrong shocks which are the stops on the upper wheel travel. The spacers are only 3/4 inch thick.

 

[gdbeckst]

So I spoke with Cinnabar, since they are the closest GMC vendor to me (a short 4.5hr trip through Ontario, Canada), about used fiberglass rear wheel wells.

They told me they don't sell them used because most of their parts coaches still have interiors in them.

But they do sell new ones. They typically use them in their own restorations. They have a mold and make hand-laid fiberglass reproductions of the later-style liners with the wheel humps. There is ~8 week lead time as they're custom order, but I kind of expect it to be done sooner. They quoted me $475/pc.

For something that's so difficult to replace (requiring complete interior removal), I'm just getting new replacements. The ultimate cost will probably be 2X what it would have cost in tools+materials to repair the original plastic liners. However, I will save a lot of time and effort in repair and ultimately have the peace of mind that an air suspension problem won't crack my extensively repaired liners...

Win-win, always check with ALL the vendors before making a decision!