If I ever get the world's slowest engine swap done, I'll be using a set of Beretta GTZ wheels on my '87 coupe. I got them at a half-price sale at the salvage yard, but only one of them still had its center cap. I've learned that GTZ center caps are rare commodities and have been searching for a DIY alternative ever since. Last week I came across a set of hubcaps from a Grand Am at the same salvage for $10. They're all one piece, but the center section looked to be very close to the size of the GTZ cap. I cut one of them off and discovered that there's a lip at the base that will fit perfectly on the GTZ wheel. Now all I have to do is figure out how to attach the hub cap centers to the GTZ wheels.
That's the GTZ cap on the left, the hubcap center section on the right.
I'm tempted to just epoxy the centers to the wheels, but maybe there's a better way. Any suggestions?
[This message has been edited by Quad Raider (edited 05-20-2015).]
My solution for my father in laws Chevelle with knock off centerlines was to have some 3d printed. If your interested you can send me the dimensions and I'd make some files for you.
[This message has been edited by jmbishop (edited 05-20-2015).]
Just use a tube of automotive silicone and let it dry for a day. Glueing or epoxying them will make them hard to remove for tire service. Silicone will come off.
Will any part of it insert from the rear of the wheel? If it will and there's enough exposed on the front, push it in and cut it off flush with the back side of the wheel. It looks like the original cap had a lip that snapped into the groove inside the wheel. Once you have it cut down to the right diameter, push it in until the bottom is flush with that groove.
[This message has been edited by fierofool (edited 05-20-2015).]
Will any part of it insert from the rear of the wheel? If it will and there's enough exposed on the front, push it in and cut it off flush with the back side of the wheel. It looks like the original cap had a lip that snapped into the groove inside the wheel. Once you have it cut down to the right diameter, push it in until the bottom is flush with that groove.
That was my hope, but this cap won't fit from the back. It needs to protrude by about an inch in order to clear the spindle but it's flush with the opening when inserted from the back.
The original cap has plastic teeth that hold it in place. I guess they break off which is why the caps are so rare.
In the picture of the hub caps, the left one has a large section removed. Was this section held on by the lug nuts? Will it fit into your GTZ wheels using the original Grand Am lug nuts?
In the picture of the hub caps, the left one has a large section removed. Was this section held on by the lug nuts? Will it fit into your GTZ wheels using the original Grand Am lug nuts?
That's where I cut the center section out. The hub caps are all one piece.
My solution for my father in laws Chevelle with knock off centerlines was to have some 3d printed. If your interested you can send me the dimensions and I'd make some files for you.
3d printed and painted. They have a low polygon count by design that you can't see in that picture(lots of flat surfaces that make up the round part) I left it that way on purpose because I wanted it to look 3d printed.
What's the inner diameter of the GTZ wheel cap opening? I have some Pontiac center caps from another vehicle that may snap in. They're black with the arrow head logo.
Here's a photo of the GTZ cap on the left. The plastic teeth must break off over time.
The outside diameter of the lip around the hole on the wheel is 2.5". I'm sorry about the blurry photo, but the outside diameter of the lip on the hub cap center is also 2.5".
I haven't measured the internal diameter of the wheel opening in a while and I don't remember what it is, but it's an unusual number because I have a whole shelf full of center caps from different salvage yard cars that didn't fit.
3d printed and painted. They have a low polygon count by design that you can't see in that picture(lots of flat surfaces that make up the round part) I left it that way on purpose because I wanted it to look 3d printed.
That looks awesome. Seems like that's the best design solution, making them so they slide in from the back with a flange to hold them in place.
Yeah, thats how centerline did it. On yours, instead of plastic tabs to fit in the groove to lock it in, it could be done with a O-ring so you'd have no plastic fingers to break off.
It looks like my center caps will not fit your wheels. My OD is: 2.325" and the step (that fits into the wheel opening) is: 1.810". Good luck finding a solution.
Some kind of a spacer if the lip in the wheel is too small for the cap. But then silicone yes. Probably something like Permatex black. Make sure its centered while it dries if you cant find or make a spacer.
I'm thinking about using some spring steel, like the tines of a leaf rake, and epoxying five or six on the inside of the cap to make homemade clips. I'll let you know how it goes.
I'm thinking about using some spring steel, like the tines of a leaf rake, and epoxying five or six on the inside of the cap to make homemade clips. I'll let you know how it goes.
In case anyone cares, here's my old school measured drawing of the GTZ cap:
As I told jmbishop, it's been about 30 years since I did any drafting but I think you get the idea. jmbishop suggested 3D printing an adapter that replicates the bottom of the GTZ cap but will fit into the hupcap center. I think that's a great idea, but I will see if I can find some PVC pipe that's the right diameter.
Still working on the model but I've got it pretty close to being printable. The only measurement missing was the ID of the cap but that shouldn't be critical.
[This message has been edited by jmbishop (edited 05-26-2015).]
I made a pleasant discovery in the PVC aisle at the hardware store.
The male end has a flare that fits perfectly into the wheel. I'll have to trim the end of it, because the Fiero hub has a ring that fits right up into the wheel opening. Sorry for blurry photos.
So the plan is to trim the back side of the tapered male end, then cut down the female end and epoxy it to the inside of the hub cap center. If it works, the hub cap center will then just thread onto the spacer after it's inserted from the back of the wheel.
I should point out this is the rear wheel I'm working on. I haven't had a chance to see if the PVC piece will fit over the bearing cap on the front wheel. Based on eyeballing it last night I think it will, but I'll have to take the wheel off to make sure. Probably won't get a chance to do that until tomorrow.
Oh, and here's the measurement of the inside diameter of the GTZ cap. On the inside of the teeth, it's 1.975". The inside diameter of the cap itself is a bit narrower, 1.970".
[This message has been edited by Quad Raider (edited 05-27-2015).]
Progress. I had to use the Dremel to trim the inside of the male end to clear the bearing cap on the front hub. I also cut down the female end and epoxied it inside the cap. I am thrilled at the result. Sorry for the blurry photos.
It will be interesting to see how the PVC holds up to the heat generated by the brakes.
I have so much work to do to get the car on the road (finish engine rebuild, finish engine mounts, reinstall interior, paint car, build exhaust system, etc.), but at least I got my wheel caps figured out.
