Help on wheel conversion please

[Chop Top]

Our trucks are 5x5 wheel patterns on (I believe) a 5/8th" stud.

Passenger cars like Camaros, SS Impalas, etc are 5x4.5 or 5x4.75 on a 7/16th" stud.

Here's the deal. The wheels I want are only available in a 5x4.5. I haven't built the narrowed rear end yet, so I can build it to whatever specs I need the axles to be. It is the FRONT that I need help with.

I have to buy all new rotors and disc brakes, calipers, etc. anyway. I know that the 67-72 C10 guys have a trick that they use to convert their front rotors to 4.5 or 4.75 by either swapping a van rotor in it or buy sending it off to get redrilled. Is there enough room to redrill a 4.5 pattern on a 5x5 hub closing in on the center like that ?

I talked to Wilwood and they felt confident there were no safety issues dropping the FSC down to a 5x4.5 pattern, and I can just order the kit to the new specs for the back. The front I have to get crafty. The only problem he commented on might be the center hub and its fitment over the center bearing cap.

There is a guy on the C10 forum that sent his rotors off to Moser Engineering to have them filled and rebuilt. Has anyone done this or thought of doing it ? It's just the front wheels that are the issue. This is for a 1993 C/K single cab BTW for those who don't know.

[someotherguy]

GMT400 trucks run a 14mm stud...you don't get a 5/8" stud until you get into the 3500HD (meaning straight axle, 19.5 10 lug wheel, 15,000 lb GVWR 3500HD).

The Impala SS is 5x5 just like a truck. And anything modern, you're not looking at stud sizes in inches, but in mm - 12 for the small stuff, 14 for the trucks.

I haven't seen anybody convert a fullsize GM truck of any year to 5x4.75* or 5x4.5. Not saying it hasn't been done, but I sure haven't seen it. The 71-72 trucks are 5x5 already so less incentive to bother converting as they were no longer 6x5.5 anyway.

I say, hop down to the parts store and make a bolt circle template from a rear drum with a 5x4.5 pattern. Then try laying it on top of a 5x5 front rotor and see if there's any way in hell that small of a bolt circle fits around the hub with room for any meat left between the hub and the stud holes. The hub is fairly large on our trucks (2WD, anyway) because of the old school inboard/outboard bearing arrangement, vs. the all inboard (sealed) style of the GMT800-newer.

Richard

*I seem to recall on some 68 and older trucks guys might be using Chevelle (or other mid-size GM) rotors, don't know what they're doing to adapt them to the trucks, to convert to disc brake and 5 lug - that's 4.75, of course.

[Chop Top]

That's a good idea. The center hub specs on a FSC assembly is listed as being 78.1.

[randeez]

78mm seems a little large = just a hair over 3", so if you're going with a 4.5 center- so you'll have only 3/4" of clearance from the hub to center of the stud so even less to the edge

now that i think about it s/o/g is right the hub it quite large

[Chop Top]

What about adapters ? The shortest I could find were 1.5" thick. With the BellTech spindles pushing the wheel furthur out already, if I run a 6 inch front wheel and a 1.5 wheels adapter/spacer I wonder what the outcome would be ?

6 inch fronts is a **little** more prostreet than I was going for, but I saw those on a truck and it doesn't really look that bad when you get a nice street tire on it.

[Buddies'Garage]

Most machine shops will be able to re-drill the bolt pattern. I suggest taking a new rotor & explaining what you want. They should be able to price the job once they know what is involved. I have converted numerous vehicles to different bolt patterns. IMO adapters will be fine on the front. They start @ 1" thickness increasing to as much as 2.5" depending on your needs. I prefer re-drilling b/c the maximum front space is obtained & I like a deeper wheel over a high offset wheel when it comes to appearance.

[Buddies'Garage]

If you're using different width wheels you won't be rotating anyway. Why not machine the front wheels for 5x5" fitment? Unless they're open lug that might be simpler.

[1998454]

I have 5-4.5 to 4.75 adapters from jegs that are 1" thick. They are on a show car that is only driven 1k miles per year at most, and the wheels are only 3.5" wide. If it were a daily driver i would throw the adapters in the trash!
What about adapters ? The shortest I could find were 1.5" thick. With the BellTech spindles pushing the wheel furthur out already, if I run a 6 inch front wheel and a 1.5 wheels adapter/spacer I wonder what the outcome would be ?

6 inch fronts is a **little** more prostreet than I was going for, but I saw those on a truck and it doesn't really look that bad when you get a nice street tire on it.

[1998454]

The wheels he wants aren't available in 5x5
If you're using different width wheels you won't be rotating anyway. Why not machine the front wheels for 5x5" fitment? Unless they're open lug that might be simpler.

[Chop Top]

I'm afraid the diameter of the inner portion of the FSC rotor doesn't allow enough clearance to squeeze down to a 4.5 bolt pattern. Does anyone have disassembled pics or an exploded diagram for reference ?

The inner diameter of the wheel I am mounting on the front hub has been confirmed at 80.5mm or 3.17”.

[someotherguy]

Brother...sure sounds like time to pick some different wheels. :D

Richard

[randeez]

Brother...sure sounds like time to pick some different wheels. :D

Richard

this :lol:

but you've done what you've wanted to with your truck up till now why stop now - if i have a few minutes during lunch i'll try n whip ya something up realy quick while i have autocad open- it'll be crude.... and 2d, but you'll have a visual (given dimensions you've given are correct)

[Chop Top]

That is awesome. I'll let you in on why I'm pushing the issue this hard.

Mickey Thompson just put all their HR1 and HR 2 riims in overstock. A $1500 wheel sells for 200 bucks INCLUDING free shipping. But they only have a 4.5 set.

This guy did it so why can't I ?

http://forum.73-87chevytrucks.com/smforum/index.php?topic=16958.0

All you yahoos don't go running to M/T to buy out the overstock now, ya hear ???

[randeez]

it doesnt look to bad... pm your email i'll send this pdf of the dwg to you

[randeez]

sent.. and i forgot to show what the 14mm on 4.5 would give you for clearance

[someotherguy]

Mickey Thompson just put all their HR1 and HR 2 riims in overstock. A $1500 wheel sells for 200 bucks INCLUDING free shipping. But they only have a 4.5 set.

This guy did it so why can't I ?
I don't see anywhere in that thread where he talks about the bolt pattern on his wheels.

I did see this: "The truck was built by Art Morrison Enterprise to show case there products."

I would be willing to bet that it doesn't have stock front suspension, possibly some kind of car suspension grafted on, Mustang II rack & pinion maybe?

Richard

[Chop Top]

You're right, probably a Mustang II setup. I was mainly referring to the 6 inchers up in front and how they don't look that bad with the right tires on them.

[nlkicker05]

Not an obs but my cousin did the conversion to 5x4.75 on his nbs, heres a pic.
http://i77.photobucket.com/albums/j46/nlkicker05/38821_408319043836_547888836_4609946_2785386_n.jpg

[nlkicker05]

A closer shot of the front wheel not the best pic but here it is.
I can try to get more specs if needed.
http://i77.photobucket.com/albums/j46/nlkicker05/jjturbomotor.jpg

[Chop Top]

That's your cousin ? Doesn't he post LS1 trucks a lot ? I have been BEGGING that guy for outside tread to tread measurements for his back wheels/tires and axle specs. He emailed me back once last year but neve got back to me. Hook me up dude.

[nlkicker05]

That's your cousin ? Doesn't he post LS1 trucks a lot ? I have been BEGGING that guy for outside tread to tread measurements for his back wheels/tires and axle specs. He emailed me back once last year but neve got back to me. Hook me up dude.
Yea he is my cousin, I don't think he has been posting much on forums for a while now. What exactly do you need? I'll try to get as much info as i can, off the back of my head, i know the axles are moser.

[Chop Top]

1. Axle flange to Axle flange measurement
2. size/width of wheels
3. Backspacing for said wheels.
4. tread to tread width as it sits for the rear tires