C4 Frame Project

[Custer55]

Do you know the overall tire width in front? I'm surprised a 275 works. I could go further inside towad the frame but not outside. So with more offset i could go bigger than 245. The taller 55 fenderwell opening helps.

I was surprised that everything clears too. I just put my old wheels and tires on thinking it would just give me a better idea how wide a wheel would work. At the bottom of the tires it measures 68 3/4" wide. I would guess it should be less at the top of the tire with the camber in the front end. Should gain about a 1/4" or so per degree of camber.
FYI my frame rails measured 4 3/8" off the ground just behind the kick up. The fender openings are 23 3/4" from the ground. Slightly smaller tires would be better, even though I have not had any rubs so far, to gain a bit better margin for error.
Brian

[chevynut]

Usually around 68" and you start getting rubbing problems when you turn sharply and the suspension is compressed. However, with the large SAI of the late C4 the tire moves fore and aft a lot when you steer, and the rack limits turning radius a little. I don't think you'd get anywhere near a 275 up front with a stock suspension and steering, even at the same outside tire width.

[Custer55]

Steering Column Update

Just a quick update. I made a new tilt lever for my modified van column to match the turn signal lever. It is just a 55 turn signal lever and knob trimmed shorter and 1/4" x 28 fine threads cut on the end to replace the van tilt lever with the rubber knob.



This looks much better than the van lever and knob (below)



Brian

[markm]

I did the same thing my aftermarket column in 55 came with ugly billet crap.

[WagonWonder]

Just a quick update. I made a new tilt lever for my modified van column to match the turn signal lever. It is just a 55 turn signal lever and knob trimmed shorter and 1/4" x 28 fine threads cut on the end to replace the van tilt lever with the rubber knob.


Brian

Pretty cool

[Custer55]

New Tires and Wheels

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I got my new tires mounted and balanced on the Corvette wheels this weekend.
They are Nitto 555 NT tires. 285/40/17 on the rear. 255/40/17 on the front. I had 2 of the wheels refurbished through Keystone Automotive ($150. a piece with tax) and the other 2 I just sanded out the clear coat and gave them a couple fresh coats of clear.


All cleaned up and ready to go on the car.


You can tell the difference in size and the wheel I re-cleared and the refurbished wheel. Hopefully not so noticeable on the car and after a few months of use.




Bolted on and ready for a test drive, but that will have to wait until next weekend if the weather is nice again next weekend. (There is a chance of rain snow mix mid week.) It sits about 3/8" lower in front due to the smaller tire on the front and slightly higher in back so I may adjust the rear ride height with the spring bolts. I would not put any bigger tire than the 285 on the rear as they were a challenge to get them on the car. I had to unbolt the rear shocks to let the wheels drop a bit more to get them on the car. I may have to see if I can lower the rear shock mounts to avoid that in the future. The drivers side had just enough room (still the original quarter panel) but the passenger side I had to let the air out of the tire and then I was just able to force it past the wheel opening. The lower quarter panel was replaced a few years after I bought the car back in the 70's so I think the wheel opening is a bit lower on that side. I still need to get center caps for the wheels also. I only have 3 and there not in very good shape so I may have to check out Ebay. My wife will be happy now as she will get her wheels and tires I borrowed back on her Corvette.

[chevynut]

Looks great Custer55. Who is this "Keystone" company you're referring to? I was thinking I'd like to have my truck wheels refurbished. The clearcoat sux.....you put a wheel weight on the wheel, it chips the clearcoat, and corrosion starts. I wish they WEREN'T clearcoated.

I still don't know how you ever ran a 275 tire on the front of your car. I have a customer's frame in the shop right now that has 275s on 9.5" C4 wheels with 50mm offset on a late suspension. At full lock, the tires are barely clearing the frame....like by 1/16" but that's at full shock extension (~2-2.5" droop). I know you said you had 56mm offset wheels which would make it worse. Our frame rails are parallel at 34 3/4" width at the point the tires touch the frame. Maybe at ride height there is more clearance but I don't know for sure how much. Also, the outside of the tires is at about 68.75" which is really wide, way too wide for a dropped car imo. 12mm less would be 68.28" which is where yours theoretically should be. I'm curious if your tires would rub the fender if you removed the front spring, went to full lock, and pushed the suspension up to max compression travel. I suspect they would.

Some day I plan to remove the front spring of my 56 parts car and see if I can figure out where the limit is on tire width by putting spacers between the wheel and hub and running through full suspension travel at full lock......if I ever have time.

This is looking down on the driver's side tire at full lock.

20170323_001.JPG

[BamaNomad]

The refurbished 90 Corvette wheels look great on your '55!~ I've considered using them on my car as well, but the ones I have are from a ZR-1 and the 11" width on the rear wheels is too wide for the car and chassis. I'm a bit surprised that the 9.5" wheels work for your fronts... I haven't decided on a size yet, but for myself and my use, I'd rather use a 7" or 7.5" wide wheel without issues than a wider one that scrubs at times. I think they made the 90 Corvette wheels in 8.5" width as well as the 9.5" and the 11" ZR1 size. If the 9.5 wide wheel works for you, that may encourage me to look for a set of 8.5's..

[Custer55]

Looks great Custer55. Who is this "Keystone" company you're referring to? I was thinking I'd like to have my truck wheels refurbished. The clearcoat sux.....you put a wheel weight on the wheel, it chips the clearcoat, and corrosion starts. I wish they WEREN'T clearcoated.

I still don't know how you ever ran a 275 tire on the front of your car. I have a customer's frame in the shop right now that has 275s on 9.5" C4 wheels with 50mm offset on a late suspension. At full lock, the tires are barely clearing the frame....like by 1/16" but that's at full shock extension (~2-2.5" droop). I know you said you had 56mm offset wheels which would make it worse. Our frame rails are parallel at 34 3/4" width at the point the tires touch the frame. Maybe at ride height there is more clearance but I don't know for sure how much. Also, the outside of the tires is at about 68.75" which is really wide, way too wide for a dropped car imo. 12mm less would be 68.28" which is where yours theoretically should be. I'm curious if your tires would rub the fender if you removed the front spring, went to full lock, and pushed the suspension up to max compression travel. I suspect they would.

Some day I plan to remove the front spring of my 56 parts car and see if I can figure out where the limit is on tire width by putting spacers between the wheel and hub and running through full suspension travel at full lock......if I ever have time.

This is looking down on the driver's side tire at full lock.

[ATTACH]7041[/ATTACH]

Thanks! Keystone Automotive is a body shop parts and materials supplier. They have locations all over the place http://www.lkqcorp.com/en-us/locationResults. They sell mostly to body shops, but they do sell to anyone at the Stevens Point, WI location. A friend of mine runs a business in the same building as them so I am able to get his discount when I buy stuff from them. If you search the internet there are other places to get wheels re-done but you have to send them to them by ups or fedex so it was easier for me to just do it locally.
I was surprised to that the 275's didn't rub anywhere. I never crawled under the car to see just how close so mine may have been about the same as yours. My frame width is the same as a stock 55 Chevy frame at the point where the tire is closest to the frame at full lock. I think there may be a little better clearance at ride height than at full droop or full compression. The clearance at full lock is a bit better now with the 255's on the front (maybe an extra 1/4" of clearance). I'm not sure what would happen at full lock and full compression but I don't think that will happen very often if at all driving the car. Probably the only time that may happen is going into a steep driveway opening to fast, so it's fairly easy to avoid that.
Brian

[Custer55]

The refurbished 90 Corvette wheels look great on your '55!~ I've considered using them on my car as well, but the ones I have are from a ZR-1 and the 11" width on the rear wheels is too wide for the car and chassis. I'm a bit surprised that the 9.5" wheels work for your fronts... I haven't decided on a size yet, but for myself and my use, I'd rather use a 7" or 7.5" wide wheel without issues than a wider one that scrubs at times. I think they made the 90 Corvette wheels in 8.5" width as well as the 9.5" and the 11" ZR1 size. If the 9.5 wide wheel works for you, that may encourage me to look for a set of 8.5's..

Thanks,
I'm pretty sure 11" wheels would be to wide on the back unless you narrow the rear end and widen the wheel tubs. Probably a 10" wheel would be the limit on the back. I'm not sure about 8.5" wheels for a 90 Vette but I think the C5 and up, and maybe later C4's came with 8.5" wheels on the front. When I eventually buy different wheels I will probably go with 9" up front and 10" in the back. The front width you want to use depends on the tire size you are going to use also. If you have a tire size in mind just get a wheel that is the best width for that tire and then figure out what offset will put the outside of the tire where you want it. Always better to have a bit to much offset though as you can use a spacer to move the wheel out a bit if you need to. I have 3/16" spacers on my rear wheels, which centers them in the tub pretty well.
Brian

[WagonWonder]

I know I'm knew here but it seems to me that concern over "full lock" as described above would only be very rare, momentary and under some severe circumstances which most likely would results in, near or during a wreck. I understand the desire to know but just can't vision myself and my wagon getting in that shape and hope I never do.

[chevynut]

I know I'm knew here but it seems to me that concern over "full lock" as described above would only be very rare, momentary and under some severe circumstances which most likely would results in, near or during a wreck. I understand the desire to know but just can't vision myself and my wagon getting in that shape and hope I never do.

Yes it's probably rare unless you drive aggressively as in an autocross. Also keep in mind that some of the C4 racks are only 1.96 turns lock to lock, so about 1 turn center to lock. It may happen more with a C4 setup than a tri5 stock steering that you have to crank and crank to get to lock.

The thing is for me is, I don't EVER want the tire to be able to touch the fender, even if it may be a "rare" occurrence.

[chevynut]

I've considered using them on my car as well, but the ones I have are from a ZR-1 and the 11" width on the rear wheels is too wide for the car and chassis.

It depends on offset and whether you have minitubs or not. An 11" wheel with a 295 tire should work if you have minitubs. If not, a 275 or possibly a 285 is about the limit. You would need a minimum of about +60mm offset for them to work with a 295 tire on a late rear suspension. It would be really tight. Unfortunately, all the C4 ZR-1 11" wheels had 36mm offset. The GS 11" wheels had 56mm offset which might work depending on actual fenderwell width.

If the 9.5 wide wheel works for you, that may encourage me to look for a set of 8.5's..

I have 8.5" wheels with +50mm offset and 245 tires on the front of my Nomad with a late suspension. No rubbing problems inside or outside.

[BamaNomad]

That's great information CN... that 8.5" wheels with 50mm offset and 245 tires 'work' without rubbing or interference. I assume you are referring to a standard Corvette 17" wheel of a specific year?? Or?

I like the 90 Corvette wheels utilized by Custer55 but I was a bit surprised that 9.5" would work on the front. For my 57, I lean towards a simple appearing 5-spoke wheel (preferably GM design). I had hoped to use the C5 magnesium wheels, but the ones I tried would not work with my chassis. I don't need HUGE, max width tires. I just want it to handle well, brake well, and of course look good too.. but I'm not going for a 'hotrod/racer' look or function for maximum traction. I think 8.5" is probably the largest I would want to go for the rear, and a 7 or 7.5" wheel would suit me just fine on the front. You seem to have a wealth of information on wheel fitment with the stock-width C4 suspension under Trifive bodies, and I learn something every time you post info on that! I still don't have enough knowledge/information to choose a wheel that is going to suit me; so I will probably wait until I sit the body on the chassis and do some measurement as to 'inner wheel clearance', and outer wheel clearance from the wheel mount point. I also would prefer to be able to mount/dismount a wheel/tire without issues (loosening lower shock mount, etc).

PS. Obviously it's difficult to make any absolute or even near absolute statements when tubs and modified frames/suspensions are involved, as each situation would/could be unique...

[Custer55]

That's great information CN... that 8.5" wheels with 50mm offset and 245 tires 'work' without rubbing or interference. I assume you are referring to a standard Corvette 17" wheel of a specific year?? Or?

I like the 90 Corvette wheels utilized by Custer55 but I was a bit surprised that 9.5" would work on the front. For my 57, I lean towards a simple appearing 5-spoke wheel (preferably GM design). I had hoped to use the C5 magnesium wheels, but the ones I tried would not work with my chassis. I don't need HUGE, max width tires. I just want it to handle well, brake well, and of course look good too.. but I'm not going for a 'hotrod/racer' look or function for maximum traction. I think 8.5" is probably the largest I would want to go for the rear, and a 7 or 7.5" wheel would suit me just fine on the front. You seem to have a wealth of information on wheel fitment with the stock-width C4 suspension under Trifive bodies, and I learn something every time you post info on that! I still don't have enough knowledge/information to choose a wheel that is going to suit me; so I will probably wait until I sit the body on the chassis and do some measurement as to 'inner wheel clearance', and outer wheel clearance from the wheel mount point. I also would prefer to be able to mount/dismount a wheel/tire without issues (loosening lower shock mount, etc).

PS. Obviously it's difficult to make any absolute or even near absolute statements when tubs and modified frames/suspensions are involved, as each situation would/could be unique...

Bama, I don't think you would have the mount/dismount issues I do with a 57. The wheel opening on a 55 is lower than a 56 or 57. If you look back in my build I originally used 95 Trans Am wheels and tires. 16 x 8 wheels with 55 mm offset (6 3/4" back space). Those were a good starting point to see what would fit. To me those were to narrow and didn't fill the wheel wells enough for my taste. And on the back they were harder to get on and off because of the smaller rim dia. and taller tire side wall (245/50/16). The front and rear tire calculator on this site is a great tool also. I have used it many times!!

Brian