relocating batwing mounts over 1 inch
Thread Starter
Intermediate
Joined: Aug 2016
Posts: 36
Likes: 3
relocating batwing mounts over 1 inch
first of all i cant edit the heading but is 1/2 over , i hate to see anything obviously out of sync , and looking at the rear of my c4 i'm automatically drawn to the fact the passenger side tire is 1/2 inch further inset than the drivers side which is flush to fender with the current wheel setup i have , i want to know as anyone addressed this issue , i hear its common , i have measured everything and the problem lies in the mount for the bat wing. It looks like i could drop the bat wing and redrill the mounts over a 1/4 inch or get serious and replace the attachments points all together , but i don't want to go that in depth
, any ideas or solutions done in the past would be helpful , and this is with 9.5 inch z06 c5 replica wheel . thanks.. also since im planning the mods to install 17x11 oem ZR1 wheels i feel this needs to remedied before starting the big doggie mods .
, any ideas or solutions done in the past would be helpful , and this is with 9.5 inch z06 c5 replica wheel . thanks.. also since im planning the mods to install 17x11 oem ZR1 wheels i feel this needs to remedied before starting the big doggie mods .
Last edited by ervinc; Nov 20, 2017 at 07:35 PM.
Safety Car
Joined: Aug 2013
Posts: 4,429
Likes: 605
From: Minneapolis Mn
what he said.If it was mine, I'd jack it up and support the rear on jackstands and take off the wheels. I'd then start measuring everything on it and see if it's actually out of whack or something else.
Another option would be to pay a frame shop to go over it. They should have the equipment and measurements to confirm if it's correct or not.
Another thought might be the car could have been hit in the past and a not-the-best repair was done and the body panel might be misaligned vs the original position.
Le Mans Master
Joined: Aug 2015
Posts: 6,118
Likes: 1,994
From: St. Charles MO
Assuming it's not a problem with wheel offset (see replies above), it's probably aligned properly with the front subframe, and you're just seeing the body that didn't line up properly. The quality control on C4 body panel measurements and alignments leaves something to be desired, but I think the frames and subframes are usually fine. Check with diagonal measurements from front to rear subframe reference points. If they are equal, then leave it alone. If you move the rear batwing to one side, you'll end up with significant thrust misalignment. If it's just the body panels, you can try to get a body specialist to line them up carefully for you.
Safety Car
Joined: Aug 2009
Posts: 3,752
Likes: 276
From: Melbourne, Victoria, Australia
first of all i cant edit the heading but is 1/2 over , i hate to see anything obviously out of sync , and looking at the rear of my c4 i'm automatically drawn to the fact the passenger side tire is 1/2 inch further inset than the drivers side which is flush to fender with the current wheel setup i have , i want to know as anyone addressed this issue , i hear its common , i have measured everything and the problem lies in the mount for the bat wing. It looks like i could drop the bat wing and redrill the mounts over a 1/4 inch or get serious and replace the attachments points all together , but i don't want to go that in depth , any ideas or solutions done in the past would be helpful , and this is with 9.5 inch z06 c5 replica wheel . thanks.. also since im planning the mods to install 17x11 oem ZR1 wheels i feel this needs to remedied before starting the big doggie mods .
, any ideas or solutions done in the past would be helpful , and this is with 9.5 inch z06 c5 replica wheel . thanks.. also since im planning the mods to install 17x11 oem ZR1 wheels i feel this needs to remedied before starting the big doggie mods .First check your rear wheel camber, the offset bolt / washer camber adjustment can move. If one wheel has negative and the other positive camber it can look wrong.
Use a piece of string with a heavy washer and hold to top side of the tire, and see if the camber is ok by gap between top and bottom of tire.
Usually the trailing arms (dog bones) are bent or the bushes are bad, the easy to bend them. just as easy to fix one that is slightly bent.
Racer
Joined: Aug 2016
Posts: 354
Likes: 54
This is very common on the C4 vettes. Assuming the frame is true and square (which I will bet it is), the bodytub was not perfectly aligned with the frame causing the fenders to not set true to the tires from side to side.
You will have big issues if you start trying to move the batwing relative to the frame, as the rear wheels will no longer be true to the location of the front wheels.
Unfortunately, without removing the rear bodytub from the glued mounting to the rest of the body and relocating, there really is no practical solution.
You will have big issues if you start trying to move the batwing relative to the frame, as the rear wheels will no longer be true to the location of the front wheels.
Unfortunately, without removing the rear bodytub from the glued mounting to the rest of the body and relocating, there really is no practical solution.
Melting Slicks
Joined: Mar 2016
Posts: 2,778
Likes: 580
From: Langley BC
first of all i cant edit the heading but is 1/2 over , i hate to see anything obviously out of sync , and looking at the rear of my c4 i'm automatically drawn to the fact the passenger side tire is 1/2 inch further inset than the drivers side which is flush to fender with the current wheel setup i have , i want to know as anyone addressed this issue , i hear its common , i have measured everything and the problem lies in the mount for the bat wing. It looks like i could drop the bat wing and redrill the mounts over a 1/4 inch or get serious and replace the attachments points all together , but i don't want to go that in depth , any ideas or solutions done in the past would be helpful , and this is with 9.5 inch z06 c5 replica wheel . thanks.. also since im planning the mods to install 17x11 oem ZR1 wheels i feel this needs to remedied before starting the big doggie mods .
, any ideas or solutions done in the past would be helpful , and this is with 9.5 inch z06 c5 replica wheel . thanks.. also since im planning the mods to install 17x11 oem ZR1 wheels i feel this needs to remedied before starting the big doggie mods .In my opinion, moving the batwing mounts is going to be a big project since you will likely have to modify a bunch of stuff to make it work... more trouble than its worth.
Proabbly the best bet would be to just use a 1/2 hub-cebtric wheel spacer on the side that is further inboard to even things up.
Also I don't know if you noticed this but the front wheels (on my C4 stock) stuck out more than either rear ones. That bugged me too...
Last edited by DMITTZ; Nov 25, 2017 at 12:48 AM.
Race Director
Joined: Dec 2002
Posts: 13,348
Likes: 233
From: SCMR Rat Pack'r Charter Member..Great Bend KS
Yep. ^ Providing the camber is correct on both rear wheels, and the wheels are correct, the easiest, cheapest, quickest, best way to correct this is a 1/2" wheel spacer.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Le Mans Master
Joined: Aug 2015
Posts: 6,118
Likes: 1,994
From: St. Charles MO
I wouldn't even recommend a wheel spacer, except maybe for car shows where appearance matters more than function. If you space just one wheel out, you've still jacked up certain aspects of suspension geometry. It would be worse on the front, where you'd introduce asymmetric steering geometry and probably create a pull. But it's also not ideal for the rear.
Again, unless you can actually verify that the subframes themselves are out of square with one another, just accept that it's the body work being misaligned and/or see if a Corvette body expert can address the misalignment.
Again, unless you can actually verify that the subframes themselves are out of square with one another, just accept that it's the body work being misaligned and/or see if a Corvette body expert can address the misalignment.
Thread Starter
Intermediate
Joined: Aug 2016
Posts: 36
Likes: 3
i believe its figured out, i spoke to prior owner, he according to his memory sometime back he had a bad bearing in the rear hub passenger assy , so he got a good deal on a complete hub assy and replace it on the passenger side , he thinks it was from a 87 corvette, which may explain why the 17x11 zr1 wheels were even with passenger side fender but stuck out on drivers side, this is leading me to believe if i can find a 87 rear hub assy for the drivers side i may be able to use my ZR1 wheels and avoid all the machine work for the big doggie mods . wheels are equal in width , all alignments has been checked , all checked good , no drift or pull , just cosmetic. I'll try and locate a 86-87 spindle assy and realign it and see what happens . so much just because i dont like the look of it.. i need to get it figured out or learn to accept it so i can get ready and have it painted this winter.
Last edited by ervinc; Nov 26, 2017 at 11:31 PM.
Le Mans Master
Joined: Aug 2015
Posts: 6,118
Likes: 1,994
From: St. Charles MO
Sorry to burst your bubble, but Autozone and Rockauto both show the same exact rear bearing/hub for a 1986 and a 1996 Corvette: AC Delco 513013. So that's not the issue...unless it's coming apart. I doubt it is, but double check it anyway.
Thread Starter
Intermediate
Joined: Aug 2016
Posts: 36
Likes: 3
the difference isnt the hub bearing but the spindle assy itself, if you look up the article on how to do the big doggie mod, i think it would make more sense, it looks like the early 84-87 spindle assy is narrower than the 88-96 , the plan was to do the big doggie mod and machine work to the newer assy to decrease the width, but if in fact the prior owner used an early spindle assy , half the work is done, at least thats how it appears to me... id rather see im wrong before i spend the money , but it appears thats the issue im having .
Le Mans Master
Joined: Aug 2015
Posts: 6,118
Likes: 1,994
From: St. Charles MO
the difference isnt the hub bearing but the spindle assy itself, if you look up the article on how to do the big doggie mod, i think it would make more sense, it looks like the early 84-87 spindle assy is narrower than the 88-96 , the plan was to do the big doggie mod and machine work to the newer assy to decrease the width, but if in fact the prior owner used an early spindle assy , half the work is done, at least thats how it appears to me... id rather see im wrong before i spend the money , but it appears thats the issue im having .
As for the "big doggie" mod, I don't really see the point. You can just get 11" or 11.5" wheels with the proper offset and run 315s on the back of your stock C4. You can also run them up front. Why swap spindles and machine parts?
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
Check the casting information on the knuckle on your car. I don't believe that what you believe is possible. I don't believe the caliper bracket will bolt directly to the early knuckle allowing the use of later caliper etc.
Here's casting information and location on the later knuckle.
https://www.ebay.com/itm/C4-Corvette...FaD1Vc&vxp=mtr
Early casting likely 14084094 or something very different than what's in the eBay offering.
Here's casting information and location on the later knuckle.
https://www.ebay.com/itm/C4-Corvette...FaD1Vc&vxp=mtr
Early casting likely 14084094 or something very different than what's in the eBay offering.
Thread Starter
Intermediate
Joined: Aug 2016
Posts: 36
Likes: 3
Oh, I didn't realize you meant the spindle was also changed out. That's...ummm...an interesting way to repair a bad wheel bearing!
As for the "big doggie" mod, I don't really see the point. You can just get 11" or 11.5" wheels with the proper offset and run 315s on the back of your stock C4. You can also run them up front. Why swap spindles and machine parts?
As for the "big doggie" mod, I don't really see the point. You can just get 11" or 11.5" wheels with the proper offset and run 315s on the back of your stock C4. You can also run them up front. Why swap spindles and machine parts?
the big doggie mod comes into play to run the oem zr1 wheel, the common 5 spoke replica is available in the offset to run on later c4, but if you really like the 17x11 1991 zr1 wheel which isn't available aftermarket , then you either do the mod or hang the grand sport flares
Thread Starter
Intermediate
Joined: Aug 2016
Posts: 36
Likes: 3
Check the casting information on the knuckle on your car. I don't believe that what you believe is possible. I don't believe the caliper bracket will bolt directly to the early knuckle allowing the use of later caliper etc.
Here's casting information and location on the later knuckle.
https://www.ebay.com/itm/C4-Corvette...FaD1Vc&vxp=mtr
Early casting likely 14084094 or something very different than what's in the eBay offering.
Here's casting information and location on the later knuckle.
https://www.ebay.com/itm/C4-Corvette...FaD1Vc&vxp=mtr
Early casting likely 14084094 or something very different than what's in the eBay offering.
thanks for the insight ,
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
If this car were here we'd use a Tram gage from maybe the lower front ball joint fitting to the differential in an X to check actual placement. There wouldn't be a need to do a visit to a collision shop.
What's tolerable to assume it's correctly orientated? No idea but if it were substantially different then you look much further.
Right BJ fitting to left camber bracket or maybe cover left lower bolt and then - left BJ fitting to the right camber bracket or maybe the right lower cover bolt. With the tram gage you could do the X from multiple points.
You haven't mentioned how or what you're measuring but I'm guessing tire sidewall to lip. That doesn't get it! 1/2" sounds like an approximation - I really like Metric dimensions and no approximations.
If you were to want to measure to the body edges I believe you need to use straight edges on maybe the rotor surface. I'd think it easier to set camber to 0 but that would depend upon familiarity of measuring and the devices used.
What's tolerable to assume it's correctly orientated? No idea but if it were substantially different then you look much further.
Right BJ fitting to left camber bracket or maybe cover left lower bolt and then - left BJ fitting to the right camber bracket or maybe the right lower cover bolt. With the tram gage you could do the X from multiple points.
You haven't mentioned how or what you're measuring but I'm guessing tire sidewall to lip. That doesn't get it! 1/2" sounds like an approximation - I really like Metric dimensions and no approximations.
If you were to want to measure to the body edges I believe you need to use straight edges on maybe the rotor surface. I'd think it easier to set camber to 0 but that would depend upon familiarity of measuring and the devices used.
Last edited by WVZR-1; Nov 27, 2017 at 11:07 AM.
Thread Starter
Intermediate
Joined: Aug 2016
Posts: 36
Likes: 3
If this car were here we'd use a Tram gage from maybe the lower front ball joint fitting to the differential in an X to check actual placement. There wouldn't be a need to do a visit to a collision shop.
What's tolerable to assume it's correctly orientated? No idea but if it were substantially different then you look much further.
Right BJ fitting to left camber bracket or maybe cover left lower bolt and then - left BJ fitting to the right camber bracket or maybe the right lower cover bolt. With the tram gage you could do the X from multiple points.
You haven't mentioned how or what you're measuring but I'm guessing tire sidewall to lip. That doesn't get it! 1/2" sounds like an approximation - I really like Metric dimensions and no approximations.
https://www.corvetteforum.com/forums...4-c4-base.html
look at post #9 , that was with 36mm zr1 wheels
If you were to want to measure to the body edges I believe you need to use straight edges on maybe the rotor surface. I'd think it easier to set camber to 0 but that would depend upon familiarity of measuring and the devices used.
What's tolerable to assume it's correctly orientated? No idea but if it were substantially different then you look much further.
Right BJ fitting to left camber bracket or maybe cover left lower bolt and then - left BJ fitting to the right camber bracket or maybe the right lower cover bolt. With the tram gage you could do the X from multiple points.
You haven't mentioned how or what you're measuring but I'm guessing tire sidewall to lip. That doesn't get it! 1/2" sounds like an approximation - I really like Metric dimensions and no approximations.
https://www.corvetteforum.com/forums...4-c4-base.html
look at post #9 , that was with 36mm zr1 wheels
If you were to want to measure to the body edges I believe you need to use straight edges on maybe the rotor surface. I'd think it easier to set camber to 0 but that would depend upon familiarity of measuring and the devices used.
thanks for the input
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
Back to the op's original idea about moving the batwing a 1/2" toward one direction. Don't forget that the motor to the rearend is one piece due to the c-beam. They are not mounted separately like a 70's Camaro. The motor mounts are mounted to the frame and the batwing mounts also mounted to the frame. There is no "play" in between unless you are talking about torqueing the rubber motor mounts and bending the c-beam.
Thread Starter
Intermediate
Joined: Aug 2016
Posts: 36
Likes: 3
Back to the op's original idea about moving the batwing a 1/2" toward one direction. Don't forget that the motor to the rearend is one piece due to the c-beam. They are not mounted separately like a 70's Camaro. The motor mounts are mounted to the frame and the batwing mounts also mounted to the frame. There is no "play" in between unless you are talking about torqueing the rubber motor mounts and bending the c-beam.