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Nice thing about the VB&P Dual mount rear spring, it gives you a perfect mounting point for wheelie bars. I will be removing the angle brackets I made, trim them and powdercoat. Fabrication is done.
No offense but I don't think I would hang those off the spring mounts like that. There's allot of leverage on those bars. If the car actually needs them a good hit might twist the mounts. They are only bolted on. JMO.
No offense but I don't think I would hang those off the spring mounts like that. There's allot of leverage on those bars. If the car actually needs them a good hit might twist the mounts. They are only bolted on. JMO.
Tom
They are 1/4" I beam construction through bolted to the crewmember with 2 3/8" grade 8 bolts with a 1/4" mounting plate bolted to it with 2 3/8" grade 8 bolts They are way beefier than the mounts that the upper and lower wheelie bar rods are bolted to. The 5/16 bolt holding the upper rod to the mount would definitely shear off before those mounts ever thought of bending. The shocks are functional on the bars also. No problem.
Are you having wheelie problems? I seem to remember your build, but don’t remember it having that kind of power. No offense, beautiful car and build.
I have drag radials, 535 hp + 175 shot , 6 speed, 4.11 on a prepped track it will get up, it is really light. I lose steering launching with street tires and no nitrous. I like the look also.
I see some destortion in that mono spring, changing direction twice. The red bracket appears to be the culprit putting undo stress on the spring. Is that normal?
They are 1/4" I beam construction through bolted to the crewmember with 2 3/8" grade 8 bolts with a 1/4" mounting plate bolted to it with 2 3/8" grade 8 bolts They are way beefier than the mounts that the upper and lower wheelie bar rods are bolted to. The 5/16 bolt holding the upper rod to the mount would definitely shear off before those mounts ever thought of bending. The shocks are functional on the bars also. No problem.
OK. I have a dual mount rear spring as well and it just looked precarious to me.
I see some destortion in that mono spring, changing direction twice. The red bracket appears to be the culprit putting undo stress on the spring. Is that normal?
I see some destortion in that mono spring, changing direction twice. The red bracket appears to be the culprit putting undo stress on the spring. Is that normal?
This is coming from a structural engineer and someone who relies on wheelie bars on every pass at the track. (see photo below) The way you have the wheelie bars mounted is a recipe for disaster for the following reasons. The brackets you are mounting to are really only designed for up and downward forces that are imposed on it from the spring. You side mounted a bracket and a 4' long wheelie bar to it that is going to apply a high amount of rotational forces to the same bracket. If you end up hitting the wheelie bars hard I would not want to be in the lane next to you as if you have a failure you will end up tearing off your rear spring and mounts. Do not underestimate the forces that the wheelie bars place on the attachment points. If you look closely at my wheelie bar leaf you will see that there is so much load on it that it is in the shape of an S.
Take this how you will, I am just trying to help you avoid being one those unforgettable drag racing youtube parts breakage videos.
This is coming from a structural engineer and someone who relies on wheelie bars on every pass at the track. (see photo below) The way you have the wheelie bars mounted is a recipe for disaster for the following reasons. The brackets you are mounting to are really only designed for up and downward forces that are imposed on it from the spring. You side mounted a bracket and a 4' long wheelie bar to it that is going to apply a high amount of rotational forces to the same bracket. If you end up hitting the wheelie bars hard I would not want to be in the lane next to you as if you have a failure you will end up tearing off your rear spring and mounts. Do not underestimate the forces that the wheelie bars place on the attachment points. If you look closely at my wheelie bar leaf you will see that there is so much load on it that it is in the shape of an S.
Take this how you will, I am just trying to help you avoid being one those unforgettable drag racing youtube parts breakage videos.
I don't believe this is an issue at all. The brackets are 1/4" I beams sandwiched on the frame/differential crossmember through bolted through the frame crossmember with 4 3/8 grade 8 bolts. The pressure is up top right by the frame crossmember attachment point and there is a full 1/2" of steel there both at the bracket and above at the crossmember attaching point which is 1/2" on both sides. All my hardware is 3/8" Grade 8 bolts. There is no way this is bending. Look at it again, picture 2 specifically, I could lift my car off the ground with 1 of these easily, the load is distributed on both sides, crossmember is bolted to the frame on both sides and the differential is also a structural member from the upper mounts to the pinion bracket bolted to the frame, 3 attachment points. It is stronger than a 2 1/2"" weld from the bracket to the axle housing as designed. I am understanding the rotational forces I just don't see how anything there can bend. The 5/16 grade 5 hardware on these Competition Engineering wheelie bars would fail way before anything else.
I see there's a lot of work in the install...but the fact that everything is going to hit those two 7/16" sombrero mounting bolts that are already trying to hold the rear in place makes me have some concern. They aren't in real thick metal themselves.
I added a "wing" off my sombrero mount that extends to that welded crossmember just to the rear. I have bolts attaching the wing to the welded one. I figured it was sitting there doing nothing and could be used to support the rear under a hard launch. Not sure if it helps, but nothing has moved back there in years.
That would be the weakest point in the car but way stronger than the bars and bar hardware. The differential also bolts to the middle of that crossmember and attaches to the frame at the pinion mount so it is supported on both sides of the spring mount. Can you send me a photo of the wings you are talking about? I am also going to have to make halfshaft loops. Maybe I can incorporate an additional support when I put them in. I could also link the differential crossmember to the frame crossmember with an angle and 2 u channels. Might be over thinking it.
This is what Jim is talking about. I added this stiffener plate on my frame when i restored my 66. Also in the second photo toward the top right rear there is a plate that connects the frame rail to the top of the hat mounting pad. You can really only do that plate if the frame is off the car.
Last edited by 4 Speed Dave; Jan 29, 2018 at 11:18 AM.
Reason: added photo
I was using a Poly mount on the front and it cut a hole through the frame mount like a hole punch. But I was running 9's and pulling wheelies the day before I found it and I never felt anything...I think the rear mount was stabilizing things. I built a stronger front mount too.
JIM
Last edited by 427Hotrod; Jan 29, 2018 at 02:33 PM.
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63Mako IRS Wheelie bars mounted
I have a dual mount rear spring as well and it just looked precarious to me. 
