VBP leaf spring
Melting Slicks
Joined: Feb 2001
Posts: 3,330
Likes: 13
From: Europe , Luxembourg
I made my own traction bar out of a solid motor mount in front, a mounting bracket I fab'ed in the back, and a double-Heim bar in between. Nothing else was changed. Now I have absolutely NO wheel hop. The twisting force on the diff is transferred directly to the cross member by the traction bar to the solid motor mount on the cross member. The adjustable length bar allowed me to preloaded the traction bar.
I'm sold on traction bars for years with rubber or poly batwing mounts instead the solid disk on previous years. I just would not buy the monster bar sold by VBP and others. Besides, they didn't make it for the spring mounts with 3 bolts instead of the earlier 4 bolts. You can make your own for less $$ and with more clearance.
[/QUOTE]
This traction bar is useless as it moves with the rear end instead of being fixed to the car chassis.
Rgds. Günther
I'm sold on traction bars for years with rubber or poly batwing mounts instead the solid disk on previous years. I just would not buy the monster bar sold by VBP and others. Besides, they didn't make it for the spring mounts with 3 bolts instead of the earlier 4 bolts. You can make your own for less $$ and with more clearance.
[/QUOTE]This traction bar is useless as it moves with the rear end instead of being fixed to the car chassis.
Rgds. Günther
Melting Slicks
Joined: Aug 2004
Posts: 2,063
Likes: 1
From: Beverly Massachusetts
I made my own traction bar out of a solid motor mount in front, a mounting bracket I fab'ed in the back, and a double-Heim bar in between. Nothing else was changed. Now I have absolutely NO wheel hop. The twisting force on the diff is transferred directly to the cross member by the traction bar to the solid motor mount on the cross member. The adjustable length bar allowed me to preloaded the traction bar.
I'm sold on traction bars for years with rubber or poly batwing mounts instead the solid disk on previous years. I just would not buy the monster bar sold by VBP and others. Besides, they didn't make it for the spring mounts with 3 bolts instead of the earlier 4 bolts. You can make your own for less $$ and with more clearance.
I'm sold on traction bars for years with rubber or poly batwing mounts instead the solid disk on previous years. I just would not buy the monster bar sold by VBP and others. Besides, they didn't make it for the spring mounts with 3 bolts instead of the earlier 4 bolts. You can make your own for less $$ and with more clearance.
I was thinking the same thing and looking at his picture it looks like what he has is totally useless because its just a bar that is connected from the back of the diff to the nose of his diff which isnt doing anything. I would say that if you are getting that much twist on your diff that is mounted to the frame then i would check the rubber mount that is at the nose of the diff and maybe replace it with a poly mount to stiffen it up. traction bars are used to eleminate axle wrap which shouldnt be that much of a factor with the corvette rear end. again i would have to say that excessive wheel hop is caused by the wrong spring and shock combo.
Last edited by LIQUIDDRAGON; Nov 6, 2009 at 08:21 PM.
Drifting
Joined: Sep 2006
Posts: 1,986
Likes: 21
From: Columbus MN
Theorize all you want, but it works. Period.
Last edited by MN80Vette; Nov 6, 2009 at 05:00 PM.
Burning Brakes
Joined: Mar 2004
Posts: 816
Likes: 1
From: Finland
Do you mean that since you preload the bar by extending it as long as possible the motor mounts left edge in the picture is pushed against the fixed cross member and that prevents rear ends rear cover area from bending down wards? But upwards this does not limit the movement...which could be good as well. So may opinion is thet if you weld the motor month 3-4 inched to the left and get a 3-4 inch longer bar then it would be better.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
I'm having a heck of time with vbp fiberglass springs. It's a 360lb spring. I looked under the car one day and noticed it was breaking apart. I ordered another one to replace it and talked with the someone at vbp about it. Never really got an answer on why it broke. Well here I am again with a broken spring. I'm leery to order another one. Does anyone else have this issue? Any ideas on what would do this? I would guess this spring doesn't have 20 miles on it in the last 5 years.
Lots of these springs break due to heat, a lot of them is due to improper mounting.
The TRW spring "must"be able to float in rubber,if you have it "locked" down that could be the reason you keep breaking springs.
I have a feeling the traction bar mount could be the problem.
Drifting
Joined: Sep 2006
Posts: 1,986
Likes: 21
From: Columbus MN
Do you mean that since you preload the bar by extending it as long as possible the motor mounts left edge in the picture is pushed against the fixed cross member and that prevents rear ends rear cover area from bending down wards? But upwards this does not limit the movement...which could be good as well. So may opinion is thet if you weld the motor month 3-4 inched to the left and get a 3-4 inch longer bar then it would be better.
Think of the plane of the bat wing. Forces of hard acceleration try to change the angle of that plane. The traction bar resists those forces by transfering those forces to the cross member.
Melting Slicks
Joined: Aug 2004
Posts: 2,063
Likes: 1
From: Beverly Massachusetts
It's hard to see in this picture, but the motor mounts is at about a 35 degree angle from horizontal. The bar transfers forward force from the bottom of the diff carrier (spring mount) to the motor mount. The motor mount cannot move forward because of the bolt at the top (under tension, not pressure) and the lower rear edge of the cross member.
Think of the plane of the bat wing. Forces of hard acceleration try to change the angle of that plane. The traction bar resists those forces by transfering those forces to the cross member.
Think of the plane of the bat wing. Forces of hard acceleration try to change the angle of that plane. The traction bar resists those forces by transfering those forces to the cross member.
Le Mans Master
Joined: Oct 2007
Posts: 7,451
Likes: 974
From: RI, Now Franklin/Nashville TN
Just as another reference, I have had my 360 spring from VBP on my car since 1985 with zero issues running KYB shocks, Bilstein HD's, and currently Bilstein Sports. I also have had both the OEM Y pipe and currently 2.5 Stainless steel true duals with no issues but I do have the OEM heat shield. If your springs are breaking, something else besides the spring is wrong, especially if it has happened more than once. I doubt it is the spring that is defective!
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Thread Starter
Instructor
Joined: Oct 2008
Posts: 154
Likes: 5
From: Colorado Springs
I tried to get some more pictures today but forgot my camera at home. The cell phone pictures didn't turn out. I was hoping to hear back from v&bp today but no luck. I'll let everybody know what they think the problem is. I'm still at a loss.
Thread Starter
Instructor
Joined: Oct 2008
Posts: 154
Likes: 5
From: Colorado Springs
I have been waiting for V&BP to get back to me. They said they would look at the pictures and get back to me. I have followed up once after and still no answers yet. Here are more pictures.
Thread Starter
Instructor
Joined: Oct 2008
Posts: 154
Likes: 5
From: Colorado Springs
I got a response back from VBP that was vague and referred to heat as the possible problem. I agree with you that something else possibly the traction bar is causing the problem. If it was heat the two stickers they have on the spring should show some sign of heat damage I would think. I'm going to call and talk to the tech that wrote me. I'll let you know where that goes.
Le Mans Master
Joined: Oct 2000
Posts: 6,362
Likes: 30
From: Oak Harbor WA
I'm thinking that traction bar has to be mounted with alot more torque then the standard spring pads and is causing stress cracks that eventually break. How much tq do you use when tightening the bolts?
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
If you still have the traction bar installed I would recommend a steel plate between the bottom of the diff housing and the lower spring plate (traction bar plate) so the rear bolts can be torqued against the plate instead of the spring.
Thread Starter
Instructor
Joined: Oct 2008
Posts: 154
Likes: 5
From: Colorado Springs
Well I'm finally getting around to replacing this. I don't really have any answers as to why its failed twice on me. I checked temps after a cruise and the spring was 125 degrees. My mufflers have a heat shield and the pipes are wrapped so I don't think its heat. V&BP didn't have any answers either. I'm going to get rid of the traction bar and see how that goes. I hate to get rid of it as it was great bottom out protection for the exhaust but I don't know what else it could be. Here's some pictures. Let me know if something jumps out at you.
Pro
Joined: Apr 2008
Posts: 596
Likes: 6
From: Irving Texas
WHOA......judging by the bad *** flowmaster exhaust setup and big meaty slicks.......I'd say the traction bar is doing it's thing right and the car squats super quick....thereby snapping the VBP bar. Notice the passenger side is damaged more than the drivers side.
I'm no expert but I'm willing to say the VBP guys aren't designing these things for bad *** launches. Alot of drag racers place an air bag on the passenger side to support this super squat.
I'm no expert but I'm willing to say the VBP guys aren't designing these things for bad *** launches. Alot of drag racers place an air bag on the passenger side to support this super squat.