drive shaft loop
- Thread starter xtweakerx
- Start date
Yeah, If I wasn't running late for work, i would have expanded and said something very similar. They usually fail at the connection point, and failing at the rear is not very dangerous for the driver or catapulting. But the front is dangerous for both...
Glad you were able to get confirmation from BMR. It's always good to get the confirmation from someone with more experience. I was using my general sense of physics and my information gathered from Myth Busters.
stangdude2000
Founding Member
Makes perfect sense now. Not sure why I was thinking of it breaking in the middle. Things almost always break at the joints first. I guess having the rear loop helps protect in the rare case of a break in the middle.
jwgroovin
New Member
Anyone having problems with the front BMR loop interfering with a Hurst shifter? Mine bangs against the loop from time to time and we're going to try to shim the mount area about 1/4" and see if that provides the clearance needed...
John
John
Actually, the Hurst helped. The stock shifter really mashed into it with 1st, 3rd, and 5th. With the Hurst it only happens in first. But yeah, TacoBill's solution was a spacer and it worked just fine (I believe it was 1/4"). He has the MGW and had the same issue. I'm going to make a spacer, I just haven't had time, and with the Hurst, it really hasn't been as much of an issue. I don't know if this issue is exclusive to BMR or not. From what I can tell, their loop is a bit larger around than most (which to me, is better so if there's any flex, it has plenty of clearance so it doesn't hit the spinning driveshaft)
Five Oh Brian
Member
The NHRA rules require a driveshaft loop within 6" of the front U-joint when your car is capable of 13.99 quarter mile times with slicks or 12.99 with street tires.
One of our local tracks requires a loop at 12.99 or quicker with slicks or drag radials, while our other local track is much more conservative and requires a loop at 13.99 or quicker for d/r's or slicks.
As already mentioned, the critical (and most common) failure is a front u-joint, hence the NHRA mandating that it be within 6" of the front u-joint. I my 1968 Pontiac GTO, due to a custom exhaust I had, I mounted a loop about 8-9" back and they always gave me grief at tech inspections, but would eventually give me warning and let me run.
A buddy of mine had a front u-joint failure in his '71 Mustang Vert (351 Cleveland, 4-speed, and NO loop) while driving down the road at about 40mph. It dented the floor pan badly, catapulted his car about a foot into the air (luckily he wasn't going around a corner!), and after the shaft bent back it snapped the rear u-joint, bounced out from under the car and smashed through the windshield of the car that was following him! Talk about a mess! It made me a believer in driveshaft loops instantly!
One of our local tracks requires a loop at 12.99 or quicker with slicks or drag radials, while our other local track is much more conservative and requires a loop at 13.99 or quicker for d/r's or slicks.
As already mentioned, the critical (and most common) failure is a front u-joint, hence the NHRA mandating that it be within 6" of the front u-joint. I my 1968 Pontiac GTO, due to a custom exhaust I had, I mounted a loop about 8-9" back and they always gave me grief at tech inspections, but would eventually give me warning and let me run.
A buddy of mine had a front u-joint failure in his '71 Mustang Vert (351 Cleveland, 4-speed, and NO loop) while driving down the road at about 40mph. It dented the floor pan badly, catapulted his car about a foot into the air (luckily he wasn't going around a corner!), and after the shaft bent back it snapped the rear u-joint, bounced out from under the car and smashed through the windshield of the car that was following him! Talk about a mess! It made me a believer in driveshaft loops instantly!
Casey4s
New Member
Nope, if you have two shafts (like stock) you have to have two loops.
I just now ordered the Granatelli front loop ($108 shipped) to go with my BMR rear loop.
I just now ordered the Granatelli front loop ($108 shipped) to go with my BMR rear loop.
