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 Post Posted: Mon Feb 01, 2010 4:00 pm 
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The few times I had the roadster out last year, I noticed the 60' on it were inconsistent. Split times were great. Everyone says it's not spinning and I dont feel it spinning so I am gonna continue looking. I did, however, find a possible culprit(s). My wishbone "slider" was rusted horribly. I took it out and finally freed it up and cleaned it up. While I was under there I noticed that when the car was on the lift, I could NOT spin the rear tires at all. It was because the rear end was hanging due to the fact the lift is lifting on the chassis and since it was hanging, it put the weight of the rear end on the driveshaft loop. I hope this makes sense so far. The driveshaft was in a bind on the loop. I jacked up the rear end until the chassis came off the lift a little and noticed I could then spin the tires, but it wasnt easy. There was enough relief on the loop to allow it to turn. I assume when I am in the car, there is enough clearance. Otherwise it would have rattled my teeth I am sure. Anyway, I dont think I can lower the loop enough because I think it would end up hitting the top of the wishbone. I thought about moving the upper shock mounts up to the next hole to see if that would provide enough clearance. However, isn't that gonna change my 4 link setup??? I could move all locations up to the next hole I guess, but I wanted to check on here first to see what you all thought. In no way, do I want to change the 4 link setup at all because it leaves and drives too good now. I'm just trying to get some consistency down low. Any input?

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 Post Posted: Mon Feb 01, 2010 4:35 pm 
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If the driveshaft doesn't have a worn spot around it where the loop would touch it, that shouldn't be your problem. The froze-up wishbone could be a problem. Are you staging exactly the same every pass?

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 Post Posted: Mon Feb 01, 2010 4:55 pm 
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yeah, pretty close. we're talking about .05 in 60 feet though so it should be pretty obvious.

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 Post Posted: Wed Feb 03, 2010 8:29 am 
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so with the rear jacked up and suspension on full droop does the driveshaft foul the loop or does the prop joint bind ?

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 Post Posted: Sat Feb 06, 2010 10:13 am 
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With the jack under the rear end, there is MINIMAL clearance between the loop and the driveshaft.
With the jack under the frame and jacked up high enough to get the rearend off the ground, the driveshaft is pushed so hard against the loop (from the force of the coilovers) that you cant spin the wheels at all.
that make sense? I'll try to get some pics.

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 Post Posted: Sat Feb 06, 2010 11:17 am 
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You may have a little more clearance than you think. When you had the car raised up on the lift and jacked the rear suspension up just enough to lift the rear of the frame off the lift you probably still didn't have the suspension compressed nearly as much as you would have with the car on the ground. I would assume that the position of the arms supporting the front half of the car were behind the front axle centerline and therefore taking quite a bit of the balanced weight off of the rear suspension. The best way to check for actual clearance would be to use a drive on type rack and measure the ride height of the car and then jack up the chassis until the driveshaft touches and measure ride height again. Then you know how much travel it takes to cause an interference problem. I would modify the loop anyway but just wanted to point out that this isn't likely to be causing a problem while racing the car.

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 Post Posted: Sat Feb 06, 2010 8:07 pm 
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okay. that makes a lot more sense. You are right about the front lift arms being behind the front axle centerline. I didnt think about it taking weight off the back end as well. I knew I never felt any problems. I just knew when I picked it up with the lift, I couldnt spin the back wheels which got all this concern started. Thanks for the clarification. Obviously, I will check it once I get it all put back together. I was just trying to address the issue while I have it in pieces and up on the lift. Thanks again.

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