Chassis guys step in

DRR Top Comp

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quote:
Originally posted by DLR:
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Originally posted by Mike Rietow:
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Originally posted by DLR:
Interesting topic here, brings me to an age old issue I have always had with my car. Similar to Brian's car, it's a 5.50 SBC chassis car, 4 link strut deal with anti roll. Problem is when track conditions are good the car leaves straight with short wheelies of about 50 feet. But when traction starts to diminish, car drifts to the left while front tires are in the air. I've squared, I've added neg. preload to no avail. Maybe I need to add a little rear steer IDK.
LF601
RF559
LR668
RR611
I've seen other door cars do this also, what's your thoughts?

Negative preload is for high hp cars 1100 1200 hp up. Low hp like you have, rearend rotation controls chassis dynamics. I could fix it in a flash, although it would be a process of elimination, meaning it could be a few different things causing this phenomenon.

I suspect when the left side rear damper gets warm, it develops hysteresis (slack). Pull them both off. If they're gas emulsion, when you shove the shaft into the main body it'll come back out on it's own. If one does and the other doesn't it'll be obvious the problem (gas leaked out). If there not gas emulsion you can't do any kind of rudimentary test yourself like this besides cycling both listening for air in oil, but you could just switch the driver side damper to the other side. Try it like that, might be a easy fix.

I did that a couple weeks ago when I had them off to see if I could feel anything. I swapped side to side and saw no change. BTW these are Afco Big gun shocks.
Keep in mind this problem only arises when starting line conditions go south.

Afco big gun have a gas bladder, they're gas emulsion. Last set I had here one had leaked the gas out, one shaft returned on it's own to fully extended when compressed, the other didn't.

Did you pull the springs off yours and check this, when you switched them side to side?

Could be the damper going away, not the track. I heard people say the track went away a lot, and I never noticed any differences in the track.

The gas is there to backup the oil.

Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018

Ignored post by Mike Rietow posted

DRR Top Comp

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A damper that repeats rearranges the energy created through the suspension into heat in the oil, the same every round.

I had one guy who crushed 4 $400 oil pans doing rear bumper ripping wheel stands on his third pass, every time he went to the track. He thought it was happening because the track was coming around, when the sun went down.

I bolted a set of real dampers on the back of this car and he was able ramp the nitrous progressor to 100% a half second sooner after TB release. Never wheel stood again.

Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018

Ignored post by Mike Rietow posted

DLR

DRR Sportsman

posted

actually I removed the springs...lol. I can't ever remember any gas return when compressed, not even when new. part number 3850BG

Posts: 469 | Location: BENTON HARBOR, MI | Registered: August 29, 2007

Ignored post by DLR posted

DRR Top Comp

posted

quote:
Originally posted by DLR:
actually I removed the springs...lol. I can't ever remember any gas return when compressed, not even when new. part number 3850BG

I'd call em and say hey, are these BG's I have, supposed to be gas emulsion? The gas must've leaked out before I got em.

The set I had here were new as well. One like I said, was good. The shaft returned to fully extended when compressed. That's how you do a rudimentary test on a gas emulsion damper, to see if the gas has leaked out.

Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018

Ignored post by Mike Rietow posted

DLR

DRR Sportsman

posted

I can tell you one thing, the difference in bump and rebound setting are night and day. Rebound from loose to tight are extreme. However the compression settings almost change nothing, or very little when bench testing. I even went so far to go to the hot rod store and get a new set off the shelve. They were the same feel on compression.
By the way, I don't recall new shocks tied together to keep them compressed.????

Posts: 469 | Location: BENTON HARBOR, MI | Registered: August 29, 2007

Ignored post by DLR posted

DRR Top Comp

posted

quote:
Originally posted by DLR:
I can tell you one thing, the difference in bump and rebound setting are night and day. Rebound from loose to tight are extreme. However the compression settings almost change nothing, or very little when bench testing. I even went so far to go to the hot rod store and get a new set off the shelve. They were the same feel on compression.
By the way, I don't recall new shocks tied together to keep them compressed.????

I'm definitely not trying to tell you what you have, I'm trying to help you to figure out what you have!!

If it's a gas emulsion, like the BG's I've had here, I'd want the gas in em, if I were you. Maybe there's a BG option not gas emulsion, I dunno. I'd find out if I were you though. That would be my suggestion. If I were you I'd be searching that part #.

I think you could find some good use for some digressive valving on rebound as well, the BG's I had here, were as you've described on the bench. But that's just BG valving.

Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018

Ignored post by Mike Rietow posted

DRR Top Comp

posted

Gas emulsion is a bonus selling point, it's a higher end damper. If all the other BG part numbers mention they're gas emulsion, and your part# doesn't, that's a real strong indicator yours are not gas emulsion. Then I'd verify it with Afco Monday morning. That would be my suggestion.

Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018

Ignored post by Mike Rietow posted

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DLR, this is the only part # I could for a BG gas emulsion damper.

Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018

Ignored post by Mike Rietow posted