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KjcfeF100
(@kjcfef100)
Eminent Member

Hey guys, it takes me forever to find time to do posts, I don't know how some people seem to post multiple times daily on various forums......I set up a suspension camera to try to learn more about how my suspension is acting. Both of these videos are of the same pass, my new best 11.14 E.T., with a 1.570 60 foot time. This was first pass of the day with probably the coolest clutch temperature of the day. The suspension cam is good quality, but the side shot is not very good, but may be of some use. Looking to see if anyone has any good advice or comments on what you can see suspension related here?

Suspension cam: https://www.youtube.com/watch?v=_seMrEDqRmg
Side cam: https://www.youtube.com/watch?v=oOa_E-bcbrk

[Adjustment details: Launch was not at my intended 4600 RPM, but was at 5100 (best 60' of the day was a 1.544 that was from a 6350 RPM launch by mistake). Rear shocks (single adjustment Calvert) set at max 9, slicks at 13 psi, Caltrac Bars set at 1/4 turn preload, front shocks are some old Competition Engineering 3 way adjustable set at 90/10 IIRC. Clutch slip on launch was .91 sec. before full lock-up. Clutch set at 430 lbs base, and 9.5 grams per lever.]

Here's a graph of the launch:

A few more gee-wiz details from that same day back in October:
I had 3 passes that day in the 120 mph range. The air temp started out around 58* and may have risen to about 62* as a high. (Most of my E.T. gain from a best previous 11.59 ET was in the back half 1/8 mile where it dropped .248 sec., vs dropping .202 sec. in the 1/8 mile.) Traction was not great, I had to pedal it a little on 2 of 4 passes, and completely aborted a 3rd pass due to getting too loose for my comfort. It still managed the 11.14, a 11.41, and a 11.29.

Keith

Keith
[Img">https://i.postimg.cc/JzgH9dK1/Sig-Photo-3.jpg[/Img">

Quote
Posted : 20/03/2019 8:24 pm
Battlestar
(@battlestar)
Famed Member

One note, no tire spin at all. You need to get some rotation. That is why it's taking .9 to get clutch lock up.

It's biting too hard, so you need to loosen things up in the back, and tighten the front. Which hole is the bar in? I found that the old 90/10 shocks I used to run were too loose for my car. I needed to control the front end rise better.

I did hear the tires(on suspension video) just kinda chirp as the clutch engaged. I think that is when the front end dropped and unloaded the rear. That is where controlling how fast the front end rises makes a big difference.

I can't see how it would loose traction, unless the surface is that bad down track? Are you powershifting it? Sounds like you may be lifting on the gas? Too much unloading can upset the chassis and cause issues.

Just some quick thoughts.

Larry
1964 Galaxie wagon
**2006 NORTH Q/S POINTS CHAMP**
**2009 NORTH Q/S POINTS CHAMP**

Canton Automotive Machine
Carls Ford Parts
Hyatt Racing Clutch

Larry
1964 Galaxie wagon
**2006 NORTH Q/S POINTS CHAMP**
**2009 NORTH Q/S POINTS CHAMP**
Canton Automotive Machine
Carls Ford Parts
Hyatt Racing Clutch

ReplyQuote
Posted : 21/03/2019 6:55 am
nolaf65
(@nolaf65)
Eminent Member

I would put new shocks on front first stop bouncing down the track .Then it may spin the slicks enough to get to it to sixty foot your not power shifting lot et loss there.Bouncing is causing bad handling down track.

ReplyQuote
Posted : 21/03/2019 10:29 am
KjcfeF100
(@kjcfef100)
Eminent Member

Each time I go to the strip, the tire spin and clutch lock-up is different on my first pass vs each pass thereafter. I've assumed it was due to more heat in the clutch disc as the day goes on, but this day there was more down time between passes, so I don't know the cause. I posted video and graph of this first pass of the day since it was my best E.T. to date; however the next 3 passes were somewhat different regarding spin and lockup.

quote:


no tire spin at all. You need to get some rotation. That is why it's taking .9 to get clutch lock up.....Are you powershifting it? Sounds like you may be lifting on the gas?


Larry, you're correct on that pass, no tire spin. The next 3 passes had more spin and the clutch accordingly locked up in .16, .25, and .13 seconds. Ideally I'd like to have 1-2 revolutions and .4 to .7 seconds of clutch slip, but I haven't found that adjustment yet. Even with more tire spin the best 60 ft that day wasn't much better (1.544)..... Power-shifting it? No and yes. Video and my graph shows on that pass I must have been blipping the throttle, but that's not by design; I must be subconsciously doing it. I seem to blip the throttle on the first pass some days, and once I see it on the graph, I remind myself to keep the throttle matted...... The front Caltrac bar is in the lower hole.......As far as loosing traction down track, I doubt it was great track prep (VHT) that day, but most cars (and a lot much quicker than mine) were getting down the track fairly well that day. It's a good surface, fairly recently repaved, and they hold a NHRA Lucas Oil divisional race there once a year. (Silver Dollar Motorsport Park)

nolaf65

quote:


I would put new shocks on front first stop bouncing down the track


I'm sure that's good advice, I've been working on and changing one thing at a time, so I can try to determine results. They are fairly old and low cost front shocks, and I'm sure a quality double adjustable and some more experimenting and/or knowledge of what to do will help.

Keith

Keith
[Img">https://i.postimg.cc/JzgH9dK1/Sig-Photo-3.jpg[/Img">

ReplyQuote
Posted : 21/03/2019 9:26 pm
Battlestar
(@battlestar)
Famed Member

I'd guess most "faster cars" were all automatics, maybe even Glides that only shift once. You pounding 5 gears gives the truck more chance to break loose on a gear change. That along with the chassis bobbing up/down some.

I typically on my first pass make sure I get some heat in the clutch either while driving to lanes(if I know I'm not sitting long), or while in lanes I give it some ride time. Just short loads with line lok set. A few times is usually good enough. If I don't, mine will tend to slip more the first pass out. Especially if it is on the edge and I haven't put 1/4 turn in it lately. Every few races it tends to wear just enough to get soft in high gear change. Putting 1/4 turn brings it back.

With your minimal seat time and erratic track prep it is going to be tough to get things ironed out quickly. Though, if you try to manage things tightly, be very repetitive on your actions, it will come easier.

I think controlling the front end rise/fall will again help with your 60ft. I know it did mine. That chassis video really shows how the tires squeal as it tries to break loose after the front end drops. I've survived with SA shocks up front, though wished I'd bought DA.

Larry
1964 Galaxie wagon
**2006 NORTH Q/S POINTS CHAMP**
**2009 NORTH Q/S POINTS CHAMP**

Canton Automotive Machine
Carls Ford Parts
Hyatt Racing Clutch

Larry
1964 Galaxie wagon
**2006 NORTH Q/S POINTS CHAMP**
**2009 NORTH Q/S POINTS CHAMP**
Canton Automotive Machine
Carls Ford Parts
Hyatt Racing Clutch

ReplyQuote
Posted : 22/03/2019 10:09 am
sr530
(@sr530)
Estimable Member

I gotta disagree on that pass with regards to tire spin. The graph shows the tires started spinning at about .25, and the clutch is all but locked up by .46. The clutch does get bounced loose again at .62 and .75 or so, but the tires didn't actually dead hook until about 1.0 sec in.

That big spike at the beginning of the DS and clutch traces shows there's about .10 sec of wrap in your rear suspension/sidewalls. A more effective rear shock angle should improve that.

Grant

[IMG">http://grannys.tripod.com/logo53png.png[/IMG">[URL="http://clutchtamer.com"">[IMG">http://grannys.tripod.com/logo5png.png[/IMG">[/URL">[IMG">http://grannys.tripod.com/logo52png.png[/IMG">

ReplyQuote
Posted : 22/03/2019 10:41 am
KjcfeF100
(@kjcfef100)
Eminent Member

quote:


I gotta disagree on that pass with regards to tire spin. The graph shows the tires started spinning at about .25


Well, yes, technically the Drive Shaft graph does show that slight evidence of a little spin, but it's certainly not much; slowing down the video speed I can't pick it up with my eyes at all. I should have perhaps said "very minimal tire spin, (and not at the initial hit)" on that particular run. As I mentioned before, the next 3 passes went into far more noticeable spin right at the initial hit.

For example, run #4 launch:

Keith

Keith
[Img">https://i.postimg.cc/JzgH9dK1/Sig-Photo-3.jpg[/Img">

ReplyQuote
Posted : 22/03/2019 9:56 pm
Battlestar
(@battlestar)
Famed Member

My guess is that erratic tire spinning/clutch slipping is the front end unloading the chassis. Slowing the front end rise should help that.

Just so I'm guessing right. The RED is engine rpm, the BLACK is input shaft, the BLUE is driveshaft.

Larry
1964 Galaxie wagon
**2006 NORTH Q/S POINTS CHAMP**
**2009 NORTH Q/S POINTS CHAMP**

Canton Automotive Machine
Carls Ford Parts
Hyatt Racing Clutch

Larry
1964 Galaxie wagon
**2006 NORTH Q/S POINTS CHAMP**
**2009 NORTH Q/S POINTS CHAMP**
Canton Automotive Machine
Carls Ford Parts
Hyatt Racing Clutch

ReplyQuote
Posted : 25/03/2019 9:23 am
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