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Discussion Starter #1
Made it to the track finally. Second time there. Last time I broke an axle so switched to SRA from the IRS.

Trouble is I cant 60' at all. Running Drag radials wondered what people are doing as far as setup goes to hook. Best was 2.08 ran 11.23 @136 know it would be deep in the 10s if could get it to hook up.

Right now it is a 9" moser rear end with adjustable uppers and lowers strange adjustable shocks stock fox body springs with a coil cut. Stock front suspension. weight was 3505

T56 with 3.73 in the rear end. I need more seat time shifting and launching still don't have a 2 step. It would bog down at 2500 launches and blow tires away at 3000. Was always super hot though air temp was 89 degrees.
 

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Discussion Starter #4
2.66 first gear

Nitto nto5r 275/40r17. Tried tire pressure from 15-20 tried heating them up in box and going around box best was when around 18 and heated them up pretty good. Think need to ride clutch a bit more. Just ran out of time.
 

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2.66 first gear

Nitto nto5r 275/40r17. Tried tire pressure from 15-20 tried heating them up in box and going around box best was when around 18 and heated them up pretty good. Think need to ride clutch a bit more. Just ran out of time.
There's your problem. Like mentioned, get a good bias ply tire. Try Hoosier or Mickey Thompson. Also, make sure your pinion angle is adjusted correctly.

Get some strange fronts and loosen them up to help transfer some weight. Set those rears loose too.
 

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I've never been a fan of the nitto's for strip use, but that's personal preference. I've found them to be a better street tire than a track tire. You may try a lower pressure to get a harder bite, but like mentioned above, until you get weight transfer down, only then can you worry about how you get them planted on the right set of shoes.
 

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You have a very low first gear and rear gear combo. I would go with a 26x10 stiff sidewall mickey thomspon. Any taller and you are hurting your starting line ratio even more. As you can't change the 1st gear in the transmission I would recommend a steeper rear end gear. For comparison I run a 3.41 first gear with a 4.56 rear and a 28 tall tire. 1.3X 60 foots all day long.
 

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Discussion Starter #8
Was afraid of that. I almost went with 4.10 in the rearend. Brand new rear end. was for strip/ street but its at the horsepower were I need to decide what I want to do with it. I will have to look into another set of tires for the track. Went with the drag radials for the street just was hoping could get them to work a bit better than they are.

Thank you
 

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You have enough clutch to make your radials work. The key will be in accepting that a radial needs to dead hook to be effective, which means your clutch will need to slip for a little over 16' (about 0.7 sec) in order to keep rpm above 4000 thru the launch. Your RXT can easily handle that, and you don't need more gear ratio to make it work- but you will need some sort of clutch slip controller to extend the slipping farther down the track. Some have been successful at modulating the clutch with their foot, but that takes a lot of trial/error practice to get any kind of consistency. It's much easier to precisely add slip time by using something mechanical, here's a list/links to devices specifically designed to extend clutch slip time...
Tilton Flow Control Valve
ClutchMasters Flow Control Valve
Magnus Launch control device
ClutchTamer Clutch Slip Controller

The ClutchTamer is my personal favorite as I designed it, but it's also the only one on the list that works with a cable clutch.

Grant
 

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Discussion Starter #12
Going to look into these tomorrow never have heard of them before but seems interesting. And working with stock clutch cable would be ideal. Thank you.
 

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So to be realistic...a Clutch Tamer will activate every time you push the clutch pedal in to upshift? So based on your calculation it would slip .7 on the launch and .7 on the 1-2, 2-3 & 3-4 shifts; .7 every time??? That’s 4 x .7 = 2.8 seconds? Is my math right? Even if the car accelerates quicker due to less bogging or spinning the tires, isn’t this murderous on the friction surfaces of the clutch, pressure plate and flywheel? I’ve had street clutches that I’ve played with on the strip and by feathering the clutch I’ve wasted one in a short night of racing. Seems like the same principle.
 

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I do like the concept of that Magnus Clutch Controller if you have a hydraulic clutch as it can be programmed to activate in as few or as many gear changes you want.
 

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So to be realistic...a Clutch Tamer will activate every time you push the clutch pedal in to upshift? So based on your calculation it would slip .7 on the launch and .7 on the 1-2, 2-3 & 3-4 shifts; .7 every time??? That’s 4 x .7 = 2.8 seconds? Is my math right? Even if the car accelerates quicker due to less bogging or spinning the tires, isn’t this murderous on the friction surfaces of the clutch, pressure plate and flywheel? I’ve had street clutches that I’ve played with on the strip and by feathering the clutch I’ve wasted one in a short night of racing. Seems like the same principle.
My calculation was about how long something needs to slip during launch, just so happens that some controlled slipping can improve power production during the shifts as well. Some clutches can't handle it, but the OP's RXT can. An important thing to remember is that it wastes a lot more power slipping the tires for 0.7 seconds than it does to slip a clutch for the same period of time. Same goes for any brief wheelspin that might occur after a shift. It's more efficient to briefly store the energy you are making during the shift, then feed that energy back in at a rate that does not cause the tires to spin. As a side benefit the controlled slipping after the shift also improves recovery rpm.

Here's something to think about- Ford says a $6500 factory sealed Coyote crate makes [email protected] / [email protected], the CS guys run at around 3175lbs. Current class records are 10.075 / 131.86. According to the calculators it should take around 583-614fwhp to post those numbers, but these are sealed NA 5 liter engines running a spec tune and spec gas. Rather than allowing the clutch to pull engine rpm all the way down as far as gear ratios might suggest, they use controlled clutch slipping to raise the lower parts of the rpm trace, which raises the rate of power production. They are basically taking the "negative" of being required to run a heavy 10" min diaphragm clutch, and turning that into a "positive" by exploiting it's ability to handle some controlled slipping to increase net power production.

Grant
 

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So to be realistic...a Clutch Tamer will activate every time you push the clutch pedal in to upshift? So based on your calculation it would slip .7 on the launch and .7 on the 1-2, 2-3 & 3-4 shifts; .7 every time??? That’s 4 x .7 = 2.8 seconds? Is my math right? Even if the car accelerates quicker due to less bogging or spinning the tires, isn’t this murderous on the friction surfaces of the clutch, pressure plate and flywheel? I’ve had street clutches that I’ve played with on the strip and by feathering the clutch I’ve wasted one in a short night of racing. Seems like the same principle.
Yep, every time. You of course want a disc that can handle slipping. I went overkill and bought a Clutch Dynamics twin ceramic disc late last year after going through two blue-printed king cobras from ProMotion Performance in two years and only getting a few good passes on them. Before the ClutchTamer the twin disc clutch would grab so hard the engine would bog horribly and now I can tune the slip and go quicker. I've made at least 30 passes this year.
 
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