|
Re: Launch problems
[Re: JERICOGTX]
#2112331
07/18/16 11:08 AM
07/18/16 11:08 AM
|
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
68LAR
OP
master
|
OP
master
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
|
They are Hoosiers. So if I buy new slicks, should I go with MT's then, if the Hoosiers are too soft? If so, I don't see an exact match to the size I have now. I see a 29.5 X 10.5-15 with a stiff sidewall. I also see a 29.5 X 11.5 - 15 which would be within a 1/2" of what I have now. Which would you choose?
Last edited by 68LAR; 07/18/16 11:22 AM.
4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
|
|
|
Re: Launch problems
[Re: weedburner]
#2112398
07/18/16 01:13 PM
07/18/16 01:13 PM
|
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
68LAR
OP
master
|
OP
master
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
|
Your clutch hits the tires/chassis harder than they can currently handle.
When your engine loses rpm on launch, it's dumping stored inertia energy along side the torque the engine is making, creating an intense torque spike that will be gone as soon as rpm stabilizes (heavier flywheel just made it worse as it stores more energy). That rpm loss probably only lasts for .3 of a second or so, so to me optimizing the tires/shocks/chassis to counter that .3 second spike results in the tires/shocks/chassis being less than optimum for the rest of the run. If you reduce the hit of your clutch just enough to eliminate the rpm loss on launch, your tires/shocks/chassis can be optimized for the entire duration of 1st gear instead of just the first .3 seconds. No need for super stiff shocks if your clutch does not hit super hard.
The resulting launch will be softer, but it won't be slower. You can likely do this with the clutch & steel flywheel you currently have, just requires thinking outside the box. I hear what you are sayin', but the engine does not loose rpm at launch. When I leave out on the clutch the tires spin instantly. Sometimes the car will walk out with the spin, other times the car just sits there with the tires spinning... I'm seeing the light that I need a new set of slicks. I just have to decide what make and size to go with..
4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
|
|
|
Re: Launch problems
[Re: 68LAR]
#2112506
07/18/16 03:23 PM
07/18/16 03:23 PM
|
Joined: Oct 2014
Posts: 104
Washington
weedburner
member
|
member
Joined: Oct 2014
Posts: 104
Washington
|
I hear what you are sayin', but the engine does not loose rpm at launch. When I leave out on the clutch the tires spin instantly. Sometimes the car will walk out with the spin, other times the car just sits there with the tires spinning... I'm seeing the light that I need a new set of slicks. I just have to decide what make and size to go with..
You probably don't notice the loss. Do you log rpm? With no changes other than going from aluminum flywheel to heavier steel version, that indicates to me that a more intense torque spike on launch is what's knocking your tires loose. When you get the clutch to hit just right, you will be able to drop the slicks and step right up to radials.
Last edited by weedburner; 07/18/16 03:43 PM.
|
|
|
Re: Launch problems
[Re: 68LAR]
#2112571
07/18/16 05:03 PM
07/18/16 05:03 PM
|
Joined: Jan 2003
Posts: 10,038
MN
JERICOGTX
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 10,038
MN
|
They are Hoosiers. So if I buy new slicks, should I go with MT's then, if the Hoosiers are too soft? If so, I don't see an exact match to the size I have now. I see a 29.5 X 10.5-15 with a stiff sidewall. I also see a 29.5 X 11.5 - 15 which would be within a 1/2" of what I have now. Which would you choose? ALWAYS go with a stiff sidewall slick. For your car, I would go with a M/T 29.5x9 STICK tire. They are similar to a 10.5W tire, and have a stiffer sidewall.
69 GTX
68 Road Runner
|
|
|
Re: Launch problems
[Re: JERICOGTX]
#2112579
07/18/16 05:16 PM
07/18/16 05:16 PM
|
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
68LAR
OP
master
|
OP
master
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
|
They are Hoosiers. So if I buy new slicks, should I go with MT's then, if the Hoosiers are too soft? If so, I don't see an exact match to the size I have now. I see a 29.5 X 10.5-15 with a stiff sidewall. I also see a 29.5 X 11.5 - 15 which would be within a 1/2" of what I have now. Which would you choose? ALWAYS go with a stiff sidewall slick. For your car, I would go with a M/T 29.5x9 STICK tire. They are similar to a 10.5W tire, and have a stiffer sidewall. Not sure that going with a tire that will be 3" narrower than I run now would be the right choice? I did find a set of Hoosier stiff wall 29 10.50 X15"s that are supposed to be 1" narrower than I have now. I'm leaning toward them at this time. The MT 29" stiff walls are supposed to actually measure 10.2" wide but are 29.9" tall. The Hoosiers are supposed to measure the same as I have now at 29.3"
4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
|
|
|
Re: Launch problems
[Re: 68LAR]
#2112649
07/18/16 07:00 PM
07/18/16 07:00 PM
|
Joined: Jan 2003
Posts: 6,266
Renton Washington
Triple Threat
master
|
master
Joined: Jan 2003
Posts: 6,266
Renton Washington
|
3062S M/T 29.5x10.5 STIFF
3062W M/T 29.5x10.5W
18175 Hoosier 29x10.5W
I've run all 3 with no problems, all are stiff sidewall tires. Buy whatever one you wish, they'll be better than what you have. Like everyone else has said, RUN A TUBE!!!! 3900# stick car is hard on tires.
-Dustin
67 Dart, 9 second, 392" G3 Hemi
68 Barracuda 340 F/SA
|
|
|
Re: Launch problems
[Re: Triple Threat]
#2112659
07/18/16 07:09 PM
07/18/16 07:09 PM
|
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
68LAR
OP
master
|
OP
master
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
|
[quote=Triple Threat]3062S M/T 29.5x10.5 STIFF
3062W M/T 29.5x10.5W
18175 Hoosier 29x10.5W
I've run all 3 with no problems, all are stiff sidewall tires. Buy whatever one you wish, they'll be better than what you have. Like everyone else has said, RUN A TUBE!!!! 3900# stick car is hard on tires. [/quot
I already run a tube. I'm actually leaning toward the Hoosier 18175. It should be a direct fit.
4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
|
|
|
Re: Launch problems
[Re: 68LAR]
#2112697
07/18/16 07:54 PM
07/18/16 07:54 PM
|
Joined: Nov 2005
Posts: 690
New Hampshire, USA
oldiron
mopar
|
mopar
Joined: Nov 2005
Posts: 690
New Hampshire, USA
|
Hey Larry, what is your wheel width?
For what it is worth, ran both the hoosiers and MTs of approx the same size. Seemed to get more life out of the MTs, but the Hoosiers didn't leak w/o a tube. That was nice, but makes no dif w/tubes
66 Belvedere Vert, 4 Speed/Jerico, slowly, very slowly, getting faster - NA LD Wedge New New Best: 10.56 @129 68 B'cuda 4 gear Jerico - Another New Best of 9.86 & Trying to slow up https://www.youtube.com/watch?v=T4jDLKwd9Gs
|
|
|
Re: Launch problems
[Re: Monte_Smith]
#2112750
07/18/16 08:53 PM
07/18/16 08:53 PM
|
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
68LAR
OP
master
|
OP
master
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
|
Buy the MT. It's a better tire What about the difference in width?
4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
|
|
|
Re: Launch problems
[Re: oldiron]
#2112754
07/18/16 08:55 PM
07/18/16 08:55 PM
|
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
68LAR
OP
master
|
OP
master
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
|
Hey Larry, what is your wheel width?
For what it is worth, ran both the hoosiers and MTs of approx the same size. Seemed to get more life out of the MTs, but the Hoosiers didn't leak w/o a tube. That was nice, but makes no dif w/tubes My wheels are 10". I already run tubes, so that's not an issue. The MT's are taller but narrower.
4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
|
|
|
Re: Launch problems
[Re: 68LAR]
#2112773
07/18/16 09:11 PM
07/18/16 09:11 PM
|
Joined: Jan 2003
Posts: 10,038
MN
JERICOGTX
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 10,038
MN
|
The 10" rim is perfect for the 9" tire. It will allow you to run more air. Almost every stocker runs a 9" tire with a 10" wide rim.
69 GTX
68 Road Runner
|
|
|
Re: Launch problems
[Re: Monte_Smith]
#2112778
07/18/16 09:17 PM
07/18/16 09:17 PM
|
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
68LAR
OP
master
|
OP
master
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
|
Buy the MT. It's a better tire Just checked with Summit. Out of Stock til August on the MT's. So I guess I'm going with the Hoosiers.
4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
|
|
|
Re: Launch problems
[Re: JERICOGTX]
#2112779
07/18/16 09:19 PM
07/18/16 09:19 PM
|
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
68LAR
OP
master
|
OP
master
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
|
The 10" rim is perfect for the 9" tire. It will allow you to run more air. Almost every stocker runs a 9" tire with a 10" wide rim. Jeff, I'm not getting that warm and comfy feeling about running a tire that is that narrow. Summit is out of stock, but Jegs has them. I just ordered the 29 10.5 x 15 stiff walls. Thanks guys for all the suggestions. Really appreciate it.
Last edited by 68LAR; 07/18/16 09:30 PM.
4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
|
|
|
Re: Launch problems
[Re: 68LAR]
#2112787
07/18/16 09:34 PM
07/18/16 09:34 PM
|
Joined: Nov 2005
Posts: 690
New Hampshire, USA
oldiron
mopar
|
mopar
Joined: Nov 2005
Posts: 690
New Hampshire, USA
|
another FWIW The first time I ever dead hooked consistently on the convertible was with a 9" tire. Then could adjust the clutch properly. Also, best time and MPH. The stockers seem to get them to work pretty well also, you might check w/mccormack racing. had good dealings with them, tires come in measured/matched sets, and same age. They are worth calling and pretty fast http://www.mccormackracing.com/cgi-bin/l...p&order=123also, if you are an amazon prime member, same price, in stock, in fri but.....crap shoot w/size/age but can return
Last edited by oldiron; 07/18/16 09:39 PM.
66 Belvedere Vert, 4 Speed/Jerico, slowly, very slowly, getting faster - NA LD Wedge New New Best: 10.56 @129 68 B'cuda 4 gear Jerico - Another New Best of 9.86 & Trying to slow up https://www.youtube.com/watch?v=T4jDLKwd9Gs
|
|
|
Re: Launch problems
[Re: FastmOp]
#2112943
07/19/16 12:04 AM
07/19/16 12:04 AM
|
Joined: Feb 2012
Posts: 368
michigan
turbo toad
enthusiast
|
enthusiast
Joined: Feb 2012
Posts: 368
michigan
|
2x been using them for 25 years
Check out my build on Facebook Ttoad Hurley its updated regularly
|
|
|
|
|
