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Romulus22 08-25-2018 07:47 PM

Critique my cars launch
 
Im looking to improve my 60’. After taking a slo mo I’ve got more wheel spin off the line than I thought. In this video the tire pressure was low, 7.5psi. I brought it up to 10psi but I’m still in the best 60’ times of 1.48. When I had the tires at 12-15psi it didn’t seem like I could break out of the 1.5 range.

The car has stock style suspension rear with torque arm. Nothing is adjustable except pinion angle, new stock style shocks.

The front is stock suspension running competition engineering shocks setup in 90/10 dampening ratio.

Running a power glide with brake currently set at 4500 on the two step.

What are some suggestions you guys think I should try next time out. Which will be at LS fest where I’m hoping they will have better prep too.



ragtopz28 08-25-2018 08:32 PM

I think you should invest in some double adjustable rear shocks.

jhshnh 08-25-2018 08:33 PM

How much of a burnout are you doing?
What is your pinion angle?

Looks like your front end transfers just fine, maybe some adjustable shocks for the rear?

Romulus22 08-25-2018 08:40 PM

Without climbing under the car and checking I don’t know the pinion angle off hand. Here’s another video including a burnout.

Just so I’m understanding and learning how do the adjustable shocks help in the rear?


ragtopz28 08-25-2018 08:55 PM

A good set of DA shocks will allow you to adjust compression and rebound of the shock. Because it is a torque arm car, loosening the rebound will plant the tires harder. You want to see some "lift" in a torque arm car. Not squat.

Romulus22 08-26-2018 03:41 PM

I ordered some QA1 double adjustables. And I looking to set them up like the fronts since it’s a torque arm car. Fast rebound slow compression?

Doug G 08-26-2018 03:56 PM

Looked like the rear tires are bouncing or tires wading up.

Tires at 7.5-10 was the same 60'...……..and 12-15 to 1.5's...…….guessing somewhere in between there could be the magic number.

4500 off the brake/2-step...……..maybe play with launch rpm ? .........500 less to start ?

Have you looked into a wider wheel or taller tire ?

And yes, DA shocks will help too.

ragtopz28 08-26-2018 04:31 PM


Originally Posted by Romulus22 (Post 19956118)
I ordered some QA1 double adjustables. And I looking to set them up like the fronts since it’s a torque arm car. Fast rebound slow compression?

Think of it this way, when the rebound is loose(r) the rear of car will "lift" therefore planting the tires harder. Your car is squatting in the first vid, the second doesn't look too bad...You are going to have to play with it and those up close, slo-mo vids are a huge help. If it hits the tires too hard the car will plant and then unload spinning a little further out. I don't think this is you case. The driver rear appears to be shaking harder than the passenger side. Do you have a ARB/Drag bar?
Doug G brings up some excellent points. Obviously, with that low of a pressure you are running a bias slick. Is it a soft or stiff wall? 10psi would be the minimum IMHO on a slick. Radials like 17-18 in my experience.
Tell us more. What tranny, gears, tires, etc.

Romulus22 08-26-2018 05:13 PM

The car does have a competition engineering anti roll bar. It’s hard to see once I download to YouTube but going frame by frame zoomed in the tires appear to travel at the same rate. And it picks the front wheels equally.

I agree 7.5 was def too low of pressure. In that video they were wadding up and “snapping”. My friends got more videos later in the night but the lighting was messing with the slow mo. I’m going to try to get one of those and post it tomorrow. So far 10-12 psi seems to be my magic number, best of 1.481 60’, the 7.5psi run was a 1.531 60’. Not to say as I change things another pressure won’t be better.

My my two step was originally set much lower. Raising it helped but I haven’t played with it much at all.

The cars body pretty much limits me to a 24”x8” slick. My street tires are closer to 26” but you can’t fit a finger in between the front and rear of the tire to the body. I don’t want a slick expanding and contacting causing a blowout on the top end. As much as I know a larger tire will help I want to save this for last so I don’t have to chop fenders. They are already lip rolled to prevent contacting.

The slicks hold the weight of the car without wrinkling under normal sitting and driving. I was shocked to see them wrap up like that. I’m not sure if theyre a soft or stiff wall slick.

The first video was on brand new gas charged shocks. The second videos the shocks were new’ish but cheap and completely blown. They had no gas charge left.

Lastly the trans is a freak show performance built power glide 1.76 first gear. Rear end is a moser built 9” with 3.00 gear and spool.

Thanks for for the help guys, I’d like to see what the car is capable of pulling a low 1.4 or even a high 1.3 60’

Romulus22 08-27-2018 05:46 AM

Here are the other videos my friend took. The first one from the passenger side is my fastest pass to date and my fastest 60’ to date, 10.41-1.481 both of these passes are with the tires at 10psi


This is a drivers side view with a 10.48-1.489


Doug G 08-27-2018 04:36 PM

Looking at the 2 new posted vids....shocks ! Looks like next to no control of the rear suspension
Tire air pressure was close to perfect

ragtopz28 08-27-2018 06:36 PM


Originally Posted by Doug G (Post 19956808)
Looking at the 2 new posted vids....shocks ! Looks like next to no control of the rear suspension
Tire air pressure was close to perfect

Yep, put those DA's on, start in the middle, and post up some more vids.
It's gonna work good soon!

Doug G 08-27-2018 07:14 PM

You're looking for the front to rise and the rear to stay flat or rise some. No rear squat.

Lots of examples......and some not so much.

Romulus22 08-28-2018 06:37 AM

I was pretty adamant I wasn’t going to buy good shocks anytime soon. Hopefully next year I planned on chopping a lot of the car up and I was going to a trailing arm setup with coilovers. The fronts were pretty cheap and I didn’t think the rears were that bad and spinning that bad. But I’m looking to give myself the best chance I can for this years LS fest East.

Thanks again guys guys I’ll report back with some new videos/times after the new shocks.

handyandy496 08-28-2018 01:38 PM


Originally Posted by Romulus22 (Post 19957068)
I was pretty adamant I wasn’t going to buy good shocks anytime soon. Hopefully next year I planned on chopping a lot of the car up and I was going to a trailing arm setup with coilovers. The fronts were pretty cheap and I didn’t think the rears were that bad and spinning that bad. But I’m looking to give myself the best chance I can for this years LS fest East.

Thanks again guys guys I’ll report back with some new videos/times after the new shocks.

I noticed that in slow motion I can see that the tires are grabbing well at launch. Right away the front's start to lift(Too quickly?). When they reach the end of there travel the rears start to spin. This is very hard to feel but it shows up big time in slow motion.
Same with my car but starting with 315/35/17 nto5R's. Going to 28/11.5/16's Hoosier dr2 radials made all the difference. The taller Hoosier took out the violent hit at the start and let the car pull up to the top of the shocks and stay there without the front coming back down forcing the rear wheels to spin after I already hooked and was moving.
I was using stock shocks with over 130,000 miles. Went from a 1.64 60ft with a really violent hard hit jerkin my head into the headrest to a 1.52 60ft with a much smoother launch. Going to more of a slick I put in frame rails, this was the only change going from the 17" 25.5" tire to the 16" 28" tires".
In conclusion I would say tire rim combo first then fine tuning with suspension then gears and shocks last. Unless you feel you need to gear it back to where the smaller diameter put you. That would be pulling the 4:10's for 4:30 or 4:56's for me. That would get my head slamming back into the seat more where I liked it better. lol.

Romulus22 08-29-2018 10:35 AM

Tires first is a no go, I’m out of room in the body. Tuning suspension is almost a no go, I don’t have multiple lower control arm positions. Gears are never going to change, unless it’s for more gear so it’s nicer to drive on the highway. It’s already crossing the line at 6k as it is. I got my shocks in the mail yesterday and will be putting them on today. I’d like to test this Friday but Ive already got other plans.

Doug G 08-29-2018 05:19 PM

6000 scares you ? I shift at 7-7500 ….let her eat man.

I feel you on the "better hiway manners" though.....3500 @ 65 gets old pretty quick anymore.

Romulus22 08-29-2018 05:26 PM

6000 doesn’t scare me. But if I remember right my engine take a nose dive at 6500 and the rev limit is set at 65-6700. I’m shifting around 6500. You can hear me tag the rev limiter on the very first video because I was getting a little out of shape.

Doug G 08-29-2018 06:33 PM


Originally Posted by Romulus22 (Post 19958307)
6000 doesn’t scare me. But if I remember right my engine take a nose dive at 6500 and the rev limit is set at 65-6700. I’m shifting around 6500. You can hear me tag the rev limiter on the very first video because I was getting a little out of shape.

Aaahhhh, OK. I thought you were worried about going 6000+...….understand now.

Romulus22 09-09-2018 05:10 PM

LS fest was really busy. Only managed to get two runs in. This was my best. I might have to blame a little bit on my burnout though to be honest. Just wanted to get an idea if my suspension looks better?
QA1 shocks set on 8 clicks compression 3 rebound. Tires at 12psi. 2 step at 4K.



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