Traction improvement suggestions?
 

After setting up a limited slip axle and adding slicks what is the next smartest thing a guy can do?

First tell us what body type you are making these improvements on, like is it leaf spring, or coil?

Go to the track, get a few back to back runs and then go from there

Probably Blizzaks or maybe BFG all-terrains.

Oh wait, wrong forum ... my bad!

Hope it don't rain....

Is this a street car?



Frank

Yes! In regards to the above post as far as going into a tight turn under hard throttle on a wet road, lol!

It’s a great way to go back to where you where headed from and get your knuckles instantly white!

BTDT a few times!

Ok back to your question.

Replace your hollow greasable stock type U- joints with race ones and then also add a driveshaft loop, this all assuming your driveshaft still has good wall thickness!

Duh, some data might be helpfull eh?

1967 GTO, 3.23, 428, TH400 with Cliff influenced 9.5 inch convertor. Rear sway bar/boxed control arms. Rear frame reinforcement bars. These noticeably stiffened up the car BTW. Factory replacement springs with coil over shocks which I suspect might be an issue.

In that case get a set of what’s called Hop Stop bars/ anti hop bars.

Also what’s the HP level planed for the motor, and or the ET you would like to turn in the 1/4 mile?

If your looking for making more then some 525 hp then fuel system up grades will be needed while we are talking about working on things under the car.

Steve25 - appreciate the strength and enhancements.

Steve 65 GTO - know where I can get a lift kit- ?!

Bill - I've had it to the strip once and did a best 13.582/103mph. Was with a stock convertor and marginal limited slip and limited experience : ) An error I think I did was to load up the trans just under 1,800 and "eased" it off the line and then laid into it best I could

That's a good start.

1. Replace the body bushings and whatever body bushing hardware is needed--probably all of it. The frame is a flexible mess until it's securely bolted to the body.

https://www.chevelles.com/threads/bo...-body.1131908/

2. Verify rear ride-height. The taller the ass-end is, the worse the traction is likely to be.

3. "Drag strip" traction is enhanced with tall, soft springs in front, and drag-race shocks. But that's a disaster on the street, which favors short, stiff springs for handling and braking. OEM springs are closer to the tall/soft drag ideal than to the short/stiff "handling" ideal.

4. My "A-body" '68 'Camino has No-Hop/Hop-Stop bars on the rear axle. Some folks don't like them, but I'm happy with 'em. Mind you, that thing hardly gets driven, and has never been to a drag strip. I plan to change that...someday.

5. A "posi"/limited-slip differential that actually works.

6. If the rear frame-stiffening bars made that much difference...I'd be looking for cracks in the frame.

I'll look up the hop shop's. Are they bolt on, is there any drilling needed?

Cracked frame, yikes.....I may have exaggerated a bit. I'm up on jack stands right now so will able to have a good look around.

When I put them on it wasn't addressing an issue as in feeling major loose or something like that, just thought if they were added for manual cars it won't hurt to add them here too.

I'm sure the body bushings have been there from the beginning and I can imagine new would really stiffen things up

Gotta drill the axle housing in the webs. There's more than one part number for the No-Hop bars, depending on which axle you're installing them on.

And you'll want to be careful about where in the web you're drilling, so the U-joint angles are correct when you're done.

The reason they were installed by gm to begin with was to "cure" a frame-cracking problem. It's worth a look on your frame.

Read the article at the link I provided. The run-on words and lack of proper bullet points is not my fault. I'm gonna have to jack them up about making some corrections. Point is, I could tell the car was more rigid just by jacking it up to take the jack-stands out when I was done installing the new ones. I didn't even have to drive it to notice the difference.

Fresh body bushings made a TREMENDOUS difference on my 'Camino. Keep in mind that the 'Camino has the "rigid" fully-boxed frame rails, and the frame is still a wobbly mess when it's not bolted to the body.

It's hard to put into words just how much better the Eaton Truetrac vs other styles of limited slip differentials. I highly recommend them.

Fresh body bushings made a TREMENDOUS difference on my 'Camino. Keep in mind that the 'Camino has the "rigid" fully-boxed frame rails, and the frame is still a wobbly mess when it's not bolted to the body.


Reminds me that I have to do something with my 50 year old body bushings

Thanks Bill for body bushing replacement link. When I'm under there to put the trans back in, and looking the frame over for cracks/damage etc., I'll be noting body bushing interfaces for their condition.

Steve25, I missed your query about my goals. I want to be in the 12's and low would be great. I have to be sensible at this time of family raising so am ensuring I make responsible and efficient steps towards future "growth."

And folks, this is why I really appreciate your experience and insight.

In addition don't forget to update control arm bushings.



Frank

Seems like I've seen more frame flex than cracking. This photo is of a friend's '67 quarter panel. He had the factory 4-speed frame stiffeners in place since new but over time the bolts had loosened which allowed the bolt holes to hog out and effectively negate any ability to stiffen things up.

Anything over about 1-1/2" lift in the rear will get you into wheel hop. Best to stay close to stock control arm angles.

Heads, cam, stall?

The next step is to run it again with a good tire under it.....you may not need any other improvement at the moment.

Just Guessing, but at your current power level with slicks you should have zero traction problems?

If you do find the need, you might want to loosen up the front suspension by removing sway bar, loosening end links, drag shocks etc etc as others have mentioned.

Fun times!

With slicks, this right here ^ ^ ^ is the best advice so far.

You'd be surprised just how easy a driveshaft can cut through a floor pan. If that happens you may never have to worry about trimming your toenails ever again. If you know what I mean.

That’s why I posted it !
In a friends F body WITH a driveshaft loop he had the thing still fail and bust thru the floor only 1 inch away from his seatbelt hold down on the side of the tunnel,

Had he not had the loop it would have grabbed That seat belt , pulled it tight and just cut him right in half!

https://forums.maxperformanceinc.com...5&d=1613092040


I was just about to ask if your friend has a You Tube channel.

Take a look at this video, this guy actually replaced the original

body mount bushings with poly's and the problem got worse.

https://www.youtube.com/watch?v=-NdFIAt7ysE



Frank

Interesting !

Think the take-away is you can't ask the body to do the work the frame should be doing. Until frame flex is eliminated it will be transferring the flex to the body and the stiffer mounts simply asked the body to do more of the work. Leaving softer mounts in place doesn't do anything for the launch, but it does prevent additional flex transfer.

Solution has to be in stiffening up the frame. I went back and retightened my brace bolts on the street car and called it good because it no longer sees track time. My friend with the quarter problem purchased some very nice tubular braces that look like they will be much stiffer than the stock angle pieces. Unfortunately in his case it is like the old adage of closing the barn door after the horse gets out.

Add a driveshaft loop?��
And see what breaks next! ��

X10 on the driveshaft loop so you're legal at the track and check u joints. Make a couple passes and get a baseline.. If your rear is an 8.2 start planning on a replacement. High 12s doesn't require major mods

Rear axle shafts and engine mounts.

At your power level you really won't need much. 13.50's at 103 is a great start, and tells you the car is already capable of high 12's as is. I've gone mid 12's with completely stock 50 year old issue suspension without anything more than a sticky tire. I eventually pushed that car to 11.70's with more engine, with a not so great 60 foot, and all I had done at that point was unhook the front sway bar. The car would eventually go 11.40's with no hop bars, adjustable shocks. Very basic setup for very little money. Basically the same setup my father is going 10's with and cutting 1.4 60 foot times.

If you don't plan more power upgrades, and since you already have some sticky tires, I'd make a trip back to the track with the new tires and have some fun with it. See where you're at, how the car does, and then make some decisions before spending money on other things you may not need at all.

My bird is going nearly 13 flat (high 12's corrected) and everything on that car is 50 years old. There are no aftermarket parts in the suspension anywhere. Just modified the front control arm bushings and sway bar bushings to allow a little more front end movement, it has oil filled shocks, the rear suspension is untouched with stock replacement 50/50 gas shocks. All the springs are original issue. I've spent literally no money on the suspension, lol. At that power level it just flat out works, and still daily drives like a stock car should.

Best of luck, most of all, have some fun!!

It is a fun journey for sure going from 13s to 11s. The video camera on slow mo is your best friend. Make a change, go test and video.

The people on these forums then can give you great advice. I got tons from these awesome people. I ended up 11.71@118 and reliable as hell. Started with a totally stock 70. Did Drag Week 2019 zero failures.

i'd go for a driveshaft loop next!

Good sticky tires, good or upgraded u joints and a driveshaft loop and go from there.
I'm into the 10's and my biggest traction aid is sticky tires. Stock suspension second gen Firebird with just cheap 3 way front and rear shocks.

I agree, good tires on a stock suspension in decent condition is all you need well into the 12’s and beyond.
If you’re going to do some serious bracket racing there are some things you could add that may help consistency but you won’t go any quicker.

Thanks everyone for laying out a sensible and cost efficient plan. I have a grocery getter compared to all of yours and thanks for your time.

1 or 2 fifty pound sand bags behind the back seat - in trunk.

For under $700, UMI makes a pretty attractive rear kit. https://uploads.tapatalk-cdn.com/202...45cff4e5fd.jpg


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^^^If you're going to go through the trouble of replacing/updating the rear control arms with UMI products, I'd recommend opting for their Roto-Joint spherical bushings rather than the standard polyurethane.

A few years back. I had about 150 lbs of softener salt in my trunk to aid traction on a cool night. When the car hooked after the first pass and we realized the track wasn't that bad..we quickly pulled the bags out and picked up another tenth and a mph real quick. Weight helps if you want to tune your 60ft as far as carb or timing if you are traction limited.

Look at what gears you have? Definitely want a stall converter depending on cam and gears,minimum stall converter at 2800, drag radials, stiff poly bushings, practice your launch..start there..

You can double-duty a street/strip car with good adjustable shocks, but not cheap.

Yes on the roto joints or the GW ones.

Body bushings are a touchy subject for many, but to throw it out there, solids are the way to go. People that say they increase road 'harshness' I doubt have ever really tried them, because it's just a farce.

.

No hop bars. Adjustable upper control arms so you can set pinion angle. Large rear sway bar. 90/10 shocks in front with 50/50 rear. Air bags in coils to preload to counteract torque twist. Frame stiffeners. My 66 GTO used to twist terribly. These changes made the launch even, both front tires about 2” up. See pic.