Thread: Car wobbles when racing

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Ok so ive got a Datsun 280z with a blown 350 sbc and th 350 in it . When i really give it the gas the car feels like it wobbling or shaking . I have solid mounts everyplace and the car is in great shape but ive never dealt with 400 horses in a 2,600 pound car .

Is it just the force of the torque making it wobble or vibrate maybe cause the car is so light ? everything is balanced except the front tires havent done that yet lost the lug key

Jason

Yeah it could be tire balance, or it could be the front end. you might need to play with caster/camber settings. Hank

I had a Pinto with that problem. Had an Olds 455 in it. The car just kept trying to lift off of the track. I finally had to shift the balance of the car way forward.
I extended the nose by 10" and moved the motor forward, and then replaced the rear suspension with a heavy duty leaf spring setup out of a 1970 Chevy station wagon.
To make up for the loss of weight in the rear I ahd to go for some some MT 15' P235 street slicks.
The car looked kind of odd by the time it was done, by I ended up with a normally aspirated Pinto running in the low 9's with a stock 455 from a 1970 Olds Delta 88.

What kind of tires are you running? You could be experiencing some mild tire shake if you hitting them hard...
Mark

sure it was stock there? if that was true an ls6 should make a vega run 9's lol

Originally Posted by Shrug

I by I ended up with a normally aspirated Pinto running in the low 9's with a stock 455 from a 1970 Olds Delta 88.

ill post the tire brand tomorrow But my suspension is exact like a crovette in the rear 2 coil springs and a solid mounted diff with half shafts . i have stiffer springs then stock not sure the stiff number but plenty for the stock six cylinder . Tires are 15 tall and 10 wide but the front end does lift up so so much that when doing a burn out the front tires leave black marks . It lifts the front tires so much that the rears grab and push the front tires along to leave marks on the road .

Seems my front end doesnt grab enough i assume not bad for the horses im putting down in a 2,700 pound car thanks everyone

Jason Blown SBC datsun 280z " My dream car is a 69 Plymouth 440 GTX " Ouch but love is blind

something is way out of wack here.if ur front tires are leaving black marks
take ur foot off the brakes. what kinda 60ft times what is the mph. 15 is a pretty short tire.as far as that pinto goes,WOW, hell of a 455. that Datsun rear suspension may not be suited for drag racing. in the early 60's they put
regular rearends in Corvettes for drag racing purposes. the irs never worked,the rear wheels would toe in really bad with big horsepower

I would check all of your settings in the front suspension.Saying that, they will change once the suspension is lowered ,chassis being raised by WOT keep that in mind.Try using some suspension travel limiters.What you could be experiencing maybe Bumpsteer?Also if you feel it on take off,mid track ,or the end,get someone to video your run.You can then analyze what your car is doing from outside the car.

Like the guy above said also, all your problems could be coming from the stock rear.I am sure it can be tuned out ,though.

i think rear irs susp toeing on hard acceleration and as the tires slip a little and unload the susp unrravels on that side and back and forth you go.
i had this happen on my bucket with soft rear leaf springs(last leaf removed), i watched the susp and rear axle move forward and back unevenly as the tires grabbed and the springs wound up. i stopped it with a set of long homemade slapper bars and putting the leaf back in.
your case is a little different with irs ,any way to firm up the front rear movement of the rear would help. it may look solid but you would be surprised what torque will do.

Well ill see if i can stiffen up the rear with stiffer springs if i can find any . I set the rear up for this mod as far as the diff goes solid steel diff mounts molly tube rear controll arms custom made thicker mustache bar to hold the diff also .

The front suspension is stock besides the lowering springs and custom billet aluminum controll arms the deal with the front tires leaving black marks is that if i try to do a burn out depending on the road i am on at times the rear will squat so hard that it lifts the front end and shoves the tires along the road while my foot is still on the brake only happens once in a while .

Ill try to elimnate the squat first and see what happens thanks for the help all .

Jason

You don't realy expect the front tires to hold that car while you hold the gas pedel to the floor . Do you use a line lock?? Dosen't sound like it.

ya like this guy above is saying the front tires will usualy break lose during a burn out.I think stiffening up the rear end will help in keeping the front end from breaking lose.Are you still using rubba bushings? If so you will at least need polyurethane bushings,if not some stronger.JMO

Yep a B@M Line lock and a trans brake when i choose the trans brake that is

"I hit second gear and slide sideways about 2 feet" Pissed off a lot of mustangs lateyl hee hee

I say if ya think ya got it bring it man

No rubber or polyeruthane i used solid metal mounts nothing less chrome molly tubings billet aluminum etc etc