rear of car jumps on hard acceleration
#1
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Car: 91 firebird Formula 350
Engine: 350 TPI
Transmission: N/A, working on a t5 swap
Axle/Gears: 3.73 posi
rear of car jumps on hard acceleration
I feel like this is probably something with the rear suspension, but I'm really not sure where to start. I'm also worried that my diff. might be giving out.
When I take off hard from a stop, the rear of my car jumps and clunks. This just started in the last couple of days. Doesn't do it once i'm moving even under hard acceleration, doesn't do it if I accelerate gently from a stop.
First thought was trans mount but in my experience a bad mount doesn't cause the whole car to jump, and would still bang around if I floor it while moving. It also looked solid when I crawled under there.
any ideas? rear shocks? any chance of it being the rear end?
When I take off hard from a stop, the rear of my car jumps and clunks. This just started in the last couple of days. Doesn't do it once i'm moving even under hard acceleration, doesn't do it if I accelerate gently from a stop.
First thought was trans mount but in my experience a bad mount doesn't cause the whole car to jump, and would still bang around if I floor it while moving. It also looked solid when I crawled under there.
any ideas? rear shocks? any chance of it being the rear end?
#2
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Car: 1988 Gta trans am project 1-1/2
Engine: 86 4 bolt main cammed sbc 355 hsr
Transmission: 89 wc bw t5
Axle/Gears: Bw 9 bolt (3.27) pbr 11in
Re: rear of car jumps on hard acceleration
control arm bushings are dry rotted, if u still have the stock rear control arms i must recommend that u replace them with aftermarket tubular control arms from foundersperformance
#3
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Car: 91 firebird Formula 350
Engine: 350 TPI
Transmission: N/A, working on a t5 swap
Axle/Gears: 3.73 posi
Re: rear of car jumps on hard acceleration
Are the stock control arms really that bad? I dont have a lot of money so if i can get away with just bushings id like to just do that. Do i have to take control arms off to replace bushings?
#4
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Car: 86 Camaro
Engine: 355- hopefully a 5.3 this summer
Transmission: 700r4
Axle/Gears: 3.42
Re: rear of car jumps on hard acceleration
get the rear of the car up in the air and see what's loose.. the stock parts are plenty good for 99% of the people out there, so there is no reason to start throwing entire paychecks at after market parts companies to fix what is probably a loose bolt or something..
are you sure it's a suspension thing and not the exhaust shifting around from a broken hanger or something?
are you sure it's a suspension thing and not the exhaust shifting around from a broken hanger or something?
Last edited by novaderrik; 05-06-2013 at 11:01 PM.
#5
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Car: 1984 Trans Am
Engine: 305
Transmission: 700R4
Axle/Gears: Stock
Re: rear of car jumps on hard acceleration
I know you think it is not the transmission mount, but I have some experience with this. I had a loud clunking whenever a gear shifted. I put the ol' TA on jackstands and shook everything I could get my hands on. What I didn't do is push UP on my transmission just behind the crossmember/mount. When I went to the transmission shop to get advice, they discovered that the insides of the rubber mount had broken away. The outside of the mount looked fine, but I could lift the back end of the transmission right out of the mount. It was then, that I noticed some wear marks on the top (underside) of the transmission tunnel. Turns out the transmission jumped so hard that it would bounse off the tunnel. Thats when I parked the car and got a ride to the auto parts store to get a new mount.
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Car: 1989 Camaro z28
Engine: 305 tpi, stock
Transmission: 700r4 vette servo, shift kit
Axle/Gears: 3.73
Re: rear of car jumps on hard acceleration
The same thing happened to me when I was rolling around on my 24 year old OEM shocks. After I did a 4th gen 10 bolt posi swap and wanted to show off with some sweet burnouts, instead my wheels were jumping and i felt the huge clunking. The axle I put in had fresh gears and fluid, but I finally did a rear shock swap today and finally did the perfect burnout and powerslide without the rear end dancing up and down.
#7
Re: rear of car jumps on hard acceleration
I love posts like this. you don;t have alot of money to buy things to make things right, but yet you are telling the world how you beat the snot out of your car jumping on it doing burnouts and the back end is violently bouncing everywhere. You need to rebuild the car- it cost money- but not as much as it will cost when you finally break the trans and the rearend.
My best advice is if you cant afford to rebuild or better yet upgrade the quality of parts in a 25 year old car, then don"t do burnouts in it. If you take offense to this post? then you will learn the hard way and some day when I seee your future posts on repairing your trans or rearend I will come in and say I told you so. You said it yourself the car works fine if you are a decent driver, it only has problems when you beat the crap out of it.
Your problem is the shocks are old, the suspension busings are all worn, and when you jam on things hard from a stop all of this flexes and distrots and you are getting the notorious inverted wheel hop. Nest funny post will be someone telling you to simply buy relocation LCA brackets- wrong. You need shocks first, then you need new suspension bushings, and probably even springs if they have sagged so low they have poor geometry.
But save your money and don't bother, you'll need every penny you can muster up to repair the broken 10-bolt when if happens
My best advice is if you cant afford to rebuild or better yet upgrade the quality of parts in a 25 year old car, then don"t do burnouts in it. If you take offense to this post? then you will learn the hard way and some day when I seee your future posts on repairing your trans or rearend I will come in and say I told you so. You said it yourself the car works fine if you are a decent driver, it only has problems when you beat the crap out of it.
Your problem is the shocks are old, the suspension busings are all worn, and when you jam on things hard from a stop all of this flexes and distrots and you are getting the notorious inverted wheel hop. Nest funny post will be someone telling you to simply buy relocation LCA brackets- wrong. You need shocks first, then you need new suspension bushings, and probably even springs if they have sagged so low they have poor geometry.
But save your money and don't bother, you'll need every penny you can muster up to repair the broken 10-bolt when if happens
Last edited by SlickTrackGod; 05-12-2013 at 11:15 AM.
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#8
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Car: '89 Camaro
Engine: LS1
Transmission: 4L65/70E
Axle/Gears: 9 Inch, 3.70 gears
Re: rear of car jumps on hard acceleration
I agree with everything that Slick Track just said. I recently picked up a set of Founders control arms and panhard bar, but I'll be switching out the shocks also when I install them once I get back from Afghanistan.
#9
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Car: 91 firebird Formula 350
Engine: 350 TPI
Transmission: N/A, working on a t5 swap
Axle/Gears: 3.73 posi
Re: rear of car jumps on hard acceleration
Slicktrackgod, i take absolutely no offense to that post. And i have been babying it as of late. I need this car way too much as my dd to risk tearing it up any more than it already is. Thanks for the tips everyone, im gonna get it up on a lift soon and check around under there to see what i can find. Then ill be saving the money and fixing her as i can.
#10
Re: rear of car jumps on hard acceleration
Slicktrackgod, i take absolutely no offense to that post. And i have been babying it as of late. I need this car way too much as my dd to risk tearing it up any more than it already is. Thanks for the tips everyone, im gonna get it up on a lift soon and check around under there to see what i can find. Then ill be saving the money and fixing her as i can.
#11
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Car: 91 firebird Formula 350
Engine: 350 TPI
Transmission: N/A, working on a t5 swap
Axle/Gears: 3.73 posi
Re: rear of car jumps on hard acceleration
But, I do have an update to my original post. Me and my buddy got under there, and it actually was my trans mount. Again. for the 3rd time since I got this car. I'm glad it was something so simple in the end. But I'm thinking there's something more than just the occasional leadfooting causing that now. unless the new parts stores are selling really are THAT bad nowadays, there is no way I should be going through 3 trans mounts in 2-3 years.
#12
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Car: '86 TA
Engine: '74 350
Transmission: 700r4
Axle/Gears: 2.77
Re: rear of car jumps on hard acceleration
Get a poly mount. Mine was broken when I bought the car, then went thru 2 more rubber ones in the first year, just dd duty. Then went poly, still ok 10 yrs later.
#13
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Car: 88 Formula, 90 Iroc RIP, 92 RS Sold
Engine: 305 to 350
Transmission: 700r4
Axle/Gears: 10 Bolt
Re: rear of car jumps on hard acceleration
I love posts like this. you don;t have alot of money to buy things to make things right, but yet you are telling the world how you beat the snot out of your car jumping on it doing burnouts and the back end is violently bouncing everywhere. You need to rebuild the car- it cost money- but not as much as it will cost when you finally break the trans and the rearend.
My best advice is if you cant afford to rebuild or better yet upgrade the quality of parts in a 25 year old car, then don"t do burnouts in it. If you take offense to this post? then you will learn the hard way and some day when I seee your future posts on repairing your trans or rearend I will come in and say I told you so. You said it yourself the car works fine if you are a decent driver, it only has problems when you beat the crap out of it.
Your problem is the shocks are old, the suspension busings are all worn, and when you jam on things hard from a stop all of this flexes and distrots and you are getting the notorious inverted wheel hop. Nest funny post will be someone telling you to simply buy relocation LCA brackets- wrong. You need shocks first, then you need new suspension bushings, and probably even springs if they have sagged so low they have poor geometry.
But save your money and don't bother, you'll need every penny you can muster up to repair the broken 10-bolt when if happens
My best advice is if you cant afford to rebuild or better yet upgrade the quality of parts in a 25 year old car, then don"t do burnouts in it. If you take offense to this post? then you will learn the hard way and some day when I seee your future posts on repairing your trans or rearend I will come in and say I told you so. You said it yourself the car works fine if you are a decent driver, it only has problems when you beat the crap out of it.
Your problem is the shocks are old, the suspension busings are all worn, and when you jam on things hard from a stop all of this flexes and distrots and you are getting the notorious inverted wheel hop. Nest funny post will be someone telling you to simply buy relocation LCA brackets- wrong. You need shocks first, then you need new suspension bushings, and probably even springs if they have sagged so low they have poor geometry.
But save your money and don't bother, you'll need every penny you can muster up to repair the broken 10-bolt when if happens
I know its in my best interest. and more importantly my WALLET's interest :P lol but it can be hard to listen to dad's advice, when the damn car is just so FUN! haha but I'm starting to realize that you're better off driving your car a little slower and enjoying it for a long time, instead of driving it hard for a couple months and having it down for a couple more because you broke something else. my list of things to fix is already too long I don't need to be adding more by driving it too hard.
But, I do have an update to my original post. Me and my buddy got under there, and it actually was my trans mount. Again. for the 3rd time since I got this car. I'm glad it was something so simple in the end. But I'm thinking there's something more than just the occasional leadfooting causing that now. unless the new parts stores are selling really are THAT bad nowadays, there is no way I should be going through 3 trans mounts in 2-3 years.
But, I do have an update to my original post. Me and my buddy got under there, and it actually was my trans mount. Again. for the 3rd time since I got this car. I'm glad it was something so simple in the end. But I'm thinking there's something more than just the occasional leadfooting causing that now. unless the new parts stores are selling really are THAT bad nowadays, there is no way I should be going through 3 trans mounts in 2-3 years.
And if you don't want too then I don't know what to say
Cheap = Broken Parts = More $$$ then after spend $$$ you then spend more $$$ to do it right lol
So upgrade the needed maintence items like shocks bushings etc due to fact it's sometimes a chain reaction on some parts breaking and to stop the chain all parts related to the broken parts need to be check and addressed as necessary
Are you using rubber mounts ?
Need to do some reading
https://www.thirdgen.org/forums/tran...ison-pics.html
https://www.thirdgen.org/forums/tran...h-8-eight.html
Last edited by Zach/90\irocZ; 06-13-2013 at 09:47 PM.
#14
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Re: rear of car jumps on hard acceleration
Go for energy suspension tranny and motor mounts. I went through 4 tranny mounts + 3 sets of motor before I went with poly urethane mounts. also get a umi torque relocation kit can use the stock or you can upgrade later, the 3 third gen f body torque arm design worst gm mistake ever.
http://www.hawksthirdgenparts.com/pr...%26-700R4.html
http://www.hawksthirdgenparts.com/pr...%26-700R4.html
Last edited by KITT1983; 06-26-2013 at 07:41 PM.
#15
Re: rear of car jumps on hard acceleration
Hey guys love the advise, I just recently 1n1/2 years ago installed bilstien shocks on my 2001 Silverado2500hd LT4x4. I do not drive her hard, shes my work truck and I love her so much. I have some hopping issues when I get on dirt roads, was thinking the ride should be smoother... thinking it might be something similar? Anyone have any thoughts?
#16
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Re: rear of car jumps on hard acceleration
Stop driving on dirt roads
Hey guys love the advise, I just recently 1n1/2 years ago installed bilstien shocks on my 2001 Silverado2500hd LT4x4. I do not drive her hard, shes my work truck and I love her so much. I have some hopping issues when I get on dirt roads, was thinking the ride should be smoother... thinking it might be something similar? Anyone have any thoughts?
#17
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Re: rear of car jumps on hard acceleration
This is a 82-92 Camaro/Firebird message board.
Check out www.performancetrucks.net for help with your truck.
Check out www.performancetrucks.net for help with your truck.
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