schlosser1

I have a 67 gto with a ls1 and a 6 speed i am getting a high speed vibration that seems to be driveshaft related. im not sure if its pinion angle but it is pretty close at the moment. i was wondering if anyone out there was or has had the same issue above 80mph. Driveshaft is 3.5" aluminiumn which is new and 100% ballanced. 4.11 gears in the stock 10bolt with eaton posi. wheels were balanced last week also . the usal stuff has been checked and now im pulling my hair out. any helped would be appreciated.

did you have to do major modification to the trans tunnel to get it corrected?

Thanks,
Josh

stealth71

iTrader: (15)

What did you set your trans output angle at?

If you didn't cut your trans tunnel at all you angle is probably off.

Kurlee Daddee

Pics or BAN!!!!!

67' GTO is my dream car!!!!!

72ChevelleConv.LS1

iTrader: (5)

Probaly has to do with trans to rear end angle. They say 2 to 3 degrees is best for each they can be up or down.

bczee

iTrader: (12)

well.. could also be rear diff wheel/axle bearings !?

What else was changed or when did this start ?.. a little more back ground or info .. Else we are all taking shots in the dark..

What rpm or mph does it start and does it stop after you get above any speed or rpm's ?

schlosser1

Ive have had 4 different driveshafts in the car, the first was .065 steel 3 inch it broke in half at 120+ mph " scary " the second was 083 wall and had harmonic vibration at 65+mph with 411 gears, had it rebalanced and still did it, The third was 3 inch aluminumn and did it at 80+mph the guy said it might be too much rpm for the size of the driveshaft, SO he buit me a 3.5 aluminumn and it got much better but is still there. The rear is all new, had axles straightend. I think it might have to do with tranny output angle but every thing i read tells me otherwise

schlosser1

I am going to try to have the ds come out as staight as pssible out of tranny and go from there, lots of cutting .stupid little tranny tunnel.

mullenh

iTrader: (1)

67 pontiac ls1 with a4, did have to cut and enlarge transmission tunnel, had to notch the cross member (to make room for the ac compressor) and cut some fire wall too.. looks good now though.
what did you do for gauges? speedo, tach, etc.. I've got to replace mine.

schlosser1

I cut out the whole gauge cluster out leaving a a 1" lip all around for something to mount to and put in a piece of black pvc , then i marked out the gauges before cutting so i could see how it looked. I used autometer sport comp gauges with programable electric speedo and hooked into facory wiring.if you need help let me know I could put up some pics, Ive had my car with ls1 driving for over a year. with stupid vibration. what angle do you have coming out of tranny?

schlosser1

do you hav pics?

mullenh

iTrader: (1)

thanks! i thought about doing that with the gauges and reskinning face plate. first i wanted to try to get replacement eletronic gauges that would fir in stock location. i do have pics and i will try to post soon er I might have to get my kid to do it :/

how did you mount your engine to the cross member? did you keep the ac too? and how much cleareance did the alternator have?

schlosser1

I ended up using the corvette accesories, the motor mounts were chevy 350 small block ones ,I made adapter plates from aluminumn to bolt them on the ls1, The oil pan i cut and had welded and i had to lenghten the oil suction tube, i made a high mount ac bracket that worked out real nice but i have not finished all the lines to the vintage air unit, on my list of a million things to do. oh i also used 67 chevelle steel mounts that almost bolted right up to the gto frame i had to drill some holes funny cause they are the same frame as the gto.

schlosser1

street and performance has some cool instalation links on there home page that is were i got alot of my planning from. I have seen the use camaro accesories but the motor is real high and pushed back. have you just stated thi project?

schlosser1

started

schlosser1

I put a 228 cam in the gto, still has manifolds,put ls6 intake on and the car has done a best so far at the track of 12.4 at 112mph and a 1.9 60 foot the car weighs 3720 with me in it a a full tank of gas. just in case you were interested.

badpewter-z

iTrader: (4)

adjustabe upper a-arms back in yet?

schlosser1

no but they will be soon ,not like it will matter.

stealth71

iTrader: (15)

Have you measured the trans and pinion angles yet? I think you should probably start there considering you have replaced the driveshaft.

I rasied my trans tunnel about 1" to get as close to 3* as possible, but it is a '71 Chevelle w/ BRP style mounts.

schlosser1

the tranny angle was 3* down and pinion angle was 3* up. I have adjustable upper control arms so i can put the rear angle any where but it still didnt matter no matter were i put it still had vibration, thats why i am going to put the tranny up until the driveshaft comes out straight. i cant think of what else to do

stealth71

iTrader: (15)

What type of gauge are you using to measure the angle? It might be off. I wish I could afford a nice digital one.