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i dared to boost!

2K views 31 replies 9 participants last post by  xassh 
#1 ·
but only in fifth gear.

man, it's good to have her back on the road. 750 miles on this trans and it's still together. well, 750 in this car and no, i won't boost in first, second or third because the shifter starts to vibrate horribly once over 4psi

 
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#4 ·
i realize now that i really could not even begin to check out the trans while it was in the donor car.

the fuel pump in that car was dying.
cylinder #3 had zero, yes, zero compression.
but, well, atleast is shifts smoothly
 
#9 ·
Looks like your SRS light is on, that funny because you don't have an airbag.

Am guessing its from your donor car.
 
#12 ·
the front mount is a new 'solid' style mount, the rear two are both used solid style out of the '86.

i am starting to think that maybe it is the drivers. the pass. side driver on the '86 trans is the original, though the driver's side is from the spare trans in my garage, which came out of my '92 after i seized the trans. that driver has a supposed 218k miles on it, so i am starting to think that maybe, just maybe, it is a little worn and therefore causing the vibration that i am feeling.

the vibration certainly is at it's worst in third gear, not so bad in fourth, but now that i am looking for it, i do feel it some in fifth gear as well. it would make sense that i feel the vibration most in third, espcially in the shifter, due to not only the gear ratios but also the location of the shift rod. in third, the rod is out of the trans as compared to in fourth the rod is in the trans. it works like a lever, creating a feel of far more vibration.
 
#16 ·
yes, but wouldn't the wheel speed also affect this?

still, the vibration seems most pronounced in third.

i will go test drive and report back. i need to go to the store anyway, i'll take the scenic route
 
#17 ·
I had major vibrations in a car I brought back to life once. It was only under hard acceleration, and typically only in 3rd and 4th gear.

The problem: worn inner driver on the passenger side. Replaced it and the car ran great, no shimmy even when balls out FWOT in 3rd and 4th.
 
#19 ·
first gear = no problem

second gear = no problem noted from closed throttle to 10 psi

third gear no problem with cracked throttle, vibration starts around '0' on the pressure gauge, working its way up to a bad vibration with 10psi on the manifold, felt in the shifter, gas pedal/floorboard and the seat of my pants. there is absolutely no feedback thru the steering wheel.

fourth gear, no vibration with throttle cracked thru '0' on pressure gauge. minor vibration noted around 4-5psi, getting slightly worse up at 10psi. not nearly so notable in the shifter, but still felt thru the gas pedal/floorboard and the seat of my pants.

fifth gear, no vibration with throttle cracked up to '0' on pressure gauge. vibration noticed around 5psi, getting slightly worse at 10psi, though notably higher in frequency, the vibration is not nearly so severe in fifth as it was in third. none felt in the shifter at all, was notable thru the gas pedal/floorboard and seat of my pants.

i am thinking now, turbo and or, inner drivers. these axles were both rebuilt and have about 60k miles on them. driver's side inner driver cup has 218k miles on it and pass. side inner driver cup has, hrmm, i cant recall what was on the clock of the donor car when the trans came out. i think it was around 140k-150k. maybe i have that speedo in the garage. will check tomorrow mebbe.
 
#22 ·
makes sense to me.

ok, so the conditions described in my 'test run' last night do not always apply.

i boosted in third while getting on the freeway, on my way home a little bit ago. the vibration was far less than usual. the freeway came to a stop and when i had a chance to use third again, the vibe was back, as bad as before.

i do think the turbo would disintegrate long before it caused enough vibration to move the shifter, for example, i never even felt this, just heard a loud pop! and suddently and seriously lost power. (happened a while back)

 
#25 ·
more notably now than before, i have been hearing a bit of a 'whump whump whump' at low speed (10-20mph) and a bit of a 'squeak squeak squeak' in the 25-35mph range. i wonder if the vibro could be the wheel bearings.

i'll get em done soon, will also check cost on inner driver bearings... since i will all ready have the hub off for the wheel bearing, would be quite easy to pull the axle too.
 
#27 ·
i don't dare ask about if you did...

the bearing has been quiet the last couple of days, though i do still get vibration while boosting.

mebbe ill get the car off the ground tomorrow, i've worked 50+ hours the last 4 days and am beat.
 
#28 ·
well, shit. last weekend i drove out to Temecula to pick up that EVO 8 FMIC, from there i went south to visit a couple friends in San Diego. everything felt fine until i was on my way home and i started getting bad vibrations any time i applied enough gas to accelerate, or even keep me from slowing down.

the vibrations are getting worse.

first and second gear are fine... unless i am at the top of the rpm range in second. third is worse than second, fourth is worse than third and fifth, well, i keep thinking my radar detector is going to get shaken off the windshield.

i listen to the radio now, because the cd player doesn't like to play with vibrations like i am getting. it is kinda scaring me, just a little bit :p

the problem is certainly based on speed, the faster i go, the higher the frequency of the vibration. the problem is also based on power output. i dont have to be boosting, just giving it enough power to maintain speed will start the vibrations.

i figured what the heck, ill have my tires balanced and rotated, they look a lot better without wheel weights on the outside (i had them put the weights on the inside of the rim only, just for looks) and well, the vibrations are no better and no worse.

i was hoping, but i knew better.

my inner drivers are shot, totally completely shot. the question is, would i get away with doing just the inner driver tripod bearing and of course, fresh grease. or is it likely that i will be just wasting money and time and i should do the driver bearing cups too?

i have heard something about swapping the cups, to reverse where load is applied, thus giving the tripod bearings a smooth surface to apply force to. i thought i had a spare set, then remembered that i put a large flat spot in one on the '86 trans when i was installing it.

i can go parts yard shopping, see what i can find for low mileage engine/trans and take the inner driver cups, or i can swap the cups that are currently in the car. is it recommended that i do anything with the driver cup bearings, might not be a bad idea to replace those, as the spare i have in my garage certainly has a few mm of play in it.

maybe i can get away with just doing the tripod bearings for now, but i fear the cups are so worn that it won't take care of the vibration and i will very soon need new bearings, along with swapping the cups
 
#30 ·
yes, and yes.

though the driver's side driver is off of the seized tranny, in my garage, with, ummm... 215k or so miles on it.

the pass. side driver has ummm... i think 170-180k miles, i cannot recall what the odometer said on the '86 donor car
 
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