hey everyone i installed a bmr torque arm relocation bracket and the vibrations seems to increase greatly..... before i had a non adjust bmr torque arm with poly bushing, poly tranny mount, and the stock torque arm bracket that attached to the transmission and the vibrations were very minimal.... but when i installed the relocation bracket it vibrates alot more... i have it set at the third hole from the bottom..... it seems like its a very tight fit and the torque arm is very close to the body of the car. even closer than when i had the stock tranny mounted bracket.... what hole should i use... i have a stock height car.... i really like the fact that i moved the torque arm off the tranny... i wanna keep this but the vibrations make me wanna toss it..... if i move it higher than the 3rd hole then the torque arm will rub up against the body of the car..... i need help guys...

 

You probably changed the pinion angle, causing the vibrations. Or, since there is only one bushing to absorb the vibrations now, rather than the two you had before, they are just more noticeable.
Since you can't adjust it any higher, try adjusting it lower and see if it helps.

 

Like Greg said, double check your pinion angle. There might be a very minimal increase because you have the relocation cross member.

 

i dont have a pinion angle finder.... i dont have shims on it anymore and its laying flat where its suppose to...... it just seems like it much closer to the frame of the car.... my interior and everything shakes at certain rpms.... and when i wot the car i get huge vibrations.....

 

The rear of the torque arm is adjustable is it not? That needs to be set. Sounds to me like you did not set it and you have wasted your U-joints. The waa-waa's

I checked on BMR's site what that bracket looks like and that merely is a solid mount crossmember that has front TQarm height adjustment for instant center height. That mount like stated IS solid and will tranmit a little more vibration from the rearend. (Possible you have rear axle bearings going bad also) The mount height of it has nothing to do with major pinion angle. I will only minorly move when you are adjusting IC. I do not know what you mean by shims unless you were shimming up the trans with the old factory x-member. The pinion is adjusted from the rear of the TQarm, not the front mount. Set the front IC height first, then set the pinion angle in the rear.

 

im just going to go with the stock mount.... vetruck do you think i ruined my u joints... i just replace them less than two months ago.... they can actually go bad that quickly just from vibrations... i havent put 100 miles since the vibrations started..

 

It shouldn't ruin your u-joints that fast.

By shims he means shims between the subframe and transmission crossmember, so that the transmission crossmember clears his alston SFC's.

 

Its always possible based on how hard they are driven on in 100 miles and how bad a pinion angle could be. I am just giving you info based on limited knowledge of your cars adjustment specs.

I also noted it could be an axle bearing.

 

hey vetruck

i havent driven it that hard. its actually less than 100 miles.... this is twice i put on this crossmember.... the first time i had to shim up my crossmember to clear the alstons sfcs... the vibrations was bad and after a day of two of that i switched backed to my bmr torque arm with poly bushing, stock tranny torque arm mount and poly tranny mount... everything was smooth again no more vibrations... so i removed alittle bit of my alstons sfcs to make my bmr relocation bracket fit like its suppose to... the second time i put it on all the vibrations came back again..... so that tells me that my rear axle should be fine and my u joints should still be good..... so im just goint to stick with the stock tranny mount bracket..... i dont want to ruin anything so ima just go back...

 

hey vetruck i hear that your a suspension guru so i have a question for you... my car is a high 12 second car at best .. do i really need to worry about the the torque arm mounted to the tranny.. am i making enough power to really need the bmr crossmember... does the stock setup do a good job.... this is my daily driver and will never see the track... its just a fun daily driver..

 

Why not search for/fix the cause of the vibrations instead of just changing the parts that are amplifying it?

 

i get bad vibrations from my UMI tunnel mounted TA, regardless of pinion angle, the UMI TA drops the tranny about 1/2" lower than stock, i shimmed up the tranny/crossmember bushing about 1/2" with steel spacers and the vibrations went away, but it makes the 4th gen Alum DS to rub the top of the DS safety loop, it works with the crappy factory steel DS only.


i think my problem is from the tranny sitting lower then the rear end causing the u joints to be at odd angles in relation to each other

 

You know what is causing the problem, so why not fix it? You can be almost 100% sure that it caused by a change in pinion angle or a problem unrelated to but brought to attention by the aftermarket trans crossmember, which would need to be fixed anyways, even if you can't notice it with the stock trans crossmember installed.

 

The fact that you are even asking the question tells me you are quite content with the factory setup. If it works and does not break then why not keep it if for no other reason you say it seems as good and without the vibration trouble.

What would "I" do? Shagwell gave you the best advice, find the problem of the vibration. I will say a third and last time, I would also check the axle bearings. If it is happening with a solid mount, you are transmitting vibration from the rear rotation assembly somewhere. The two main culprits to focus on first to rule out are the u-joints and the axle bearings. Skipping over them like you think they are fine? then I can not help you any further. They will worsen a vibration under full throttle like you describe. Old worn soft rubber bushings will simply hide a problem that is still there whether you believe us or not. Could be a bad pinion bearing, Its something back there.Heck, it could even be a tranny going bad and you only feel it when mounted solid to the chassis.

Dean.

 

i dont know if you guys know this but my tranny was probuilt less than 2 years ago... the engine has been built by my dad and i(who has been a mechanic and specialize in engine building for 30+ years) from the ground up less than a year ago..... the rear end was checked less than a year ago.. changed fuild and everything.... basically all the drivetrain is new.... the u joints were replaced by my dad and i less than 2 months ago...what im saying is that the reason of the vibrations is that with this crossmember it forces the torque arm MUCH closer to the body of the car where the fuel lines sit... last time i lifted the car you can see where the torque arm was rubbing up against the body of the car because the torque arm rubbed off the undercoating.... i had to move the bracket where the fuel lines are connected to just so the torque arm wont hit it.... but it still hits... that is the problem.. there simply isnt enough room... my question is why is it doing that if i put it in correctly.. its like the crossmember is alittle off and is alittle bit too close to the body side of the car and not next to the transmission side of the car.. and if i put it at the fourth hole as they say then the torque arm becomes wedge inbetween the body of the car and the crossmember... the stock setup did not get near as close to the body as this does and that explains whey when i switched back to the tranny mounted setup all the vibrations went away cause its the torque arm is not rubbing anything... thats why i told you guys i could move it up any further....

 

The tq arm rubbing something does not cause a vibration. It may squeek or pop/bang when it hits, but vibrations are caused by something that is rotating: u-joints, the driveshaft itself, axle bearings, pinion bearings, carrier bearings, the transmission, the converter, the motor, the brake rotors, the wheels/tires, etc. - If the exuast shifted it can also cause a resonance that can be transfered/heard as a vibration type sound.

As Dean noted, the other arm/mounts may be soft enough to mask the issue, but the issue is still there.

Did you change the bearings in the rear or simply "check" them and change the fluid? How old are they, how many miles, etc?

 

oh ok...im not sure if he checked or not but my dad said that everything back there was in excellent condition... i think i can rule out the rear end because if its in park and i dont think neither the drvieshaft or rear end is moving at all and when i rev the engine i also get the very bad vibrations... with the stock crossmember i did not have that issue either...

 

Our transmission mounts and torque arms with built in transmission mounts all keep the transmission in and at the factory location. Are you running a polyurethane transmission mount with this item? If so they do change the height, we have experienced this and read this on a few occasions. We just installed a torque arm with built in transmission mount, LS1 drive shaft using the factory bushing on a 89 and it was nice and centered.

Hope that helps,
Ryan

 

I looked at the BMR crossmember on their website, and it looks like the torque arm can be mounted on either side of the torque arm bracket... did you possibly mount it on the wrong side of the bracket? It sounds like you have it on the body side, and is it supposed to be on transmission side?

 

already tried that and the crossmember is too close to the tranny for the mounting bracket to even fit...... it only fits on the body side..

 

did you contact BMR yet?

 

yeah they just said my pinion angle is off and try different mounting holes... ima just take the crossmember off and use the tranny mounted system... in fact it drove much much better using the tranny mounted system.... i dont even race and its my daily driver so i probably wont take any advantage of it anyway...

 

Hate to say it, but your problem will soon worsen even with the factory mount.Don't know why you are not taking our advice.

My car had solid trans xmember, massive solid heimjoint link to the Tqarm, and a poly trans mount bushing. The only time I had a vibration trouble at all was when my Harmonic balance went bad and it would rattle through the shift console. Other than that one problem I tracked down and fixed when it occured, I never had one bit of vibration through the drivetrain into the shifter console. You could hear the rearend gear noise transmit through the soild TQarm mount, but no vibration.

 

I had such a vibration trouble in my Vetruck I ended up breaking parts.

it was an inherent defect in the design of the truck- A 6ft long drive shaft 1pc design that just would reach critical speed too soon and just stay terrible past 90mph. Factory shaft weht bad and new was discontinued- It was a factory aluminum w/ CF wrap. I tried the cheap steel route, I tried aluminum alone....still trouble. (see pic)
The tounge weight of the driveshaft was too heavy into the tailshaft bushing.

I ended up having to go to an expensive lightweight carbon fiber shaft that weighed 7.8 lbs instead of the 21 lbs the aluminum one weighed or the 28lbs the steel one weighed.. Never had that problem again and it has been smooth as glass clear up over 150mph.

Just two example for you of vibration troubles. They will come around and bit you if you do not fix them.

 

A Bit OT here.

Vetruck, where did you get that CF Driveshaft?

 

I have two of them both from ACPT in Huntington Beach Calif.
The Camaro one was off the shelf 1310 joints and was $795. 4 lb range.

The truck one I had custom made 1350 joints and billet yoke (1350/1350 front, 1350/1330 rear for my Currie 9") Aprox $1400 whensaid and done. It weighs 7.8lbs

Both smooth as glass and noticiable rev increase in rpm range. It upped 2nd gear rpms by about 300 rpms in both vehicles, and got there quicker. Bioth vehicles have majorly built custom 700r4's (not typeical over the couter 700r4's with shiftkits, I mean built with every bell and whistle. Jimmy Gilante of Darryl Youngs Racing Trans was a very good friend of mine for many years while he owned it- He always kept me up with all the latest and greatest tranny mods.

After some major personal life issues are over hopefully soon, I am planning on an immediate install of TCI's new 6-speed auto into the truck with paddle shifters. I can not clarify enough the improtance of a good performance drivetrain other than the motor. I put my money down on tranny, rearend, and driveshft far before I value building a motor.