Cascade Crew

Alphius · Posted: Mon Feb 20, 2012 3:48 pm Post subject: Aftermarket Crossmember Problem

Supposedly a cantilevered crossmember mounted torque arm causes some problems with tearing the threads out of the subframe or cracking the subframe. I am looking to get my torque arm off the tailhousing of the transmission and ran across these issues. I don't have the equipment or experience to make my own setup, and I am scared of this happening with an off-the-shelf system.

The torque arm mount being further rearward than the centerline of the bolt holes introduces a lot of twisting of the crossmember, in effect tearing the front bolts downward with a lot of force. The point of rotation as the tq arm pulls upward is the front edge of the crossmember mounts. With a stock tranny mounted torque arm, the point of rotation is the motor mounts which applies a nearly vertical force upwards on all 4 crossmember bolts, avoiding this problem.

Is this something I need to be worried about?
I was thinking of buying this but it exhibits the problem badly:
http://www.hawksthirdgenparts.com/camarofirebirdspohn82-92adjustabletorquearm-700r4t-5transmission.aspx

Twilightoptics · Posted: Mon Feb 20, 2012 4:03 pm Post subject:

No problems with mine.

I utilized all 6 bolt holes though.

Twilightoptics · Posted: Mon Feb 20, 2012 4:04 pm Post subject:

http://www.cascadecrew.org/phpBB2/garage.php?mode=view_gallery_item&image_id=798

Here you can see how far back the torque arm was from the actual bolt holes.

I copied Spohns design really. Used panhard energy suspension bushings and a spherical.

No problems what so ever.

Alphius · Posted: Mon Feb 20, 2012 4:34 pm Post subject:

I would use 6 if I did it too. No reason not to really.

I'm just worried about the cantilever effect but you had more traction with a 9inch and DRs than I would ever have. Laughing

Some people were saying that can happen if there's rot in there, but as you can see in the picture I found there is no rust even in the cracks. The car that picture was from was supposedly a low-mile Formula with street tires and a bolt-on L98.

QwkTrip · Posted: Mon Feb 20, 2012 4:52 pm Post subject:

Check out the Jegster torque arm. It won't use those mounts. It is a short arm so maybe not good choice if you want the car to turn and brake well?
Here is a picture... http://www.thirdgen.org/techboard/ltx-lsx/642183-jegster-torque-arm-fit.html

BMR track pack uses a bar across the car. Not bolt on, but has good reputation for drag racing.

I have a Spohn TKO transmission crossmember and remote torque arm that I will never be able to use. Just sitting on my car in the garage from the day it was new. If you can use it let me know. Shipping cost might be too prohibitive though.

Twilightoptics · Posted: Mon Feb 20, 2012 5:07 pm Post subject:

Spohn's stuff is good contrary to popular TGO bs.

The thing I didn't like about the BMR trak pack is the cross bar seemed to hang pretty low, and you best have SFCs. Exhaust routing can also be a pita.

Alphius · Posted: Mon Feb 20, 2012 5:08 pm Post subject:

I'm not a huge fan of the short style torque arms. I do not know how pronounced the difference is but from what I understand they significantly compromise braking performance (axle hop under hard braking) and cornering.

Maybe the BMR crossmember would work better than the Spohn, it looks like the cantilever distance is a lot less on the BMR style but it's difficult to tell for sure. It also maintains the stock sliding mount instead of the Spohn link which may have a possibility of binding. I could run this with my stock torque arm and then change over to a tubular style later if I have any problems.
http://www.bmrsuspension.com/?page=products&productid=411

Still leaning towards Spohn though.

91RSVert · Posted: Mon Feb 20, 2012 6:55 pm Post subject:

Ive had a spohn in 2 cars for a total of about 7 years. Few things I dont like, but oh well.

1. The front pivot point, if not torqued right, "pops" when taking off fast, or stoping hard. IMO, it should have a brass bushing thats tighter fitting, or some type of ball bearing roller design.

2. The rear part that mounts to the axle. It hits the floor board. Ive hammered that in several times trying to prevent it. If you want pics of this, ive got mycar torn apart and can get them for you.

Ive seen some videos where a camera was mounted under the car, and that the cross member does flex alot even under normal use.

QwkTrip · Posted: Mon Feb 20, 2012 7:09 pm Post subject:

My Spohn arm is the old style with slip connection at the front. One tube slides inside the other and is covered with a rubber boot. You'll never ever find another one that's never been used! It's a collectible. Very Happy

Alphius · Posted: Mon Feb 20, 2012 8:22 pm Post subject:

Twilightoptics · Posted: Mon Feb 20, 2012 9:32 pm Post subject:

I remember schultzy has the POP issue, but no hitting the floor board with his lowered car.

Mine doesn't POP..... Guess I did a good job.

Schultzy89GTA · Posted: Mon Feb 20, 2012 9:35 pm Post subject:

So is my pop because I didn't do a good job? lol

If they are the same design, did you just tighten the pivot more?

Gabe, btw I have had the same setup with the 700R4 and the TKO. Have always used 4 bolts, no problems (so far!).

-Schultzy

Alphius · Posted: Mon Feb 20, 2012 10:00 pm Post subject:

Mike, Paul, thanks for the input.

As you have probably guessed by my recent threads I'm throwing money at my car like it grows on trees. Laughing

The Spohn seems like a good piece, it'll probably be what I run too.

Schultzy89GTA · Posted: Mon Feb 20, 2012 10:04 pm Post subject:

That's the best way to throw it!

-Schultzy

iansane · Posted: Tue Feb 21, 2012 2:14 am Post subject:

4 bolts, no tearing, ~100k miles. I remember reading a few of those threads back in the day, got paranoid and checked my xmember religiously for awhile and now I check it like once a year. Laughing

91RSVert · Posted: Tue Feb 21, 2012 5:03 am Post subject:

Twilightoptics · Posted: Tue Feb 21, 2012 8:46 am Post subject:

91RSVert · Posted: Tue Feb 21, 2012 10:05 am Post subject:

No, the actually body of the torque arm hits. I'll try to rem to get some pics tonight.

91RSVert · Posted: Tue Feb 21, 2012 3:32 pm Post subject:

Twilightoptics · Posted: Tue Feb 21, 2012 3:47 pm Post subject:

Hmm that looks strange. More pictures from farther away.

What is your axle rotation like? aka your lower control arm geometry.