I've seen a few people mention it here before but never seen much of a solution.
I have the rod end arm that connects to the separate mount on the T56 cross member. It bangs up and down when ever there is not a constant load on the torque arm. Well, since I had the stuff out anyway to rebuild the T56 I decided it was time to fix that.

The problem is not the rod end, but the other pivot point. The bolt that is used is not really the right one. The shank doesn't go all the way through and the threaded diameter is smaller causing slop on the one side. The bolt has some lovely flat spots on the threads from being banged inside the mount.

Step one was buy a longer bolt. Long enough to where the shank went all the way through as the same diameter. Then machined the extra unneeded portion of the threads off to make the bolt the same length as the original. This alone would have likely been enough, however it was taken a step further.

The whole crossmember was put into a milling machine and the mount hole was drilled and reamed to 1". After that a bushing made made to just slide inside, and the bolt fits inside that. Everything is made to just slip in nicely with no play. It's still greaseable.

Now there is ZERO slop. Before you could hold the pivot joint and pull it back and forth clicking it which when under the force of the torque arm is a nasty banging. It still pivots like it needs to and should make no noise what so ever.
I can't wait to get it all back together.

 

do you have any pics of the process you went about doing? im going to be purchasing a tranny mounted TA and don't any noise.

 

No sorry. I basically handed the mount to my brother in law and told him what I needed. He took it in to work and the CNC guy there did it.

The trans mounted torque arm won't make any noise. It really only effects the ones with the cross member mount.

 

Jay,
This sounds reasonable. I wouldnt have thought thats where the noise was coming from. I thought most of it was coming from the rod ends at the rear of the arm. The ones where the adjustments are made... Those seem to have slop in them as well. The darn rod ends can move on teh bolts. Thats really annoying for what I spent for the thing...

Anyway... I like your idea here... Only problem is I dont have acess to machine equiptment to mess with the bolts and all. But just so Im on the same page with ya...You got a longer bolt, with a longer shank to it. Then machined threads into the shank so you could tighten the nut down... right?

Or were you able to find a bolt with a smooth shank that was the right length. If this is the case, I might be in good shape to try it. I still wont be able to make a bushing, but that shouldnt matter.

How close are you to having it back together to try this out??? Im really curious to see if it fixed your problem.

J.

 

i was planning on buying the crossmember mounted TA is what i meant, i was pretty tired when i posted, sorry for the confusion.

 

I can post some pics of what I have now to show it a little better and try and explain it. Have to do it later tonight after I get off work.

As for the bolt it was just a matter of getting a longer grade 8 bolt, basically the same thing as came with the torque arm, just with the bolt being long enough to where the shank was the full width of the mount. I'm not sure what the overall length ended up at since I didn't buy the bolt, but I can ask my brother in law. He just cut the extra threads off to make the new bolt the same length as the old. He used a lathe to cut it since they had it but using a hack saw or cut off wheel and a nice straight cut should be fine. They didn't need to machine any new threads.

As for getting it back together.. I'm trying lol. It was one of those things that snowballed out of control. So along with rebuilding the T56, I upgraded the differential to a TruTrac, brand new brakes front and rear, new front springs ( found a broken one while doing other stuff ) waiting on some parts to come in later this week to put the all new steering in. I'm hoping weekend after next to have it where I can test drive it at least.

 

Definitly post up some pictures.

In another thread people say "just tighten down the nut" but I tightened the living crap out of mine and it went back to clunking after my first downshift :-(

 

Bolts that you buy from most suppliers are pretty standard. All the grade 8's I've seen have 1" of threaded length (if the bolt is less than 1" then the entire length is threaded) and the remainder is unthreaded. Anything aside of that is unusual. There are bolts with the entire length threaded (a little more unusual), but something other than 1" of threads is going to be near impossible to find. I would advise not using a fully threaded bolt for the reasons mentioned above. From Spohn's site it looks like there is a mounting ear on the crossmember, and two plates (possibly part of a single piece) on either side. If there's a bolt available that matches that assembled length (plate-ear-plate) then you're lucky and someone should post up that dimension. It may be that a washer or two would be required to get the right spacing and be able to tighten the connection properly.

FYI having a connection like that with threads either on part or all of that connection is bad enough to reduce the intended strength of the connection on the order of 50-60% so thats why you're getting noise. This is no guess either, its exactly how a model steel bridge at my college for an ASCE (American Society of Civil Engineers) competition failed (excessive deflection). It was tested in practice and later in the lab correcting the connection and measuring the loading on the connection and adjoining parts to the point of failure in both cases. Dont be worried about the connection failing though its not going to get to that point on this part (its going to fail elsewhere first) but the play is there and that excess deflection is, in this application, more of an annoyance than anything else.

 

Ok I have some pics, not sure how much help it will be.

First a comparison of the bolts. Basically you need the non threaded portion to be long enough to go from one end to the other, with the threads just stopping at the edge of the plate that connects to the upper rod end connection. To be honest, mine is still just slightly too short and the plate on the side with the nut still has some threads in it. I'm going to buy a longer bolt, another 1/8" to 1/4" length should do it, and as madmax suggested may require a washer to fully tighten.


Here's a picture of the bushing. It probably wasn't completely necessary as it seems the original bolt had started to wear and actualy fits inside the bushing with more slop compared to the new bolt. There's no real point to the grease fitting anymore since the bolt no longer moves on my assembly. It's that tight of a fit in the bushing.



Then one more of the thing back together.


While I can't say for sure that this will solve the problem, I can say that it fixed they way it was. Before I could take the two parts and pull them away from each other and could hear a clicking, feel a lot of looseness and see the bolt moving inside the ear and plates. Now it won't move at all.

When I get the slightly longer bolt I'll update and post the length I used.

The rod ends on the adjustment side do have play in them as well... more than I would like also. I'm wondering if it's a similar situation with the threads being in part of the ID of the rod end. Thing with that side is, you should be able to tighten them up a lot once the adjustment is made and keep them from moving. They don't need to rotate once the adjustment is made. I don't think the noise is coming from there, at least not mine anyway. Due to the leverage at the front of the torque arm there is a lot more force which was causing it to slam hard inside that mount. You really can't tighten that bottom bolt up too much because it HAS to be free to move and let the assembly pivot front and back. The top one with the rod end you can tighten up since it will rotate freely on the rod end.

If there's any other questions or comments.. post them

 

Hmm... Ill have to go bolt searching once I take mine apart again. Im curious if this solves it. My clunk seems much heavier though...like it couldnt be caused by just the tiny bit of slop in that lower bolt. Mine sounds like something is allowing the rear to rotate and cause a clunk.

Im not sure if its just driveline slop? But when the rear is out, Im going to check the set up of the gears to make sure everything is ok. Also, this is my first manual trans car...so I might be hearing normal things under normal conditions. Just since everything on my car is poly or solid...it transfers the sound more.

Anyway... I still like this idea, and Ill probably go over the entire torque arm and try to apply it to the rear bolts as well. The other thing I want to do is make sure Im not getting movement at the torque arm bracket on the axle housing itself. Those two long bolts never seem to tighten up enough, and I even got the longer ones from spohn. Ill figure out a solution for that...even if it means ordering even longer bolts and double nutting it.

Good info and thanks for the pics! Good to know you dont NEED a lathe to try this fix.


Justin

 

Hmmm,could this be the cure to my 700r4 spohn tq arm clunk?

 

TTT- any luck fixing the clunk OP? I've grown to live with mine but it is still annoying.

 

Im gone try replacing just the bolt(bolts),I have the bushing ends,so Ill pull both bolts and see whats up(top bottom),and inspect the rear bolts has well. thx for the excellent advice!

 

I drove the car last season with many trips to the track and it has not made ANY noise or clunking what so ever since the fix.