TFS Dogbone (Page 1/4)
montegut DEC 25, 11:54 AM
I received The Fiero Store dogbone listed for my 87GT for Christmas and went to install it. The new dogbone is exactly 1 inch shorter then the OEM dogbone. To be installed and used the engine would have to be tilted back the 1 inch. Is this OK? I don’t want to install it if it will put undue stress on the suspension or drivetrain.
cvxjet DEC 25, 12:34 PM
That thing looks way too short.....On my 85, I installed poly bushings on one end to cut back on engine movement, but installed new rubber on the other end so I don't get too much engine vibration transmitted.

Rodney sells an adjustable dog bone...On mine, I noticed that there was a bit of misalignment- I had to always pull the engine back to get the last bolt in- so I installed a 1/8" washer which means the engine mounts are not under a twist-strain all the time. I don't know if that is better but it seems like it would add to longevity....(May-be....)

[This message has been edited by cvxjet (edited 12-25-2019).]

fierofool DEC 25, 07:15 PM
Tim, let me check. I think I have a stock dogbone I'll give you. It will be tomorrow morning before I have a looky-see. I'll give you a call if I do. If I don't call, call me.
fierofool DEC 25, 08:16 PM
Tim, I have 2. Check your email.
montegut DEC 25, 08:20 PM
Thanks Charlie but I don’t NEED a new dogbone. The one I got was a surprise secret Santa gift at our family Christmas party. Everyone at the party thought it was an interesting gift “whatever it does!”
fierofool DEC 25, 09:03 PM
cvxjet, where did you get your poly bushings? I have ProThane bushings in my 86GT but they were installed by a deceased member. I find ProThane 7-501 as the only poly bushings listed for the Fiero. The two 87 dogbones I have are of the type that can be rebushed.
cvxjet DEC 25, 09:13 PM
I believe I bought the bushings from the Fiero Store (But they only fit 85-86)...I installed them at both ends but there was too much vibration transmitted- so I installed rubber at one end- best of both worlds. I have no idea where I got the rubber bushing....This was back around 2003.
Spoon DEC 25, 10:55 PM

quote
Originally posted by montegut:

I received The Fiero Store dogbone listed for my 87GT for Christmas and went to install it. The new dogbone is exactly 1 inch shorter then the OEM dogbone. To be installed and used the engine would have to be tilted back the 1 inch. Is this OK? I don’t want to install it if it will put undue stress on the suspension or drivetrain.



Is that 1 inch from an installed standpoint or an off engine side by side comparison? What condition are your engine / transmission mounts in? If these are anywhere near the condition of your old dog bone your engine is going to be tilted to start with and your going to have to pry it back into position for the bolts to align up. The heavy side of the engine would be the side with the starter, a/c compressor, etc, so it's going to be leaning away from the dog bone with weak mounts.

When I did my 3800sc swap I used new trans/engine mounts and the engine sat level. Connecting the dog bone did not require any prying of the engine to install the dog bone bolts. You may want to check your trans/engine mounts since they could be as old and worn as the old dog bone.

By prying engine to align things up the new bone is going to be stressed from the word go. Its a stabilizer to cushion the engine torque hence intermittent function not constant stress.

Just my 2 cents.

Spoon

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"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

theogre DEC 25, 11:54 PM
Install bones w/ trans in Neutral on level ground w/ wheel block front and back.
This is to unload the drive train so all mounts sees same resting load.

Proper bones don't stress other mounts at rest. 1" bigger/smaller makes a big different to many engines.
Many bone mounts, often on engine side, has slotted holes to allow "free space" to let everything unloaded before tighten the bolts. Many for bone bolt but sometime elsewhere to mount bracket on engine.

"shorter" (or "longer") bones also can mean:
Is really shorter/longer then OE and when you must move engine to install can be problems and break motor/trans mounts.
Already have dead engine/trans mounts and installing this won't help much if does anything at all.
Bone made for different year can be wrong for your year of same car. Carmakers have "rolling changes" and many are not covered the FSM or even most to all Parts Books. Example: Many think all TH125c/3T40 are same but have some to many differences even from one year to the next but only see most if you rebuild them.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

fierofool DEC 26, 08:25 AM

quote
Originally posted by cvxjet:

I believe I bought the bushings from the Fiero Store (But they only fit 85-86)...I installed them at both ends but there was too much vibration transmitted- so I installed rubber at one end- best of both worlds. I have no idea where I got the rubber bushing....This was back around 2003.



Of the two I have, one is in need of bushings, while the other is in perfect condition and the box they are in is marked "85-86 Dogbone. Rebushable". I got them from the same man who rebushed mine. It is exactly like the one I have on my 87 that has the poly bushings on both ends. No noise or vibration.

Think about it. There is no difference in the underlying chassis sheet metal in the 85-87 so the mounts on all should be the same. Even on the 88, the difference in the shock towers and elimination of the trunk blower apparatus doesn't affect the trunk wall to engine spacing. Those TFS bushings should fit all year V6 dogbones.

I have heard but not confrmed that there's a slight difference in length of dogbones and they can be quickly identified by the rib between bushings. One version is smooth, without a rib.