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1968 AMX Front Trunnion Elimination

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husker View Drop Down
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    Posted: Jan/09/2013 at 9:53pm
Are there any alternatives to eliminate the trunnions on a '68 AMX?
 
I am aware of the Control Freak set up but not looking to spend that kind of $.  I was hoping for more of a bolt in using later model parts.
 
Will the upper control arms and spindle/upright from a later car fit in a '68-9 AMX?  If so has anybody tried this?
 
My thougt would be to modify or fab a new upper control arm to accept a coil-over similar to the WSC kit for '70-up cars.  Or just use that kit for that matter.
 
Thanks
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amx39068 Quote  Post ReplyReply Direct Link To This Post Posted: Jan/09/2013 at 10:39pm
Control Freak is the best option that I am aware of. Other's provide alternatives but are not the size and breadth of Control Freak.
Dan Curtis, AZ AMC Collector Quality Restorations & Parts - amcmusclecars.com
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348AMX View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 348AMX Quote  Post ReplyReply Direct Link To This Post Posted: Jan/09/2013 at 10:48pm
I agree^^^, the trunnion suspension is a good setup when in good condition and maintained properly.
But if you want to upgrade then I would save up and get the control freak set-up, its a really nice package, and a LOT of muscle car enthisiasts across all brands are using it.

The fact that they even made it available at all for AMX's is reason enough to support them and purchase their products. It will make an AMX handle amazing.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote husker Quote  Post ReplyReply Direct Link To This Post Posted: Jan/09/2013 at 11:08pm

I agree that the Control Freak stuff is really nice but it is just cost prohibitive for me right now. 

 
Anybody know about the upper control arm/knuckle interchange between a 1968 amx and something from the 70's or 80's?  Hornet, Grem, Concord, etc.....
 
Thanks
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote purple72Gremlin Quote  Post ReplyReply Direct Link To This Post Posted: Jan/10/2013 at 12:41am
If you want improved geometry, go control freak. otherwise leave it stock.

Edited by purple72Gremlin - Jan/10/2013 at 12:42am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote uncljohn Quote  Post ReplyReply Direct Link To This Post Posted: Jan/10/2013 at 5:42am
The upper control arm from 70+ AMC will not fit your 69 and down car. You are pretty much stuck with a trunnion and the suspension as AMC designed it.
The best that can be said is when in good shape it works. Past that I can think of no reason to keep it except the expense of replacing it.
I am aware in the past of effort to design something to replace things with at this point in time have no idea where they went.  The price of the control freak suspension is not only typical of the genre but the components are too. 
I am aware of some conversions done where the entire spring housing has been cut out of the inner fender well and then a 70 and up front suspension and spring housing has been installed. It takes a fair amount of work to do it and a passably good fabricator to pull it off. If you are that good it is reasonable way to go. If not? Then the alternative is still the control freak or maybe others too. Or be good at rebuilding your trunnions or having it done for you.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote amx39068 Quote  Post ReplyReply Direct Link To This Post Posted: Jan/10/2013 at 8:59am
Originally posted by husker husker wrote:

I agree that the Control Freak stuff is really nice but it is just cost prohibitive for me

Anybody know about the upper control arm/knuckle interchange between a 1968 amx and something from the 70's or 80's?  Hornet, Grem, Concord, etc.....

Thanks

 


Freshly rebuilt trunnions work perfectly fine in our pre-70 cars. You will need a thrust bearing with a 1" ID and ACE hardware has the mylar washers and o-rings required to rebuild the trunnions. The AMC vendors and other here on the forum have urethane horizontal bushings needed for the trunnions and urethane providers have the vertical bushing that goes over the steering knuckle end inside the trunnion as well. The 70 and up ball joint can be used on the control arm by drilling two new holes for the rear bolts and both the original style rubber bushings or urethane bushings are available for the rest of the front end.

The only time you cannot rebuilt the trunnion is when the hole for the steering knuckle has eggshape wear. When that happens the trunnion is no longer rebuildable and either needs to be sleeved or tossed in the trash.

Properly lubricated and installed urethane bushing kits will bring the car closer to the ride and handling of a more modern car and the Control Freak style front end will make your old AMC totally feel like a modern engineered car. With either option, it is highly recommended that you use radial tires due to without them, the car will ride like a cement truck on factory correct bias ply tires in combination with urethane bushings.

We put urethane suspension parts in all the cars we restore and would not consider using anything else. Others dislike the urethane bushings claiming they make the ride too harsh. My first hand experience is that with urethane bushings along with KYB gas adjust shocks on good quality radial tires our cars feel far more like a tight modern suspension engineered car than the wallowing and wandering vehicles that were so common in the 50s through the 70s. Others may disagree buy anyone who drives my cars, including hard core proponents of urethane bushings, all agree that they are great driving cars.

Edited by amx39068 - Jan/10/2013 at 9:01am
Dan Curtis, AZ AMC Collector Quality Restorations & Parts - amcmusclecars.com
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bigbadgreen Quote  Post ReplyReply Direct Link To This Post Posted: Jan/10/2013 at 9:33am
Any problems with urethane being too squeaky?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amx39068 Quote  Post ReplyReply Direct Link To This Post Posted: Jan/10/2013 at 9:38am
only if you fail to use enough of the grease they give you. One car has a initial squeak that goes away with 2 minutes of driving but I believe it is in the strut rod bushing that was replaced before we got the car so it will be taken apart and properly greased and that will be the end of the squeak.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote uncljohn Quote  Post ReplyReply Direct Link To This Post Posted: Jan/10/2013 at 10:17am
The use of rubber in the upper and lower, especially the lower control arm allows the movement of the arm to flex at the bushing. Urethane does not flex. When installed it must rotate rather than flex. Rubber is vulcanized to the inner and outer shell, the urethane bushing must rotate with in the inner and outer shell.  Long term driving causes excessive wear of the bushing due to the rotation. Also the lower control arm due to the dynamics of the strut rod and the single point mounting goes through a monkey motion movement due to the dynamics. This also requires the flex of the lower control  arm bushing to allow that movement with out stressing the mounting point of the bushing used at the point of rotation, that of the engine cross member.
Radial tires require an alignment setting of positive caster. About 1 or 1 1/2 degrees. The AMC front end follows design featured by the use of non-power steering, that of negative caster which favors steering input assistance to for non-power. That is as the car turns the weight transfer during turning helps turn the steering wheel. This also causes wander for short wheel base cars such as the AMX, Gremlin and Spirits and anything else but quite obvious in short wheel base. As Power steering steadily became factory standard, front suspensions were designed to favor Positive Caster which self aligns going straight ahead but makes it harder to turn the steering wheel.
Bias tires had a fair amount of slde slip, radials do not and AMC never re-designed their front suspension to favor modern technology. In fact Bias tires were still pretty much standard almost to the end of production including bias belted.
There is about enough room to dial in up to3 degrees of positive caster but doing so greatly increases the monkey motion of the lower control arm. If the bushing does not flex the control arm will thus stress the mounting point woggling out the bushing mounting hole due to stress and inducing cracks into it.
Re-enforcing it is not the answer, it is designed to flex, all re-enforcing does is aggravate the fatigue factor.  Long term is excessive wear of the bushing, lower control arm and damage.  Unless rubber is used.
If the car is not driven it makes no difference, a show car looks good. On the show car circuit in the automotive hobby many of them have never run much less had lubricant in them.
A common fix for a woggled out lower control arm bushing being loose on install is to tack weld the bushing in place. As the urethane bushing must rotate, think what tack welding does.
So no, I don't use urethane when I rebuild a front suspension. I use rubber on the bushings. Not only does it ride like a truck almost no matter what tires are used and driving one any distance these days on anyting other than good radials is a bit silly. My Spirit uses p235 60 14's in front, P245 60 14's in back, tracks straight down the road at speed and has about 45,000 miles on it now. That would not be a comfortable ride on Bias Ply Tires. All my AMC cars run radials and rubber replacement bushings.
In you have no choice, use urethane. That is what they are their for. I made my own sway bar mountings out of urethane for the 1980 AMX I did. They do not make rubber ones that big for that car. At the time it was rebuilt. 
But for a long term safe driver?
Rubber works, reduces wear and is not as harsh on the lower control arm when set to reflect Radial Tire favored specifications.
I've rebuilt some 2 dozen front suspensions and still have a stock of spares on the shelf and have become quite adept at reconditioning lower control arms.
Yes I agree, an AMC car with urethane handles well. Nothing moves, it should. But then again if it was re-bushed with OAK it would handle well too. It just would not last very long.

70 390 5spd Donohue
74 Hornet In restoration
76 Hornet, 5.7L Mercury Marine Power
80 Fuel Injected I6 Spirit
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