I read this in another thread, and didn't want to hijack. Hence this post. (I removed the name from the quoted text because I've been hearing this same statement from many different sources over the years.)
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Check your tranny mounts, if they're broken the car would sway when changing lanes
I've been hearing versions of this since I bought my 88 coupe in 97. I do not understand.
If the cradle is solidly mounted (or as solidly mounted as the pre-88 rubber bushings will allow) and the suspension components are in good condition (i.e., not moving around and changing the alignment) how can motor or tranny mount condition change the way the car steers. The connections between the wheels and the transaxle are CV joints. They really don't care what angle the engine is sitting or twisting, as long as nothing is binding. (If the engine is moving around enough to bind up the CVs, I think you'll have much larger problems to worry about.)
Until proven otherwise, I don't agree.
Can someone please enlighten me?
------------------ Raydar 88 Formula IMSA Fastback. 4.9, NVG T550 Praise the Lowered!
Put a few bowling balls in the trunk, then try a few high speed turns. Your shifting mass. That's what bad tranny and engine mounts will do. If your engine is swinging on bad mounts, your gonna feel it.
I can't go into all of the science that you are asking about, but a few years ago I had a scary experience with bad motor mounts. My 84 started to hit bumps or bridge seams and get loose. It felt like bump steer because the back would go up and wiggle around some, but it aways stayed straight when I held the steering wheel straight and settle back down. It slowly got worse until I drove across a bridge on a highway. The back of the car came up and started bouncing side to side so hard that the back of the car started to come around on me and I had to steer like I was on snow to stop the slide. As the shocks and struts had been on the car for a long time time I got a set of KYB shocks and struts, and took the car to a very trusted shop. I had them install the struts (I did the shocks) and check the suspension out. I didn't tell them what happened because I I thought the new parts would fix the problem. They did the work and called me up to say that if I got the motor mounts replaced I would have a nice handling car. They asked if I had problems with it so I told them what happened and they said they felt the same thing but not as bad as what happened to me. Since the car had close to 200,000 miles I had them do it. The car was so much better and was once again fun to drive.
Sorry to be so long winded but I wanted to explain it as best I could.
Very interesting. My 85 GT has a bad torque strut which I bought but haven't installed. The car wiggles uncomfortably turning at slow speeds and corners very poorly. It also bounces badly over railroad tracks etc. I already ordered Koni's, but I can see the PO had the mounts loose and installed new bolts. Wouldn't it be sad if I spent all that money when it already had new struts? On the other hand my 85 SE has known mount problems so bad I can see and feel the engine move, but handles much better than the GT. The SE has a poly aftermarket torque strut, but the bracket it attaches to the engine through is loose. I haven't been able to get the holes to line up to reinstall missing bolts. I just got the service manual from TFS. In trouble shooting these handling issues it mentions the shocks and struts many times (and also the sway bar, btw), but I don't think it mentions motor mounts. It certainly makes sense that a large mass like the motor could have a major impact on handling if it moved, but even if it did move (which it does to some extent anyway) it wouldn't be much, probably not enough to affect handling. If the engine moves enough to affect handling it's probably about to do something catastrophic imho.
Check your tranny mounts, if they're broken the car would sway when changing lanes
The same way the suspension squats when under load or unloading, it effects the rear camber and suspension geometry. I'm no expert but I broke both my getrag mounts a couple years ago, sheared the brackets, the car was steering from the rear, all over the place on the highway.
Originally posted by rourke_87_T-Top: ...I broke both my getrag mounts a couple years ago, sheared the brackets, the car was steering from the rear, all over the place on the highway.
Now, that I couild see. It sounds like, in that case, the the axles were actually holding up that end of the engine/tranny assembly. I could see how that could put some abnormal deflection on the knuckles. For "just" worn out rubber, maybe not so much, as long as the weight of the engine isn't "leaning" on the axles.
As for the engine just bouncing around, I could see it causing some bumps and thumps, but it seems like the mounts would have to be really fubar for the engine to get up enough momentum to throw off the balance of the car in any appreciable manner.
But it's all good info. Food for thought. Thanks for taking the time, guys.
The only thing I overlooked when I rebuilt the entire suspension front and rear, poly trans, bushings, and/ or aluminum everywhere, Koni, Eibach, etc.
I shoulda known at the time but didn't want to wait for another order from RD, I noticed how thin gauge the original brackets were on the getrag, they became the weak links, the drivetrain was moving around on the tranny side probably only a few inches but it caused a very severe instabilty issue, at first I was unsure what was causing it but after taking a corner quite fast one night on the way to work, I spun the car around in an intersection, I know how to drive my own car as good as anyone, something wasn't right. The drivetrain was probably only moving a "few" inches on the trans side. It felt like the engine was trying to rotate 180*
Okay. Thanks for the info. I have stock brackets on my Getrag, too, but the drivetrain is 5 point mounted to the cradle. I try to keep an eye on those brackets. Give 'em a good look whenever I'm under there.
