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Engine strut damper


Richard S

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I should never be allowed to wander aimlessly in the salvage yards, but alas, as I did, I noted that where we have that puny little strut mounted to the the front of the engine and secured to the passenger frame rail near the radiator overflow tank, many other 3.8 applications use a much stouter arrangement. I suspect ours offer marginal resistance after 100k, and wonder if anyone has looked closely at the mounting systems of any other cars to see how much work it would be to switch to something that might actually be capable of doing the assigned task. Wierd, I know, but humor me.

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Guest F14CRAZY

I noticed the same thing...other 3800 cars have a much more substantial mount.

I leave mine off. I don't see what its intention was

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Guest alex_houston

Is it that strut over the harmonic balancer that all years have except the '88s? If the '88s didn't need it, why do the later years need it? Or am I all off on this one?

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I susptect it may have been added after 88 because there was excessive wear to the motor mounts and engineering thought the additional stabilization would help. However, that fails to explain why so many other cars with the same motor were engineered with so much more significant a system. Maybe the strut bears some relation to the weight of the vehicle?

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Guest F14CRAZY

I actually didn't blow the tranny. My performance loss was due to the harmonic balancer/crankshaft key and keyway being F-ed up, which threw off the CPS readings.

I bought a new one in like 2005 from the dealer, but I don't see a tiny little shock is going to do much of anything

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Guest imported_REATAMANZ

The motor mounts transmission mounts actually serve many purposes other than to hold the engine and tranny in place. They do as stated retard torque, but also are designed to reduce vibration and noise. You may have seen torque struts that have a large hunk of alum or casting that looks like "why would they do that". The car engineers when they finally get to a prototype car build find out the engine, tranny vibrates makes noise etc. The engineers then modify the mount. If a hydraulic mount they would change the orifice plate inside the mount to either increase or decrease the flow of fluid from one cavity to another. "which is actually antifreeze with some other ingredients" If a torque, vibration or noise issue was present they would redesign the strut with more strength or add material. It's really more complicated that it appears when you look at the parts.

One of the future technologies that will becoming down the road is real time feed back for mounts using sensors. It will use the same type technology that the Corvette uses in their suspension. "Real Time" damping.

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I have an '88 model that doesn't have the strut on the front of the motor as referenced above.

Since I got the car, it's had a noise at idle that is like a deep thumping sound that can barely be heard inside or outside the car, almost like a burned valve sounds. I have not been able to pinpoint the sound for certain. With a stethoscope the sound seems to be loudest at the mount that is toward the front of the car and at the AC compressor clutch shaft (even with the belt off). I have checked everything I know of; compression, timing chain slack, installed new harmonic balancer and everything else I could think of.

Maybe the noise I have is the reason for the strut being added to the front of the motor on later models. Do other '88 model owner have a similar noise to the one I describe?

Maybe adding the front strut would help with the noise I problem have.

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Guest ChevroletR

I also have an 88 that I don't believe has what you're describing, but I'm pretty sure I know from working on other GMs at the dealer what you're talking about. Is it like a little lift support for a hood or trunk? Maybe gas charged? Pictures?

Ryan

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Guest ChevroletR

No, I can't say I've had a "thumping" noise, however, I did have to replace the timing chain and tensioner because the engine would have a clacking noise and it came to find out that the plastic on the tensioner was gone so the metal tensioner was against the metal timing chain. But I saw you said you checked timing chain slack...did you happen to look at the tensioner?

Ryan

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No, I checked the slack by turning the balancer by hand and watching a rocker arm to see when it moved. It could possibly be the tensioner making the noise. I may check that this winter when I stop driving the Reatta. Thanks for the tip.

The noise is only there when the car is idling. As soon as I increase the rpm the noise goes away. I've run myself nuts looking for it.

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Guest ChevroletR

Yeah, that last part where you said it only does it when idling makes the timing chain tensioner a little weird to be the culprit. Still possible though, because maybe other engine noise can be covering up a little click at higher RPMs. I would check there with your stethoscope though. Good Luck

Ryan

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Guest MauiWowee

If I wanted to check that piece, I would get someone else to put the car in gear, mash on the brake, and press on the gas. If it is not functioning as designed, the motor should twist as Jon described. No foolin'

cool.gif

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That will certainly test the motor mounts and the top wishbone mount, but I'm not so sure about the damper. When you give the car gas, the torque wants to twist the motor clockwise [as seen from the driver's side]. Looks like the damper would only affect up and down motion of the front of the engine. Since the wishbone mount on the right side of the motor probably stabilized that side, maybe Reatta engineers decided that under certain circumstances the left [front] side of the motor had a bit too much "play" on severe bumps. Amazing that in 1990 they were able to foresee the advent of the near vertical suspension-killing speed bumps making their appearance in the nation's parking lots.

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  • 16 years later...

My 90 has the lower mount for the engine damper but the upper mount is missing. Now that I have a new Mercedes/Reatta strut, I'd like to mount it.  I'm assuming it is bolted on not welded.  Anyone with a parts car have the upper mount?

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Just my $.02 but I have been leaving that mount off altogether and haven’t noticed any downside to doing so. The 88’s didn’t have it from the factory but they also didn’t have that cage style thing on the flywheel end either, so perhaps they are some form of package? 

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As 2seater knows I have replaced the engine in my 1989 Reatta with a 1988. I left mine off as well because now it's an 88 setup. Makes swapping the serpentine belt a whole lot easier.

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  • 1 month later...

Well I have the upper and lower mounts and the strut, but I'm not sure how the thing actually sets up.  I am assuming it uses washers and probably a rubber cushion but I couldn't find an illustration in the FSM.  Anyone know the specifics?

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Can't tell you as I have had mine out for 7 years. At that time I bought and installed a different block [88] which that year didn't use it. One advantage of not having that strut in place is that swapping the serpentine belt a lot easier. 

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It mounts top and bottom like an old style sway bar end link. Rubber cushion and washer on both sides of each end.

 

I agree with Dave. My boys and I have three cars, one each of 88 through 90, and none of them have that little shock in place, nor the brackets.

 

 

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I suspect those torque dampers are of minimal effect but since I have most of the components, I figured I'd see if I could replicate the original.  GMPartsGiant.com has the upper cushion but they want $13 + shipping for each.  The lower is out of production.  If I can't find suitable substitutes, I suppose I'll remove the mounts and go commando.

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2 hours ago, minor4326 said:

Funny how some cars use a solid piece and Reatta uses a shock.

I have a Ford Ranger from last century, 4.0 liter V6 which also has a similar shock type setup. It isn't as centered relative to the crankshaft, but it is RWD as well? It has some sort of flex mounted weights on the rear of the transfer case also. My assumption it is all for NVH reduction. Noise, vibration, harshness?

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That picture is very helpful, 2Seater.  Thank you.  The cushions on the bottom mount look like standard sway bar bushings?  They look different and smaller than the bushings at the top mount?

Jonlabree, may I ask where you got the strut tower brace from?  The convertibles can use all the additional rigidity they can get .

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