Just needed some info on a new tranny mount. I have a 99TA with M6.

Energy Suspension

Prothane

Are these just standard GM trans mounts?

When using one of these 2 do you lose the failsafe locking design of the factory mount? These units are shaped differently.

If these are the right ones, how do you bolt the mount to the crossmember as there is no central stud?

Is the center hole tapped for threads and you run a bolt from underneath?

Is there a preference between the two brands?

 

I just installed a Prothane last week.

It comes with a threaded stud that you must "double-nut" to tighten into the bushing and it has three threaded holes in the bushing(1 for one bolt design and the other 2 for the two bolt design). Once you thread the stud into the mount, you put a bolt on from underneath like stock. I dont know what you mean by the "failsafe locking design" but thats definitely the mount that I installed.

I had heard that Prothane was really rough, and after I installed it there was a ******* earthquake underneath my car at 2000rpm to redline, also at speeds of 65-80mph. Im telling you, IT WAS BAD.

After a 1000mile trip to Lake Tahoe and back, some city driving and some street racing its gotten better, but it still vibrates at freeway speeds.

Ive heard that Energy is slightly softer but I havent experienced one.

 

The failsafe design on my mount has metal ears and a metal tab that mesh together. On my mount, the rubber is completely ripped in two but the tranny was not bumping the tunnel like a lot of folks said it would. Anyway I think it is a moot point, when looking for a picture I found a cutaway of the ES mount.

It shows the threads I wasn't sure about as well as an internal failsafe design. If the poly ever breaks the metal tabs INSIDE will contact and limit movement.

'02 WS6, if it is so bad why not replace it with a rubber one?
Does it at least feel better from a performance standpoint?

 

If its not messing the car up I can live with the vibration, it definitely feels much better when I bang gears though, not near as much lash in the drivetrain.

 

Leave of the preload spacer and you won't get any of the vibrations or noise.

 

I just bought the tranny mount. The ES one.

After doing some more reading I'm probably going to grind off the bumps and leave that plate off. If the new mount is still taller than the original, I bought 8 thin rubber washers and 4 thin metal washers. I will place 2 rubber washer on each bolt between the crossmember and body. If the crossmember needs to be spaced down some more to retain the stock driveshaft angle I will add the metal washers to the rubber ones.

I know the poly bushing by itself is going to be stiffer than the rubber one, so why would I not do everything I can to soak up any vibrations?

I will be replacing the TA bushing pretty soon when I can find one.

 

yes....the T-56 takes the standard old GM trans mount (that’s one nice thing about GM....they seem to make a lot of things cross-connect).

I have had one Energy Suspension and one Prothane trans mounts in my car to date. I put the ES one in about 3 months after I got my car and yes, the vibration is slightly more than stock but insignificant if you ask me (personally I laugh when I hear people whine about vibration in a performance oriented car........if you want a Cadillac, buy a Cadillac ). That was 4 years and 50K miles ago. When I did my motor swap I noticed that the poly had some small cracks starting to form in places so I felt "since the transmission is out anyways.....whats $20 so I don't have to play with it again." This last time I put a Prothane mount in because thats what a local place had in stock. To me, Poly is Poly......whatever you can get your hands on/find the best deal on will work fine....

you will reuse the stock bolt to connect the poly mount to the transmission......then buy a standard Grade 8 bolt (I think it's 5/16-24) from ACE to bolt the poly mount to the transmission crossmember.

 

I was planning on using one of the 2 bolts that came with the mount. Since the center hole is threaded I was just going to run the bolt stright up and use a lock washer on it.

Do you really need a different bolt? I wouldn't think so.

 

depends if they are the right size or not........

 

I plan to use the 2 factory bolts that go into the trans. The mount has a flat tab on either end with a hole in it, so the factory bolts will work just fine for that.

The center hole in the trans mount is threaded and the mount comes with 2 bolts. The bolts do thread into all 3 holes, so I think the ES bolt will work just fine as long as it is long enough and I think it is.

 

Well I got my ES tranny mount on. The old one was torn into 2 pieces. The "safety interlock" built into the stock mount was preventing the tranny from really slamming the tunnel. I ground down the 2 bumps and left off the preload spacer. Both made sense once I got under there and looked at everything. I used 2 rubber washers per crossmember bolt as well. Still using the rubber TA bushing. I can barely hear a difference at all. Even with the windows up and exhaust cutout closed there is just a tiny bit more sound. I don't think I can feel any additional vibrations at all. I must have done something right. Once I add the poly TA bushing I doubt there will be much increase in noise or vibration. There might be a little, but I've also heard that the tranny mount will quiet down after a week or so of driving so I'm not expecting much additional noise if at all. With the windows down or the radio on you can only feel the lack of slack. No way can I hear additional noise.

I do notice that the tranny is a bit higher so I will probably drop the crossmember when I replace my TA bushing and put a total of 3-4 rubber washers as well as maybe 2 thin washers per bolt. That should drop the tranny just a little to where it should be as well as add a little more cushioning.

The shifter feel is much improved. I run the Hurst Billet Pro and it does feel better. I still get some engine torque which can move the **** maybe 3/4" under throttle. I plan on swapping the drivers side engine mount with poly soon.

So for those who want to run the ES tranny mount, leave off the preload spacer, grind off the 2 bumps on the bottom and figure adding 1/4" worth of washers to space the crossmember down.

I'm going to use a combination of metal and rubber washers to get my 1/4" or so of space.

I'd recommend this mount to everyone who has a manual tranny.

 

I never had to space my crossmember down........fit like it was from the factory.......

when you do the motor mounts, do both.........

 

If your not getting a lot of vibration then I wouldn't bother to space it down. Mine isn't spaced down much as the rubber washers compressed pretty far and mine is quiet.

I was mainly suggesting that to '02 WS6 and possibly other Prothane users. I'd rather have some washers handy for the install in case I needed them than not have them and end up with the tranny touching the floorboard. You know what I mean?

In theory that would be best, but I've heard, and it appears to be true, that the passenger side is extremely difficult to get to and change out. Some have to pull the compressor down, remove starter, etc... In all actuality, the left/drivers side is the one that flexes the most and would be the main one to change. It's also the easiest to get to. Then if you want to tackle the right side, go ahead. I think I would just do the left side and see how it feels.

They even sell the motor mounts individualy so changing one side only makes good fiscal sense. I've heard a lot of folks change only the left with good results. That's my reasoning for doing only that side.

 

oh ok......guess I was lucky with mine....it just slipped right in (well...not "slipped" but went in ok)....

I don't remember one being really any harder to change than the other (though that was almost 2 years ago).......the engine still torqued over even with both done (really need a torque strap) so I couldn't imagine only doing one.......

 

The engine still torqued over? Sounds about right in your car. I'm running a lot less power, stock in fact. I don't drag race either. Mine is more of a road race daily driver.

I've heard of people using metal stock shaped mounts, but combined with tlots of power it may distort the block or even break it after a while.

I wonder, in my case, if a solid motor mount on the drivers side would be fine for the engine? It would still have some flex from the right side mount so maybe I should took into those.

As you can tell, I don't know much about the mounts, poly or solid, for these cars and all the little tricks associated with them. I think I have a pretty good bead on the tranny mounts.

If you have some suggestions on solid motor mounts, let me know. I want to get rid of the shifter movement under acceleration. There have been times in the past where it torqued to the point 1st gear was almost where 3rd gear should have been. Getting rid of the play would allow me to shift with more confidence, I'm sure.

 

I made a new post with more details of my install.

https://ls1tech.com/forums/showthrea...86#post3333486