Solid Rubber Trans Mount - 700R4?
 

I’ve completed my 383 swap and torque arm relocation with the UMI cross member. I currently am running “Screaming Chicken” rubber motor mounts and an Energy Suspension trans mount (yes the correct one). I had it with the pre load plate on originally and the vibrations were wicked. Took the plate off and it helped a lot, but im still getting them from 2000-2800 rpm’s lower speed when I get on it.

I read the trans mount comparison thread and almost every other trans mount thread in here. I saw a solid trans mount made by napa that I wanted to pick up, but I guess they’re not available anymore.

is there a durable solid rubber mount that everyone is running in place of going poly? I’m at my wits end fighting these vibrations.

thanks for the help!

Re: Solid Rubber Trans Mount - 700R4?
 

I actually have had complete success for 3 years now with an off the shelf rubber one from Advanced Auto parts.
3 years of lots of abuse

Re: Solid Rubber Trans Mount - 700R4?
 

I also went from a solid intolerable vibration mount to an Advance Auto mount. But that one split. I bought the same one again and stuffed it with the Loctite PL Polyurethane Sealant from Home Depot and its held up well allowing me to burn up the trans....

Re: Solid Rubber Trans Mount - 700R4?
 

just a run of the mill anchor brand one from advance? I’ve heard horror stories on them. I’m not pushing anything crazy. Haven’t did a wheel dyno yet but the motor made 460hp / 480ft/lb at the crank

Re: Solid Rubber Trans Mount - 700R4?
 

You don't want a stiff or strong transmission mount. The trans mount is like a fuse- it will blow when there is some issue with the engine torsion or engine stress related to let you know there is some other issue to take care of.

You want the weakest soft trans mount you can utilize. The place to focus stiff mounting is the engine. Use an engine damper. Or a strap. Use strong mounts. Attach additional mounts. etc...

If you hold the engine properly and prevent it from moving, the energy of vibration diminished will reduce wasted energy and improve the feel of the vehicle driving and shifting.
The engine mount protects the transmission mount.

Re: Solid Rubber Trans Mount - 700R4?
 

That’s really good insight, thanks!

I actually just completed pulling my energy suspension mount off and put on the Duralast solid rubber one. I still have a little bit of vibe, but it feels better. I’m going to chalk it up to not being a hollow rubber one and see if it breaks in with a couple weeks.

Re: Solid Rubber Trans Mount - 700R4?
 

When / If a transmission mount breaks, will it cause a ton of other damage? Can you limp the car home or do you have to get a tow?

Re: Solid Rubber Trans Mount - 700R4?
 

The transmission may buck up but it could be limped home if you go easy on it, your main worry is thrashing the seal at that point. You'll know you broke it when the transmission bucks when shifting into gear and such.

I also don't really buy into getting a weak transmission mount, poly mounts have been around for a while and are in tons of high performance built cars, they aren't going to cause a transmission to blow, if a transmission breaks then it was too weak for what you're using it for anyways. The transmission is aligned to the engine with dowels and bolts, it is as structurally solidified in place as it can get to the engine that's going to hurt it. The output side of the trans is the other possible scenario of hurting it (traction), you would never want sudden and rapid force acting on a loosey goosey just good enough mounted part.

Imagine launching the car and it hooks hard and the trans mount breaks, you now have an unstable drivetrain bouncing around under your car causing all sorts of unnatural shudders and movement. Now imagine you hook with a poly mount, slim chance of it braking, worst that happens is the transmission fails the normal way which rarely ever results in the trans case exploding and is not the fault of the trans mount being too strong. In that scenario the transmission was too weak to handle the power or traction, happens all the time in racing.

Re: Solid Rubber Trans Mount - 700R4?
 

Move the tq arm mount off of the transmission. You'll have to fab something up from the crossmember to make it work.
Then you can use the rubber trans mount with less chance of failure

Re: Solid Rubber Trans Mount - 700R4?
 

In my original post, it says I did the torque arm relocation

Re: Solid Rubber Trans Mount - 700R4?
 

As I mentioned above, I run the rubber one and I run it hard.
at least 100 dragstrip passes in the past 3 years (10 and 11 second timeslips) and plenty dozen autocross events. street miles, burnouts, nitrous launches, all that. motor made 531 hp and 513 torque and I am spraying nitrous as well. This rubber on is fine, but I also spent a whole lot of time dialing in my driveline angles, completely building my own transmission crossmember and also have a relocated torque arm.

Re: Solid Rubber Trans Mount - 700R4?
 

You can drive for a surprisingly long time with a failed transmission mount and not even know it: back when I had my first F-Body ('92 RS/ T5), I noticed that sometimes at lower speeds the gearshifter would move up and down. I didn't think much of it; I just figured it was a quirk of the car, until I was under it one day and saw that the trans mount was completely shot. The up and down movement of the shifter was force from the torque arm pushing the transmission up.

My wife's '89 Firebird had this really noticeable thump/clunk when taking off from a stop; she thought it was the transmission (TH700) going out. Turns out that the mount was completely wasted, and the thump was the housing of the transmission hitting the floor pan!

Re: Solid Rubber Trans Mount - 700R4?
 

Keep it simple...

Re: Solid Rubber Trans Mount - 700R4?
 

im all about keeping it simple lol. It’s just my first build and I want to minimize the chance of failure. I just read so much conflicting info regarding how much a rubber mount can take, people breaking multiple mounts with not much more than a stock motor, etc.

I put the rubber one on, like I said and still have some noticeable vibes through that rpm range. I’m going to check the pinion angle again and if that is fine I’ll try clocking the tq converter