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Transmission Mount Tech

[memphis]

Web wheeler
Joined
Jun 6, 2020
Member Number
1867
Messages
747
Searching old threads more so on the old site… a lot of people say the mount should be triangulated with the engine mounts and to use the same material

I inherited a TMR transmission crossmember mount in a part out which uses poly bushings at the frame and a hard fixed centred mount

Is there any reason I couldn’t use a poly mount on the transmission still and keep the outer poly bushings on the frame side?

I was just rewatching Fred’s 4L80e maintenance video on the summer camp Jeep and it appears that his transmission crossmember is set up like my question

Poly doesn’t really move that much… this would make for a pretty clean flat belly install as well
 
If the whole crossmember is mounted to the frame on poly, I'm not sure I see an advantage to also mounting the trans to poly and then to that same crossmember....if I'm understanding you correctly.
 
Sean said:
If the whole crossmember is mounted to the frame on poly, I'm not sure I see an advantage to also mounting the trans to poly and then to that same crossmember....if I'm understanding you correctly.
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You are understanding what I asked. Basically I have the trans crossmember already… it just feels wrong hard mounting the trans with the bushings out at the frame
 
What are your engine mounts made from?

You could poly the trans mount and then get hard poly bushings from AutoFab for the frame ends of the x-member.
 
Everything needs to have the same range of motion. So hard trans mount and soft engine mounts will stress things. The setup you have is fairly rigid. It will likely stress the bolts where the xmember attaches to the trans unless the engine mounts are also hard.
 
gt1guy said:
What are your engine mounts made from?

You could poly the trans mount and then get hard poly bushings from AutoFab for the frame ends of the x-member.
Click to expand...
I was planning on poly engine mounts once I settled on a poly trans mount. I bought a CJ7/TH400 style mount in case I decided to switch out for rubber on the transmission side if the vibes are too much from poly engine mounts
 
I tend to use regular old (IIRC) 1.5" graphite impregnated poly bushings that take a 1/2" bolt and fit inside 1.75"x.120 wall tubing on engine and transmission mounts....although a lot of buggy guys are just hard mounting them now. On a street driven vehicle, I wouldn't consider it, but might on the next buggy.
 
Any leads on a universal tube style rubber bushing that would mount in a similar fashion to the standard poly ones? I'm trying to reduce vibrations on a new build as the poly transmits too much noise from experience.
 
Bushings at the framerails and center of cross member was good enough for a fordfuckinranger!

:homer:
 
Thatg9659 said:
Bushings at the framerails and center of cross member was good enough for a fordfuckinranger!

:homer:
Click to expand...
They didn't have the bushings at the ends of the cross-member for the first 20yr. Rangers got them sometime in the 90s. Aerostar had the bushings on the crossmember from the get go. I suspect it's an NVH thing.
 
arse_sidewards said:
They didn't have the bushings at the ends of the cross-member for the first 20yr. Rangers got them sometime in the 90s. Aerostar had the bushings on the crossmember from the get go. I suspect it's an NVH thing.
Click to expand...

You’re talking sidewards out your arse again. :flipoff2:

In my experience The triple bushing crossmember started in 85 then left sometime in the 90’s Xmembers before and after were hard frame mounted with single bushing under the trans.

I prefer the 84 4x4 style, had to use that one for front shaft clearance when I installed the doubler.
 
Thatg9659 said:
You’re talking sidewards out your arse again. :flipoff2:

In my experience The triple bushing crossmember started in 85 then left sometime in the 90’s Xmembers before and after were hard frame mounted with single bushing under the trans.

I prefer the 84 4x4 style, had to use that one for front shaft clearance when I installed the doubler.
Click to expand...
You're sounding like a POS Commiefornian carpetbagger (pick your favorite flavor :flipoff2:) nit picking because you just can't let anything I say go unchallenged :flipoff2:

Here's a '94. Every Bronco 2 I've seen (so 2, lol) has been the same (and I wish it wasn't because it would've made it way easier to pull the trans at the junkyard and then stuff it into the receiving vehicle). And I can tell you that a '92 2.3 5spd. 2wd has a hard mounted crossmember too so it's not just a 2wd 2.3 5spd thing

attachment(302).jpg


And here's the late model year '95, 2.3, 2wd, 5spd that engine you need to pick up is out of.

attachment(301).jpg

My Aerostars have the same looking thing but I haven't measured so IDK if it is actually the same.

Regardless clearly it wasn't a short lived 80s thing. They were doing that shit in the tail end of the TTB years too.
 
Last edited:
I run two poly mounts in dom tubing on the engine. Mounted parallel to the valve covers. Then run two off of the trans. I also run two mounts at the very rear of my nwf/205 doubler set up. All tube mounts parallel to the engine/trans. Super rigid setup but I like it. Only vibrates noticeably above 3000 rpm on the road. Picture from when I was building the truck. I don’t have a picture of the double mount but just imagine another two mounts further back.
IMG_1191.jpeg
 
I was looking into those, Giiro or the metal cloak that clip into a uniball type housing. Unfortunately the assemblies get to $80-100 real quick. With 4 needed to mount the motor and trans I was looking for an option closer to poly price.

I did find a Rav4 lower arm bushing that has a 9/16 ID and looks like it would press into a standard size DOM tube. Didn't know if there was a better option.

Amazon.com

www.amazon.com
 
The idea with the 3 point style is to allow chassis twist not to be translated into the drivetrain.

Most people think whatever pos they have doesn't twist, but everything twists, it's just a matter of how much.

Seems like some get away with 4 point mounts and some don't, where just about everyone seems to have good luck with the 3 point method. Edit: at least trail rigs, can't speak for racing.
 
3 point V or 4 point Y
Engine holds torque rotation
Tail holds trans and case with no torque
Leaf spring bushings have good rotation around bolt but not much axial. Leaf bushings can be used at engine only and a more flexible joint at the trans and case. The GM polyurethane trans mount is a good one it has a lot of flex in all directions. The rubber OEM link bushings also flex in all directions.
A polyurethane raced rod end could also work.
 
Motiracer38 said:
I was looking into those, Giiro or the metal cloak that clip into a uniball type housing. Unfortunately the assemblies get to $80-100 real quick. With 4 needed to mount the motor and trans I was looking for an option closer to poly price.

I did find a Rav4 lower arm bushing that has a 9/16 ID and looks like it would press into a standard size DOM tube. Didn't know if there was a better option.

Amazon.com

www.amazon.com
Click to expand...
XJ lower control arm bushings

or Leaf Spring Bushings - Stengel Bros Inc.
 
Thanks benw the stengel link had an RB309 which is the front leaf spring bushing for an 08-19 F250. 5/8 ID, 3.5in long and looks to press into 2x.120 wall DOM. MOOG K202024 alternative is $13ea on Amazon.
 
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