Butler Performance Billet Polyurethane Engine Mounts

[NCBadBird1979]

Needing to replace my engine mounts on my 1979 Trans Am that's got a Pontiac 400. I've never seen these before. Anybody running these? I know I've seen guys on here modifying the Chevy polyurethane mounts and inserting them into the clamshell, but these seem to be an upgrade.

https://butlerperformance.com/c-1393551-engine-mounts-plates-cradles-motor-mounts-75-81-f-body-firebird-ta.html

[djustice]

I do not run poly mounts, but i seem to recall having read a post about also changing the transmission mount to poly at the same time. Something about different firmness in in trans and engine mounts could cause craking in transmission bellhousing og the engine block.

[chief poncho]

The issue regarding the transmission mount is when you use a poly transmission mount with rubber engine mounts.  The engine will flex but the transmission won't, thus possibly cracking the case.  You can run a rubber transmission mount with poly engine mounts though, just not the other way around.

[NCBadBird1979]

I went ahead and purchased a pair of the mounts from Butler and installed them over the weekend. Very nice heavy duty mounts.

I had polyurethane ones that you insert into the clamshell on the car previously and was also running a poly transmission mount as well. The only reason why ended up needing to buy new engine mounts is because I just happened to be working on the car and noticed that the driver's side of the engine was sitting a little lower than the passenger side. Upon removal and inspection I noticed that the poly mount in the clamshell had split completely across the bottom from end to end. Not sure when, how, or why that happened. Found that to be weird. Those poly mounts had been on the car maybe 3 or 4 years.

[5th T/A]

NCBadBird,

Thanks for the feedback on these new mounts, they look like high quality replacements. Any feedback on how you like them after driving would be appreciated.

After I did my engine upgrade and drove some miles, I had a problem with my engine sitting slightly higher on the driver's side, maybe 7/16". I ended up just installing new OEM mounts, the engine is sitting level now. I just hope they hold up. It was kind of a pain installing new mounts with the motor in the car and Ram Air exhaust manifolds.

[NCBadBird1979]

NCBadBird,

Thanks for the feedback on these new mounts, they look like high quality replacements. Any feedback on how you like them after driving would be appreciated.

After I did my engine upgrade and drove some miles, I had a problem with my engine sitting slightly higher on the driver's side, maybe 7/16". I ended up just installing new OEM mounts, the engine is sitting level now. I just hope they hold up. It was kind of a pain installing new mounts with the motor in the car and Ram Air exhaust manifolds.

I took the car out and drove it for about 50miles both highway and city a couple of weeks ago. No issues. My only fyi is for those that like to see the shaker scoop shake is that you won't see too much due to the stiffer material and design of these. I had more shaker scoop movement with the clamshell style.

[olds403]

I think you really only need one.  The other side can be stock.  There are not some butler secret.  They are prothane clam shell inserts for like 60 bucks on Amazon.   Not a huge fan of super stiff motor mounts on the street as you will break something else like your transmission case.  Go look at uni-bells as those SFI rated cases or JW.  Seen my far share of cracked cases especially if the trans mount is poly too…

https://www.amazon.com/gp/product/B000NSN3QM/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1