Currently weighing my options for new transmission mounts and engine mounts. My project is a 1991 RS with a stock 305. The motor is being swapped out for the 350 L98. A lot of the stock rubber is shot due to the car sitting for the last 10 years. I am wondering what the viable options are for poly mounts for both, seeing as how most things are no longer on sale. I am also wondering what torque arms are good options today. Any help would be appreciated

 

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If it's a stock L98 you can get by with stock replacement parts. The stock trans xmember is just a simple stamping but a poly torque arm bushing would be a simple replacement. The torque arm itself is also just a simple stamping so no other "rubber" there. Stock replacement motor mounts are also just fine to use. The rest of the suspension should be gone over and anything worn or busted replaced.

TLDR:

Replace motor mount bushings and torque arm bushing. Everything else is not related to the swap, but should be gone over for repairs.

 

Any aftermarket torque arm would be an improvement over stock. Founders has a really good unit for the cost. If you plan on future mods and or lowering the car, look at an adjustable units.

UMI, BMR, Spohn, Founders, all make solid torque arms.

 

The L98 is stock but I plan to do a rebuild. I was planning to do a ZZ4 cam and do a full tear down just to inspect everything. Would upgrading to poly bushings for the motor and trans mounts be worth it at that point or do you think that the stock replacement mounts will hold up?

 

Go with what is cheaper. Poly mounts for stationary parts don't make your car faster. Suspension is different. There is something to be said for a poly torque arm bushing, but not if you're using the stock arm. Stock replacement motor mounts will be more than fine.

 

Suspension wise I was looking into the Eibach Pro-Kit springs as well as Koni Yellows for shocks. The car was my father’s car so I want to take my time and build it up right. I definitely plan on using an aftermarket torque arm I was just debating on several different brands. I was leaning towards the UMI one but also saw the Spohn one and several others and didn’t know if it really made much of a difference between brands.

 

Your plan is solid and since you are doing basic bolt-ons, any of those brands will be more than adequate. I personally have used something from all of those brands and never had an issue when using a stock style replacement. One thing to consider are sub frame connectors. I would install those before any other modification. They do vary in complexity but any set is better than none. These cars are very flimsy in between the front and rear sub structures and it only gets worse when you improve the suspension before addressing this weakness.

 

Yeah that’s already on my bucket list of items. I also picked out a panhard bar and rear control arms. The original motor is already out so I plan to attack the front end while the motor and trans are out of the way, then work my way to the rear end. I’ve noticed a lot of people have made comments about the rear end being weak. Is that going to be much of a concern down the line with the 350 pushing a little bit more power? I know my father swapped 3.73 gears and an LSD into it but I’m not sure much else was done there.

 

A stock 28 spline rear end will be fine with your build. They are a lot stronger then people give them credit for. And yes they are weak.....compared to a 12 bolt.

 

Sounds good. Thank you very much for the info!