'73 Trans Am LS3 Swap - advice on new front subframes

[v8 stingray]

After having my project '73 Trans Am 455 sitting in in the garage for the last 12 years I'm finally getting to build the project this year and I've just purchased a crate LS3 and 5spd Tremec. Unfortunately thought I've lost my garage due to divorce, so I'm getting a local shop to do the build. I'll be getting a full rebuild and I'm looking to modernize the handling (and reduce the build effort!) so I'm thinking of buying a new front subframe. Any advice on whats out there in terms of after-market ones? Im aware of the DSE one etc.

It wont be track use, but it will be a pro-touring style with a full rebuild. Any advice on whats out there, and if anyone has used them on a 2nd gen f-body would be great!

159945
thanks!
Rowan.

[BMR Sales]

if you are not Tracking it, just doing a Pro-Touring Build, you could redo the Suspension, & Seam Weld the existing subframe. The aftermarket SF's are nice but in addition to the Cost, I think shipping to you would be very pricey!

[c4racer2]

The factory subframe is pretty good on a second gen. There are some things you can do to make it stiffer - add subframe connectors, solid body mounts, and the G-braces from PTFB. The main advantages of the full subframes are rack and pinion steering and clearance for really large front tires like 315's. If you are going to run a more modest tire set-up like 245/275 or even 275's all around on 18x10" wheels - the factory frame and complete re-do of the suspension works perfectly well. And R&P is nice - no doubt, but the latest 12.7:1 boxes 700 or 600 series provide very nice feel and feedback, I think that's a very good way to go - I have a PSC Pro-Touring unit on mine with a KRC race pump. If you want a complete solution from one vendor look at Turn1.

I am currently looking at both SpeedTech and RideTech for front suspension - either way using the RT coil-overs. I think both are well designed and would give you a similar result. Both also have a nice matching full rear suspension to go along with them. I think these two companies offer the best comprehensive complete suspension design to bring the car up to modern handling standards. But Detroit Speed also has a nice bolt on suspension for these cars - at least on the front. The rear is a lot more fab intensive - not so bolt on, but then again none of the rear full redesigns are all that bolt on.

Also depends a bit on your budget - are you allocating $10K+ for the suspension and chassis? Then any of those 3 vendors would be a good choice.

Or do you want to get a nice set-up for 1/2 or 1/3 of that cost? That opens up the choices a bit more - BMR and UMI have some nice packages using traditional leaf springs.
You could even just go with the Hotchkis TVS set-up for the second gen and be pretty happy - that's what I have on my car now.

I think define your budget and desired tire sizes too. If you want a 315/335 combo then you need a 4-link or Torque-Arm rear suspension with mini-tubs, plenty of fab work and the big 3 vendors will give you the most ready to go solutions.

[TBART70]

I have the Speed Tech set up on my 70 Camaro stock frame , nice kit full Ride Tech coilovers . Drives great.

Ride Tech also has a front kit with Speed Tech spindles.

[c4racer2]

Ride Tech also has a front kit with Speed Tech spindles.

they do?? Nothing on their website about that.

[TBART70]

https://www.ridetech.com/products/track-1/

[c4racer2]

That doesn’t show up when I search under 70+ f-body. Only the max spindle upgrade to the true-Turn suspension and rear ends show up under track 1 for second gen.
Would be good to know more about what else they do offer for our cars under track 1 program.

[v8 stingray]

Guys,

many thanks for the replies - some great food for thought there. i've been thinking about this a lot and have decided to go for the full DSE front subframe and rear hydralink suspension with the adjustable coilovers.

Quick question - do you know what width wheel up front and in the rear without mini-tubbing? Am I right in thinking I can go a 18x10" up front and a 19x12 in the rear?

[c4racer2]

Seems to me you can run a 315 tire in the back without the leafs in the way even without tubs. I have a 295-45-17 on a 9.5” wheel with 5.5” bs and it clears the fenders fine. You could probably go up to a 6” bs and a 11” wheel and 315 tire within the stock wheel wells without the leaf springs in the way.

[v8 stingray]

Seems to me you can run a 315 tire in the back without the leafs in the way even without tubs. I have a 295-45-17 on a 9.5” wheel with 5.5” bs and it clears the fenders fine. You could probably go up to a 6” bs and a 11” wheel and 315 tire within the stock wheel wells without the leaf springs in the way.

Perfect, a 315 and 11" wheel would be ideal as I want to have a health deep dish on display at the rear. Whats the best way to measure this to be 100% when we have the DSE kit installed?

[v8 stingray]

Ok, so ran into another slight problem today. Was advised that the LS Swap kit I was going to buy wont work with the full DSE setup. This is the kit I was going to buy http://www.brphotrods.com/mm5/merchant.mvc?Screen=PROD&Store_Code=BRP&Product_Code=CPS206&Category_Code=CPLS - does anyone know of another LS swap kit that will work with the DSE front subframe and rear Hydralink setup?

[patriot68]

DSE has everything you need

[c4racer2]

Perfect, a 315 and 11" wheel would be ideal as I want to have a health deep dish on display at the rear. Whats the best way to measure this to be 100% when we have the DSE kit installed?

I would get the rear suspension installed and then measure for wheels. Front is easier - pretty much a 5.75-6" bs will work to run 275's and if you go smaller tire it's less critical to use that much bs

[F-Body International]

Seems to me you can run a 315 tire in the back without the leafs in the way even without tubs. I have a 295-45-17 on a 9.5” wheel with 5.5” bs and it clears the fenders fine. You could probably go up to a 6” bs and a 11” wheel and 315 tire within the stock wheel wells without the leaf springs in the way.

Who makes 295-45-17?

[v8 stingray]

DSE has everything you need

OK, reached out to DSE to see if they have a kit that works with the TR6060.... from what people are telling me they have a crossmember designed for the kit but only for the T56 Magnum.I know these are very similiar, but I've been told we will need to modify that to fit.... ideally, just want to get one that was designed for the TR6060.

[dhutton]

Ok, so ran into another slight problem today. Was advised that the LS Swap kit I was going to buy wont work with the full DSE setup. This is the kit I was going to buy http://www.brphotrods.com/mm5/merchant.mvc?Screen=PROD&Store_Code=BRP&Product_Code=CPS206&Category_Code=CPLS - does anyone know of another LS swap kit that will work with the DSE front subframe and rear Hydralink setup?

You dodged a bullet there....

Don

- - - Updated - - -


OK, reached out to DSE to see if they have a kit that works with the TR6060.... from what people are telling me they have a crossmember designed for the kit but only for the T56 Magnum.I know these are very similiar, but I've been told we will need to modify that to fit.... ideally, just want to get one that was designed for the TR6060.


Making a suspension choice based on a trans crossmember doesn’t make a whole lot of sense imho. Mods are likely minor...

Don

[c4racer2]

oh those are MT Drag radials. Nobody makes a 295 in 17" that I can find any longer. I am moving to 18's.

[patriot68]

If your having a shop doing the work they should be able to fab a crossmember

[c4racer2]

You dodged a bullet there....

Don

- - - Updated - - -




Making a suspension choice based on a trans crossmember doesn’t make a whole lot of sense imho. Mods are likely minor...

Don

Agree - in that case just make your own crossmember - or have the shop installing the suspension make one. That will be a couple hours labor. No big deal.