Uberlast

Need some guidance on this, I have a 1971 911T that currently has a Chevy V8 in it (the way I bought it) I picked up a wrecked 85 Targa to use as a drivetrain donor and wondering if it makes sense to swap in the trailing arms and rear suspension too. My goal for this car is build it into a 1973 RSR hotrod / tribute / outlaw , I won't be using the torsion bar setup as I'm going full coilovers front and rear. I have to start stripping the 71 and the 85 and start selling off parts to fund the rest of the build....

myflat6

good thing is that the rear trailing arms are aluminum vs. the earlier steel versions. keep in mind that you will need to beef up the cross member to handle the force from the coilovers. my buddy tperazzo is doing a similar build with his '74. you may want to check out his Youtube channel as he has done a bunch of work to prepare his car for coilovers. https://www.youtube.com/user/tperazzo/videos

r911

I'd lose the coilovers unless it is going to be a racer - and even that depends on the class.

I have Al R. bananas on my '73 (they are form a '77 IIRC) - it is not hard to do.

I also have a 3.2L in mine - with PMO carbs. Also not hard - will you keep the EFI?

Uberlast

Thanks for that input, any specific mods that were required ?.
During my research, it seems like the later rear arms may widen the track, I'm not sure if there is any other geometry difference that suits modern tires better, I'm hoping there is. I don't plan on tracking the car, but again, from what I have read, coil-overs are supposed to be superior even on the street. I know chassis reinforcements are required and I will weld those in.
I'm going to sell off the factory EFI and going with ITB's and modern EFI, for that I'm going to use a SpeeDuino, might be the first one with such a setup.

r911

coil springs allow the manf. to put a taper into the spring or the winding to alter the spring rate at extreme travel - otherwise, I dunno why they would be superior

coil-overs were used by Norbert Singer to 'cheat' the rules for stiffness w/o actually going outside the rules

If someone says they are superior for street use, I'd ask why

Dave Inc.

For a street car you can go to a progressive rate spring which will be more supple during normal driving to help soak up little bumps in the road, but still deal with larger bumps with more suspension travel. It also makes it a heck of a lot easier to adjust ride height.

Progressive rates are really the only benefit for a dedicated street car though.

Uberlast

Yes, this will pretty much be a street car and I did find mention of the ride quality improvements in various coil-over suspension "debates". The easier ride height adjustment is one of the more important factors as I also really like the look of a lowered car. I'm almost finished my garage rebuild and can't wait to get started on the car. It's been sitting for almost 2 years while waiting for me to get my work area's cleaned out, rebuilt and outfitted to start the project.

r911

is it a bare tub or will it be?

one of my regrets is not stitch welding my car for stiffness

you can also call up Dave B. (TRE) and ask about some add on pieces to stiffen it - I hear they worked wonders with the "raspberry car" ...