1970 C10 (Suspension/traction questions)

[rjcamel2355]

Hey Folks, been digging through this forum/thread and gathering knowledge for awhile now. I've been through the Suspension 101 thread, and picked up some really good information. Hoping some folks chime in and give me some more tips/ideas below is what I'm working with:

1970 C10 Long Bed
408CI LS engine
E85 (Fuel cell located in toolbox in the bed, -12AN feed line, 10AN return line using a magnafuel 750 fuel pump)
Holley Terminator ECU
6766 billet wheel turbos (.81 AR, going to change the housings to a .96 AR)
TH400 with a billet 1/2 brake, RMVB
Front and rear roll pans, drum brakes in the rear, front disc conversion
325/50/15 MT Drag Radial on a 10" rim
12 bolt with 4.11s and an eaton posi
adjustable panhard bar
Truck has been lowered roughly 5" rear, 3" front
Viking rear coilovers with 350LB springs
90/10 Competition engineer front shocks (with 3" front lowering spring) Shocks have been relocated at the tops.
Trailing arm mounting bracket has been flipped
Engine is set back as far as possible, and as high up as possible without altering the firewall

Attempting to leave on 5PSi, making a total of 18PSI. I have not taken this truck to a drag strip yet, been using a local ghost road, but it is very traction limited even using 2nd gear leave it's spinning for the first 35-40 feet. Over 10mph rolling the truck feels great, seems to bite good and pulls very well. It simply refuses to hook from a dig, from videos it seems the front suspension beings to rise, hits its limit, unloads the rear and goes straight to spin city.

I believe my biggest problem is the lack of front suspension travel, which I plan to address in the next week by putting the truck on some scales and getting some weights. I've also picked up an adjustable trailing arm bracket, currently the factory mounts are flipped.

[rjcamel2355]

Got the truck weighed yesterday evening, was a bit heavier than I expected, but....
2440 on the front
1660 on the rear

That's with 20 gallons of fuel, and my 230lb self sitting in the drivers seat.

[litebulblsc]

Are you trying to get it to hook on the street or on the track?

[rjcamel2355]

Street would be nice, I don't think I would have too much issue on a sticky track, but unfortunately I haven't had the chance to test that theory yet.

[rjcamel2355]

Spoke with the folks over at Landrum springs on Friday, they sold/shipped me a set of 18" long, 5" round, 250LB springs for the front based on my weights.

Removed the stock trailing arm crossmember (Boy those rivets are fun.....) and installed an aftermarket unit with adjustable holes.

Currently trailing arms bolted to the lowest point, coilovers adjusted (Rear fenders sit at 29" from the floor to the lip) and pinion angle is around -1*.

Transmission crossmember will go in today, it's a tubular unit, nothing spectacular with this part.

Driveline is 60" one piece, 4" aluminum, looks like it has a contact ring where it touched the old crossmember, will have it checked, balanced and new u joints installed.

[68racer]

The rear springs are a lot stiffer than mine. I run 180lbs that are mounted just behind the axle on the end of the trailing arms.

[rjcamel2355]

I've reached out to the folks I got the coilovers from, they're supposedly 300lb springs, but I believe they're still too heavy. Mine are mounted in front of the axle at a slight angle, will likely address this when the 9" gets installed.

The 250lb springs from landrum are incorrect the gentleman on I spoke with (one of their dealers) originally quoted me for 250lb springs, but now says I need 225s... however there not returnable, and at $240ish a lick I'd rather not keep trying to get lucky.... also theyre a nightmare to install. I got one side in and it actually raised the front of the truck 3-3.5" (rear sits at 28.5, front sat 29ish, and now the front sits at 32 3/4-33.25)

So chasing my tail a bit still, but making some progress. Replacing the upper and lower control arms with some tubular ones as my current ones are OEM originals.

[68racer]

I got this information from this page, I hope it helps.

[rjcamel2355]

That's for conventional coil springs though I believe? Running a cpp coil over in the rear and a conventional coil style spring in the front.

My biggest issue currently I believe is weigh transfer from the front to the rear. I've read so much about spring rates and lengths my eyes hurt lol

[Swiftshifter68]

Definitely keeping an eye on this thread, as my '67 has a similar turbo'd iron-block LSx combo', albeit with a T56 Magnum and milder 3.42's. I've got a bit more weight behind the axle with my underbed fuel tank, same Viking d/a coilovers with 350lb. springs, with CPP/Speedway 2" drop front coil springs (1,100lb-in) and cheapie GR-2 front shocks on relocators.
Hoping to have this sucker running/driving in the next few months, as the Redwood Rally 2024 is quickly approaching on the horizon! (September 17-21) A Truck Class has been added this year, but I'm stickin'(!) with the 3-Pedal Class!