40" Tires - Coilover Kit and 64" Rear Leafs?

[jgolden]

I'm putting together parts for my build and I have a few questions about your "long travel" suspension setup for the front and rear.

Vehicle: 1984 3/4 ton Suburban with 1 ton axles

I would like to run your Coilover conversion in the front with a bypass shock and a bump shock with about 4" lift and 64" rear leafs with big shocks through the bed and 40" Goodyear MTR's. The goal is a low stance, maximum suspension travel and full articulation with a large tire. - I know the fenders need to be trimmed front and back, I'll probably run fiberglass in the front. The rear will be heavily trimmed and I'll Tub the wheel wells if necessary. The vehicle will be used as a Family Expo Rig around Southern California and some Prerunning / Exploring down in Baja, Mx.

Here's my question: What other modifications do I need to address to obtain my setup. Will the 40" tire hit the Air Conditioner, Batteries or anything else in the engine bay at full up travel or full articulation? I would like to get 14" or more of front and rear travel. I'll be running a Dana 60 up front and 14 Bolt rear - Is 4.5" backspacing the correct setup for wheels?

Thanks in advance for your help.
I'm looking forward to starting the project

James

 

[miniwally]

I'm putting together parts for my build and I have a few questions about your "long travel" suspension setup for the front and rear.

Vehicle: 1984 3/4 ton Suburban with 1 ton axles

I would like to run your Coilover conversion in the front with a bypass shock and a bump shock with about 4" lift and 64" rear leafs with big shocks through the bed and 40" Goodyear MTR's. The goal is a low stance, maximum suspension travel and full articulation with a large tire. - I know the fenders need to be trimmed front and back, I'll probably run fiberglass in the front. The rear will be heavily trimmed and I'll Tub the wheel wells if necessary. The vehicle will be used as a Family Expo Rig around Southern California and some Prerunning / Exploring down in Baja, Mx.

Here's my question: What other modifications do I need to address to obtain my setup. Will the 40" tire hit the Air Conditioner, Batteries or anything else in the engine bay at full up travel or full articulation? I would like to get 14" or more of front and rear travel. I'll be running a Dana 60 up front and 14 Bolt rear - Is 4.5" backspacing the correct setup for wheels?

Thanks in advance for your help.
I'm looking forward to starting the project

James

Stephen and Chris can answer better but the really short answer is

It depends. Over all I'm envious of your plan and think your going to like the outcome. I would question why 40" tires, I think that a nice practical tire point is a 37" to 38" tire. 40's just get a bit funky sometimes to work with.

If you get the ride height correct and the front axle pushed forward a little you can probably get by with the AC stuff staying.

I would spend some time with Stephen and Chris on the phone to get things figured out for sure.

Good luck

 

[jgolden]

Yes, I agree that a 37" tire would be an easier option but since the vehicle is so long, I'm looking for Maximum all around ground clearance (It'll be used in the desert and mountain trails, pretty much any trails that she can fit on.
Plus the 40" tires add an extra cool factor and Roll over the big holes so much better!!!

 

[jgolden]

Blazer on 39" Projects

Here's a Blazer on 39" tires with minimal lift. Stock Fenders with Trimming on all the corners. this is an old military rig so it didn't have A/C. this has a similar stance and look that I'm looking for but my Rig is a Suburban.

 

[Stephen]

I don't see any problems with what you're working out, the AC clearance is the only thing that could be an issue and I don't think it'll be a big deal if it is a problem. I do know we fought our shock hoops a little working around the AC in my '88 burb but it wasn't a real problem.

14" of total travel up front is standard with our kit and it's possible to push it to 16 but I can tell you making the extra travel work is definitely more work, especially trying to keep a low ride height. The rear is pretty easy to work with but I would bet that around 16" would be a good practical limit while keeping a spring rate that's usable for a load that can vary a few hundred pounds. I think a way to vary rate and load carrying capacity would make it easier to lighten up the rear springs and allow more travel.

Which brings up another point, by the time you run a good spring, a traction bar system and a good shock you're not far from links and coilovers in the rear. I've had an idea for using a coilover airshock for a truck like yours so that the ride height and spring rates can be adjusted without changing coils and with a bypass shock to do the damping I think it's work considering.

My '88 ended up a good way toward your end goal, our 4 link and a single 2.5 c/o up front and 64's in the rear with a single 2.25" shock under the floor with D60/14ff. We got a full 7 inches of up travel in the front (14" total) at around a 4" lift height and with some custom crossmember work there was room to lower it or get more bump room. We used our production x-member. The rear was TCI 3" springs and a flip so it wasn't really optimized at all and still ran around 14" of vertical. Tires were 35's the whole time and overall it rode and drove great. With a stronger engine and trans I wouldn't have any trouble using it the way you want to use yours.

I'm in the same boat on the tires, 37's are entirely practical (odd how we've come to a point that sentence makes sense) but 40s are awesome.

We can work out ideas on shock sizes and tube layouts and stuff easily enough but something to budget for is working with a shock tuner directly when the truck is done to dial it all in. You'll have enough time and money in the shock package that it'll be worth it to get some good help making it all work just right.

Backspacing really depends on the whole package but 4.5" is in the ballpark. We run the TrailReady HD17s with 3.5" backspace on just about everything. Somewhere between 3.5 and 4.5 is fine. For your use I think I'd keep it a little wider.