Unchewable, the D170

[kingcrunch]

Hi.

Ok, i have been thinking for a while about how to start this build thread, how to start this project.
A while ago i saw Freiburgers Chevy C10 in the "muscle truck" installment of his and Finnegans show "Roadkill".

A fast, low mid 80s truck. That kind of rang a bell. A little later after that i stumbled across Rob Philips red C10. Call me hooked.
A few weeks ago - while knee deep in my other project vehicle (a '85 Dodge W250, stock restoration) - i decided i want to dig deeper into that fast truck topic that would not let me sleep.

Stumbling across Mark Boveys Targa Truck was inevitable and pushed me into the right direction: stock frame with cage and cross bracing, mostly stock suspension with tweaks, really good brakes, healthy engine, wide tires.

And i want the damn thing to run 170. Even a slighty hotter diesel euro-station-wagon runs like 150mph these days and i want to distinguish my build from that
I am actually sane and have a valid driving license for quite a while now, in case you wonder. It's a long term goal.


This project will have to take some large hurdles. Some of them are so problematic that i don't know whether the project can be completed. The largest part of that is the legislative over here.
We have a very well sanctioned type of race going on here every day called "dailly traffic". It does not command to have a cage but that's about it. I will have to adhere to the rules, maybe with a little bending but if i break them, it's not gonna work.


So bear with me when i say "no - can't do that" to a lot of things.

Alex

[kingcrunch]

After the initiation, i would like to give you a short rundown of the kind of hardware i want to work with.

the vehicle
I dig the 81-89 body style of Dodge pickup trucks. I own a '85 already and i want something a little younger.
Mainly because from '86 on they came with fuel injection. This will play a role in registration lateron.

The sheet metal is all the same from 81-89, the grilles vary. Typical engineering of that time...

So i want to use a '88 D150 shortbed, regular cab, rear wheel drive. Ladder frame, strut rod and a-arm front suspension, half elliptic leaf spring in the rear.
I plan to reinforce the frame by building and adding a crossbrace and running the cab cage down to the frame.

drivetrain
I want fuel injection, catalytic converters, instant engine starts in every weather, read: a modern mill.
I also want lots of power and reliability, because i want to be able to drive this whenever i want, whereever i want.
Since i drive a lot on our local highways (the autobahn), one or two overdrive speeds would be very nice - notice i also like fuel economy.

I think a modern 6.1 or 6.4 Dodge Hemi engine with a 545RFE transmission should do the trick. For "phase 1".

front suspension
New bushings - maybe aluminum and delrin (will have to be fabbed) all around.
6° or more caster, depends on what i can do. Spherical bearings instead of rubber bushings on the strut rods.
QA1 shocks.


front brakes
Uh, the great unkown.
Nobody makes stuff for Dodge trucks. Shame on you aftermarket guys. Just kidding. No demand, no market, right?
For beginners i will start with a 11.75" x 1.25" rotor and the stock caliper and do something for brake pressure.
I could either work with a hydroboost system or change the pedal ratio in combination with a smaller diameter master cylinder.
The tires will have a smaller diameter than stock, this will also help.

Add some cooling ducts to the fronts and go for it. In the back - depending of the rear axle to be used - i want to go for discs instead of drums.
Totally unknown for now, because the rear axle is undetermined.


tires and wheels
10x18 with 285/35 R18 front and rear
I am not a 100% decided on the design i want but the OZ Crono wheel comes close.

[kingcrunch]

Quick explanation for the thread title "Unchewable, the D170"

"Unchewable" because i like to bite off pieces too big to chew.
"D170" because it's a D150 that shall run 170.

[kingcrunch]

safety
One big concern with this project is safety.
Safety for the driver and passenger mainly.
The base vehicle would probably fold up like a can when it hits something at any triple digit speed.

A cage will be installed to keep the cab intact in case of a roll over or t-bone accident. The rear bars shall go down to the rear of the frame.
I have no idea on how to tie the cages feet into the frame structure yet. Construction and building of the cage is a task that will be outsourced to a company that builds safety equipment.


While i adore bench seats, they are a chore in every curve you take.
I am undecided on whether i want a nice good adjustable long-distance leather seat (from a modern Mercedes for example, i like the amg seats in my W204) or something all-out-racing.
Most likely the first or similar...

aerodynamics


For the problem of aerodynamics i have a few ideas but these will need to be put to the test when it's running and ready for testing:

- Air dam on the front (like a 90s Chevy C1500). It will include two funnels and ducts for front brake cooling, because race truck 8)

- lexan headlight covers

- To bleed air pressure from inside the engine compartment and to get rid of the immense heat a turbocharged engine (hint for drivetrain phase II) will produce,
i am thinking about creating two large cutouts into the hood and add a small lip on the front of each cutout. Yes, this is so stolen from Marks targe truck.

- Air guides on the roof which double act as a mount for a small wing on the rear egde of the roof to act like a kammback and direct the air stream to the end of the bed
This depends on where the air flow actually comes down below the silhouette of the bed. Shortbeds have less of that barrel-roll-vortex behind the cab... maybe it's not needed.

- at the end of the bed there will be another wing attached to the tailgate for some downforce on the rear end.

I am not sure whether i want a half or full tonneau cover or any cover at all...
Not sure what to do about the wipers too. They might need a cross-pin through the arm and shaft so they don't fly away at speed ;D

I am looking into the stuff ecomodders do for more mileage at the same speed. I can replicate that for more speed with the same bad mileage 8)

http://tylerlinner1.kinja.com/a-prac...ods-1718476233

[kingcrunch]

addition to aerodynamics
A D150 of the era that i like has about 29 sq ft of frontal area, which is 6 less than a Ram SRT-10, yay!

[kingcrunch]

body
Old-school rallye car stuff will be done here:
- stitch welding of all body seams
- doubleing the number of overlap spot welds using a professional spot welding machine
- simple reinforcement panels in areas where the is no boxed structure, like the lower b-pillar, lower a-pillar, etc.
- as mentioned in "safety": a cage


frame
I want some kind of reinforcement, but welding on the frame is illegal for safety reasons. I can not drill and mount anything on the flange, because that is where the strength comes from.
Also the manufacturer disadvises to do that.
So the plan is to build a - as rigid as possible - cross-bracing structure, that bolts in.
I will be using material that has about the same tensile strength as the frame material, called S355, which is a low carbon structural steel. It's relatively cheap and easy to aquire.
Boxing the frame rails is an absolute no-go in my area.

[Motorcitydak]

Really looking forward to seeing this come to reality!

[Yukon Cornelius]

Frohes neues Jahr!

[kingcrunch]

Thank you! Had a great transition, cooking with friends, glass of wine, all good.

I too can not wait to see this happen. I have so many ideas i want to try and build...
But right now all this is about is contemplating and thinking up a proper concept before building.

[bovey]

As a GM truck owner I love seeing different brands and off years being built, I was looking at this era of Dodge truck this summer, a red short box, thinking that is would make a killer build. Then here you are actually getting ready to do it, awesome.

Then to start reading your thread and find out myself and the Targa Truck were inspiration; well, that is very flattering. Thank you.

Building a truck is an interesting experience you will meet a lot of people that say it can be done, but I assure you it can be. Besides there have been plenty before us attack to build them without issue.

I've read your plans a couple of times and have a few comments. My truck worked, but depending on how serious you want to get later on, you might be wise to set-up your game earlier on.

1) Front suspension.
I took a peek at some photos of the strut arm suspension. I'd do some homework and make sure you can meet your performance expectations with that set-up. You might be further ahead to get an IFS to save time and money over the long run. I'd be pulling the springs and dropping to your desired ride height and then putting the suspension through the range of travel, WITH the steering in different positions to see what the geometry in doing. Even better drag it to a motorsports alignment shop and have them measure it.

2) Suspension components. There is not a day I don't regret going to a 9" floater sooner than I did. Actually, I am just about to do this. Why? Safety, strength, and it really opens up your brake options.
On a truck, I'd also look into going with a stock car style spindle, Coleman for example. Personally, I've been dealing with Ron Sutton and I'm going to get a set of his design, which are manufactured by Coleman, if I recall.

Stock Car Spindles? 9" Floater? Why?

3) Brakes.
If you upgrade to the heavy duty spindles now and the 9" now, you get the best selection of brakes. Period.
Everyone makes tough-ass brakes for these parts with loads of options. I'm looking at Wilwood, Brake Man and Stop Tech. I was at the PRI show this year and was able to look closely at these manufacturers and I was very impressed with the racier stuff vs. the "Pro-touring" versions. For a heavy vehicle you want to be able to deal with heat. My current D52 and Wilwood set-up stop the truck great, they just can't handle the endurance. Venting. Venting. Venting.

On the subject of brakes, take a good hard look at your petal set-up. Trucks are very tricky to heal-toe. My foot is just wide enough to get the loud petal and the clutch, but it's also easy to miss...

4) Roll Cage
If I was doing it again, or from scratch, I would cut the inner body out of the cab and fit the cage and close to the exterior sheet metal as humanly possible and re-fit the inner body again. I'm 6' tall and space is limited. Once you put a proper seat and harness in, there is even less space.

Love the idea of this build. Please post loads of photos.

Have fun.

Give'r.

[kingcrunch]

Hey there!

Concerning the changes in suspension and brakes you suggested i am all for it but there's the guy in the blue work coat with his paperwork that permits the use of flat-out racing only brake components.
I'll be glad when i get allowance for the rear disc setup i want.

I also plan to aquire a suitable piece of software to simulate the stock suspension setup i have and the alterations i want to do.
This way i think it will be easier to evaluate its problems and the changes i find necessary.


rear axle
I have spare Dana 60 full floater housings from my previous 4x4 Dodges.

So my plan is to lop off the axle ends and have Moser D60 housing ends welded on square.
Then have custom 30-spline axle shafts made by Moser (actually not that expensive) and use the Wilwood D154 Rear Parking Brake Kit.
A good working parking brake is absolutely mandated by law in my area.

I am thinking about building a 0.5° toe in into the axle on each side, i have read that more angle will kill bearings and splines.

The diff will be re-geared if necessary.
For starters it will stay the 4.10:1 it is right now. I have a set of 3.55s in my W250 that needs replacing (because of OD transmission swap), so more options here.

The decision was made with the following things in mind:

- more rear end weight (although it's more unsprung mass too)
- availability (i have it)
- overall strength (and much of that)
- no crush sleeves to set pinion depth


rear suspension
The stock suspension on a Dodge truck is a setup consisting of two 2 1/2" wide, 5-leaf, 1650lbs spring packs, with a shackle pointing upward on the rear ends.
The axle is bolted underneath that spring pack. The stock bushings are a steel and rubber design, with an outer and inner steel shell.
The shocks mount to the u-bolt plate, Chrysler did not use a staggered shock design. They tilt inward and a little to the rear but that is it.

To reach target ride height the axle will be relocated above the spring packs, which means removal and re-attachment of the spring pads, custom u-bolt plates and shock mounts.
The springs will be disassembled, checked and fitted with nylon pads on the ends for less friction.

I am thinking about Caltracks as a traction aid and maybe a panhard bar, but i doubt i will have a lot of side to side deflection. I will have to learn more about roll centers and how the panhard bar affects it.
I will add welded (psssht! Don't tell anybody i welded on the frame parts) reinforcements to selected areas, such as the shackle and the front and rear spring mount.

Should i limit downtravel with straps, so it does not damage the shocks? I don't know how QA1s handle the weight of a D60...


I will have to make that setup handle the best i can. I would have a hard time to get a linked rear through legally.

[bovey]

Ah, you have very similar laws to us here in Canada. Some provinces have the no weld rule. In Ontario we still can weld, for now.

We have the parking brake rule here too. I wanted to use the D154 rear set-up on my 12 bolt, but those callipers do not come big enough to match my stock fronts. I suspect you might run into the same issue. Have someone run the braking force numbers before purchasing. The brake man offers a good option for the rear and has mechanical parking brake options as well. Otherwise brakes get pricey fast. I don't know much about Dana60s, but make sure yours can handle lateral loads okay. My 12 bolt GM was a disaster.

You will not need to add weight to the rear, trucks are not as out of balance as everyone thinks. The "light rear-end" is really a symptom of the trucks being set-up to carry loads, not the front rear weight bias. Also, in my time doing this I've had many people smarter than me tell me a balanced vehicle is more important that 50/50. Not that 50/50 is not desirable. Having a balanced set-up keeps the vehicle predicable. This turned out to be the secret of why the Targa Truck handled the way it does. It was only out 20 lbs. corner to corner when I finally got around to weighting get truck. It's 59% front 41% rear. Total weight 4386 lbs fully rally loaded with jacks, tools, spare tire, etc.

I have a guy I race with that runs a Impala SS and he limits the suspension with chains with great success. In some cases he actually ties the car down for greater spring rates. This in not my area of expertise. Too be fair, none of the this is.

Again, good luck. Looking forward to seeing your progress.

[kingcrunch]

brake math

It took me quite a while to figure stuff out but it turns out that this tech is not too complicated. But please correct me if i am wrong.
Some of the values seem a bit high to me.

I need to write down a few given (right now, may be altered if needed) parameters of the preliminary setup:


- front caliper piston diameter: 3.09 inch
- front caliper piston area: 7.5172 sq inch
- front pad surface area (outer/inner): 10.12 / 9.43
- front rotor diameter: 11.75 inch
- front mean rotor radius: 5.08 inch
(assumed/calculated: rotor radius - (pad friction surface height / 2)
- brake pedal ratio: 3.85:1
- dual diaphragm 8" brake booster gain @ -8psi vacuum: 499lbs
- tire radius: 14 inch
- master cylinder bore diameter (no step bore): 1.125 inch
- master cylinder bore surface area: 0.994 sq inch
- coefficient of friction: 0.35 (assumed for stock pads)
- tire: 285/40 R19
- tire diameter: 27.98 inch
- driver braking pressure: 100 lbs


Ok, i did it all again because i had forgotten (how did that slip by?) that this truck can be had with a 8" dual diaphragm brake booster.

Here are the calculations for the front axle with 1/2t parts. The rotor comes from a fullsize passenger car for the 5x4.5 bolt circle.

front 1/2t
878,4 lbs/sq in * 7.5172 sq in = 6605 lbs = clamping force
(6605 lbs * 0,35 * 5,08 * 2)= 23488 = brake torque lbs in
23488 / 14 = 1677 = wheel brake torque
1677 * 2 = 3355 = per axle brake torque
stock hardware

I listed a few options for rear brakes i have gone through without finding suitable stuff:


wilwood d154
878,4 lbs/sq in * 1.98 sq in = 1739 lbs = clamping force
(1739 lbs * 0,35 * 5,25 * 2)= 6391 = brake torque lbs in
6391 / 14 = 456 = wheel brake torque
456 * 2 = 913 = per axle brake torque
brake bias fr/rr in %: 86:14
by far not enough

rear eldorado caliper (small gm with pbrake)
878,4 lbs/sq in * 3,24 sq in = 2846 lbs = clamping force
(2846 lbs * 0,35 * 4,8 * 2) = 9562 = brake torque lbs in
9562 / 14 = 683 lbs = wheel brake torque
683 * 2 = 1366 = per axle brake torque
brake bias fr/rr in %: 68:32
close but not enough

rear large gm (with pbrake)
878,4 lbs/sq in * 4,55 sq in = 3996 lbs = clamping force
(3966 lbs * 0,35 * 5,08 * 2) = 14212 = brake torque lbs in
14212 / 14 = 1015 = wheel brake torque
1015 * 2 = 2030 = per axle brake torque
brake bias fr/rr in %: 63:37
too much, can be adjusted with a prop valve
This last option needs a 1.24" wide rotor and makes it harder to find a suitable one and also i will have to make custom adapters, which is not a good thing to boot.


I am asking the Wilwood company if they could piece something together for me that i think might work. Still most Wilwood calipers lack proper dust boots but maybe i'll get through with that.

[kingcrunch]

Now with correct numbers... duh.

[kingcrunch]

heureka
I think i found a nice solution for a good rear disc brake setup (although thermal mass could be a little higher on the rotor):

wilwood 120-11482 caliper with dust boots and pbrake kit 140-11395

878,4 lbs/sq in * 4,80 sq in = 4216 lbs = clamping force
(4216 lbs * 0,35 * 4,7 * 2) = 13871 = brake torque lbs in
13871 / 14 = 990 = wheel brake torque
950 * 2 = 1981 = per axle brake torque
brake bias fr/rr in %: 63:37
too much, can be adjusted with a prop valve

[kingcrunch]

heureka
I think i found a nice solution for a good rear disc brake setup (although thermal mass could be a little higher on the rotor):

wilwood 120-11482 caliper with dust boots and pbrake kit 140-11395

878,4 lbs/sq in * 4,80 sq in = 4216 lbs = clamping force
(4216 lbs * 0,35 * 4,7 * 2) = 13871 = brake torque lbs in
13871 / 14 = 990 = wheel brake torque
950 * 2 = 1981 = per axle brake torque
brake bias fr/rr in %: 63:37
too much, can be adjusted with a prop valve

Well heureka - NOT! Unfortunately Wilwood told me that this combination does not work out.
Again i am looking into all kinds of options right now.


@Mark:
Did you know the D154 caliper is available in 4.12 sq in and 4.90 sq in piston surface area?

That would be my bail-out plan...

[bovey]

[QUOTE=kingcrunch; @Mark: Did you know the D154 caliper is available in 4.12 sq in and 4.90 sq in piston surface area? [/QUOTE]

Yeah. Sadly, there are not big enough for my application. Based on the number crunching for my truck, I need around 5.9ish sq/in for the rear calipers.

[kingcrunch]

I have seen the chart Ron made for your truck but that number is both calipers added, while the surface area i quoted is per caliper (times 2 = 8.24 sq in or 9.8 sq in).
Just beeing curious because my truck has even larger stock front calipers (3.1" piston bore, 7.55 sq in per caliper).

I assume it would be better to choose components that match as close as possible, to minimize the amount of hydraulic pressure wasted in the proportioning valve...

[kingcrunch]

The whole Wilwood-thing just took a bad ending when i followed your hint on bearing type and sideloads.
I am thinking about a big bearing Ford 9" with 76-79 Lincoln Continental disc brake setup and shafts and discs drilled for a 5x4.5 bolt pattern.

[bovey]

The whole Wilwood-thing just took a bad ending when i followed your hint on bearing type and sideloads.
I am thinking about a Ford 9" with 76-79 Lincoln Continental calipers and discs drilled for 5x4.5 bolt pattern.

I'm sorry that is the case, but happy you found out before you spent the money. I wish someone would have been more honest with me when I was at that stage. Be very tough on details like this. You can get away with more if you are just doing the Pro-Touring "look", but when you want to be hard on it, let alone take the vehicle into less than safe situations, these things matter.

Also, understand your front spindle bearing loads.