'72 K5 - Greg's @MightAsWellK5 Build

[ZooMad75]

There is a guy on here with a K5 from busted knuckle. I can't remember his handle at the moment. He has a build thread for a 76/77ish K5 with what's started out as an LS swap but changed to a later LT (di) engine. There a a couple of videos on the busted knuckle YouTube page too.

He might have some insight on it.

 

[ashman]

need to understand the important criteria involved and insure they will be compatible with hydro-assist steering.

Looking at the system, it's just a regular hydroboost with a master/slave attached to the front. I don't see how that would have any effect on hydro steering. In fact they mention on their page that they port the hydroboost system.
"We port the hydroboost units for more flow so the unit is not a restriction to the steering system."
Lots of guys use hydroboost and hydro assist without modifying the hydroboost unit already so I'm sure you're good to go.

 

[JoshHefnerX]

Seems like a solution, but it's more complex, larger and heavier overall.. Do you need to save that space - and do you have to go w/ hydroboost? If you're concerned about vaccum you could mount a remote vacuum pump and just use a vacuum brake booster also...

 

[Truckman4life]

I remember seeing an air over hydraulic conversion they did on that Stacy David show many years ago. Of course it was a medium duty with an air system and hydraulic brakes anyway. This one came up on a quick Google search. https://www.powerbrakeservice.net/aibrsywi1mac.html then you just have an air foot valve on the firewall. But this would add a bunch of stuff and if you don't know air brakes and all that it's a lot to add to a project.

 

[Greg72]

Seems like a solution, but it's more complex, larger and heavier overall.. Do you need to save that space - and do you have to go w/ hydroboost? If you're concerned about vaccum you could mount a remote vacuum pump and just use a vacuum brake booster also...

Yeah, I'm a little tight on space at the firewall so I was really just looking for a good way to relocate the majority of that system. (see photos below)

Also have some serious concerns about being able to "hold back" this truck when it's in compound low-range (~140:1) with probably 500Lb/Ft of engine torque at idle being multiplied through all of that gearing.
Hydroboost is just a proven way to get a LOT of multiplied PSI without a lot of pedal pressure... so it seemed to be a good way to get massive braking power without an overly complex solution.








-G

 

[mrk5]

I've got hydroboost brakes with ram assist; it just takes a little extra effort bleeding the system in my experience.

Also have some serious concerns about being able to "hold back" this truck when it's in compound low-range (~140:1) with probably 500Lb/Ft of engine torque at idle being multiplied through all of that gearing.

-G

Yes, I think that is something worth considering. With the Magnum and NP205 in low, my truck will overdrive the brakes if you're not pushing hard on the pedal or if gravity is working against you. That's with a factory 454. Generally I run in 2nd gear on the trans in full manual and that helps a little. Brakes work awesome otherwise so it's all about the torque and gear reduction.

 

[82355]

With my tired LO5 (350 TBI) and an SM465/NP203/NP205, I can go down a steep incline in Low, Low, Low, and pretty much just stand on the brake pedal. It keeps going. Slowly.

Martin

 

[Greg72]

With my tired LO5 (350 TBI) and an SM465/NP203/NP205, I can go down a steep incline in Low, Low, Low, and pretty much just stand on the brake pedal. It keeps going. Slowly.

Martin

EXACTLY....

According to my maths.... in compound low (5.44:1) there will be close to 32,000Lb/Ft of torque at the wheel that will need to be held back by the braking system.


-G

 

[JoshHefnerX]

I wonder if there's someone at a brake supplier (brembo/ap/wilwood) you could have a powwow with. I'm sure they have the engineering staff that can figure out what would be needed - and if they have suggestions on their products.

Brakes are some place you want it done right - esp if you're concerned.

 

[folkenheath]

With my tired LO5 (350 TBI) and an SM465/NP203/NP205, I can go down a steep incline in Low, Low, Low, and pretty much just stand on the brake pedal. It keeps going. Slowly.

Martin

That's because you are missing your beloved torque converter....

 

[imiceman44]

That's because you are missing your beloved torque converter....

Well he has better

He can press the clutch in.
I had trouble with auto when the idle was high, it kept pushing and overcoming the brakes

 

[Wes Harden]

Larger diameter rotors will solve over powered brakes. Need bigger levers to over come the torque multipliers

 

[folkenheath]

Yes, either one you could take out of gear, but then you lose the engine braking. Although if you are needing to go so slow that you are pushing at idle, taking it out of gear makes total sense.

I like both trans to be honest, I would love a supercharged LS7 with a 6 speed manual in a 65 Chevelle.

I think with the auto it's a balance of finding the right torque converter to give you enough slip not to drive it at idle, but not so much slip that you lose the engine braking if you want it. Of course you also need to match it to the cam/engine/vehicle combo. The issue is, gearing changes the torque converter requirement, so there is no question a lot lower gearing changes the effective stall because the converter has more leverage on the tires.

With the right converter, you won't be applying as much torque at idle. The 4L80E can also lock up on the road so you don't have slip and heat down the highway.

 

[82355]

That's because you are missing your beloved torque converter....

I wouldn't say I'm missing it..........

Was this build always going to be an automatic?

Martin

 

[Greg72]

I wouldn't say I'm missing it..........

Was this build always going to be an automatic?

Martin

Nice....bonus points for obscure "Office Space" reference.


There was a time a LONG time ago, when this build was going to use the stock Unimog404 axles with 7.56:1 gearing... and the plan was to pair it with a T56 6-speed with the .51 overdrive gear to keep it highway friendly.

Once the switch was made to the Mog-9 axles (with ONLY a 5.26:1 axle ratio) a regular 0.75:1 overdrive transmission was all that was necessary, so the T56 was sold off and a 4L80E was swapped in to replace it. I'm not a wildly partisan person when it comes to the manual/automatic transmission debate. In a sportscar, I'd prefer a manual, but for a truck application it's fun to just rest my arm on the door and let the machine do the shifting when needed.

I just downloaded the BillaVista Brake Calculator off the BustedKnuckle website. It says it's for Manual Brakes, but it might still be useful to throw my rotor / caliper specs into it and see just how much braking force I'm going to have available.


-G

 

[imiceman44]

Yes, either one you could take out of gear, but then you lose the engine braking. Although if you are needing to go so slow that you are pushing at idle, taking it out of gear makes total sense.

I like both trans to be honest, I would love a supercharged LS7 with a 6 speed manual in a 65 Chevelle.

I think with the auto it's a balance of finding the right torque converter to give you enough slip not to drive it at idle, but not so much slip that you lose the engine braking if you want it. Of course you also need to match it to the cam/engine/vehicle combo. The issue is, gearing changes the torque converter requirement, so there is no question a lot lower gearing changes the effective stall because the converter has more leverage on the tires.

With the right converter, you won't be applying as much torque at idle. The 4L80E can also lock up on the road so you don't have slip and heat down the highway.

Yeah that needs to be done, how many do that?
I see drag racers do that but no rock crawler I know does

 

[Greg72]

Yeah that needs to be done, how many do that?
I see drag racers do that but no rock crawler I know does

Maybe you know ONE guy.....

- Need to get the engine running with all the new parts (Heath's custom cam grind, Brodix Aluminum heads, EFI, etc) then get it dyno'ed.
- Send those dyno results along with vehicle specs (gearing, weight, tire diameter, etc) to @Greg Ducato here in Texas.
- He will be able to configure a 4L80E / Converter combo that should be perfect... I have no doubt about that.





-G

 

[folkenheath]

Yeah that needs to be done, how many do that?
I see drag racers do that but no rock crawler I know does

I agree, for most it's probably easier to just take it out of gear. Most rock crawlers, except maybe the KOH type, are more worried about how slow they can crawl then their converter stall.

I bet most of the KOH guys have matched converters, as do most of the desert race guys. My trans guy here (Charlie @ ATD) does custom converters for a lot of the desert and short course guys. He was telling me a story of how he got in a crash once in a chase truck and broke his neck and had to get hauled out by helicopter, but they had to wait a long time for the chopper, was not a fun story. Luckily he still has use of all his limbs and brain, I'm sure he's sore on some days though.

I am sure team Greg will get the transmission sorted out!

 

[82355]

Nice....bonus points for obscure "Office Space" reference.


There was a time a LONG time ago, when this build was going to use the stock Unimog404 axles with 7.56:1 gearing... and the plan was to pair it with a T56 6-speed with the .51 overdrive gear to keep it highway friendly.

Yep.

I thought so, but couldn't remember if I was remembering correctly.

Martin

 

[Greg72]

2021.05.17 - UPDATE! WORKING THE I.O.U. LIST....


This build requires me to write a LOT of I.O.U.s to move the overall process forward.

It's not a bad thing, and in many ways it actually makes more sense than fully-rendering every part at 100%.... especially on things like locating suspension links, or rollcage bars. Until you reach the end of that iterative process, there is just no way to know if changes will be required and it's a lot easer to cut out a few small tack welds than a full perimeter weld on a fabricated part. All along the way, I've brought the build to maybe 80-90% completion leaving that final 10% until I was absolutely SURE that no more major changes were coming.

This weekend, it was time to chip away at a few specific areas that have been in the queue for a while dealing with the front suspension. One was frame clearancing and plating for the links, and the other was front driveshaft re-work.


Step 1 was to pull the front wheels off for easier access and hook up the overhead hoist to do some easier cycling of the axle.




Looking across from the driver's side, here's how the day started.







Clearly that is NOT the actual driveshaft angle... it was just lifted off the output yoke to make more room to see and work, but it was still in the way of the frame behind it which needed a complex relief cut....


This is NOT an actual High-Angle Driveline..... this is my 2" PVC prototype with slipjoint. Due to substantially crowded space, it is unlikely that the ACTUAL diameter of the front driveshaft can be any larger than this in real life. More on that later...




With a better view of the frame, the clearancing could begin. The objective was to split a large 3" DOM tube lengthwise and then graft it into the framerails at the spot where the front 2.25" lower links were interfering at full bump. This would create a cool pocket effect and would minimize the amount of material that would need to be removed.

A good shot of that evolving cutout is here:



So obviously, the cuts are making their way into the upper link mount bracket and this will need to be reworked to accommodate. The bracing of the link mount is also too wide and low to allow for the proper cycling of the front PVC driveshaft so that design is being reconsidered as well. (SEE?? A perfect example of a fully-welded part that is now being cut apart out of necessity!!!). This is why so much of the MightAsWellK5 is still just tack-welded together.

At least when this is done on the driver's side there is no upper link mount, so the only real effort will be to cut & plate for link clearance.

At the end of the night there was a cool twilight shot available. It has been raining for most of the day but it stopped just long enough me to capture this..... ( I had a similar photo from my NH garage too and really liked it)







Starting to put some shopping lists together for parts to finish up the axles, brake system, etc. Also bought a couple cans of Steel-It... (one grey, one black) to play around with them and figure out what parts underneath will get each color. It's tempting to bathe everything in black just to make it all disappear, but it might also be fun to let a few details remain in a slightly lighter color so that they can be appreciated.


-G