View Full Version : Sledge Hammer buildup

02-21-2010, 14:20
To bring back some life in this Subforum i thought i'll post my buildup story here. :biggrin:

I wanted a buggy that can withstand my style of driving (i have no fear of the throttle :biggrin: ) and has some serious power. I always wanted a Big Block so i went out looking for some axles.

This is what i found:


Two 2.5 ton Rockwell steering axles in decent shape. That was the moment i knew hat i could use a Chevy Big Block in my new project. :biggrin:

Why these big axles? See the pic below


On the right side a destroyed D60 chromoly axle shaft, on the left the rockwell axle shaft. Some serious meat there and i don't know of anybody destroying a Rockwell u-joint. The axle shafts were upgraded to Ouverson Chromoly shafts so that should hold up.

I ordered seals and bearings and started to overhaul the axles. Here is the center chunk lifted out of the axle.


The 2.5 Rockwell consists of 2 gear pairs, the input shaft as pinion and the ring gear on the intermediate shaft that runs to the right (on this pic), then another gear that drives the bull gear you see on the bottom.

This gives a total of 6.27:1 gear reduction in 2 steps.


Here are the inner parts, on the top left is a Dana 30 Differential, below the intermediate shaft with the gear, to the right the input shaft (pinion), top right the bull gear with the differential carrying the dertroit locker and the ring gear of the intermediate shaft below.

to be continued ...

02-21-2010, 14:22
Your pics do not work..

02-21-2010, 14:23
Its better to upload the pics on this forum

02-21-2010, 14:26
Should work now, had to adjust the viewing rights for the pics.

Pics visible now?

02-21-2010, 15:07
yepp... should be nice to see that rig readdy... I know you for a person how likes it big and powerfull

02-21-2010, 15:11
OK, pics are visible, let's continue :biggrin:

Tommy, this rig is already finished and functional for about 2 years now and was the reason for some rule changing at the VDGV and the Eurotrial, more on that later.

Meanwhile the axles got new seals and new rubber boots.


The knuckles got new bearings and the assembly begins




The hub and the inside of the knuckle are filled with marine grease (2 kg each side).


The hubs are flipped in (check first pic in post 1) to reduce the WMS-WMS width.

This is the finished look, the front axle was not that bad rustwise so i did not sandblast it.


02-21-2010, 15:28
Axles done, let's start with the frame ...

I put the engine and the transmission on blocks and started to build the frame around them after measuring the width with the headers on the engine.


With the axles put in place for the desired wheelbase (300 cm) i started to bend some tubing. All tubing used is 44 x 2,9 mm ST52 seamless.


Motor mounts

I addd a tube to connect the front and read, put some tubing to the side and started building the front.


2 tubes added as seat carriers and seats added i started building the main cage and the rear.




02-21-2010, 15:57
Added some more tubing and considered the frame done.



Next thing was to link the axles and put the shocks in. I decided to get the Sway-A-Way 2.5 air shocks as i like the simplicity of an air shock.


The tires (44" Boggers) are mounted to 12 x 16.5 Stazworks double beadlocks and the axles received their steering cylinders from PSC.



After some sheetmetal work where i took no pictures (i hate welding sheet metal) and the final placement of the radiator, batteries and propane bottles (yes, it ran on propane) i disassembled the vehicle and the frame went out for powdercoating.

02-21-2010, 18:13
very nice work, more pics and tech please :smokin:

02-22-2010, 10:40
Now the next important thing - the brakes.

Rockwells have drum brakes, big, ugly and heavy drum brakes. Putting individual discs was the first thought - but .....

1. you need at least 20" wheels because of the big rotors and calipers

2. with discs you have to flip the hubs to the outside means 2400 mm WMS-WMS :shaking:

3. i wanted to run boggers and the max. size for tires in the VDGV and eurotrial regulations say max. 1250 mm dia. So the max. tire is a 44 and they only come in max. 16.5" wheel dia.

So i decided to run pinion brakes, i have detroit lockers in both axles so the braking force would be evenly distributed on the axle and even if one tire is in the air the other one will still have full stopping power.

So i ordered 2 sets of Ouverson pinion brakes


Those are Wilwood 4 piston Dynalite calipers and with the gear reduction of the differential multiplying the braking force by 6.27 this should be more than enough to stop the vehicle even with 1 brake.

So i used 2 Wilwood 7/8" Master cylinders (1 for each brake)


and 2 brake pedals.


They are really close to each other so if you step on the brakes you will step on both at the same time.

This way i have a true dual brake system so in case one fails i will still have enough stopping power.

02-24-2010, 08:23

As i told you i wanted a big block so i bought a Chevy 454 engine from a guy named Volker Penning (he is the german pendant of Tim Madge as i found out later).


As i did not have any brackets to mount the alternator and the power steering pump i bought a kit from March Performance and a Meziere electric water pump so i could cool down the engine without the need to have it running.



The engine also received a propane system


The advantage of propane is that propane will flow by itself, no pump to go bad, no matter if your vehicle is upside down or on the side. Also it is very simple, you just need a regular distributor, no electronics or computer. As you can see in the last picture i used a HEI distributor.

The day came to fire up the engine and when i filled it with water it ran out of 2 cracks in the engine block. So i bought a junk engine for 3000 EUR :shaking:

To continue with the buggy i bought another stock 454 in the US for about 1500 USD.

Transmission is a TH400HD out of an army pickup.


It received a complete overhaul including a full manual reverse shift kit. So the shift parttern is now P-R-D-1-2-3 and i have to shift all gears by myself. The advantage is that i can shift under full power without power loss in the fraction of a second.

Transfer case is a 2-speed ATLAS II with 3:1 reduction 32 spline 1350 yokes front and rear.

02-24-2010, 17:28
The gauges and switches


On the top left you see the "joystick" to steer the rear axle.

03-05-2010, 17:17
OK, had a lot of work to do, let's continue ......

The frame was out for powdercoating


pearl ruby red :D

Then the assembly began and since it was together before it was a simple job. After a few days the engine and drivetrain was in.


nearly finished, needs a few skins


Added some Makrolon skins (painted from behind so the color does not scratch off)




After a few runs i noticed that the power steering belt was always slipping which generated an annoying noise so i had to change something. I came up with this


With the tooth belts slipping was impossible.

03-05-2010, 18:12
This must be the most awsome rig in germany!!
Good work!:smokin:

03-08-2010, 07:35
Thanks, seems you are right, after my first start at a VDGV event they changed the regulations so i'm not able to compete any more. Thefinger

They changed the regulations of the brakes from "Brakes are free of choice" to "There must be a brake at each tire" and ruled me out by this. Thefinger

03-08-2010, 10:36
hi guys,

of course the sledge hammer is an awsome car. great components....

but there is a big disadvantage:

its to big. with a spider you can drive through the axles....:smokin: (wheelbase 300cm)

to use it in trial the size of the car is to big.

for trophy or monsterrace i think the hammer is quiet good.


03-08-2010, 10:41
... but the story is not finished :shaking:

The 454 i bought was a bit "tired" so i decided to build one (don't want to buy another expensive POS).

Bought a new engine block and stuffed it with a 4.250" stroker crank, H-beams and forged Mahle pistons (+ 10cc Dome) along with a mild hydro roller cam.


I also found some WORLD castings MERLIN cylinder heads :smokin: This raised my compression to 10.8 instead of stock 8.1.


Added some Rhoads hydraulic roller lifters and roller rockers.


Ready to rock


I ran a test on my engine simulator and with the LPG it should put out 460 PS and 860 Nm. As i found out later this was pushing the limits of the LPG system as it could only provide enough for about 500 PS.

03-08-2010, 11:02

03-08-2010, 15:40
hi guys,

of course the sledge hammer is an awsome car. great components....

but there is a big disadvantage:

its to big. with a spider you can drive through the axles....:smokin: (wheelbase 300cm)

to use it in trial the size of the car is to big.

for trophy or monsterrace i think the hammer is quiet good.


you haven't seen this thing in action :smokin: I can guarantee you that it's size doesn't matter. I would like to prove it but i'm not allowed to and changing the brakes is a nono.


This pic is from a free-style-trial which is "famous" for it's tight turns and narrow sections (everything suzuki). I finished 1st with 0 points.

03-08-2010, 15:44
What is the weight of the car??

03-08-2010, 15:45
It weighs in at 1800 kg, the future will see 54" boggers which will raise the weight to 2000 kg.

03-08-2010, 15:48
hmmm... really light compared to the size.... Why 54" Boggers?? The lugs are looking rally small on that tire??

03-08-2010, 15:57
hmmm... really light compared to the size.... Why 54" Boggers?? The lugs are looking rally small on that tire??

The lugs may look small but they are the same size as on the 44s. Why? Because i can :grinpimp:

03-08-2010, 16:02
Here some small vids





As you can see this thing does really tight turns.

03-08-2010, 16:42
As i mentioned before i was pushing the limits with the propane system. The engine got hot and finally died 2 times during a competition. So i decided to pass away from the propane and go fuel injected.

The engine itself ran hot a few times so i decided she needed an overhaul before i would trust it again.

I had a little box standing around that was intended for a different project.



Added a gas tank (RCI fuel cell) in the rear and this is how it looks today.



03-30-2010, 20:24
I like the ramjet

04-21-2010, 16:00
Mounted my new tires (54" boggers) and went out for a test drive :smokin: but i found a weak point :pissed: All 6 bolts that attach the ATLAS to the TH400 were sheared off. Will have to find out what happened and why all 6 bolts broke the same time.

04-21-2010, 16:02
its a big car... and 54 Boogers looked good on it...

04-22-2010, 10:18
Thanks, you will see it in a few months :grinpimp:

At the moment i'm looking for some stronger studs to hold the ATLAS in place.