Project BMP

Page 4

   
 
 

Let's Go Shopping

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Now that the plan was taking shape I had a good idea of what I needed to purchase for Project BMP.  This is actually a pretty fun portion of the project, I mean who doesn't like to find presents on the doorstep? Ok, so maybe the fun wears off when the Visa bill arrives, but at least you have a pile of shiny parts.  I sat down early on and made a spreadsheet to track the costs and time on this project.  First up was figuring out what I would use from my old crawler.  If the parts were fairly new I just used the receipt price, if they were older I guessed at what they might be worth now.  I really didn't need to assign prices but I just know when this is done I will be asked how much did it cost (right after the "how much does it weigh?" question).

Next up is keeping track of what I need.  As I locate parts I usually hyperlink the part to the internet site I am going to buy it from, makes it easy to find when the time has come to order it.  The column on the left is parts purchased to date (including shipping and taxes).  The first couple rows are blank since I have broken even on the parts car that the transmission and t-case came from.  Tubing and the coilovers are on the verge of being ordered so I have them in both columns.

To avoid having to drop a lot of money at once on parts I may not need for weeks I am going to stagger my purchases and bring stuff in only when I am close to needing it.   This will also allow me to watch for sales to maximize my project dollars.  What I haven't shown in the pictures above is the list of parts I would like to buy if I have money left over, so there is some incentive to keep costs down.

  On to phase 1.  Basically I want to build the base of the buggy and get the drive train mounted to it.   This explains all the drive train parts I have on order.  Coming from Rock4xfabrication is a Ringr transmission adapter, a modified Celica 1970-71 clutch disc (machined 3/8" smaller), a modified Sidekick throwout bearing (the bore is opened up to fit the Toyota transmission snout) and a Sidekick pilot bearing.  From Marlin Crawler I ordered a dual case adapter.  There is a cheaper alternative to the Marlin Adapter but after reading about some of the differences there is no way I'd use the cheaper one especially considering the difference in price is well under $100 or in my case about $15 due to a sale. To complete the drive train I have a Sidekick 4x4 bellhousing coming from Hawk Strictly Suzuki and a pressure plate from Checker Auto Parts. 

Tubing is next up on the to buy list (all but the 1" dia stuff is DOM).  I plan on buying it all at once in order to get a discount.  As you can see, steel prices are still pretty high, roughly double what I paid two years ago.  I will also swap out all my 1.38 x .120 wall tubing for 1.50 x .095 wall tubing to save weight and to cut down on the number of tools I will need (more on that below). 

I put the 1.38 x .120 tubing in my design to save some weight.  It was going to be used for bracing in areas not expected to take rock hits but out of curiosity I played around with the tubing  in the FEA software we have at work.  I modeled a 36" long piece of DOM tubing, constrained it at both ends, then applied a 3000lb load to the middle of it in one direction.  This would simulate a slow roll, a fast roll would easily multiply that force value.  Here is the estimated amount of deflection each material would see:

1.375 OD X .120 Wall = .26in

1.50 OD X .095 Wall = .24in

1.50 OD X .120 Wall = .19in

As you can see there wasn't a huge difference between any of the materials.  Assuming good welds on the ends, the tubing would most likely dent.  Knowing this I am going to replace all the 1 3/8 braces with 1.50 x .095 wall tubing.  This will save a little weight and eliminate the need to buy 1 3/8 hole saws.

Eliminating all the 1 3/8 tubing also means I only have to buy one of these tools.  It's called a Pipemaster, available from Trick-Tools.com in a variety of sizes and are designed to make notching tubes at odd angles much easier. Basically you position the two tubes in relation to each other, slide the pipemaster over the tube that needs notching and then slide it down till the metal pins form the shape of the other tube, this gives you the profile of the required notch.  You can then transfer this profile to the tube that needs to be notched.  If this little tool works good it will save me a lot of time.

The other tool I picked up from Trick-tools is a pair of these tube welding positioners.  Hopefully they'll be as valuable as a second set of hands.

Update 7-31-04

I have begun the tear down of the old rig.  The first thing I did today was to pull all my tools and spare parts out to weigh them and then put them away.  I ended up pulling out 212lbs of gear broken down as follows:

Item Weight (lbs)
 
Tool Bag 18.50
Large Bag 13.00
Ammo Cans (2) 29.50
Ammo Can (1) 22.00
Spare Axles (3) 35.00
Straps/Air Hose 13.50
Spare Driveshafts 18.00
Intermediate Shaft 7.00
Hi-Lift 27.00
ARB Compressor 7.50
D-Rings 5.00
Spare Link 16.00

I guessed 200-300lbs so I was in the ballpark.  I am hoping to pare down the spare parts in Project BMP, leaving more of the heavy stuff at the trailer unless the remoteness of the trail requires otherwise.

On the design front I have continued to refine the chassis design.  I went through my model today and changed most of the dash bar tubing and the cooler rack tubing to 1.00 x .055 wall.  I also eliminated a some redundant braces and changed the roof shape.  I managed to cut about 50lbs of weight off the chassis bringing it down to 460lbs.  

  

Another change was the decision to go with a set of 16" air shocks instead of purchasing another set of coilovers.  Both economics and the weight savings helped push me in this direction.  From what I have read and heard, the airshocks weigh about 6-8lbs each as opposed to roughly 42lbs for a single coilover shock with dual coils.  That is a huge weight savings.  I have the airshocks slated to go in the rear of the buggy since that will be the lighter end.  This change along with the chassis refinements puts the estimated Project BMP weight at 2574 lbs, down from just over 2800lbs.  I am really happy with this especially since it includes a tire upgrade to some 38 x 15.50 MT Baja Claws. 

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