The Mazda B2500 Turbodiesel 4x4 Brush Bumper Project

The Mazda B2500 Turbodiesel 4x4 I've been driving is great for the offroading I have to do out on the land - but it has it's peculiarities. One of these peculiarities is the turbo intercooler, which seems to have been an afterthought instead of a part of the design. The 2.5L engine does well with the turbo; there is some turbo lag but it isn't a large turbo so the lag is fairly easy to compensate for - though it takes some getting used to on curvy hillside roads if you're used to using compression braking with the manual transmission.

I am constantly reminded by people in front of me that there are people who don't understand compression braking.

Even so, when pounding through the brush at 5-15 km/hr, the intercooler is at risk because, for some reason, Mazda engineers didn't seem to think that a Mazda 2.5L turbodiesel 4x4 would... ever go out in the brush. And so it has the street bumper with the flimsy plastic undermount that may streamline the truck aerodynamically in an extremely minimal fashion. On the road, it works well. And to it's credit (and my own disbelief), it does work out fairly well in tall grass. It does not, however, do well in guava patches and against - as I recently found out - the remains of trees hidden by the tall grass. The clips pop off, the license plate (mounted on plastic to plastic) flies below, and the intercooler can get damaged.

Funny story. Sort of.

Some surveyors were doing some work, and needed a line through the brush. A surveyor's assistant, clearing the area, had been stung by some errant jack spaniards (local term for paper wasps). I offered to flatten some of the brush with the truck - after all, I had just lost the license plate in a guava patch. What more could go wrong?

So I eased the truck through, to a point (windows up of course) and felt a bump. The truck's in 4x2, so I switch over to 4x4 High. No movement forward. 4x4 low. No movement forward. Back out, rocking it. No way forward. Back out. Bear in mind all of this is being done gently, or as gently as possible. If you have to force the truck somewhere, it's very likely you'll have to force it out. So if you don't want to force it out... don't force it in. If more people understood this, the use of chains would decrease significantly.

On inspection, the plastic underlining of the front bumper was hanging on for dear life. All clips were broken. A walk out into the brush, warily, revealed a tree that T&TEC had cut down at the perfect height not to be seen. The truck could have gone over it, but if it had the intercooler would probably have been ripped off - and that falls under 'not good'. As it was, the intercooler got crushed a bit, but remained functional.

Meanwhile, someone who lives nearby - who witnessed the whole thing, from the surveyor being stung to the end, said as I inspected the damage... 'You know, T&TEC chopped down a mango tree there...'

Thanks.

Thus began the...

Great Bumper Search

There are places that sell off road bumpers here in Trinidad and Tobago, though most of them aren't actually for offroad. They're mainly bling - things that look pretty and will crumple nicely under a bit of pressure, possibly doing more body damage than would be possible without them. Other, more solid bumpers are also available - but they are the standard brush guards that are seen for offroading where trees and large rocks you can see are more of a problem. As a general rule, if I can see it I can avoid it. It's what I can't see that bothers me. Plus, all the bumpers aren't really designed for the brush that I encounter just about every day - tall donkey grass, bull grass, the amazingly versatile guava patches, and so forth. These strip polish and paint over time, and the broken guava branches can put things at risk for puncture. Guava wood is annoyingly tough at times - not to mention sharp and pointy. And the plastic clip on would still be at risk as well.

And none of the bumpers available accomodate that. The answer, therefore, was to start designing and making my own bumper with the help of Boya, a welder in the employ of an Uncle.

Design Criteria

The design criteria are pretty simple: (1) Protect the intercooler. (2) Stand up to abuse. (3) Allow airflow to the Intercooler. (4) Bolt on, bolt off. (5) Be as light as possible.

The Stuff

For the project, I got 20' of 1" Galvanize Pipe, 2 U-Bolts to fit for the pipe mounting to the chassis (it so happens 1" wide is a fit), 8 Pin rubbers (between the Chassis Mount and the pipe, and a sheet of 16 gauge steel.

The design mimics the classic brushguard where the tow mounts below are attached to, but it also attaches to the front chassis where the front bumper used to be. The picture above shows the skeleton of the framework, done first to allow us to bend pipe to fit the tow mounts.

Progress

Still a work in progress, the basic framework is already set up. The rod between the two tow mount supports is temporary while we finish curving the steel sheet.

The sheet is already properly tacked to the bars (after this photo was taken).

The sides still need to be bent inward to allow for some lateral strength, but as far as forward strength - I'm sure it can handle a guava patch or, perhaps even a few guava trees if necessary. A heavier bumper would remove all doubts, but the weight just doesn't make sense for the requirements.

What's Left

Between Monday and Tuesday, I expect it will be done and coated with undercoating (which I can easily use to touch up after fun in the brush). In that time, steel sheet will be bent to mold to the body at the top and sides.

Air to the intercooler will be provided for by some holes drilled in the stainless sheet. I'm considering a design for that, but will probably end up with a simple square pattern that won't seriously deteriorate the tensile strength of the bumper while providing airflow to the turbo.

And for highway driving (paved roads), I'm considering a ram air flow to the intercooler from the top of the bumper between the top chassis mounts. Depending on the space available under the bumper, I may try to track down a larger intercooler.

For the Mazda the stockplastic underlining of the bumper costs $1,200 TT (roughly $200 US). And the parts so far for the bumper which replaces that as well as the OEM bumper, and protects the intercooler... is less than $100 US at this point ($520 TT: $82.53 US).

The Intercooler costs $3,500 TT - or $555 US. Do the math.

Random Notes on Offroading in Trinidad and Tobago

There are offroad clubs in Trinidad and Tobago that I don't belong to - offroading to me is practical and not necessarily a hobby... though it is fun. I have a few stories, as every offroad person does, but at the end of the day this is all very much a pragmatic exercise. I don't need to lift the truck further; switching to 18 inch wheels gave enough clearance. I don't want a different 4x4; an old time Land Rover would probably be perfect and the older models of the Toyota pickups have better axles for offroading... but at the end of the day, I don't have those things and they are becoming increasingly rare commodities.

The new pickups rolling out of Japan and Detroit have body designs at the front which, honestly, make me wonder if the engineers actually think 4x4s will go offroad at any point. And most of the vehicles are too wide to be useful, including the new Land Rovers.

Then there is the issue of price of the vehicle, price of the parts, etc.

It would be nice for someone to actually build something meant for offroad again. This plastic stuff is cheap and great for the urban soccer Mom, but hey - can't we have a 'Crazy Uncle' option on these vehicles? Some of us are willing to pay more up front to pay less over time.

Oh, and Mazda? Love your stuff, really. I'm a Rotary afficionado, and love the B2500 TD 4x4. But tell your engineers and salespeople to stop smoking crack when it comes to protecting the intercooler, OK?