XR311 Combat Support Vehicle

This is a second hand model I bought from a member on Vintage-RC forum. Given its age and crazy prices for new in box XR311s, it could only be a second hand despite of the limited re-release Tamiya did in 2000.

The XR311 date was originally born in 1977: this is Tamiya's fourth RC model and their first off-road vehicle. Mine is the 2000 re-release, but differences from the 30 years old original model are very few. This replica of an american army vehicle is a true model in motion. The bodyshell is exactly the same as per 1977 and I should drive it very carefully not to avoid damaging it.

The XR311 family

Only two models use this plateform, both being very high detailed off-roader that are much appreciated by collectors around the world.

58004 - XR311 Combat Support Vehicle
58007 - Lamborghini Cheetah

Two videos to present these models, one from the late 70's and a splendid one made by TamOR.

The XR311 promotional video circa 1976-1977 (© Tamiya)

The Lamborghini Cheetah owned by TamOR from Tamiyaclub (© TamOR)

These two models share the same chassis appart from a slightly shorter wheelbase on the Cheetah. The mechanical speed controller is more progressive on the Cheetah and features a reverse gear the XR311 lacks. The XR311 re-release in 2000 featured new metal torsion bars to replace the fragile plastic one of the original release.

When it arrived

My XR311 arrived in a state of the art packaging, but partially disassembled both to protect it during shipping, and because the bodyshell assembly wasn't finished by its previous owner.

The main parts Detail on the windshield

Pilot details: with an helmet for the XR311, without for the Cheetah The chassis

One thing for sure: this model never ran. Everything already assembled was done close to perfection, and the painting job is remarkable with a splendid sand effect: the windshield photo shows the very high painting quality that can be found all around the rest of the bodyshell. That's a shame the excellent painting job could not be finished since I will have to complete it: not sure I can reach such a high skill.

There are many parts remaining to be glued on the bodyshell, the pilot is to be painted and the electronics need to be installed. Finishing this model wil probably take many many hours.

I will not make any change to this model since I consider there no need for it. I thought I could replace the metal bearings with ball bearings, but I decided I won't: first because metal bearings do not wear that much, and second because this model will not run very often due to the extreme fragility of the bodyshell. Loosing a single part on it should be a definitive loss otherwise my banker would suicide himself: not that I love my banker that much, but still . I will install an electronic speed controller because it is more progressive than a mechanical unit and also because there's not much room left on the chassis: modern stick packs are quite longer than dry cells or hump back packs used back in the late 70's. You can't fit the mechanical speed controller and its servo while using a modern stick pack.

The chassis

This is a step not requiring a lot of efforts: only to install the sterring servo, a receiver and the electronic speed controller. Most complicated would be to correctly tie the cables. Well, this was the general idea: doing it revealed to be a little bit more complicated than expected...

First, installing the electronic speed controller (TEU-101BK) and the receiver is not that simple since the holders they are meant to be installed in have a strange shape. But placing a wood wedge and using double-sided tape just solves the problem. Cabling tieing is not very difficult if you think about it first and always remember that the bodyshell closely fits the chassis central frame.

The steering servo is easily fitted with double-sided tape into its place, but doesn't let you fix it better. The servo saver concept was not invented yet so the only way to preserve the servo from shocks was to let it unscratch from the chassis. I decided to reinforce this by fitting a piece of foam to fill the gap: this way, I hope the servo will be better fitted and I won't risk to loose the steering control.

All cables tied and chassis ready to go

The foam to reinforce the steering servo stay

During the assembly process, I noticed a problem with the rear suspension: the default setup was way to soft. So I got the pleasure to discover how torsion bars work. Even if the manual is very clear about it, tuning the suspension is pretty difficult for a human being who only has two hands , especially because the setup must be the same for the two wheels. With calm and patience you can do it, but you'd better find the correct setup at the first try. On mine, I found that a 1/3rd turn setup was the best choice.

The rear drivetrain torsion bars

Alternative suspension idea

To setup up the suspension, you need to turn the black stopper (on the left) and refit it while applying the desired torsion on the bar itself. It seems easy to do, but quite delicate to perform. The first photo shows the re-released XR311 metal torsion bars: they are the same on the original version, but the torsion bars are in plastic.

These original torsion bars tend to wear quickly so most of the original XR311s that managed to time travel till our days have a problem with them. When searching for information on this model, I found a very interesting suspension alternative made by a Tamiyaclub member. OK, remember the solution but forget the blue anodised dampers that really don't fit the model general look.

The bodyshell

This is the most complex bodyshell I have ever seen in RC modeling: it is a very high detailed static model, nothing else. Dozens of parts, most of them being very small, are to be glued on it: these will undoubtely suffer from running conditions. Not even considering possible shocks or any stupid jump attempt, running vibrations will do stress the glue that holds them. From meshes on the motor boot to the front lights, the whippers or the mirrors, the list of possible candidates to be lost while running is long... very long.

Furthermore, the bodyshell on my XR311 got cared by its prvious owner who performed a splendid paint job on it, unformtunetly he never finished it.

First step, painting the pilot, and first surprise: the arms need to be very carefully glued as the hands are meant to hold the steering wheel. Easy to say, but you'll need several tries to find the correct angles. Then painting. You'll need a very thin brush, a black pen for details, a cutter knife blade in order to place paint drops on it and reach those unreachable places. But most of all, you'll need time... a lot of time and patience. Painting a pilot like Albert Attaboy takes about an hour: I spent 4 hours for the XR311 pilot.

1st paint try: too light

Second try a little darker

But the pilot is the easiest to make compared to the bodyshell in itself: I just spent days making tries, glueing parts, unglueing et re-glueing to better fit them. There are so many details that you can't hardly see any difference after working an hour long. But the moment when everything is assembled and glued finally arises: the last part to fit is the roof. I should be the last since one you fit it, you can't access anything else in the cockpit and to the front body fixes.

After hours and days...

Cockpit detail

Motor boot detail

Rear view, the alternative antenna pipe location

I am very pleased with the final result: the perfect paint job performed by the previous owner is the key of that perfect result. To provide even more realism, I just move to the antenna pipe to the rear of the bodyshell: it undoubtely takes more time to pass the antenna wire, but I think it's better this way. Anyway, the bodyshell is such a pain to fit on the chassis that spending a few additionnal minutes passing the antenna wire this way is no big deal at all .

One question remains: does this over 30 years old piece of history run, and better said, how does this run? What about the bodyshell on which so many hours have been spent: will it resist?

First run

Running an XR311 can't be improvised: of course, you'd better take care where to drive and check the sky before leaving, but most of all, you'd better carefully prepare the model before. Once the bodyshell is fitted on the chassis, forget the idea of accessing anything inside like the electronics or the stick pack connector. Once on the track, you should only have to set the switch "on" as the body is quite painful to fit: being so fragile, it is not wise to even consider maniplating the model once there.

So that first run occured on a large parking lot made of gravel. The track was just made by placing cones and no obstacles were in the way.
First I carefully take the XR311 off the box where it was secured with foam for transportation to the track, I switch the radio on, same thing on the car switch, I check throttle and steering work fine and careflly place the old lady onto the gravel...

WOW! The general behavior is just astonishing: quite fast, easy to control, the most beautiful is the way the suspension works. The torsion bars concept provides state of the art realism! The XR311 is a very highly detailed and realistic model, but it is also a moving RC model that just behaves like its real counterpart: the suspension work of this model is simply... natural.

I must admit that I was very surprised by its behavior: the lack of differential and those strange torsion bars didn't help me to feel confident before running it. But the result goes far beyond any expectation: the XR311 is sweat and easy to drive, it behaves more than realistic and no matter how long it takes to assemble and paint it, I just love it!
Of course, being that fragile, I drove it differently from any other of my models: forget any performance related idea. We're talking about the pleasure to drive around with a piece of history and to make the most out of the feelings it provides.

To be honnest, I stopped running after 15 to 20 minutes because I wanted to check if all the parts were still there. No bad surprise, just the double-sided tape fitting the roof that is not strong enought. And I will have to think about an alternative solution to fix the front side of the bodyshell to the chassis since the mounts got lost.

As you can see on the photos, the track was very dusty: good for realism and nice pictures, but it now requires a serious cleaning operation 

"Vintage touch" photo by Boo54

A video made by Teamneogordini

Many more photos are on the gallery.

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First publication: october 03, 2009 Last modified: october 03, 2009

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