Tamiya Tyrrell P34 Six Wheeler
Tyrrell P34 Six Wheeler by Black Hole Sun
This is a second hand model in perfect shape despite being 30 years old! This original 1977 release is close to an UFO in the Tamiya range of products, exactly like when its real-size counterpart showed up on Formula 1 tracks at the time. This radical architecture was designed to get a better lift by lowering the front end of the car which offered better frontal downforce. The smaller front wheels diameter reduced grip so the front drivetrain was doubled and thus it offered a greater total contact patch of the front tyres compared to classical designs. This model is unique in Formula 1 history, especially because no other team ever dared to develop such a radical concept... and may be also because rules didn't allow caravans providing aerodynamic features .
So this is a very old model that joins my collection and I'm lucky it is in perfect shape. Despite its advanced age, my Tyrrell P34 Six Wheeler will not stay on a shelf: this car will be driven so that the RS-380 motor can scream when running at full speed in the grid lane...
The Tyrrell P34 Six Wheeler family
Even being very specific to this model, the chassis is mostly based on the one found on Tamiya's first two models. Most importantly, it is the start of the first Formula 1 model series until 1982. In addition, Tamiya released a limited edition of this bodyshell on the F-103RS chassis in 2000 to celebrate the real car victory in the Historic Formula 1 championship that same year.
|58003 Tyrrell P34 Six Wheeler (1977)
|49154 Tyrrell P34 Six Wheeler (2000)
||The modified F-103RS chassis
No other model uses the 1977 original Tyrrell P34 Six Wheeler chassis. But the modified F-103RS chassis was used for another version of this car:
|84111 Tyrrell P34 Six Wheeler 1976 Japan GP (2009)
As the 84xxx reference shows, this is a limited edition, but the bodyshell is in lexan and not in ABS like the 1977 original and 2000 re-released edtions. Personally, I'm not a fan of this Japan GP version even if the open-air engine makes it look even more realistic.
When it arrived
I bought this model from a fellow collector who owns several versions of this specific Tyrrell P34 because he loves the chassis architecture: I fully agree with him. The model never ran far: it is in perfect shape but the decades left their marks on it.
|My Tyrrell P34 Six Wheeler chassis
The other side
A good cleaning is needed after 3 decades and the white part of the body needs some work as it has yellowed in some places (as you can see on the second cockpit photo). Of course, I will also need to work on the electronic components.
Motor and gears
The motor is that evilish Mabuchi RS-380 stuffed with steroids. Here's a comparision table with the standard 540 motors: the SH version was made by Mabuchi and can be found on almost any Tamiya model until the 90's when it was replaced by Johnson Electric J version we still can find in most modern kits. Please note values are theoretical and given for 7.2V:
Power drain at load (A)
At first sight, the RS-380 rpm value seems correct... except that with so little torque compared to the 540, the RS-380 will struggle to move the car and reach its maximum rpm. Especially since the Tyrrell P34 weights a "ton" (1.4 Kg) with its 6 wheels, its aluminum chassis and its heavy ABS bodyshell. A standard 540 motor gives wings to my Footwork FA13 (1.1 Kg), but I guess the Tyrrell will be much more reasonable... The manual says it all: 26 km/h top speed with 6V cells. With 7.2V cells, the top speed should reach 30 km/h: we'll see that at the first run.
There is an optional 540 type motor mount but I prefer to first test with the original setup. If the car reveals to be too slow, then I'll do my best to find one if it is still available somewhere: anyway, I don't want to make this model fly.
The standard gearing lets you choose between 4 setups: two short ratios (19.4 and 23.3) and two long ratios (5.8 and 7.0). The long ratios can be setup by positionning the motor directly onto the spur gear whereas the short ratios require an additional intermediate gear as shown below:
|Long ratio setup (high top speed)
||Short ratio setup (high torque)
In addition, ratios can vary by inverting the motor pinion position: on the first photo, this is the longest available ratio and the second photo the longest of the short ratios.
The photos also show the planetary differential gear mounted on the rear right wheel: simple and reliable design, this is the ball-differential ancestor that can still be found at the very same place on modern Formula 1 chassis from model 58084 released back in 1990 (some 13 years later).
The very first test run in the loft corridor led to a dramatic conclusion: the steroid-stuffed RS-380 motor can't decently move the 1,400g weight car. The lack of torque is obvious: rear tires will never burn... even on ice . Once in motion, the top speed is so slow that any of my other cars can go much faster in reverse. Hoping this was only due to the longest gear ratio, I reverted the motor pinion to go for the shortest I can set on the car (since I don't have the intermediate gear): the car starts much faster... at the start. Unfortunately, performances are low, not to say ridiculous: any straight line longer than 10 meters will make any driver have a nap until the car reaches at least the break point for the next corner.
The conclusion is easy: either my motor is almsot dead or it has not enough power to decently run this car. Solution is easy too: either I look for a compatible motor with more torque and top speed or I have to find the optional RS-540 motor mount.
I chose to go for the period SP-5023 hop-up that features the motor mount, the RS-540 motor, motor pinions and a fuse for the mechanical speed controller.
|The SP-5023 hop-up
||Once mounted in the chassis
With this new motor mount, I now have two new gear ratios available: 18.64 with the 15T pinion and 13.98 with the 20T pinion. I chose the longest gear ratio for a better top speed in order to see how the chassis performs. But this is also meant to reduce the available power at low speed since I guess this car might behave with a true "vintage touch" that I'll need to cope with if I don't want to risk dangerous stunts on the track.
The central deck
This is the part of the chassis that hosts all the electronic components: the steering servo, throttle servo with its mechanical speed controller featuring a fuse, the battery holder, the receiver and the cells pack. This chassis was designed to accept all three different propulsion pack types from the time, each one delivering 6V:
- 4 dry cells
- 4 NiCad cells
- 1 5 elements 1200maH pack
The manual states that duration of run is about 50 minutes thanks to the low powered Mabuchi RS-380.
Even if I leave my Tyrrell P34 as per its original electronic setup, I will give it modern components so as not to risk any control loss when batteries go low. A new TEU-104BK speed controller will be enough to drive the Mabuchi 540 mpotor. For the batttery pack, the stick shape modern format is a bit too long to fit under the bodyshell: I could have modified a battery pack like I did for my Celica LB Turbo but I don't have any more left to sacrifice for this model.
So I am going to use a modern "hump pack" that Carson had the great idea to release since the Rough Rider and Sand Scorcher were re-released. But my Tyrrell P34 from 1977 was never designed to host it so this will require some chassis modifications. I started with a basic idea: simply put the hump-pack on the radio deck. Unfortunately, it is a few millimeters too high to perfectly fit under the driver cockpit.
|The Hump pack battery
||Fitted on the radio deck
It is only a few millimeters too high, but the bodyshell lies on it and I don't like the idea that this will put constraints on the bodyshell holders. Several options to solve this:
- to relocate everything and to fit a modern battery pack longuitudinally
- to relocate the battery pack behind the deck (where the receiver and speed controller are)
- to remove the deck and fit the battery pack right onto the chassis
- to mod the deck
I didn't choose to radically change the chassis setup since I wanted to stay as close as possible to the original. Neither did I wish to relocate the battery pack to the rear of the chassis: this would also seriously modify the weight distribution to the rear of the chassis that already suffers from understeer.
Remaining options were to remove the deck (but then how do I fix the battery pack?) or to modify the deck. I went for the last solution which is to lower the deck by folding the mounts in order to stick it to the chassis plate. The height clearance is enough and the deck can still be held by the two remaining holders. For the two unused holders, you can either drill the chassis for new mounting points or stick the deck with double sided tape. I chose the last solution.
|Electronics from speed controller side
||Electronics from receiver side
For the rest of electronic setup, the antenna post is located on the left of the bodyshell: no need to wonder where to place the receiver and the speed controller logically goes the other side leaving room in between. It is now rare to have so much room on modern models so I decided to mount the original mechanical speed controller and throttle servo for the "vintage touch". Of course, they are not connected.
Suspension and front drivetrain
At the rear, the suspension is very smart and easy to understand: it doesn't exist. It could be considered that the minimum service could be provided by the chassis natural flexibility... well, no, it was never designed to flex in any way.
In fact, the whole chassis suspension comes out from the front drivetrain. All the steering system is mounted on a metal deck that is fixed onto the main chassis plate. The steering deck fixings include two springs at the front in order for the steering deck to oscillate sideways. In addition, the steering deck and the main chassis frame remain independant which lets them also move longitudinally.
|Front drivetrain suspension
||Suspension at work
The way all this works is basic: everything works using a front unique pivot that uses the front drivetrain like a support for the entire chassis. Stiffness can be setup by compressing the springs. In theory, this system should make the chassis oversteer since the front drivetrain is kept in contact with the ground. In practice, all the weight is at the rear of the chassis and the very small front wheels offer little grip (even being 4): the truth is that this is a chassis with a lot of understeer. I will test the front drivetrain by making it stiffer or looser to see if it changes anything in the overall chassis behaviour.
Now let's go back to the steering itself: it uses quite a complex system due to the 4 front wheels.
|The original steering system
||The modern steering system
On the original version, the steering servo is double-sided taped on its side onto the steering deck. A link moves a bracket located at the front of the steering system. This bracket transforms the steering servo longitudinal movement into a lateral movement towards the front right wheel. This wheel then drives the opposite front left wheel thanks to a link going transversally across the chassis. On both sides of the chassis, each pair of wheels are attached together by links in order to drive the second set of wheels.
This steering system is very complex due to the horizontally mounted steering servo that can't stand due to the lack of clearance under the body nose. If the servo could have been mounted like on the modern version, the steering system would have been much simpler. Most of all, the steering would have tremendously gained precision thanks to less linkage between the different elements. Unfortunately, the suspension pivots do not leave room for this: at the time, technology probably didn't let Tamiya designers integrate the suspension directly into the uprights like they do on modern Formula 1 chassis.
Explaining the original steering complexity and play was done for a reason: as you can see on the photos below, the steering is somewhat elastic and with a variable geometry. Please note that the servo head remained fixed between the two shots:
With so much precision in the steering system, trajectories are obviously... vintage . Well, the Tyrrell P34 is a Formula 1 and therefore should be the very best of the technology at the time, but Tamiya's replica clearly doesn't show the same degree of sophistication. But we have to keep in mind that this model is over 30 years old and that it was only the third model released by the manufacturer: the mechanical challenge of the 4 wheel steering was not that easy to solve for the designers. Anyway, this is an old RC grandma from which you can't expect performances to be compared to modern models. At the time, RC models were mostly models in motion as the highly detailled bodyshell proves.
On my model, the rims show some impacts, but nothing serious. On the other hand, the tires show cracks and were glued the wrong way on the rims which makes it impossible to add tyre-lettering. Even if my Tyrrell P34 could safely run with its original shoes, I prefered to get a complete set of new wheels. These parts are available and easy to find since the new modified F-103RS chassis version wheelset is compatible with the original chassis.
The complete rim set (ref 9334060), the front (ref 9805718) and rear (ref 9805717) tires
Most of all, I wanted to have these parts in stock while they are still available and at reasonable prices since the 2000 re-release. Since my Tyrrell P34 will be run, it's better to anticipate tomorrows needs. Just one detail though: the original rims colour is slightly different from the re-released ones. The dark grey from 1977 became black in 2000, but you'd need to have a very close look to notice.
For tyre-lettering, I used a proven technique but it was the very first time I tried it: take a tooth-pick or a match and use them to place little paint drops into the letters drawings on the tire. The paint being liquid, it will naturally spread into the drawings. This sounds very easy but the art is to find the correct paint drop size. This requires a very close attention and to go very slowly: I spent a full day to paint the whole wheelset both sides.
Editors note: if the lettering is raised you can use a very quick painting technique called "dry brushing" where you wipe most of the paint off of a small paintbrush with a rag and then run the bristles over the raised lettering of the tyre. The paint will stick to the raised areas.
If the result is pretty good on the rear tyres, it is perfect on the much smaller front tyres. For a first try, I'm pretty happy with the result especially since the defaults can't be seen when the car runs.
But adapting re-released front wheels is not a direct fit: on the original version, the wheel axle has a long 4mm screw on which a flanged tube is used as a "flanged bearing" for the rim. A nut without screw thread goes into the rim and spins around the flanged tube (see the second photo below).
On the re-released version, you have real modern 5mm wheel axles (see first picture below). The modern rims need 850 type ball bearings to fit the wheel axle.
To fit the re-released rims on the 1977 original setup, you need 840 type bearings even if they are not the exact same dimensions: an 840 type bearing has an inner 4mm diameter, an outer 8mm diameter and a 3mm thickness. Since 2 bearings are required per wheel, this setup will result in a 1mm positive offset. The wheel axle screw being long enough, this will be no problem.
|Re-released modern front uprights
||The 1977 original setup
||The 840 bearings for modern rims
In the end, I will run my Tyrrell P34 with its original rim set and a new complete tire set, the re-released wheel set being kept as spare.
It is in perfect shape but the white part of the plastic shows the passing of time: it has turned yellow in some places because there is no paint. The stickers are already stuck and to my knowledge, there is no reliable technique to remove them properly in order to re-use them later.
Hopefully a solution is available using repro stickers that you can find at Tamiyoman's on Tamiyaclub for example. His stickers are pretty much exact replicas, they are of excellent quality and are listed at very reasonable prices.
So I could remove any original sticker and detach the white part of the bodyshell. I also detached the driver cockpit in order to refresh the paint and change the decoration since I want my Tyrrell P34 driver to be Patrick Depailler.
Painting is very easy since you only need to spray a primer coat before spraying two coats of white. Let paint dry, apply the new repro stickers and paint the driver.
The original stickers on the blue parts of the bodyshell being already a few decades old, I also replaced them all with the new repro stickers.
After the first run test, I noticed the bodyshell had to cope with many strong vibrations mainly due to the aluminium chassis flex and the front bumper being in a cantilevered position. In fact, the problem is the front bumper moving a lot due to chassis natural flex: track defects make the bumper move a lot and hit the bodyshell.
I don't think it is possible to limit the bumper moving since it would require making the chassis stiffer and this would imply heavy modifications, if they are even possible. The solution is to install a dampening system between the bumper and the bodyshell: this is much easier to make.
The idea is limited to filling the gap between the bumper and the body nose: three foams pieces with double-sided tape. Of course, you'd better limit their thickness in order not to put too much pressure on the front body attachments. Painting the foam parts dark black will make them invisible.
For the first run, I had to use the original wheels since I was still waiting for the required bearing to mount the newer ones. Not being sure 30 year old rubber would provide any grip, I drove carefully.
The very first impression is that this model is pretty fast considering its weight. The steering is very imprecise but all the play between so many links can't make you expect anything different: paradoxically, straight lines are tricky to handle since the steering behavior is much better in curbs. I was also expecting this chassis to understeer a lot but it does not: but I should admit I didn't try to test its grip limits.
After the first lap, something else became obvious: suspension exists, the front drivetrain makes it all, but the bodyshell suffers from heavy vibrations. These are so important that it sounds very worrying as soon as speed increases: I have to think about something to better fit the front of the bodyshell since I don't believe it can bear such a bad treatment for long. I think the new front tires will also help since they are much softer than the original ones.
It's not really possible to compare my Tyrrell P34 with my Footwork FA13 even if both are chassis meant to compete in the same category. Driving my Tyrrell P34 is very similar to driving my XR311 and my Porsche 959: a lot of concentration is required, a lot of care and you always fear to make a lethal mistake for the model. Despite of this, this is a pure pleasure to see such an ancient and out of norm model running.
The following pictures were shot the same day, but my friend Teamneogordini's camera suffered a setup problem on the second photo. But the effect and the shot itself make it look 70's and I see his photo like a vibrant vintage tribute to my model .
RC Formula1 Comment
A great article thanks Pascal! And thanks for providing permission for us to reproduce it in full. You can see the original article in French here (there is also an English version). You can also see more articles on modern and vintage Tamiya RC models (in English and French) on the Black Hole Sun website.
For those of you interested in a P34 on a more modern chassis Top make a hop up for their Rebel F1: TOP Japan > click on Car Kits > click on F1 - 6 wheeler
or contact Rod at TOP Australia and ask him to order it in for you.