The Astute is a beautiful 2WD car. It’s very fast on the track but very fragile and it's frustrating how it can break easily if you don't do some work on it to improve strength. I have driven it a lot and made many modifications, so I can share with you my tips.
One of the most fragile parts of the car. You absolutely must have a G4 Super Astute front brace if you want to drive your car for more than some minutes. This part is not an optional, is a must have.
Super Astute front brace, part G4 in picture below.
You can also use Madcap front end that is a little bit stronger but not enough without any brace. Madcap has a front brace but that needs the plastic bathtub chassis to be mounted. You can avoid this problem with a couple of aluminum columns.
Madcap front bulkhead:
Madcap front brace (G3 part). As you can see it need a Madcap plastic bathtub chassis or...
... the columns to adapt the Madcap front brace to a FRP or Carbon plate chassis. I made them myself but the Astute/Egress ones will not work, they are too short. These columns must be 25 mm long. You also must drill two more holes in the chassis to accommodate these two columns.
Madcap and Astute front bulkheads fit very well but they are not identical. Madcap one is longer on front to accommodate the larger bumper but this is not a problem. Astute mini bumper will fit without problems. The major difference is the front arms offset that is some millimeter back on the Madcap. This is not a big problem again. If you have dampers on ball connectors the problem doesn't exist, your dampers will be a little bit more inclined. If you have dampers on bushing you will need longer bushing on top mount. The length of the car will be shorter obviously if you will use Astute uprights. With Madcap bulkhead you need also Madcap uprights to keep the same wheelbase. The Madcap bulkhead is lighter and doesn't need the 730 bushings or 730 ball bearings.
Differences between bulkheads:
Another modification for the Astute is the front arms swap with Madcap ones. Astute and Madcap front arms are almost identical in width and length. The only good reason to swap them is the lack of Astute spares.
There are only few differences between the two arms. Damper position is different. Both arms have 3 damper holes but on Madcap they located closer to the bulkhead, so Madcap middle hole is Astute inner hole. Another difference is the offset. On the Madcap arms the damper mount is more in front compared to the Astute one to compensate the different arm offset on the bulkhead. The result is that if you mount a Madcap front arm on the Astute bulkhead the dampers will be more inclined forward in the lower mount and the wheelbase will remain identical.
If you mount a Madcap arm on the Madcap bulkhead the dampers will be not inclined but you must use the Madcap Uprights also or the wheelbase will be shorter. In fact Astute Uprights have the wheel axle some millimeter back to compensate the different C-Hub offset in the Astute and keep the same wheelbase.
Super Astute arms are another thing. Astute upright have the wheel axle back like the shopping carts. This allows keeping the straight direction of the car. After the release of the Astute, Tamiya made the Madcap with different bulkhead, front arms and uprights.
In the Madcap the traditional Hornet uprights have the wheel axle in the same position of the steering axle. The wheelbase is equal to Astute but the geometries of front upright are different. With the Super Astute Tamiya decided to keep the Astute bulkhead and the Madcap wheel base together. A new design is for Super Astute arms, with the correct offset for the dampers and more inner holes to increase wheel travel and car height. But the Super Astute arm curves back to obtain the same wheelbase as the Madcap. This allows using normal uprights without wheel axle offset back.
You can also use (with Astute arms) optional black Uprights for the Formula chassis that have a similar shape of the Madcap Uprights but same Astute Uprights offset.
In my opinion the best choice for the Astute is the Super Astute arms that are stronger and keep the normal uprights. Madcap arms are lighter than Astute ones but are softer and flex a lot so there is no advantage to mount them.
Differences between arms shape and dampers position:
Correct position of the arms on their own bulkheads:
Front uprights and C-Hubs
As you can see in the pictures Astute front C-Hubs are crazy complicated and heavy with a total of twelve 730 ball bearings (or bushings). Madcap C-Hubs are the right solution but you can not mount Astute Uprights on Madcap C-Hubs. Keep in mind that Astute upright have a different wheel offset. This is compensated by the different bulkhead in the Madcap or the different shape in the Super Astute arms if you want to maintain the same wheel base. The solution to mantain the original geometry is again the F104 black optional uprights that have some offset like Astute original uprights.
The best solution in my opinion is Super Astute front arms and bulkheads with front brace, Madcap C-Hub and Super Astute/Dyna Storm uprights (you must file them to fit into the Madcap C-Hub).
Madcap C-Hubs are lighter, simpler and allow a normal upper arm with 5 mm ball connector.
Super Astute upright have the same wheel offset than Madcap but a longer arm that allows a more precise responding in the drive.
Astute over engineered front C-Hubs and Upright:
Madcap simpler C-Hubs and Upright. These C-Hubs allow simple upper arms with 5 mm ball connectors:
Different wheel offset in the uprights. Note Astute wheel position:
Basically the wheelbase on all cars is the same.
Astute has bulkhead arms position forward and wheel offset back.
Madcap has bulkhead arms position back and zero wheel offset.
Super Astute has bulkhead arms position forward and zero wheel offset. To maintain the same wheelbase the arms are curved back.
If you want to fit Super Astute/Dyna Storm steering arms on Madcap C-Hubs you must file the white part of the arms. Original Madcap Steering arms are 11 millimeters high, Super Astute are 13 millimeters so no direct fit. A little bit of work is needed to bring the Super Astute pieces to 11 mm.
Written by TB member Massimo Kontemax Russo, TB user Kontemax