My Top Force (PUM)

[Pata76 501]

Hello all! 

Let me present my Top Force PUM carpet racer. 

It is created by my friend Peter hense the name (PUM) 😃

I think he is around this forum too. 

Here goes anyway. 

 

 

Regards Patrik 

[Jonathon Gillham 4605]

Very nice!

Are they off the shelf parts or a lot of custom stuff? It looks like its been strengthened everywhere. The steering is interesting, I don't rate the plastic setup on the Top Force as it seems like it could be a weak spot but hadn't considered carbon

[Pata76 501]

22 minutes ago, Jonathon Gillham said:

Very nice!

Are they off the shelf parts or a lot of custom stuff? It looks like its been strengthened everywhere. The steering is interesting, I don't rate the plastic setup on the Top Force as it seems like it could be a weak spot but hadn't considered carbon

Its only customparts. 

[Superluminal 3750]

I like what youve done with the rear shock tower! Should reduce the chance of breaking the rear gearbox case.

[Pata76 501]

It even has a sliding motormount to be able to use bigger pinions. 

[Grotty Otty 868]

That's brilliant. Probably what the EVO should've been! 

Edited July 28, 2021 by Grotty Otty
Looked sweary when it wasn't.

[djmcnz 754]

Jeepers, there's a lot to unpack there. How about you describe it all, including the development process!

I'm immediately interested in the the rear gearbox reinforcements and the rear chassis extension and matching arms, carbon steering looks nice too.

But we actually want to hear about it all.

[Pata76 501]

27 minutes ago, djmcnz said:

Jeepers, there's a lot to unpack there. How about you describe it all, including the development process!

I'm immediately interested in the the rear gearbox reinforcements and the rear chassis extension and matching arms, carbon steering looks nice too.

But we actually want to hear about it all.

Im going to invite the creator to help me out to answer the questions 😃

[pUs 311]

20 hours ago, djmcnz said:

Jeepers, there's a lot to unpack there. How about you describe it all, including the development process!

I'm immediately interested in the the rear gearbox reinforcements and the rear chassis extension and matching arms, carbon steering looks nice too.

But we actually want to hear about it all.

Well it's a long story. I did a thread about my car in the Top Force & Relatives-group on Facebook and I'll try and paste that text here as well. But basically I wanted to improve the TF a bit for indoor vintage racing. At least in Sweden, the starting fields aren't huge so we can't divide the cars into too many year groups. Which means the Top Force is racing Cat 2000 EC's, Losi XX-4's, Yokomo YZ-10/MX4's etc. I find it slightly unfair but that's just the way it is  There's nothing revolutionary about it, just improving rigidity, moving stuff away from the rear gearbox and lowering the CG.

I tried to use as much std tamiya parts as possible except for all carbon (CNCd by a friend) and the motor mount. Chassis has the same basic dimensions as the kit except for the rear where I have made space for a TR15T/Dyna blaster rear bulkhead setup. Reason for this is to let the suspension be mounted on the chassis instead of the gearbox to offload the whole assembly. Chassis also extends around the motor to let it sit lower and there's actually quite a big difference compared to the std car. The small rear top deck also moves the damper mount away from the gearbox so it's no longer a stressed member of the car. I use re-re Avante aluminium pieces to mount it. The steering arms are 3-piece layered carbon, got so sick and tired of breaking the std ones. I also did another option with more ackermann effect.

The motor mount is also a big deviation, it's not for looks but serves three purposes. 1 - moving the motor away from the gearbox to take even more strain off the assembly. 2 - lowering the CG considerably. 3 - Since it sits lower it requires bigger pinions. I can now use up to 29T together with a 74T spur which enables me to run readily available stuff instead of the speed tuned gear set (we have a 13.5T motor limit for vintage racing). Manobet custom machined it for my chassis and simply did an awesome job, it's more or less based on a sloppy pencil concept drawings and a spare chassis I sent him.. 

As it is now only mine and Patriks car exists. I generally won't sell the conversion even though I have plenty of parts available, the cost for all the custom parts makes the prospect quite unattractive  I'm happy with the car on track though, it feels a bit less sloppy and more precise. Some like it and others feel it's no longer a Top Force, but except for the carbon and motor mount all the hardware on the car is actually Tamiya.
 

[pUs 311]

Pasting the text I wrote up last year (this is my particular runner):

----

Since July last year I’ve been working on improvements for the Top Force specifically for indoor carpet racing. Main focus has been to increase its reliability and competitiveness against slightly more modern cars in vintage racing (XX-4, Cat SE/98 etc) but still keep the vintage spirit intact. With very few exceptions, if any, all concepts seen on this car were also around back in 92/93/94 - a few on other cars, others in the form of prototype stuff. Even the fully adjustable motor mount concept was done by TRF to a few team drivers back then. But anyway..

 

Main targets;

• Increase rear stiffness (damper mount)
• Improve reliability and strain the whole rear gearbox assembly a lot less (cooling, landings, suspension, carrying weight of motor..). Stronger steering arms.
• Lower CoG where possible
• Improve cooling
• Achieve increased rear-toe in and anti-squat without altering position of rear gearbox
• Make the HS gear set redundant (use 74T spur while keeping correct gear ratio)
• Increased tuning options (ackermann option, longer wheelbase option, flex options)
• A compact but effective front anti roll bar solution

 

Did several iterations of the carbon parts and tried a few variations of the motor mount and after tests finally settled on the design you see on the pictures. I originally had big plans also for the front end (411X suspension etc) but that in my mind would have made it drift away too much from what it's supposed to be. As it is now, to me it’s still a Top Force, just a bit refined. On the track it's nice to drive, rolls less and generally runs flatter. It feels more solid, particularly in the rear. In back-to-back comparison with a "standard" Evo (standard as in normal rear gearbox/suspension) on the same track the LCG car could clearly be pushed harder. The difference is not like night and day, car just feels slightly more precise and planted.

 

Full specs;

• Forward + right mounted servo
• Std top force front end
• Manobet front bulkhead
• DSRCC top force arms
• DSRCC titanium hinge pins
• Custom carbon steering arms
• Borivoje brass front brace with custom anti roll bar
• TA-03 type ball diff with hardened outdrives
• Aluminium gearbox plate with grub screws for hinge pins
• Custom LCG carbon damper mount
• Tamiya sleeved dampers, TRF gold shafts
   
• Custom LCG carbon chassis, 2.5 or 3 mm, alternate rear arm mount points for std or extended wheelbase 
• Optional middle post
• Aluminium rear one-piece deck post+mounts
   
• Manobet custom designed LCG sliding aluminium motor mount
• Std TF 74T spur (up to 30T pinion with LCG mount!
• RW drive gear + idler gears
• Std gearbox with cut away motor part + suspension mounts
• Nick Walker lipo brace
   
• TR15T/Dyna Blaster suspension mount geometry (moves shocks further outwards while keeping normal arm length)
• Borivoje aluminium braces for gearbox
• Rear DSRCC super astute arms
• DSRCC titanium hinge pins
• Takis Pallas nylon custom machined suspension bushings
• TR15T suspension mounts
• Super Astute hub carriers
• Avante re-re damper mount hardware
• Custom rear carbon sub-assembly top plate
• Custom LCG carbon damper mount
• Tamiya sleeved dampers, TRF gold shafts
• Manta ray gear differential with hardened outdrives

 

The original goal was to race it at the euro rc masters, but unfortunately I couldn’t attend. If there is any meeting in 2021 I’ll do my best to get there.

Lots of clever people been involved in the making of this, sometimes I’ve felt more like a simple project manager than anything else.. thanks goes to, in no particular order:

 

Borivoje Radicevic

Nick Walker

Takis Pallas

Stefan Larsson (not in group)

Manobet (not in group)

DSRCC 

Brybbair for paint

Thanks also to Patrik Kenne for always being positive and having brought inspiration through the creation of this group, appreciate it!

[pUs 311]

[djmcnz 754]

That my friend is amazing work, and thank you very much for taking the time to describe the vehicle in so much detail, I really appreciate that. 

I used to race these in the early to mid 90's and I can understand all of the changes you've made and all of the reasons you describe. It's quite the amazing feat that you've pulled it all together in such a beautiful fashion that still respects the legacy of the DF01 chassis. Well done. 💪 

[pUs 311]

Thanks, appreciate it! I forgot to add that there are two types of motor mounts as can be seen on that last pic. One has an angled/normal setup which can be used for a normal Top Force chassis without motor cutout and is basically a copy of an old hand made TRF mount that a few team drivers used back in 1992. Original plan was to just use that one, but we realised quite early on that the sliding solution actually works better and is easier to adjust as well.

I think there's another version of that sliding type on CAD file where the motor just clears the std chassis. I have thought about having a 3D-printed cover for the spur/pinion made so that this could be used outdoors too, but haven't really got that far yet.

[Silver-Can 402]

Bravo sir, bravo 👏 .

Very well thought-out and brilliantly executed design enhancements. Another fabulous example of why I'll always love this hobby. I can only dream of this level of craftsmanship, but seeing this, as well as other peoples excellent work (such truck norris' excellent body sets) just boggles my mind.