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mud4fun

Have things really improved in chassis design?

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A big difference between 10th scale and 1:1 (1th?) is that you can easily overpower a 10th scale car, so drivetrain loss etc is removed from the equation. Slower on the straight? Go from 5.5T to 4.5T or turn up boost. A 2wd mod car will probably run 8.5T - 10.5T depending on grip. A 4wd mod car will run 5.5T - 8.5T depending on grip. Then you have the ESC programming to add in, so 4wd will always be faster in 10th scale.

However, 1989 4wd vs 2020 2wd is an interesting one...

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Well, I have the first set of results in and you're not going to believe this but the Cougar gained a staggering 7 laps on those 1980's style CAT rib spikes on the wet muddy grass, it beat the Thundershot by 1 lap!!!

I am truly shocked by the improvement a change of tyres can make. The rib spikes give amazingly tight turning even under power into a turn.

So here are the results so far:

  • Stagger rib (yellow) no foams - baseline count (worst so far)
  • Cut staggers (silver) no foams - PLUS 1 LAP
  • Mini pins (yellow) with medium foams - PLUS 3 LAPS
  • Rib Spikes (yellow) no foams - PLUS 7 LAPS

Surface was heavily cut up wet muddy grass.

My daughter is swapping the rib spikes onto her DT02 and will be doing another postal race attempt shortly. She was also gobsmacked by the tight turning on the cougar after the tyre change and is hoping for similar gains on the DT02.

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Schumacher U6847, nice find, would be a blast for my Dyna Storm because lokking like the original one. Sadly not available on the Mainland. : (

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Well the DT02 didn't gain any laps so looks like it was already at its limits (and already had tighter turning) whereas it now seems the lack of decent front tyres was holding the Cougar back previously. The Cougar on the U6847's is now turning much tighter than the DT02 despite its much longer wheelbase AND is tracking much better on the straights under power. 

You can now eye up a spot on the lawn, point the Cougar and squirt the throttle and it ends up inch perfect to the point you were aiming for whereas before it was 12" adrift either side. This means I can now maintain precise lines into turns, lap after lap and am able to use more throttle too.

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It took me a while to adapt to the cougar laydown on grass from the cougar KF2se in low grip set up. On carpet it's a a differnet animal!! I think ,horses for courses, is the term. Some people even ran their cougar KD for a while, until they could get a handle on the cougar laydown setup for low grip. I've gone with the ball diff (a must),  brass weighted rear ,under Lipo weight, and ended up with a brass radio plate too! (Then had to reposition the PT, as they don't work on brass....🤦‍♂️), so added weight to be quicker! (But it's low down weight, so actually helps keeping it planted)

Also have a nose weight in the pit box, just incase, plus a pair of glued up U6824 - 2wd front darts.

I use this as a basic guide , Allan runs grass throughout the Scottish nationals, so his setup for a baseline. Michal Orlowski loves his cars with loads of steering, so depends how you drive. 

https://site.petitrc.com/setup/schumacher/setupcougarlaydown/

With saying about me having to get used to the laydown, I wonder if with you knowing your thundershot inside out ,and years of setting it up to your driving style ,helps too? 

I've stopped running 2wd and 4wd at the same event, as I find it takes me a while to get the breaking points etc  ,(breaking too early for 4wd after driving 2wd, and visa versa).

 

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5 hours ago, Jonathon Gillham said:

However, 1989 4wd vs 2020 2wd is an interesting one...

High grip, the 2wd would be quicker, the corner speed is just so much higher these days, the evolution of the cars has been hand in hand with battery and motor tech, weight distribution and power plants and high grip tracks!

Low grip....🤔

 

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14 minutes ago, Wooders28 said:

It took me a while to adapt to the cougar laydown on grass from the cougar KF2se in low grip set up.....

......With saying about me having to get used to the laydown, I wonder if with you knowing your thunderstorm inside out ,and years of setting it up to your driving style ,helps too? 

I've stopped running 2wd and 4wd at the same event, as I find it takes me a while to get the breaking points etc  ,(breaking too early for 4wd after driving 2wd, and visa versa).

 

Thank you!

So true about being used to driving with one chassis type then struggling with another. To be fair, it isn't just going from 2WD to 4WD or vice versa. I have even noticed the problem when going from Thundershot to Egress. It can take an hour of practise before I can get used to the different steering speeds and, like you, the braking points.

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Curious @Wooders28 Allan's spec sheet shows the uncut stagger ribs on the front. That was my slowest tyre. However his was dry grass whereas mine was wet (verging on mud!). So I may find my tyre performance on grass is reversed as we get to summer with the spike rib being slower on dry conditions. 

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10 minutes ago, mud4fun said:

Thank you!

So true about being used to driving with one chassis type then struggling with another. To be fair, it isn't just going from 2WD to 4WD or vice versa. I have even noticed the problem when going from Thundershot to Egress. It can take an hour of practise before I can get used to the different steering speeds and, like you, the braking points.

We had an online Q&A with Michal Orlowski during the first lockdown, and I asked him, "at what point do you stop altering set up, and concentrate on altering your driving style to suit the track or car" , and it couldnt really answer me. 

There's alot to be said for knowing your car, actually takes me a while to get used to the driving the wife's 1:1 car too! 

(I've edited 'thunderstorm ' too...🤦‍♂️)

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@Wooders28 also just noticed, Allan has his front shocks laid down, that was the next thing I was going to try after Trish Neal suggested it increased side bite of front tyres. I may not need it now I have the U6847 tyres which seem to be giving me perfect turning/steering for my driving style but I shall try so I can see what difference it makes.

 

 

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7 hours ago, mud4fun said:

Thanks @DayRider I'm hoping to get out at some point today to start testing. Sadly it was heavy rain here all day yesterday. I have fitted the rib/spike to the Cougar so all ready to go :)

Yes @Mrowka I believe you are correct, logic says on high grip 2WD could be faster BUT the caveat there would be if you can get the power down through two tyres? In theory a 4WD may still be faster even in the dry if running alot of power? I may be wrong though. Will be interesting to see once the warmer dry weather arrives :)

I guess the simple answer is to ask what is faster on tarmac, 2WD or 4WD?

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1 hour ago, mud4fun said:

Curious @Wooders28 Allan's spec sheet shows the uncut stagger ribs on the front. That was my slowest tyre. However his was dry grass whereas mine was wet (verging on mud!). So I may find my tyre performance on grass is reversed as we get to summer with the spike rib being slower on dry conditions. 

 

 

When it turns to mud :-

I use a silver cut stagger. I only use an uncut stagger if the grip is high, stops the car being twitchy. If you have enough steering great. Need more go to a cut.

 

 

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9 hours ago, mud4fun said:

logic says on high grip 2WD could be faster BUT the caveat there would be if you can get the power down through two tyres? In theory a 4WD may still be faster even in the dry if running alot of power?

Getting the power down on high grip isn't an issue, similar to drag racing,  under power the front wheels aren't really on the ground anyway, but with 4wd, you can brake later and get on the power earlier.

 

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While I remember , this is a slowmo of young Daniel, (same driver of the 2wd in the vid with my mid), leading the way in a wet race, turns in earlier, slightly slower, but much much quicker.

 

 

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2 hours ago, Wooders28 said:

While I remember , this is a slowmo of young Daniel, (same driver of the 2wd in the vid with my mid), leading the way in a wet race, turns in earlier, slightly slower, but much much quicker.

 

 

Fab! That track looks like my lawn after 2000 laps of postal racing :D

BTW my cougar now corners on the U6847's as tight (actually tighter) as young Daniels in that vid whereas on the silver cut staggers it cornered as bad as the other buggies running very wide.

The round 7 postal racing track is basically four hairpins, I can now power into those without braking, just lifting off throttle, and pull tight to an 8" diameter rubber marker disk. I actually think I have scope for a couple of more laps to gain yet as I only got 2 runs on the U6847 rib/spikes today. I'm going to laydown the front shocks and do a few more attempts tomorrow. :)

I was also thinking of fitting the narrow Schumacher twin stud tyres (U6797) or mini spikes in green compound (U6550) to the front of the Thundershot, I'm thinking narrower tyres, even on the 4WD may give better turning in very muddy conditions.

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I should clarify that my Thundershot is not standard. In addition to being upgraded to Terra Scorcher spec, it also has turnbuckle steering arms, a lightened and lowered chassis with squared off battery tunnel, bespoke shorter shocks, is running 2.2" wheels and Schumacher race spec tyres. The entire chassis is ballraced using very high quality bearings that are re-oiled every few months and the gears and shafts are all filed, sanded and polished to remove all burrs and distortions and the axles, suspension arms and hub carriers are shimmed to remove slop. The toe in and camber are far from factory spec, they are my own settings from experience in use.

The switch to a very lightweight 4000mah square section LiPo pack transformed the weight distribution and balance of the chassis. Being transverse mounted a heavy NiCd caused problematic cornering and erratic high speed handling. Since switching to a LiPo which is 150g lighter than the previous 8.4v NiCd the front to back weight distribution is nearly 50/50 and side to side is also near 50/50. The car now handles far superior to before. 

In comparison, switching to LiPo from 8.4v NiCd on the Avante2001/Egress caused issues. The Avante2001 has a longitudinal battery placement but in an offset position. The weight distribution actually got worse both front to back and side to side after switching to LiPo because the weight was no longer spread across the length of the car AND the lighter LiPo no longer compensates for the heavy motor and steering servo, made doubly worse by switching to a very light HW1060 ESC instead of the heavy Novak Rooster on the right side of the chassis. The Avante2001 is now heavier at the back and heavier on the motor side of the chassis. This leads to erratic cornering and poorer handling and very poor jumping. It used to jump flat but now it dips to the left when jumping and will not land flat. It no longer corners as well either. Yes, these can be compensated for using balance weights but that negates the weight saving of LiPo and results in a buggy that is significantly heavier and slower than the Thundershot using the same LiPo/Motor/ESC.

On very short twisty tracks the Thundershot beats the Avante2001/Egress every time, possibly due to shorter wheelbase but also due to being 100g lighter in race conditions using same battery, ESC and motor. The Avante/Egress only beats the Thundershot on very long fast tracks on smooth tarmac and even then it is only by fractions of a second.

The Cougar laydown is clearly designed from the outset to use LiPo and jumps flat, has excellent cornering and handling and despite being 2WD has a weight distribution front to back almost equal to the Avante/Egress (on LiPo) albeit inferior to my modified Thundershot.

 

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Well, the winner of the front tyre test on the cougar is the U6550 mini spike (in green compound). I could achieve the tightest turns under power on the wet muddy grass while maintaining good directional stability. It was very close between U6550 and U6847 rib/spike but I personally preferred the grip of U6550 mini spikes however they occasionally snatched and caused me to have to correct a line whereas the U6847 were smoother to drive and more forgiving. The mini spikes got the best lap time and best lap count so deserve top spot in my mini test. 

  • U6592 Stagger rib (yellow) no foams - baseline count
  • U6775 Cut staggers (silver) no foams - PLUS 1 LAP
  • U6609 Mini pins (yellow) with medium foams - PLUS 3 LAPS
  • U6847 Rib Spikes (yellow) no foams - PLUS 7 LAPS
  • U6550 Mini spikes (green) no foams - PLUS 8 LAPS

Surface was heavily cut up wet muddy grass. 

This does of course mean that after 40 years of chassis design and materials development, the Cougar only beat the Thundershot because of a tyre tread pattern and compound....... On all but the two top tyres here the Cougar was beaten by the Thundershot. Of course this maybe entirely due to 4WD. So to truly test this I need a Schumacher 4WD L1 Evo so I can run identical tyres to the Thundershot and we can rule out the 2WD Vs 4WD element and the tyres. :)

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After finding that the front tyre selection made such a difference to the performance of the Cougar I decided to give the Avante2001 (with Egress shell) another go, this time fitted with the same U6550 slim mini spikes. These are meant to be a 2WD front tyre but I figured that the slim tyre might improve turning compared to the wide full spikes.

The result was truly astonishing, the Avante2001 gained 9 laps compared to running the large wide spiked fronts. Cornering was even better and tighter under power than the Cougar and it could be driven under quite alot of throttle tight around the 8" diameter markers on the hairpins. The suspension is still too firm, the car rides too low (as other than tyres it was running in its tarmac spec including taller gearing). This meant it kept losing traction and bouncing hard on the tree roots and little bumps in the lawn. With a suspension lift and longer softer springs I believe it could get another lap or two easily.

Middle Mudlet also drove the Avante2001/Egress and she got just one lap less then me. We both did two 5 mins races with it.

The Avante2001 is now joint top of our round 7 leader board (with the Cougar) with the Thundershot just 1 lap behind (and that was with the wide full spiked fronts).

 

round7_egress(1).jpg

round7_egress(2).jpg

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It just goes to show that with a little bit of time and investment any one of are chassis's can be made to be better.

So are you going to try using a stabilizing kit? 

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1 hour ago, DayRider said:

It just goes to show that with a little bit of time and investment any one of are chassis's can be made to be better.

So are you going to try using a stabilizing kit? 

Yes DayRider, I will order the rear anti-roll bar kit this week. Not got around to that yet as been busy doing the tyre tests.

Agreed, significant gains to be had in even modest changes to suit a specific track or test circuit. 

I tried changing the Cougar shocks to the most laid down position today and rather bizarrely I got worse performance on the muddy wet grass. I thought they might improve things but I did two 5 min races with both the ribbed spike tyres and the mini spikes and every one was precisely 2 laps down (on the round 7 postal race layout) compared with the standard kit front shock position. So I will revert to kit setup for those.

We also tried my youngest daughters Vanquish today on the same track plan. It has a dirt setup already on its suspension and it showed, far smoother to drive, far superior handling on the bumpy sections of our lawn than either Cougar or Avante2001 and it got just 4 laps less than the Cougar on its first attempt and that was with a lowly sport tuned motor and 7.2v NiMh and using worn mini pin tyres in hard (blue) compound!!!! I reckon with the Dyna Run, 2S LiPo and the same tyres as the Cougar/Avante2001 used for their fastest times the Vanquish could well beat them all. It always was my best buggy on grass. Even youngest Mudlet managed a very respectable lap count with it on just one attempt with no practise!

Of course this is a bit depressing because it is also a plastic bathtub..... If we end up with three plastic bathtubs as our top cars I'm going to cry..... :lol:

round7_vanquish.thumb.jpg.ad287265b36ceed09a83f9aa833d3a89.jpg

398308113_round7_vanquish(2).thumb.jpg.b5e98d48ff58c8b5114b45ac9eefc76c.jpg

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I've just been out and tried the Thundershot on the same tyres as the Avante2001 and Cougar. They were literally taken off the Cougar as they were a brand new set, the Schumacher rear wheels have a little greater outset than when using the DF03 wheels, not sure if this made much difference but the skinny fronts, as found on the other cars, made a significant improvement in cornering under power. Not quite so much as it did with other cars but I gained 2 laps, so the Thundershot is back in top spot but only by a whisker though.

NOTE: To fit Schumacher rear wheels to these old Tamiya you have to fit narrow hexes and use the Schumacher flanged nuts which are thinner than the Tamiya ones. Otherwise the nyloc sits off the end of the thread.

I will try the Vanquish on the same tyres tomorrow.

I'm getting a bit fed up of cleaning the cars though, must have spent at least an hour today just stripping and cleaning muddy grass covered buggies, the sink drain is clogged up with grass and I have mud and grass all over my kitchen :( It was so much nicer running on relatively clean tarmac (pre lockdown).

597996889_round7_thundershot(1).thumb.jpg.4749a6e8f28f799aa9b50949089e4e97.jpg

 

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So what I have learnt about chassis design over the last week?

  • Regardless of how good your chassis is, if you are not on the best tyre for the surface conditions you will get beaten
  • The more race orientated the chassis, the more they seem to be affected by even minor incorrect setups or incorrect tyre choice
  • The choice of tyre widths, patterns and compounds available today is mindboggling compared to the 80's
  • For muddy bumpy rutted grass, higher ground clearance and long travel suspension give superior handling and a more consistent lap
  • On very small test tracks involving lots of steering at lower speeds, a modern 2WD is as capable as a vintage 4WD
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Awesome. Like I said, it's one of the things I love about the hobby making adjustments to get the most out of what you run. I think that we should do a thread on each chassis that we run, what improvements we have made for what surface. I think it would be useful, we all hate wasting money on things that don't fix the issue, plus I think it would be interesting to see and it would help people to know how to make a difference to what they are running. e.g. the next round on the race by post every one could share their set up for the next round. lets see what is or not working?

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7 hours ago, mud4fun said:

I will order the rear anti-roll bar kit this week.

Let me know how you get on with a roll bar on low grip , I was told to only fit one on high grip. Seemingly to let the car roll more, to try and get grip. Then once your getting grip, alter the link washer height to alter the camber once it's rollled.

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@DayRider curiously I just watched a youtube video of Michal Orlowski (Schumacher Team Driver) talking about setup for wet astro. Now I know it is not quite the same as wet muddy grass BUT by some miracle and certainly more by luck than judgement, I had managed to setup the Thundershot with a better wet setup than I have on the Cougar. He recommended high ground clearance, more negative camber on wheels, softer shock oils, softer springs etc. I reckon 90% of his suggestions are already in place on the Thundershot but not the Cougar. The most significant is that the Thundershot is running 5 degree of negative camber on its front tyres whereas the Cougar is kit setup which I think is just 1.5-2 degrees (by the looks of it).

Also he mentioned shortening the wheelbase to generate grip on wet astro. The Thundershot has of course got a shorter wheelbase than the Cougar. Didn't think much of it at the time, just thought SWB meant tighter turning, didn't realise it was better for wet conditions.

So my next task is to get some softer springs for the Cougar (in addition to the anti-roll bar kit), change the camber angles, add shims to the front camber arms,  add a brass electronics tray and a front brass weight.

In fact I need a full range of springs so I can alter them as the weather gets warmer and we go back to tarmac racing after lockdown!

I will report back :)

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