Egress<Terra Scorcher?

[Saito2 6686]

After doing some research for the Egree/Avante analysis thread, I sat the Egress down next the Terra Scorcher and began to compare them. Is it possible the Terra Scorcher might be the better off road buggy over the exotic Egress? Drivetrain-wise the Egress does get the nod with multiple options front and rear plus center while the TS has no center diff and relies on only gear diffs F/R. Where I began to question things was in the suspension/steering. The Egress grants you pretty much one way to mount the dampers. The TS, on the other hand, gives you 4 ways front and rear, out of the box. Camber link mounting is basically fixed on both buggies though the Egress does have an extra set of holes in its uprights up front. The Egress has basically no front kick-up and also little caster. This is probably why its considered a nervous, darty buggy with poor cornering feel. The TS does have some kick-up and consequently caster as well. The Egress has much more scrub radius than the TS too. 

So, I'm left wondering, despite all the "tech" packed into the Egress, is the more straight-forward, more pedestrian Terra Scorcher actually the better performer of the two?

[Fruitfly01 596]

The Thundershot range of buggies are based on quite a capable chassis.  Unfortunately released at a time when racers were droppping their Hotshots and Bigwigs in favour of belt driven, fibre glass buggies from other companies.  If the racing charts of the day are anything to go by Hotshots and Bigwigs were often making A finals and taking first place.  If the Thundershot buggies were released a year sooner, I think they would have been a force to be reckoned with out on track.

People often cite the Manta Ray chassis as development of the changes made to the Egress in its racing life.  That maybe true,  But if you look at the changes made to the Egress, specifically Jamie Booth's car, you can see how many of the unique features of that chassis were replaced with many standard components - a traditional suspension set up with normal wishbones and damper mounting points, as well as a little kick up at the front to help it ride the bumps a bit better.  The steering knuckle was also replaced with a  Hotshot item, helping to reduce scrub radius and improve steering and ease pressure on the front drive train through its suspension travel.

All of these changes made the Egress much more like the Thundershot, which then lead to the development of the Manta Ray.  if you look at a Manta Ray and a Thundershot side by side, they are practically identical at first glance. - Transverse motors, shaft driven with bevel gears either end and no slipper clutch, twin bellcrank steering,  geared differentials front and rear of the same design internally, traditional double wishbone suspension all round, as well as yellow CVA dampers.  

If anything, Tamiya scrapped the Egress design altogether, went back to the Thundershot, evolving the chassis with many subtle changes learned in the field, a produced the new plastic fantastic, which became the basis of a new all out racing machine.

With a few tweaks, the Terra Scorcher is, or would have been quite the performer on the track, as is evident by what came before it, and what it ultimately became in the Top Force.

 

[Saito2 6686]

That's about how I felt about Tamiya's 4wd buggy development. You can draw a line form the Hot Shot series to the Thundershot series to the Manta Ray/DF01 series. The Avante/Egress series was an outlier. Its almost conceivable that the evolution of the other buggies would/could have happened if the Avante cars didn't get produced at all. The Avante to Egress was a plunge forward down that line of development only to readjust course with the Booth Egress by actually bringing it more in line with the other Tamiya buggies. Its common to say the Top Force bested the Egress and that might even be true of the Manta Ray as well. When I looked back at the Thundershot series which was pretty much ongoing simultaneously as the Avante series, I began to consider even it might have an edge. It was also clever on Tamiya's part to make one chassis series, the DF01, to cover both the high and low end of 4wd (not to mention what it spawned in touring car, etc.).

[moffman 5752]

I think you have good valid points! You ask any racing driver F1, rallying, touring car etc they all say you have a better racing experience if the car your in is simple no power steering no electronic gizmos to keep you on the road! A few years ago I was fortunate enough to have a rally day experience and the rally cars they used were a 30 year old Ford escort and a 20 year old Peugeot 206 simply because they were 5 speed manual with nothing electronic to stop you feeling the surfaces you are rallying on! although the 206 had power steering so I think the same goes with these two RC buggies bells and whistles (so to speak) don't always get results! My original thunder shot back in the days was good but my cousins mardave meateor in the school hall Friday night racing used to leave my thunder shot for dust!

[Howards 456]

Given that it took Tamiya until the TCC to produce a drivetrain that was capable of handing the modified motors of the time, all their previous efforts, DF01 included, were somewhere between Garbage and OK on the 'viable club racer' scale. Given what it was up against at the time, it's difficult to claim the TopForce was an all out racing machine. Even in Evo config the lack of a resilient drivetrain meant it would never really compete. The team drivers cobbled a 4wd drive racer from a Dynastorm with it's gearbox flipped and modified to take an additional belt pulley. 

So at least the Egress was actually raced, seriously at the top level, even if in a modified form.

14 hours ago, Saito2 said:

The Avante to Egress was a plunge forward down that line of development

An evolutionary dead end. That said, I do wonder if there was something specific to Japanese RC racing that made the design decisions they made at the time look a bit more sensible.

It's interesting to compare an Egress to a DB01, the later has very little kick up but not inconsiderable caster. But the main difference seems to be wheelbase and length of wishbones and steering geo. Motor and battery layout are very similar at a glance.

[Saito2 6686]

7 hours ago, Howards said:

DF01 included, were somewhere between Garbage and OK on the 'viable club racer' scale. Given what it was up against at the time, it's difficult to claim the TopForce was an all out racing machine. Even in Evo config the lack of a resilient drivetrain meant it would never really compete.

I will give the Avante/Egress credit for having a fairly robust drivetrain. Being a top end buggy for Tamiya from the get-go meant it got some glass reinforced plastics for the gear cases and such. The Top Force/Evo, being built on the jack-of-all-trades DF01 platform, had to deal with standard ABS or PC plastics. I agree, if you look at the TF/Evo's competition, they were all belt driven and by that time slippers were in vogue. In some ways, from a durability standpoint at least, the Terra Scorcher drivetrain might have been tougher than the DF01, if not as flexible.

7 hours ago, Howards said:

That said, I do wonder if there was something specific to Japanese RC racing that made the design decisions they made at the time look a bit more sensible.

It's interesting to compare an Egress to a DB01, the later has very little kick up but not inconsiderable caster.

I wonder this too. The smoother the track, the better the Egress's chances. I guess you don't see kick-up in on-road cars. Its my understanding that 4wd buggies have less kick-up than 2wd ones ideally, but for the Egress to have no kick-up nor caster made for a nervous buggy.

[Rb4276 803]

42 minutes ago, Saito2 said:

 

I wonder this too. The smoother the track, the better the Egress's chances. I guess you don't see kick-up in on-road cars. Its my understanding that 4wd buggies have less kick-up than 2wd ones ideally, but for the Egress to have no kick-up nor caster made for a nervous buggy.

This makes sense, I take my egress often to a large baseball field with an all dirt infield and it drives smooth as butter with proline blockades front and back. 

[MadInventor 3884]

My 2 Cents:

1. Don't forget you can fit the Tamiya 53200 one way roller in the terra scorcher  for a bit of extra tuning potential (I've got one ready to go in mine)

2. Thundershot series transmission is pretty bombproof. A few years ago I was doing speed runs with mine running a 4000Kv hobbywing brushless system along with a 9.6V battery, so I think back in the 80s it would have had no issues with running vintage modified motors on a 7.2v NiCad.

3. I did prefer driving the Vanquish I had back in the day to the thundershot that preceded it, but I was just bombing them round the garden, not going racing with them.

4. The kyosho optima mid is a better design than the Egress or the thundershot. It's a great combination of gear drive to the rear axle and belt drive to the front axle, and a simple but tuneable suspension geometry.

 

[ruebiracer 1046]

9 hours ago, Saito2 said:

I will give the Avante/Egress credit for having a fairly robust drivetrain. Being a top end buggy for Tamiya from the get-go meant it got some glass reinforced plastics for the gear cases and such. The Top Force/Evo, being built on the jack-of-all-trades DF01 platform, had to deal with standard ABS or PC plastics. I agree, if you look at the TF/Evo's competition, they were all belt driven and by that time slippers were in vogue. In some ways, from a durability standpoint at least, the Terra Scorcher drivetrain might have been tougher than the DF01, if not as flexible.

I wonder this too. The smoother the track, the better the Egress's chances. I guess you don't see kick-up in on-road cars. Its my understanding that 4wd buggies have less kick-up than 2wd ones ideally, but for the Egress to have no kick-up nor caster made for a nervous buggy.

And who the badword began to post first, it has no castor? When I look at the rerelease aluminum uprights, the upper knuckle hole is more backwards than the lower one.

This is castor... Maybe I should get my Vanquish on my touring car setup station to measure the value, but when steering you see the tire tilting, so there is some castor built into the axle. Not by kickup, that´s true.

[Frog Jumper 3661]

All you people need to stop stroking the Terra Scorcher.  Any more fluff and I’m going to have to buy one!  Grrr!

[Howards 456]

2 hours ago, ruebiracer said:

And who the badword began to post first, it has no castor? When I look at the rerelease aluminum uprights, the upper knuckle hole is more backwards than the lower one.

Compared to contemporary buggies and some buggies of the time it has so little caster that it's easier just to write no caster

[kyosho1 86]

On 7/29/2020 at 5:16 AM, Saito2 said:

That's about how I felt about Tamiya's 4wd buggy development. You can draw a line form the Hot Shot series to the Thundershot series to the Manta Ray/DF01 series. The Avante/Egress series was an outlier. Its almost conceivable that the evolution of the other buggies would/could have happened if the Avante cars didn't get produced at all. 

For the 4WD buggies, I think the Porsche 959 might have started the longitudinal motor placement design. That placement allows the CG to be more centered and this probably spurred the development of the Avante chassis. 
That in turn evolved into TT01/02 buggy,  DB01, DF02 & TRF502. And not forgetting their competitors jumping into the same bandwagon eg Associated.

Correct me if I am wrong, but a centered CG for a 4WD buggy allows better cornering and mid-air roll, pitch and yaw control.

As for the Avante”s suspension design, it’s probably adapted from the Rear suspension of the Racing Buggy series where the drive shaft pivot along the same line as the lower arm suspension, probably to provide better ground clearance for off road.
 

 

 

[Saito2 6686]

14 hours ago, ruebiracer said:

And who the badword began to post first, it has no castor?

This is my fault. I wasn't specific enough when I wrote this:

23 hours ago, Saito2 said:

for the Egress to have no kick-up nor caster

In the first post of the thread I more specific and wrote this:

On 7/28/2020 at 3:21 PM, Saito2 said:

The Egress has basically no front kick-up and also little caster.

 

I think honestly, if I'm reading the technical drawing found on the Tamiya replacement parts blister card correctly, there's about 10 degrees in those old uprights. But, typically, don't off road buggies, even 4wd ones, usually run some kick-up? Kick-up affects castor.

"Tuning with Kickup
0deg of Kickup will give the car a more aggressive steering feeling, but will not handle bumps well."

That's a quote I grabbed from an article about suspension tuning. I may be wrong about all the deductions about the Egress. I was going off of research from knowledgeable forum members, an interview with Jamie Booth and people's complaints about how the car reacted. I honestly may be missing something here and welcome any corrections.

11 hours ago, kyosho1 said:

As for the Avante”s suspension design, it’s probably adapted from the Rear suspension of the Racing Buggy series where the drive shaft pivot along the same line as the lower arm suspension, probably to provide better ground clearance for off road.
 

Excellent observation. I never made that connection. That might be exactly what the designer was thinking.

 

Edit: I'd like to apologize for missing the actual amount of caster the Egress does have in its uprights. Thank you @ruebiracer for correcting me. Future readers, please dismiss most of my inarticulate ramblings as I feel I probably didn't have a firm enough grasp on the material to be posting about it. Sorry if I misled anyone. 

 

 

[Howards 456]

They did seem to think that ground clearance, and masses of it, was important. God knows what they thought they would be racing on.

RE caster - depending on the attitude of the chassis the amount of caster is dynamic - i.e. landing nose down will result in a positive caster value. I suspect the DB01, landing nose down will have to go quite steep before it has a positive caster angle. Egress, not so much - pop the rear wheel up a fraction and boom, zero caster.

[MadInventor 3884]

5 hours ago, Frog Jumper said:

All you people need to stop stroking the Terra Scorcher.  Any more fluff and I’m going to have to buy one!  Grrr!

Good luck trying to find one.........

2 hours ago, kyosho1 said:

For the 4WD buggies, I think the Porsche 959 might have started the longitudinal motor placement design. That placement allows the CG to be more centered and this probably spurred the development of the Avante chassis. 
That in turn evolved into TT01/02 buggy,  DB01, DF02 & TRF502. And not forgetting their competitors jumping into the same bandwagon eg Associated.

Correct me if I am wrong, but a centered CG for a 4WD buggy allows better cornering and mid-air roll, pitch and yaw control.

As for the Avante”s suspension design, it’s probably adapted from the Rear suspension of the Racing Buggy series where the drive shaft pivot along the same line as the lower arm suspension, probably to provide better ground clearance for off road.
 

 

 

The problem with the longitudinal motor placement and propshaft in the centre of the car is that is makes torque twist on the chassis awful when you go up in power. I had huge problems with a TT-01 trying to run a 4000KV motor in it (It was on 3S...). when you applied the power the car pulled hard to one side. TT-01 / DF-02 style transmission have evolved into that because you are making a 4wd car with the absolute minimum number of transmission components, it's a cost saving exercise more than an optimal layout. If you look at transverse motor mounting in old cars like the CAT and the optima mid, the motor is mounted centrally (left to right) in the car for excellent balance, and the transmissions work in a way that do not put torque twist into the chassis under power (Belt drive). To look at extreme examples, the clod buster has no torque twist, and my TXT-1 can't keep 2 front wheels on the ground. With regard to mid air roll pitch and yaw, you can't steer in mid air (Yes, you can affect pitch somewhat with throttle). Centrally mounted motors IMO are just a gimmick to sell the next generation of cars, the actual benefit they give seems to me very minimal, as you could quite easily have a conventional transverse motor layout with the motor just in front of the rear axle, and then adjust the CG fwd and aft in the car to suit with the battery location.

[ruebiracer 1046]

10 hours ago, Saito2 said:

Edit: I'd like to apologize for missing the actual amount of caster the Egress does have in its uprights. Thank you @ruebiracer for correcting me. Future readers, please dismiss most of my inarticulate ramblings as I feel I probably didn't have a firm enough grasp on the material to be posting about it. Sorry if I misled anyone. 

Hey Saito, no need to apologize! I didn´t want to be offensive, just wanted to give a hint between the differences between kickup and castor on the Avante series.

You started a superinteresting thread and it´s so informative to read everyones inputs here! That´s why we are around here!

For me there is no doubt, that Tamiya designed the Avante with all it´s specs exactly as ithey wanted it to be, with no kickup and little castor for very aggressive steering, just like a "Formula 1 car for offroad". Time told, that it was too much for the tracks of the time. For me, this doesn´t hurt the icon "Avante" and it´s derivates from today´s point of view. Designwise, as a whole compilation of body , chassis and the complete package, it´s the most beautiful buggy ever, together with Vanquish, 2001 and Egress. The competitors looked always a bit edgy, "compromisy", not modelled as deeply as this Tamiyas. That´s why nowadays it sells so good, as people are realising it´s historic value.

I like Black hole suns Avante story a lot, he covers everything really well, in my eyes.

https://www.blackholesun.fr/en/39-en/tamiya/201-tamiya-off-road-chassis?start=12

Of course, it´s my personal opinion and I´m Tamiya fan since childhood. My goal was always to bring Tamiya back in front on the Race tracks of the world.

Seems I´m always more on the side of the underdogs...  Each to their own preferences,

Have a nice weekend everyone,

Matthias

[Avante2001R 305]

The driveline of the Egress was much better IMO for its time. Just the flaws were around the unconventional suspension design. I think the Jamie Booth TRF design addresses that somewhat - but if a conversion kit could be developed to use more modern arm/hub carrier and driveshaft setup it would be an incredible buggy. 

[Avante2001R 305]

One of the guys from Australia made this really nice setup by hand car seems to handle well from the videos he posted. This idea could be further developed refined and made as a kit- are people prepared to pay? I would definitely look at offering something but there needs to be a demand - at least 30-40 kits. 

[kyosho1 86]

10 hours ago, ruebiracer said:

..... that Tamiya designed the Avante with all it´s specs exactly as ithey wanted it to be, with no kickup and little castor for very aggressive steering, just like a "Formula 1 car for offroad".

I agree with your observation.
I think maneuverability was in the cards - low +ve caster angle, short wheelbase, front big tyres and steep angled coil-over front shocks.  

The servos during that period had good torque/strong so Tamiya probably thought straight line stability will not be compromised with low +ve caster angle but with so much play in the steering system, the front tyres were flopping all over on a bumpy track just like a 🐠 out of the water, making a nervous handling buggy. I think if the steering linkages were tight and accurate coupled with strong suspension parts  (previously aluminum tapered rods were used which bent easily & the brittle grey upright bracket thingy & the brittle grey rocker arm for frontal collision), Tamiya could have pulled off a winner out of the box as a reliable competitive buggy)
I have seen an Avante beat a Yokomo dogfighter YZ10  by 1 car length in an A mains Final in 1989 (Singapore) - the Avante was able to take a few corners tightly (like on rails) till it crossed the finishing line first. 

However if the Avante is driven on the tar road on sponge tyres (like the yesteryear”s Tamiya F1 tyres), it runs and handles silky smooth.

[kyosho1 86]

8 hours ago, Avante2001R said:

One of the guys from Australia made this really nice setup by hand car seems to handle well from the videos he posted. This idea could be further developed refined and made as a kit- are people prepared to pay? I would definitely look at offering something but there needs to be a demand - at least 30-40 kits. 

The development of the replica of Jamie Booth TRF Egress - a must read 😄

 

[Howards 456]

17 hours ago, MadInventor said:

Centrally mounted motors IMO are just a gimmick to sell the next generation of cars, the actual benefit they give seems to me very minimal, as you could quite easily have a conventional transverse motor layout with the motor just in front of the rear axle, and then adjust the CG fwd and aft in the car to suit with the battery location.

Broadly fine when everyone was on NiMH but it’s hard to get some weight on the front wheels when lipo batteries weigh so little. I believe that’s where the mid motor comes in handy.

obvs Tamiya wasn’t thinking about that around 1989

Also I think the high levels of grip on modern tracks and the large and long jumps have driven designers to put more emphasis on weight front for agility as a counter to the long wheelbases and suspension set ups that work hard to keep the car stable that we see now. 

[Avante2001R 305]

1 hour ago, kyosho1 said:

The development of the replica of Jamie Booth TRF Egress - a must read 😄

 

I know about the JB egress and I also had the full option kit. There are still improvements that can be made to that. Remember the replica was a straight up replica also carrying over any flaws which it did have from 89. Credit to the guy for making the kit and it was really well machined and made. I’m just saying it can be further improved. 

[graemevw 823]

I've driven my egress and my terra scorcher back to back, on track, many times. Overall the terra scorcher is easier to drive quick. The terra scorcher is more intuitive, along with my procat, rc10, super astute etc. They all just do what I ask.

Whenever I switch back to the egress I have to 're train my brain and think differently. 

My vanquish had a load of rere egress bits, shocks, uprights etc, and a load of chassis stiffening and it drove better than the egress, although still required more thought than my other cars. Only real difference in my vanquish set up to my egress set up is the vanquish was maybe 10mm lower (I lowered it)

I think the egress has more potential without major mods, I've just not got round to sorting it. It also seems super fussy about tyres. I think it would benefit from less front grip so I'll swap the front tyres out from the various mini pins types I have to maybe some blocks or stagger ribs and see if that balances it a bit more.

I do plan to try and get some front castor in it too somehow, I've heard front arms can be twisted. Pretty sure Jamie booth told me to heat and twist them.

[Avante2001R 305]

I always found the Egress very well balanced. I’m going to do a little project and fit modern suspension setup to one of mine. I’m no fan of the Egress ackerman angles, scrub radius and caster. Would also engineer some anti squat to the rear arm geometry. 

[Saito2 6686]

On 7/30/2020 at 3:25 AM, kyosho1 said:

As for the Avante”s suspension design, it’s probably adapted from the Rear suspension of the Racing Buggy series where the drive shaft pivot along the same line as the lower arm suspension, probably to provide better ground clearance for off road.

 

On 7/30/2020 at 5:11 AM, Howards said:

They did seem to think that ground clearance, and masses of it, was important. God knows what they thought they would be racing on.

After re-watching the Avante promo, the voice over guy makes a the statement "The arms were designed not to extend down from the chassis bottom, allowing good ground clearance." at around the 1:50 mark. This is further confirmation @kyosho1 and @Howards are correct and gives good insight into why the "unique" way the Avante's front end was designed as such.