Full Option modified Avante

[LongRat]

Here's my Avante that I started working on for the 2019 Revival.  I'll document the modifications here.

It's a 2011 rerelease, with mods to improve performance and durability but the intention is to keep it as an identifiable Avante.  I don't want to wrap the body around a modern chassis or transform it into an Egress etc.

Mods

• Increased suspension travel so the chassis grounds out before the shocks.  This is using small bore TRF aeration shocks and custom made carbon towers.
• Adjustable caster front end to mount the suspension arms at various angles, using a machined aluminium bulkhead.
• Slipper clutch to allow locked permanent 4WD but with some stress relief on the gears.  The clutch is quite heavily ventilated as it is in a very confined and sealed space in there.

There are plenty of other changes I will likely make, but I would like to get some racing under its belt first to see how these changes perform.

[GTodd]

Please provide pictures and explanation on how you got slipper clutch to work!!!

[Grastens]

Love the paint on this one! I too look forward to reading your findings.

[LongRat]

1 hour ago, GTodd said:

Please provide pictures and explanation on how you got slipper clutch to work!!!

The pressure plates are machined to key directly with the shaft, so they can't move rotationally relative to each other.  Compression of the spring washers is achieved via the screw in the end of the shaft, just like in the standard ball diff option.  I used a modern Schumacher 48DP slipper spur gear and pads, although the gear had to be machined slightly to fit and the central bore enlarged.  The whole thing is an extremely tight fit!

[LongRat]

Installed.

[GTodd]

2 hours ago, LongRat said:

Installed.

DUDE!!!!! That is the answer for EVERY Tamiya 4WD made from the Avante until the Durga. You need to market this!!! How much for two of them? Need them for my Rere Egress and 1989 Avante. 

[LongRat]

I've been talking to a few people, especially Top Force racers who are really interested in this concept. I need to test it properly and work to make it easier to make if I go forward with this. As it stands the clutch is too difficult and time consuming to make in any quantity.

[Jonathon Gillham]

Just now, LongRat said:

I've been talking to a few people, especially Top Force racers who are really interested in this concept. I need to test it properly and work to make it easier to make if I go forward with this. As it stands the clutch is too difficult and time consuming to make in any quantity.

I was going to ask if this could be adapted to a Top Force. I guess it would be possible with the standard spur setup (separate drive gear). But looks like a tight fit. I'm definitely interested in one for the Top Force if it happens 

[ruebiracer]

Just a beautiful design. Played with the same thought and tried to do it with some Tamiya parts, but got stuck due to machining possibilities.

Also the other tweaks on your Avante are so cool. Totally with you in keeping the Avante charactre, and not just doing another Egress.

If the clutch slips, can the front axle rotate differently than the rear axle? Or did you design with permanent 4WD and just let the spur gear slip?

My thought was always to let both axle slip to each other, to be able to take out tweakings in the drive train. (just as is intended by the centre diff) 

Hats down on your very professional looking solution,

will follow this thread for sure!

 

Kind regards,

Matthias

[ruebiracer]

Sorry, just read that you keyed the shaft. Didn´t read properly enough. So you use permanent 4WD already...

I´m not in the buggy racing business since the mid 90`s, but probably it´s the std. 4WD Setup nowadays, if a slipper is used?

If you oneday show us the tear down of your invention, that would be cool. What I found hard on the Avante ball diff design is that the bevel gear position on the axle is influenced by how much the pressure discs are screwed down. 

[matisse]

8 hours ago, GTodd said:

DUDE!!!!! That is the answer for EVERY Tamiya 4WD made from the Avante until the Durga. You need to market this!!! How much for two of them? Need them for my Rere Egress and 1989 Avante. 

Indeed, if this could be made to work on the TF.... Game Changer

[LongRat]

20 minutes ago, ruebiracer said:

Sorry, just read that you keyed the shaft. Didn´t read properly enough. So you use permanent 4WD already...

I´m not in the buggy racing business since the mid 90`s, but probably it´s the std. 4WD Setup nowadays, if a slipper is used?

If you oneday show us the tear down of your invention, that would be cool. What I found hard on the Avante ball diff design is that the bevel gear position on the axle is influenced by how much the pressure discs are screwed down. 

Thanks Matthias.

In practice I've found that the spring washers move such a small amount when the clutch pressure is adjusted it doesn't have a significant effect on the gear mesh.

On the subject of decoupling the front and rear axles, to achieve this you could modify the standard centre diff with friction pegs instead of balls. The issue when racing is that this would slip the front under braking and so the rear under acceleration and I think handling might be inconsistent. Basically most modern 4wd transmissions are locked 4wd and slip the whole drivetrain together, like my design. Take a look at the machined components here:

[GTodd]

Oooops 😄

[GTodd]

3 hours ago, LongRat said:

Thanks Matthias.

In practice I've found that the spring washers move such a small amount when the clutch pressure is adjusted it doesn't have a significant effect on the gear mesh.

On the subject of decoupling the front and rear axles, to achieve this you could modify the standard centre diff with friction pegs instead of balls. The issue when racing is that this would slip the front under braking and so the rear under acceleration and I think handling might be inconsistent. Basically most modern 4wd transmissions are locked 4wd and slip the whole drivetrain together, like my design. Take a look at the machined components here:

WORK OF ART!

[ruebiracer]

Thank you so much for your explanations and pics! It´s truly a work of art with the ventilated design. Also to swap the axial bearing to the front side is clever. One problem I had with not keyed design was unscrewing under some circumstances. In fact only some track experience can show the advantages of centre diff function or permanent 4WD. Would love to do those tests for myself on a proper offroad track.

Keen on your track tests!

Great ideas in this project, and love the Vintage-Tamiya paint job. I still have a wing with the same decal from back in the days...

 

[Howards]

That slipper looks the business. 

 

If they made it into production I'd be on the list for one.

[ruebiracer]

Any News on your fantastic project Longrat?

You just sparked my ambitions, and I was working again on my slipper solution based on the original diff.

I fiddled a bit and shimmed, I was able to clear my 82T DF03 spur gear the lower gears down in the gearbox. So I ordered a 25T pinion and got my first 1,5 batteries on it, using my Avante 2001 as test rig. So far I could only run in the garden on higher grass on 13,5t brushless. But some jumps and hills it cleared perfect. Although I ran it with nearly no slip for the beginning, to see if it can hold the torque or would maybe loosen up. 

Next step will be running it on a looser level. Hope the weather gets warmer and dry again...

Kind regards,

Matthias

 

[Avante2001R]

On 3/28/2020 at 11:17 PM, LongRat said:

The pressure plates are machined to key directly with the shaft, so they can't move rotationally relative to each other.  Compression of the spring washers is achieved via the screw in the end of the shaft, just like in the standard ball diff option.  I used a modern Schumacher 48DP slipper spur gear and pads, although the gear had to be machined slightly to fit and the central bore enlarged.  The whole thing is an extremely tight fit!

Looks great are you planning to release a kit?

[ruebiracer]

12 minutes ago, Avante2001R said:

Looks great are you planning to release a kit?

He did an Incredible good job on the design, the air channels are also the notches, where the bevel gear snugs in and is transferring the torque to the plate. The step on the Alu part is to center the gear. He just thought of everything.

But he wrote already, that it´s to special and time consuming to make in any quantity. So no hope for a kit at the moment. But there would nowadays be a market in the Vintage racing scene and for technic lovers for sure..

[LongRat]

On 5/3/2020 at 6:05 PM, ruebiracer said:

He did an Incredible good job on the design, the air channels are also the notches, where the bevel gear snugs in and is transferring the torque to the plate. The step on the Alu part is to center the gear. He just thought of everything.

But he wrote already, that it´s to special and time consuming to make in any quantity. So no hope for a kit at the moment. But there would nowadays be a market in the Vintage racing scene and for technic lovers for sure..

Thanks for noticing those small but essential features  makes the time to design it all the more worthwhile!

I'm really happy to see your slipper solution, please let us know how it performs long term especially slipping a bit.  If it works well it would be a much easier solution to the problem for a lot of people.  I haven't had a chance to run mine at all, no tracks open and no time or places within range of me to test it properly.  That time will come.

[Ann3x]

I also had a long attempt to make a slipper spur (for a Topforce actually). In the end found this as a simpler option: https://www.modelsport.co.uk/carisma-m40dt-slipper-pinion-set/rc-car-products/381157

As you say its VERY snug fit for any useful spur based slipper design. It's probably possible but will have some inherent issues i think due to the spring throw. Ive come to believe a slipper pinion is a more universal option for older buggies.

[LongRat]

Thought I would update the thread with some more info on the other mods on this car.  I have run it at every IconicRC Revival since 2019, it's now quite dependable and I have won several B finals over those years, I don't think it's made the A yet but I'm still pretty happy given the level of competition now at these events.

One durability upgrade is the aluminium top link mount at the front.  Stops the need for ball studs being screwed down into the gearbox and removes the slight binding at max travel it had before.
I've also added a photo of my front kick-up mount system.  Raising the height of the front arm mounting increases kick up and caster.  This method would actually only work properly with an Avante, taking advantage of its 'balls everywhere' suspension design.  Anyway the mid setting I think works out at about 25 degrees, I have tried it with more but it doesn't feel right, and less returns the geometry to standard - a much twitchier feel especially with such a short wheelbase car.  Way slower over the lap.

[Saito2]

Excellent idea and one I have contemplated considering the Avante's rather unique "arm" design. Can you elaborate on how it feels to drive with the increased kick-up? One would assume it would be a significant improvement over the standard Avante's "nervous" character.

[toyolien]

6 hours ago, LongRat said:

Thought I would update the thread with some more info on the other mods on this car.  I have run it at every IconicRC Revival since 2019, it's now quite dependable and I have won several B finals over those years, I don't think it's made the A yet but I'm still pretty happy given the level of competition now at these events.

One durability upgrade is the aluminium top link mount at the front.  Stops the need for ball studs being screwed down into the gearbox and removes the slight binding at max travel it had before.
I've also added a photo of my front kick-up mount system.  Raising the height of the front arm mounting increases kick up and caster.  This method would actually only work properly with an Avante, taking advantage of its 'balls everywhere' suspension design.  Anyway the mid setting I think works out at about 25 degrees, I have tried it with more but it doesn't feel right, and less returns the geometry to standard - a much twitchier feel especially with such a short wheelbase car.  Way slower over the lap.

Any plans to produce any of these parts? I'd like to try racing my Avante also.

[LongRat]

I am considering producing a racing suspension set, including the geometry and strength upgrades here. I'll post here if that does become a reality.