SHY69

Tamiya B.A.R. Honda Hotshot Evo IV

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Hi guys! Just thought I'd share some Hotshot love with you. My car is a hardcore runner and my weapon of choice in the Nordic Vintage Challenge series, in the "4WD Classic" class.

Here you can read up on it's evolution so far:

Evo I: http://www.tamiyaclub.com/showroom_model.asp?cid=82946&sid=22039
Evo1_pic1.jpg
(I remember you found this wing too large Max, and I agree :rolleyes: )

Evo II: http://www.tamiyaclub.com/showroom_model.asp?cid=106011&sid=22039
HotShotEvoII9.jpg

Evo III: http://www.tamiyaclub.com/showroom_model.asp?cid=125472&sid=22039
pic1.jpg

And some more info in a build tread (in norwegian):
http://rsb.se/arena/showthread.php?90521-SHYs-Re-re-B-A-R-Honda-Hotshot-gt-NVC-warrior

This is how it went in the last race - NVC#3:

TQ and 3rd place. I won the first final by 2 laps, but ran into DNF in the last two as I simply smoked the 19T brushless motors...

Great fun anyways, and we never rest - so this is the plan for Evo IV:

-Gear down from 13T to 12T (using Kontemax's genious mod on his Boomerang)
-Make inspection hole in order to check gear mesh (open close with round sticker)
-Free up the drivetrain by rounding all gears
-Free up the drivetrain by using metal shielded bearing only + clean out grease and use teflon oil (the ones in the gearbox will be left with grease)
-Thorp ball differentials front and rear
-One TRF front shock was leaking a lot > fix
-Double up rear shock mount
-Move the rear wing back, mount on rear shock tower
-Better front sway bar holders (CRP material, the alu from Radshape is way too soft)
-Try without swaybars (should be less prone to traction roll with Mini Pins / less grip)
-Cooling ribs and fan on motor (should reduce it by 30 degrees)
-DF03 universal shafts in the rear
-Boomerang rear arms & upright in order to get toe-in (0 deg is std on Hotshot)
front vs bak?
-Maybe use links in the rear for upper arms = can adjust camber
-Try and get front upper arms from Parma for camber adjustment and caster angle adjustment
-New wheels & tires (new regulations - Mini Pin now)
-Get steel hex screws in correct lenghts

-Wider a bit more with wider hex in the front?

Thx for looking, comments and suggestions are always welcome! :D

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-Gear down from 13T to 12T (using Kontemax's genious mod on his Boomerang)

Great!

-Make inspection hole in order to check gear mesh (open close with round sticker)

Not sure if you will have a good result, I did it and it wasn't. Check it on an old ruined gearbox before.

-Free up the drivetrain by rounding all gears

Interested to see the result. I wouldn't file the Thorp ball diffs eheheh!

-Free up the drivetrain by using metal shielded bearing only + clean out grease and use teflon oil

Good idea but wants frequent refurbishments

-Thorp ball differentials front and rear

Lucky man!

-One TRF front shock was leaking a lot > fix

-Double up rear shock mount

-Move the rear wing back, mount on rear shock tower

-Better front sway bar holders (CRP material, the alu from Radshape is way too soft)

Use carbon fiber plate.

-Try without swaybars (should be less prone to traction roll with Mini Pins / less grip)

Not sure you have the dual front shock set up.

-Cooling ribs and fan on motor (should reduce it by 30 degrees)

-DF03 universal shafts in the rear

Will not mount on the Thorp drive cups, sorry.

-Boomerang rear arms & upright in order to get toe-in (0 deg is std on Hotshot)

front vs bak?

-Maybe use links in the rear for upper arms = can adjust camber

-Try and get front upper arms from Parma for camber adjustment and caster angle adjustment

-New wheels & tires (new regulations - Mini Pin now)

-Get steel hex screws in correct lenghts

-Wider a bit more with wider hex in the front?

Thx for looking, comments and suggestions are always welcome! :D

Max

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Thx Max! Why don't the unis fit in the Thorp outdrives?

Does that mean that the re-re dogbones won't either?

Gotta say it's very annoying that forums have such a low limit on attachments! Plus you can't link from TC showrooms :(

OK then, back to Photobucket it is :rolleyes:

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The original drive cups are bigger than the rerelease ones.

Thorp ball diffs are vintage so they are compatibles with original half shafts.

You should have mine Universal Joints that are vintage.

Origibal drive cups are 11 mm esternal and 7 mm internal. The rerelease ones are 10 mm external and 6 mm internal.

If you use modern cvd on vintage drive cups probably they move too much inside the drive shafts and the pins are to short.

Max

Thx Max! Why don't the unis fit in the Thorp outdrives?

Does that mean that the re-re dogbones won't either?

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The original drive cups are bigger than the rerelease ones.

Thorp ball diffs are vintage so they are compatibles with original half shafts.

You should have mine Universal Joints that are vintage.

Origibal drive cups are 11 mm esternal and 7 mm internal. The rerelease ones are 10 mm external and 6 mm internal.

If you use modern cvd on vintage drive cups probably they move too much inside the drive shafts and the pins are to short.

Max

OK, I'll see if I can find a solution then <_<

Are vintage unis possible to find?

Pretty quiet on this forum huh?

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Yes, sometimes the people don't like some thread, like my Boomerang refurbishment one.

Pratically it was a blog ;)

Anyway there's a solution but it is not easy and cheap.

You can go in some mechanical workshop with your Thorp drive cups and they will make a copy of them with the new drive cups layout. You need to replace only the drive cups not the entire ball diff.

Another solution is to built the half shaft, not the entire half shaft, just the shaft part with a bigger ball head but I believe it's more easy make the drive cups.

Ah, I forgot the most expensive and difficult solution: find the vintage universal joints... :D

Max

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I see the original Hotshot driveshafts are easy to find but stupid expensive...

any other low priced std dogbones that would fit?

Worst case I'll use some old ones I have and just replace the pins.

Unis are no must have, especially in the rear.

/blog updated/ :P

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OK, so this is the "plan" so far for the driveshafts:

1) Replace the 2mm pins with ones that are long enough
2) "Coat" the ball part of the dogbone with some material to make it fit into the outdrive

Now then there's the question as to material:
-shrinkwrap (will wear quickly but will easily stay in place)
-3M DP490 (I love this stuff!)
-Araldite (often becomes too soft)

It might even work so simply shim onto the pins so that the ball cannot move sideways...

Any suggestions?

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Can't really add anything to this, but I am enjoying all the mods.

Please keep it coming :)

Rich

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Can't really add anything to this, but I am enjoying all the mods.

Please keep it coming :)

Rich

Thx for that! :D

Parts are slowly arriving in my mailbox...

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Keep in mind that the pins are 2 mm of diameter but the problem is the part of the pin that is inside the ball head of the shaft. In fact it is bigger than 2 mm because the pin mounts for interference. Another problem is to find an enough hard material to replace the pin.

Max

OK, so this is the "plan" so far for the driveshafts:

1) Replace the 2mm pins with ones that are long enough
2) "Coat" the ball part of the dogbone with some material to make it fit into the outdrive

Now then there's the question as to material:
-shrinkwrap (will wear quickly but will easily stay in place)
-3M DP490 (I love this stuff!)
-Araldite (often becomes too soft)

It might even work so simply shim onto the pins so that the ball cannot move sideways...

Any suggestions?

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I just found this thread and thought I'd add some ideas...

Instead of using a ball diff in the front have you thought about using 1 way roller drive shafts ? I seem to remember the CAT xls using a solid spool at the front, with 1 way bearings fitted inside part of the front drive shafts to give free wheeling hubs. The CAT items can't be made to fit, but you might be able to find a modern equivalent that would fit either vintage or re-re drive cups.

Back in the 80's I fitted a 1 way roller shaft in my centre drive shaft on my hotshot (I butchered a set of PB ace 1 way rollers to do this :ph34r: ). Can't remember what a performance difference it made, just chucking the idea out there that it is possible to do. PB ace universals also fit in vintage hotshot drive cups, but good luck finding them ...........................

I've vented by mech deck cover to let more air to the ESC:

img33435_09122012185921_1.jpg

I've replaced the plastic part that goes on the screw that holds the motor through the set plates with brass or aluminium items, so that the screw can be tightened without distorting the plastic.

If you're going to go with hotshot II style rear suspension I'd look for a HS II underguard for the rear as well.

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Pretty quiet on this forum huh?

Only because a lot of us lack the technical expertise to give you advice for such a specialized situation - or maybe just me ;)

Either way, I remember this Hotshot well due to that distinctive livery - it looks great! That would have been about the extent of my "technical" comments!

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You chose the complicated solution to a simple problem ;) . I made this plate with a lexan sheet, easy to cut and easy to drill.

Max

I've vented by mech deck cover to let more air to the ESC:

img33435_09122012185921_1.jpg

I've replaced the plastic part that goes on the screw that holds the motor through the set plates with brass or aluminium items, so that the screw can be tightened without distorting the plastic.

If you're going to go with hotshot II style rear suspension I'd look for a HS II underguard for the rear as well.

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You chose the complicated solution to a simple problem ;) . I made this plate with a lexan sheet, easy to cut and easy to drill.

Max

Simple for me with a milling machine though. Faster than cutting from lexan ;)

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You lucky man!

Can you do gears 0.8 module?

Max

Simple for me with a milling machine though.

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You lucky man!

Can you do gears 0.8 module?

Max

I buy mine from HPC Gears in the UK. They do steel gears at a price where it's better for me to do overtime and pay for them than make them myself.

www.hpcgears.com

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Now we're talking - thx for all the comments guys! :D

Madinventor, does this ring a bell? ;)

DivPicsHotShotEvoII.jpg

pic4.jpg
A small homage to you there! You made both my front brace and alu washers for the motor mount, been working great!

When I needed cooling I simply removed the whole inspection hatch. But that crappy stock Tamiya ESC overheated even with a Sport Tuned. No issues when using the HW Quicrun.

As to the one-ways I have lots of experience with them. If we go back to 2006'ish I used it both in my B44 and XX4. Simply because the top dogs in the UK used them.

But when I put in a front diff I gotta say it was clearly better!
-much better control in the air (you only brake on the rear wheels with a one-way)

-smoother to drive = more consistent, just felt better

So all in all faster laps and average, at least for me.

I've never tried a torque splipper (one-way between front and rear), but since it's not used anymore I don't think it's an advantage. There's the new hype now with center diffs - but for high grip tracks from what I've heard you just have to push harder to be as fast as without it. I'm sure it's great on low/med grip tracks though.

This is what I think I'll try first then for the unis and Throp diffs outdrives:

1) Remove the 2mm pin from the dobone (using a Hudy tool)

2) "Coat" the ball end of the dogbone with one or more layers of shrinkwrap
3) Poke a hole in the wrap

4) Enter a custom made 2mm x 11mm pin(using a Hudy tool) http://www.ebay.com/itm/331397552951?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

The shrinkwrap of course won't be very durable, but then again it won't be cracking up like glue or epoxy could.

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I love the decal on the brace :) . I'd forgotten I'd done you some set plate covers already. I need to dig my hotshot out of the loft at some point to see if it might be possible to make some UJ's to fit in the front, with a UJ at both ends and a slider in the middle. I've already made several drive shafts for my other models (Half track, 4x4x4 lunch box, grapple skidder, 6x6 truck) based on the standard Tamiya 12mm universal joint used in a lot of their models, but I think this is too big to fit in the front hubs, and at the gearbox end. Something to look at if I ever run out of things to do ;).

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Update:

Thorp diffs (one will be used in another project):

IMG_7310.jpg

Using a special tool to remove the too short 2mm drive pins (still waiting for long rods to cut to correct lenght 11mm):

IMG_7317.jpg

Experimented with different thickness shrinkwrap and finally found one that gave the right result with two layers:
IMG_7318.jpg

A little trim + making hole for the pin:
92aee75f-5ee3-4e10-85f8-1ea7341c1023.jpg

We'll see how durable it'll be, but I'm kinda positive :rolleyes:

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I would machined new diff outdrives with the correct measurement and save the original ones.

Anyway you lucky man with two Thorp ball diffs. Where did you find them?

Max

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I would machined new diff outdrives with the correct measurement and save the original ones.

Anyway you lucky man with two Thorp ball diffs. Where did you find them?

Max

Doing that in the world's most expensive country would have cost me an arm and a leg :lol:

No, I'll try this simple fix first (I don't run this car much). If that don't work I'll use original dogbones, no problem - unis are no must.

I bought the diffs from cty300 on ebay, he seems to have a lot of them...

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Svein,

Wow, this is all very technical for me and all wonderful looking as well. I can't say that I will get to run my "Dreamshot" as it is more a work of assembled art to me, but you sure have me tempted to see what it can do. I will have a dig around for those Parma front arms as I just might have some hiding or I might take them from my Dreamshot as I don't see them as a huge advantage for the shelf. I know we were going to trade some things last year and I dropped that ball hugely as I don't know where the last part of the year went. If am I am not careful, I will have 2015 fly by me as well, this year I hope will be much less uneventful in my health.

It seems I have a perfect question for you, can the "longer" rear dogbones be used in the front if the steering knuckle/hub carrier is swapped out for the late model from the HS2 and Boomerang. If you remember, the Boomer and HS2 took all the same length dogbones on top of them being single piece construction. The SShot used two "colors" of dogbone as they were different lengths like the HS as it also used the same D parts knuckle for steering.

Thanks in advance for the answer on that, I usually use O rings to keep them in place, but you have to be careful if there is limited "compression" of the O ring as it just binds. I think some TRF sponge discs would be a great thing to keep the dogbones in their cups.

Well, I know where I will be this weekend, digging into all my parts so I can finish our trade if you still need/want some parts. I know your new JG bumper is smaller and I guess I need to figure out what I still need to make mine fit onto my HotShot 2 build that is trying to start.

Hope you are not too upset with me and my procrastination.

Chris

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Hi Chris!

No worries mate! :) Best of health in 2015!

I'll look into your dogbone tip if my mod fails. Learned from a vintage nutter today that the Thorp outdrives are brittle - so I might have to make a "protection ring" to press or glue to their outside.

Chris, that cool front swaybar solution and the Parma front arms I'd defo be keen on! :)

Link to those TRF sponge discs?

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