Jump to content
Toolmaker72

Sand scorcher on a king Blackfoot chassis

Recommended Posts

Just sharing a build that I’m doing.  I believe the chassis started out as a king Blackfoot.  A second hand purchase with front suspension missing.

I bought it for the double wishbone rear suspension gearbox that fits onto the orv chassis and then complete as a red monster beetle with a brushless motor.

Well I thought the wheel base looked better for a scorcher/ blitzer beetle hybrid build.

Parts are a mix and match to get things sitting right and working.

I had the random red front suspension tower to modify with shorter front shocks that fit nicely under the scorcher bonnet/hood.  The lower mounting point for the front dampers uses longer wishbone bolts I made from a m5 Allen bolt.  The lower bolts had worn through the plastic steering upright so that was repaired using a brass tube bush.  The original holes made larger to accept the tube and allow original lower wishbone bolts to be used.  The yellow cva dampers were made softer with 2 extra holes drilled through the piston/plunger (1.5mm).  

Rear red dampers were limited inside and outside  to shorten the stroke and give a level chassis but also stop the gearbox bottoming out on the floor.  Now I know the length required I think I’ll replace with yellow cva units to match the front.

Usual ballraced gearbox ready for the 2845 4370kv motor.  I’ve kept the small monster beetle brass drive pinion.  The extra revs the motor gives will more than compensate for the low gearing.  I’m hoping the wider track makes the chassis more stable for faster cornering speeds.  First run will be a regular 7.2v pack then if ok will try a 3s battery.

To mount the body, I’ve used the position on the orv chassis that the frog uses but with extended brass mounts.   The hole in the body is approx 5mm to the rear of the marked area used for a monster beetle fitment.  The front mount uses the original hole meant for a sand scorcher which is already there.   Roof body mount holes have been filled.  I’ve only just screwed and glued the body details on today so will let everything set glue wise before blending in ready for primer paint.

Wheels are white so I’m thinking a white body with either a scorcher inspired blue side panel or white with a yellow side panel to tie in the yellow cva dampers.

pictures below of the build so far

 

 

4E247C32-4884-4AC1-8E51-336EF88694BA.jpeg

0B0A9594-E5C4-4960-9E9C-31E80F8AC886.jpeg

  • Like 4

Share this post


Link to post
Share on other sites

Forgot to say the bump steer is horrendous using the standard steering parts.   I had already made a new Bush to help remove the massive play in the mechanism.  I might just centre mount the steering servo and steer directly off that as the monster beetle.    
Any better ideas are more than welcome 😊

Share this post


Link to post
Share on other sites
18 minutes ago, Frog Jumper said:

Thank you 👍.  I have those Parma  steering arms on a regular monster beetle and they do work well in reducing bump steer.  These later steering arms are so wrong.  I think first thing is remove the ball joint and raise it level with the joint on the chassis and go from there.  🤔

  • Like 1

Share this post


Link to post
Share on other sites

A couple of close up pictures of the stepped bolts I made to hold the damper in place.

Also I borrowed monster beetle uprights and steering knuckles from my bitsa mule to see if the they fit ok with the king Blackfoot wishbones.  Answer is yes.  Bump steer virtually gone as well.  I need to shorten the steering arms properly to adjust but I think it’s ok.  The monster beetle parts do give a little camber with the suspension compressed though so i suspect possible shorter upper wishbones are needed.  Im thinking of just centre mounting the steering servo as well so all that steering play can be lost.   No need for two servos anymore when using an esc.

9874BCA5-8242-44BB-8848-F6B63FB6BA4D.jpeg

65D5EF62-BDD6-4375-8B23-98B466F5165B.jpeg

1525646F-D9DC-4E96-9382-4E31F89BC6FC.jpeg

  • Like 1

Share this post


Link to post
Share on other sites

 Nope too much camber.  The wider wheels just make it worse.  Trying to keep things simple so reverted back to the king Blackfoot parts.  

The steering arms will have the ball joint raised.  I measured 20mm which is quite a bit but will see how it works once I make the little extension pieces. 

Share this post


Link to post
Share on other sites

The KBF uses the SBF hubs, and the SBF uses the BF sus arms, ie the BF hub should work with the KBF arms and therefore you can use the Parma bump steer knuckles???

Share this post


Link to post
Share on other sites
11 hours ago, Frog Jumper said:

The KBF uses the SBF hubs, and the SBF uses the BF sus arms, ie the BF hub should work with the KBF arms and therefore you can use the Parma bump steer knuckles???

The parts fit but the securing pivots holes are in slightly different positions which is giving me camber the wrong way unless I make shorter top wishbones to counteract the excessive camber. 
Even the standard set up induces camber when the suspension is compressed but at a smaller amount.  Standard Blackfoot front suspension stays nice and flat by comparison.  They clearly have a shorter top wishbone. I’ll raise the ball joints on the  steering knuckles and go from there.  It will probably be a bit weak that high and no doubt mean a pair of new steering knuckles

  • Like 1

Share this post


Link to post
Share on other sites

I managed to  make a couple of extensions to the steering knuckles.  Removing the original ball joint is a drill out job as the part has a hidden collar and is moulded around it hence it can’t be unscrewed or simply tapped out.  Pictures below show the extensions fitted.  As suspected they flex. So I need to make from a bit of aluminium incorporating a web and a slight crank away from the tyre.  

98068A66-7702-40AD-A8DF-EC946B5FADEB.jpeg

EBBB008F-27D7-4F88-BA9F-F56FBABCE8ED.jpeg

BFAC4AA7-F06E-4422-A181-FC9CF7F3B7FC.jpeg

  • Like 1

Share this post


Link to post
Share on other sites

spacer.pngAlthough the extended parts flex due to being bolted to nylon they do get rid of the bump steer.

pictures below show wheel position with extended and compressed suspension with servo in same position.    Very pleased with that result.  Now to measure up and machine a tidy pair of steering knuckles 

 

0760D537-5165-4C78-85F9-36B57911B2AF.jpeg

7B639730-47ED-4D94-85B6-D25F4996EAF6.jpeg

  • Like 1

Share this post


Link to post
Share on other sites
38 minutes ago, Toolmaker72 said:

I managed to  make a couple of extensions to the steering knuckles.  Removing the original ball joint is a drill out job as the part has a hidden collar and is moulded around it hence it can’t be unscrewed or simply tapped out.  Pictures below show the extensions fitted.  As suspected they flex. So I need to make from a bit of aluminium incorporating a web and a slight crank away from the tyre.  

98068A66-7702-40AD-A8DF-EC946B5FADEB.jpeg

 

 

 

How tall are these extensions???

Great work BTW!

Thanks,

Terry

 

Share this post


Link to post
Share on other sites
25 minutes ago, Frog Jumper said:

 

How tall are these extensions???

Great work BTW!

Thanks,

Terry

 

20mm

  • Like 1

Share this post


Link to post
Share on other sites

Nice fix for the KBF bump steer. I did the same on my BF where the knuckles are easier as the connectors are screwed in.

52085655014_702a6e5aab_b.jpg

 

Share this post


Link to post
Share on other sites

I’m thinking now to use regular monster beetle steering knuckles because it’s only a 5mm extension needed and being a longer unit the it’s less stress on the pivot pin as the unit is pushed and pulled via the steering arm.  Also means I just need to make a pair of small brackets rather than spend a few hours machining.  The uprights will need to be cut so as the taller steering knuckles will fit which is the downside but they are a naff design anyway.   Hopefully will make these bits Monday when back at work 😊

Share this post


Link to post
Share on other sites

Monday was busy with an actual work repair 🙄😊.  This morning had a couple of hours to get as far as the pictures below.  Little brackets made from black nylon to blend in to the original plastic.  I need to secure these brackets with a couple of self tappers then finish mill the correct gap for the steering knuckle and drill a hole for the pivot pin.  Possibly shape the bracket to look similar to the original part.  Bit fiddly but getting there 😊

C2CEC99F-26FF-4812-A5E2-8F0536E9EA64.jpeg

DCE8C586-6F00-42A1-8F2B-EAE8E9234B6E.jpeg

CB56337D-5B80-466C-A0E8-DAF7777B70A8.jpeg

0DFD5009-0E55-4A24-A403-2A3224E97990.jpeg

Share this post


Link to post
Share on other sites

Secured the new brackets and finished the size for the steering knuckle to fit between.  Very pleased with the result.  Hopefully find time over the weekend and fit these to the chassis and see how it looks.

ADF83B60-3553-4A62-97DE-EDFD5AC98212.jpeg

41F2C465-546A-461B-87D1-875EEE0DE868.jpeg

073A2314-2584-4ADE-936B-39B21AFEDB3C.jpeg

1D7581E3-9566-405F-8084-5D068E45AEB3.jpeg

  • Like 2

Share this post


Link to post
Share on other sites

The mods to the front suspension and steering works lovely.  I’ve been chipping away with painting the body.  Nothing fancy but I think it looks effective.  Pictures of body so far.  Still need to complete the driver figure and a few body details but overall I’m happy with it.

957EAD00-1EFA-4982-8B6D-23D811F1EFAF.jpeg

46EE84C8-9977-4BDD-BF47-F0A17126C16A.jpeg

1A4ECFFC-CCCE-431B-9078-15479329CFC0.jpeg

1BC471E1-2200-4CBA-BE9E-09BA02013E7D.jpeg

79B923F4-BD3F-4F02-B319-DAA31CFC6592.jpeg

62BFBABC-5AA9-46F5-A9F8-44CB2BB6C332.jpeg

F0BAA5F1-82B2-4140-BC9C-42B5D917DAFA.jpeg

  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...