RCCrawler Forums

themerc64 · 03-07-2007, 04:38 AM

Here are a few ideas for a simple low budget crawler conversion for the HPI WK. My plan was to use as much of the original model as possible, including electronics. Also to try to make the conversion without any cutting or drilling, so those without the tools or skills could make this an easy build. I also tried to make sure that all needed parts are readily available from most any RC outlets.
Sorry this is not a step by step narrative, but I think most of you will figure it out from the pictures. I will try to update the details when I get some time. Also search the other WK threads for some more great ideas. Maybe we will get a WK section on the forum with all these good ideas.

To start with... Prices are from Tower Hobbies and can be found for less online

(1) HPI 10820 Wheely King RTR $189.99 I bought two for $360 out the door, locally

First… Making the WK 4WD. Here is the parts list for the 4WD conversion… Prices are from Tower Hobbies and can be found for less online

(1) HPI A431 Diff Case $4.79
(1) HPI A850 Diff Bevel Gear Set $4.79
(1) HPI A855 Diff Final Gear Set $5.79
(1) HPI 6819 Silicone O-Ring P-3 (RED/5pcs) $1.45
(1) HPI 86810 Gear Shaft 5x6x29mm $7.69
(1) HPI 86813 Drive Shaft 6x82 (2pcs) $12.99
(2) 10x15x4 Ball Bearings $0.99ea
(4) 5x11x4 Ball Bearings $0.99ea

Parts Total for this step $37.50

Second… Making the WK a Crawler. Here is the parts list for the Crawler conversion… Prices are from Tower Hobbies and can be found for less online

(2) Traxxas #2680 Screws, 3x25mm RH ST (6) $1.45 x2
(1) Traxxas #4951 Half shafts, long (heavy-duty) (external- splined (2) & Internal-splined (2))/metal u-joints (4) $7.69
(2) Traxxas #4928X Differential output yokes, heavy-duty (2)/set screw yoke pins, M4/10(2) $4.79 x2
(2) Traxxas #5138 Turnbuckles, 106mm (front tie rods) (2) (Includes installed rod ends and hollow ball connectors) $8.59 x2
(2) Traxxas #5139 Turnbuckles, 116mm (rear toe control links) (2) (Includes installed rod ends and hollow ball connectors) $8.59 x2
(1) HPI 6993 Spur Gear 93 Tooth (48 Pitch/Carbon Fiber) $3.89
(2) Tamiya 9804179 Lower Suspension Stay from TLT Kit $2.79
(1) Integy Matrix 55T lathe Motor $18.49

Parts Total for this step $79.70

Grand Total so far, less shipping and taxes $307.19 and RTR too!

Third… Whoops, did I say No Cutting?

I ended up modifying the servo mount so I could swap the servo to the other side of the chassis and keep the stock linkage. Very easy to do, just mirror the stock cutout on the opposite side of the mount and shave down the lugs where the servo attaches to the mount. You need the servo to set back in some so the servo horn will clear the inside of the chassis. A small mod is needed to the servo horn too, so it will clear the chassis. I will get some details up on that soon in case the pictures don’t give you the idea.
I also am still looking for a part number and or source for the lower steering link. It needs to be longer due to the stretched wheelbase. A 3x150mm threaded link will be needed, or just fabricate a link of your own. As you can see in the pics, I have just extended the link on the axle end. This will be changed out before it sees any use.

More to come…

chip cross · 03-07-2007, 04:52 AM

sweet how does it crawl i got one waiting for parts from lhs to make it a 4x4

themerc64 · 03-07-2007, 04:55 AM

Here are a few more...

themerc64 · 03-07-2007, 05:02 AM

Here are a couple more...

NickRummy · 03-07-2007, 06:49 AM

Looks good! What did you do for the upper shock mounts? Also it looks like both your upper links and lower links mount to the same spot on the chassis? I like how you flipped the shock/link mounts on the axle. I had mine flipped too but I ended up putting them back and mounting my lower links on the bottom part of the axle. I'm thinking the links being on the bottom might help the truck slide over rocks better. When I had my links mounted to the top of the axle like yours it seemed like it might be easy for the axle to get hung up.

davcom · 03-07-2007, 07:10 AM

very cool.

themerc64 · 03-07-2007, 09:40 AM

This not being a serious crawler I was not planning on going all out on it. I am looking to make a functional skid plate from something easy to find around the house. Nothing is set in stone yet, so the link positions could change. The lower links were to be mounted lower on the chassis, but the links bound up really badly. The axle link mounts could be used differently as seen in some of the other WK threads. This is still a work in progress and updates will be posted. Thanks for the comments guys...

cotharyus · 03-07-2007, 10:33 AM

What is the bracket you are using to attach the top links to the axle? I struggled with this quite a bit, and settled on something that I'm not entirely happy with because I couldn't find any think channel material to fab something with laying around.

NickRummy · 03-07-2007, 11:05 AM

Quote:

Originally Posted by cotharyus

What is the bracket you are using to attach the top links to the axle? I struggled with this quite a bit, and settled on something that I'm not entirely happy with because I couldn't find any think channel material to fab something with laying around.

http://www2.towerhobbies.com/cgi-bin...?&I=LXGKG9&P=7

pbfrk4life · 03-07-2007, 12:36 PM

WOW! Great thread!

What is the total wb now? How much did all this end up costing?

Kranberry · 03-07-2007, 04:06 PM

how much did it end up costing ya for the conversion?

Randy77 · 03-07-2007, 05:18 PM

great info, been looking at the WK as a possible truck for Momma to play with.

themerc64 · 03-08-2007, 11:45 AM

Chip, It's not running yet.

Nick, 3x25mm screws into existing chassis holes, The links on the chassis worked out pretty good that way, and I will probably remove the lower tabs on the axles, but I am going to wait until I make the skid plate first.

cotharyus, It is a TLT lower link mount.

pbfrk4life, WB is just over 12" and I still need to add the cost up. I upgraded the motor to a 55T Integy, so I need to figure that and whatever I use for the skid plate in. I will update the cost soon. I am building a couple other rigs at the same time, so I get sidetracked too easy!

Thanks to everyone else for the comments, share the good!

warp speed · 03-08-2007, 11:57 AM

I know I have not posted much on this site, but I have been lurking longer than I have been registered. I have the Wheely king and love it. I too also stretched mine out to make it a crawler. I just made links longer than the stock ones. I was looking at the way yours is stretched and where you have your links positioned. I think you will find that as you compress one corner, it will cause the axle to turn, or not stay straight in relation to the frame. Almost as if you turned the wheels left or right. This is caused by both upper and lower links sharing the same pivot point, and both links mounted on top of the axle.
Otherwise it looks good.

NickRummy · 03-08-2007, 11:59 AM

I used 3mm hardware too. I might change my lower mounting points but i'm not sure yet. I'll have new shocks in a few days. I put it through it's paces last night

Big Mike · 03-08-2007, 01:36 PM

You're gonna hang up a lot here, where I've put arrows:

Also, the inboard link mounts being on the same plane is going to bind up the suspension. But your only option looks like moving them back to the original mounting holes. Or raising the top inboard mount points - IF there's a spot to move them to.
It also looks like you could shorten the upper links some and make the axle rotate inward and sit straight up and down - so the input shafts are not canted upward like they are now.
If you're ok with it the way it is, you've got the lower holes to mount a skidplate.
Looks real good so far. Just the wheelbase stretch should make it perform a lot better.
Looks like the stock WK chassis is not going to be very modifiable. At least you can spot new holes in a stock TLT chassis...

FossilJunkie · 03-08-2007, 01:47 PM

Quote:

Originally Posted by warp speed

I know I have not posted much on this site, but I have been lurking longer than I have been registered. I have the Wheely king and love it. I too also stretched mine out to make it a crawler. I just made links longer than the stock ones. I was looking at the way yours is stretched and where you have your links positioned. I think you will find that as you compress one corner, it will cause the axle to turn, or not stay straight in relation to the frame. Almost as if you turned the wheels left or right. This is caused by both upper and lower links sharing the same pivot point, and both links mounted on top of the axle.
Otherwise it looks good.

I'ma have to agree here. Do a quick search on 4-link design, everything you need to know has been posted, and helped me a lot when I build my first one. Best way to mount your links is equal spacing (same distance between mounts on the axle and chassis) Other than that, yea, looks like a skidplate is a must, yer gunna get caught up of that piece in the middle a lot.

Big Mike · 03-08-2007, 01:47 PM

I'm confused now -
It looks like there are six links in the front, four in the back? Is this an optical illusion or something?

FossilJunkie · 03-08-2007, 01:49 PM

Quote:

Originally Posted by Big Mike

I'm confused now -
It looks like there are six links in the front, four in the back? Is this an optical illusion or something?

I was wondering the same thing...

NickRummy · 03-08-2007, 01:50 PM

Quote:

Originally Posted by Big Mike

I'm confused now -
It looks like there are six links in the front, four in the back? Is this an optical illusion or something?

One in the front is a steering link.

03-07-2007, 04:38 AM	#1
themerc64 Rock Crawler Join Date: Jul 2005 Location: Rathdrum, ID USA Posts: 549	WK to Crawler Conversion… Cheap & Simple! Here are a few ideas for a simple low budget crawler conversion for the HPI WK. My plan was to use as much of the original model as possible, including electronics. Also to try to make the conversion without any cutting or drilling, so those without the tools or skills could make this an easy build. I also tried to make sure that all needed parts are readily available from most any RC outlets. Sorry this is not a step by step narrative, but I think most of you will figure it out from the pictures. I will try to update the details when I get some time. Also search the other WK threads for some more great ideas. Maybe we will get a WK section on the forum with all these good ideas. To start with... Prices are from Tower Hobbies and can be found for less online (1) HPI 10820 Wheely King RTR $189.99 I bought two for $360 out the door, locally First… Making the WK 4WD. Here is the parts list for the 4WD conversion… Prices are from Tower Hobbies and can be found for less online (1) HPI A431 Diff Case $4.79 (1) HPI A850 Diff Bevel Gear Set $4.79 (1) HPI A855 Diff Final Gear Set $5.79 (1) HPI 6819 Silicone O-Ring P-3 (RED/5pcs) $1.45 (1) HPI 86810 Gear Shaft 5x6x29mm $7.69 (1) HPI 86813 Drive Shaft 6x82 (2pcs) $12.99 (2) 10x15x4 Ball Bearings $0.99ea (4) 5x11x4 Ball Bearings $0.99ea Parts Total for this step $37.50 Second… Making the WK a Crawler. Here is the parts list for the Crawler conversion… Prices are from Tower Hobbies and can be found for less online (2) Traxxas #2680 Screws, 3x25mm RH ST (6) $1.45 x2 (1) Traxxas #4951 Half shafts, long (heavy-duty) (external- splined (2) & Internal-splined (2))/metal u-joints (4) $7.69 (2) Traxxas #4928X Differential output yokes, heavy-duty (2)/set screw yoke pins, M4/10(2) $4.79 x2 (2) Traxxas #5138 Turnbuckles, 106mm (front tie rods) (2) (Includes installed rod ends and hollow ball connectors) $8.59 x2 (2) Traxxas #5139 Turnbuckles, 116mm (rear toe control links) (2) (Includes installed rod ends and hollow ball connectors) $8.59 x2 (1) HPI 6993 Spur Gear 93 Tooth (48 Pitch/Carbon Fiber) $3.89 (2) Tamiya 9804179 Lower Suspension Stay from TLT Kit $2.79 (1) Integy Matrix 55T lathe Motor $18.49 Parts Total for this step $79.70 Grand Total so far, less shipping and taxes $307.19 and RTR too! Third… Whoops, did I say No Cutting? I ended up modifying the servo mount so I could swap the servo to the other side of the chassis and keep the stock linkage. Very easy to do, just mirror the stock cutout on the opposite side of the mount and shave down the lugs where the servo attaches to the mount. You need the servo to set back in some so the servo horn will clear the inside of the chassis. A small mod is needed to the servo horn too, so it will clear the chassis. I will get some details up on that soon in case the pictures don’t give you the idea. I also am still looking for a part number and or source for the lower steering link. It needs to be longer due to the stretched wheelbase. A 3x150mm threaded link will be needed, or just fabricate a link of your own. As you can see in the pics, I have just extended the link on the axle end. This will be changed out before it sees any use. More to come… Attached Images Last edited by themerc64; 03-11-2007 at 03:36 AM.

03-07-2007, 04:55 AM	#3
themerc64 Rock Crawler Join Date: Jul 2005 Location: Rathdrum, ID USA Posts: 549	Some more WK pics... Here are a few more... Attached Images

03-08-2007, 11:45 AM	#13
themerc64 Rock Crawler Join Date: Jul 2005 Location: Rathdrum, ID USA Posts: 549	Let me get caught up... Chip, It's not running yet. Nick, 3x25mm screws into existing chassis holes, The links on the chassis worked out pretty good that way, and I will probably remove the lower tabs on the axles, but I am going to wait until I make the skid plate first. cotharyus, It is a TLT lower link mount. pbfrk4life, WB is just over 12" and I still need to add the cost up. I upgraded the motor to a 55T Integy, so I need to figure that and whatever I use for the skid plate in. I will update the cost soon. I am building a couple other rigs at the same time, so I get sidetracked too easy! Thanks to everyone else for the comments, share the good!

03-08-2007, 11:57 AM	#14
warp speed Newbie Join Date: Feb 2007 Location: Grand Forks AFB Posts: 10	Link Set up I know I have not posted much on this site, but I have been lurking longer than I have been registered. I have the Wheely king and love it. I too also stretched mine out to make it a crawler. I just made links longer than the stock ones. I was looking at the way yours is stretched and where you have your links positioned. I think you will find that as you compress one corner, it will cause the axle to turn, or not stay straight in relation to the frame. Almost as if you turned the wheels left or right. This is caused by both upper and lower links sharing the same pivot point, and both links mounted on top of the axle. Otherwise it looks good.

03-08-2007, 01:36 PM	#16
Big Mike I wanna be Dave Join Date: Oct 2006 Location: Martinsburg WV Posts: 2,781	You're gonna hang up a lot here, where I've put arrows: Also, the inboard link mounts being on the same plane is going to bind up the suspension. But your only option looks like moving them back to the original mounting holes. Or raising the top inboard mount points - IF there's a spot to move them to. It also looks like you could shorten the upper links some and make the axle rotate inward and sit straight up and down - so the input shafts are not canted upward like they are now. If you're ok with it the way it is, you've got the lower holes to mount a skidplate. Looks real good so far. Just the wheelbase stretch should make it perform a lot better. Looks like the stock WK chassis is not going to be very modifiable. At least you can spot new holes in a stock TLT chassis... Last edited by Big Mike; 03-08-2007 at 01:44 PM.

03-07-2007, 04:52 AM	#2
chip cross ΜΟΛΩΝ ΛΑΒΕ Join Date: Dec 2006 Location: In tha Bush of Louisiana Posts: 4,343	sweet how does it crawl i got one waiting for parts from lhs to make it a 4x4 Last edited by chip cross; 03-07-2007 at 04:54 AM.

03-07-2007, 05:02 AM	#4
themerc64 Rock Crawler Join Date: Jul 2005 Location: Rathdrum, ID USA Posts: 549	And a few more... Here are a couple more... Attached Images

03-07-2007, 06:49 AM	#5
NickRummy RCC Addict Join Date: Aug 2005 Location: Akron Posts: 1,784	Looks good! What did you do for the upper shock mounts? Also it looks like both your upper links and lower links mount to the same spot on the chassis? I like how you flipped the shock/link mounts on the axle. I had mine flipped too but I ended up putting them back and mounting my lower links on the bottom part of the axle. I'm thinking the links being on the bottom might help the truck slide over rocks better. When I had my links mounted to the top of the axle like yours it seemed like it might be easy for the axle to get hung up.

03-07-2007, 07:10 AM	#6
davcom Newbie Join Date: Apr 2006 Location: Vestal Posts: 48	very cool.

03-07-2007, 09:40 AM	#7
themerc64 Rock Crawler Join Date: Jul 2005 Location: Rathdrum, ID USA Posts: 549	This not being a serious crawler I was not planning on going all out on it. I am looking to make a functional skid plate from something easy to find around the house. Nothing is set in stone yet, so the link positions could change. The lower links were to be mounted lower on the chassis, but the links bound up really badly. The axle link mounts could be used differently as seen in some of the other WK threads. This is still a work in progress and updates will be posted. Thanks for the comments guys...

03-07-2007, 10:33 AM	#8
cotharyus Quarry Creeper Join Date: Nov 2004 Location: Mid TN Posts: 411	What is the bracket you are using to attach the top links to the axle? I struggled with this quite a bit, and settled on something that I'm not entirely happy with because I couldn't find any think channel material to fab something with laying around.

03-07-2007, 12:36 PM	#10
pbfrk4life Pebble Pounder Join Date: Jan 2007 Location: Clovis Posts: 158	WOW! Great thread! What is the total wb now? How much did all this end up costing?

03-07-2007, 04:06 PM	#11
Kranberry RCC Addict Join Date: Aug 2006 Location: ****, SL,UT Posts: 1,610	how much did it end up costing ya for the conversion?

03-07-2007, 05:18 PM	#12
Randy77 Rock Stacker Join Date: Feb 2007 Location: Kingsport Posts: 55	great info, been looking at the WK as a possible truck for Momma to play with.

03-08-2007, 11:59 AM	#15
NickRummy RCC Addict Join Date: Aug 2005 Location: Akron Posts: 1,784	I used 3mm hardware too. I might change my lower mounting points but i'm not sure yet. I'll have new shocks in a few days. I put it through it's paces last night

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03-08-2007, 01:47 PM	#18
Big Mike I wanna be Dave Join Date: Oct 2006 Location: Martinsburg WV Posts: 2,781	I'm confused now - It looks like there are six links in the front, four in the back? Is this an optical illusion or something?

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