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graemevw

ORV rear arm pivot bearing mod

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Anyone mounted the orv rear arms on bearings?

Ive been drawing out ways, and think ive decided on an easiest/best solution, but before I start I wondered if anyone had already done it.

 

Ive heard rumours but seen no evidence.

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By the end of the week I should have something mocked up. Ill put the pics in here. Just been shopping and while walking around I realised I could simplify it even more.

 

Half the battle is not over thinking or over engineering it.

I am also trying to keep it copyable, but i think a lathe and a pillar drill will be needed with what I have in mind.

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On 8/16/2017 at 2:55 AM, graemevw said:

By the end of the week I should have something mocked up. Ill put the pics in here. Just been shopping and while walking around I realised I could simplify it even more.

 

Half the battle is not over thinking or over engineering it.

I am also trying to keep it copyable, but i think a lathe and a pillar drill will be needed with what I have in mind.

Well I'm keen :) And I have the required tooling ;) What have you come up with 

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Over this week I must have come up with 15 ways to do it. All a compromise of weight, reliability, strength.

As this is going in a truck ive gone with strength. 

Ive also tried to keep it simple. 

 

This means I want a through rod to keep the bearings properly in line.

I also want the same ID bearings each end which means heavier outside bearings.

I will start today.

 

I am going to make a threaded insert for inside the gearbox and put a m5 rod through.

Cut the stub off the inner end of the arm and push in a flanged 5x10. Cut the outer end off the arm and push in a flanged 5x14 (I need to cut the arm to double check sizes).

Put a spacer tube between the bearings inside the arm.

Make a 18mm disc (its a bit under I think) to go on the outer end to clamp the inner races and bearing tube.

original retainer hold the outer disc. The outer disc no longer rotates.

 

I did think about putting the bearings in the gearbox and a smaller metal stud in the arm and making a stud retainer for the outer. Can use lighter bearings and no steel harware. But there is much more chance of it getting knocked out of line and trying to bind the bearings.

 

Ive thought about many ways to do both these ideas but for my use, ill go with the first description. 

Only 3 easy pieces to make, 4 bearings, a bit of stud and a bit of tube. Should be strong and reliable even if there are lighter and more elegant ways.

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Made the center piece today. Drilled out a rear arm. Im a bit commited to 5x10 inner bearings now. 5x9 would probably fit better but they are only 3mm wide while the 10's are 4mm wide. I thought the extra width was worth it.

Now im not so convinced. Either should work though.

Ill order the bearings and once they arrive (mid week?) post pics of it all fitted up (or pics of the mess I made if it doesnt work).

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Well, its all done, apart from the fact I have no M5 nuts.

I had planned to thread the support discs but i want to be able to repeatedly strip it and dont like alloy nuts.

 

I cut the inner nubs off the arms, took 2mm of the inner length too. I then drilled the inner end 10mm and popped in a 10x5 flanged.

I cut the outer end of the arm along with the little spacing nubs. A 5x13 is a touch loose. I could use a 14 bearing and drill it out, but i think ill epoxy the 13mm in.

The bits of biro tube are makeshift spacers.

 

The center alloy piece sits inside the gearbox. It protrudes through the side plates and has seats for the inner arm bearings inner races. I will thread lock the stainless stud in. I will put a locking screw in from the outside of the gearbox so the whole spindle is locked from rotation.

The outer discs fit inside the original retainers and also have a seat for the bearings inner race.

I also shaved down the arms as they are very close to the chassis.

It works great, just need the nuts and ill fit it all properly.

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I now cant help but consider drilling all the front arms out and putting 4x7 flanged bearings in them too.

Silly, overkill, but I remember from my old monster beetle what all that horrid front end slop was like.

 

Thoughts?

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Also, are you planning on putting together kits for sale???  I'd be interested!  

Terry

 

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Those kits dont look like they use any bearings.

 

I hadnt thought about offering a kit, I may be able to though. Not sure if it would be too expensive to be worthwhile.

What would you be interested in. 

1. Just the turned parts.

2. All the metal work and bearings. 

3. Everything including modified rear arms.

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29 minutes ago, graemevw said:

Those kits dont look like they use any bearings.

 

I hadnt thought about offering a kit, I may be able to though. Not sure if it would be too expensive to be worthwhile.

What would you be interested in. 

1. Just the turned parts.

2. All the metal work and bearings. 

3. Everything including modified rear arms.

Yeah, they didn't mount bearings, only provided the "through-shaft" like yours.  

As for a Kit, I'd be interested in all the metal parts minus the Arm Holders that come with the Frog...  I can provide those, the bearings and the modified Arms...

Terry

 

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Awesome project..

I remember seeing a similar mod done on some of the senior racers Frogs when I first started racing.. They just used a piece of 5mm brass tube that passed through the arms and had body pins to hold it in place on the outside.. Instead of turning up a bushing for the Frogs outer pivot bracket, they just made a second bracket out of aluminium that was the same shape as the Frogs pivot bracket, and drilled a 5mm hole in the centre and screwed both pieces to the chassis... I have no idea if it had bearings in the arms, or what was done inside the gearbox though..

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I was going to make new plates, but I thought this was was easier to clamp all the inner races together.

There is absolutely no slop in this set up at all.

All a little pointless on a garden basher truck, but its a bit of fun.

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As with many home made hop-ups from back in the day, you used what you had, and making a second set of pivot plates could be done quite easily with basic hand tools..

If you have access to a lathe and can turn up some bushings then why not..

CRP also made a more basic hop-up to remove some of the slop from the ORV rear suspension.. It consisted of a plastic / nylon bushing that went into the gearbox that increased the contact area of the inner arm pivot inside the gearbox.. It also had some plastic / nylon outer pivot brackets similar to those on the Blackfoot / Monster Beetle..

I noticed that when I was rebuilding some of my Frogs that on some of them, someone had placed a piece of brass tube inside the gearbox pivot point that served the same basic purpose as the CRP bushing of increasing the surface area on the inner pivot and reducing some of the slop..

http://www.rcchopshop.com/crp/1606.html

 

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I considered putting a needle roller bearing in the gearbox and leaving the inner arm section stock. 

Lots of different ways to do it.

 

Thinking about the folk who asked for parts, as im in the uk, im not sure it would be cost effective.

 

Its easy enough to copy though. 

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Ok, ill look into it more.

Ill see what the various options take in time, and what they weigh for shipping, and see if I can give a few options. 

 

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I got this all finished today, ill put some pics up tomorrow.

No shocks on it yet but wheels are on. The whole back end, on these bearings and with the screwed diff feels sooooo slinky. It is effortless, rock solid and just feels indestructible. 

 

Not sure on doing kits still, fair bit of fettling and messing about to get it all together. If I do, it would probably be best to do a run of say 10, will cut down machining time/cost and as I need to buy materials the same (small) amount of metal will do all 10.

If I do, it may be a couple of weeks. Im still recovering from spinal surgery so standing over the lathe for a day isnt ideal yet.

 

Now the rear end is lovely, it really does highlight the clonky, loose, lets face it awfull front end.

Its alot of bearings to do all the front arms though but there is no way I can leave it as it is. Might try shimming it, maybe bushing the arms too. Not sure, got to try something though!

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Out of interest, I have a rererere orv and find the torque tuned motor slightly catches the right arm. I remedied with a knife and sand paper and basically removed material of the arm. Any one else picked up on it?

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I just put a torque tuned in mine today.

it JUST touches the motor when the arm is fully down.

I will also be shaving the arm down a little.

I haven't tried fitting the stock motor though, have you tried both? Is the TT slightly fatter?

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On ‎23‎/‎08‎/‎2017 at 0:38 AM, Frog Jumper said:

Also, are you planning on putting together kits for sale???  I'd be interested!  

Terry

 

I'd be interested too. :)

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