Kraton Exb 8s receiver box fitting issue

[Standrew]

Got the Kraton EXB 8s yeateday, looking to fit a Savox SW0241MG Jumbo Waterproof High Voltage Servo - 40KG.... Thought this would be simple, fitted the servo saver and checked that everything aligned into the chassis before fitting esc, receiver etc..... Fine out the screw holes don't line up underneath. They are out by about a quarter inch. That's with the servo saver axle in place and it sat correctly in the chassis.

Taken apart servo saver, Re done, no real way of doing the servo saver wrong from what I can see. Just won't line up to the receiver holes like the Savox 5th scale isn't designed to fit.

Any ideas?

 

[Rcproponent]

Got the Kraton EXB 8s yeateday, looking to fit a Savox SW0241MG Jumbo Waterproof High Voltage Servo - 40KG.... Thought this would be simple, fitted the servo saver and checked that everything aligned into the chassis before fitting esc, receiver etc..... Fine out the screw holes don't line up underneath. They are out by about a quarter inch. That's with the servo saver axle in place and it sat correctly in the chassis.

Taken apart servo saver, Re done, no real way of doing the servo saver wrong from what I can see. Just won't line up to the receiver holes like the Savox 5th scale isn't designed to fit.

Any ideas?

Please post pictures of what you mean if you can?

 

[Standrew]

Here you go, picture of servo, servo sat in the chassis with the servo saver axle in place and straight as you can. Picture underneath of the screw holes, in which you can only just see the hole of the receiver. If I take off the axle you see a little more but not enough to use. Stripping the servo saver down, removing the springs, so tight as, with screws buttoned up tight too, and they still don't line up. At a loss!

 

[Rcproponent]

Here you go, picture of servo, servo sat in the chassis with the servo saver axle in place and straight as you can. Picture underneath of the screw holes, in which you can only just see the hole of the receiver. If I take off the axle you see a little more but not enough to use. Stripping the servo saver down, removing the springs, so tight as, with screws buttoned up tight too, and they still don't line up. At a loss!

View attachment 134702

View attachment 134703

View attachment 134704

that’s a strange one..

 

[steveoooo]

Loosen the Servo on the 4 mounting points .... mount the reciever box loosely as the bolts will line up better ... then tighten it all down

 

[Standrew]

Thanks Steveoo for the response. The loosening of the servo wouldn't help, the holes are off the other way. In the pictures I've attached the receiver box to the chassis, then the next is the servo saver aligned when I put it in place, which doesn't fit. Should just drop into place with the servo saver axle in the hole. Not included that as it obscures the holder underneath, which shows its getting in the way. For me... Either the servo is to big, as in the height to where it connects too the servo saver or the chassis holes are wrong, which would seem very odd. Not sure why Savox would change the size of their servos, its a Jan 2021 batch on the box. Not sure if that matters.

 

[Jimbobjr]

Servo saver bolt is bottoming out in the shaft before the saver is completely down on the shaft making the whole thing too long. There might be an aluminum washer in your kit to take this up or add your own. Another option is making the screw a little shorter.

 

[Standrew]

Servo saver bolt is bottoming out in the shaft before the saver is completely down on the shaft making the whole thing too long. There might be an aluminum washer in your kit to take this up or add your own. Another option is making the screw a little shorter.

Thanks Jimbobjr for the response. Was thinking something the same.

At the moment if I strip it down to just the fixed parts, removing springs, plastic holders leaving just the servo saver shaft, servo save axle and servo 15T adaptor... Per the picture. It still doesn't fit and this is the shortest it'll go for the gap available... Which is just wrong. Just frustrating for me as unless I get into adjusting things it should just fit. Not taking a dremel to the axle holder or redoing the holds in the chassis... Can try and redo the holes in the receiver box but it's meshed and won't be string enough. Ordered a couple of new servos, 1/6th and another 1/5th. As at the moment this is nothing better than taking space up and distracting from my dual motor GT build

My money is on the servo being larger than it should be, holes in the chassis are machined and tooled for every unit, won't be that. Other than that it could be the servo saver isn't right, but again mass produced and standard.

 

[HOSS]

Thanks Jimbobjr for the response. Was thinking something the same.

At the moment if I strip it down to just the fixed parts, removing springs, plastic holders leaving just the servo saver shaft, servo save axle and servo 15T adaptor... Per the picture. It still doesn't fit and this is the shortest it'll go for the gap available... Which is just wrong. Just frustrating for me as unless I get into adjusting things it should just fit. Not taking a dremel to the axle holder or redoing the holds in the chassis... Can try and redo the holes in the receiver box but it's meshed and won't be string enough. Ordered a couple of new servos, 1/6th and another 1/5th. As at the moment this is nothing better than taking space up and distracting from my dual motor GT build

My money is on the servo being larger than it should be, holes in the chassis are machined and tooled for every unit, won't be that. Other than that it could be the servo saver isn't right, but again mass produced and standard.

View attachment 134844

I assume you tried this with both#6&#5 Tray's.. I definitely would run 60kg or high for your servo..big truck big tires

 

[Standrew]

My replacement will be a 65kg, hopefully it'll fit without an issue. Got the Savox as it was available and cheap to get it up and running. The 1/6 receiver box is too small for the Savox servo, so was an option too pick the wrong one.

Know parked it in the corner of my garage for another day. Back to my GT speed run build for the summer.

 

[Jimbobjr]

Looks like the savox is a few mm longer than the one I’m using. May be why it doesn’t work.
I’m running the spt.

 

[SrC]

Are you using the correct RX box to mount this servo?

RECEIVER BOX (ARA320553) | ARRMA - Designed Fast, Designed Tough (arrma-rc.com)

 

[DanenGraham]

The entire saver needs to be down farther, toward the servo. The bolt has got to be bottoming out, you need to add washers, add a spacer, cut the bolt, or get a new bolt. I just got my Hobbystar servo mounted up, and the screw is at least 1/8" to long in the new servo. I added 6 small lock washers and the normal washer that was already there. Its not perfect, and I have played back and forth between 6-7. If I go to 7, the reverse thread backout plug will not set down in the saver far enough because it hits the head of the screw, thus, the bearing and axle shaft also set out farther outside the saver. Dropped it back down to 6 washers, and now the bearing and axle on the front are in a better position (but still slightly past flush the face of the saver). But the back side of the enter saver isn't seated as far down.

The servo saver right now, does have a little bit of play when going from left to right. So I may try to go back to 7 washers to see if that isn't better.

I don't like the washers, but they do allow me to adjust it fairly easy and should work. I would prefer a shorter bolt, a solid spacer, or just cut my bolt.


Per the Diagrams posted above. They both have about 17mm (16.7 vs 17) from the flange, meaning the actual top/post/mount is the same distance from the box, and the extra length would be going toward the rear and into the Receiver box. You might have to trim the receiver box out possibly but your mounting height should be the same.

 

[Standrew]

Looks like the savox is a few mm longer than the one I’m using. May be why it doesn’t work.
I’m running the spt.

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I think you are spot on Jimbobjr. I spent time checking this out and comparing servo sizes. Not much in it 2.6mm, I'd say from the flang to the tip of the cog. My Savox also has zero room to move, so can't trim the box to move it back. Funnily enough I order the SPT version as the resoacement Feel better it'll fit now, just a 2 week delivery.

Cheers

The entire saver needs to be down farther, toward the servo. The bolt has got to be bottoming out, you need to add washers, add a spacer, cut the bolt, or get a new bolt. I just got my Hobbystar servo mounted up, and the screw is at least 1/8" to long in the new servo. I added 6 small lock washers and the normal washer that was already there. Its not perfect, and I have played back and forth between 6-7. If I go to 7, the reverse thread backout plug will not set down in the saver far enough because it hits the head of the screw, thus, the bearing and axle shaft also set out farther outside the saver. Dropped it back down to 6 washers, and now the bearing and axle on the front are in a better position (but still slightly past flush the face of the saver). But the back side of the enter saver isn't seated as far down.

The servo saver right now, does have a little bit of play when going from left to right. So I may try to go back to 7 washers to see if that isn't better.

I don't like the washers, but they do allow me to adjust it fairly easy and should work. I would prefer a shorter bolt, a solid spacer, or just cut my bolt.


Per the Diagrams posted above. They both have about 17mm (16.7 vs 17) from the flange, meaning the actual top/post/mount is the same distance from the box, and the extra length would be going toward the rear and into the Receiver box. You might have to trim the receiver box out possibly but your mounting height should be the same.

Thanks DanenGraham for the detailed response.

I spotted that it wss a mm or so too long. Didn't try your tip, as I'd stripped the servo down to see if it physically would fit. As Jimbobjr noticed the Savox compared with the SPT is slightly smaller. As you say flang to tip is 17mm from flang to servo top plus the cog 8.6mm, 25.6mm compared with the SPT of 23.5. I think Savox this year change the size of the servo, as I've seen a YouTube guy us my same servo and it fits, batch number 202009, mine is 202101... The SPT, should be the same as a Savox, just unbranded.

I'll use your washer tip for sure, I'd have thought it needs to be tight with no movement.

 

[Jimbobjr]

I know lots of guys use the Primal RC 1/5 scale servo as well as the JX. I’ve had the SPT in mine for around a year or so with no issues. I’m running it at 8.4 volts as well. The saver was very tight to get on. So much so I thought it was a different spline. They are both the same though. Someone said the newer models are 23t so that might also be a concern. Pretty sure the my spectrum and spt are 25t.

 

[BryanD101]

I think you are spot on Jimbobjr. I spent time checking this out and comparing servo sizes. Not much in it 2.6mm, I'd say from the flang to the tip of the cog. My Savox also has zero room to move, so can't trim the box to move it back. Funnily enough I order the SPT version as the resoacement Feel better it'll fit now, just a 2 week delivery.

Cheers

Thanks DanenGraham for the detailed response.

I spotted that it wss a mm or so too long. Didn't try your tip, as I'd stripped the servo down to see if it physically would fit. As Jimbobjr noticed the Savox compared with the SPT is slightly smaller. As you say flang to tip is 17mm from flang to servo top plus the cog 8.6mm, 25.6mm compared with the SPT of 23.5. I think Savox this year change the size of the servo, as I've seen a YouTube guy us my same servo and it fits, batch number 202009, mine is 202101... The SPT, should be the same as a Savox, just unbranded.

I'll use your washer tip for sure, I'd have thought it needs to be tight with no movement.

I have the exact same issue. I bought the same servo from the youtube video after I bought an even bigger server before that, only to find out that it still doesn't fit..lol

Did the new servo that you bought fit? I may try the washer method also.

 

[Standrew]

I have the exact same issue. I bought the same servo from the youtube video after I bought an even bigger server before that, only to find out that it still doesn't fit..lol

Did the new servo that you bought fit? I may try the washer method, but I'm also considering just using some self drilling screws in frustration.

Hi BryanD101,

The replacement worked perfectly, tight but just on the right side so no movement. Didn't need any washers either with this one. Also got a couple from China and a 7th scale one of I ran into 5th scale servo issues. More money than sense

Below works.

ANNIMOS 60KG Digital Servo 8.4V High Voltage Stainless Steel Gear Large Torque High Speed Waterproof Baja Servos - 180 Degrees​

 

[BryanD101]

Hi BryanD101,

The replacement worked perfectly, tight but just on the right side so no movement. Didn't need any washers either with this one. Also got a couple from China and a 7th scale one of I ran into 5th scale servo issues. More money than sense

Below works.

ANNIMOS 60KG Digital Servo 8.4V High Voltage Stainless Steel Gear Large Torque High Speed Waterproof Baja Servos - 180 Degrees​

Awesome! I'll check out that one.. Thanks alot

 

[BryanD101]

Hi BryanD101,

The replacement worked perfectly, tight but just on the right side so no movement. Didn't need any washers either with this one. Also got a couple from China and a 7th scale one of I ran into 5th scale servo issues. More money than sense

Below works.

ANNIMOS 60KG Digital Servo 8.4V High Voltage Stainless Steel Gear Large Torque High Speed Waterproof Baja Servos - 180 Degrees​

You are correct Sir. Fit like a tight glove