RPM arm 3s ‘bowing’ issue. Does 6s also bow?

[Velodromed]

When I did my recent long wheel base 3S build I put typhon rpm arms on. I already expected them to bow somewhat because the shorter ones on my granite do. However I did not expect them to bow in less than a month and so much. I mean it literally looks like the ass end is double smiling at me they have bowed so much

I’m building a notorious and I decided to get rpm arms for it. Do they bow on a 6S car as bad as they do on my 3s car? Is there anything that can be done to stiffen them up a bit, like boiling them and quenching them in cold water? I know that somewhat defeats the purpose of flexible RPM arms, but it’s really bad on my long armed 3s build. Bad to the point of interfering with suspension function, especially on the rear.

I will admit I’m a bit frustrated because the stupid things are pricey. I’m thinking I should’ve stuck with stock arms off of Jenny’s.

 

[Jackjax801]

I never noticed any bowing on my 3s Typhon with rpm arms but also never stored it on its wheels. Not sure if that's what's causing it. I've heard that boiling them will straighten them out, don't think it'll stop them from bowing again though. Someone on here said that they switch theirs from left to right occasionally, so it can bow in the other direction. A bit tedious but may be your best bet.

 

[Dan B.]

I will never run RPM arms on another truck. They all bow, and the heavier the rig gets (ie. 6s) the worse they are.
I know that a ton of people love them, but I’m not among them. I run the Traxxas HD arms and Team Associated Hard arms on those respective brands, as they are both vastly superior to the RPM ones, but on the Arrmas I choose the factory arms. If they break eventually they are cheap and quick to replace.

 

[Robbbbbb66]

When I did my recent long wheel base 3S build I put typhon rpm arms on. I already expected them to bow somewhat because the shorter ones on my granite do. However I did not expect them to bow in less than a month and so much. I mean it literally looks like the ass end is double smiling at me they have bowed so much

I’m building a notorious and I decided to get rpm arms for it. Do they bow on a 6S car as bad as they do on my 3s car? Is there anything that can be done to stiffen them up a bit, like boiling them and quenching them in cold water? I know that somewhat defeats the purpose of flexible RPM arms, but it’s really bad on my long armed 3s build. Bad to the point of interfering with suspension function, especially on the rear.

I will admit I’m a bit frustrated because the stupid things are pricey. I’m thinking I should’ve stuck with stock arms off of Jenny’s.

I will never run RPM arms on another truck. They all bow, and the heavier the rig gets (ie. 6s) the worse they are.
I know that a ton of people love them, but I’m not among them. I run the Traxxas HD arms and Team Associated Hard arms on those respective brands, as they are both vastly superior to the RPM ones, but on the Arrmas I choose the factory arms. If they break eventually they are cheap and quick to replace.

I don't have any experience with the 6s line RPM ( Stock ones seem strong enough), But my Kraton 8s would be not be runable without RPM arms, stock ones break on like a 2 foot jump for me on the K8. Kraton 8s RPM arms are bowing on the K8, But the ones on my Senton 3s, Typhon 3s and Slash are fine.

 

[Velodromed]

I never noticed any bowing on my 3s Typhon with rpm arms but also never stored it on its wheels. Not sure if that's what's causing it. I've heard that boiling them will straighten them out, don't think it'll stop them from bowing again though. Someone on here said that they switch theirs from left to right occasionally, so it can bow in the other direction. A bit tedious but may be your best bet.

Yup, I boil the ones on my granite and switch them when doing maintenance. But these typhons ones are bowing so bad it’s ridiculous. Mainly on the rear, so I may swap those with stock.

I used to store wheels up but recently moved the cars to a better storage area in the garage, which is more confined. I’ll go back to wheels up….

…yup, back to wheels up now lol. Here’s what they look like. I only completed this build a month back.

I don't have any experience with the 6s line RPM ( Stock ones seem strong enough), But my Kraton 8s would be not be runable without RPM arms, stock ones break on like a 2 foot jump for me on the K8. Kraton 8s RPM arms are bowing on the K8, But the ones on my Senton 3s, Typhon 3s and Slash are fine.

So you have rpm arms on your typhon and they don’t bow? The fronts are fine but the rear…man. Just a month old or so.

I will never run RPM arms on another truck. They all bow, and the heavier the rig gets (ie. 6s) the worse they are.
I know that a ton of people love them, but I’m not among them. I run the Traxxas HD arms and Team Associated Hard arms on those respective brands, as they are both vastly superior to the RPM ones, but on the Arrmas I choose the factory arms. If they break eventually they are cheap and quick to replace.

Thanks man. Maybe I’ll just use them as ‘training’ arms on the cars I let others drive since I have a couple sets. Or sell them since you’re right about some folks loving them and a couple are still packaged. Too late for the 6s ones though as I already mounted them, so back to my training arms theory since it’s my first 6s car and plan on jumping it.

 

[Crunchy Gears]

Yup, I boil the ones on my granite and switch them when doing maintenance. But these typhons ones are bowing so bad it’s ridiculous. Mainly on the rear, so I may swap those with stock.

I used to store wheels up but recently moved the cars to a better storage area in the garage, which is more confined. I’ll go back to wheels up….

…yup, back to wheels up now lol. Here’s what they look like. I only completed this build a month back.

View attachment 211561

View attachment 211562

So you have rpm arms on your typhon and they don’t bow? The fronts are fine but the rear…man. Just a month old or so.

Thanks man. Maybe I’ll just use them as ‘training’ arms on the cars I let others drive since I have a couple sets. Or sell them since you’re right about some folks loving them and a couple are still packaged. Too late for the 6s ones though as I already mounted them, so back to my training arms theory since it’s my first 6s car and plan on jumping it.

I'm gonna have to go look...but I don't think my Typhon arms are bowed . I didn't boil em tho

These arms are 6 months old. This pic is from a couple weeks ago before I destroyed my last CVD and started my 4s suspension conversion.


EDIT yeah they're straight.

You can see a slight bend in this one on the right. But that is from the turnbuckle it was attached to being bent 90° from a crash landing from 20 feet up onto blacktop

I'd say just don't boil em. The 3s car arms don't need it they're durable enough.

 

[Velodromed]

I'm gonna have to go look...but I don't think my Typhon arms are bowed . I didn't boil em tho

View attachment 211568
These arms are 6 months old. This pic is from a couple weeks ago before I destroyed my last CVD and started my 4s suspension conversion.

EDIT yeah they're straight. View attachment 211569

You can see a slight bend in this one on the right. But that is from the turnbuckle it was attached to being bent 90° from a crash landing from 20 feet up onto blacktop

I'd say just don't boil em. The 3s car arms don't need it they're durable enough.

How are the rear arms? Those are what’s bowing badly, not so much the front. Thanks bud!

I'm gonna have to go look...but I don't think my Typhon arms are bowed . I didn't boil em tho

View attachment 211568
These arms are 6 months old. This pic is from a couple weeks ago before I destroyed my last CVD and started my 4s suspension conversion.


EDIT yeah they're straight. View attachment 211569

You can see a slight bend in this one on the right. But that is from the turnbuckle it was attached to being bent 90° from a crash landing from 20 feet up onto blacktop

I'd say just don't boil em. The 3s car arms don't need it they're durable enough.

Oh, and here’s a shout out to those
GOOGLY EYES!! GOOGLY GOOGLY!!

 

[Crunchy Gears]

How are the rear arms? Those are what’s bowing badly, not so much the front. Thanks bud!

Oh, and here’s a shout out to those
GOOGLY EYES!! GOOGLY GOOGLY!!

Whatchu looking at!?

Sorry can't help ya with the rears. They're still sitting in a bag unused. They were out of stock when I widened the Granite last year and so I put stock Typhon arms on instead. Never broke em..broken everything but almost but it's not like all the weight is on the ass so I don't see how the rear arms would be any different?

 

[Adiabatic]

Haven't used them on an Arrma car but on other heavy 1/8 scale vehicles I had them bow. The biggest problem with them actually wasn't the bowing in storage but the high degree of deformation under running loads which caused other components to overextend and fail. Broken/bent shocks and bent/popped driveshafts were common.

 

[Roadkill69]

I never had a RPM arm bow or break.

 

[Velodromed]

Whatchu looking at!?

Sorry can't help ya with the rears. They're still sitting in a bag unused. They were out of stock when I widened the Granite last year and so I put stock Typhon arms on instead. Never broke em..broken everything but almost but it's not like all the weight is on the ass so I don't see how the rear arms would be any different?

Think it’s how the shock mount is placed. Thanks man!

Haven't used them on an Arrma car but on other heavy 1/8 scale vehicles I had them bow. The biggest problem with them actually wasn't the bowing in storage but the high degree of deformation under running loads which caused other components to overextend and fail. Broken/bent shocks and bent/popped driveshafts were common.

Thank you, I’ve heard that could be an issue as well.

 

[GRC]

Here’s what they look like. I only completed this build a month back.

View attachment 211561

View attachment 211562

Ha, that's nothing. You should see mine. Yes, the Typhon RPM arms bow. The Granite ones do also, but not as quickly since they're shorter. I just leave them bowed. The main difference is less ground clearance as they get more bowed. The camber also changes, but you can adjust accordingly. Bowed arms may actually keep you lower and increase handling performance, but to be honest, I don't notice much difference either way. I used to boil them and straighten them out, but the way I jump, they get bowed again in no time. The only time I straighten them now is when I break one and have to replace it. The camber is uneven if you have a new straight arm and an older bowed one. Boiling helps you straighten them after they're bowed, but I don't think it prevents them from bowing.

In general, stiffer stock arms will provide better performance. The flex and recovery of the RPM arms slows down how fast the car can react to turns and bumps. On heavier vehicles, the difference in performance is probably more obvious. So, it's a choice between performance and durability. But if you decide to stick with RPM arms, my advice is don't worry about the bowing.

 

[Velodromed]

Ha, that's nothing. You should see mine. Yes, the Typhon RPM arms bow. The Granite ones do also, but not as quickly since they're shorter. I just leave them bowed. The main difference is less ground clearance as they get more bowed. The camber also changes, but you can adjust accordingly. Bowed arms may actually keep you lower and increase handling performance, but to be honest, I don't notice much difference either way. I used to boil them and straighten them out, but the way I jump, they get bowed again in no time. The only time I straighten them now is when I break one and have to replace it. The camber is uneven if you have a new straight arm and an older bowed one. Boiling helps you straighten them after they're bowed, but I don't think it prevents them from bowing.

In general, stiffer stock arms will provide better performance. The flex and recovery of the RPM arms slows down how fast the car can react to turns and bumps. On heavier vehicles, the difference in performance is probably more obvious. So, it's a choice between performance and durability. But if you decide to stick with RPM arms, my advice is don't worry about the bowing.

Much appreciated man! That’s what I needed to understand. The short rpm arms are fine, I have them on my granite and it doesn’t bug me when they bow slightly. I was just surprised by how much and how fast the typhon ones bow. I’m kind of stuck with them because, as always with parts, I bought more than one set. I will take your advice and not worry about it. You’re also right in that I really don’t notice when I’m ripping the car around thanks buddy!

 

[WatahBoy]

I think most RPM A Arms bend. I had a bent arm on my Outcast 8S. Boiled and straightened it. It seems to be holding up so far. The 6S parts are similar but supports less weight.

 

[Monster Dork]

I put RPM arms on my Kraton 6s during COVID when I couldn't find EXB replacements. They were so soft, during my first few minutes out I bent both front CVDs like the letter "s". My bump stops were set, so it isn't that. Then I put it on the bench, where it squatted more and more under the flex. Nope, no more. I switched back to EXB arms, bought some extras when they came available, and put the RPM pasta noodles in my parts bin for someday... or never. I'm fully disappointed with RPM on the Kraton 6s. Save them for the 1/10th cars, they work better in that weight class.

 

[slick2500]

I put RPM arms on my Kraton 6s during COVID when I couldn't find EXB replacements. They were so soft, during my first few minutes out I bent both front CVDs like the letter "s". My bump stops were set, so it isn't that. Then I put it on the bench, where it squatted more and more under the flex. Nope, no more. I switched back to EXB arms, bought some extras when they came available, and put the RPM pasta noodles in my parts bin for someday... or never. I'm fully disappointed with RPM on the Kraton 6s. Save them for the 1/10th cars, they work better in that weight class.

My fronts became so twisted its not funny.

 

[Monster Dork]

My fronts became so twisted its not funny.

Mine looked precisely the same when they came off!

 

[slick2500]

Mine looked precisely the same when they came off!

The stocks ones are fairly twisted as well. I'll snap some pics when I find them.

 

[Velodromed]

The RPM arms are holding fine so far, probably because they’re still new. The most irritating thing is can’t set droop on the rear because the arms do not sit in the right position. The droop screw is offset from the tab on the chassis. I know now after the fact that these are arms are meant for the V4 and I have a v5. Oh well.

I’ll go back to stock when these need to be switched out. Meanwhile I will try to break them.

 

[joshludden]

The RPM arms are holding fine so far, probably because they’re still new. The most irritating thing is can’t set droop on the rear because the arms do not sit in the right position. The droop screw is offset from the tab on the chassis. I know now after the fact that these are arms are meant for the V4 and I have a v5. Oh well.

I’ll go back to stock when these need to be switched out. Meanwhile I will try to break them.

How long do you guys boil these parts? Do "shock " em in cold water afterwards?