Are EXOTEK diff cups worth it?

[Spence]

HI guys, after some further reading on these forums, the stock diff cup screws look like garbage, they are a self tapping screw. I just read on these forums that the screws can snap and blow diff gears, as well as ring and pinion gears.

I mean my plan would be out of the box rtr, to replace the servo and servo horn, as well as installing a castle waterproof bec. Would start to run it with a 2s lipo pack.
I'm just not sure if its an immediate thing to replace the diff cups or not...

I was thinking of doing rear, and center diff upgrades with the exotek cups..


Granted I can't purchase the rock rey currently, but this time is perfect to do research before I buy or have upgrade plans.

I'm curious if this is simple as just replacing the diff screws with a regular m3 metric counter sunk bolt of the same diameter and length? Or if its worth it to get the EXOTEK diff cups.


I don't really like the exotek diff cups cause it appears that the bearing surface is aluminum as opposed to a steel bush. I'm just curious how you guys have faired with the exotek cups.


I have also seen the upgraded front driveshafts too, just a beautiful aluminum piece that bolts onto the stock outdrives, of course out of stock lol.. They should have made them from steel lol... Still look really nice and worth a buy...


Thanks
-Spence

 

[mass-hole]

Look up the traxxas screw mod. I believe it is essentially what you are talking about, upgraded bolts.

My exoteks(front and rear diff) have held up great so far.

 

[Spence]

Cool thanks

 

[willyg1981]

Hi Spense,

It all depends what you are planning to do with it really ,...they can last for a fair while if you nanny it , but let’s be fair who wants to do that [emoji848].....

You might go out thinking ok I’m not going to gun it and then you get carried away and before you know they’ve snapped ,..for me it happened pretty quickly
Others were luckier than me lol .

If I was to buy one now after doing the research and add up the cost of 3 replacement diff cup kits it’s not far off 100£ with postage and then the cost of the upgrade screws it’s a no brainer really ,

As for the aluminium cups there’s a bit of a advantage as the inner walls of the cups won’t degrade as quick as the plastic ones will ,...but if your using a locker then the diff gears won’t be rubbing the inside so that’s irrelevant.

I would say for the front it’s a good idea but rear and centre , not necessary if your using the locker , which nearly everybody does ,

The main upgrades I found most beneficial was (1) diff screw upgrade , (2) 3rd member , (4) good set of bearings , (5) front bulkhead , (6) bell crank steering (7) good quality servo using hard wired bec (8) proline xt’s rear springs accompanied by the extra proline spring pack to tune them in 37.5 wt in rear and 33wt in front .

The other thing to bear in mind in the stock diff cup washers found at either end , I found them
to distort into a bowl shape causing the gear to slip even more resulting in a very slippy diff almost useless , replace these when the diff gears are being used but again if your using a locker it’s not necessary .

The installation of the upgrade screws is not that straight forward , the holes in the ring gear need to be enlarged enough for the wider screw shank to clear , using a grinding bit I found most successful,
Then the screw holes in the cups need to be enlarged and tapped to take the engineering screw thread , if you don’t you will have bulges in the outside of the plastic cup wall and these bulges will catch of the pinion gear as it rotates . It’s not a huge problem but it annoyed me to no end .

Hope you find this helpful [emoji106]


Sent from my iPhone using Tapatalk

 

[Spence]

Hi Spense,

It all depends what you are planning to do with it really ,...they can last for a fair while if you nanny it , but let’s be fair who wants to do that [emoji848].....

You might go out thinking ok I’m not going to gun it and then you get carried away and before you know they’ve snapped ,..for me it happened pretty quickly
Others were luckier than me lol .

If I was to buy one now after doing the research and add up the cost of 3 replacement diff cup kits it’s not far off 100£ with postage and then the cost of the upgrade screws it’s a no brainer really ,

As for the aluminium cups there’s a bit of a advantage as the inner walls of the cups won’t degrade as quick as the plastic ones will ,...but if your using a locker then the diff gears won’t be rubbing the inside so that’s irrelevant.

I would say for the front it’s a good idea but rear and centre , not necessary if your using the locker , which nearly everybody does ,

The main upgrades I found most beneficial was (1) diff screw upgrade , (2) 3rd member , (4) good set of bearings , (5) front bulkhead , (6) bell crank steering (7) good quality servo using hard wired bec (8) proline xt’s rear springs accompanied by the extra proline spring pack to tune them in 37.5 wt in rear and 33wt in front .

The other thing to bear in mind in the stock diff cup washers found at either end , I found them
to distort into a bowl shape causing the gear to slip even more resulting in a very slippy diff almost useless , replace these when the diff gears are being used but again if your using a locker it’s not necessary .

The installation of the upgrade screws is not that straight forward , the holes in the ring gear need to be enlarged enough for the wider screw shank to clear , using a grinding bit I found most successful,
Then the screw holes in the cups need to be enlarged and tapped to take the engineering screw thread , if you don’t you will have bulges in the outside of the plastic cup wall and these bulges will catch of the pinion gear as it rotates . It’s not a huge problem but it annoyed me to no end .

Hope you find this helpful [emoji106]


Sent from my iPhone using Tapatalk

My big question is tho, drilling the diff ring gears for the screw mod. They're $36 a set... I just wouldn't want them to be sloppy if I were to buy the exotek diff cups. I'm not sure if I should go with the traditional m3 but stock length screws or what... Seems the exotek is an m2.5 screw, not an m3 so confusing, but .5 of a millimeter really isn't a big difference, I think the counter sunk style of the losi ring gears will make up for that... Guess I'd just use an M2.5 screw..

Geeze the losi rock rey needs so much work to be good lol I'm basically going to take it out of the box, and start on the diff mods, center locker, BEC install, upgrade servo, upgrade horn...

I'm wondering what washers I could find to replace those diff washers in the front diff...


Thanks man!

 

[willyg1981]

Enlarging the ring gear is fairly easy , just use a pointed dremell grinding stone bit and let it do it’s thing ,..the counter sunk head does the job of locating the screw to the cup ,
as for enlarging the holes it’s very easy the stock screw are 1.5 if I remember correctly ,
using a 2mm it will easily follow the threads of the self tappers and then follow up with the 2.5 tapp , all very easy as long as you take your time and at the moment this is something that most of us all have plenty of lol ,
All of these jobs were done over the course of a nearly a year as things broke and as things were released , but I’d say you’ve got a really good head start nail all of these weak links and it will put one hell of a smile on your face !

What are you going to do with it ? Bash , race ? Or eleven crawl ?

Your very welcome buddy [emoji106]


Sent from my iPhone using Tapatalk

 

[willyg1981]

These are the washers for the cups , really really solid compared to the tinfoil rubbish for the stock [emoji23]

Sent from my iPhone using Tapatalk

 

[mass-hole]

Yeah I also touched the dremel bit on each side of the ring and it was quite tight shoving the exotek diff screws through. Basically had to thread the screws through the holes they were that tight.

 

[Spence]

Enlarging the ring gear is fairly easy , just use a pointed dremell grinding stone bit and let it do it’s thing ,..the counter sunk head does the job of locating the screw to the cup ,
as for enlarging the holes it’s very easy the stock screw are 1.5 if I remember correctly ,
using a 2mm it will easily follow the threads of the self tappers and then follow up with the 2.5 tapp , all very easy as long as you take your time and at the moment this is something that most of us all have plenty of lol ,
All of these jobs were done over the course of a nearly a year as things broke and as things were released , but I’d say you’ve got a really good head start nail all of these weak links and it will put one hell of a smile on your face !

What are you going to do with it ? Bash , race ? Or eleven crawl ?

Your very welcome buddy [emoji106]


Sent from my iPhone using Tapatalk

Interesting, so the screws I would have used anyway are m2.5mm screws not m3 I thought they were m3 but they're m2.5 An m3 tap will not fit in a threaded hole that an m2.5mm screw will fit in lol... Kinda a relief.."thumbsup"

Thanks for the info, currently I cannot purchase the rock rey not due to lack of funds, I need to save money lol cause I got furloughed (laid off) from my job..

I plan to primarily bash a little here and there, forest hill climbs, maybe a little crawling, and some U4rc racing later... Really primarily just having fun with it in the woods...

Thanks again for your help!

 

[willyg1981]

My bad ,..these are the upgrade screws I used m2 but high tensile but any din12:9 countersunk screw will do as long as they are din 12:9 or 9:12 I can’t quite remember which way round it is lol
The m2 tapp will quite happily eat there way in there ,..

Yeah that sucks man , I’m sure it will all work out in the end ,...I’m sure you will be back employed and we will all be playing back outside with our rc’s in the not too distant future .

You’ll love it man it will excel in all those areas easily it really is a class above all the other rock racers on the market once all these issues have been addressed [emoji108]


Sent from my iPhone using Tapatalk

 

[Spence]

My bad ,..these are the upgrade screws I used m2 but high tensile but any din12:9 countersunk screw will do as long as they are din 12:9 or 9:12 I can’t quite remember which way round it is lol
The m2 tapp will quite happily eat there way in there ,..

Yeah that sucks man , I’m sure it will all work out in the end ,...I’m sure you will be back employed and we will all be playing back outside with our rc’s in the not too distant future .

You’ll love it man it will excel in all those areas easily it really is a class above all the other rock racers on the market once all these issues have been addressed [emoji108]


Sent from my iPhone using Tapatalk

One more question, I'm sorry lol, probably driving you nuts :lmao:

So those protek screws are 2mm, as well as the screws that come with the exotek? So if I want to get exotek cups I can later...

 

[willyg1981]

One more question, I'm sorry lol, probably driving you nuts :lmao:

So those protek screws are 2mm, as well as the screws that come with the exotek? So if I want to get exotek cups I can later...

Sorry buddy I fell asleep ,
Yes you can [emoji106]


Sent from my iPhone using Tapatalk

 

[willyg1981]

Dont be sorry either buddy , it’s not a problem [emoji16] happy to help [emoji106]


Sent from my iPhone using Tapatalk

 

[Spence]

Dont be sorry either buddy , it’s not a problem [emoji16] happy to help [emoji106]


Sent from my iPhone using Tapatalk

Well, thanks to a $1200 IRS tax refund, lol I got the go ahead ok from my parents to grab the rock rey and all the other bare necessary pieces to get it going, leaving the other remaining money for other actually important things lol

So to do the diff screw mod, just remove the old screws, follow up with the 2mm metric tap, as well as widening the the ring gear holes a little with a dremel tapered stone bit? I just wanted to be sure the fit between the new screws and the plastic diff cups isn't too loose

 

[willyg1981]

Woohooo , that’s awesome news good for you !!!
Do you have a cordless battery drill , using the cordless drill makes the whole tapping thing much easier ,
Set it on low speed and allow it to eat it way in ,..

If you have a scrap of plastic lying around use this to practise on , like a old plastic chopping board clamped on edge to allow the full length of drill and tapp , how it pulls it self in and how quickly the tapp flutes fills with waste material ,

When they are full reverse the tapp and clear the flutes also be mindful of the depth of the screw you are going to use .

If it does go a bit pear shaped on the diff cups use some super glue , I’m sure it’ll be fine though even without the practise [emoji106]


Sent from my iPhone using Tapatalk

 

[Panther6834]

Enjoy. You're gonna have a blast with it. I've been acquiring hop-ups for my Baja Rey, even though I can't install most of them yet (only because I don't want to disassemble/reassemble the BR multiple times). I'm working on another order, as I told this. Not sure I'll get everything else I need, or if I'll have to only order some of the remaining things. Point being, if you can afford all the upgrades you plan, best to get them all at once. That way, you'll only have to disassemble/reassemble once (not counting the usual maintenance).

~ More peace, love, laughter & kindness would make the world a MUCH better place [emoji1690]

 

[amanc96]

Enjoy. You're gonna have a blast with it. I've been acquiring hop-ups for my Baja Rey, even though I can't install most of them yet (only because I don't want to disassemble/reassemble the BR multiple times). I'm working on another order, as I told this. Not sure I'll get everything else I need, or if I'll have to only order some of the remaining things. Point being, if you can afford all the upgrades you plan, best to get them all at once. That way, you'll only have to disassemble/reassemble once (not counting the usual maintenance).

~ More peace, love, laughter & kindness would make the world a MUCH better place [emoji1690]

I'm in the same boat. I bought my RR a month and a half ago and just did a quick test run to make sure everything worked. I've been picking up a few parts here and there and just going to do everything all at once.
All the screws you have to undo just to get the cage off is kind of annoying...

 

[amanc96]

Well, thanks to a $1200 IRS tax refund, lol I got the go ahead ok from my parents to grab the rock rey and all the other bare necessary pieces to get it going, leaving the other remaining money for other actually important things lol

So to do the diff screw mod, just remove the old screws, follow up with the 2mm metric tap, as well as widening the the ring gear holes a little with a dremel tapered stone bit? I just wanted to be sure the fit between the new screws and the plastic diff cups isn't too loose

Congratulations! Let the fun begin! :ror:

 

[Panther6834]

I'm in the same boat. I bought my RR a month and a half ago and just did a quick test run to make sure everything worked. I've been picking up a few parts here and there and just going to do everything all at once.

All the screws you have to undo just to get the cage off is kind of annoying...

For those work the standard BR, they only have 12 screws to remove. For those of user with the Raptor brains, we have more than double that...but, there is a 'solution'. The primary reason for so many screws is because of the light bars. If you add a (somewhat) lengthy servo extension, then you can remove the cage (with lighting attached) using the same 12-screw method those with the 'standard' BR get to enjoy. Instead of buying two lengthy extension, you actually only need to buy one - a 200-300mm Y-extension should not only be long enough, but will allow you to power both LEDs from a single Rx channel. Mine should be arriving in 2-3 days.

Speaking of upgrades, for several more ordered today: HR aluminum rear shock tower, 3 Exotek differential gear cases, Exotek HD carbon fiber top plate, SSD aluminum front bulkhead, Exotek aluminum HD steering set (ie. servo saver), Losi aluminum upper/lower rear bulkhead track rod mount set, Losi aluminum servo mount, & Incision rear upper links. However, I still haven't gotten those darn bearings ordered. Honestly, that was on purpose, as I want to verify the sizes needed for the parts I ordered today. There are still other parts needing to be ordered, but today's order contains the last of the upgrade parts using bearings. Once received, I can finally order the bearings...just need to decide which Avid bearings to go with.

~ More peace, love, laughter & kindness would make the world a MUCH better place [emoji1690]

 

[amanc96]

For those work the standard BR, they only have 12 screws to remove. For those of user with the Raptor brains, we have more than double that...but, there is a 'solution'. The primary reason for so many screws is because of the light bars. If you add a (somewhat) lengthy servo extension, then you can remove the cage (with lighting attached) using the same 12-screw method those with the 'standard' BR get to enjoy. Instead of buying two lengthy extension, you actually only need to buy one - a 200-300mm Y-extension should not only be long enough, but will allow you to power both LEDs from a single Rx channel. Mine should be arriving in 2-3 days.

Speaking of upgrades, for several more ordered today: HR aluminum rear shock tower, 3 Exotek differential gear cases, Exotek HD carbon fiber top plate, SSD aluminum front bulkhead, Exotek aluminum HD steering set (ie. servo saver), Losi aluminum upper/lower rear bulkhead track rod mount set, Losi aluminum servo mount, & Incision rear upper links. However, I still haven't gotten those darn bearings ordered. Honestly, that was on purpose, as I want to verify the sizes needed for the parts I ordered today. There are still other parts needing to be ordered, but today's order contains the last of the upgrade parts using bearings. Once received, I can finally order the bearings...just need to decide which Avid bearings to go with.

~ More peace, love, laughter & kindness would make the world a MUCH better place [emoji1690]

So are the stock bearings pretty bad? I thought about picking up the fast eddy bearing set but was going to just wait it out.