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Drive Shaft Flex Discs

61K views 220 replies 55 participants last post by  Duro5341 
#1 ·
Good news...

Found that my flex discs (sometimes called Guibos) on the end of my propeller (drive) shaft are cracking and it is time to replace them. This is good in that I caught it before a major failure.

Bad news...

Hyundai, unlike Mercedes, BMW, etc., does not sell these wear item flex discs on there own. You must buy the entire propeller shaft to the tune of $800-$1200 depending on where you go to get it.

Perfect...thanks Hyundai...

Trying to see if I can find one from another platform that is the same size to use or if there is a company that makes these that I can contact about getting into our market to make them for the Gen Coupe.
 
#2 ·
Looks like our best bet is to find flex discs off a low mileage totaled donor car.
 
#5 ·
Usually it is a visual inspection during other routine maintenance once you pass 60k (or the equivalent KMs) every oil change while the car is on the lift/jack stands. You will easily start seeing the cracks when they begin to wear out.

You may also notice more vibration from the drive train right under your seat as well as klunks when pulling away from a stop of engine braking (if you have M/T for the second one).

I found out by visual inspection when I had the driveshaft out while putting in the new clutch because Terrance pointed it out.
 
#4 ·
Wow, they really don't sell them separately. Just checked

Ever thought about getting a solid aluminum puck made?

Or even a custom shaft?

I understand that you don't want to spend all the money, but averaging $1000 for oem, you can get a decent custom one.
 
#6 ·
There is already one piece Aluminum and Carbon shafts out there. Also, I can get the OEM new for $700ish. I don't want to go Aluminum flex disc even though I know some companies that could make a custom one just because it doesn't provide the sane flex and on modded cars could lead to premature failure of other parts.
 
#7 ·
Did the '13s replace these with actual U-joints? If so would it be possible to upgrade to these parts?
 
#9 ·
No, the 13s use flex discs still. Confirmed by Snoopy.
 
#11 ·
Interesting. Thanks for the heads up. I will look into that.
 
#13 ·
You could do that anf there are already companies that do, but the driveshaft is fine. Just need the flex couplers. Its the difference between a $200 fix versus a $800-$1000 fix. I am on a budget right now and don't have that kind of money.
 
#14 ·
Since I barely ever contribute:
 
#15 ·
Nice! I am not a fan of the Revshift all aluminum flex disc myself, but if you could find out what BMW that size fits model wise, we could order and use the BMW OEM ones. Can you please clarify what model BMW that size is for please?
 
#16 ·
From revshift site...

This is the 105mm flex disc with 12mm bolt holes. It is commonly found on 2006 and newer vehicles. Please refer to the cross reference links below.

The Revshift high performance flex disc is CNC machined from 6061 billet aluminum. It utilizes high quality polyurethane bushings to maximize rigidity and strength while maintaining the proper amount of flex to protect your drivetrain.

This is a high performance alternative to the oem flex disc. The oem rubber flex disc is known for failing under high loads and needing to be replaced on a regular basis. There is no longer a need to worry after you install a Revshift flex disc on your BMW.

- CNC machined 6061 aluminum body
- 95A durometer polyurethane bushings
- Replacement for OEM part # 26117546425 (LK=105mm/12mm)
- Rebuildable using one of our flex disc rebuild kits

Installation Instructions

Product Code: FLX-10512V
 
#17 ·
Yeah, I didn't see the url links originally nor the reference to the BMW OEM part number. I am going to buy one of the BMW OEM ones to check size and fit and will report back.
 
#18 ·
One of my clients had his one cracked too, and he took the measurements to get one, and well, this is their reply.
 
#19 ·
FYI to all, I will also take the opportunity to post this as a DIY too. Flex discs aren't hard to begin with, but it is always nice to have something to reference.
 
#20 ·
Okay... now I'm subb'd. I want to grow up to be just like WildBill so when I have 200,000 miles I will still be driving my coupe. Yanno... unlike most of our mods on here.

:gc-wmscared0016:
 
#21 ·
First point of note. The BMW part number previous mentioned by Revshift is outdated. The one that is current and superseded it was 26117610061. Most of these show going for $100-$150 per flex coupler.
 
#22 ·
Interesting.

I have a CF drive shaft and it came with solid couplers. Might be why I'm starting to get a low groan at speed from the rear end. Wonder if they put too much stress on the dif.

Either way, I have a set of oem flex disks from my prop shaft if you wanna buy em. I might look into swapping to that BMW aluminum flex coupler though. If it fits.
 
#23 ·
It's possible. The Revshift flex coupler may have a bit more play than a solid one. I don't plan to get theirs, so if you are wanting to order a set and try them, I am sure others would appreciate the feedback.

As for buying your OEMs, no thanks for now. I will look into this BMW option and follow through to see if it is a viable option for the Gen Coupe community.
 
#24 ·
how isn't the drive shaft covered by the 100kmile warranty on "drivetrain" components?
 
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#25 ·
Drive shaft is, but the flex couplers are rubber wear items. Similar type situation as a clutch in a M/T car. The trans is covered, but usually the clutch is something the owner has to replace once worn. The problem with this, however, in Hyundai's case is that they don't sell them separately so you could argue that they fall under the part number for the propeller shaft and therefore would completely be covered under the warranty. Indeed, many have and have gotten this part replaced under warranty.

That being said, some people like myself are past our warranty (I am at 134K miles) and others are starting to be 2nd and 3rd owners that have a less warranty coverage term and or bought the car as-is that aren't covered either. This will only increase with time as the cars age. Given that the flex coupler is a wear part, finding a solution now helps to benefit those who will come after me to know hopefully a great alternative to this issue that isn't an arm and a leg.
 
#27 ·
Kinda wish I had $260, I'd be willing to test those BMW Revshift ones.

Also, I've still got warranty but not for much longer because in Canada we only get 5 years, but I could only imagine me trying to get a warranty approval for these couplers.
 
#28 ·
Another development:

So, the original BMW part number 26117546425 corresponds to a flex disc made by the German company Lemfoerder and corresponds to their ODM part number 3346901. This BMW part was then superseded as mentioned above to BMW part number 26117610061. This shows to be because they no longer used Lemfoerder as the ODM to make this part. Instead, they went to what appears to be Febi Bilstein to corresponding ODM part number 26294.
 
#30 ·
Wow... that is hurtful and insensitive. I would cry, but I already shed my last tear earlier.
 
#32 ·
lmao.

Anyways. I would be worried about balancing issues, if you go about replacing it yourself.

Probably why they don't sell them separately, and my intuition why some of us have had propeller shaft balancing issues.

I haven't had any balancing issues until just last summer, and I've had my car since 09
 
#33 ·
What do you mean?
 
#36 ·
A big rubber disk spinning on the end of a long pole. It doesn't take much weight to create an oscillation under those conditions.
 
#38 ·
True but if you have one on either side I would think they would help to offset each other.
 
#39 ·
Or create a double oscillation which would be even worse than if it was unbalanced on just one side. On helicopter driveshafts the adapter plate and the drive shaft is balanced as an assembly just for that reason. The tolerances are so slim that if you accidently remove the adapter from the shaft, you have to send the entire assembly back to the manufacturer to be rebalanced... even if you assemble it back the same way.

All that said, I'm sure there are plenty of places in Houston that can balance a drive shaft with the adapters.
 
#40 ·
Didn't think of it that way and your right. Will keep that in mind.
 
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