Blown up transmission, Rebuild options?

[settlingabyss12]

No blown-up transmission thread, but posting this to help others if they have similar modifications as I do.

2016 Fiesta ST, the first owner
83,593 miles
failure: 5th gear sent to the moon; I have yet to pull the transmission, though. The car will stall in neutral while letting out the clutch; I can hear clunking (perhaps the shaft snapped, doesn't want to roll in neutral either).
Mods: Spec lightweight flywheel, Spec unsprung stage 5 clutch (sintered Iron), M-sport R2 axles, Wavetrac LSD, New Transmission bearings, G25-550 (~was around 400hp), 4-port Aux Fuel, 225/45/r17 Federal RSRR's and a ton of other irrelevant modifications.

The car has an ign cut FFS setup (cobb fuel cut FFS wasn't able to slow the rpms down enough), blew up while flat foot shifting from 4th to 5th on the highway near 100 mph. I started with a pull from 2nd gear, and I flat foot shifted every gear change from there to where it blew up (5th gear). The Transmission was torn down, and all bearings were replaced about 20k miles ago at ~60,000k miles. Didn't replace any gears, as they all looked fine, and it has survived 20k hard miles since the rebuild (probably had some cracks I couldn't see). The big turbo setup was installed around 5k miles ago, at 77k miles. Unsprung clutch and LWFW have been on the car for 40k miles, and I replaced the disc and friction surface simultaneously as the transmission was overhauled.

Not sure what direction to take the car next. I think if I buy another factory transmission, it will likely suffer the same fate. There don't seem to be any companies that offer aftermarket gear sets, and the companies that offer rebuilds probably aren't that much stronger of a transmission. Looking into swapping to the Fiesta R2 transmission because it is much easier to rebuild (splined gears instead of press-fit) and utilizes straight-cut gears, which are easier to design stronger. The data I've found on it claims that it's rated for up to 1000nm to torque, which is far more than I need for this car. Did anyone swap the Sadev R2 transmission into their Fiesta ST yet? At ~$5,500 for a brand new box, it seems pretty reasonable. I was able to find some used spares around the $2.5k-3k range, will need the tarmac gear ratios because the gravel ones seem way too short for the street.

Any info is appreciated!

 

[shouldbeasy]

https://www.pandamotorworks.com/products/clarke-transmission-fiesta-st

 

[settlingabyss12]

https://www.pandamotorworks.com/products/clarke-transmission-fiesta-st

I don't think they are replacing any of the gears or upgrading the shafts, just a rebuild with improved bearings and an LSD, unfortunately. For that price, I think it's a better deal to go with the Sadev box because it's sequential and straight cut.

 

[M-Sport fan]

IF you are OK with the straight cut SCREAM on the street, and the crazy frequent rebuilds required (even though you are not using it quite as harshly as the rally pilots are on the stages, but, you are putting almost TWICE the power through it as any of the R2 cars do), I say go for it!

I'm pretty sure that the R2 kit comes with it's own throttle/spark cut potentiometer on it's massive shifter, etc., But I am not positive whether or not that system requires the M-Sport stand alone ECM, or can be interfaced with ours.

Is the reverse backup light switch the only 'sensor' on our B6 gearboxes?

 

[jeffreylyon]

I tried driving a non-sequential, straight-cut, dog box on the street long ago. Not for me; way too serious all the time.

I've read that an unsprung clutch with a non-dual-mass flywheel causes much more stress on the gearbox. And, with the power that you're putting down and the traction that you've got, you may be looking at the gear box as a wear item. For sure, the Sadev is going to require way more maintenance and cost way more than a freshened stock box.

 

[M-Sport fan]

The Sadev does come standard with a 3 different 'ramp' rate adjustable, clutch plate type limited slip, which I am guessing they themselves manufacture.

 

[TyphoonFiST]

The Sadev does come standard with a 3 different 'ramp' rate adjustable, clutch plate type limited slip, which I am guessing they themselves manufacture.

How much again?

 

[TyphoonFiST]

The Sadev does come standard with a 3 different 'ramp' rate adjustable, clutch plate type limited slip, which I am guessing they themselves manufacture.

This it.....maybe?

https://www.sadev-tm.com/en/product...l-drive-transverse/29-st82-14-transverse.html

 

[M-Sport fan]

Similar, but these are 5 speed, and never use paddle shifters which are verboten in R2 rally competition.

 

[TyphoonFiST]

Similar, but these are 5 speed, and never use paddle shifters which are verboten in R2 rally competition.

Says its 6 speed with 1 reverse* for 1.6Lengines

 

[settlingabyss12]

IF you are OK with the straight cut SCREAM on the street, and the crazy frequent rebuilds required (even though you are not using it quite as harshly as the rally pilots are on the stages, but, you are putting almost TWICE the power through it as any of the R2 cars do), I say go for it!

Is the reverse backup light switch the only 'sensor' on our B6 gearboxes?

This car is a fun car that I am learning to modify cars on, and I like the idea of making it as crazy as possible. I have other cars that are fast and comfortable; I don't have any crazy all-out cars. As for the frequent build, I don't mind doing that on this gearbox because it's designed in a way to be easily rebuildable.

Here is one for sale for $3300; that's way less than I paid for just my turbo kit, and it's freshly rebuilt too!
http://www.racepartstrader.com/listing/fiesta-r2-sadev-sequential-gearbox/

I have contacted M-Sport about pricing and ordering custom ratios, so I have something better tailored to the street. The Sadev R2 transmission is a 5spd with 1 reverse gear. It wouldn't be hard to
integrate an aftermarket throttle cut/spark cut potentiometer.

If this doesn't end up working out, I will probably swap drivetrain setups and go AWD. It's a big project, and I've never modified anything that extensively, so id rather see if I can get this to work first. I've also attached some really cool documents relating to the R2 transmission.

 

[settlingabyss12]

I found a better Sadev R2 Technical Details PDF. You can clearly see everything much better in this pdf.

 

[settlingabyss12]

Beautiful, freshly rebuilt.

 

[JDG]

I take it this is not a daily driver? How much horsepower are you making? I suspect the lightweight flywheel may be the culprit. The dual mass flywheel will dampen the forces during shifts so the gears don't see a huge shock. A less agressive clutch may help with this too. I'd be interested to see how modified you are.

 

[settlingabyss12]

I take it this is not a daily driver? How much horsepower are you making? I suspect the lightweight flywheel may be the culprit. The dual mass flywheel will dampen the forces during shifts so the gears don't see a huge shock. A less aggressive clutch may help with this too. I'd be interested to see how modified you are.

Nope, not a daily driver at all.
Probably in the 400hp-430hp range.

I agree for sure. I think in most cases though, the stock clutch or a less aggressive clutch will eat most of the shock, even with the lightweight flywheel. In my situation though, my clutch has a much higher coefficient of friction; it's rigid (unsprung), and finally, I have a lightweight flywheel which is also unsprung.

To continue, I also have flat foot shifting setup with Ign cut (instead of fuel cut). During the shifts, the car actually holds a few psi of boost pressure, and the turbo I have spools very quickly. I absolutely loved the setup; it was extremely satisfying to drive, and the shifts were amazing, but it was at the cost of my transmission.

I really want to work on this car myself, mainly because I like learning new things and taking on difficult challenges. I'm not comfortable yet doing a drivetrain swap to all-wheel drive, so I think the R2 transmission would be a great route (bolts up without fabrication). The power dropped down into the 350-370 range and the sequential transmission will be a very fun combination.

 

[M-Sport fan]

But still, you do NOT ever want to get stuck in any stop and go traffic with a Sadev, and an 'on-off switch' clutch, even if that is a lot less likely with a weekend/track car..

 

[JDG]

I take it this is not a daily driver? How much horsepower are you making? I suspect the lightweight flywheel may be the culprit. The dual mass flywheel will dampen the forces during shifts so the gears don't see a huge shock. A less agressive clutch may help with this too. I'd be interested to see how modified you are.

Guess I jinxed myself posting in this thread. But just had a similar failure in my transmission at 85,500 miles. During a downshift to 5th from 6th getting ready for a pass on the highway while just cruising at 65mph, heard all kinds of noises and 5th gear was like neutral. 5th and 6th are now neutral while 1-4 work but make terrible noises. Luckily I have a spare but it is not ready to go yet so not sure when I will get the car going again.

 

[MagnetiseST]

Guess I jinxed myself posting in this thread. But just had a similar failure in my transmission at 85,500 miles. During a downshift to 5th from 6th getting ready for a pass on the highway while just cruising at 65mph, heard all kinds of noises and 5th gear was like neutral. 5th and 6th are now neutral while 1-4 work but make terrible noises. Luckily I have a spare but it is not ready to go yet so not sure when I will get the car going again.

Id be surprised if it isn't the input shaft, they tend to snap.

 

[Sam4]

I'm at 78K and waiting for the tranny to grenade. Ford replaced the input shaft bearings at 59.9K - they were pissed! Now I've lost downshifting into 5th (upshift is fine), and 3rd wants to join the fun. I guess if I'm going to keep this I'll get a $4k panda-built tranny.
On another note - exhaust system is all kinds of noisy - is the front flex pipe the culprit?

 

[MagnetiseST]

On another note - exhaust system is all kinds of noisy - is the front flex pipe the culprit?

The third time we changed the transmission, it was making a whining / broken exhaust sound. It could be the transmission, not the exhaust lol