Rebuilt Gen 1 Trans and new torque converter by Circle D. Getting a weird grinding noise in 4th gear at 1,200 rpms.

[Andrrw]

Rebuilt transmission and new torque converter from Circle D. I am now getting a metal scraping noise/grinding at 1,200 rpms in 4th gear. It’s loud and annoying. I have checked the heat shields multiple times and the IWE system (all new and holds vacuum at hubs and lines). If I give it a bit of gas and go above 1,500 it goes away. If I down **** it goes away. Here is the real weird thing. If I shift Into 4H it instantly goes away and I can’t replicate it once in 4H. To me it seems like the transfer case but I’m so sick of replacing parts on this. 2010 W/Whipple stage 2 w JDM Tune. Replaced basically every moving part in the drivetrain besides the transfer case. High performance drive shaft, rear end pinion bearing, axle bearings, cv shafts, all new. Truck has 79K. Any suggestions appreciated! Dealer thinks transfer case.

 

[CoronaRaptor]

I have no idea, but the good thing is a transfer case is easy to replace, not a lot of labor involved. I know money is never endless, but I've never had a problem with changing parts on an "older" vehicle, just don't like chasing parts to replace. Good luck, sounds like your truck is almost new again!

 

[Dane]

4H not causing it is SUPER suspicious. It can still be IWE - just not vacuum related. Have you checked your axle nuts? A loose axle nut will cause this. Did you replace your IWEs with all of the other stuff listed above?

 

[FordTechOne]

Although the IWEs hold vacuum, that doesn’t mean they’re receiving sufficient vacuum from the engine. At low RPM in higher gears engine vacuum will be low, especially with a supercharger. You may want to disconnect vacuum from the IWEs to fully engage them and then re-evaluate.

 

[Dane]

Although the IWEs hold vacuum, that doesn’t mean they’re receiving sufficient vacuum from the engine. At low RPM in higher gears engine vacuum will be low, especially with a supercharger. You may want to disconnect vacuum from the IWEs to fully engage them and then re-evaluate.

I actually rigged up a boost gauge (that also shows vacuum) connected to my IWE line to monitor that vacuum since this has been an issue in the past. Of course now that I have that gauge, as well as a new set of silicone lines ready to go in, I haven't had any vacuum loss or IWE issue. So in short, have the parts ready and you'll never need them - story of my life.

I think this troubleshooting idea is great since it lets you remove the t-case from the equation if the problem goes away in 2WD with the IWEs engaged - which I think it will.

 

[Andrrw]

Thanks for the reply’s. I have disconnected the vacuum line so the IWE’s stay engaged but the transfer case is not. Noise still present. Yes I did replace the IWE’s as well. I took the truck into the Ford dealership today and rode with the tech. They treat me like gold up there. It may be that I spent over $25K with them in the last two years. The tech got the truck in the air and had their transmission tech listen to the transmission while it was in gear and wheels moving. The transmission tech instantly heard the transmission making noise. He was confident it was the transmission. By the time I stepped under the truck the noise was gone. He swears it’s bearings in the transmission making noise. I’m not sure Circle D replaced all of the bearings with the build. I am going to a transmission shop tomorrow. I don’t want to give up on it. I am too deep. The tech also told me that my transfer case had less than a quarter quart of fluid in it when he checked. He filled it but still have the noises. I will report my findings. Problem is Circle D stands behind their products but not labor for removal and install or shipping. That’s about $3K.

Circle D also wants me to monitor when the torque converter locks up. I am going to see if my data log program can monitor this. See if there is a correlation.

I have not checked the axle nuts but I will ask the mechanic that did the work. We are both confident the noise is nit from the IWE’s. I have heard that noise and this is different.

 

[WHBD]

Update on this?

 

[Andrrw]

Update on this?

Turns out the tune from JDM engages the torque converter very quickly which puts a lot of load on the drive train. Kind of like having a stick shift and putting it in fourth gear at 25 mph and letting the clutch engage right away. The motor has a bogged down feeling because the clutch is fully engaged just like the torque converter is now fully engaged. A stock converter doesn’t do this because the way it is designed. This is actually very good for performance and keeping the transmission and torque converter together. Just lacks perfectly smooth operation at low rpm’s. I feel like I have learned so much about this truck. Once you start going down a “racing” path some things are given up to get better performance. Also both of my Catalytic converters internals were crumbled to pieces so that made a bunch of noise under load. 80K now with the SC so I expected the cats to be smoked.

 

[CoronaRaptor]

So, the noise is all gone, was just a shudder you think?

 

[MTF]

I forgot all your mods, are you running headers and what cats are they?