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Broke the TH350 at the track...UPDATE: it wasn't the TH350. Torque arm mount broke.
First pass this season. Had the 2 step set to 3K, builds about 2 psi on the brake. I was hoping to gauge the track conditions and then adjust as needed. Not having a cage, I can only run the 8th so I let off. approx. mid track. I really should have cleaned the M/T DR a bit more but I guess better traction would have meant I would've killed the TH350 on the first pass rather than the next.
The next pass attempt, the tires were warmed up better but when I let go of the transbrake, it got about 10 feet off the line when it sounded like somebody was beating the tranny with a ball peen hammer. I let off immediately and got off on the shoulder to inspect. The trans was sounding like a box of rocks being rolled around. There was a few drips of trans fluid dripping, not a lot. I was able to back off the track and then get to an area where a wrecker could pick up the car. She's home now and I'm putting in the 4L80E I bought a month or so ago. I'd planned to install it this winter but its going in now
Last edited by mightyquickz28; 07-19-2018 at 03:58 PM.
Update: Just went out to pull the TH350. Got her up in the air, got the air wrench out to take off the torque arm. Looked up and, I'll be damned. It wasn't the TH350 that let go, the torque arm mounts on the Hybrid 8.8 broke off. I'd been needing to replace the 28 spline rear end, in use since 2003, with some 31 spline or better iterations. So the 4L80E install can be put off for awhile. I already bought a rebuild kit, some heavy other components, 1350 Yoke, Hughes SFI approved Flexplate and a tool to hang the trans while building it. I saw an online place selling pre-built 8.8's so I'll go check them out.
Update: Just went out to pull the TH350. Got her up in the air, got the air wrench out to take off the torque arm. Looked up and, I'll be damned. It wasn't the TH350 that let go, the torque arm mounts on the Hybrid 8.8 broke off. I'd been needing to replace the 28 spline rear end, in use since 2003, with some 31 spline or better iterations. So the 4L80E install can be put off for awhile. I already bought a rebuild kit, some heavy other components, 1350 Yoke, Hughes SFI approved Flexplate and a tool to hang the trans while building it. I saw an online place selling pre-built 8.8's so I'll go check them out.
That's music to my ears brother! I too have a th350 behind my boosted 6.0, I rebuilt it myself using only stock components so I don't have much faith it'll last. Been good for a year but haven't dead hooked it yet.
Yes. My hybrid 8.8 was one of the first batch back in 2003 from a gent that started a short lived business of taking Explorer 8.8 center sections, welding on *your* GM 7.5" 10 legs. I've ran it over the years with slicks, several pairs of Nittos, using Nitrous and Turbo charged engines. The Transbrake'd 'leaves' must've been too much. The original guy (Chad?) had a business called 'Extreme Chassis'. He was only in business for a short time. I found out by recommending his work to another Fbud and that guy said, "Extreme Chassis is out of business. Seems like some his customers rear ends broke the torque arm mounts when they had high powered cars with slicks". I grimaced a bit at the time, wondering if mine was immune or just a matter of time. Mystery solved, lol....
I just ordered a new 8.8 with 33 spline axles, 3.55 gears, TruTrac. Just under 3K delivered. Completely assembled. Ready to add gear oil and then start driving. Only bad thing is that it will take 4 to 5 weeks to get put together and delivered. Oh well, a BIG plus is now, I wont be afraid to use my slicks! My old 8.8 only had 28 spline Strange axles, so drag radials were my only option for fear of snapping an axle.
Originally Posted by merim123
So the welded part added to the 8.8 to support a tq arm broke?
I'll have some tomorrow. Heading over there early in the morning to do some things to it.
Looking at the way that my new 8.8 has been done, it looks stout. I think I'd seen a thread about some guys making a similar 'box' for the 8.8 torque arm mount. You just had to weld it on.
My 2003 unit... hmmm.. I think I have a picture of it somewhere or a link even in ls1tech.com for it. Let me look...
Awesome that you do them for friends, etc. It's been a great unit for sure 15 years of abuse and just now breaks and it's the torque arm mount, not the gear/axles!
Originally Posted by Cwarta
Happen to have any photos? I do 8.8s for myself and my friends, I haven’t had any issues to date, I’d be interested in knowing what broke and where.
I'd be interested to see if the shock of the torque arm letting go, was enough to wreck your roller clutch. What was causing the transmission to puke a bit of fluid?
Yeah, I'm curious about that as well. I'll pull the pan to see if there's any debris in there. I've had a oil tray under the car for over a year now and never had it drip at all until this event. The driveshaft appears to be fine, though it is 'scored' where it got up against a raised bit of sheet metal where the E-Brake cable traverses from the interior to the trans/driveshaft tunnel. Just a scratch but I always wonder about stress risers. Its a Denny's nitrous ready 1350 shaft so it should be fine. I'll have some pic's tomorrow. Just couldn't get to it completely today.
Originally Posted by Game ova
I'd be interested to see if the shock of the torque arm letting go, was enough to wreck your roller clutch. What was causing the transmission to puke a bit of fluid?
Got the 8.8 out all the way. Yuck. So, based on the rust on the top 'support'/brace, it looks like it had actually broke/parted some time back. I NEVER drive this car in the rain and it hasn't been thru a drive-thru car wash in years(I always hand wash the car). So that left only the side weld to the housing and the bottom support to take the brunt of the launches. Looking at the inner tubes for the torque arm bolts, they look thin, abused, distorted and cracked. I'm glad this thing let go at the launch and not on the big end of the track. Could have been messy...
Look at the rust on the top support/brace. Looks to have been apart for some time.
It’s not cast iron, and it looks to me that the steel tube broke that he used for the mount and the the little sections of the other welds weren’t big enough to hold, that would have happened just the same on a steel housing imo.
Either way, the Hiltsy mount this would have never happened
Hiltsy looks far sturdier and does completely encapsulate which should be big time better than this. Impressive this held up all these years. Who is the new one from?
Hiltsy looks far sturdier and does completely encapsulate which should be big time better than this. Impressive this held up all these years. Who is the new one from?
Yes. I admit, when it first arrived on the pallet back in 2003, I looked at it and thought, "hmmm... That looks....well... not strong". Back then, I was running a 100 shot of Nitrous on an LT1 having CC 224/236 cam, headers and ported stock castings. But I ran Nittos all the time and ET streets at the strip. It took it all without failure. But that top support being so aggressively rusted, dang.... This sure tells me I need to inspect far more frequently than I do. I'm routinely under the car just puttering around but I hadn't been looking for this kind of compromised parts. I'll be more diligent in the future.
Originally Posted by MY_2K_Z
Wow that's a pretty shitty design. I'm surprised it lasted that long.
07-13-2018, 10:34 AM
Broke the TH350 at the track...UPDATE: it wasn't the TH350. Torque arm mount broke. 
