- Dec 26, 2022
- First Name
- Bob
- Last Name
- Worley
- Spouse
- Anneliese
- City
- Midlothian
- Chapter
- Dallas / Ft. Worth
- Admin
- #1
So we finished our cobra about March 2019 - titled and registered. Now have 14,000+ miles on the odometer.
For our Hurricane Cobra build I selected the Tremec TKO600 close-ratio gearbox with the 0.82 5th gear ratio, and Tilton internal hydraulic throw out bearing. It was fine initially, although I regret that 5th gear choice when we are doing 80mph freeway driving (more on that later).
After a year or so, I noticed it was getting difficult to shift back into first gear after coming to a stop. Then it continued getting worse and worse. The only resolution I had was to keep my foot on the clutch pedal and the car in gear while stopped at traffic lights or stop signs. It finally reached a point where it was difficult to shift into any gear once stopped. Something had to be done. I wasn't sure it if was a problem with the gearbox, the clutch/pressure plate, the internal HTOB, the clutch master cylinder size? Nothing I did seemed to resolve it. I gave it over to the experts, made an appointment with Grubbs Motorsports in Garland, Texas. They have painted, upgraded, repaired many mustangs, cobras, GT40s, even a few real, original 289 and 427 cobras.
Since Grubbs would pull the gearbox anyway, I decided to switch to a new gearbox. A fellow club member had a TKO-600 with the standard 0.64" 5th gear, that was almost new. I bought it, and took it to Texas Drivetrain Performance in Hurst, Texas for clean up and upgrades. They did bronze fork pad kit, carbon synchronizer kit, 2-3 shift rail modification, new front bearing retainer, new input and output shaft seals. He said it looked really new and clean inside before they started.
In the interim i had an opportunity to take the cobra to a track day at Motorsport Ranch in Cresson, Texas on November 29, 2023. I figured, why not? since I'm getting it serviced in a few weeks anyway. I ran four 30-minute sessions, and had a blast, the cobra drove better than expected, so much power! Other than down-shifting, especially 3rd-2nd so I as having to brake early, shift easy. Afterward I noticed a significant oil leak, dripping off the QuickTime bell housing. it had been dripping a bit prior to that date, but now it was a big puddle, very significant. I surmised the rear main seal had blown out. So I asked Grubbs Motorsports to also check that while they had the gear box out.
I delivered the cobra to Grubbs motorsports on Wednesday last week, after getting the replacement TKO-600 (with .64 5th gear) rebuilt at Texas Drivetrain Performance.
At Grubbs, they found the Tilton TOB was right against the clutch fork, and surmised that the threaded collar must have rotated over time; the o-ring didnt hold it in place. The air gap was .100"
After removing the gearbox, clutch, flywheel, they found the rear main seal is good, and dry. The massive oil leak was coming from the back of the intake manifold, running down the block. The underside of the car was a complete mess. The intake manifold would have to be removed and resealed.
They reinstalled the flywheel, Ram clutch and pressure plate, as they were still in very good condition, then set the air gap on the Tilton TOB to .200". Tilton recommends .170"-.230". Also on the threaded sleeve they sealed it in the back with something / silicone so there is no way it will rotate.
Next they removed the intake manifold and found that the engine builder, Lance Smith / Craft Engines put a minimal amount of silicone on, not nearly enough, and its been leaking for a long time. Very piss poor work. Grubbs removed and reseated the intake manifold with new FelPro gaskets and copious amounts of black silicone.
I asked for an engine tune checkup, and they found the inside of the MSD distributor was a mess, and one spring missing on counter weights. Looks like it rusted to pieces. They cleaned the distributor and installed new springs. The spark plugs were black and sooty from bad timing. They replaced MSD cap and rotor, replaced NGK spark plugs, changed idle air bleeds in carb to .073", set timing from 25 degrees to 35 degrees all in and 16 at idle. Much cleaner, great throttle response, less gas smell. Starts right up.
Michael Grubbs drove it around the block, said it has awesome throttle response, shifting is tight which is expected until the new synchro's break in, clutch has good feel, no chatter.
I picked it up Friday last week, its balls cold here (for Texas) so I just drove it straight onto the trailer. I'll get it out again when its above 55 degrees and see how it feels. But I'm already ready for some TEXAS HILL COUNTRY DRIVING in April!
For our Hurricane Cobra build I selected the Tremec TKO600 close-ratio gearbox with the 0.82 5th gear ratio, and Tilton internal hydraulic throw out bearing. It was fine initially, although I regret that 5th gear choice when we are doing 80mph freeway driving (more on that later).
After a year or so, I noticed it was getting difficult to shift back into first gear after coming to a stop. Then it continued getting worse and worse. The only resolution I had was to keep my foot on the clutch pedal and the car in gear while stopped at traffic lights or stop signs. It finally reached a point where it was difficult to shift into any gear once stopped. Something had to be done. I wasn't sure it if was a problem with the gearbox, the clutch/pressure plate, the internal HTOB, the clutch master cylinder size? Nothing I did seemed to resolve it. I gave it over to the experts, made an appointment with Grubbs Motorsports in Garland, Texas. They have painted, upgraded, repaired many mustangs, cobras, GT40s, even a few real, original 289 and 427 cobras.
Since Grubbs would pull the gearbox anyway, I decided to switch to a new gearbox. A fellow club member had a TKO-600 with the standard 0.64" 5th gear, that was almost new. I bought it, and took it to Texas Drivetrain Performance in Hurst, Texas for clean up and upgrades. They did bronze fork pad kit, carbon synchronizer kit, 2-3 shift rail modification, new front bearing retainer, new input and output shaft seals. He said it looked really new and clean inside before they started.
In the interim i had an opportunity to take the cobra to a track day at Motorsport Ranch in Cresson, Texas on November 29, 2023. I figured, why not? since I'm getting it serviced in a few weeks anyway. I ran four 30-minute sessions, and had a blast, the cobra drove better than expected, so much power! Other than down-shifting, especially 3rd-2nd so I as having to brake early, shift easy. Afterward I noticed a significant oil leak, dripping off the QuickTime bell housing. it had been dripping a bit prior to that date, but now it was a big puddle, very significant. I surmised the rear main seal had blown out. So I asked Grubbs Motorsports to also check that while they had the gear box out.
I delivered the cobra to Grubbs motorsports on Wednesday last week, after getting the replacement TKO-600 (with .64 5th gear) rebuilt at Texas Drivetrain Performance.
At Grubbs, they found the Tilton TOB was right against the clutch fork, and surmised that the threaded collar must have rotated over time; the o-ring didnt hold it in place. The air gap was .100"
After removing the gearbox, clutch, flywheel, they found the rear main seal is good, and dry. The massive oil leak was coming from the back of the intake manifold, running down the block. The underside of the car was a complete mess. The intake manifold would have to be removed and resealed.
They reinstalled the flywheel, Ram clutch and pressure plate, as they were still in very good condition, then set the air gap on the Tilton TOB to .200". Tilton recommends .170"-.230". Also on the threaded sleeve they sealed it in the back with something / silicone so there is no way it will rotate.
Next they removed the intake manifold and found that the engine builder, Lance Smith / Craft Engines put a minimal amount of silicone on, not nearly enough, and its been leaking for a long time. Very piss poor work. Grubbs removed and reseated the intake manifold with new FelPro gaskets and copious amounts of black silicone.
I asked for an engine tune checkup, and they found the inside of the MSD distributor was a mess, and one spring missing on counter weights. Looks like it rusted to pieces. They cleaned the distributor and installed new springs. The spark plugs were black and sooty from bad timing. They replaced MSD cap and rotor, replaced NGK spark plugs, changed idle air bleeds in carb to .073", set timing from 25 degrees to 35 degrees all in and 16 at idle. Much cleaner, great throttle response, less gas smell. Starts right up.
Michael Grubbs drove it around the block, said it has awesome throttle response, shifting is tight which is expected until the new synchro's break in, clutch has good feel, no chatter.
I picked it up Friday last week, its balls cold here (for Texas) so I just drove it straight onto the trailer. I'll get it out again when its above 55 degrees and see how it feels. But I'm already ready for some TEXAS HILL COUNTRY DRIVING in April!
