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It has a 3.67 rear end ratio with an 80% ZF limited slip. It should hold the power, but the torque tube is the weak link now. I rebuilt a new torque tube setup tonight, with solid aluminum torque tube crossmember bushings, an Opel GT Source heavy duty torque tube donut (nice!), heavy duty European torque tube side mounts, and OGTS urethane top and bottom bump stops. I also took the torque tube bearing assembly apart, soaked the bearing itself in solvent, and repacked it with Amsoil synthetic grease. I then glass-beaded all the parts and painted them with black POR-15, except for the torque tube itself. I'm having it chrome plated by a friend of mine.

The tranny is a Getrag 240 5-speed, but it's already starting to make noise too. We'll probably put a Getrag 265 in, or perhaps a Quaife close-ratio Ford T9 tranny.

Bob
 

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That concerns me Bob, about the rear-end I mean. I've got a ZF 3.88 posi NOS from Germany. I've got all of Gils new bushings in it. When I had the Pro-Gear folks here inSANe DIEGO put it all together, I also gave them Gil's number to replace anything that was bad in the unit. The whole assembly is, for all intents and purposes, new. Now I'm curious if it will hold together with the 3.4 V-6 and T-5 tranny. I'd hate to lose $1500 by driving a little too much like fun!! Watcha think?

Ron
 

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The limited slip can handle it. The gears are okay up to about 220-240 hp of hard use. Be SURE to change gear lube regularly, the one failure I've seen a lot of on Opels that are driven hard is a failed pinion gear due to bad bearings. A seized pinion bearing will shear the pinion gear in half...if that happens, no more expensive gear set! I use synthetic gear only once I've broken the differential in.

The torque tube is a more likely failure point. The donut, side mounts, and top and bottom stops should be new and of the 'heavy duty' variety. But the torque tube driveshaft itself is known to fail under duress. I have prepped them in the past by welding a 1.5" tube around the T/T to support the skinny shaft, which tends to 'whip' and get into a harmonic situation, then fail. I did this for my hillclimb Manta because of the 4.75 rear gear and welded differential. With slicks, it will expose the weak points very quickly! That being said, the stickiness of your rear tires will have a lot to do with the potential for rear diff failure.

Bob
 

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If what Mike Pilkenton says about his 3.1 mod, the tires don't "stick" too well under hard acceleration in the first 3 gears, so maybe I'll be o.k. I've got all of Gil's heavy duty stuff in this one. He knew I was doing this mod so he recommended all the good stuff. If I lose the shaft, maybe I can get one built up from 4130 chrome-moly or maybe the more exotic stuff out there now. Let's see, back in the boat racing days we got a 1" shaft for about $125. Cut with splines and a gear for a short duplex motorcycle chain to hook it up direct to the nose of the crankshaft. It sholdn't be more than that today:D

Ron
 

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namba209 said:
If what Mike Pilkenton says about his 3.1 mod, the tires don't "stick" too well under hard acceleration in the first 3 gears,
Sorry, I should have clarified, I meant the actual adhesion of the tires. For example, a BFG Radial T/A will not stick the same as a Falken Azenis, etc. My dad has a supercharged Jaguar with Pirelli P-Zero's, and they are unbelievable in terms of traction, at least for a street tire. If it had lesser tires, it would probably be uselessly slow because of wheelspin.

Bob
 
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