Thread: GM metric gears

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Does anyone have a set of 4.56 or 4.88 for the GM metric rear ends they would like to part with? Can't use anything but the stock rear end and a mini spool in Greg's car, only RPMing about 5200 with the 4.11 in it now......

Dave, what have you put in the engine to make power up any higher? What trans do you have,and what gear do you run it in? I built a very healthy 355,ran on1/4 mi. dirt and asphalt, found it ran the quickest with a wide ratio powerglide,in low gear with 3.73 rear end.We even took it to a 3/8 mile,and it buzzed up pretty high there. Didn't bother with a tach,he wouldn't look at it anyway. Hank

We're really limited on the engine in this class, 9.0 to 1 compression, cast heads with no porting or larger valves. Also had to make weight in the class, 3400 pounds. Also have to run a stock auto tranny with 3 forward gears and a reverse, so we have a 350 with a 2000 stall converter. Comes on good out of the corners, just need to get in the gear a bit deeper, barely touch 5 grand on the straight, engine is good to at least 6500. Oh yeah, also limited to a Rotten Rochester 2 barrel, so rate of acceleration on the engine is slowed considerably vs. what we could get with a 4 barrell.....

Dave, Do you run that in 2nd gear? How tall a tire? Are you allowed racing springs? I noticed in the pictures that the car sits pretty high. Our local tracks allowed a 500 holley,but only on a stock 2 bbl cast iron manifold.Before we were allowed racing springs we had to cut down any spring with a wire diameter under 17mm. Hank

Nope, no racing springs and yup on the second gear. Greg does the restarts in low, gets 2nd just before turn 1. Going to loosen up the Lower A-Arm bushings a tad. The car scales good, also have to run stock (spelled weak) axles in the rear end, if I set it too loose I'm concerned we'd snap the right axle if he pitches the back in too hard. Next year I'll be building an IMCA stock car for him and will be able to run some race car parts anyhow. This stock stuff really limits what you can do as far as adjustments......

Dave ,There's lots you can do in that gray area in between the rules,depends mostly on the tech inspector at the track. I've been involved in about a dozen metric chassis cars,don't recall ever snapping an axle.They must be made pretty well.Gm offsets their engines 2 in. to the right,putting it back on center and shove it back an inch or three. Lessens the need for rf spring rate by 150-200 lbs. I've gone so far as sectioning the cross member and moving the upper half around to hide my tracks,also moved both upper a-frame mounts 1/2 in. to the left.If they don't say you can't ,doesn't that mean you can? Hank

Done all that stuff, too. Unfortunately, the rules do not leave a lot of gray area and very specifically mention moving the engine back or to the left. Must be an old racer that helped write the rulebook, huh?