After the unit has been cleaned,...
After the unit has been cleaned, transmission specialist Kevin Carpenter pulls the side cover. This component also contains some small shift linkages that connect to the shifter forks, so be careful not to lose anything when it comes out. Now you can lift the shifter forks out of the transmission.
If you race on Saturday nights on asphalt, you are probably running a T10 transmission or some derivative of it. The T10 four-speed manual transmission appeared in passenger cars in the '70s and '80s, mostly in GM performance vehicles. And components for this design are still being produced today, so parts are plentiful and you can stay away from junkyard shopping. Racers like them because they are simple, relatively small, tough, and fully mechanical.
But despite its hardiness, the T10 should occasionally be rebuilt and inspected for damage or excessive wear. If you race a full season, plan on a rebuild during the off-season to prepare yourself for trouble-free racing when the next season begins. Tex Racing, which specializes in everything gear related and works with race teams from the NASCAR Nextel Cup level all the way to Street Stockers, maintains as many T10's as it does its own T101A design, which is a favorite of the Cup guys.
Manager Tony Hancock says that since the T10 was originally designed as a street transmission, it requires a few specialized steps not normally needed for a race-only unit like the T101A, but any racer with decent mechanical skills should be able to tear down and rebuild his or her T10. The first step, obviously, is to get a rebuild manual, but we also followed along as Tex Racing rebuilt a tranny for a local Late Model racer. In addition to checking for wear and rebuilding this piece, transmission specialist Kevin Carpenter showed us a few tricks as he worked his way through this unit. If you attempt to do your own rebuild or make repairs to your T10, you can acquire rebuild kits and replacement gears from many racing supply houses or directly from Tex Racing.
When it comes to transmission upgrades, the first thing Tex Racing recommends is having all the gears and shafts REM polished. This creates a smoother, harder surface that cuts both friction and heat.
Once you've done that, you may want to get into lightened gears. You can purchase lightened sliders, which cut the weight from 2.12 pounds each to 1.68. A lightened reverse gear cuts the weight from 2.78 to 1.76 pounds. Both cost approximately $100 each. A gundrilled main shaft cuts the standard shaft's 10.86 pounds to 8.7, but costs significantly more at approximately $550. If money is tight, the lightened gear and sliders are much more preferable since the weight being removed is further outboard; we all know that when it comes to a spinning mass, the further out you can remove weight, the better. Finally, you can use an aluminum reverse gear, which weighs only 0.70 pound, but it is practically useless and should only be installed if your rule book requires you to prove that you have a reverse gear. If you are spun on the racetrack and need reverse, you are just about guaranteed to strip the aluminum gear.
 Each lightened slider can...  Each lightened slider can save you nearly half a pound of rotating mass inside the transmission. |  A roller bearing main shaft...  A roller bearing main shaft (bottom) helps prevent galling between the shaft and the transmission gears. |  A lightened reverse gear (left)...  A lightened reverse gear (left) shaves over a pound of weight. It is still heavier than an aluminum gear, but it won't let you down if you need reverse on the racetrack. |
A final option is to upgrade to a roller bearing design (main shaft and bearings). This doesn't necessarily put more horsepower to the track, but it is good protection for your transmission because the main shaft depends on splash oiling. The roller bearings can definitely help prevent galling between the shaft and the gears.
As we said earlier, rebuild manuals, kits and replacement gears are readily available from many different supply houses. Go get 'em and have fun getting your T-10 ready for a new season of racing.