Chevrolet 305 CI Engine Build - Trans-Mission 305 Part 1
Out with our Bitchin' Camaro's wounded slushbox, in with a slick-shifting T56
From the February, 2005 issue of Chevy High Performance
All contributors: John Nelson
As we created a tire-smoking 305 Camaro in our "Mission 305" articles (June and Sept. '04), we were also exposing the '92 RS' weaknesses. We churned out 257 horsepower/295 lb-ft at the wheels right before the Camaro's original 700-R4 decided it was kaput--permanently. Disappointing, to be sure, since we felt like there was more power to be found. Unwilling to let the issue lie, we evaluated our transmission options and decided to go top-drawer by backing our potent 305 with a T56 six-speed.
Do we have to convince you that putting a six-speed into a hot third-gen is cool? We didn't think so. The T56 is strong enough to handle whatever power we get out of our 305; more of that power will get to the tires through the manual box, and the double overdrive will make The Bitchin' Camaro an open-road warrior. Best of all, we'd get to stir our own cogs.
Our first thought was to find a T56 from '93-97 F-body. These gearboxes are becoming more difficult to find, though, and when unearthed often need rebuilding. Other necessaries are also getting harder to locate, so we went the "new" route and installed a Tremec T5 replacement T56 as prepared by Rockland Standard Gear. The advantages? We got a new six-speed, ready to replace a factory five-cog box and able to incorporate the factory speedometer drive. Rockland also sent one of its blueprinted "Race Ready" boxes, making this one stout, slick-shifting outfit.
In the same vein, Spohn Peformance's Adjustable Torque Arm and Crossmember kit, along with the company's Extreme Duty Driveshaft, were bolt-in installations. As a bonus, Spohn's setup connects the torque arm to the crossmember rather than the transmission. According to Steve Spohn, this removes large amounts of stress from the tailshaft housing. Another advantage is that the pinion angle stays where you set it (1 degree down in our case). Spohn says that the stock mount and bushing can allow pinion angle to move as much as 2 or 3 degrees "up" under hard acceleration--with this setup, he told us, the pinion angle is "going nowhere."
On the other hand, we were replacing an automatic trans, not a T5, which immediately turned this into a custom job. Let's be clear on this: Even if you manage to find a complete T5 pedals/hydraulics/bellhousing/clutch setup, custom work is required to make the T56 fit. The owner of our guinea pig RS, Ryan Rivers, is a fabricator and street rod builder by trade, so none of this dissuaded him. We decided to go one-stop clutch shopping at McLeod Industries. There is, of course, more than one way to skin a Camaro. But we will tell you this--our setup works. McLeod's master and slave cylinders are great improvements on the plastic factory pieces; the scattershield could repel light artillery fire (McLeod also provided the correct adapter plate to mate tranny and bellhousing), and the 12-inch Dual Performance Clutch McLeod's Red Roberts prescribed is exceptionally smooth on the street and bites like a piranha when you nail it--perfect for an aggressively driven street car.
Was this an easy job? No. Was it worth it? We say yes. The Bitchin' Camaro sports the best of both worlds: a tranny and clutch combo that provides low-effort shifting and clutch action during daily driving, and also handles the rough stuff with aplomb. At a nice and legal 70 mph, the 3.42:1-geared RS turns a paltry 1,942 rpm in sixth--and at 100 mph, it's still only turning 2,775 rpm. And one more thing--there's no doubt that we're getting more power to the wheels (the words "it hauls ass" were used). As for how much more power, well, that's a tale for another day. With that, here's Part One, taking us as far as the clutch. Next month, we'll show you how to get that six-speed in its proper place.
(The author would like to thank Barry White's Street Rod Repair Company, 1640 Commerce St., Corona, CA 92880; 951/273-9284, www.barrywhitesrrc.com, for the use of the shop and for letting us burn lots of midnight oil while completing this story.)
We start with our 700-R4 and...
We start with our 700-R4 and all its running gear removed from our subject '92 Camaro. That leads us to the pedals. They're held in by four studs, which pass from the brake booster and through the firewall (arrows), and by one screw, hidden behind the dangling brake light switch. Undo the appropriate hardware and two switches and the automatic brake pedal pulls right out.
Fourth-gen pedals need minor...
Fourth-gen pedals need minor modifications to go into a third-gen Camaro. We sliced off the accelerator pedal bracket, since our original would stay in place. The top holes on these pedals are smaller than on third-gen pedals, so they'll need to be drilled out. Also note the cruise control and brake light sockets; the originals snapped right into place.
McLeod's clutch master cylinder...
McLeod's clutch master cylinder fits just like an original unit, but is steel rather than plastic and has a larger bore for more fluid displacement. Ryan test-fitted the piece into the pedals and adjusted the length at the clevis end (1), leaving about 1/8-inch clearance for the firewall. Also note the neutral safety switch (2); we'll come back to it later.
We then set aside the Camaro's...
We then set aside the Camaro's master cylinder and pulled out the brake booster. Two bolts in the booster holes were used to hold the new pedals in place. With the assembly temporarily bolted in, the clutch master cylinder bracket shows us exactly where to drill.
Which we then proceeded to...
Which we then proceeded to do, drilling our two bolt holes first, then making the big cut for the master cylinder with our 1-1/2 inch hole saw.
Unlike a stock unit, the McLeod...
Unlike a stock unit, the McLeod master features threaded holes in the firewall flange, so there was no messing with the stock U-bolt. After installation, be sure to readjust the master cylinder rod at the clevis joint so that it makes a full stroke into the cylinder (i.e., the pedal is fully up), or the slave cylinder piston won't fully extend nor the clutch fully disengage. Also remember to use the proper clip on the shaft end, or it may slip off and you'll have no clutch at all.
With this done, we installed...
With this done, we installed a clutch fluid reservoir on the firewall and ran the appropriate hose down to the clutch master cylinder. Look closely, and you can also see that we've installed the AN fittings and stainless hose onto the clutch master cylinder (arrow). With that, we moved to the Camaro's underside.
Before installing the motor...
Before installing the motor plate section of McLeod's beefy scattershield, we cut 1-1/4 inch off the bottom flange, and took a corresponding amount off the bellhousing to maintain our lowered Camaro's ground clearance. We used a 168-tooth steel flywheel to allow the use of a 12-inch clutch, but this necessitated changing to a large-flywheel starter. McLeod recommends a bullet-nose type as a guard against jamming. Note that a pre-creased part of the plate must be knocked out to accommodate the starter.
Using the correct pilot bearing...
Using the correct pilot bearing or bushing is critical in all clutch setups, but even more so here, since we'll be placing a 1/2-inch adapter plate between the transmission and the bellhousing. McLeod provided us with the hat-style bushing on the left, which fits perfectly into their flywheel and puts more bushing material towards the transmission, better supporting the input shaft.
The McLeod Dual Performance...
The McLeod Dual Performance clutch we installed is one of the smoothest, lowest-effort clutches ever driven--but the thing also grips like crazy, thanks to these flywheel-facing Kevlar "lock buttons."
While using the proper guide...
While using the proper guide tool to install the disc, we can see the full organic pressure plate side of the disc. According to McLeod, this material slides on the pressure plate as the clutch is engaged, which creates that easy pedal feel.
Keeping the clutch alignment...
Keeping the clutch alignment tool in place, we then installed the diaphragm-style pressure plate. Holding the flywheel in place with the proper tool and making sure the disc didn't slip, we torqued the pressure plate bolts to the specified 40 ft-lbs. Voila, we've got a clutch. Next month, we'll get it properly mated to out killr six-speed. Be sure to tune in.
We continued by installing...
We continued by installing the necessary adapter plate onto the McLeod scattershield. The adapter that Rockland Standard Gear sent was drilled to work with a stock T5 bellhousing, which corrects for that box's 18-degree tilt. We could have easily redrilled it to use with our "straight-up" bellhousing, but McLeod just happened to have one with the proper holes on the shelf, so we grabbed it.
Using the McLeod scattershield...
Using the McLeod scattershield necessitated using the proper McLeod parts to go with it. The adjustable ball stud uses an extra-large head to prevent slippage, and mates perfectly with the throwout fork. (A stock T5 fork won't work here.) When installing the throwout bearing, be sure that both the fork end and the spring clip go into the channel on the bearing.
As we said, our ball stud...
As we said, our ball stud was adjustable. Ryan drilled an extra hole so that he could adjust the stud to its proper height without removing the adapter plate. Here, off the car, he sets a starting point.
Here's the scattershield and...
Here's the scattershield and adapter plate in place; once the clutch slave cylinder (also sourced from McLeod, also made of steel, and featuring a very cool bleeder valve) is in place, we'll be ready for final setup via Ryan's adjustment hole (arrow).
Ryan created the bracket to...
Ryan created the bracket to mount the slave to the bellhousing. To set the proper throwout fork travel, the ball stud is adjusted so that there is a 1/8-inch gap between the throwout bearing and the pressure plate fingers when the slave cylinder shaft is fully retracted. The fork should point slightly forward towards the engine. When the pedal is pushed (after filling and bleeding the system), the slave cylinder piston should extend all the way, traveling 7/8-inch and fully disengaging the clutch.
Ryan's grandfather, Gene White...
Ryan's grandfather, Gene White (seen in our lead photo), ran a clutch and brake shop for 30 years, so he stopped by to keep the kids in line and make sure our clutch was properly set up. Here, he's inserted a measuring rod through the bellhousing and to the inside edge of the pilot bushing. As you can see by Gene's mark, our clutch disc will end up right where it should, and the input shaft end will have plenty of bushing to ride on. Thanks, Gene.
|T56 Swap Parts List|
|Rockland Standard Gear|| T56 six-speed for T5 swap, "Race Ready"(2.97, 2.07, 1.43, 1.00, 0.80, 0.63:1 ratios)||1386-000-011RR|
|McLeod Industries||GM Bellhousing assembly||8630|
|168-tooth steel flywheel||460260-1A|
|Chevy adapter pilot bushing||8617|
|12-inch Dual Performance clutch disc||260873|
|12-inch diaphragm-style pressure plate||360820|
|GM adjustable throwout bearing||16505|
|GM adjustable ball stud||16908|
|Clutch master cylinder (w/90-degree fitting added)||139001|
|Clutch slave cylinder w/ bleeder||139024|
|Braided steel hydraulic line, 24-inch AN4 female||139100-24|
|Fitting, male roll pin end to AN4||139026|
|Spohn Performance||Adjustable torque arm kit (includes crossmember)||322|
|Extreme-duty driveshaft for T56 swap||LMC-145|
|Classic Industries||'91-92 Camaro lower shift boot, upper console||G7595|
|Billy Graham's Camaro/Firebird Salvage||One used set of fourth-gen Camro manual trans pedals||--|
|Richard Hibbard Chevrolet||Vehicle speed sensor for manual-trans car||10456087 |
|(ACDelco 213-196)Speedometer driven gear (19-tooth)||14090592 |
Billy Graham's Camaro/Firebird Salvage
970 Hwy 202, Dept. CHP
Richard Hibbard Chevrolet
191 S. Indian Hill Blvd., Dept. CHP
Rockland Standard Gear
1600 Sierra Madre Cir.
494 E Lincoln Ave.