Tremec 5-speed conversion for C2?

[Bill M.]

Re: Tremec 5-speed conversion for C2?

Second gear synchros are usually the first to go for most drivers, and the cause is downshifting. The problem is non-existant to those who double clutch downshifts.
Duke

I double-clutched all downshifts with the Ford. The cause for my second-gear synchro problem was too big a gap from first to second and shifting it fast (like I shifted my '59 T-10). (This cause was confirmed by a local expert who does nothing but rebuild transmissions.)

I'll bet you're right for my T-10. I drove that for years before I learned the double-clutch technique.

[Gordon A.]

Re: Tremec 5-speed conversion for C2?

We have installed several Keisler Tremec packages in both big blocks and small blocks; in both C-2 and C-3s. Everyone has loved them. The shifting is smooth and precise. We have had NO warranty issues of any sort.

Because the first gear ratio is extremely low [lower than stock] and [of course] the fifth gear is an overdrive [two choices available], you have a lot of options for a rear end ratio.

Keisler's website has a fun "calculator" where you plug in your tire size, your rear end ratio and you get to see your rpm's at various speeds.

Fitment is relatively easy with no body or chassis modifications. We highly recommend them.

[Duke W.]

Re: Tremec 5-speed conversion for C2?

Fast upshifts can wear synchros. Ideally you should upshift such that the countershaft speed has dropped to the mainshaft speed corresponding to vehicle speed in the next gear. This is influenced by how fast the revs drop and gear spacing. Each combination has a "natural rhythm" that I try to follow. Fast rev drop off and close gear spacing mean you can shift fairly fast, and if you develop the technique sufficiently, you can upshift without the clutch.

I experimented with this, but abandoned it because I could not get it dead nuts on on every shift - maybe three out of four.

With a well developed technique, T-10s and Muncies are very long lived, but like most other transmissions, will not survive a lifetime of "drag racing" type shifts.

Duke

[Stuart F.]

Re: Tremec 5-speed conversion for C2?

I've been running tall gears (rear ends) for many years with both T-10's and Muncie close ratios. I don't have track time like Duke, and others, but I learned long ago how to do "Match RPM" downshifts, beginning with my experience with old Chevy 3-speeds in order to get into first gear on the roll. I agree that "heal and toe" and double clutching are fine for all out racing where you are using the brakes with engine braking, but for normal driving on the road Match RPM downshifting helps preserve both the tranny and the brakes. I do it all the time. The only wear I have seen with the tall geared arrangement is from the other direction, i.e. long windout acceleration tends to be hard on countershaft thrust washers. I rebuilt one from a 59 Chevy 335hp w/ 3.36 rearend and a BW T-10 (cast iron case). The trust washers were actually welded to the case.

Stu Fox

[Bill M.]

Re: Tremec 5-speed conversion for C2?

Fast upshifts can wear synchros.
Duke

I figure that the Ford synchro had to drop the input shaft rpm about 80% more than the T-10 synchro. I guess that was just too much for drag type shifts. I just stopped the fast shifts after I fixed it...no more problems.

Ideally you should upshift such that the countershaft speed has dropped to the mainshaft speed corresponding to vehicle speed in the next gear. This is influenced by how fast the revs drop and gear spacing. Each combination has a "natural rhythm" that I try to follow. Fast rev drop off and close gear spacing mean you can shift fairly fast, and if you develop the technique sufficiently, you can upshift without the clutch. I experimented with this, but abandoned it because I could not get it dead nuts on on every shift - maybe three out of four.
Duke

I experimented with this (on company Ranger trucks; great gearbox) for both upshifts and downshifts. On downshifts, matching revs in neutral (so the synchro wasn't needed) and just pulling it into the lower gear with no clutch.

With a well developed technique, T-10s and Muncies are very long lived, but like most other transmissions, will not survive a lifetime of "drag racing" type shifts.
Duke

I know I've done a LOT more drag shifts with my '92 6-speed than I did with the Ford. I've had no synchro problems with the 6-speed...just a much better gearbox for that kind of shifting.

[Mark W.]

Re: Tremec 5-speed conversion for C2?

I have a '66 L79 and I put in the Tremec 5 spd from Keisler this past March. In a nutshell, I love it! I have the 3.70 rear end and at 75mph, it's turning 2100 rpms. On the other end of the gearing, if you drop it in first and let er rip, you easily smoke the tires and can have a lot of fun. I had a shop experienced with Keisler installs here in Colorado Springs do the installation (both owners have the Keisler installed in their own cars). There were no issues either during the install or since I picked it up. The shifter was a little stiff at first, which is explained in the literature, but as I drove it and broke it in, it smoothed out very nicely.

Keisler was very easy to work with and when I called my salesman on his cell phone on his day off, he still took the time to answer my questions.

[Joe R.]

Re: Tremec 5-speed conversion for C2?

I think you're better off with a Richmond Super T-10 wide ratio (2.64, 1.75, 1.31, 1.00:1) with a 3.36 or 3.08 axle. It's pretty close to a pure bolt-in and will probably be less expensive than a Tremec. The 3.08 yields about 2350 at 60 and 2600 with the 3.36, which is about 3100/3400 respectively at 80.

With the Special 300 HP cam and some compression, it would be a killer combination - near big block acceleration, 150+ MPH, and 20 MPG on the highway. Your heads have the flow!

Depends on the model, but most Tremecs have a stump puller first gear - much shorter than necessary - especially with a short axle ratio and have a HUUUUUUGE gap between fourth and fifth.

Comparing the "intergear ratios" of the Richmond and the WR Muncie is interesting:

Super T-10 1.51, 1.31, 1.34
Muncie WR 1.34, 1,28, 1.48

Note that the big gap on the Super T-10 is between first and second - the way a good transmission should be. You will hardly feel it, unlike the big 3-4 gap of the Muncie and even wider 4-5 gap on most Tremecs.


Duke

Hi Duke:

The Tremec version that I plan to get has the following gear ratios:

1st = 2.87
2nd = 1.89
3rd = 1.28
4th = 1.00
5th = 0.82

This yields inter-gear ratios of 1.52, 1.48, 1.28, 1.22. I think this is a pretty reasonable arrangement for street driving if the engine has a wide torque band.

I'm actually not too concerned about minimizing the 5th gear cruising RPM, as long as it is reasonable. That's why I plan to get the optional 0.82 5th gear instead of the 0.64. My current rear axle ratio is 3.70, which I plan to leave as-is.

By my calculations, my top gear will be roughly equivalent to a Muncie with a 3.08 rear, while my 1st gear will be roughly equivalent to a Muncie CR with a 4.88 or a Muncie WR with a 4.11. I think this will give me a good balance between "spirited" driving in the lower gears and "low cruising RPM" in 5th gear.

[Duke W.]

Re: Tremec 5-speed conversion for C2?

Yes, that's a good ratio set for just about any axle ratio. If I could choose ratios, I'd probably make third about 1.33 to close the 2-3 gap a little at slight expense to the 3-4 gap, and set fifth at about 0.78 but most guys probably wouldn't be able to tell the difference.

With the broad torque and power bandwidths that a good massaged head 327 can make, the ratio spacing need not be any lower than 1.28, which is the Muncie CR 2-3, 3-4 spacing.

As a point of reference the gear spacing on F1 cars is about 1.10 between all gears. Revs are rule-limited to 19,000 and you can see from the occasional on-screen telemetry that a shift at 19K drops revs to 17K. F1 engines are very peaky and the peak power bandwidth is very narrow. On the slowest second gear corners revs can drop as low as 7000 and the engines sound like they're barely running. A lower gear would not help since they are traction limited in slow corners due to lack of downforce. Once past the apex, revs climb quickly to 19,000 then stay in the 17-19K bandwidth through seventh gear, and they have to be shifted to a higher gear about every two seconds in the intermediate gears.

Duke