Tremec troubles? Help!

[flanker]

I was running my Cobra at Homestead speedway this past weekend on the road course and did 2 1/8 mile passes. on the way home my tranny would not down shift in to 2nd. I have a 3550 tremec. The car up shifts fine but will not go into second from third even at low speed. have to slow down enough to go into first then pull up into 2nd.

Any ideas or help would be appreciated. Going to Gainseville in 2 weeks and need to be ready

Forever Bitten
Frank H

[agro1]

Sounds like a synchro...Will it go into gear if you match the revs ?

[RallySnake]

Frank,

Man, I thought these Tremecs were bulletproof! I agree with Agro, it really does sound like the synchro is worn out. That is a big job, too. The whole transmission has to come apart. If you can't do the next event the way it is, better cancel. It usually takes me a day to get the trans out, a day to take it apart (very carefully, noting everything), a few days to find the parts, a day to put it together and a day to install it. And I only get to work on it on the weekend.

Have you drained the oil and checked for pieces?

Good luck,
Paul

[Cal Metal]

Before tearing it down, examine the internal shifter rails/components to see if they are binding. It sounds as though the outside synchro hub is not moving at all on the splined internal hub. It could be seized but I would check the action of the rails and forks before tearing everything apart.

Also, if one of the dogs on the synchronizer is broken, that would prevent the shift from happening, by creating a cocking action on the sychro unit. A loose sychro unit will normally create a situation where the shifter pops out of gear as opposed to preventing shifting into that gear.

[RallySnake]

Cal,

Could you get to the second gear synchro though the top plate? Is is possible to slide a screwdriver in there and unstick the synchro?

Paul

[coyled]

Frank, its not the syncro. In a tremec, on the underside of the first to second slider gear and the third to fourth slider gear, there are 3 little detents held in by springs/ c-clips. These detents are about 1/2 inch by 1/4 inch rectangles with 1/8 inch sides. When you pull it apart, I will bet you anything the detents have broken ends in the first to second gear slider. I had the exact same problem on my first tremec. I would try adjusting the clutch out to see if that helps, but I would bet money that those detents are broken. It will still shift, just a lot slower as the syncros have to slow the gear all the way down before it shifts. It should still shift without the clutch onse the gear slows. Hope I am wrong, though, good luck. scott

[agro1]

Frank - does it grind when you try to put it into 2nd ? If it does, try matching the revs and downshifting (heel toe). If it goes in w/out grinding when you match revs you will know it's a synchro. Sorry man - I feel for ya...

[RallySnake]

Scott,

How did you break your's?

Paul

[coyled]

After road raceing the cobra, it had trouble downshifting into second. I pulled it apart and found the broken detents. scott

[Cal Metal]

Paul:

The "dogs" I was referring to in my first post are the same thing that, I think, Coyled is referring to as "detents" on the Tremac, although our terminology differs.

The gears don't technically slide. The gears free wheel on the mainshaft and the splined synchro unit engages the clutch teeth on the free wheeling gear via the brass ring (which slows down the rotating gear) on the gear cone.

People sometimes refer to the brass ring as the synchro. If that is what Colyed is referring to, he is correct, and that is probably not your problem. Technically, the synchro unit is made up of a hub which is splined internally, fitting on to the mainshaft. The outside of the hub is also splined with three provisions for the "dogs" which float via two C springs which press against the dogs from the bottom. A splined slider or clutch hub is fitted over the entire unit, and it is that slider that engages the brass ring and clutch teeth on the gear, thereby mating the synchronizer with the gear to be driven.

The purpose of the dogs or detents is to provide smooth action when engaging a gear by providing a floating action. Without them, engagement would be much more difficult, as some binding would occur. If they are broken, this binding will occur and/or pieces can become jammed in the synchronizer which would prevent a shift.

It will still require a tear down. Use a magnetic pickup to see if you can retreive the broken pieces, if that in fact, is the problem.

[computerworks]

(...image courtesy of Cal Metal)

[Cal Metal]

Thanks, Ron, for putting that pic up for me.

The "inserts" are what Coyled and I are referring to as a potential problem. They may vary in size---this is a schematic of a Toploader 4-speed, but the principle is the same.

Notice, too, that the brass synchro ring is absent as it fits onto the gear not the unit.

[Chad Johnson]

Pay attention to coyled. I just fixed that very problem and it is the
syncro insert (part #2602648) that has failed. These things are made out of untreated stamped sheet metal and probably cost about .02 each.

My R&R of transmission cost me a total of $300+ (I replaced all the syncho blocking rings since I had it apart)with me removing and reinstalling the transmission. A real bummer for a failed .02 part.

Good Luck

[Cal Metal]

Coyled and Chad:

Are you guys also running 3550s?

[Chad Johnson]

Cal,

I am running a TKO that is very similar to 3550 other than 26 spline input shaft (versus 10 for 3550), 31 spline output shaft (versus 26 for 3550) and larger diameter extension housing. Most of the rest of the transmission is the same (particularly the syncro inserts).

Hope this helps.

[Dr_lopez]

Hey Frank, looks like we're both up a creek without a paddle, huh!! We even have similar problems... I messed up my tranny too!!!! Not the same symptoms.. Mine goes into all the gears, up and down, without a hitch, but it 's making a lot of noise. Loud winding and howling from 1st thru 3rd and some noise in 5th. Anybody got an idea what it could be?


CobraDoc

[RallySnake]

CobraDoc,

I am really sorry to tell you the bad news. My guess would be countershaft bearings. I've destroyed and replaced a few.

The reason it doesn't grind in fourth, is that power goes straight through the main gear stack and not thought the countershaft.

My advice is, don't drive it until it's fixed or you may be buying a new counter shaft and the gear cluster, too. Also, I'll bet lots of little ground up pin bearings are floating around in your oil.

While you have the drain plug out, make sure it has a magnet on it. if it doesn't, epoxy a small rare earth magnet to the concave face of the plug. Let the epoxy set up overnight in a warm place before installing the plug.

I hope this helps and you get it back on the road soon,
Paul

[Jeff Frigo]

Only one trans. less bulit proof than a 3550, its the T-5. It was a matter of time before I would wipe out 3rd. gear on a 300 hp 5.0. Happened to me a friends of mone many times.

[flanker]

Thanks everyone for the help. It is going to my mechanic tomorrow because i do not have the time or the talent to pull it apart and fix it myself. i will let him know what you guys said. i appreciate the help and the fast response.

Forever Bitten
Frank H

[Dr_lopez]

Me too, THANKS for the advice Paul even though it's not what I wanted to hear. S#%t, that means I won't be driving my beast for a while.