Tremec 3550 Question about shifts & fluids
 

Well, the ole girl is just about back together completely. I've been driving around a little with no tunnel (yeah, I know...) for the past week and was just about to get it finally assembled.

As some of you might recall, I broke the internal 5th/Reverse shift lever and had to have it replaced. I got the tranny back in the car and noticed something different about the way it shifted.

Before the "incident", it shifted very smoothly from each gear to the next. Now, there seems to be a defined "double click" movement. That is to say when shifting from first to second, for example, it pauses in neutral, and then continues to second. Same for second to third, etc. Downshifting as well. I'm assuming it has something to do with the synchros, but I just don't know. At
first I thought it was related to the Pro 5.0 shifter I got bought, but the old shifter does it as well.

One note of interest: When I drained the trans fluid, it was red in color, like ATF. What the service manual calls for is GM Synchromesh. I replaced the fluid with 3 quarts of Pennzoil Synchromesh (sams as GM) and was wondering if that could be the difference in shifting. It apparently has had the red fluid for 10,000 mile life of the car since the previous owner had never changed the trans fluid.

Any takers on this one? :)

I've always thought they used ATF.....

GM syncromesh is the fluid to use. I've seen it in different colors and don't know why, I just buy it from a GM dealer parts dept just to be sure.

same problem
 

Ive had the same "double click" feeling in my 3550, but it starts to happen after everything gets hot, and only from when i'm at a dead stop. My mechanic tells me its the synchros and to try Redline fluid. I know that Tremec doesnt recommend it, but my guy has been using it in Cobras etc... with no problems. Going to try it as soon as time permits.

I've been using the Redline MTL with no problems. Teh MTL is designed to work properly with the synchronizers. Take a look at their website www.redlineoil.com .

Bob

I ran the royal purple ATF in mine a while. shifted nicely, but got lots of new leaks. whiched back to synchomesh and no leaks....and pretty close to the same feel.

I would be careful. Synchronizers need friction to work, you put a synthetic such as red line or royal purple and you might not have the friction you need for the synchronizers to work properly. It always amazes me that "some guy" or "my mechanic" always knows more than the Orignal equipment manufacturer, wow they must be stupid. Use the gm synchromesh as stated and if you still have a problem then it is component related not fluid. I had a 3550 and it was the smoothest shifting transmission I have ever owned, I used GM synchromesh.

New info...

I spoke with Tremec for about 30 minutes today. Interesting what the tech guy told me. He said Synchromesh was recommended only for sound dampning reasons. Apparently the 3550 started out as a truck transmission in it's past life and the cut of the gears make more "whirring" than others. The Synchromesh is a slightly thicker fluid that helps tone the noise down a bit.

He clarified the ATF may shift better, but the transmission noise will be greater. When I told him what kind of car I had, sidepipes and all, he seemed to agree that ATF would be a better choice for my application. He did, however, mention that they only recommend a couple brands, and that Redline and Royal Purple wasn't one of them. He mentioned Mobil 1 and another. I forget which, but he said it really didn't matter. In the end, he recommended I find out what was in there and put that back in.

Interesting...

So now you are relying on mr GED customer service rep. The 3550 was never a truck transmission. The royal purple has the highest viscosity of any, it would run the quitest. They are all GL-5 compatible so why he would say no to some and not the others is only his un educated opinion. Use the sychromesh.

Ok... Let me break this down for you. I'm using the Synchromesh, and it sucks. Whatever was in there before was *FAR* better. As well, no one was relying on anyone. I just posted what the tech guy at Tremec said.

Let me get this right... You are suggesting I take YOUR advise over a guy who has worked for Tremec for years and has rebuilt and repaired the 3550 probably hundreds of times (three times I called Tremec over the past month and each time I got someone on the phone who worked in repair for several years).

I realize this post may seem a bit edgy, but your condescending attitude mixed with various silly assumptions (Mr. GED. etc) just seem to get on my nerves. Perhaps you could look into a bit more couth?

When I got my TKO600 it said in the instruction sheet to use Dextron III type ATF fluid.I use Castrol. I could not image such a big gearbox to shift so easy and so fast. Wonder why the 3550 should use a different oil.
The only leak was where the the speedo cable goes into the box. Some O-rings in the right place fixed that.

Bravo Humbucker on your "madmaxx" reply. He sounds grouchy. I have been told it was a truck trans also. I have also heard of leaks with Redline etc... , but my poor uninformed mechanic again tells me every one is happy with synthetic. Thanks for spending the wait time on the phone for all of us with this question!

just FYI, I found this on the net from tremec. It has been very helpful for me in many instances and has about everything you need to know about parts/rebuild. I am staying out of the fluid stuff....I just thought it would be a good source for people to save concerning the technical aspect of the trans. Part numbers are very helpful on here.

http://www.ttcautomotive.com/English...ice_Manual.pdf

Buzz

I too would think a good o-ring would solve that. As for the difference in oil, the guy I spoke to yesterday said the TKO500 & 600 gears are cut with a slight rounding of the edges to make them less noisy than the 3550.

I'm going to switch back to the Redline C+ that was in there before and see what happens. If there's a leak, I'll try the o-ring (I have about 50 of various sizes around the shop) and let you know, if you don't beat me to it. :)

also, note on page six of the PDF file, top left...they list Detron II type fluids as an "option" for filling it...so sychromesh or dextron II....from the factory.

The other fluid worked better what ever it was in my opinion because it was saturated with wear particles. These wear particles helped the synchronizers work better, please remember all the gears in your transmission are always fully engaged regardless of what gear you are. It is the synchronizers that you are engaging and disengaging not the gears when you shift gears. If you want your transmission to shift perfectly try this, when you are shifting gears push in the clutch and pull it out of gear and into neutral, let out on the clutch while in neutral, push back in on the clutch and shift to the next gear, if it shifts smoothely then it is a synchronizer problem if not then it is a shift mechanism problem. This is referred to as double clutching like you did in the old days before synchronizers were around.
Some history with transmission fluid. I had a Miata (let the flames begin) and it was the worst crunchy shifting transmission I ever had and the 11 other miatas I test drove were all the same, it always amazed me on how everyone complimented its transmission shifting characteristics. In my effort to get it to shift better I tried RedLine, Royal Purple, Castrol (non-synthetic), Honda ATF, Mazda fluid and Mobil 1. In the end the Castrol non-synthetic appeared the be the least of all evils. Bottom line is no fluid will fix a problem it may alter the way it shifts while the fluid reachs operating temperature but once they all reach operating temperatures they all shifted identicle. Note even though the wear particles help the synchronizers they do not help the bearings or gears so there is give and take for everything. The TK 3550 I had in my cobra in no doubt was the smoothest shifting transmission I ever owned, it would crunch going into reverse it I did not shift to 3rd first but if I pushed in the clutch shifted to third and while holding the clutch in shifted immediately to reverse it would go in like butter.