probs with my T5

blk94xlt · Post by **blk94xlt** » Mon Dec 17, 2007 3:14 am

Hi all.. got off my butt and worked out some issues on the truck and got to drive it a little more. But now I'm having some problems with gears grinding on the T5 that I put in.
I got the trans on ebay a long time ago and it was claimed to have been freshly rebuilt (from darkhorse performance if I remember correctly) but never used. When it arrived the box had an old darkhorse shipping tag on it and it had a little box with old bearings and stuff so I kind of believed it.
Ok, enough of that... my problem is that when shifting into 3rd and 4th gear it grinds. Sometimes at low speeds it will shift smooth but it seems like if I am going faster it is worse. 1st and 2nd gear are nice as can be though.

I'm not familiar with the guts of a T5 at all so I am asking what those more knowledgeable think the problem could be. Synchros for 3rd and 4th bad maybe since low speed works better??

Should I have someone rebuild the whole trans or is the T5 something I should take a stab at?

cgrey8 · Post by **cgrey8** » Mon Dec 17, 2007 8:21 am

It sounds like the synchro teeth are rounded off to me. It may have been rebuilt and someone just didn't catch that 3rd had rounded teeth. I think the teeth are also referred to as dogs. When they get rounded, the affected gear doesn't want to shift quickly anymore without grinding because the teeth don't want to catch each other. However they may still shift if you are easy on it.

I bought a video on rebuilding the T5 a while back and I was very impressed by how easy they are to rebuild. There's just lots of parts and names for each part that are a little intimidating, but nothing in the rebuild looked "difficult" to do. If I had a T5 that needed rebuilding, I'd give it a shot after watching that video. However, without the video, I'd be guessing at a lot of stuff and no doubt would've done a lot of stuff just flat wrong. The video I bought is from a guy that works for a Ford dealership as a master mechanic. Here's a link to where you can buy the video:
How To Rebuild the World Class T5 Transmission by BadShoe Productions

I bought this video because the same guy made a video on how to rebuild the 8.8" RE which got me through doing that too. I was so impressed by his coverage that I decided to order the T5 and AOD video just for educational value, not because I needed them. He's planning an AODE/4r70w rebuild video soon. He says the differences in them and the AOD are enough to warrant a separate video. If I ever do a tranny rebuild, it'll most likely be on a 4r70w, so when that one comes out, I'll be buying it too.

However I believe Malcolm said he bought a similar video on rebuilding the T5 for cheaper. I can't say anything about it since I haven't seen it, but it obviously had enough info for him to rebuild his Red Ranger's T5.

MalcolmV8 · Post by **MalcolmV8** » Mon Dec 17, 2007 6:53 pm

First I'd make sure your clutch is in good shape and releasing properly.

Chris I doubt someone just missed those syncros as the rebuild kit replaces all of them. Not just selective syncros. Also be sure you are not running mobil 1 full syn gear oil. I had a similar problem when doing that. The theory behind that (so I've been told) is that the friction surface on the back side of the syncro can't grab on good enough to stop the gear's from spinning when the syncros engage. I never realized it myself until I rebuilt my T5 but when you shift gears there's a smooth friction side to the syncro with a fiber surface that builds up friction against the gear. It looks just like a bearing race. That's what stops a gear/syncro combo from spinning right when the toothed side of the syncros engage.

Anyhow I rebuilt the tranny in my red truck. A press is an absolute must. I'm sure there are weird ways of getting around the various tasks but I used it extensively in my rebuild. Some good quality snap ring pliers too. I think I went through 2 or 3 cheap harbor freight pliers rebuilding mine. Oh and a rebuild video is invaluable if you've never done it before. I'm sure you could do it from a manual but what a task. Having someone rebuilt a unit right in front of you while you watch and follow along is a big help. Plus you can pause and rewind a few times while scratching your head figuring out what's going on

Later
Malcolm

blk94xlt · Post by **blk94xlt** » Mon Dec 17, 2007 8:03 pm

uh yep... that's the trans fluid that I used. Mobile 1 fully synthetic ATF is what you are referring to correct? I used that cause I thought it was better. I read that is the oil that they used right out of the factory on my '04 mustang GT with a manual 5-speed trans. I know that they don't have the same trans but I have never heard that the Mobil 1 full synthetic ATF would cause problems in a T5. My T5 is supposedly from a 93 cobra.
That would be great if all I had to do is drain the fluid and put the right stuff in. You are saying that you had the same problem with gears not going together without a little grinding? What type of trans fluid did you end up changing to?

cgrey8 · Post by **cgrey8** » Mon Dec 17, 2007 8:17 pm

I ran Mobil1 ATF when I got my tranny. It shifted fine for me. When I dropped the oil after 15k and refilled it, I put normal DextronIII/Mercon in it and it did seem to shift a little better, but it was not worlds difference and I certainly never had grinding. But then again, my tranny was brand new, not rebuilt.

But this isn't the 1st I've heard of Mobil1 causing the manual tranny to not shift as smoothly. The benefit of Mobil1 ATF is much better in a real automatic where it's temperature tolerance properties are really put to the test. Manual trannys are just gears meshing & need lubrication to do that. The only heat-generating "friction" surfaces are the synchro surfaces Malcolm was referring to and they are only rubbing in the middle of a shift which lasts less than a second (i.e. it's negligible). Of course the meshing of the gears and agitation of the fluid will generate heat similar to the heat produced in a rearend, but nowhere near the heat produced in an automatic. Plain ole Mercon will do just fine, just change if OFTEN (i.e. every 2nd or 3rd oil change).

MalcolmV8 · Post by **MalcolmV8** » Mon Dec 17, 2007 9:05 pm

I ran mobil 1 full syn ATF in my T5 and as I shifted I could feel a catch. A very small grate as it went into gear. After searching the net I read a lot of reviews on GM synchromesh. It's a full synthetic ATF/gear oil blend for manual boxes. It is by far the best shifting oil I've tried.
Your mileage may vary.

Malcolm