Fox Body Tremec T-5 Issue

[Kenz_88_Fox]

I have a 1988 mustang gt, I've only owned it for about a month, it has the tremec t-5 tranny with pro 5.0 shifter. As I was going down the highway I heard a knock in my tranny. I got off and realized something was wrong. It knocks in every gear except for 4th and only when I let the clutch out, as long as it's in neutral or the clutch is in it's fine. It sounds like something is bouncing around around and knocks faster the higher the rpms. Any idea what it could be or what I should do?

 

[fords2live]

What EXACTLY does it sound like? What could you compare it to? Vibration at all? Check the drive shaft bolts real quick, to just make sure, too..

 

[Kenz_88_Fox]

Doesn't have any vibration, more like maybe a bolt backed out of somewhere and is bouncing around in the tranny. It's a real loud knocking sound and like I said it gets faster the higher the rpms got.

 

[jrichker]

The cluster gear transmits power in every gear except 4th. You may have a problem in that area.

Diagrams courtesy of Tmoss & Stang&2birds

T5 Cutaway showing T5 internal parts

I don't know how you feel about the DYI thing when it comes to gears, some people don't like the idea of working on transmissions. If the DYI transmission fix idea isn't something that you would rather leave to someone else, here are some resources:

See http://www.ttcautomotive.com/English/onlineorder/product.asp to download a FREE service manual for T5 or Tremec 3550/TKO
You will need the Adobe Acrobat viewer which is also a free download – http://get.adobe.com/reader/

See http://www.hanlonmotorsports.com/ or http://www.ddperformance.com for parts

A T5 rebuild kit with syncros, bearings and other small parts costs about $160. It does not include any gears or shafts.

http://www.hanlonmotorsports.com/ also has a video on how to rebuild your T5 or Tremec. It costs about $20, and is worth every penny of it.

I did a Tremec 3550 rebuild, and it wasn't that difficult. The video was an immense help, and I would recommend viewing it. At $20, it will give you an opportunity to look and decide for yourself if you think that it is something you want to try to do.


T5 Shim kits – best product I have seen in a while… http://www.5speeds.com/t5/shims.html
“The Peel ‘n Place T5 World Class shim kit makes shimming T5 counter gear and main drive gears very easy.”

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

O2 sensor wiring harness
http://www.veryuseful.com/mustang/tech/engine/images/mustangO2Harness.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pin out
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

87-92 power window wiring
http://www.veryuseful.com/mustang/tech/engine/images/mustang87-92 PowerWindowWiring.gif

93 power window wiring
http://www.veryuseful.com/mustang/tech/engine/images/mustang93PowerWindows.gif

T5 Cutaway showing T5 internal parts
http://www.veryuseful.com/mustang/tech/engine/images/5_Speed_Cutaway_Illustrated.jpg

Visual comparison of the Ford Fuel Injectors, picture by TMoss:
http://www.veryuseful.com/mustang/tech/engine/images/Ford_Injector_Guide.jpg

 

[MFE92]

There's no sleeve that locks the two shafts together for direct drive, and even though it's a 1:1 ratio, the cluster still transmits power from the input shaft to the output shaft in 4th gear. However, since that's the only gear where the input and output turn together at the same speed, and that's the only gear there isn't any noise, I suspect there's a problem with the pocket bearing where the two shafts meet, or, the snout of the input shaft is galled up and ruined which is not uncommon. They even make sleeves to repair them.