Vintage Mustang Forums banner

1 - 8 of 8 Posts

·
Registered
Joined
·
26 Posts
Discussion Starter #1 (Edited)
Hi everyone,

this is a warning to everyone attempting to do a transmission swap on a 1st generation Mustang. We ran into this yesterday evening ... and it scared the bejesus out of us. It should have been easy to avoid, if we were made aware at any point in any instruction manual of the many new components we installed. However, that wasn't the case.

Here's the deal:

We are swapping a TopLoader 4-Speed for a Tremec TKO 500 5-Speed on a 1970 Mustang with a Ford FE 428 Cobra Jet. Therefore, we...
  • did a ton of research, calculations, prep-work, and talked to a bunch of manufacturers for purpose and fit.
  • decided to go with a Tremec TKO 500 5-Speed from Silver Sport Transmissions as well as the recommended RAM 1518 flywheel, 88994 diaphragm clutch and pressure plate, in combination with the original C5TA-7505-B bell housing which was already installed on the CJ.
  • pulled the old transmission, the original bell housing, the old Centerforce pressure plate & clutch, and pilot bearing.
  • installed all the new components, after carefully measuring run out on the bell housing (which was within specs, thankfully).
Yesterday evening, we finally had everything installed and were ready for 1st start. Long story short, the engine did about 7 turns under an excruciating grinding noise, before I was able to shut it down. Unable to explain what had happened or where this was coming from, we finally pulled the new transmission back out. There was a bunch of testing and checking going on and I will spare you the details on that.

We found the new pressure plate touching the original bell housing. Those 7 turns already did a lot of grinding on both the bell housing and the pressure plate. In the end, this locked the engine in place to a point where the starter was unable to move the flywheel anymore.

Inside of bell housing on driver side. Pressure plate touching bell housing.


Apparently these diaphragm pressure plates can be too big for C5TA-7505-B bell housings. I'm sure that to many of you this is a no-brainer, but it wasn't to me, so here's my advice:

If you install any new flywheel / clutch / pressure plate / bell housing combo, make sure you turn the engine by hand at least one full revolution to make sure that there is enough distance for everything to move freely.

As a result, today we're going to pull the bell housing back out, check the damage, see if we can grind or sand it down to a point where the pressure plate can move freely, and put everything back in again.

hth
 

Attachments

·
Registered
Joined
·
3,185 Posts
Holger, yeah, some of the bigger than 11" clutches don't fit every bell. But my guess would have been that there would be more room in the truck bell than in the others. Have you considered a Lakewood Bell ? What flywheel do you have ? The flywheel won't change clearance of course, but old cast bells make me nervous. SST should have told you to check, but they may have presumed you knew. Let us know if there is enough meat to grind or sand abit and then keep going. Lots of us would like to know. LSG
 

·
Registered
Joined
·
2,633 Posts
The problem is that is not the factory CJ bellhousing. It‘s a truck bellhousing, which may have helped the install since it’s deeper than the CJ bellhousing. If you got the trans modified for the FE, which means a shorter input shaft, You will need to check the engagement of the trans into the pilot bushing. If you got the trans with the standard input shaft all should be well with the exception of the pressure plate. I think you will have to go to an 11 inch clutch to fit that bellhousing....
 

·
Registered
Joined
·
2,633 Posts
I think I’d just grind away the offending areas in the bellhousing as long as the trans fits as it should. Finding a CJ bellhousing isn’t easy, but not difficult either. Not cheap though, and depending on the trans input shaft it might require a spacer.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #5
Hi everyone,

thank you for your insights on the C5TA-7505-B bell housing. Honestly, I didn't know that the this isn't a bell housing native to the CJ. I just assumed that it was, as it came with the block. I guess, one shouldn't assume things. By the way, the transmission came with the TRFP-TCKT5729A short input shaft kit for use of factory Ford 3 or 4 speed top loader style bell housings preinstalled.

Here's the update on what happened yesterday:

We pulled the bell housing and checked everything for damage. The pressure plate was ground down on the areas closest to the bell housing. The bell housing itself suffered several deep cuts on the driver side, specifically in the hump on top of the cut out for the clutch actuator.
755705

755706


So we applied an angle grinder to the bell housing and removed overall about an 1/8" in the area that was hit by the pressure plate. To get it right, we had to re-install the bell housing several times and check for clearance. Finally, we reached a little more than 3/32" minimum clearance with the bell housing installed.
755711


Here's a short video of the last clearance check: https://youtu.be/1FgZgdqQiR0

With that we put the transmission back in and did another few manual turns on the engine to check, if we are still good to go. Then we started the engine again ... ready to shut it down in a heartbeat if something went wrong. :oops: Thankfully, it started and ran smoothly. So we finally eased into the break-in procedure for the transmission, which went well.

After that we took the car for its first careful test ride after it was sitting on the lift for months! After 5-6 miles of really careful driving shifting became relatively smooth. Compared to the old top loader it's a blast. I hope this continues to get even better once I have a few hundred miles on it.

There are some things left to figure out before that, though:

1. Input shaft length: I still don't know if the C5TA-7505-B bell housing and the TRFP-TCKT5729A short input shaft of the transmission are a good fit. During the test drive we didn't experience any negative effects. However, I wouldn't want the input shaft to be too short due to the bell housing being deeper than an original CJ bell housing.

2. Transmission oil build-up: There was minimal oil build-up on the output side of the transmission, before we did our test run. Not sure, if I should be worried. After the test drive, I let the car sit over night and did not find any oil drops on the floor this morning.
755708


3. Starter pinion gear: We found an unfortunate other casualty to the whole pressure plate and bell housing clash. When the engine didn't turn anymore, the starter pinion gear suffered some injuries as well. I still don't know if I should change just the gear, or swap the whole starter.
755707


4. Clutch rattling: When the clutch pedal is fully depressed, a rattling sound starts to build up after a few seconds. It immediately vanishes when the clutch engages again. I still do not know why.
 

·
Registered
Joined
·
4,911 Posts
You may have damaged the pressure plate when it hit the bell housing, it may be distorted from the contact. I personally would replace the pressure plate and hopefully avoid a catastrophic failure.
 

·
Registered
Joined
·
95 Posts
I’m surprised it all pulled together the first time, pressure plate must have been in exact right position to not contact the bell housing.

I would be worried about the amount of material you ground off the pressure plate causing an imbalance at higher RPM and would consider replacing it.

Plus one on a scatter shield from Lakewood or someone. You only have one set of feet and this would protect you and your family if it ever came apart.
 

·
Registered
Joined
·
2,633 Posts
The only way to check the input shaft engagement is to install the trans without the clutch, nice thing about the FE bellhousing is that bottom cover, allows you to look up there, you’d be able to see how far the shaft engages in the pilot bushing/bearing.
 
1 - 8 of 8 Posts
Top