'64 Dart 4 Speed Synchro Replace Mandatory Parts List?

[Duggie]

Hello All.

Still playing scratch and sniff around our three day new, 64 Dart. I need to pull the head for a bad exhaust valve and would like to repair the bad 1st and 2nd gear synchros while the head is at the machine shop (along with looking for why the clutch is oil soaked).

To expedite the process and because I'm feeling really lucky, I'd like to order the basic parts anyone with experience would replace when opening one of these 4 speed transmissions. What would you with experience replace as standard practice?

And have they always made these synchros out of expensiveisum? I haven't placed an order yet, but I'm hoping they are not made out of unobtanium too. Would I be acting as dumb as my wife dresses me if i were to try and save a buck, and look for used synchros?

I thought I'd learned a lot on this forum over the last four months while looking for this car. Geeze, I barely scratched the surface!

Thanks!!

 

[66fs]

Synchros are being reproduced, not too bad $. Get Jamie Passon's book on the A 833 4 speed. Get the seal and gasket kit, New countershaft, new bearings, small parts kit. Take it apart, clean everything, reassemble.

 

[Duggie]

Book ordered. Thank you!

 

[AJ/FormS]

To expedite the process and because I'm feeling really lucky, I'd like to order the basic parts anyone with experience would replace when opening one of these 4 speed transmissions. What would you with experience replace as standard practice?

Nothing except gaskets and not every time either.
If your pockets are deep you can order kits but I have been using the same parts for decades, including bearings and seals. And synchronizers by repointing, back-cutting, and shuffling brass around.
Those are killer-tough transmissions.
If you are on a time-table, you're in the wrong hobby,lol.

 

[Duggie]

If you are on a time-table, you're in the wrong hobby,lol.

No kidding huh? I'm a bit of a time junkie. Probably too many years being self employed. If I can take the valve job's down time and go through the tranny, fix a few oil leaks, and replace the oil soaked clutch, I'm back watching my wife in the cruise mode, and yucking it up. Repointing synchros? Are you suing a Dremel or modifying a chainsaw sharpener, or?

 

[TheGrateRonzini]

I had one of the synchro clips break on me before. Very straightforward process. The Passon book is worth every penny.

 

[Duggie]

I'm looking out the window for Amazon to deliver the book.

40+ years ago, I rebuilt the OD tranny in a '49 Studebaker President. Can't remember much more than I did it, and it was a 6 volt positive ground electrical system.

Glad to hear there are no inherent weak points that people replace when they open the trans up because they know its a matter of time before it goes bad.

 

[AJ/FormS]

Repointing synchros? Are you suing a Dremel or modifying a chainsaw sharpener, or?

I use a high-powered,high-speed, electric die-grinder, with tiny dremel-like cutting discs, that start out about 1.125 x 3/32
I probably spend less time repointing than back-cutting. On the coast-side of the sliders you will usually find 6 to 10 teeth that take the brunt of the deceleration forces. If the trans has been popping out of gear, then you will see the evidence on those teeth. That has to be fixed. The cure is to just cut that part of the teeth away, and then 6 to 10 other teeth will come on line.
Occasionally someone waits too long, and the drive-side shows similar damage, which I also repair, but being more precise, to not overload just a few teeth.
The clutching teeth have to be recut the same way.
After that, the brake-cones are straightened and polished, then I grind a bias on them do grab the brass in the upshift direction, except on low, I grind it on the downshift side.
After that, I fit the brass onto the input gear and line them up from best to worst. I put the highest sitting one on second, next is third, and then first. Fourth gets the left over cuz by the time you get to fourth, usually yur not in a hurry anymore,and if you are it's only once in a long while.
The second gear brass is the hardest working one. It always shows the most wear. I don't like to put new brass on it, cuz new brass is tricky; they rarely work right as delivered.
I modify all my 4-speeds for faster shifting at 7200. I only modify second and third, for use with 3.55s. This consists of cutting away every other clutching tooth and the first 1/8th to 3/16 of every other slider tooth. I also cut three broad shallow grooves in each brake surface,approximately equidistantly spaced around the circle.
None of this needs to be precision work, I'm pretty bush about it.
When you are done, you will be able to shift faster than the brass can at any rpm, but the brass will still work for driving around town . At 7200 it will shift so fast you sometimes can't find the shift tell-tales in the blackies.

As to the cluster-pins mine have 4 lives. I just cut new grooves for the keys as required and use both ends; it don't have to look pretty.

I tried real hard to use full synthetic oil, but it was too slippery, and shifted too slow; no matter what I did. I had the trans out 4 times in one week, trying different things, but nope,nothing worked.
So,in the end I went back to 50/50 Dextron II/75-90 dyno gearoil.
And we were back in action. All the mods worked with that 50/50 mix.
BTW, you probably don't need to shift yours at 7200,lol, but all the mods work just as good at any slower rpm,lol. Lightning I tell ya. And the brass will last for decades.
BTW-2
Only the low gear really needs the repointing, and it is easy to put too much bite on the brass, and then sometimes going from neutral to first with the car stopped, the teeth will butt and lock. Then you will have to put it in another gear to break the lock, before re-attempting first.
To not have this happen; firstly I try not to put too much bite on the first gear brake, and secondly I try to grab first before the car stops moving, and thirdly if already at a stop, I don't declutch and wait for the input gear to stop spinning; I just clutch, hesitate, and slam it in; Or I will clutch and put some pressure on the brake, but don't wait for the cluster to completely stop spinning. Just before it does, slam it in.You'll get the hang of it with practice.
I recommend not to use oil with 140 rating,I can't get that chit hot enough or thin enough, for fast shifting; 50/50 will work just fine.

 

[Duggie]

Geeze oh flip! I feel like I asked for a drink of water and got thrown in the lake. Ha!

I'm reading this more than once, and probably breaking out the crayons to help me keep up. Way cool work man.

 

[66fs]

You probably will not need to do anything to your trans like above. They are pretty stout even if abused.

 

[Duggie]

It's nice to know these transmissions are at the opposite end of the spectrum from, say a Force outboard motor. Your methods are till great food for thought. One of those thoughts is if 2nd gear is the most used, and new synchros can prove problematic, does it make sense to use the old synchros from 3rd and 4th (that engage fine) on 1st and 2nd and put new ones on 3rd and 4th? With this 245 rear end, 1st gear intersection turns are going to be the norm.

 

[66fs]

The synchros are not usually a problem. Just use 90 wt gear oil and you will be fine. With 2.45 gears you won't be a racer anyway, but it will be nice for highway cruising and mpg.

 

[Duggie]

Yep, for a base we wanted a driver that didn't need extensive body work. I was surprised to find such a tall rear end. I think we can live with it. If not, I'll do something about it after suspension and other driveline work to make it comfortably reliable.

I did put new 90 wt gear oil in the tranny and found no change in the 1st gear down shift and 2nd gear up / down shift grind. I gave a brief thought to the specialty gear oils, but decided to save the money.