727 Build for Mid-10s

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I started getting some parts in and will be putting this thing together very soon. Are there any modifications to the case you guys recommend? Vent relocation?

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I've also heard of some guys drilling an oiling hole for the sprag like this - below. Is there any merit in doing this?

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I started getting some parts in and will be putting this thing together very soon. Are there any modifications to the case you guys recommend? Vent relocation?

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I've also heard of some guys drilling an oiling hole for the sprag like this - below. Is there any merit in doing this?

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Some things for you to consider. Yes I would move the vent to the tail shaft. As was recommended in post #25 plug the vent in the pump. Are you sure you will never install a transbrake, because if you do, that calls for some mods as well. One of the reasons to plug the vent in the pump is that several transbrakes on the market
Require a small hole be drilled into the front drum or the front drum piston. If you drill into the drum, oil will spray out of this hole directly at the pump vent and you will indeed have a leaking trans if the pump vent is not plugged. Also current NHRA rules require a puke tank on the trans. I moved my vent to the tail shaft and drilled and tapped for a fitting and braided hose right into a puke tank mounted on the pan rail.
Not necessarily required, but I had a fabricator weld a bung on my case which I drilled and tapped for external pressure adjustment.
Again not required, I cut a notch in the bottom of the bell housing
For easier access to check or tighten the converter bolts.
Also you could add the transbrake electrical connector now even if you don't use it. It requires drilling and threading the case, so why not do it now. I also drilled the small hole to get more oil the the roller clutch. Does it help, I cannot say. On a 727 you should put in the better hd pump gears especially on a 727. Note the stock versus had pump gear differences.

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Some things for you to consider. Yes I would move the vent to the tail shaft. As was recommended in post #25 plug the vent in the pump. Are you sure you will never install a transbrake, because if you do, that calls for some mods as well. One of the reasons to plug the vent in the pump is that several transbrakes on the market
Require a small hole be drilled into the front drum or the front drum piston. If you drill into the drum, oil will spray out of this hole directly at the pump vent and you will indeed have a leaking trans if the pump vent is not plugged. Also current NHRA rules require a puke tank on the trans. I moved my vent to the tail shaft and drilled and tapped for a fitting and braided hose right into a puke tank mounted on the pan rail.
Not necessarily required, but I had a fabricator weld a bung on my case which I drilled and tapped for external pressure adjustment.
Again not required, I cut a notch in the bottom of the bell housing
For easier access to check or tighten the converter bolts.
Also you could add the transbrake electrical connector now even if you don't use it. It requires drilling and threading the case, so why not do it now. I also drilled the small hole to get more oil the the roller clutch. Does it help, I cannot say. On a 727 you should put in the better hd pump gears especially on a 727. Note the stock versus had pump gear differences.

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This is great info. Thank you! The notch in the bottom seem like a good idea.

Is that elbow fitting your vent? It seems low. How much fluid collect in your puke tank?
 
This is great info. Thank you! The notch in the bottom seem like a good idea.

Is that elbow fitting your vent? It seems low. How much fluid collect in your puke tank?
No the blue fitting is the oil cooler return line.
My vent is in the same place as the pic you posted or there abouts.
 
No the blue fitting is the oil cooler return line.
My vent is in the same place as the pic you posted or there abouts.

Thanks! Are the lugs on those pump gears wider than stock? I'd imagine it would require a modified converter hub?
 
Thanks! Are the lugs on those pump gears wider than stock? I'd imagine it would require a modified converter hub?
Yes they are wider, no special converter required. Also there is only a chamfer on 1 side of the gears so you have more surface area on the converter hub than stock.
 
John Cope does not drill a hole in the front drum. Nor does he plug pump vent and relocate it. So I didn’t bother on mine and it works fine. Kim
 
John Cope does not drill a hole in the front drum. Nor does he plug pump vent and relocate it. So I didn’t bother on mine and it works fine. Kim
Turbo action wants hole drilled, griner wants hole drilled, tranzact want hole drilled. NHRA wants a guarantee that you will not puke fluid on the track. Only way is to relocate the vent to the rear and plug the front. John cope now has a video on plumbing a puke can
From the rear vent. If you drill the hole in the piston, it will not spray at the pump. This is for modern transbrake only. Ihmo
 
Do you have a link??? It's not on his youtube channel: John at Cope Racing Transmissions


But did you leave the plastic vent baffle in place? That was my question.
Well off hand I cannot recall if the 904 has the plastic vent baffle like a 727. My point with the puke can is that even if you do not have any leakage out of the stock vent, there is no way to hook up a puke can at that location. NHRA wants there to be no way for fluid to leak out. John does not have a dedicated puke can video but he talks about how to hook one up in the video link that I posted.
 
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My understanding is that the drilled drum is recommended for transbrake applications, which this particular build isn't.
 
Question - I noticed the Belleville spring has this ridge in it like it made contact with the planetary assembly. Any idea what caused this? I'm assuming this should be replaced as well?

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Was the thrust button gone on the front of the output shaft or was the forward clutch clearance excessive?

The bronze output/input shaft thrust washer was still there. The forward clutch clearance was .045" and the play between the belleville spring and piston was .048". I'll probably end up getting a thicker apply piston from CRT to tighten up the play in the forward clutch hub.
 
Another question -

These are the two input shaft/hub assemblies I've got to choose from. The left one has a pretty pronounced groove cut into the splines (left arrow). After inspecting the clutch assembly, one of the clutches was completely burned and bare of any friction material. This overheated and warped the steel that was against it, which wore the groove in the hub.

The one on the right has nicer splines, but the shaft has some rust pitting, which I'd imagine would compromise the strength of the shaft.

Which one would you choose???

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My understanding is that the drilled drum is recommended for transbrake applications, which this particular build isn't.
In your original post you said you did not want to have to take this trans apart again. You also said this is a street and strip car.
In John Copes video he says some recommendations are common to both manual shift and some are just for a transbrake. As I said in post 77, if you are sure you will never want to run a brake, you can build for manual shift only. I just wanted you to be aware that if you do decide later that you want to run a brake, you will have to disassemble the trans to do specific transbrake mods.
As far as the vent, leakage or not, to comply with track rules, and ensure your own safety, a catch can is now required. You cannot hook it up to the factory front vent, transbrake or not. So you might as well move it now if you ever intend to go to the track. Imho
 
There was no way your forward clutch clearance was .045.
I can double check, but that's what I had last night when I put it back together the way it came apart (with all the old clutches and such).


John Cope talked about this in his video, but it was not clear.
This video explains it better.


Thanks. I've seen that video and assumed the excessive play in the assembly is what allowed the spring to contact the planetary assembly. I thought Cope's video explained it pretty clearly too. I'll most likely end up getting a thicker piston to tighten up that slop. It's odd that the older unit I have with the early belleville and thinner piston only has .025" slop, whereas the later unit I have with the later-style belleville and thicker piston has .048" slop. I guess production tolerances were all over the place.
 
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