What parts to build a 600hp 727?

Posted By: 440Jim

Re: What parts to build a 600hp 727? - 05/08/12 04:02 PM

You don't absolutely need a lot for 600hp in a 727.
But 50 yr old parts can fail, so if you have the money a few extras are risk reduction.

Number 1 item is a good valve body (Griner, A&A, CRT, etc)
For safety the aftermarket front drum (resists explosion after a sprag failure).
A few small cost items for piece of mind:
- Reinforced front band strut ~$25
- All new bushings and washers for the 1st build (refresh maybe not)
- Babbit converter bushing in the trans pump housing
- If you don't spend for the hardened pump gears, at least put new ones in (cheap)
- Billet rear servo and HD retainer (mrRandyj) *won't crack*
- That '67 front clutch piston will only take 10 springs, so you might want to upgrade to a later piston for more springs if the valve body and builder recommend it for shift timing. But filling it with 10 new springs may be fine.

A 727 can do 600 hp with very little changes. But some
things are nice to have for additional piece of mind or to assure a good part.

Below are some other options:

Quote:

If you are going to a trans brake, the trans must be modified for its use during the build, so now is the time to put it in.
For example, drilled oil pressure relief holes in the clutch, drilled case for the solenoid wire, relocated vent,
number of front clutch springs, etc.

I don't have any cook book list to give, but here is my 2-cents, consider all advice.

For the front band, don't use kevlar. I like the solid/ridgid band rather than the flex band. Red lining. The rear band isn't so critical, and the kevlar should last a life time if the trans works properly. Typically a trans brake likes 15 springs in the front clutch. Depending on the manual valve body selected, 12-15 springs.

- A good valve body (with a brake if applicable)
- Check everything for wear (pump rotors, drums, ring rubbing surfaces, etc.)
- Relocate the vent with a brake (plug the front vent)
- All new bushings (just do it now, any refresh maybe not)
- All new thrust washers (cheap insurance)
- Set clutch pack clearances for the application
ex/ 0.015" per front disc (0.060" for 4 discs, 0.075" for 5 discs)
ex/ 0.025"-0.035" rear with 4 discs
- Check sprag for wear, at a minimum new rollers and springs
- The best improvement would be with a 16 roller sprag like the A&A Ultimate or Coan Super Sprag
- 3.8 or 4.2 front band servo lever (see valve body instructions)
- Rigid/solid front band (IMO releases better than flex band)
- Reinforced front band strut (servo to band)
- Babbit converter bushing in the trans pump housing
- Pre-'71 "solid" front servo with 2 springs, or shim the newer oil cushioned servo so it is solid
- Shim the rear servo so the cushion spring is almost solid
- A billet rear servo with a stronger retainer and stiffer spring is good with low band apply. <see mrRandyj>

I like the oil passage enlargement mods (ported reaction shaft support between the rings, clutch retainer holes 5/32", 1/16" oil hole to the sprag).

-And an aluminum or aftermarket steel front drum is a safety consideration.

Attached picture 7197120-Front_clutch_pistons.jpg

Posted By: Hemi Allstate

Re: What parts to build a 600hp 727? - 09/26/21 03:24 PM

I came across this old thread while doing a search. This is where I am going, with putting my 470" stroker in my 68 road runner. The trans is stock OE to the car and was freshened 25 to 30 years ago, and at that time the shift firmness was improved. Unfortunately the guy that did the work has passed on now, so I am not able to confirm how that was achieved.
We want to keep it automatic shifting, and will probably not be racing it due to concerns of body twisting .
I am thinking I will buy a billet front drum for safety. What other parts should I consider for the automatic version ? Is a bolt in sprag / orc needed ?
I noticed most folks used a RMVB and I do not want to go that route.
Also planning to use the original torque converter. Any ideas as to how that will respond to 620 lbs. ft. torque ? It makes that at 3500 rpm.
There are trans companies like TCI that have 727s rated for 850 hp and no mention of billet front drums ! That sounds like a dangerous path to me. Am I wrong ?
Thanks,

Mark

Posted By: moparx

Re: What parts to build a 600hp 727? - 09/26/21 04:16 PM

if a reverse pattern is out of the question, a trans-go TF2 kit will allow it to automatically shift in drive, but allow full manual when needed.
if a full manual valve body is wanted, trans-go and b&m offer full manual, forward pattern shift kits.
as to the bolt in sprag, i have been under the impression those were not really necessary unless the sprag race is loose in the case.

also, i seem to remember if going to change the sprag, there was an article about using the sprag from a C-6 transmission, as it has more elements. however, i have not been able to find that article, nor able to find anyone to confirm or deny my foggy memory of this.
a new drum is always good, but i remember mr. P-body claiming for years if a guy worked the transmission correctly, that would prevent over-speeding the drum. so i don't know.

Posted By: Cab_Burge

Re: What parts to build a 600hp 727? - 09/26/21 09:43 PM

What are your feet and legs worth?
Buy a good front drum now and use it

I say this based on you not knowing how much abuse the current front drum has been through

Posted By: Hemi Allstate

Re: What parts to build a 600hp 727? - 09/26/21 10:03 PM

[quote=moparx]if a reverse pattern is out of the question, a trans-go TF2 kit will allow it to automatically shift in drive, but allow full manual when needed.

I really want to stick with automatic shift , so the TF2 will work fine.
Thanks

Mark

Posted By: Hemi Allstate

Re: What parts to build a 600hp 727? - 09/26/21 10:21 PM

Originally Posted by Cab_Burge

What are your feet and legs worth?
Buy a good front drum now and use it

I say this based on you not knowing how much abuse the current front drum has been through

Cab, I really think this has had minimal abuse, since it was my mother's car since new. I never abused it as far as burnouts etc. , and I don't think my sisters did either. That said, I was going to spring for the billet steel drum for safety sake, since they may want to drive the car again when I get it finished. I want it to be safe. Cope sells a loaded steel drum all set up with clutches and steels and I thought I would have a local shop install the parts.
Is there anything else that I should do for upgrades?
I have a full manual 727 in my Allstate that I had CRT build with ultimate sprag and billet front drum etc. So I do value my feet and legs pretty high in $.

I was surprised that the 727 sold by B&M and TCI said nothing about the front drum.
Thanks

Mark

Posted By: jwb123

Re: What parts to build a 600hp 727? - 09/26/21 11:01 PM

Originally Posted by 440Jim

Quote

If you are going to a trans brake, the trans must be modified for its use during the build, so now is the time to put it in.
For example, drilled oil pressure relief holes in the clutch, drilled case for the solenoid wire, relocated vent,
number of front clutch springs, etc.

I don't have any cook book list to give, but here is my 2-cents, consider all advice.

For the front band, don't use kevlar. I like the solid/ridgid band rather than the flex band. Red lining. The rear band isn't so critical, and the kevlar should last a life time if the trans works properly. Typically a trans brake likes 15 springs in the front clutch. Depending on the manual valve body selected, 12-15 springs.

- A good valve body (with a brake if applicable)
- Check everything for wear (pump rotors, drums, ring rubbing surfaces, etc.)
- Relocate the vent with a brake (plug the front vent)
- All new bushings (just do it now, any refresh maybe not)
- All new thrust washers (cheap insurance)
- Set clutch pack clearances for the application
ex/ 0.015" per front disc (0.060" for 4 discs, 0.075" for 5 discs)
ex/ 0.025"-0.035" rear with 4 discs
- Check sprag for wear, at a minimum new rollers and springs
- The best improvement would be with a 16 roller sprag like the A&A Ultimate or Coan Super Sprag
- 3.8 or 4.2 front band servo lever (see valve body instructions)
- Rigid/solid front band (IMO releases better than flex band)
- Reinforced front band strut (servo to band)
- Babbit converter bushing in the trans pump housing
- Pre-'71 "solid" front servo with 2 springs, or shim the newer oil cushioned servo so it is solid
- Shim the rear servo so the cushion spring is almost solid
- A billet rear servo with a stronger retainer and stiffer spring is good with low band apply. <see mrRandyj>

I like the oil passage enlargement mods (ported reaction shaft support between the rings, clutch retainer holes 5/32", 1/16" oil hole to the sprag).

-And an aluminum or aftermarket steel front drum is a safety consideration.

I run the same basic combination as this post, it holds 800HP for several years no problems.

Posted By: Hemi Allstate

Re: What parts to build a 600hp 727? - 09/27/21 12:07 AM

;

I run the same basic combination as this post, it holds 800HP for several years no problems. [/quote]

Thanks for your input.

I will make a shopping list .

Mark

Posted By: 451Mopar

Re: What parts to build a 600hp 727? - 09/28/21 02:59 PM

One issue if it is a 1967 model. This could have an early course 19-spline input shaft, or the later fine 24-spline? (I think it is 24?) input shaft.
The pump stator supports are different too for the different input shafts, and all the pre-1971 transmissions used a different front drum with a narrow bushing.
I think all the aftermarket drums are the '71 and up wide bushing version. I don't know of an aftermarket drum for the earlier version with the narrow bushing, but I haven't looked for one either in the last 10 years.

What I am getting at is it might be easier and cheaper to start with a '71 up transmission.

The stock transmission with a good rebuild and TF-2 shift kit can withstand around 600 HP in a light car, or one that dosen't hook hard.
Above that the aluminum front planetary gear might fail from the shaft splines breaking in the aluminum gear body.

For safety, it is common to install a billet front drum (which usually allows 5 front clutches too), and a bolt in "Super Sprag" that has more rollers than the stock sprag.

The TF-2 kit will have you modify the rear band servo, has a new front band strut. I don't recall if the accumalator is blocked or uses a different spring (different shift kits / years have used both?)
I don't use the forward restrictor plug that comes in the shift kit.

The Alto red clutches and kolene steels are commonly used, but about twice the cost of Raybestos high-energy clutches which are also good.

Posted By: A727Tflite

Re: What parts to build a 600hp 727? - 09/28/21 03:11 PM

Originally Posted by 451Mopar

1967 Model Year got the regular fine spline, 1966 and earlier was the course spline.

Posted By: 440Jim

Re: What parts to build a 600hp 727? - 09/28/21 04:32 PM

Originally Posted by Transman

1967 Model Year got the regular fine spline, 1966 and earlier was the course spline.

Yup.

Posted By: J_BODY

Re: What parts to build a 600hp 727? - 09/30/21 02:10 PM

I wouldn’t run a 727 on the track without a billet front drum…. You do what you want

Btw my 90% stock 904 is at 72 passes and still alive! Low 9’s

Posted By: 451Mopar

Re: What parts to build a 600hp 727? - 10/01/21 01:07 PM

Originally Posted by Transman

1967 Model Year got the regular fine spline, 1966 and earlier was the course spline.

I owned a 1967 Coronet that was all original. It had the 1966 style input shaft much to my surprise. As I mentioned, '67 was a switch over year, so it could be either version.

Posted By: Cab_Burge

Re: What parts to build a 600hp 727? - 10/01/21 05:43 PM

Originally Posted by 451Mopar

Originally Posted by Transman

1967 Model Year got the regular fine spline, 1966 and earlier was the course spline.

I owned a 1967 Coronet that was all original. It had the 1966 style input shaft much to my surprise. As I mentioned, '67 was a switch over year, so it could be either version.

Posted By: A727Tflite

Re: What parts to build a 600hp 727? - 10/01/21 10:29 PM

Originally Posted by 451Mopar

Originally Posted by Transman

1967 Model Year got the regular fine spline, 1966 and earlier was the course spline.

I owned a 1967 Coronet that was all original. It had the 1966 style input shaft much to my surprise. As I mentioned, '67 was a switch over year, so it could be either version.

I doubt it was built that way on the line.

All the part numbers for the converters and transmissions changed for 1967.

Fact. The vehicle assembly plants work off of part numbers.
Fact. The start of a new model year has the plants purging previous model year assemblies from inventory.

In order for you to have a 1967 with a 1966 trans AND converter would mean they didn’t purge inventory of transmissions AND engines.
In 1967 converters were shipped on the back of the engine.

And trust me, if the converter doesn’t engage the trans both go back to the manufacturing plants with demerits.

Only reasonable explanation is the car went to heavy in-plant repair and someone stuck a leftover 1966 trans and converter in it, but it didn’t go down the line like that.

Posted By: gregsdart

Re: What parts to build a 600hp 727? - 10/04/21 02:58 AM

Originally Posted by dvw

Stock Rabestoes clutches,and bands. 4plates in the high drum. Turbo action manual V.B. ,3.8-4.2 lever. 3 pinion stock planets. These parts have gone 10.0-11.0 in my cars for thousands of passes w/o any failure.
Doug

On the three pinion planet, I agree Doug. The only failures I had was from Dana center that slipped on the tubes. How it ran for several runs With about 30 degrees of pinion angle I will never know. This last rebuild I did upgrade everything but shafts.

What parts to build a 600hp 727?