20+ years of "Building 904/727 for drag racing use"

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Duster346

Duster346

Chris Andrews
Joined
Nov 13, 2004
Messages
550
Reaction score
331
Location
Castle Rock, CO
I was one of the first members of this site when Adam started it in the early 2000's. I've been off this forum for the last decade or so, as life gets in the way of things we'd like to pursue further, unfortunately.

My quickest BB727 has been in the 7-teens at just under 200mph and my quickest SB727 has been in the 8.50's naturally aspirated at 6000 feet elevation. I am not here to win anyone over or make money. I don't need this site to make money-- however, feel free to let me know if you have any questions about your build. I've given free advice with no sales for several decades and I'm fine with it. I won't advertise my website, as that is against site rules now, but I've helped several on here with advice or parts for quite some time.

As always, good luck with your racing program!

Chris Andrews
Andrews Racing Transmissions
Castle Rock, CO

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WOW! Welcome back there stranger.
I remember the board when it was just a simple stack of messages.
 
Nice Challenger you have there. I'm about to rebuild the 727 in my cousins 66 Coronet 500. I may hit you up with a few questions. I've rebuilt a couple of 904's and they appear very similar. 65'
 
Chris, thanks for offering to help so many. It is nice to have someone that builds and races TF's to share experiences and provide a source for often hard-to-get TF race parts.
 
Chris graciously answered a bunch of dumb questions of mine without even mentioning that he owned and operated a transmission business or trying to sell me anything.

his technical expertise helped me avoid a potential problem and for that I'm thankful.

really nice guy and will most definitely get my biz down the line.
 
Duster346 said:
I was one of the first members of this site when Adam started it in the early 2000's. I've been off this forum for the last decade or so, as life gets in the way of things we'd like to pursue further, unfortunately.

My quickest BB727 has been in the 7-teens at just under 200mph and my quickest SB727 has been in the 8.50's naturally aspirated at 6000 feet elevation. I am not here to win anyone over or make money. I don't need this site to make money-- however, feel free to let me know if you have any questions about your build. I've given free advice with no sales for several decades and I'm fine with it. I won't advertise my website, as that is against site rules now, but I've helped several on here with advice or parts for quite some time.

As always, good luck with your racing program!

Chris Andrews
Andrews Racing Transmissions
Castle Rock, CO

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Hello Chris......I did want to pick your brain in regards to low/reverse band applied in 1st gear in a 727 transmission. I have two different 727 transmissions with reserve manual valve bodies and one have the low/reverse bands applied in 1st gear and the other does not. I am in the process of building a street strip 68 Dart with a 470 that should be around 600 hp and 600 tq. To be honest, I kind of like how the 727 without the low/band applied in 1st gear drives as there is no engine braking below 20 mph and I have made the mistake of accidentally down shifting the transmission with low/reverse band applied in 1st gear coming up to traffic lights on the street, which wasn't fun as it locked up the rear wheels. I have read the issues associated with not having the low/reverse band applied in 1st which is putting more strain on the sprag which can lead to failure. (At least that is what I have read). My question to you is, is there a way to safely have the low/reverse band not applied in 1st gear as to not have engine braking in 1st under 20 ish mph, or do I just need to deal with this type of operation so I can be safe with launching the car in 1st when I do go to the track. Thank you in advance for your insight!
 
Plymouth 65 said:
Nice Challenger you have there. I'm about to rebuild the 727 in my cousins 66 Coronet 500. I may hit you up with a few questions. I've rebuilt a couple of 904's and they appear very similar. 65'
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Thanks, it was a customer's car and was recently sold to one of the street outlaw fellas on television, and the combo is completely different now.
 
1967 Cuda said:
Hello Chris......I did want to pick your brain in regards to low/reverse band applied in 1st gear in a 727 transmission. I have two different 727 transmissions with reserve manual valve bodies and one have the low/reverse bands applied in 1st gear and the other does not. I am in the process of building a street strip 68 Dart with a 470 that should be around 600 hp and 600 tq. To be honest, I kind of like how the 727 without the low/band applied in 1st gear drives as there is no engine braking below 20 mph and I have made the mistake of accidentally down shifting the transmission with low/reverse band applied in 1st gear coming up to traffic lights on the street, which wasn't fun as it locked up the rear wheels. I have read the issues associated with not having the low/reverse band applied in 1st which is putting more strain on the sprag which can lead to failure. (At least that is what I have read). My question to you is, is there a way to safely have the low/reverse band not applied in 1st gear as to not have engine braking in 1st under 20 ish mph, or do I just need to deal with this type of operation so I can be safe with launching the car in 1st when I do go to the track. Thank you in advance for your insight!
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The safest scenario is to have the L/R band applied in 1st gear as to provide more sprag protection. You just have to make sure to not go into first gear at higher speeds.
 
Well howdy, yep, I remember you quite well , I for one used your input back in the day when Adam was running the show, happy to see you back and bringing even more knowledge to this site. Love my 8 1/4 heavy stack for my 360 street and fun times at the track, now in my 66 Plymouth Valiant you may know as Victoria.
Happy to see you have returned

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I was just browsing your web site over the weekend. One day I’ll upgrade my incredibly stockish 904 with some more robust parts. The only “jewlray” in this unit is the A&A spring pack and my Pro Trans brake. Eric D spoke pretty highly of your work. This one’s gone 9.0s at 148 so far :). Was sold a reinforced flex band, but am going back to a solid.

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…..and your 8.5 @ 6k feet build 727. Pro Flight style?
 
Thank you for coming back and participating in the forum and bestowing your knowledge on us!
I've rebuilt a 727 and a 904 with good success. Both of which I put trans go shift kits in along the way... For me it's mostly changing the clutch packs and the lip seals...
I'm on here all the time encouraging people to do the rebuild their shelves..
My question would be first a recommendation for a rebuild kit? Whether it be for mild or wild and why you would think so?
I say this because there's many more people on here that are not drag racing and I feel a lot of times that there really isn't nothing more special they need than just giving it a fresh rebuild..
And also if going a little more to the wild side in both transmissions what would be your first upgrades and why?.. maybe where a guy doesn't want to go full-blown race build but just add a few things in there that will add to longevity and good performance...
Thank you very much for your time as I know it's valuable...
 
A body said:
I was just browsing your web site over the weekend. One day I’ll upgrade my incredibly stockish 904 with some more robust parts. The only “jewlray” in this unit is the A&A spring pack and my Pro Trans brake. Eric D spoke pretty highly of your work. This one’s gone 9.0s at 148 so far :). Was sold a reinforced flex band, but am going back to a solid.

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I've read your posts on several forums for years. Your 904 looks happy, and an impressive timeslip as well!!


…..and your 8.5 @ 6k feet build 727. Pro Flight style?
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It's not. Its Eric's and just a SB727. He wanted to use his 904s with this car and I wouldn't let him .. lol. But yes, the advantage of a protrans/proflite type deal is the bigger 727 sprag with the lightweight 904 geartrain. It's been my experience that the stock 904 sprag does not like big tires and tire shake.
 
j par said:
Thank you for coming back and participating in the forum and bestowing your knowledge on us!
I've rebuilt a 727 and a 904 with good success. Both of which I put trans go shift kits in along the way... For me it's mostly changing the clutch packs and the lip seals...
I'm on here all the time encouraging people to do the rebuild their shelves..
My question would be first a recommendation for a rebuild kit? Whether it be for mild or wild and why you would think so?
I say this because there's many more people on here that are not drag racing and I feel a lot of times that there really isn't nothing more special they need than just giving it a fresh rebuild..
And also if going a little more to the wild side in both transmissions what would be your first upgrades and why?.. maybe where a guy doesn't want to go full-blown race build but just add a few things in there that will add to longevity and good performance...
Thank you very much for your time as I know it's valuable...
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As for a basic paper, rubber, ring and seal kit, the majority are made by transtec and work fine. As for clutch and band materials, and clutch counts, I'm more concerned with having enough line pressure to hold a clutch or a band in a certain application. We've used alto red racing clutches for decades in all of our race builds and I don't have any complaints. Raybestos GPZs are fairly new, and we use them in all of our diesel builds with a lot of success. There would be no reason not to use the GPZs in a street or race build, either. They work very well from what I've seen thus far. Steel plates, I use standard steel plates up to 1500hp. I don't really use or recommend Kolene steels, as I've never seen an advantage for the additional cost. Bands--we use a red lining in all of the transmissions we build. Again, line pressure is more important than clutch color, as people have used Borg Warner yellows, and have done just fine.

The biggest thing I'd focus on in both transmissions is having a good valve body and setting up the transmission for no overlap. This transmission inherently gets stuck in two gears at once on the 2-3 shift, and a lot of shift kits will amplify that. A very harsh shift is not a good shift, it is a bind or overlap. You want a quick, firm shift with no overlap on the 2-3 shift. We do a lot to overcome this.

Other than that, at our elevation (6000 feet) we install a lot of low gear sets in both 904 and 727 to get a heavier, lower powered car moving quicker, and to 60 ft quicker.
 
The 904 experiment started a little over a year ago. It was a unit Chuck Lofgren built for my dad in the late 90’s to go behind his 11 sec iron head mill. I basically tore it apart to look at it, threw some new clutches and steels at it, had a converter built for it (A500 pump gear…. getting hard to find) and ran it. I’m not looking to go faster but am more interested in investing in reliability. I know enough about torqueflights to be dangerous to myself ;) They are a very forgiving transmission.
 
Duster346 said:
The biggest thing I'd focus on in both transmissions is having a good valve body and setting up the transmission for no overlap. This transmission inherently gets stuck in two gears at once on the 2-3 shift, and a lot of shift kits will amplify that. A very harsh shift is not a good shift, it is a bind or overlap. You want a quick, firm shift with no overlap on the 2-3 shift. We do a lot to overcome this.
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What are some sure fire ways to minimize overlap?
 
You want to focus on getting the 2nd gear band off before the 3rd gear clutch pack comes on. This has a lot to do with 2nd gear apply lever ratio, 2nd gear apply servo and spring(s) and the number of high gear piston return springs.

On the flip side of overlap is shift flare, which is less common, but happens when the 2nd gear band comes off too soon well before the 3rd gear clutch is applied.
 
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Thanks for the service Chris…. I appreciate it. The servo showed up today. I also located an A&A shaft from a racer that had a spare. Some more insurance on keeping this trans alive

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There can be. I'd say up to 500hp naturally aspirated with a lighter car you'd be fine. I've built several.

However, the weak link will be the factory input shaft/forward drum. The input shaft can rip out of the drum.

There is not an upgraded input shaft/hub assembly for the A500, 42/44RH&RE transmissions available at this time.

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