does anyone run a CPT tranny?
05-17-2008, 05:53 PM
#21
Teching In
Join Date: Oct 2005
Location: Elkton, Md.
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I really hate to see threads like this. However after reading this thread there are somethings I would agree with and others that I do not. As builders we all have our own views of how things should be done and what has worked for us. Like stated above obviously this is the case here.
As for the comments on the new reverse input drum. I have been building these transmissions for a long time now and have seen many reasons to change or not to change. We have standards that we build by depending on level of the unit we are building and we stick to them. The reverse input drum obviously needs to be flat in order to have a good apply surface for the 2-4 band. We do replace many of them because they are not perfectly flat. In level 5 builds it is an automatic replacement idem. Also the area where the sun shell rides on this drum does get damaged with use. This causes clunks in second and forth and also adds to drive line slop IMO. I have even heard it produce noise on a dyno. Also on the inside of the drum where the apply cushion plate rides, I have seen this area worn badly. I have found in transmissions in general that in areas such as this, a weird apply can be felt, a delay or even a noise can be heard. I always replace this piece when seeing it. Also a very worn drum in this area allows the cushion to rub on the input drum creating metal. For the price of the drum to me it's a no brainer.
Moving on to the sleeved input drum. This piece can be a double edged sword so to speak. I will agree that there are pros and con's if not set up properly. In my early days of using this setup I found it to be a PITA and also a few failures that came with using it. I have greatly reduce all of them and have had great success in using it. The issue with this piece that most find is that you will need to run aluminum forward and overrun pistons. If a steel forward piston is used, overrun seals have been caused to blow out and fail. Now with using both aluminum pistons we run the risk of the forward piston breaking. I feel that most of these failures are cause by excessive forward clutch clearance and also pressure spikes in the unit. If the unit is set up properly the failure points are actually eliminated greatly. The main idea in using this style drum is to reinforce the spline area where the aluminum drum and the shaft are pressed together. I have seen the input shaft float in the drum causing a clutch failure in a non sleeved drum. Also when I sleeve a drum I fully remove the input shaft to see how tight it really is in the housing. You can see this by how easy it presses out. Also after installing a sleeve the shaft usually is much harder to reinstall it. That tells me the sleeve is doing it's job. IMO
As for the bearing style shell. I feel that it is a nice piece and a nice addition to any build. I recently had a nice conversation with Greg Nader from Sonnax about bearing style shells. (VERY SMART GUY IMO) Any time when a bearing can be used instead of a washer it is a good thing in any transmission when set up properly. With a 4l60e based unit the bearing inside the rear planet really takes the load of the shell and the reverse input drum. Obviously there are parts moving at great speeds and are getting loaded and unloaded very quickly when shifts take place. I have seen bearings in this planet fail over the years and always blamed end play. Not really understanding as to why until after talking with Greg and stacking up the parts to take a better look with him at the shop. The issue is with a bearing style shell the low roller race needs to be machined to the proper height to eliminate the load on the bearing in the rear planet. With that being said the bearing that is installed on the shell takes this load instead. The bearing that we use is a very large bearing that far exceeds the one used in the rear planet not only by size but in durability. And yes it comes from Sonnax. The sleeve that we press on the beast shell is really to retain the bearing. I have found that some times the sun gear has to be pressed into the sun shell after doing so. I guess anytime you reduce clearances it has to be a good thing. With that being said IMO it is a nice addition to our product. This shell is used in all level 4 and 5 builds.
As for the shift kit that is used in either build, that is builder preference. We are actually looking at using a kit that comes from sonnax. The trans go kit is a good kit and is very popular. We do modify it and use most of what comes in the sonnax kit already. So for us it really is a toss up. Both products have pros and cons but the key is to find the right balance when using them. The sonnax kit does not offer a gear command feature.
To the original poster, I wish you the best of luck in which ever direction you decide. CPT has many happy customers and I do know that Frank has built more than a couple units. Obviously we are more money but then again we do install many new parts and also the custom ones that we make or have made. I feel that our product is a very good piece and you could not go wrong with choosing either. Good luck, Vince.
As for the comments on the new reverse input drum. I have been building these transmissions for a long time now and have seen many reasons to change or not to change. We have standards that we build by depending on level of the unit we are building and we stick to them. The reverse input drum obviously needs to be flat in order to have a good apply surface for the 2-4 band. We do replace many of them because they are not perfectly flat. In level 5 builds it is an automatic replacement idem. Also the area where the sun shell rides on this drum does get damaged with use. This causes clunks in second and forth and also adds to drive line slop IMO. I have even heard it produce noise on a dyno. Also on the inside of the drum where the apply cushion plate rides, I have seen this area worn badly. I have found in transmissions in general that in areas such as this, a weird apply can be felt, a delay or even a noise can be heard. I always replace this piece when seeing it. Also a very worn drum in this area allows the cushion to rub on the input drum creating metal. For the price of the drum to me it's a no brainer.
Moving on to the sleeved input drum. This piece can be a double edged sword so to speak. I will agree that there are pros and con's if not set up properly. In my early days of using this setup I found it to be a PITA and also a few failures that came with using it. I have greatly reduce all of them and have had great success in using it. The issue with this piece that most find is that you will need to run aluminum forward and overrun pistons. If a steel forward piston is used, overrun seals have been caused to blow out and fail. Now with using both aluminum pistons we run the risk of the forward piston breaking. I feel that most of these failures are cause by excessive forward clutch clearance and also pressure spikes in the unit. If the unit is set up properly the failure points are actually eliminated greatly. The main idea in using this style drum is to reinforce the spline area where the aluminum drum and the shaft are pressed together. I have seen the input shaft float in the drum causing a clutch failure in a non sleeved drum. Also when I sleeve a drum I fully remove the input shaft to see how tight it really is in the housing. You can see this by how easy it presses out. Also after installing a sleeve the shaft usually is much harder to reinstall it. That tells me the sleeve is doing it's job. IMO
As for the bearing style shell. I feel that it is a nice piece and a nice addition to any build. I recently had a nice conversation with Greg Nader from Sonnax about bearing style shells. (VERY SMART GUY IMO) Any time when a bearing can be used instead of a washer it is a good thing in any transmission when set up properly. With a 4l60e based unit the bearing inside the rear planet really takes the load of the shell and the reverse input drum. Obviously there are parts moving at great speeds and are getting loaded and unloaded very quickly when shifts take place. I have seen bearings in this planet fail over the years and always blamed end play. Not really understanding as to why until after talking with Greg and stacking up the parts to take a better look with him at the shop. The issue is with a bearing style shell the low roller race needs to be machined to the proper height to eliminate the load on the bearing in the rear planet. With that being said the bearing that is installed on the shell takes this load instead. The bearing that we use is a very large bearing that far exceeds the one used in the rear planet not only by size but in durability. And yes it comes from Sonnax. The sleeve that we press on the beast shell is really to retain the bearing. I have found that some times the sun gear has to be pressed into the sun shell after doing so. I guess anytime you reduce clearances it has to be a good thing. With that being said IMO it is a nice addition to our product. This shell is used in all level 4 and 5 builds.
As for the shift kit that is used in either build, that is builder preference. We are actually looking at using a kit that comes from sonnax. The trans go kit is a good kit and is very popular. We do modify it and use most of what comes in the sonnax kit already. So for us it really is a toss up. Both products have pros and cons but the key is to find the right balance when using them. The sonnax kit does not offer a gear command feature.
To the original poster, I wish you the best of luck in which ever direction you decide. CPT has many happy customers and I do know that Frank has built more than a couple units. Obviously we are more money but then again we do install many new parts and also the custom ones that we make or have made. I feel that our product is a very good piece and you could not go wrong with choosing either. Good luck, Vince.
Very nicely explained. We have a few differences of opinion on some things, but I do respect you and your builds.
The only things I wanted to comment on are about the reverse housing and the sleeved drum. We do check all the areas you mentioned in your post in our reverse houings. We won't use them if they are worn in any area. Yes, we could use a new drum in every unit, but I don't want to jack up my prices by $135 a unit. We deal with reverse drums as a "hard part". This way, our customers only buy one IF they need one.
I'm not sure I agree with too much forward clearance causing the forward pistons to break. We see these broken in many units we get in. I've also had several break in some of our "Performance", and "Race" builds. That's why they're part of our "Pro Race" build. I set my forward clearance with either 1 or 2 .080" (Early 700R4) frictions to take up clearance. In 19 years of building these ( 15 for 4L60E's), I've only had 2 input drums break. I've seen many more forward pistons break. I've also had transmissions come in (built by others) that were sleeved, but yet blew the whole center out of the drum. Most drum failures were traced back to using a converter with multiple discs, or no lock-up damper.
Frank
CPT
05-18-2008, 07:51 AM
#22
I've dealt with both Pro Built Automatics (my 85 Z28), and CPT (my 00 TA). I haven't had a build problem on either transmission, but the customer service that Frank at CPT provided when I dealt with him is top notch. Just because a part isn't listed on CPT build sheet doesn't mean it isn't replaced. They are checked and replaced as necessary - IMO the way it should be. It keeps the cost WAY down, half of what others charge.
Frank, I think you should look into becoming a sponsor here! There's a lot of people that are looking for a 4L60E that can take some abuse and not cost several thousands of dollars.
And personally, I would stay away from sleeved input drums.
Frank, I think you should look into becoming a sponsor here! There's a lot of people that are looking for a 4L60E that can take some abuse and not cost several thousands of dollars.
And personally, I would stay away from sleeved input drums.
05-18-2008, 09:09 AM
#23
think weve all told frank to become a sponser on here...problem is i dont know if he could keep up with the demand...the price diff alone would have so many people going his way it would be insane...
anyways like i said ive had 3 years worth of frank trannys and havent had a problem...
anyways like i said ive had 3 years worth of frank trannys and havent had a problem...
