Engine/Transmission (1994 - 1998) Auto input shaft ? - when needed?

[bluthndr]

How much power do you make before you break/broke one, and how were you using it when you did?



I am buying a bigger turbo and convertor (plus a few other goodies), and plan on coming to "rest" somewhere over 500hp...

 

[bmoeller]

Heading towards 500hp, huh? You'll need billet. Have heard of some input shafts breaking around 4-450 hp. Don't know what they were doing at the time.

 

[bluthndr]

Alright - so where can I get one (other than the obvious) and if/since the trans has to come most/all the way down, what should I replace (assuming all looks good) other than the band strut?

 

[sam616g]

If your going for about 500hp I would recommend doing the full rebuild and all billet shafts while you have it apart.

I wish I did the billet shafts when I did my trans. Now it's going to cost a large chunk of change to do them now. :{

 

[bluthndr]

I plan on doing it all myself, so the labor is irrelevant, but the parts cost I would like to put off a little while if possible. Big difference in just pulling it off the engine and sticking in the conv vs a complete tear down... About $2k if you include billet shafts...

 

[Lsfarm]

Breaking input shafts

I broke my stock input shaft at 50-55mph on the freeway on-ramp. I had an EZ and stage one injectors at that time. I would guess around 280-300hp. I ran over a rough chuck-hole or pavement divider and the back of the truck bounced in the air, when it came down bang! I was in neutral, or so it seemed. But it was the input shaft. A $200 towing bill later and two days lost income from work [serious $$-loss] I had a billet input shaft installed. Now I won't upgrade a trans without a billet input, thankfully this was my own trans and not a customers.



At the risk of sounding arrogant, if you have to ask what else to change once you are inside the transmission, then are you really sure you should be there? There is ALOT to correctly upgrade an automatic trans. Especially if you expect it to hold 500hp. 500hp on our engines means around 1000 ft/lbs of torque, and the stock internals just won't hold it. Sorry but that's the way it is.



There are several guys who have done their trans 'on-the-cheap' and have had to do them over again, and even again. If you want to get really good at R&R of your trans then I'd say go for it. You may be lucky and have a relativly good stock trans and with a few upgraded parts it may hold 300hp but 500hp?? not a chance in my opinion.



Just one example: in OD, there is the rear clutch, the third gear clutch pack, the OD clutches, and the TC's lockup clutch all needing to have good pressure applied, and enough surface area to hold the power you are putting through it. Any one of those four clutches can slip and they will if they are not improved during rebuild and upgrade. Just throwing a good converter at the trans only attends to one of the links in the chain, any one of the other links can be too weak and slip, smoke the clutch surfaces, contaminate the ATF, plug up the filter and cause low pressure everywhere, and then the whole trans is trashed. I've rebuilt this exact scenario several times. And to add insult to injury the new parts that were installed are contaminated with all the clutch material/burnt ATF and need to be refreshed or replaced, this costs more $$.



And with the above scenario, you have to take care of the many places where a stock transmission can leak pressure. The available pressure has to get to the clutch packs, and there are many areas where the stock trans leaks pressure internally. There is no easy or cheap way to make a trans hold 500hp/1000 ft/lbs tq .



If all you can afford right now is a new TC and a billet input then limit your hp to less than 300 or so, if you want any degree of reliability. Otherwise if the transmission is working OK right now, hold off on your HP upgrades and trans upgrade/rebuild untill you can afford to build the trans to hold what you want it to hold. It will cost a lot to go through the trans twice or three times.



Hope this helps, Greg L

 

[Partyat33]

Hey Greg, what about intermediate shafts and or output shafts. Aren't they also suspect ?

 

[Lsfarm]

Other Billet parts

The ouput shaft can break pretty easy if you are doing four-wheel launches at the dragstrip. Above 20 psi boost will usually snap the shaft when launching. The intermediate shaft is pretty hard to break, I think over 30 psi boost in 4x4 brake-torquing is needed to take out the intermediate shaft. That's a lot of torque!!



I've installed a lot of billet output shafts for the trucks which will be drag racing and sled pulling. And every trans gets a billet input shaft. Lots of other specialized parts in the trans too.



Dennis did you ever figure out your blow-by problems?? PM me with info.



Greg L

 

[Swamp Donkey]

I am also voting for the do it once do it right situation. I had my DTT transmission rebuilt by Bill K and he was standing there with the billet input shaft in his hands asking if i wanted it put in. I "cheaped" out and said no. I will now have to go back to Bill and get the input and output shafts installed eventualy. I knew better... ..... but I thought I would save a few bucks. It is going to cost me way more in the end.

 

[zstroken]

I always hear everyrun saying about how the leaks cause all sorts of problems, and I could see that there could be an issue if they do leak. What particular areas are checked for leaks? How are they fixed?

 

[justinp20012500]

#ad




If yours breaks like this you are lucky.



They usually strip the splines that are in the hub. It can take a front pump ($200) and a TC ($200-$1000)



I broke this one doing a locked shift when I was at 400 HP.

 

[bluthndr]

So - since the prices are all the same (+/- $50) do you want a billet shaft or a one piece forging (shaft/drum)?

 

[Lsfarm]

Not a one piece item

All the input shaft/hubs are two-piece, the shaft and hub are machined separately and pressed together. The factory ones are a cast steel and are brittle. The Hub often splits, the splines strip, or the shaft shears.



Personally I'd buy the DTT input shaft. Of course I'm biased towards DTT.



Edit: I see that someone is making a one piece shaft, I'll let the dragracing and sled pulliing guys test this new item, I wouldn't recommend it untill it has proven itself. I'm not sure how they machine the required oil passageway under the seal lip?? I'd like to see one, but I'm not going to buy one just to satsfy my curiosity.



The DTT input is taking everything anyone has put through it. In excess of 800hp /1500 TQ. that I know of.





Greg L.

 

[zstroken]

I hear that there is a one piece input shaft hub out now. Some place like supersonic or something like that. I just heard it from one guy can't confirm it though. Greg, I still am looking for some guidance on where to look for internal leaks? I have always heard people preach about this, but when you ask questions it appears to always be just a bunch of smoke and mirrors.

Thanks

 

[bluthndr]

That's what I thought too:



http://www.transmissioncenter.net/hardened_shafts_and_drums.htm



Go to the bottom and scroll back up about 3 screens. #7S.



No offense Greg, but it seems everytime I "talk" to a DTT tech I get the "are you sure you know what you're doing" intimidation thing - which I don't get elsewhere. I understand you're trying to promote your brand, and I have no question that DTT has/makes some good parts that solve problems, but some of the DTT affiliated do come off as, well, arrogant.



The funny thing is, that as long as I have been on this forum, no one will talk openly about what they broke and why. Everyone just breaks and then takes it to one of the big transmission shops and gets it gone through all the way. Even then, some break, but there is a warranty, so no one complains.



It is frustrating for me as a technician by trade to have the solution to a problem be "send it out for a $3000 rebuild because they have internal leaks and stuff. " Well, no %^#$ that fixes it, but it doesn't teach anyone anything about what SPECIFICALLY they get for their money over and above a basic rebuild. The whole reason I got into turbo diesels is that it's something new to try/learn at, and while there is great in depth info about engine/fuel/turbo setups, the answers on here to trans questions are sometimes lacking.



That said, I realize that there are many people that make their living off this stuff, but I am a tiny fraction of the market (an auto tech with tools, facilities, and knowledge to successfully repair auto transmissions is not too common on here I don't think), but the vast majority I think would gladly pay whatever just to not have to do it themselves - even if they do think they know how.



I guess I'm just frustrated with the total lack of knowledge here on this board about auto trannies - with the concensus being "throw $3000 at it and it will hold. " Like I said, the knowledge is worth something, but I think people ought to be able to get more info about what is done other than "add the DTT parts" for instance. I know I would never try cutting one of the (double) reliefs in those drums like you guys do, or have the time & skill to mill out an apply lever or servo...



On the other hand, I am not nice to my (sorta) stock trans and at 320 hp with 40" tires it still shifts very firm, and has for the last 2 years with that kind of power. Convertor clutch? Sure - I knew it was coming, I just put a cheap reman in it when I did the swap. It's tough to swallow that I "need" all these other parts when my trans has been perfect for 45,000 miles, 20,000 of which with mad diesel power - know what I mean? FWIW I do believe everyone that I will need shaft(s) when my trans comes out for the convertor after the turbo (and pump?) get done.



I agree 100% from a business standpoint that making it ALL bulletproof is best, but no one can tell anyone "this causes this, and this is how you fix it. " It's only "if you have any problem with your trans it needs everything. " Bill K (from his boards and experience) certainly knows his stuff, and I will eventually buy some parts from him, the "every diesel tans needs all the stuff all the time with some extras (shafts, drums, etc) sometimes" 'diagnostic' (I use the term loosely) approach by some of our professional trans people just doesn't work for me.



Enough ranting - can anyone give me a stock pressure # and a "good" pressure # off the test port so I at least know where I'm at?

 

[bluthndr]

I hear that there is a one piece input shaft hub out now. Some place like supersonic or something like that. I just heard it from one guy can't confirm it though. Greg, I still am looking for some guidance on where to look for internal leaks? I have always heard people preach about this, but when you ask questions it appears to always be just a bunch of smoke and mirrors.

Thanks

Exactly! No matter what, I will post some pressure #s off my truck and a few others in the next week or two. Anyone wanna get together in SW MI for a trans pressure party (dancing ##### not provided)?

 

[bluthndr]

Just one example: in OD, there is the rear clutch, the third gear clutch pack, the OD clutches, and the TC's lockup clutch all needing to have good pressure applied, and enough surface area to hold the power you are putting through it. Any one of those four clutches can slip and they will if they are not improved during rebuild and upgrade. Just throwing a good converter at the trans only attends to one of the links in the chain, any one of the other links can be too weak and slip, smoke the clutch surfaces, contaminate the ATF, plug up the filter and cause low pressure everywhere, and then the whole trans is trashed. I've rebuilt this exact scenario several times. And to add insult to injury the new parts that were installed are contaminated with all the clutch material/burnt ATF and need to be refreshed or replaced, this costs more $$.

I guess more than anything Greg, I am looking for the order of the fuses. I don't doubt that the reason my internal trans parts (& clutches) are fine is 'cause all my power just flashes the convertor to 2200+ when I hit it. I'm sure that will change somewhat after a convertor install.



I will be in your neck of the woods this weekend. Any chance I can check out your truck(s)?

 

[Lsfarm]

Education and Techniques.

Zstroken, bluthundr: there are certain items and techniques that DTT trains their techs in the use of, and we are asked to not to publish this info and knowledge on a public forum. Maybe some or all of this is known by the other transmission companies, but I doubt it. Much of it eventually gets public.



DTT spends a lot of money and time developing new parts, techniques, and identifying problems and solutions. This is a product of the background of knowledge and the volume of transmissions that go through DTT's shop. To publish these items and knowledge invites 'reverse engineering' opportunities for the competition.



The performance trans business is obviously very competitve, and DTT has seen a lot of techniques, tools and specific speciallty parts start to appear everywhere. I do my best to keep my customers informed with what I do to their transmissions, what their specific problems were in their transmission. However I don't attempt to train every customer to be a trans tech.



I understand the frustration you feel when you want to know these specific techniques, and how to cut corners on buying a similar product for less money from someone else. This is why I spent the money and time to travel to DTT's shop, and spend a week and get trained. I have an investment in my training, it is a business investment.



If you were to contact ANY of my trans customers you would find that I educate them pretty thoroughly on their transmission, I spend a lot of time with each customer if they have the time to spend. I feel they are paying for that when they buy DTT's products and my services. There are quite a few potential customers who have been to my shop, driven my trucks, and stood at the workbench while I showed them what would go into their transmission. I want my customers to know what they are paying for. But I don't know of any one of these people going out and doing their own transmission using the knowledge I shared.



The TDR is a great place to share experiences and suggestions on products or troubleshooting. And everyone wants to avoid the dealers. I applaud this sharing, I don't want to spend my money at the dealer either. And I don't want to pay some dealer tech three hours labor to discover something that I could have read about on the TDR and fixed in ten minutes. This is what started the TDR if I have the history correct.



Guys, check your PMs



Hope this makes sense, Greg L

 

[justinp20012500]

bluthndr,



I feel your pain...



I have done five transmission overhauls with a performance package that I have put together.



One has seen over 600HP for a little over 20k and is still new. (Tore it down last week to try a different stator combination)



What would you like to know????

 

[zstroken]

Thanks for the PM Greg. I can't believe you told me all of the DTT secrets so easily. I expected to have to bribe, or torture for them. Just kidding, like I said thanks for the input