That's absolutely correct. The pump mod is just very cheap insurance.
Trust bearing !!!
- Thread starter GN280CI
- Start date
That's absolutely correct. The pump mod is just very cheap insurance.
Don showed me the light about the pressure too. Unfortunately I had already killed 2 billet cranks and $ out of my wallet plus not to mention the missed races and down time! Since I did what he said I've had ZERO thrust bearing problems( about 150 runs so far ), before it would wipe out a bearing in as little as THREE runs ( yes 3! ). My advice to you is do EXACTLY as Don says and don't waste time doing anything else.
Good luck
Dave Fiscus
Good luck
Dave Fiscus
cranks
I must be lucky. i have had stage engines and 400 trans for 10 years and so far i have never had any problems, i build my own trans, my pump is stock, pressure at the pressure port is 200psi, trans, brake applied it is 185, i buy drums, clutches etc, from coan, my fresh oncenter engine may pop the first hard run next saturday, good luck, oc,
I must be lucky. i have had stage engines and 400 trans for 10 years and so far i have never had any problems, i build my own trans, my pump is stock, pressure at the pressure port is 200psi, trans, brake applied it is 185, i buy drums, clutches etc, from coan, my fresh oncenter engine may pop the first hard run next saturday, good luck, oc,
You have to look at this pump mod from the point of a business owner that wants to keep people from going through a very stressful situation. It is not a pretty thing to have a crank thrust go out on an expensive engine. If you're building several 400s that will go into customer's cars, do you cross your fingers and hope none of them are crank killers? Do you install each 400 and perform time consuming cooler system pressure tests to ensure that you didn't just install a crank killer? Or do you just perform the mod to each and every 400 you build to make sure that if a crank thrust does go out, it wasn't because of the transmission.
The majority of 400s will go through their life controlling T/C pressure just fine. Racing mods or not. I have to say though, that if I just put 25,000+ dollars into building my Buick V6 with that brand new, beautiful billet crankshaft, I sure as hell don't want to even take the slightest chance that I'd be installing a crank killer 400 behind my engine. But maybe, that's just me.
It hurts absolutely nothing to do the mod, except to prevent the POSSIBILITY of hurting your engine by not doing it. Why worry about it. Just do the mod.
As I said before. It is very cheap insurance against taking out $25,000.00+ of prime machinery. It's just plain silly to me for someone to fooh fooh this advice. Live and learn, I guess.
The majority of 400s will go through their life controlling T/C pressure just fine. Racing mods or not. I have to say though, that if I just put 25,000+ dollars into building my Buick V6 with that brand new, beautiful billet crankshaft, I sure as hell don't want to even take the slightest chance that I'd be installing a crank killer 400 behind my engine. But maybe, that's just me.
It hurts absolutely nothing to do the mod, except to prevent the POSSIBILITY of hurting your engine by not doing it. Why worry about it. Just do the mod.
As I said before. It is very cheap insurance against taking out $25,000.00+ of prime machinery. It's just plain silly to me for someone to fooh fooh this advice. Live and learn, I guess.
Let me tell you what I've seen through the years. The Turbo 400 is the only transmission that has a reputation for taking out crank thrusts. When someone comes to me to tell me that their crank thrust was taken out, the first thing I ask is what engine and transmission. If it's not a 400 then I tell the fella there's a very good possibility that there was a problem with the assembly of the engine. Of course the engine guy is blaming the transmission, mainly because of all the stories about 400s taking out crank thrusts. You see, the crank thrust problems with 400s has given the engine guys an easy way out. Now, according to the engine guys, all transmissions can now cause crank thrust problems. Convenient for the engine guys, isn't it.
Now if the fella answered that the engine was in front of a 400, the next thing I ask is, "Do you know if a pump mod to control T/C pressure was done?" If the fella doesn't know, or if he brings me the pump to check for him and the mod was not done, this guy is ****e out of luck. The engine guy has a leg to stand on with his argument and the trans guy does also. The only way to know now would be to put the trans on a dyno and check cooler line pressure. The other choice would be to install the trans behind another fresh engine and check cooler line pressure or just cross the magic fingers. Who in their right mind would want to test this possible crank killer behind an engine that you're supposed to be breaking in with low loads? But, that's how some people think. Makes me pull my hair out.
I've seen that blaming game between engine and trans guys more than I care to admit. Boy. Could I tell you some stories.
Now if the fella answered that the engine was in front of a 400, the next thing I ask is, "Do you know if a pump mod to control T/C pressure was done?" If the fella doesn't know, or if he brings me the pump to check for him and the mod was not done, this guy is ****e out of luck. The engine guy has a leg to stand on with his argument and the trans guy does also. The only way to know now would be to put the trans on a dyno and check cooler line pressure. The other choice would be to install the trans behind another fresh engine and check cooler line pressure or just cross the magic fingers. Who in their right mind would want to test this possible crank killer behind an engine that you're supposed to be breaking in with low loads? But, that's how some people think. Makes me pull my hair out.
I've seen that blaming game between engine and trans guys more than I care to admit. Boy. Could I tell you some stories.
Never seen a problem with a T-350 over charging the T/C. As I stated in an earlier post, the T-400 is the only trans that has a testable problem to my knowledge.
trust bearings,
DON, i dont know you. and you dont know me. but what you were saying about the line pressure in 400. trans, i got to thinking about what you said so i installed a guage in the cooler line and cold idle at 1000 rpm pressure was 90 psi, hot 160 degrees, it was 60 psi at 1000 rpm at 2000 rpm it was 75 psi, after 2000 rpm the pressure never changed, trans, brake applied pressure dropped to down to 45 or 50 psi i only took it to 5 # boost , i tried another guage and they were within 5 psi of each other, the pump was in a trans. that i bought so when i inspected it for wear i never looked at the orfice, that was 4 or 5 years ago, after 70, 80, runs or ever winter if it last that long i rebuilt it, replace anything that is worn, seals,clutches,etc, that is all that i know how to do to them, now i will try to rember to check the pressure on my spare trans, if i ever use it, i have serval bop, and chev,cases and gobs of stock trans, parts that i need to get rid of, thanks for the info,
DON, i dont know you. and you dont know me. but what you were saying about the line pressure in 400. trans, i got to thinking about what you said so i installed a guage in the cooler line and cold idle at 1000 rpm pressure was 90 psi, hot 160 degrees, it was 60 psi at 1000 rpm at 2000 rpm it was 75 psi, after 2000 rpm the pressure never changed, trans, brake applied pressure dropped to down to 45 or 50 psi i only took it to 5 # boost , i tried another guage and they were within 5 psi of each other, the pump was in a trans. that i bought so when i inspected it for wear i never looked at the orfice, that was 4 or 5 years ago, after 70, 80, runs or ever winter if it last that long i rebuilt it, replace anything that is worn, seals,clutches,etc, that is all that i know how to do to them, now i will try to rember to check the pressure on my spare trans, if i ever use it, i have serval bop, and chev,cases and gobs of stock trans, parts that i need to get rid of, thanks for the info,
Experience always speaks louder than words. Unfortunately, experience can cost you plenty in this instance. I don't care how long you've been running the car like that, if that car were mine, knowing what I know and the experience behind it, and I had just done that test, I would have looked like the super hero Flash getting to that key to shut the engine down. I really don't care that you've gotten away with that pressure this long. That is just plain undue load on that crank thrust. Correct the problem!
turbodave231
Moderator
- Joined
- May 24, 2001
Don,
Would you mind posting a picture of the pump modification? I plan on going through and refreshing my T-400 in the future and I'd like to be able to identify the modification if it has been done or performing the modification if it has not been done.
No current issues with thrust bearings or trans, but you are right.....better safe than sorry!
Thanks,
Dave
Would you mind posting a picture of the pump modification? I plan on going through and refreshing my T-400 in the future and I'd like to be able to identify the modification if it has been done or performing the modification if it has not been done.
No current issues with thrust bearings or trans, but you are right.....better safe than sorry!
Thanks,
Dave
I'm sure I've already posted a picture. Check past posts using crank thrust failures as a search phrase. I know I've sent a pic out. Can't remember now if it was private or for a post. If you can't find it, let me know.
'BETTER SAFE THAN SORRY' is the right thinking in this matter.
Robert Wilson
Member
- Joined
- May 26, 2001
found the picture!!
See the link for a picture of the pump mod
http://www.turbobuick.com/forums/tr...urbo-400-pump-converter-feed-restriction.html
See the link for a picture of the pump mod
http://www.turbobuick.com/forums/tr...urbo-400-pump-converter-feed-restriction.html
Presently I have a JW TRANSMISSION I do not know if the company makes this modification???
Norbs, I whole heartedly agree with you. I see no reason to tempt fate. When the norm in the transmission industry is 40 psi, I guarantee you no one can come up with a reasonable explanation why running over 40 psi is better for the engine or transmission.
I personally know of no other shop that does the pump mod. I have only come across one other transmission that had the mod when I took it apart. Don't know who built it, but obviously he figured it out too.
If you have a 400, don't assume that shop did the mod. Even if they tell you they did. I've heard of people that went back to their tranny guy and asked if the mod was done and got a, "Ah, oh sure. We did it." It wasn't done. What a putts. Do the pressure test. If it's over 40, pull the trans and check it. Most 400s will test fine, even without the mod. If you have one of those, don't worry. Keep running it.
Personally, the 400 in my car and every 400 I build for customers, no matter what the application, gets the mod. I don't care if it's a crank killer or not, and I surely don't want me or the customer finding out the hard way that it is.
I can rest comfortably that my beautiful Moldex billet crank in my beautiful TA aluminum block will not be taken out by a crank killer 400.
The passage needs to be 7/64".
That's right Carl. I do believe Chris also restricts the feed. He uses a larger orifice than I do if I recall correctly. Thanks for bringing that up. I forgot about that.
The important thing is to control the pressure to a reasonable level. I suggest 40 psi and a 7/64" orifice has done that for me for 20 years. If someone wants to try a different size, go for it and good luck. I've even gone smaller with the size with no ill effects. I just chose 7/64" because it did the job.
The important thing is to control the pressure to a reasonable level. I suggest 40 psi and a 7/64" orifice has done that for me for 20 years. If someone wants to try a different size, go for it and good luck. I've even gone smaller with the size with no ill effects. I just chose 7/64" because it did the job.
