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77K5. The IronMaiden...9/2 headed for Blazer Bash 20!

jack of all trades build, overland, dunes, rocks, trails
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Pump pressure regulator is not up to snuff...only 150lbs line pressure, should have minimum 180, 200 would be great...so on to replacing the pump regulator.
I'm not sure why this wasn't a problem with the other valve body (Cheetah) it shifted great. This one is a TCI unit
 
I think I'm only running about 175 psi in my TH400, you shouldn't need two hundred, you don't have a 1000 hp drag motor.
 
TCI is telling him they need to see 200 for their valve body.
The Cheetah v/b worked fine on 150 line pressure. Stock is regulated down to 60-80 at idle in a 400, he is getting 150 at idle with the regulator valves I put in on the initial build.
He has been playing with the horseshoe shims in the pressure regulator valve in the pump to try and get 200, but not much luck so far.
He has changed shims/ valve assemblies in the regulator and either gets to low or way too high (300). He is going to try to get to it more today, and may change v/b back to the Cheetah if he can't get the pressure right for the TCI v/b.
 
Well be careful, 200 psi is getting up there, may shorten the life of the case lugs that hold the int clutch pack in if the shift is too quick at 200 psi. I would rather have a VB that works with the pressure you need than change the pressure to work with a VB made for much higher hp applications. You are using the band for engine braking right? If not I would put one of those case lug braces in for that pressure. $15 from kilgore.

http://www.kilgoretrans.com/html/new_stuff.html
 
Seems as though others are running the TCI v/b without issue, but that is what the TCI tech said it needed 180min -200 preferred.
it does have engine braking as well.
 
175 is about the norm for a high perf 400, going beyond that can induce pump wear, parts failures and even converter ballooning. Does the TCI full manual kit still leave the vacuum modulator in place or does it remove the modulator and substitute a plug of some sort? Does your pressure regulator system still use the stock spring or??
 
It has a plug in place of the vac modulator, and stock spring in the press reg.
 
I would change the spring in the pressure regulator and remove all but one horseshoe, I can send you a better spring if you don't have one. If that isn't enough I would remove the plug and install an adjustable small canister modulator and use the set screw to regulate the case valve tension.
 
Greg Ducato said:
I would change the spring in the pressure regulator and remove all but one horseshoe, I can send you a better spring if you don't have one. If that isn't enough I would remove the plug and install an adjustable small canister modulator and use the set screw to regulate the case valve tension.
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I know he has tried a different spring from a stock T400 he has in the shop, and different combos of the horseshoes as well, from none (100 psi) to one (150 psi) to two (300+ psi) . He wondered if valves were different and was going to compare those that he has with what I have in there now.

I just talked with TCI and they say up to 250psi isn't a problem and won't balloon the TCI torque convertor I have in it.

This adjustable canister will give more tunability to the pressure then?
Does it need a vaccum source or strictly a manual tuning piece?

thanks GREG!:bow:
 
The small red stripe modulator will allow you to pre load the valve in the case, no vacuum hook up required or wanted. If your builder has a PR spring from a TransGo kit that would bring the pressure up, either the yellow or orange spring with one or no horseshoe. I would be careful with the pressure despite what TCI has told you. 250 PSI in forward will give you way over 350 in reverse and that can be a problem in an extended high throttle reverse application.
 
Thank you Greg..when I talk with him I will mention these things...he did say with the 300+ it would bleed by the rings and put pressure on it while in reverse, effectively binding the trans up.
 
come on Kert, your just jealous of my success with TH400's!
So much so that you regret getting rid of that BOP 400/205 setup....I'm right, admit it!
 
76zimmer said:
come on Kert, your just jealous of my success with TH400's!
So much so that you regret getting rid of that BOP 400/205 setup....I'm right, admit it!
Click to expand...

I prefer the simple reliability of the manual transmission. Sorry Dave, you can play with that hocus pocus all you want.

That turbo 400 is gona have a hard life in your 7000 lbs. blazer, especially knowing how much you favor the gas pedal! I know it can be set up to take it, Just gona take some playing with things to get it all right.
 
cybrfire said:
I prefer the simple reliability of the manual transmission. Sorry Dave, you can play with that hocus pocus all you want.

That turbo 400 is gona have a hard life in your 7000 lbs. blazer, especially knowing how much you favor the gas pedal! I know it can be set up to take it, Just gona take some playing with things to get it all right.
Click to expand...
totally agree...I like being able to (when working right) shift up or down without loosing momentum, I will start the bottom of a dune hill in 2:1 range low gear, hit 2nd pretty quick...although it makes enough torque I could just as well start out in 2nd gear and it'll pull up the hills without downshifting, usually having enough momentum I need to let off the throttle so I don't have a John or Wade jump going over the top.
 
You'll get it Dave, no reason it should be doing what it is doing in the first place if it's right.
Why did you change VB though, wasn't the trans working great before the case broke?
 
everything was working great...the Cheetah v/b was a forward pattern, and I had him put in the TCI which is reverse pattern. Also this case is a diesel case which may be a contributing factor...
 
Not sure if there was any difference in the cases on the diesel vs. gas. I may be wrong. I used a TH400 from a diesel Blazer and the only difference I could find was not in the case, but the deeper fluid pan. Turns out though that all '85 TH400s had the deeper tranny fluid pan from the factory. Also it came with a 6 bolt torque converter. Good to know if you're actually using a diesel engine since they used a 6 bolt flywheel instead of a 3 bolt flywheel like the gas engines. The 6 bolt converter will bolt up to the 3 bolt flywheel however since 3 of the holes line up. Those are the only differences I could see, but I'm no transmission expert by any means.
 
Greg mentioned a bushing in the modulator valve passage is different which may contribute to the pressure issue I'm having...haven't been able to get in touch with my trans guy today...I want it back soon, so even if I have to live with the delayed 1-2 shift I will run it that way until I can dig into it deeper this winter.
 
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