1990 L98 Vette, auto. 383 with 202 valves and three angle valve job and a "teeny cam" (don't ask, don't even want to post about that again, but thought it might be relevant)

Ok so I had a 383 installed, within a couple thousand miles the transmission blew, I had it rebuilt, and within a couple hundred miles it blew again.

The second time the whole car went to the transmission shop and before they even had the transmission out of the car they called me to tell me that "the vacuum was set wrong" and that is what blew out the new transmission, and likely what blew up the old transmission.

The people who installed the engine are claiming that

"HE ALSO COMPLAINS THAT THE VACUUM "WAS SET WRONG", THIS WAS CAUSED BY AFTERMARKET ENGINE, IT DOES NOT HAVE THE SAME SETUP AS STOCK, A COMPLETELY DIFFERENT ENGINE. AS WE TOLD HIME FROM THE BEGINNING, THIS IS NOT RECOMMENDED FOR THE VEHICLE, BUT MR. BATES WAS INSISTENT AND WE OBLIGED. HIS "VACUUM" IS WRONG BECAUSE OF THE ENGINE HE INSISTED BE INSTALLED"

I pointed out that I had supplied them the original service manual and they should have been able to get the setting from there.

"MR BATES DID NOT PROVIDE THE SERVICE MANUAL UNTIL MONTHS AFTER ENGINE WAS INSTALLED.ALSO THE ORIGINAL SERVICE MANUAL WOULDN'T PROVIDE MUCH HELP HERE BECAUSE HE IS MODIFYING THE ORIGINAL SET-UP, THE MANUAL ONLY HAS REPAIRS FOR ORIGINAL EQUIPMENT. IT DOES NOT CONTAIN INFORMATION ON MODIFYING THE ENGINE INTERNALLY AND EXTERNALLY, NOR CONTAIN LANGUAGE FOR RETROFITTING ORIGINAL COMPONENTS ON AFTERMARKET PARTS.

It should be noted that They did the work in October, I supplied the manual in December, they didn't work on the car again until march, as it was winter in Michigan.


Any help here would be appreciated, I think this guy is trying to duck responsibility.

 

A 700r4 does not receive a vacuum signal. He is full of crap. There is a TV cable that must be set correctly or the transmission could die.

 

They are pulling your leg, find a new shop or have them explain in detail how a transmision without a vacuum modulator could be set wrong.

 

Transmission repair bill actually states "Throttle pressure settings way off causing transmission failure"

I was told by a different mechanic (not either of the two involved here that it was a vacuum issue. I assume that this other mechanic has never worked on this style of trans and just guessed based on a transmission style he was familiar with.

 

This could be likely. Did you set the TV cable after installing the tranny?

 

Like others have said, there is no vacuum setting on your transmission. They are clueless....

 

I did not set anything, it was set by the mechanic who installed the motor, and when I complained of it shifting badly he said "the computer needs to learn" of course I now know that the computer has nothing to do with it.

This whole thing has been an education and thanks to the fine folks here I know 30 times more about my car then the supposed high performance shop who did the install.

 

When you say "blow up" what do you mean? Is it free reving or....???

 

The only thing the computer controls on the transmission is the TCC (Torque Converter Clutch). Everything else is purely mechanical.

Adjusting the TV cable correctly is critical to the lifetime of a 700r4. It raises the transmission's internal pressure as the throttle is opened. If the pressure is too low the clutches will slip and burn up.

 

Get it done somewhere else and take them to court.
Someone didnt do their job.
"Mechanics".....sheesh. Makes you wonder.

 

Is trans not shifting correctly, slipping, noisey, fluid burnt? Automatics and modded TPI without new calibrations don't mix well. I have driven more than one as a clutchless 4spd (needed to winding it up a little) because of lack of gear in the back 2.59-3.08 along with stock calibration in ecm.

 

The first time it went out it shifted funny in into and out of 3rd and then it blew fluid out onto the motor and caught fire.

I had it rebuilt.

The second time it was just shifting sloppy, I took it to the trans shop and they told me it was junk because of the cable.

 

Who pulled the transmission the first time it blew? Whoever put it back in should have adjusted the cable. That is not just on corvettes but everything that uses a 700r4-4l60 transmission. But FWIW on a modified vehicle, good luck getting anyone to accept responsibility and pay. Just my opinion.

 

I'm not understanding how trans blew fluid out other than cooler line failure. You could try small claims court but the CYA disclaimer on invoice will hurt case. Who installed trans after rebuild? If the trans cooler wasn't cleaned out prior to rebuilt trans installation. Debris in cooler could be sent into trans causing it to fail....it happens...of course all of this doesn't fix you car. Find another shop or a recommended certified trans specialist who does side work. Then disassemble trans and find out what happenned.

 

All I know is after the fire the trans dipstick was partially dislodged, there was lubricant with a red tint sprayed on the inner fenders and the transmission was blown.


I am taking the mechanic to court, I was trying to figure out myself what went on (with the help of all you folks) so that I could go in there knowing what was what and not just relying on supposition.

I don't know if I will win any or all of my claims, but I at least will be able to speak in a knowledgeable manor and not let them blow smoke up my butt as they have in the past.

 

It seems you have 2 separate issues 1st engine. Why was trans overfilled to the point fluid came out top of tube; or if tube was not refastened allowing tube dislodge from trans causing fluid to leak. Unfortunately that should have been already resolved because of the resulting fire....who paided for those repairs? The trans issue would be with the shop who rebuilt trans. They had the car, knew what you had,They chose to to rebuild, install, and adjusted transmission. Road test car prior to releasing car to you. If your declined recommended upgrades if any they may have out. You will need a cause of failure for transmission shop. Just my thoughts

 

Who rebuilt it? A shop like Rossler Transmissions, for example or Aamco or something in between?

 

Vaccum has NOTHING !!! to do with this transmission, it is strictly CABLE! operated, DITCH THESE MORONS! These are the ones who give the transmission industery a bad name! Chuck Dublick www.countywidetransmissions.com They are either STUPID! or LIARS! do you want to deal with either type???

 

TV cable setting,as told before,is crucial here,you can blew your trans in just 500 miles or less if it is too soft becouse of low pressure that let your clutches slip and burn.TH700r4 it's only cable activated (ECM and the chip control only the lock up feature of converter)and not vacuum modulated as a TH 350 tranny.Vacuum here has nothing to do with your issue.All previous post are clear statement,and technically correct ,this is what your attorney letter must point at.I think responsability is of mechanic who installed trasmission on the car.He did the setting on TV cable.Usually transmission shops have a bench to test the unit after rebuild,it's a dyno for pressure testing everything.Who messed with your TV cable made it happen...