[DeTomaso] Steering rack adventures/ oil specs and tranny oil

Peter Kovacs peter-kovacs at sbcglobal.net
Wed Aug 6 01:46:49 EDT 2008


Similar to the Ford T-5s and WC T-5s running ATF. Normal use they worked fine. After a long run on the freeway at an inappropriate speed. I pulled over to put the top up and crunch, crunch crunch with every shift. Evidently the "no load" capability and the inability to cope with the heat generated from the overdrive fifth gear, cooked the bearings. I was told having Redline MTL instead of the ATF would have avoided the rebuild. So thats what went in the next one. No issues after that.
 
Peter Kovacs
Property Equity & Mortgage Mgmt
209 345-6708 
209 523-4919 fx



----- Original Message ----
From: "JDeRyke at aol.com" <JDeRyke at aol.com>
To: adin at frontier.net; detomaso at realbig.com
Sent: Tuesday, August 5, 2008 3:03:35 PM
Subject: Re: [DeTomaso] Steering rack adventures/ oil specs

In a message dated 8/4/08 6:11:11 PM, adin at frontier.net writes:


> What do we think of the new trend (ok, not so new) of specifying water thin 
> oil in transmissions?
> 
> Do we know more than the engineers?  If one were to use "better" (my term) 
> lubricant, will it void the warranty?
> 
Not a matter of knowing more; this was strictly a bean-counter move. In 1982, 
GM started adding ATF, a hydraulic oil with no load-carrying additives, to 4 
speed trannys. The zero-wt oil dropped the internal drag enough to raise GMs 
CAFE (corporate average fuel mileage) rating. And the few performance owners 
that fragged their trannys and differentials  were cheerfully warranty-replaced 
but didn't significantly affect The General's bottom line. I bought one of 
these with 12,000 lightly miles on it and 6 months later seized the tranny in 
2nd gear at an autocross. I drove across town with the gearstick in Neutral and 
on teardown, it took a torch and every bit of my 12-ton press to break the 
normally-rotating 2nd gear free of the mainshaft. 
I used to have phone numbers at some of the Detroit factories, so I called 
and asked what the idea was of running ATF in a std trans. The engineer that 
answered the phone at the Powertrain Division tried to tell me they're redone the 
internal clearances and metallurgy for ATF. As it turned out, the Z-28 trans 
was a Saginaw 4-speed; when I told him I'd mic-ed everything, found no 
differences so I repaired it with NOS gears from a 1966 Corvair Saginaw with 
"non-upgraded' gears and 90-wt gear lube, and  it ran just fine except cooler, there 
was no answer. The next time I tried calling (when the differential went out 
at 26,000 miles- 1 K out of warranty), the phone number had been changed.... At 
least three Nor-Cal Corvette owners also lost trannys and one diff until the 
news of the wrong lube got around.  
FWIW, I have now lost three (3.0) Chev posi differentials- 2 in brand new 
cars and one in the low mileage '82 Z-28. I am now convinced that GM cannot set 
up a posi differential; and the next new car I buy will NOT be a GM. 
As far as warranty goes, do you really want the thing fixed exactly like the 
one that broke? On the latest- Judy's '97 Z-28, I didn't even bother with the 
warranty. I took it to a performance shop to fix it right for $1000. The shop 
owner said they saw an awful lot of this stuff. FWIW- J DeRyke



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