Hi
It's been a while but seem to remember around 1800 @ 130 kph in France last year on their nice motorways. Not really done a lot this year
I know I was getting 28mpg average for the 2 weeks I was there.
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| General servicing re the auto gearbox in a Z28 http://classiccamaroclub.mfatw.com/viewtopic.php?f=6&t=2615 |
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| Author: | SR-71 Blackbird [Wed Nov 28, 2012 8:12 pm ] |
| Post subject: | General servicing re the auto gearbox in a Z28 |
Hi all, I have the auto box in my Z28 and I wondered if anyone could explain the service/maintenance schedule regarding these please? Also out of interest does anyone know what their revs are at a steady 70mph on the flat with an autobox in D with overdrive? Thanks Alex |
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| Author: | Arizona [Thu Nov 29, 2012 8:13 am ] |
| Post subject: | Re: General servicing re the auto gearbox in a Z28 |
Hi It's been a while but seem to remember around 1800 @ 130 kph in France last year on their nice motorways. Not really done a lot this year I know I was getting 28mpg average for the 2 weeks I was there.
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| Author: | SR-71 Blackbird [Thu Nov 29, 2012 9:11 pm ] |
| Post subject: | Re: General servicing re the auto gearbox in a Z28 |
Mine is around 2400rpm at 70mph with an autobox in D overdrive, seems a bit high. Anyone else with an autobox care to comment? |
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| Author: | z28stu [Thu Nov 29, 2012 10:06 pm ] |
| Post subject: | Re: General servicing re the auto gearbox in a Z28 |
Hi SR-71 Blackbird Dont take this as gospel as i havent driven mine for a couple of months But i think at 70mph mines around 1500rpm and 90 its 2000rpm I may get a chance to drive it again before putting it to bed for winter |
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| Author: | SR-71 Blackbird [Thu Nov 29, 2012 11:24 pm ] |
| Post subject: | Re: General servicing re the auto gearbox in a Z28 |
Hmmm mine seems very high then, Can anyone suggest anything? Thanks |
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| Author: | chevy-stu [Fri Nov 30, 2012 1:10 am ] |
| Post subject: | Re: General servicing re the auto gearbox in a Z28 |
Surely you need to know the rear end gearing/tyre size to compare ... |
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| Author: | maudyZ28 [Fri Nov 30, 2012 8:49 am ] |
| Post subject: | Re: General servicing re the auto gearbox in a Z28 |
indeed it depends on the rear diff, ok so with a code GU2 this is a 2.73 ratio diff so at 70 mph you will be around 1600-1700 rpm ish if you have a GU5 this means you have the optional extra of a 3.23 gear ratio, i.e. better acceleration etc which should see you at about an 18% increase in rpms upto about 2000 rpm at 70 mph.I have installed the GU5 in mine so will check on my next drive this weekend. If you are at about 2400 rpm the prev owner might have installed an even higher gear ratio, so accel is better but revs more in OD. If indeed you have a GU2 or even a GU5 then 2400-2500 at 70 mph does seem a little high to me. It would seem like the Torque convertor might not be locking up. I dont meean to scare you by the way, its just a suggestion. When you drive the car you should have the 3 gear changes, 1-2 then 2-3 and then 3-4. But when in 4th at about 40-45 mph the revs should drop further, like another small gear change, as the torque convertor clutch locks up for better economy. second answer, re service of auto box, it's recommended that it is done maybe about every 70K miles. However some dont do it at all and some say everything is long life. You have to drop the pan (and get covered in ATF) then pull the filter and renew it. You must carefully remove the metal/plasic filter seal and put in a new one without scratching the bore the seeal sits into. Then refil with ATF. I used some triple QX recently from euro car parts as long as it meets the dexron 3 requirements it should be fine. Mine has been fine and it gets a LOT of abuse sometimes (at strip etc). Some people have reported that servicing a 100K + gearbox if its not being done before is BAD. They say as the deposits are washed out that were previously stuck to the clutch plates in the box that it will start to slip. Some people have said they have had no problems? Just the way it goes. let me know if you need anymore help, or send me a PM 
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| Author: | SR-71 Blackbird [Fri Nov 30, 2012 6:24 pm ] |
| Post subject: | Re: General servicing re the auto gearbox in a Z28 |
Hiya, Thanks for the comments. I really appreciate them. Just to check I'm not doing anything stupid re the overdrive. I simply start her up, move into D with the box around it, then drive to motorway (10 mins) then blast up the hill onto the flat and cruise at 70mph. There isn't a special button or anything to engage overdrive is there? I assume it does it automatically based on speed and throttle position? More accurate data, at 70mph on the flat 2300rpm, 80mph 2600rpm I will try to see if the paperwork says anywhere about the gearing and the maintenance about the diff and oil changes etc. If I can't find anything is there any other way I can check? maudyZ28 I will send you a private message too  Thanks guys Thanks guy |
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| Author: | SR-71 Blackbird [Fri Nov 30, 2012 6:27 pm ] |
| Post subject: | Re: General servicing re the auto gearbox in a Z28 |
Just had a thought, my gearbox has 1, 2, D and D with a box around it. Is that what the other 1998 autos have? |
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| Author: | z28stu [Fri Nov 30, 2012 10:39 pm ] |
| Post subject: | Re: General servicing re the auto gearbox in a Z28 |
Yep sure is will take pic tomorra for peace of mind K I cant upload it SR71 as the files too big by 0.16mb an dont know apart from signing up to another online photo sharing website how else to post it  
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