Changing Shift pattern... HELP! (please...)
02-16-2009, 08:12 AM
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Changing Shift pattern... HELP! (please...) Fella's I recently installed a new set of 4.10s and whether or not it is coincidental is unknown, but the first night at the track with the 4.10s she seemed to bump off the rev limiter at the top of 1-2 shift, missing slightly.. and hesitating on the shift.
2-3 however was completely different. She would hang so long that she would literally nose over and buck miss just like she was tapping the limiter... I just assumed that it was the new set up screwing with the tune, so I sent the PCM to Bryan at PCM for less, cause the last time he nailed the tune... the car ran beautifully after the rebuild knocking a full second off the 1/8th mile ETs on the first run.
How on this trip, it mildy improved the delay, it still bucks, just not as badly...
This last Friday night, she would roll to the top of 1st, hitting around >6500rpm (indicated), hang, cut off, then shift to 2nd... a regular at the track actually came over and asked me if I'd converted to a stick... 2-3 seemed the same, only not as bad as the previous outting; better but still hanging.
Someone said the 12" re-man'd 2500 stall may be on it's way out... someone else said the 2-3 shift packs may be wearing... another said servos. She's heading to the tranny shop next week... I had the tranny built for racing when I had it rebuilt... I paid $2700 for the work... the guy came highly recommended... and said he used 'corvette servo's and clutches... but hell, who knows? It's got maybe 5000 miles on it since then.
Now the only other thing I've done, which could possibly be connected, is the EWP install where I failed to rag the top of the Opti and we spilled a fair bit of coolant...
I'm sure that this issue is robbing us of at LEAST a tenth and possibly 2...
Any thoughts?
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2-3 however was completely different. She would hang so long that she would literally nose over and buck miss just like she was tapping the limiter... I just assumed that it was the new set up screwing with the tune, so I sent the PCM to Bryan at PCM for less, cause the last time he nailed the tune... the car ran beautifully after the rebuild knocking a full second off the 1/8th mile ETs on the first run.
How on this trip, it mildy improved the delay, it still bucks, just not as badly...
This last Friday night, she would roll to the top of 1st, hitting around >6500rpm (indicated), hang, cut off, then shift to 2nd... a regular at the track actually came over and asked me if I'd converted to a stick... 2-3 seemed the same, only not as bad as the previous outting; better but still hanging.
Someone said the 12" re-man'd 2500 stall may be on it's way out... someone else said the 2-3 shift packs may be wearing... another said servos. She's heading to the tranny shop next week... I had the tranny built for racing when I had it rebuilt... I paid $2700 for the work... the guy came highly recommended... and said he used 'corvette servo's and clutches... but hell, who knows? It's got maybe 5000 miles on it since then.
Now the only other thing I've done, which could possibly be connected, is the EWP install where I failed to rag the top of the Opti and we spilled a fair bit of coolant...
I'm sure that this issue is robbing us of at LEAST a tenth and possibly 2...
Any thoughts?
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Last edited by OVA1; 02-16-2009 at 08:56 AM.
02-16-2009, 09:08 AM
#2
You may just need to allow more room from command to shift, The 410 gears cause the RPM to increase at a more rapid rate than before. The time to complete the shift from command to actual is unchanged, So more rpm pass in this time, I see this alot after a gear change people ask about it and that ussually solves the issue. Where before it may have only taken 200 rpm to complete it may take 300-500 or more to complete with the new setup depending on the trans.
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02-16-2009, 09:39 AM
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You may just need to allow more room from command to shift, The 410 gears cause the RPM to increase at a more rapid rate than before. The time to complete the shift from command to actual is unchanged, So more rpm pass in this time, I see this alot after a gear change people ask about it and that ussually solves the issue. Where before it may have only taken 200 rpm to complete it may take 300-500 or more to complete with the new setup depending on the trans.
Thank you very much!
Now (and I know this is a stupid question) but that is a PCM issue, right? Not something my tranny guy would do? My car doesn't really have a "tuner" available for it; apparently requiring some expensive program... which I definitely do not have; so I have to send the PCM in for changes.
My tranny guy has an honest old guy that's been rebuilding tranny's for 40 years... but he's defninitely NOT a speed shop... very old school. So while I don't know for sure, it's fairly unlikely that he's going to program my tranny.
Again, thank you VERY MUCH for taking the time to offer your input.