Problem with 5-6 gearchange in a Cadillac CTS-V
04-18-2007, 07:22 PM
#1
Staging Lane
Thread Starter
Join Date: Oct 2004
Location: Salem, OR
Posts: 58
Likes: 0
Received 0 Likes
on
0 Posts
Problem with 5-6 gearchange in a Cadillac CTS-V 2005 Cadillac CTS-V with Tremec T56 Transmission (M12). 49,200 miles
Symptom: Pops out of and/or difficult/impossible (grinding) to engage 6th gear from 5th. This condition occurs intermittently, but almost always occurs with very light throttle upshifts from 5th to 6th at slow speeds, 35 mph or less. Shifts from 5th to 6th in these conditions are typically made in city boulevard driving where traffic is light and on downgrades. The transmission/motor are very lightly loaded and no lugging occurs. This condition first appeared maybe 5,000 miles ago, and at first I thought it was a human shifting error. Lately, it is occurring more frequently; and I have now confirmed that it is not a shifting error when I can replicate the condition back-to-back with lots of care taken in shifting. However, sometimes it just shifts normally.
I have seen worn sycros in other cars, but it usually occurs in the 1-2 shift from repeatedly “beating the syncros”. It doesn’t feel like the syncro is being “beaten”. It feels like it is refusing to go into 6th – period.
I had a UUC shifter installed at 13,383 miles. UUC advertises this shifter as being the same interior height as OEM, but with 30% shorter shifts. The shifter is a rod with a round fulcrum. My sense is that UUC lengthened the shifter below the fulcrum; and that this should have no effect on shift lever placement. If anything the longer extension should place the shift levers more firmly at their “stops”. Also, if it was the shifter I think it might also show problems in other gear changes.
Local Cadillac dealer has done a driving test and wonders (naturally) if it the problem is caused by the shifter. Nevertheless, the Cadillac dealer took a bone stock CTS-V from their lot and replicated the condition.
I tried another experiment today – shifting without the clutch. My experience on other cars has been that one can clutchless shift more easily in higher gears. I found it impossible to clutchless shift from 5th to 6th at highway speed.
Note, the car is not driven hard. It is never “launched”. I always have gotten at least 100,000 miles from OEM clutch discs. This car is used mostly for travel with the vast majority of its mileage (well over 95%) in 6th gear.
Transmission History
• 4830 miles – transmission fluid changed. Mobil 1 Dex III added.
• 13,383 miles - UUC shifter added. I don’t believe the shifter is a cause of the problem. The big change in the shifter design, which shortens travel, is to lengthen the section below “ball”, which should, if anything, cause the shifter to better “seat” each shift. There are over 800 messages respecting the UUC shifter in www.cadillacforums.com, and none speak of the shifter causing any shifting problems.
Symptom: Pops out of and/or difficult/impossible (grinding) to engage 6th gear from 5th. This condition occurs intermittently, but almost always occurs with very light throttle upshifts from 5th to 6th at slow speeds, 35 mph or less. Shifts from 5th to 6th in these conditions are typically made in city boulevard driving where traffic is light and on downgrades. The transmission/motor are very lightly loaded and no lugging occurs. This condition first appeared maybe 5,000 miles ago, and at first I thought it was a human shifting error. Lately, it is occurring more frequently; and I have now confirmed that it is not a shifting error when I can replicate the condition back-to-back with lots of care taken in shifting. However, sometimes it just shifts normally.
I have seen worn sycros in other cars, but it usually occurs in the 1-2 shift from repeatedly “beating the syncros”. It doesn’t feel like the syncro is being “beaten”. It feels like it is refusing to go into 6th – period.
I had a UUC shifter installed at 13,383 miles. UUC advertises this shifter as being the same interior height as OEM, but with 30% shorter shifts. The shifter is a rod with a round fulcrum. My sense is that UUC lengthened the shifter below the fulcrum; and that this should have no effect on shift lever placement. If anything the longer extension should place the shift levers more firmly at their “stops”. Also, if it was the shifter I think it might also show problems in other gear changes.
Local Cadillac dealer has done a driving test and wonders (naturally) if it the problem is caused by the shifter. Nevertheless, the Cadillac dealer took a bone stock CTS-V from their lot and replicated the condition.
I tried another experiment today – shifting without the clutch. My experience on other cars has been that one can clutchless shift more easily in higher gears. I found it impossible to clutchless shift from 5th to 6th at highway speed.
Note, the car is not driven hard. It is never “launched”. I always have gotten at least 100,000 miles from OEM clutch discs. This car is used mostly for travel with the vast majority of its mileage (well over 95%) in 6th gear.
Transmission History
• 4830 miles – transmission fluid changed. Mobil 1 Dex III added.
• 13,383 miles - UUC shifter added. I don’t believe the shifter is a cause of the problem. The big change in the shifter design, which shortens travel, is to lengthen the section below “ball”, which should, if anything, cause the shifter to better “seat” each shift. There are over 800 messages respecting the UUC shifter in www.cadillacforums.com, and none speak of the shifter causing any shifting problems.
