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Naturally the synchos are meant to take the brunt of the abuse, but you may want to look at the gear itself and the engagement teeth and the sliders! They don't last forever! You didn't indicate any jumping back to neutral which is good! On power shifts to other gears, do you have problems in just the fore to aft direction of shift or also the side to side?
I still will call any stab of the clutch, with a lift of throttle as a speed shift!
A clutch less shift, no lift a power shift!
A clutch less shift, with a lift of the gas pedal a board shift (or I call that a bored shift!)
Last edited by TCracingCA; Oct 18, 2016 at 03:17 PM.
Triple Black runs the Keisler SS600 or 700 Tranny and it has already been apart for other issues. Not good in a new tranny.
The 327 he runs is highly modified and I think he runs it to 7,500 when racing.
The Keisler tranny was advertised to shift like butter above 6,000 RPM. I have no idea why this car is reluctant to power shift.
Any chance the engine is twisting in the frame enough to change your shift linkage and mess up the clutch?
Don't have an answer as to why Joe can't power shift above 6,500. Perhaps there is some misalignment going on per Westlotorn's post.
Do have to share my 1 time result of power shifting with a street clutch with my wide ratio Muncie (M20). The leap from 1st to 2nd was unbelievable, 2nd to 3rd...not so much. I went home early.
Here's a few pics as a result of this. Literally wiped off all clutch material. All that was left was the metal backing When I pulled the bell housing away, I looked like a chimney sweeper after all the burned clutch material dumped on me. Shifting was at 6,500 rs'.
Ready to race at Milan
Sitting dead on the return run waiting for a tow back to the pits.
Has the OP drained and examined the trans fluid? A visual check for brass/bronze filings ought to be a reality check on the synchros; a magnet check ought to show any pieces of the gear teeth.
BTW even the Urban Dictionary (don't go there) knows you use the clutch on a powershift
If you watch the Grump shift, he is using the clutch.
I agree a slipping clutch should not cause the issue of not being able to shift, unless the pressure plate is locking at high rpms... and I have seen/heard of that happening.
The secret to avoiding that was the clutch had to be put in, the shift lever moved, and the clutch released in a split second. With practice and good coordination, it sounded almost like an automatic. But yes, as you say if you did NOT get it into gear, it was not good. Going 1 to 2 was not bad because it was a straight pull back. You were more likely to get into trouble on the 2-3, where you had to push forward, right and forward again. You could get hung up in the gate going to the right and wind up in neutral, or worse yet accidentally shove it back into first instead of third.
Oh, the good old days, when I was bulletproof (and stupid!)
^^Good description of how it should be done.
The shift lever is in motion a split second before the clutch disengages and when the timing is right it sounds and feels like an automatic. The key, however, is in breathing the throttle just for an instant to synchronize engine and gearbox revs. A blip is used on the downshift for the same reason. Non-synchro boxes require doubleclutching (clutch out and back in while passing through neutral) to avoid the grind.
Of course dragracers aren't concerned with sissy stuff like synchros, downshifts, braking, and turning
Sorry for the late reply. Been away for a couple days.
First, the trans is a low mileage RS600 from Kiesler. Was torn down last year and examined. Everything is in excellent condition.
No I don't normally powershift. But I'd like to be able to get this trans to do it, occasionally, for fun. I can't powershift 1-2 because the car goes sideways and not confident enough to go 2-3 but 3-4 would be fun on rare occasion. Main reason is simply to see if it is capable.
Powershift at 7250 won't happen. The shifter just won't "go" as hard as I can manage to pull or push into next gear. Again..................I won't try 2-3. I'll leave that for Donny Brass.
The clutch is a RAM HDX rated to 450 HP. Maybe it's not up to par since I'm about 30 HP above that. Clutch is AOK, and works normally during normal driving.
What happens is, during a powershift at 6500 ,which is the highest limit that the drivetrain (and I, according to Donny) will accomplish, it SOUNDS like the clutch takes about 1/2 second to fully hook up. In other words, the revs don't drop quickly, like an automatic, but take about1/2 second to fully slow down. Maybe I'm expecting too much.
Last edited by 65tripleblack; Oct 19, 2016 at 11:34 AM.
BTW even the Urban Dictionary (don't go there) knows you use the clutch on a powershift
If you watch the Grump shift, he is using the clutch.
I agree a slipping clutch should not cause the issue of not being able to shift, unless the pressure plate is locking at high rpms... and I have seen/heard of that happening.
Hey Donny. Hopefully next year we'll meet and I'll give you the helm. Couldn't make it this year. When I watch your race videos, it sounds like you're powershifting all three changes, and I assume you're at around 6000 with your hydraulic cam and lifters. As you already know, I don't trust myself 2-3; 1-2 the car goes sideways badly and I have to lift otherwise it'll just keep spinning tires.
I had "overcentering" problems with Borg Warner heavy duty clutches. No such problem with this RAM. It just seems to slip a bit. I'd like it to grab and hold FULLY immediately. In other words, I don't get thrown back in the seat because the shift is a bit "gentle" due to "slight" maybe 1/2 second period while the clutch is trying to equalize input shaft speed to engine speed. I'm using a 15 pound steel flywheel and maybe that has something to do with it.
Over this winter I will install my Quick Time steel bellhousing to replace the present cracked aluminum stock bell.
Last edited by 65tripleblack; Oct 19, 2016 at 11:37 AM.
I shift around 6400, better to make a little noise then let the rpm drop too far.
with the new description, I am thinking the clutch is not releasing fully, keeping you from pulling the lever. now it is glazed, hazed, and not releasing or grabbing fully.
Last edited by Donny Brass; Oct 19, 2016 at 12:10 PM.
Sorry for the late reply. Been away for a couple days.
First, the trans is a low mileage RS600 from Kiesler. Was torn down last year and examined. Everything is in excellent condition.
No I don't normally powershift. But I'd like to be able to get this trans to do it, occasionally, for fun. I can't powershift 1-2 because the car goes sideways and not confident enough to go 2-3 but 3-4 would be fun on rare occasion. Main reason is simply to see if it is capable.
Powershift at 7250 won't happen. The shifter just won't "go" as hard as I can manage to pull or push into next gear. Again..................I won't try 2-3. I'll leave that for Donny Brass.
The clutch is a RAM HDX rated to 450 HP. Maybe it's not up to par since I'm about 30 HP above that. Clutch is AOK, and works normally during normal driving.
What happens is, during a powershift at 6500 ,which is the highest limit that the drivetrain (and I, according to Donny) will accomplish, it SOUNDS like the clutch takes about 1/2 second to fully hook up. In other words, the revs don't drop quickly, like an automatic, but take about1/2 second to fully slow down. Maybe I'm expecting too much.
Well............Donny says that he has several documented 10,000 rpm "non-shifts", so........how much can you afford?
I shift around 6400, better to make a little noise then let the rpm drop too far.
with the new description, I am thinking the clutch is not releasing fully, keeping you from pulling the lever. now it is glazed, hazed, and not releasing or grabbing fully.
I know you don't want to discuss your camshaft, but I'm assuming that your hydraulics are zero lashed with shifts that high.
Could be..........maybe my timing is a few milliseconds "off". As I said, 3-4 PS is fine at 6500 R max.
As far as being glazed, I don't think so. But I'll examine it carefully over this winter when I install the new bell.
I hope you use a steel bell as well. Hate to lose a good guy like you.
TO ALL:
I think I pushed my luck far enough, so the crack in the 403 bell urges me to upgrade. The crack goes from the engine mount flange across to the fork opening. Maybe that crack opens up under load and momentarily misaligns the trans pilot in the needle bearing in the crank.
Last edited by 65tripleblack; Oct 19, 2016 at 07:39 PM.
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I'm just hoping that you're using a steel scatter-shield when you're shifting like that. There's only a fiberglass floor between your feet and the exploding disc/flywheel if it comes apart.
My brother's 60 had major floor work done on it after an exploding clutch took 2 toes off the previous owner at the strip in the old days.
Triple Black you have described two issues. One, the slipping clutch. Either your pressure plate is not up to the HP task or the linkage is not allowing it to release fully.
My buddy built a 72 340 4 speed Challenger, beautiful car. His rear tires were 11 inches wide each with posi and a 3.23 rear gear. Brand new clutch. His 340 is massaged probably making 400-425 HP. The factory style clutch would not grab under full throttle he had to upgrade. He was not aware of this until he went to the drag strip. He thought he was having traction problems until he smelled his clutch burning up.
As far as not being able to shift it, could still be the clutch. If it is slipping under full throttle they get really hot really fast and lose tension on the disc.
I had a 72 Blazer back in the day with oversize tires. Worked great all the time until I went in Sand. The sand was so much load on the drive train that the clutch would start to slip and overheat. The first sign this was happening was me not being able to shift the tranny. With all the noise I never really knew when I was spinning tires in the sand and when the clutch was slipping, maybe both at the same time but the clutch would stop working and the tranny felt locked.
Sounds like you need a new clutch if you rule out a linkage issue.
6500 rpm isn't that high. I'll show you some of my dyno sheets to 8500.
Joe you are fighting a battle I don't think you can win with the transmission you have.
Originally Posted by Westlotorn
Triple Black you have described two issues. One, the slipping clutch. Either your pressure plate is not up to the HP task or the linkage is not allowing it to release fully.
My buddy built a 72 340 4 speed Challenger, beautiful car. His rear tires were 11 inches wide each with posi and a 3.23 rear gear. Brand new clutch. His 340 is massaged probably making 400-425 HP. The factory style clutch would not grab under full throttle he had to upgrade. He was not aware of this until he went to the drag strip. He thought he was having traction problems until he smelled his clutch burning up.
As far as not being able to shift it, could still be the clutch. If it is slipping under full throttle they get really hot really fast and lose tension on the disc.
I had a 72 Blazer back in the day with oversize tires. Worked great all the time until I went in Sand. The sand was so much load on the drive train that the clutch would start to slip and overheat. The first sign this was happening was me not being able to shift the tranny. With all the noise I never really knew when I was spinning tires in the sand and when the clutch was slipping, maybe both at the same time but the clutch would stop working and the tranny felt locked.
Sounds like you need a new clutch if you rule out a linkage issue.
Dave and Mark,
Dave. First of all, the posi works perfectly and is quiet with no clutch bang. My biceps grew 3" with all that pulling and pushing on the breaker bar to wear in the clutches. Kudos to you and "happiness is a tight posi" Tom.
Maybe it's wheelspin that I'm feeling/hearing....................as I said before, I'll only powershift 1-2 (2-3 I won't gamble on......yet) and that produces a lot of wheelspin. Come to think of it, I'll bet that's what it is.
I'll find some open road and give 3-4 a try. This puts me at about 90 plus MPH @ 6500 RPM. I have a strong feeling that this will be instantaneous and positive (unless the wheels spin badly during the 3-4 shift, which is unlikely).
The matter of not being able to yank the shifter into the next gear @ 7300 RPM might be a function of my trans, so you might be right. Although, FWIW, Shafi K told me that it would be good for 7500.
As I said earlier...the pressure plate is rated for 450 HP. I'm 35 over that, but I doubt that the 35 extra horses would make that much difference.
It's also possible, I think, that the crack in the bell is causing alignment issues under more extreme loading. The only way i'll know, for sure, is after I replace the bellhousing and either borrow or buy a set of slicks.
Last edited by 65tripleblack; Oct 20, 2016 at 10:37 AM.
Dave. First of all, the posi works perfectly and is quiet with no clutch bang. My biceps grew 3" with all that pulling and pushing on the breaker bar to wear in the clutches. Kudos to you and "happiness is a tight posi" Tom.
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When I pulled the bell housing away, I looked like a chimney sweeper after all the burned clutch material dumped on me. Shifting was at 6,500 rs'.
