Is this the correct passage in the case to block the 3-4 accumulator feed, so that all the oil will go to the clutches (bypassing the 3-4 accumulator)? I know most shift kits use a stiffer spring or shims to limit spring travel in the 3-4 accumulator, but to totally bypass the 3-4 accumulator entirely, is this the passage to block to achieve this? Picture attached with pencil inserted into passage in question. Thanks.
Blocking 3-4 Accumulator
- Thread starter KEhrhardt
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Well, I was hoping for atleast one 'been there did that' reply. OK, I think I answered my own question here. I think that this is the correct place to block off the 3-4 accumulator to take it out of the 3-4 circuit. In the theory of operations manual it shows 4th gear oil going to the 4th clutch pack and also through a pressure switch to the 3-4 accumulator. This passage is now blocked with a plug on 3-4 accumulator end (where the pencil is) and by tracing this passage out it appears to feed the pressure switch in the VB, (it's a little tricky to line up the VB and follow the passages) on its way to the 4th gear clutches. So on the 3-4 shift, governor oil pressure overcomes the 3-4 shift valve spring and allows mainline pressure to enter the 4th gear oil circuit. Since the accumulator is blocked on one end of the circuit, (note 4th oil still passes by the pressure switch), all the 4th gear oil goes to the clutches. :smile:
Your correct but its not a wise move to delete that particular accumulator if you use anymore than the stock clutch configuration. If your using reds or more than 2 clutches for OD the risk of breaking the planet where the input splines into is greatly increased. The input itself will be more prone to breakage also. Contact Chris at CK for a spring that will accomodate your needs.KEhrhardt said:
77 cruiser
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With an extra friction in OD it shifts plenty firm. I'd like to even tame mine a bit. I've tried the acc. piston both ways & no diff. but it would be way too hard with the acc. blocked I think.
You also have to watch out with the blocked off 4th accumulator that if you are in lockup and go to 4th, you could knock the back window loose or out. Been there/done that with my 84 T. Now I have a 727 accumulator spring in place so there is "some" accumulation and 4th still shifts firm under more than 1/4 throttle. 
Hrrrmmm.... Well perhaps I went too far this time. I have the 3 clutch Alto pack from TCI in this rebuild. Looks like I need to remove the plug then. Easier said then done since it has some loctite on it. Maybe a little acetone or nail polish remover will loosen up the loctite. We'll see.
77 cruiser
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A little heat will loosen the Locktite.
77 cruiser
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I wouldn't block the 1-2 either. Once mine got a few miles on it , it shifts plenty firm 1-2. Alto wide band with 200c servo, plate hole is .110.
But that's me.
But that's me.
Firechicken
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I blocked the 1-2 in mine and with a stock MCSS D5 converter, the shift is hard and chirps the tires. When I had the old POS converter with the high stall, the shift was only slightly firm.
With my new PTC (Alabama) converter, since the stall is higher, the shift likely won't be as hard as the D5, but hopefully should still be firm.
In my opinion, if you have a stock converter and don't want super hard shifts, don't block the 1-2. If however, you have a higher stall, the higher stall will 'cusion' the shift, so blocking the 1-2 can be a good thing. In my case, I like hard shifts, so I enjoyed the hard shifts even with the stock converter.
With my new PTC (Alabama) converter, since the stall is higher, the shift likely won't be as hard as the D5, but hopefully should still be firm.
In my opinion, if you have a stock converter and don't want super hard shifts, don't block the 1-2. If however, you have a higher stall, the higher stall will 'cusion' the shift, so blocking the 1-2 can be a good thing. In my case, I like hard shifts, so I enjoyed the hard shifts even with the stock converter.
I have the 1-2 accumulator blocked as well. I have a SnapOn heat gun and a propane torch so I guess I can heat up that loctite. :smile: Cam wakes up at 3000-6000 rpm, but it is a SBC 383 stroker ~450HP so there is a ton of torque in the lower RPM range. A restalled D5 might be ok, but I was going to go with a 2800 rpm 9/11. The car is a 66 Chevelle with a 12 bolt 3.73 posi and 255/60R15 (27" tall tire). It will be relatively heavy, probably ~3900lbs with me in it.
HellOnWheels
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jakeshoe said:
What's so special about the 727 spring? I have the 3 clutch OD setup also, and anything I can do to help the shift but more important to me is longevity I would like to do while my trans is out of the car.
TIA
HOW
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jakeshoe said:
Jake, restalled D5 stalls 28-2900 with the foot brake.
Firechicken said:
I like a hard shift as well, but I don't want the car going sideways on the 3-4 shift at 60mph nor blowing out the back window either. However, I think with the 2800 9/11 converter, or a CK 10/12 converter, blocking both the 1-2 and 3-4 accumulators will work and not be too violent. IIRC remember a post a while back from CK saying that he blocks the 1-2 and 3-4 when using a 9/11. Things do change, so Chris what is the current thinking on this?
blocking the 4th acc is a bad idea.the 1/2 can be blocked if you have a super loose converter such as some of the poorly designed tcs 9/11 pieces that caused my customers alot of problems awhile back.not all were "freak experiments "performed by tcs however.most of the stalls over 3200 produced such a poor coupling that this was the only way to be sure you had a good shift :biggrin: .ask norbs,j crawford,and bob from montreal.however as far as the accumulator goes the 3/4 with a new piston and new hduty spring as well as a slightly larger hole in the seperator plate will yield great results in most applications.as many of you know we like to accomplish this with extra frictions that is why we offer the 3 pack and better yet the 4 pack for overdrive.the hole in the plate is actually for what exits the shift valve not what feeds it like most other set ups.
HellOnWheels said:
The 727 spring is tall like the original 3-4 spring but there are more coils and are thicker and closer together. The stock spring will allow a lot accumulation compared to the 727 spring which will barely compress and the shift will happen quicker compared to the stock spring.
HellOnWheels
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GNeric said:
Eric,
Is the "727" a part number or ?
Thanks
