Has anyone had a problem of 400's with brakes slipping 6 or 8 hundred rpm when they shift?? One guy had a readout from his tach,to prove it.
I know of three!! Two that I built and one COAN . All of the tranny's have different clutches and different brakes, yet are doing the same thing.
I was able to check the pressure on one of mine and it was 225 lbs.[which should be good]
The guy with the COAN trans said he called COAN about his and was told that this is a common thing with 400's and he should just shift earlier??
Anyone with any experience with this problem or any answers to this problem??

never seen 600 to 800 rpm slippage unless the engine is over powering the clutch packs of the tranny.

which gear shift are we talking about? 2nd or 3rd or both?

How many frictions in the clutch packs? 6, 7 or 8 in the direct? 3 or 4 in the intermediate ?

Kolene steels or regular steel plates

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At the Bonneville Salt Flats... 130mph is known as First gear ...............

2nd is worse - 6 or 8 hundred rpm.
3rd is - 3 or 4 hundred rpm.
I beleive all the clutch packs are different.
The first one I built had red and kolenes. 3 in second and 7 in 3rd. I built the guy a new one using blues and regular steels,3 in second and 5 in 3rd, and it does the same thing?[mayby worse,800 to 1000 rpm?] They both had new pro-tree TCI trans brakes. In the last one I changed the valve body to a TSI regular brake, but no difference. I ended up giving the guy his money back and installing his PG [ which I freshend up for him]
The 3rd trans is a COAN. All the ones I've seen he uses B/W clutches [ nothing trick, but they WORK]
F.Y.I.- The [2] I built were in a 3000 lb. car with a 555 ci. engine running low 9's. The COAN is in a 3400 lb. car with a "street" 540 ci. running low 10's.
I have built and freshed many 400's with brakes , but they were in slower cars, and never had a problem with them.

When all is working correctly , the only time I have seen any slippage in operation is when the t-400 was behind a blown alky motors in funny car or monster trucks when the GM based trucks used the t-400. Freshening the tranny was a regular maintenance item. Many of the GM based trucks now use power glides

Did you drill any relief hole in the direct drum for faster release of the clutch during trans brake operation? what size if you did?

I have installed 4 frictions in 2nd gear for a large HP application.

I am not a fan of kolene steels. I use regular when possible.

225 psi is good to get the job done. If you get much higher ..... the 2nd gear case lugs like to break out

I am not familiar with the design and fluid operation of the TCI t-400 trans brake products. I use our own manufactured v-bodys. I seem to remember a check ball or two in the trans brake units?

Do you use teflon sealing rings? I like them

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At the Bonneville Salt Flats... 130mph is known as First gear ...............

The car does not seem to be OVERPOWERING the clutch packs. The trans seems to shift SLOW, even in the water box, warming the tires.
All the other 400's I've built seem to shift as soon as you move the shifter. This one seems DELAYED??
I have checked the shifter in everyway - It's perfect in every gear.
Yes I drilled the relief hole = .062
This trans has BLUE clutches + STANDARD STEELS
I have the t/f .106 snap ring to help the case lugs.
The only check ball is used to plug the accumilater drain.
Yes I use telon sealing rings, also.
I leave the second sealing back on the center support, off.
Would a HUGHES v/body give me a POSITIVE shift?