[Bob with the 66]

Ok, I have finally been able to drive my build around the block for a test drive. (865hp, T400 manual valve body, Dana 60, 4.11 on a spool, 33" dia. rear tires)

So can someone tell me the correct do's and don'ts in driving a manual valve body T400 transmission?

When driving the car on the street, do I shift from 1st to 2nd to 3rd from every stop or is it safe just to leave from 3rd every time?

If I want to do a burnout, is it safe to do in 1st gear or should it be done only in 3rd gear?

I know these are some simple questions but to a guy that has always driven a manual trans GTO and never driven a car at this level I do not want to do anything wrong.

Thanks, Bob

[Mr Anonymous]

> If I want to do a burnout, is it safe to do in 1st gear or should it be done only in 3rd gear?

3rd gear only, if you engine will do it (yours probably will), or start it in 2nd and go to 3rd. No 1st.

[68blackbird]

Start only in 2nd?

1st gear is really a no no?

Rich

[Bob with the 66]

Originally Posted by Mr Anonymous

> If I want to do a burnout, is it safe to do in 1st gear or should it be done only in 3rd gear?

3rd gear only, if you engine will do it (yours probably will), or start it in 2nd and go to 3rd. No 1st.

Thank you for the burnout direction for the drag strip.

What if I want to chirp the tires on the street, is it safe to start in 1st gear or keep it in 3rd gear?

[Bob with the 66]

Originally Posted by 68blackbird

Start only in 2nd?

1st gear is really a no no?

Rich

So is 1st gear just for drag racing and not to be used on the street?

Can you provide some detail on the no - no statement for a newbie?

Thanks Bob

[Mr Anonymous]

My information was for burnouts only. Do burnout in 3rd only, or start in 2nd and go to 3rd.

On the street, use all the gears, and wear it out. that's what its for!

[78w72]

Originally Posted by Mr Anonymous

My information was for burnouts only. Do burnout in 3rd only, or start in 2nd and go to 3rd.

On the street, use all the gears, and wear it out. that's what its for!

curious why no 1st for burnouts? can you explain the reasoning for this?

i use 1st gear for burnouts on the street & at the track with no issues or problems at all. i run drag radials & they dont require big long burnouts, just enough to start smoking then roll out, no need for high tire speed 3rd gear john force type burnouts. i see other more serious racers use 1st for burnouts as well.

[Mr Anonymous]

Best explanation I've found (from Yellowbullet):

Originally Posted by F.Rizzo

THM 400 rev. manual w/t-brake clutch & band application

Reverse - Direct clutch & Rear band

1st gear - Forward clutch is applied & the Low roller clutch is holding (needs to see load)

1st gear w/brake on - Forward clutch, Direct clutch, Low roller clutch holding & Rear band applied.

2nd gear - Forward clutch is applied, Intermediate clutch is applied & Intermediate sprag is holding

3rd gear - Forward clutch is applied, Intermediate clutch is applied, Direct clutch is applied & Intermediate sprag is overrunning.

THM 400 Gear-train

1st gear under acceleration - Front planetary/reaction carrier is being held stationary from the low roller clutch locking against the center support, the rear planetary/carrier is rotating with the driveshaft, the direct drum is being ant-irotating via the sun tube @ a speed determined by which gear set is in the trans (2.48/1st is 84% of input shaft speed). The combination of both the front & rear planetaries gives you first gear.

2nd gear under acceleration - The intermediate clutch is applied & along with the Intermediate sprag holding this stops the dirct drum from antirotating & also releases the low roller clutch which intern eliminates the front planetary/reaction carrier. Now the only active planetary is the rear one thus giving you second gear.

3rd gear under acceleration - The Intermediate clutch stays applied & the direct clutch is also applied which allows the Intermediate sprag to freewheel thus eliminating the rear planetary & giving you 3rd gear.


The low roller clutch is designed to work under load & for this reason it is highly recommended that you do not do burn outs or hard peddle the car while in first gear. The loading & unloading of the low roller clutch causes the rollers to slam against the springs & flatten them. If the low roller fails under load it will send the direct drum to 3.25 + times engine speed, usually very bad when there is a cast drum involved. Another big issue is the Intermediate sprag also works under load, it needs moments of time to load the sprag elements properly & also the sprag race dimensions come into play. Now we are only talking about millisecond, but this is accomplished by bringing the motor down to driveshaft speed during the gear change, where as in the burrn-out you are bringing the driveshaft up to engine speed during the gear change which can & will "shock load" the Intermediate sprag.

Remember when in 1st gear you are anti-rotating the direct drum then stopping it to get second which in a burnout situation this unloads the low roller rapidly & has to lock the intermediate sprag with out the proper "time" to load. This will cause unnecessary wear & abuse to the sprag, then resulting in premature sprag failure

[Keith Seymore]

I do the burnout in second gear (no shifting).

On the street you will need to cycle through the gears (start in first, shift to second, shift to third). You will be very disappointed if you try to start out in third gear all the time, as it will be quite doggy.

So it's kind of like driving a manual trans, but with no clutch.

K

[Bob with the 66]

Originally Posted by Keith Seymore

I do the burnout in second gear (no shifting).

On the street you will need to cycle through the gears (start in first, shift to second, shift to third). You will be very disappointed if you try to start out in third gear all the time, as it will be quite doggy.

So it's kind of like driving a manual trans, but with no clutch.

K

Keith, is it true I should not down shift when slowing down unless I'm under "say" 20mph on the street?
And NEVER down shift on the drag strip?

[Keith Seymore]

Originally Posted by Bob with the 66

Keith, is it true I should not down shift when slowing down unless I'm under "say" 20mph on the street?

I would say yes. You will probably want to come nearly to a stop before pulling down into first.

Originally Posted by Bob with the 66

And NEVER down shift on the drag strip?

ABSOLUTELY YES! That could cause some excitement.

K

[Bob with the 66]

Thank you all for your input, and it might sound like silly questions but I have never had the opportunity to use or drive a RMVB transmission so your help is greatly appreciated.

Bob,

[Mr Anonymous]

having a transbrake / manual VB trans is like the mechanical version of crack. Always wanna use it!

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