Are all TH400 dipsticks the same?
 

The top on my old dipstick broke off. I got a spare from a friend a while back and he said it was off an old, long tail TH400. I didn't think anything about it but when I run this in the "full" range of fluid it doesn't shift properly, almost like it's low on fluid. If I run it with a high fluid level it seems to shift OK. Anyone know?

Yes tube lenth matters
 

If the dip stick tube was a different length, it's not going to read right.
If it from the same model car, or body and engine style it'll be fine.

Remember that Recreation Vehicles used th400's too and they would obviously have longer tubes.

I put in a Lokar (aftermarket) dipstik. It inserts into the pan and goes about an inch into the th400 pan.

Hopefully someone will have more accurate info.

Good luck,
Greg

Precisely my point. I put this one in after a fresh rebuild. I filled it to FSM specs and it was well above the "full" indicator on this dipstick. It shifted fine. I drained some fluid to get it in the "full" zone. Now it's not quite right. If this is a problem I want to correct it with the proper tube and diptstick.

I'm guessing that the old broken one was thrown out, otherwise it would be simple to compare the two dipsticks to see if there is any difference.

I would bet that there are many different TH400 dipstick lengths.

More information. This came off a Pontiac 400 attached to a long tail from an "old big car". Since all Pontiac blocks have the same dimensions, wouldn't this make it the same?

Get the tube that came with the stick
 

If the tube will fit your car, you should have it made.

Since I put a th400 into a 64 Gp, I couldnt get the tube to work. That's why I went with the Lokar unit. You could shell out the 60 bucks and get a LoKar, but it's not what I would have liked to use. I also heard that I could get a trans pan that would allow my Slim Jim tube to work, but i have not found one yet.

I also thought about cutting a couple of pans and welding my slim Jim tube onto a th400 pan.

Different cars have different floor patterns.

NO NO NO

there were probably a dozen variations in lenght
as the body styles changed over the years, the lenght and shape of the tube had to change to match the body
you must have a matching stick and tube or you are whisting in the wind

So, any one with a 74 TA, 455 and an auto tranny willing to measure the dip stick for me so I can verify this, please?

dipsticks
 

I had a Pontiac Oil dipstick that was broke. I had both pieces, so I went to the junkyard and pulled a long dipstick out of a van. I marked the van distick and I still have it. I cut off about 3 inches from the van stick.

AC option
 

In your quest for the right dipstick lenth, don't forget to mention the AC option, whether you have it or not.

On the big cars it's this option that changes the tube lenth, at least for oil dipsticks.

My book indicates two indicators are still available.
10017293 70-1 F-body (M-40) and 74-5 ALL (M-40)
1239014 70 T-8/GP (M-40) and 71-3 ALL (M-40)

Brother, I owe you a drink! That's what I needed to know. So what book? Is that a Hollanders?

If the trans is full and you loosen the pan, fluid should just drizzle out if the fluid is warm. If it doesn't, adduntil it does and then mark the stick.

GM parts manual. My '74 Formula 400/400 measures 27". Pictures to follow soon...

Greg, have you tried the 65-70 full size Olds dipstick tube?? I still don't know if it will work. The trans pan you need is off of a 64 Caddy,(with a 400 of course).

I went out and measured this one. Tip of the pull handle to the tip of the stick is 26 inches. Houston, we have a problem!

Thanks steve
 

I'll look for the Olds pan, and please let me know if you ever run across the caddy pan that would accomodate the slim jim tube. It sounds like a tough find.

Sincerely,
Gerg

Here are the pictures, maybe you can mark it up to see where it sits. Used a dial caliper and it was .4" from the inner edge to where the tape measure is setting.

Yep, this one is considerable different. Looks like I have some looking around to do. Gotta find a right dipstick. Crap! We have a club race this weekend. I hate to race it if I don't know where there fluid level is.

You can't use the posted reference points and mark new ones on your indicator?