T-4s & rpms at cruise speed

As I prepare to put my T-4 back in the D. I have concerns about gearing. Having one of the few Automatics.( now don't go yuck just yeat) its a must for me. I'm even converting my super beetle.I have 3 spare trannys and overhaul kits. So Im set

I need to get a target Rpm to shoot for at a cruise speed of 60 mph. Im hopeing KRM will make me a custom ring and pinon for a automatic. They do offer custom cut gears for the 4 and 5 speeds So theres a good chance.

So to all you T-4ers out there. Check your tacks at 60mph 'PLEASE" And if anyone has a formula to caluate tire size top gear and final drive ratios ? that would be Great!!!!

I got 2800 @ 60mph-- its a 2.0 L hydr. lifter with 3.88 type 1 trans running on 175/65-15 tire,
914 speedo...
clocked by my 'bro running longside in a boxter
regards DT

Only 2800?
My T-1 is around 4,000 at 60. I will definaly have to raise the gearing for the T-4,or second to third shifts will kill it in no time. I've seen 5,500 a few times with the T-1

It's a 2056 solid lifter. twin 44 webers I will be running the same tires 195/65/15s The tire size killed me, but that's the biggest thing that will work.

At what Rpm do you feel your engine is most happy purring along and not over worked, regardess of the speed? I may have to ask KRM if they can also remake the plantery sets in the second to third clutch pack. for little steeper shift.

A good average RPM vs MPH is to double the tach to get the miles per hour. 3000 RPM is usually right around 60 MPH in fourth. It varies just a little, but works for most all cars and is pretty much optimum.

Luck.

Barry,

I have a simple Excel spreadsheet that allows user input for all the various gear ratios, max RPM, the tire circumferance, and the differential ratio, and shows the speed at the designated rpm etc.

It is nothing complex, but I can send it to you if you like....just send me your email address jdubois(AT)houston.rr.com

In my case I am using a 3.44 diff, a .89:1 4th, 205x15x65 tire and end up at about 2815 RPM at 65mph.....

regards,

Jim

Jim,
Are you driving a T4?

Michael,

no, my engine is a type I/

Jim

Barry,
I use this one.
CBPerformance has a link to it from their home page

http://www.et-studios.com/motorsports/gears/gears.html

GregB

Thank you, Thank you,Thank you ,one and all.

That's what I like to see. Throw a pebble in the ocean, and get a tidal wave. WOW!!

My T-1's final drive ratio is 367.1 What does a 344. gear come out of? or was it custom made? l know the 411 sedan uses a 341.1 but their not to common.

A custom made gear still would be wiser I want it dead on target If at all possible. It needs to work right for anyone that needs a automatic and wants a T-4 pushing it.

With a strong enough engine and my freind Mark's valve body tricks it might even chirp second. Now that would be sweet.

I just sent off a oil pan from a spare today, with my suggested specifcations drawing. Im going to have 4 aluminum pans made with 3/8 aluminum pipes from front to rear. That will help in a hot climate. 2 will be spares

I clicked on the link and saved it to my favorites, Thanks Bill!!

My 2367 T-IV runs 4000 RPM at 80 MPH. That IS cruising speed in southern California!

Mine is a 2056 ,I wont have that much kick.

The gear calulator. came up with 4,000 at 83 with a 3.50 ratio. very close to that. a 3.44 came up oddley lower than that. that makes me queston the accurcey of the calulator.

But with a pencel and pad Im comming up with a 3.44 as very close .to that. and it might be better for my smaller displacement.

What gear and tire are you running? My tire dia: is 24.5

OK 3.44 OR A 3.41 Or which ever the 2.0 automatic 411 sedan yelds.

If we can find one?

KCR wants $750 and Up to make a R&P.
Sounds very expencive.

They said the Automatic is differnent than the straight gear rearend

I have 5 trannys here 4 are automatics one is a SB 4 speed Looks like I got to do some dismantling to get to the truth.

If have to remachine parts to make a set fit At least I will have a clear idea as to what I can or can not do.

Bugtrans.com offers a 3.44 set for the 4 speed .

Going fromm 3.67-1 to 3.44 shouldn't be that big of a deal (REALLY)

And the verdit is the gears have a totally different cut and angle Only if they were made from scratch would it be possible. NOT worth the Cost. in excess of $3,500.
I,d go back and redo the K frame first and narrow the axles and rear track. to make room for taller tires. I went back and recrunched the tire sizes and second and third shifts 25.5 would work perfect, I,d also have to raise the cars ride height to insure they didn't rub the inner wheel well liners .