Prepping for Primm!!

[84projectFORD]

yeah id think so if you lost all gears at once or did it gradually drop down a gear before all together quiting?

 

[oldgreen]

yeah id think so if you lost all gears at once or did it gradually drop down a gear before all together quiting?

It quit all at once. The truck stopped in the dust behind another vehicle that was stuck. When they tried to move it again. . .nothin'. Ford is saying busted input shaft. We're putting in a C4.

 

[84projectFORD]

It quit all at once. The truck stopped in the dust behind another vehicle that was stuck. When they tried to move it again. . .nothin'. Ford is saying busted input shaft. We're putting in a C4.

The only way to go unless you do a manual

 

[gw33gp]

Something to consider is the C4 only has only three speeds. Is that going to be suitable for all your conditions? Are you going to try to adapt a lockup converter to it? A non-locking converter will most likely develop more heat.

 

[oldgreen]

All good points. . .

We currently turn the OD off and it will hunt between 3rd and 4th gear on the top end because of the drag (no windshield so it is like flying a parachute). We'd much rather keep it in 3rd. The SOHC motor loves to turn 5500 RPM all day long. Also, we use GIGANTIC coolerS and a low stall converter so heat isn't an issue. If it becomes a problem, we'll know quickly with the temp sender in the bottom of the tranny pan.

 

[84projectFORD]

Something to consider is the C4 only has only three speeds. Is that going to be suitable for all your conditions? Are you going to try to adapt a lockup converter to it? A non-locking converter will most likely develop more heat.

using a 3 speed is almost better for off road racing. you mostly never use OD in a desert truck as OD was made for cruising at a low RPM. In a race, your hardly ever cruising at low RPMs.

As oldgreen stated, the bigger trans cooler will more than make up for the non-lock up torque converter. Most Trophy trucks the TH400 in their trucks and i have never really seen an over heating problem with an 800 HP motor infront of it. hell the TH400 in those trucks fully built only cost 5 grand, the motors are 30K + lol

 

[gw33gp]

I wasn't concerned about OD. I agree it should be turned off anyway if you have it. It just seems that having more ratios available would be an advantage to help keep rpms in a narrower band (power band). That is my road racing experience showing though. It may be that you don't need more ratios in off-road racing. With a three speed you will now probably be mostly hunting between 2nd and 3rd. 2nd will be lower than the 3rd you use to use a lot. Will it be less than an optimum gear? Your rpms will be changing up and down more now during the shifts.

I know little about off-road racing but love to drive off-road.

 

[oldgreen]

We'll be shifting manually from now on. . .reverse manual valve body. In the rough we'll be in second gear and we'll kick it into high for the light chop and graded sections. First gear down the canyons. That's the way we'd LIKE it to have been. If you look at the gear ratios on the 5R v. the C4, 1,2,3 are basically the same.

Here's an interesting thought. When our tranny was going out in Henderson, it wanted to stay in 2nd gear but would pop into 3rd or 4th if you were really careful and feathered the throttle but as soon as you got back on it it would dive back into 2nd. As it turned out, it would have been MUCH better to have been stuck in 3rd gear. Top speed in 2nd is under 50mph and even though we use 2nd in the rough, 3rd would have been better all around. Especially with the 4.88s. It is good from 35mph all the way to almost 90mph in 3rd gear. At the slower speeds, it is a dog but it still works. . .but now we'll be able to bump it down into 2nd at will. . .like a real race car.

 

[gw33gp]

Sounds like you got it figured out. That is one thing that makes a good team.

I don't know a lot about automatics but think I had a C4 in my 68 Fairlane 500. I beat on it pretty hard and never had a problem with it. I could manually drop it into second at any speed and did so once in excess of 100 mph. That is not good for the engine or the transmission but I was young and stupid and everything survived. First gear on the other hand would not manually down shift unless I was below a certain speed. Is there anything you can do to over-ride that safety feature or do you plan to keep it that way? Maybe the reverse manual body will take care of that.

 

[oldgreen]

The valve body will take care of that issue. The old tranny is ready to drop. . .tonight is the night we diagnose what went wrong.

 

[Jim Oaks]

Can't wait to see what it was.

 

[84projectFORD]

so what was the culprit and have you got the C4 in yet? Vegas to Reno is commin quick!

 

[oldgreen]

Update:
Hard parts of all kinds failed and a planet welded itself together: No Bueno

c5/c4 w/reverse manual valvebody is in and running strong. No problems at Vegas to Reno. It went 706 miles without a problem but we blew the motor on the last day. The good news is that you are allowed to DNF one day at V2R and still finish the race so we got 3rd in class!! The new tranny is awesome and if you guys want to put a SOHC 4.0 in front of a C4, we know how!!! We did NOT use the high dollar Culhane flexplate either.