1951 F4 loses power in 4th gear?

[GregTX]

While driving my F4 my truck loses power. I can only drive in 2nd or 3rd gear. Do you guys think this would be a clutch problem? I have had the truck for a year or so and am not sure when the clutch, pressure plate, bearing was last replaced.

I usually take off in 2nd gear. I notice when I shift to 3rd and 4th the gears seem to grind a little. This usually doesn't happen. When I stopped and shifter back to 2nd, the flywheel seems to be spinning still because it grinds quite a bit.

I know a good mechanic who bleeds Ford blue and knows quite a bit about these classics, but I wanted to hear what you guys think first.

Thx!

[corvette8n]

Sounds like you have more than one issue here, you need to trouble shoot one thing at a time. Put the truck in 4th gear rev up to about 1500 rpm let out the clutch slowly if truck stalls your clutch is not slipping. Grinding gears could be clutch not releasing or bad syncro gears in tranny. When you say it feels like it is losing power do you mean the motor is reving up and you are not going anywhere or the motor is slowing down?

Nice looking truck.

[JSeery]

I thought all 4speeds grind when switching gears (unless you are really good and matching engine speed to transmission speed).

[scooder]

Welcome to the Barn, I really like your truck, beautiful.
I agree with above, especially the question regarding your loss of power, is the engine dying or revs climbing but truck not going faster?
Don't recall if there synchronised four speeds in your truck?
Mac Vanpelt clutch test, start the engine, put your hoof on the clutch, count slowly to twenty, try to engage first gear. If you get a grind, the clutch ain't releasing properly, could be adjustment (1 - 1 1/2" free play at the pedal depending on information source) or contaminated clutch disc requiring replacement.
Measure your pedal free play. And let us know.
Martin.

[B-O-B]

Do you double clutch when shifting up or down & when down shifting do you rev the engine any?

[47 flatbed]

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Nice ride. I drive my tonner almost everyday to the shop and appointments. I have the same 4 SPD crash box. I've had to learn double clutch and speed matching gears. I enjoy the challenge.

[GregTX]

Thx for the quick responses

corvette8n - The rpms climb, yet the truck begins slowing down.

I double clutch when shifting. I haven't mastered shifting without using the clutch.

Scooder - I will measure the free play when I get home this evening.

To be a little clearer when I shift I always get a little grind. However, when I started having issues the other day the grinding was more intense. I almost had to jam the truck into 3rd gear from 2nd. From 3rd to 4th it slips right in, but that's when the truck begins to slow down.

[WestCoast]

if rpm,s climb when driving and truck slows down, I bet the clutch is bad, unless the free play is wrong,, you need about 1 to 1 1/2" free play, if its less than that the clutch is adjusted to tight and letting the clutch slip on the fly wheelpush clutch down with your fingers, when clutch lever quits moving using your fingers measure the free play

[GregTX]

Sorry for responding so late. I have been out of town.

My issue is definitely the clutch. Before I remove it I want to go ahead and order the kit (clutch, bearings, pressure plate). can you guys confirm the original clutch size is 10"? Most of the sites (RockAuto, Summit, etc.) list it as 10", however, I found a couple sites offering both an 11" and 10" for this same setup (239cid/manual 4 speed).

Thx!

[glennsanders]

Your 4 speed is probably set up with 11 clutch ,you have to change flywheel are have drilled and tapped is using 10.big truck go with 11