just purchased a 76 highboy custom 4x4 390.Just finished the exhaust. (totally rotted from headers back). But now I'm onto the clutch. First I'd like to know a decent clutch for under 400 bucks. I've been looking around and not sure if I should go with one off of (so and so) webs site or if I should go with the run of the mill from (so and so) auto store. I'd love to hear what some of you run on these older trucks and ones I should definitely stay away from. My second question is, (as I've never done a clutch, got a mechanic buddy who is going to help me) I'm completely lost with things such as,
Dual Friction, 1 1/16 in. Diameter Shaft, 10-Spline, 11 in. Diameter Disc. Also seen them listed as
Dual Friction, 1 1/8 in. Diameter Shaft, 26-Spline, 11 in. Diameter Disc
Not really sure if 11 in. diameter is correct, 11.5" or even 12" is correct. (so and so) auto store has it listed as a 12". I'd rather have the clutch in hand to install instead of pull and then order. Any help on this would be greatly appreciated.

 

I think I may be able to offer some guidance with your questions.
If you mean a double disc clutch set up they are not that complicated.
Naturally the larger diameter of the clutch pressure plate and disc the more torque and rough application it can handle. There are space limitations as to just how large a diameter clutch the flywheel can accommodate. Most of the time heavy duty truck supply stores can supply what you will need. There is no problem with replacing what you remove with the same size parts. You will need to replace the pilot bearing, intermediate plate drive pins in the flywheel (4 to 6 of them) the pressure plate (release bearing is a part of the plate assy, two clutch discs, intermediate plate, and depending on the condition of the clutch cross shaft maybe the fork assy. You need to know how many splines are on the trans input shaft to get the correct clutch discs with the correct number of splines to match the input shaft. Sometimes depending on how badly worn the input shaft is worn you might have to make a decision to replace the shaft , otherwise the clutch discs can hang up on the worn splines and not completely release resulting in the input shaft not stopping when the clutch is depressed making it difficult to place the trans in gear from a stop. It's heavy work and those transmissions are very heavy and require a special trans jack to do the job right. Hope I clarified and answered some of your questions.

 

yes that did clear up most of the questions I had. just out of curiosity are certain brands (in your opinion) better than others? I've heard LUK thrown around recently by co workers but the price seems low for it to be a higher quality build. I'm not looking for a race clutch by any means, but I do plan on using the truck off road (camping, wood cutting, etc.)

 

Most of the time a heavy duty clutch supplier will carry only one or two brand names and when you get into heavy stuff whichever one they carried was usually OK.
One of the main differences was the way the clutch was adjusted and most of the time we used the assy made by Eaton/Fuller. Spicer was also a common manufacturer. If the clutch assy was installed properly and kept adjusted they rarely gave any trouble. For the amount of money they cost they usually gave you your moneys worth. By this time you probably know starting off in the wrong gear and slipping the clutch can destroy any clutch in short order. You can smell it burning when this is taking place. If you start out in the lowest gear you can let the clutch out fully , minimum slipping, and then apply the throttle .The vehicle will usually walk away while pulling the house down.