I believe the gents at South Bend are refering to the improper method of downshifting by not synchronizing RPM and driveline speed. When done properly your RPM should drop by 500 RPM approx. when shifting up and should increase by same amount of RPM when shifting down. If you have 300 HP shifting up and your E brake has 190 HP hold back when shifting down and you synchronize properly there will always be less torque slowing down on your driveline. Dumping on the downshift is equivelant to riding the clutch to get moving instead of fully engaging clutch and then roll on the power. Smooth attentive driving technique will allow one to haul many heavy loads with big power and minimum of repairs. The big boys did this for years as they ran cranked diesels long before the manufacturers produced brutal drivelines, a lead right foot usually means extensive mechanical experience.

 

Yup.. If'n you're in 2nd going up the hill, you better be in 2nd going down the hill. I drive a 4.6L gasser, auto. I use the shift lever. Guess the guys with the new GM and Ford don't have the smarts to do this, so they need "tow haul" mode. If'n these guys were smart enuf, they could do that by pulling on the lever.

 

Thankyou for the input, South Bend Clutch, and I was not trying to degrade your product in the least. I run heavy, every day and downshift on all slow downs. On some larger hills the engine will sit near 3000 for some time with now and then a help from the brakes. I do shift smooth and always match the engine speed with a double clutch shift. I have the five speed and managed 126,000 on the stock clutch. Never have had a problem from the five speed yet.

I now have a Luk Pro Gold and the truck has 154,000. The U joints are original which should be a reflection of proper driving with the weight that I pull. The original brakes on the trailer have almost 100,000 and the truck brakes have had two pad changes and two shoe changes in the rear. Neither the disks nor the drums have been turned, although that will come with the next change. This is without an engine brake. I am careful with the shift points.

The original clutch did tear out the center but the pilot bearing went out first which was part of the cause. The pressure plate was reuseable as was the friction surface. Driven properly the drive line is quite strong. I have been able to live with it. I have the large input shaft six speed to put in soon and then it will get the strongest clutch that I can get. And I am sure that it will be the SBC.

 

Double clutching - :-[ Without looking too stupid (ok, too late for that) how do you do it?

 

Guess us old pharts who learned to drive b4 synchros only know. How do you explain this??? B4 synchros? What's that mean? Hehehe.

 

ASFMSgt as long as your driving a synchromesh tranny you will never need to learn, find your RPM split on the upshift and reverse it for the down shift. Double clutching is the taught method of shifting a NON-synchro tranny with straight cut gears. Start by finding shift point push in clutch take tranny out of gear to N push clutch in again put into next gear, basically 2 clutch movements 1 gear change. Reverse this along with down shift method stated before and you have it built--- theoretically of course, perfecting this with a real 9,10,13,15 or 18 spd takes a little more time. Start adding a second tranny and you can really have some fun. PK

 

Very close to 75000 miles on my truck now....amassed in 18.5 months. As an oilfield operator, I probably start and stop close to 100 times a day counting all my leases, stop signs etc.....at the last tire install approx. 3000 miles ago my brakes are still very close to new all the way around. Secret?-E-brake since almost new, combined with careful downshifting (blip of the go-pedal to match the RPM up close) and decent driving skills (ie. why fly up to a corner that you know is there when you can accomplish the same thing coasting up nicely without using your brakes)........Assuming I don't see a catastrophic failure such as delamination of a pad I expect to see well over 150000 miles on the stock brakes assuming I don't get a wild hair to upgrade them to Carbomets or something similar before then! <br><br>I drove professionally for 6 years before I had this truck-hauling crude oil, condensate and produced water around the oilfields of Alberta in a 6 axle truck and full trailer combo grossing in over 110000 lbs.....teaches you a lot about anticipation, planning and patience. Also learned the art of clutchless shifting with a Roadranger from this gig-all the left pedal got used for in my truck was starting out and engaging the PTO...... ;D Still have to slap myself once in a while when I find myself trying to shift the Dodge the same way.....<br><br>Jason<br>

 

Wow... you guys do have alot of information. Thank you for your responses. What I'm taking from your replys is that downshifting is alright (just as my Dad taught me years ago), as long as you sync up smoothly and properly before letting the clutch engage entirely. <br><br>I know that most of you guys were talking about bigger trucks and pulling heavy loads. With my 2500 RAM, Cummins, are we not talking about a different (smaller) clutching system?<br><br>Don't get me wrong... my plan after reading your replys is to downshift to start the slow down process and apply brakes as I come closer to the stop. I'm reading that this is OK and will not put wear and tear on the clutch pad and safe on the wear of the brake pads. <br><br>Thanks, I'll be watching for more of this and other topics,<br><br>EvKar

 

JHansen, I Learned to drive with 36 Chevy truck, four on the floor. Shortly after taught myself clutchless upshifting. Transfered that skill to to dad's 41 Chevy columnshift 2dr, later to my own 35 Ferd 2 dr 3 on the floor. Dad was a conservative driver learned from him lots about proper shifting an braking. Then taking physics in HS and University, the Laws of motion and combined forces, it is easy to apply these to driving. Saves unnecessary wear and tear on vehicles.<br><br> ;D

 

[quote author=SeaRay88 link=board=11;threadid=6817;start=15#66975 date=1037325043]<br>Guess us old pharts who learned to drive b4 synchros only know. How do you explain this??? B4 synchros? What's that mean? Hehehe.<br>[/quote]<br><br>Hey just because I have not hair or teeth and remember the second WW, you gotta call me an &quot;old phart&quot;? ;D ;D

 

Learned to double clutch driving tractors on the farm at 12 years of age. Their trannys non-synchro. Sometimes had to take amnure and spread in in a field 1/3 mile away from pens. Always wet enough to be heavy. Had to start in 1st gear to get the load rollin. Once it was rollin had to shift to 3rd directly by double clutching. Then you could travel at 15 mph to where it was to be spread. Anyone that worked at that job all day smelled like an, &quot;Old F__t&quot; for sure. We always gave that job to the new guy on his first day at work. We also gave explicit instructions to spread the manure as fast as possible to keep ahead of the aroma. When he would retern from first spreading run his backside would be covered with, you guessed it, manure. Kinda got initiated into the job on first day.

 

Well, that's the exact same thing the dealer told my dad bout his vette. We blew the 2 and 3 gear synchros, and cones, and chipped a couple of teeth. He said it was from improper downshifting(apparently it doesn't like to be thrown from 5 to 1 at 35mph : Go figure). We needed to rev the engine real quick before putting it in gear so there's not as much wear and tear on them. He also said you can't speed shift the thing cause of the way the tranny is set up. Go figure. You buy a vette to hot rod and you can't even do that cause the tranny can't take it. Oh well.

 

Maybe I can explain what you are doing when double clutching. This seems to be a problem with some. When you push in the clutch, the clutch disk and transmission input shaft are turning at the speed of the gear you are in. When you shift, the syncro’s which are like a simple brass clutch, have to make the speed of the clutch disk and the shaft the same speed as the next gear. Then the clutch has to correct the speed of the big diesel to the speed of the gear that you just selected. If just pushed into gear it can be rough on the both the syncro’s and the clutch. <br><br>You come to the top of a hill, and need to select a gear that will put the engine up near 3000 rpm to slow the truck. You push in the clutch, pull the lever to neutral, let the clutch out and speed the engine, the clutch, and the input shaft to near 3000. Then you push the clutch again and put the transmission in the correct gear. The goal if done right is that the engine, the clutch disk, and the input shaft of the transmission are all turning near the same speed as necessary with the new gear. Doing it this way there is not great load on either the clutch or the syncro’s.<br>

 

Hey, Peter from SBC, thanks for your reply here. I thought a flame might have been coming. My last straight shift had over 150K miles on it before the clutch started slipping under load (towing). I don't have a SBC but intend on replacing my OEM with a SBC when I need one. I don't think his article or reply was negative. I do think it was factual. The article was one of the best I've read in quite a while and had good points about replacement do's and don'ts. Again, Peter, since you wrote the article, my hats off to you. Good job and thanks for the information.