Can you damage the tranny by re-rating the engine?

[tracer]

The engine is 435 hp 1,650 Cat C15. The clutch is rated for 1,750 lbs of torque; and the 13 speed transmission (overdrive; 0.73 top gear ratio) is rated for 1,650 lb/ft of torque. Everyone has different opinions, so I decided to ask here: if I re-rate the engine to 475 hp, and MULTI-TORQUE of 1,650/1850 lbs - can I kill the tranny? Note: 1,850 lbs/ft of torque will only be available in the top 2 gears. Gear ratios (transmission): 7 high - "1"; 8 low - "0.86"; 8 high - "0.73". Local CAT dealer refused to do the re-rate, but a International dealer was quite willing ... only they asked for a big fee. What do you guys think?

I"m pulling dry van trailers between North-East and Canada and will be shortly switching to flatbed trailers.

[TK THE TRUCKER]

My opinion is with that scenario, driven smoothly, I don't think anything would get torn up. Your not exceeding the rating by a whole lot. If you have any warranties left it might mess with them or void them completely because technically you would be exceeding the ratings. You may go through all this time and money and not see the increase you were hoping for. If you go through with it let us know how it turns out 8)

[solo379]

I've done that with my old truck, from 455/1650 to 550/1850, same tranny and clutch as yours, sold my truck with original clutch and all drivetraine, at 962,000.
And though the new owner has to replace clutch shortly(at about a 1,000,000 miles) he did run another couple hundreds K w/o any problem, than he sold the truck, and I've lost track of it! :sad:

Just take it easy! And you gonna feel that extra torque, could also gain some MPG, with the proper technique! 8)

[PhuzzyGnu]

Drivers damage transmissions, not engines.

-p.

[PackRatTDI]

The only risk is that any damage won't be covered by any warranty.

[brian]

i`m several hundred pound feet of torque over my 18 speeds rating and it shifts like new

[Kranky]

If you drive it smooth it shouldn't be a problem.

If you (or anyone else) start jamming it in gear at the wrong RPM, or otherwise abusing it, the tranny will be history. But that would be the case even at the stock HP/ torque rating.

[tracer]

Drivers damage transmissions, not engines.

-p.

Well, one International dealer I went to was ready to do the rerate, but they mistakenly quoted me a wrong price (the one CAT charges on trucks still under the factory warranty). Then I went to TOROMONT CAT and they refused to re-rate the engine. Their argument was they had a guy who had his engine rerated and then lost the transmission, so the guy sued them and the court agreed to make CAT pay. So at least this particular dealer is no longer re-rating engines unless all driveline etd components can take the additional torque

[solo379]

a guy who had his engine rerated and then lost the transmission, so the guy sued them and the court agreed to make CAT pay.

What a joke! :twisted:

[special k]

You're out of luck with Toromont I went through the same thing 6 years ago with them. Got the same story I doubt it's even true. I had to upgrade my clutch because it was a 1650 clutch with an an 1850 trans and 1810 driveline. I wasn't impressed luckily the gasket between the belhousing and the motor started to leak and it was covered under warranty so I gave them a new 1850 clutch and they paid for the rest.

[yoopr]

You can also lose your warranty if it's still under Warrantry

[PackRatTDI]

Drivers damage transmissions, not engines.

-p.

That's been Pittsburg Power's experience. They've built 700hp NTC monsters with 1800+ lbs/ft that are still spinning through old RTO-12513 transmissions with no problems. But in that case, you don't risk any warranty (unless the transmission is a warrantied rebuilt/reman unit).

That is correct i had a 444 rebuilt to a 720hp+ to the Ground measured on a dyno going thru a stock 13 double over and a set of 3.55 gears and I never once blew either the clutch trans or a rear end. Now the one time I was out of the truck when I had my appendix out the boss put a BBR in her and he managed in a week to tear the power divder and rear rear end out all at the same time I have no clue how he did it either.

[allan5oh]

I don't know, trannys are rated for a reason. To be honest I don't think they care much about final torque, they care about torque from the engine. More torque means more stress, and even though they have two countershafts, you can get some serious deflection in the transmission.