Hemi TC Vs Suncoast?

yakers · **Posted:** Sat Apr 04, 2009 2:13 pm

I saw an earlier LostKJ thread and could not find it on a search, that the 'new' Hemi TC will fit into the CRD and it appears to be a better product than the original CRD TC. That is not saying too much, the question is whether it is improved enough. Does anyone have this TC? How does it compare to the Suncoast for durability, price, availability and the like? I tow a 3,500lb travel trailer occasionally and I am contemplating a Suncoast TC but wold just as soon go with a Chrysler product if it costs less and would probably be a more 'normal' install. How do I get more info on this TC? I assume there is plenty of experience with this TC in a Hemi if that tells us anything about how it would function in a CRD.

Joe Romas · **Posted:** Sat Apr 04, 2009 6:04 pm

I'm sure you'll get more responses but I understand this is the torque converter Sun Coast modifies for our CRD's. As is I doubt that it would work well on our CRD's because it's setup for a hemi that has different torque bands then ours do.

truckbouy2 · **Posted:** Sun Apr 05, 2009 6:02 pm

Stall speeds are different.

yakers · **Posted:** Mon Apr 06, 2009 11:29 am

Thanks, I guess I read that other thread wrong. So Suncoast coverts the hemi TC to work with the CRD, the stock hemi TC is not a direct alternative item for the CRD. Just looking & wishing for options.
I'm probably going to need a Suncoast TC sometime ( I sometimes two a 3,500 lb travel trailer) but I am trying to figure out if I can wait a while or if I should do it now to prevent problems. 52K miles and no problems so far, do have Provent, new filter head, and inactive EGR. Only three thing to go; install the SEGR, fuel pump and the Suncoast. But when things are working well I'm tempted to leave them alone.

yakers · **Posted:** Mon Apr 06, 2009 11:30 am

Thanks, I guess I read that other thread wrong. So Suncoast coverts the hemi TC to work with the CRD, the stock hemi TC is not a direct alternative item for the CRD. Just looking & wishing for options.
I'm probably going to need a Suncoast TC sometime ( I sometimes two a 3,500 lb travel trailer) but I am trying to figure out if I can wait a while or if I should do it now to prevent problems. 52K miles and no problems so far, do have Provent, new filter head, and inactive EGR. Only three thing to go; install the SEGR, fuel pump and the Suncoast. But when things are working well I'm tempted to leave them alone.

yakers · **Posted:** Mon Apr 06, 2009 11:31 am

Thanks, I guess I read that other thread wrong. So Suncoast coverts the hemi TC to work with the CRD, the stock hemi TC is not a direct alternative item for the CRD. Just looking & wishing for options.
I'm probably going to need a Suncoast TC sometime ( I sometimes two a 3,500 lb travel trailer) but I am trying to figure out if I can wait a while or if I should do it now to prevent problems. 52K miles and no problems so far, do have Provent, new filter head, and inactive EGR. Only three thing to go; install the SEGR, fuel pump and the Suncoast. But when things are working well I'm tempted to leave them alone.

yakers · **Posted:** Mon Apr 06, 2009 11:40 am

Sorry for the triple posting. My browser indicated an error (Failed sending email :: PHP ::

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So I assumed that the post did not go through and resent it.

truckbouy2 · **Posted:** Mon Apr 06, 2009 12:38 pm

I wouldn't be too quick to be turning to suncoast (and they have a wonderful product) until you have too. With a little knowing how to drive these little experiments I think you will get long life out of the stock TC.
I trained in "The Princess" to leave OD locked out around town (that's up to 60 mph) thus keeping the rpm's up and pump pressure up. Nothing is worse for the transmission (the engine too) than low end low rpm lugging.
"Yes but that will hurt my fuel mileage" Yup, it will. But then if you bought a Mopar product for dazzling fuel mileage....You got bamboozled.
She's driven the little oiler like that from day one and there has been no transmission issues pulling or running bobtail.

jinstall · **Posted:** Mon Apr 06, 2009 6:02 pm

I have been doing the saem but now I drive in heavy DC traffic and started to nitice some noise coming while in gear at idle. I am wondering if this is the sould of the TC letting me know I need to order a new TC.

nmCRD · **Posted:** Mon Apr 06, 2009 8:38 pm

yakers wrote:

Thanks, I guess I read that other thread wrong. So Suncoast coverts the hemi TC to work with the CRD, the stock hemi TC is not a direct alternative item for the CRD. Just looking & wishing for options.
I'm probably going to need a Suncoast TC sometime ( I sometimes two a 3,500 lb travel trailer) but I am trying to figure out if I can wait a while or if I should do it now to prevent problems. 52K miles and no problems so far, do have Provent, new filter head, and inactive EGR. Only three thing to go; install the SEGR, fuel pump and the Suncoast. But when things are working well I'm tempted to leave them alone.

I think what you are looking for is in the CRD TECH ONLY section.
It is under Sticky: Haystack currently the last post posted

http://www.lostjeeps.com/forum/phpBB3/vie ... hp?t=30576

yakers · **Posted:** Wed Apr 08, 2009 12:58 am

Can someone explain how 'stall speed' works here? Is it that the transmission does not want to slip at idle? Would it matter that the CRD is cruising at a low RPM for the engine? For top fuel mileage the theory is to go 60 or even 55 MPH in 5th, would that be a problem with a hemi/Suncoast TC? I would have thought it would 'grab' more so low RPMs would be fine in gear but maybe a problem when stopped, it may be better to shift into neutral at stops. Anyway, I really don't get the gearing/stall speed issue and would like to understand it better. I don't want to replace one problem with another.

ATXKJ · **Posted:** Wed Apr 08, 2009 2:42 am

When you're talking about 55-60 range - Stall speed isn't really an issue - it's close to locked up on anything that'll fit - and the transmission control module tells it when to mechanically lock.

Stall speed is much more of an issue when you're accelerating - a high stall speed has the engine running higher ~2000+ rpm while it's accelerating.
i.e. you step on the pedal - the engine rev's to 2000 rpm and stays there until the Jeep accelerates to match, like a slipping clutch.

a correct stall speed would keep the engine closer to it's torque peak ~1800 while accelerating -
correct stall speed and correct TCM programming would allow it to mechanically lock up ~1800-1900 rpm so you can use all of the torque.

now lower stall will be more efficient and transferring more torque at idle than a higher stall speed.

(FYI on gassers with high rev cam's -peak torque is 4000+ rpm so you want a high stall speed to allow the engine to rev easily)

Joe Romas · **Posted:** Wed Apr 08, 2009 6:45 am

yakers wrote:

Would it matter that the CRD is cruising at a low RPM for the engine? For top fuel mileage the theory is to go 60 or even 55 MPH in 5th

These were about the original figures for lock up in 5th before they started the "Flash of the month" club for our TCM's and the "F-37" customer satisfication bulliten :roll:

nursecosmo · **Posted:** Wed Apr 08, 2009 7:12 pm

yakers wrote:

Can someone explain how 'stall speed' works here? Is it that the transmission does not want to slip at idle? Would it matter that the CRD is cruising at a low RPM for the engine? For top fuel mileage the theory is to go 60 or even 55 MPH in 5th, would that be a problem with a hemi/Suncoast TC? I would have thought it would 'grab' more so low RPMs would be fine in gear but maybe a problem when stopped, it may be better to shift into neutral at stops. Anyway, I really don't get the gearing/stall speed issue and would like to understand it better. I don't want to replace one problem with another.

Stall speed is the point at which the RPM can go no higher with the accelerator to the floor and the wheels locked by the brakes. Like ATXKJ said, It means nothing when the torque converter is locked up, but is most evident at a stop light. Most auto manufacturers do no put the most efficient stall speed TCs in their diesel vehicles because a low stall speed TC creates more stress on the drive train as well as increasing NVH.

chrispitude · **Posted:** Wed Apr 08, 2009 11:17 pm

Hmm. I seem to recall the Suncoast is supposed to have a stall around 1800rpm. My Suncoast allowed the RPMs to go higher than 1800rpm when accelerating even at half-throttle. Can any other Suncoasters report in?

- Chris

nursecosmo · **Posted:** Thu Apr 09, 2009 12:31 am

chrispitude wrote:

Hmm. I seem to recall the Suncoast is supposed to have a stall around 1800rpm. My Suncoast allowed the RPMs to go higher than 1800rpm when accelerating even at half-throttle. Can any other Suncoasters report in?

- Chris

Stall speed doesn't prevent the RPM from going past the stated RPM. Stall speed is the greatest speed difference allowable between the engine output shaft and transmission input shaft speed, after it goes through the TC.

Example: if the vehicle is moving at 30 mpg and the transmission is spinning at 2000 rpm in 2nd gear, the engine rpm can spin up to 4000 rpm if the TC stall speed is 2000. If the stall speed is 1500 rpm as in the Suncoast, then max engine rpm will be 3500 at full acceleration.

chrispitude · **Posted:** Thu Apr 09, 2009 10:47 am

Thank you nursecosmo! I finally understand the stall speed concept now. Much appreciated.

- Chris

Hemi TC Vs Suncoast?

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