Exhaust brake without lockup trans

[AndrewKing]

HI All,



I was wondering if an exhauset brake can work with auto trans without lockup (have a DTT89TC so it's a little tighter and lots of transmission cooling (B&M finned alum pan adds 2 qts and a 40K rated Tru Cool transmission cooler in addition to whatever the factory has on it)... . I realize that it is not as good as having a lock up transmission or stick but isn't some engine braking better than none if I just watch the trans temp guage?..... Just curious but I have heard that Jake Brakes are often rated as to their retarding HP equivalent... . How much retarding HP does an exhaust brake offer?

Thanks for your help.



Andrew

 

[jcarey]

Andrew, I think response #5 in the following thread is your answer:



https://www.turbodieselregister.com/forums/showthread.php?t=120279



Jim

 

[cwsoules]

Before I got my smart box there was a brief time when I had an exhaust brake alone. I went on I-5 over the grapevine towing my 5th wheel. I found that with the brake on and the truck in cruise control the exhaust brake provided retardation on slight down slopes. Above 6% slope the weight of the 5th wheel would cause the truck to accelerate, the cruise control would unload the transmission and I would be left with brakes alone to control speed. It sort of helped, but it is the steep slopes where you want and need the exhaust brake. I was happy when my smart box was finally installed. You definately need a transmission temperature gage and to watch your tach when towing without a positive lock on the transmission. When the tach drops to idle I'd turn off the exhaust brake.

 

[Sarge]

There is a condition known as "fluid shear" that occurs when you use an exhaust brake with out lock up. The transmission fluid actually boils and distroys the converter and clutch plate. Not worth the chance. Get the lock up kit if you put one on. BTW, that is the very reason why DC has held off approving an exhaust brake for the auto trans.

 

[AndrewKing]

Thanks for the help guys... ... from the sound of it, the little I may gain may not be worth the extra cost of the brake itself..... A friend of mine upon reading this suggested rigging a bed mounted wing that is adjustable via motor so that it forms a wall when additional aero drag is needed to slow down or remain in a normal wing position in normal driving to reduce aero drag..... Is there anything like that available now?... . kind of an airbrake of sorts?

 

[Joe G.]

If you want to spend the money you can put a 47RH trans (stock in '94 and '95) in your truck. I'm not sure of all the parts needed. It's longer in the TC area so a different adapter is needed. Basically, need the parts off a '94 or '95. I think the flex plate is different too. Cross member. Drive shaft. I think it's not really reasonable thing to do for a '93. If you tow a lot it makes more sense to get a later truck.

 

[JGarcia]

Seems like your best bet, operationally and cost wise, would be to install the smart controller from DTT since you have the TC already. Exhaust brake is a great thing to have!

 

[Joe G.]

JGarcia,



A '93 does not have a lockup TC. That's the problem. The smart controller will only work with electronic controlled transmissions, 47RE and 48RE. The 47RE was first used in the '96 model year.

 

[WestTN]

The Jacobs exhaust brake delivers 190bhp in a 2001. This occurs at maximum engine RPM.



I notice your truck is a 1993. You may need the heavier vavle springs to safely use an e-brake. I don't remember when they became standard equipment. They're called 60lb springs.

 

[jelag]

With the slippage of the automatic without some means to lock it up... I don't suggest an exhaust brake to customers... . the ability of the engine to absorb the energy isn't in question... you can't pass that energy to the engine with a transmission that slips... . no matter what you do to cool it... . I have some customers that come and see us after they have had some other installler hang one on their truck. . thinking there is something wrong with the exhaust brake... . I have to sit there and explain there is a clutch in the transmission that is slipping and not allowing the engine to do any work...



As I remember all 2nd generation trucks have the higher pressure exhaust valve springs... but I'm at home and don't have access to a catalog for that information... . the real issue here is that without the lock up... the transmission slips... overheats and won't pass the energy on to the engine/exhaust brake... .

 

[Joe G.]

Jim,



I think all the 12 valve engines have 35 lb valve springs. Later engines have 60 lb. Piers sells the 60 lb at a good price.