CAT 7155 Manifold rebuild

[R Racing]

It has 4 layers of aluminum and 1 of steel. 3 of the 4 aluminum plates are hard anodized. but this 1 had nicks and gouges on some of the surfaces before I stoned them flat.I truely wonder if it was a contrator deal were they did a quick coat of paint and turned them loose. I will say that all but 4 of the O rings are the newer style 1s of a newer rebuild and so were the style of gaskets.

 

[Seatyger]

Thanks for taking the time to share your knowledge and take the photos. Im as dumb as a sack of hammers when it comes to trying to 'visualize' from the written word alone! The manufacturers should be required to be Members of this site. They could learn a lot about effective presentation prior to completing their manuals!

Keep up the good work!

 

[Coldfusion21]

Who knows? Maybe they fished it off the bottom of a stack that sat in a puddle. Seeing that it was messed up, repainted it, and put all new plugs in the ports. What kind of material is the manifold milled from?

Curious as well, some shots look to be aluminum but your latest pics look like steel.

Must have been quite the job at the time machining all those bores out and such...

Edit: missed the last page! Thanks R Racing

 

[putz273]

After story

So how did it turn out? Was the rebuild a success?

 

[R Racing]

A resounding yes !!! I rebuilt both the 1 in my m920 and m917 and several more for Cat.

 

[Nonotagain]

A resounding yes !!! I rebuilt both the 1 in my m920 and m917 and several more for Cat.

Jim,
You were missed at Aberdeen this year.

Hows things going?

 

[R Racing]

Hi Greg !

I so wanted to be there. but work and lack of funds kept me from attending I'm Praying Things turn around.

 

[kb1122]

Hi guys i just rebuilt my first cat 7155 manifold found nothing wrong with it but alittle muk in it but i replaced all the orings and cleaned it up bench testing it works fine any sugestions b4 i put the trans back in. I live in upstate ny and no one up here works on these that i can find.

 

[putz273]

Cat 7155 Zen master

R-Racing is the man with all the info bout Cat 7155 im him and he will reply. He has done several trannys with great success. He understands these better than anyone I've ever talked to. IMO

 

[R Racing]

ok several things come to mind here. 1 did you pull the trans or take it out the top thru the floor ? 2 how did you bench test it without launching the shift actuator pistons, and how did you test it ? and how long? 3 did you rebuild the all of the shift actuating pistons ( espically the 3 spring loaded double sided units ) 4 what is the air pressure output from the manifold regulator to the output clutch in every gear? 5 did you tourque all of the manifold bolts and actuator bolts and what did you tourque them to? 6 did you check you quick fill curcuit and valve ? 7 did you have any air leaks thru any of the vent ports or anywere else ? 8 how was the flatness of your bottom and top plate of your output regulator?

 

[Monkeyboyarmy]

opcorn:

 

[kb1122]

I removed the trans from the truck. I did replace all the orings in the piston acuators including the spring loaded ones. I tested it by puting it back on the trans hooking up a regulator and a air line aswell as the shifter and set the reg to 100 lbs. The only thing i did not replace in the manifold was the popits only because i didnot have the tool to do them but they looked ok. When i went to southworth cat they said good luck and no they cant get the tool. Thats the only thing that makes me nervous is not replacing them.

 

[R Racing]

Ok Boys and Girls time to brake out the sharp #2 pencil LOL.

since you have the trans out , Its the perfect time to check your flywheel bolts . When some of these trucks were rebuilt. Bolts that were a inch to short were installed and were not torqued correctly causing the flywheel to come loose and damage the trans.Ask me how I know !!!!

Ok the 100 PSI is the incoming pressure. I need to know what the output pressure from the regulator thats built in to the manifold is putting out in every gear it will change every 4 gears and start at about 90 PSI and in the upper gears be as low as 22 PSI . I'll see if I cant find a picture. The port is to the right and below the regulator block on the manifold.sometimes there marked clutch. and you have to remove a 1/8 pipe plug and install a gauge in there.

Actuating pistons. Did you replace the O" ring between the 2 chambers way down in the bore as well? its about .5 ID and about .87 ish OD going off of memory. Its very important you do.

I made the poppet tools myself. If there in good condition there is no reason to change them as they are very durable.

 

[R Racing]

Here is the picture of were the output clutch air port is in conjuction with the manifold regulator.The gauge reading 40 PSI is were you need to check it at.The big green block on the manifold it the rear output air regulator. This controls the air pressure to the rear clutch. It is internally adjusted with shims.

 

[kb1122]

Thank you RRacing that puts me in the right direction i really want this trans to work correctly the guys at work told me to put a fuller 13speed in it if cat wont fix it. lmao now that i have the trans out they have nicnamed it the beast. We have done transmtions b4 but this is like nothing weve ever seen. We use it to remove snow and is very important to us. There was also 2 plates bolted around the top and bottom of the manifold with 4 wires going to them i think they are warming plates can i leave them out. And again thank you

 

[R Racing]

Yes those are heaters. If you plan to run a filter system with a water seperator and lube mister than you might be able to get away with not using the manifold heaters. If not the problem is any moister can freeze in the manifold and shut you down.if you do add those to the system it should be mounted to the rear of the passanger side air tank.

 

[kb1122]

I will be testing the presure at that port today. I was able to find how to test it in the manual after reading youre post. I did replace all the orings in the accuators and the ones on top of the popits. I have went to the local heavy duty parts place bought a filter and oil mister. Thanks again

 

[kb1122]

Ok so i tested the rear clutch pressure and it was on the money threw all the gears going by the manual. I did also notice that the number 10 vent was removed and there was a pipe plug in its place i believe its for the rear clutch i removed it and the pressures are all the same. Also i uncoverd a plate on the side that says overhauled at tead 6/91 mwo applied 9-2520-277-35 6/91 would they have pluged that vent for a reason? AGAIN THANK YOU R RACING

 

[kb1122]

Trans works great we installed it last week and have been test driving it evert day. Again thank you Rracing for youre help.

 

[R Racing]

Glad I could help