GMC conversion Clutch Hydrolic problems

[RyanB]

GMC conversion Clutch Hydrolic/Electrical problems and Questions

Alright guys... here is a conversion question I have never seen before on here and hopefully someone can help me out!



I finally have my truck up and going but I am having clutch issues. For those that are not aware I swapped in a 12valve, 6speed and a Haisleys Comp Dual disk clutch.



My problem is that the hydrolic lines are bled and have no air at all... my clutch doesn't disengage untill the pedal is 1-2" from the floor (thats almost where the presure starts too!)



What I am thinking is that my GM master cylinder is way to small for the 97 Dodge Slave I have on the transmission. I have looked at the master on my brothers 97 Dodge and his is almost 2x's the diameter of what the GM unit is.



I am 100% sure this is my problem and have no idea what to do other than fabricate my firewall to exept the Dodge Master cylinder. If this is the direction to go in I will be getting one of the South Bend HD units with the quick disconect.



Also, I am having a few issues with wiring up my stock guages and my Alternator.



I am running a Dodge Alternator and had it built with a tach wire and also an external regulator. If anyone has used the Dodge ALT and wired a tach wire did it work right? for the life of me I can't get a signal... . maybe I have the wrong wire going to the dash (white wire... there are 2 lone white wires and can't figure out which one... anyway of testing them?)



Also, my Temp guage is acting strange. I ran the single GMC temp sensor wire to the Dodge sensor on Cummins (back of head... drivers side) and although it works, I think it rises twice as fast as it should and pegs out in no time when its still cool but some heat getting to it.



Anyone else ever experianced any of these please let me know... . RyanB



Here is a sneak peak of my engine (trying to get some wiring isues/clutch problems figured out and make my battery holder before I put my twins on!)

 

[FordCummins]

Get a GMC temp sender. That way you know the sender and guage are working together correctly. Id also get a good aftermarket Oil Pressure and Water Temp gauge. Factory gauges usually arent the greatest.

 

[RyanB]

Get a GMC temp sender. That way you know the sender and guage are working together correctly. Id also get a good aftermarket Oil Pressure and Water Temp gauge. Factory gauges usually arent the greatest.

I have heard of the GMC temp sender but wasn't sure about that. Is it the same size as the cummins unit? also... I take it its off a 6. 5L?



As for aftermarket guages... already done but would still like the stock dash to at least work. Any idea's on the tach???



RyanB

 

[FordCummins]

What motor did the truck come with orginially? The fittings for the Cummins water temp sender are just NPT fittings. Just use the necessary reducers or adapters to make it work with the GMC part from the motor that was originally in the truck.



As for the tach. Double check and make sure that you are getting a signal at the tach wire on the ALT. If you are, then make sure you are dealing with the right wire on the cluster. Other than that, I cant help you. I ran my tach off of the crank pulley, and through the PCM... . but we are dealing with 2 completely different trucks.

 

[RyanB]

Thanks for the info- The original engine for the wiring harness/dash was a 6. 5. I will get a 6. 5 temp sensor and use your advice. Can I pick up the tach signal with an ohm meter? or what do I use to check it.



Thanks... RyanB

 

[SOswalt]

Alright guys... here is a conversion question I have never seen before on here and hopefully someone can help me out!



I finally have my truck up and going but I am having clutch issues. For those that are not aware I swapped in a 12valve, 6speed and a Haisleys Comp Dual disk clutch.



My problem is that the hydrolic lines are bled and have no air at all... my clutch doesn't disengage untill the pedal is 1-2" from the floor (thats almost where the presure starts too!)



What I am thinking is that my GM master cylinder is way to small for the 97 Dodge Slave I have on the transmission. I have looked at the master on my brothers 97 Dodge and his is almost 2x's the diameter of what the GM unit is.



I am 100% sure this is my problem and have no idea what to do other than fabricate my firewall to exept the Dodge Master cylinder. If this is the direction to go in I will be getting one of the South Bend HD units with the quick disconect.



Also, I am having a few issues with wiring up my stock guages and my Alternator.



I am running a Dodge Alternator and had it built with a tach wire and also an external regulator. If anyone has used the Dodge ALT and wired a tach wire did it work right? for the life of me I can't get a signal... . maybe I have the wrong wire going to the dash (white wire... there are 2 lone white wires and can't figure out which one... anyway of testing them?)



Also, my Temp guage is acting strange. I ran the single GMC temp sensor wire to the Dodge sensor on Cummins (back of head... drivers side) and although it works, I think it rises twice as fast as it should and pegs out in no time when its still cool but some heat getting to it.



Anyone else ever experianced any of these please let me know... . RyanB



Here is a sneak peak of my engine (trying to get some wiring isues/clutch problems figured out and make my battery holder before I put my twins on!)

When I did my conversion I use all of my GM hyd parts,and use the dodge slave so yes it will all work.

Now the clutch my cause some of the problem with a stock slave?

 

[RyanB]

well thats the thing... Van Hasiley told me to put in a slave from a 1997 5-speed saying its the best for the big dual disk clutches... problem is that its oil capacity looks like double... if not more than the fluid capacity of my master. I think my only choice is to fab something to my firewall to make the dodge unit work!



Ryan

 

[DogDiesel]

Tach wire

Your truck is a 99, my GM conversion was a 93. My tach signal came from the alternator, it had a multiple pin rectangular plug, and the tach was the small wire on one side of the wire that plugged into the alternator. I isolated that wire and hooked to it.

I converted a Dodge alternator, using a computer chip wired inside and brought a tach signal wire of one of the stator windings. My tach works perfect.



I mounted my GM sender right front on head, because it will also sense excessive temps the radiator and fan cannot get rid of. The Dodge sender is still in the LR head unwired. My temps are between 150--180 with load, about 160 running empty.



As far as your clutch, match the hydraulic components, one way or the other. I used GM slave cylinder and GM clutch cylinder. Perfect function.



Unlike most on this board, I used a 12" GM flatface clutch and PP (LUK) and I have a very good holding clutch. I have probably towed more weight and more load with my conversion than any conversion mentioned on this board. I have over 90K on my conversion. It holds fine, I am mildly turned up in the 300-325 range only though, and I don't dump the clutch at pulls. Do more HP or pull, and more clutch is need.



Every conversion will incur different issues. Since we use different mounts, and position things different, we each will have unique problems with our particular fit. There will be many opinions on what and how to do it, and most will be right... until they see how you did it. Every conversion is different.

Trial and error. I went thru it too with my conversion, I wish you luck and success.

Wayne