Slipping in 2nd and 3rd.

[Bako_Dmax]

Can anything besides bad clutchs cause a slip only in 2nd and 3rd???

I put new clutchs about 2000 miles ago then the past couple weeks my trans has started to slip in 2nd and 3rd under moderate to heavy acceleration.

So I pulled the trans apart thinking to find bad clutchs. That wasnt the case I replaced them anyhow and still the same thing slips only in 2nd and 3rd. 1st 4th 5th and 6th hold full power no problem.

I have basically a suncoast III installed.

 

[Mike L.]

How did the C1 look? Did you air check the C1? How about C3 and C4 for clutch clearance? No codes? Sticky valves can cause a slip. Draggy trim valves or gain valves can cause a problem.

 

[Bako_Dmax]

The C1s looked new. I replaced them anyhow. I didnt air check the c1. The c3 c4 clearances were in spec and the only time I get a code is when I give it moderate-full throttle in 2nd or 3rd and i get the incorrect gear ratio codes.

Edit 1st gear is funky also. I dont think the c1s are bein fully applied if thats possible. How do I air check and what should I look for?

 

[Bako_Dmax]

Pullin the trans back out tomorrow again and I used red locktight this time instead of blue:baby:.. What should I check/look for besides the clutchs? I really think it has something to do with the c1s not being applied fully.

 

[Mike L.]

Pullin the trans back out tomorrow again and I used red locktight this time instead of blue:baby:.. What should I check/look for besides the clutchs? I really think it has something to do with the c1s not being applied fully.

Pull the piston out and check the seals on it.

 

[Bako_Dmax]

Mike would checking the pressures tell me anything?

 

[Mike L.]

Mike would checking the pressures tell me anything?

Yes. It will tell you if you have a pressure loss. You need to know what the pressures are supposed to be before it can help you. You will need a special adapter for your gauge.

 

[Bako_Dmax]

P/N 130-240 psi
Reverse 115-200 psi
forward tcc off 115-200psi
Forward tcc on 115-200 psi

Is this accurate since I have shimmed valve to raise pressure.

What adapter?

 

[Mike L.]

P/N 130-240 psi
Reverse 115-200 psi
forward tcc off 115-200psi
Forward tcc on 115-200 psi

Is this accurate since I have shimmed valve to raise pressure.

What adapter?

You need an adapter to install gauge fitting at base of bell housing. Your gauge fitting will be 1/8 pipe and your bell housing hole is 7/16 I believe.

 

[Bako_Dmax]

Pulled the trans did the air check. The c1s were not being engaged fully so I pulled the piston and this is what I found.

Can I get just the two seals for the c1 piston?

 

[JoshH]

It's been a while, but I think I bought just the seals once.

 

[Mike L.]

Pulled the trans did the air check. The c1s were not being engaged fully so I pulled the piston and this is what I found.

Can I get just the two seals for the c1 piston?

You should be able to get them from Allison. Glad you found the problem.

 

[Bako_Dmax]

It was big relief when I pulled that out and found it!

 

[Bako_Dmax]

You wouldnt happen to have part #'s for the inside and outer seals on the c1 piston?

My local alli dealer takes forever to find them if I dont have them.