Th400?

[rsh4364]

Is there an easy way to tell if you have a diesel TH400 or a gasser TH400?My new to me 86 1009 shifts a bit high even with vacuum valve regulator turned all the way towards firewall.

 

[Al Harvey]

Not 100% sure, but I think all the Diesels have the Heavy Duty case. On the top of the bell housing it will have HD stamped in it. Have you replaced the regulator and have your replaced all the vacuum lines. Also make sure the vacuum pump is actually working.

 

[welpro222]

I believe they are the same, the torque converter (stall speed) is the only difference that I know of.

 

[Gripy]

What vacuum pressures are you getting? Should be at least 20 psi before the regulator and 8 psi after (I put mine to ~10-12 for smoother shifting)

 

[rsh4364]

Tested vac. pump its good.replaced modulator it was bad,shifts really smoothed out.But still shifted kinda high in rpms.Adjusted vac.reg.valve on IP all the way towards firewall still shifts a bit high in rpm range,thats why I was Wondering if its a gasser TH400.Do I need a governor swap.

 

[Recovry4x4]

Governer is different as well.

 

[cpf240]

Have all the vacuum lines been replaced? A leak anywhere in the line can cause it to shift late. Also check the metal portion of the vacuum line(s), as it has been known to rub in places and get a hole in it.

As also mentioned, the weights / springs in the governor may be different than for a gas application.

 

[rsh4364]

Thanks everyone,vac.lines are good and have good readings everywhere,trans looks new,was just wondering if there was a quick visual check to determine whether gas or diesel.How much should I expect to pay for a gov. swap?My 85 1009 has a deep pan and no drain plug.The current 86 Im working on also has a deep pan but it has a factory drain plug.When did they start putting drain plugs on the th400 HD?

 

[Al Harvey]

My 86 doesn't have a drain plug. The HD should be on the passenger side of the bellhousing and is in fairly large letters if you want to feel for it. You should be able to see it in this picture. Depending on which modulator you have, you can make adjustments on it directly. If it's adjustable it will have a tiny screw in it where the hose attaches.

 

[cucvrus]

Not all the CUCV TH400 cases had the HD embossed in the case. I removed my transmission from my M1009 and it did not have the HD. It did have the last 8 of the vin on the right side forward ear. So it did come from the factory in that M1009. The PDI sheet was also under the passengers seat in an envelope when I bought the truck with the engine # Transmission # and axle #'s. I never saw it till I removed the bucket seats. It had lots of valuable information. So I am saying it was hit or miss on the HD embossed transmission cases. Some had them some did not. Side by side they look the same. Replacement cases had a heavier tail section and some of them had the HD and some not. No rhyme or reason to it.

 

[rustystud]

You will normally have the HD case if you have the case support struts. These struts go from the engine mounts to the torque convertor cover (heavy aluminium cover). If you didn't have the struts you didn't need the heavy case. As to why all the trucks didn't come with struts, who knows ?