GETRAG 5-SPEED

[MIDNIGHT RIDER]

I am the proud owner of a 1990 or 91 Cummins and Getrag 5-speed transmission.
Supposedly, it has little over 100,000 miles on the transmission.
Before I install the transmission in my truck, what is recommended that I should take care of while it is out??
At the worst, what is a reasonable $$ amount to expect to pay to have the transmission overhauled??
What would be the result of using Rotella 75/140 lubricant instead of the 5w30 I have read they call for??
Any other recommendations or pitfalls I should be aware of??

 

[steved]

I am the proud owner of a 1990 or 91 Cummins and Getrag 5-speed transmission.
Supposedly, it has little over 100,000 miles on the transmission.
Before I install the transmission in my truck, what is recommended that I should take care of while it is out??
At the worst, what is a reasonable $$ amount to expect to pay to have the transmission overhauled??
What would be the result of using Rotella 75/140 lubricant instead of the 5w30 I have read they call for??
Any other recommendations or pitfalls I should be aware of??

Running thicker oil might actually starve the tranny if the oil doesn't get slung around (depends on the design, of which I don't know)...I would go with a synthetic version of whatever they call for...

steved

 

[wannadiesel]

When I had mine redone the total bill came to $1500, but that included R&R and a SB Con-O clutch.

Do not run thick oil! The Getrag is assembled with preload on the bearings, not clearance. You need thin oil for good lubrication. If this is a working truck, run a good synthetic 5W-30 like Mobil 1, if it's a play truck run Redline MTL for quicker shifting.

Make sure you overfill it. I run 5 qts in mine.

 

[MIDNIGHT RIDER]

Since this post, I took it to a Getrag expert and had a bearing-synchronizer-seal kit and also replaced a bad fork and new speedometer gear.

Total bill was $570.

As I pull heavy stock trailers I guess I will go with 5 qts. of Synthetic Mobil 1.

What are thoughts on Royal Purple??

 

[Diesel_Junkie]

I would suggest putting an NV4500 in its place. You can probably get the whole thing for about $1500 or so.

All you need custom is the advance adapters bell housing, and a simple custom tranny mount adapter that they make also.
I did the swap on mine.

 

[MIDNIGHT RIDER]

With the NV4500 swap, is the same clutch-disc and pilot bushing used as is on the Getrag??

 

[Diesel_Junkie]

Yes, same disk and pilot, almost, while you are in there you probably want to change both anyways.,

The only differance in interface it that the stock first gen clutch disk has a longer spline interface on it, and reaches a little deeper towards the transmission, This would interfere with the neck of the input shaft housing on the Nv4500.

There are a couple options, take the input shaft housing off(4 bolts) and cut about a 1/2" off it.(no bid deal). Or use a clutch disk from a newer truck.

Look into the NV4500 kits, Advance Adapters sells you the whole kit with instructions, so you dont have to sweat details like this. The biggest pain is cutting a new whole in the floorboard, and covering the old one, cause the shifters come out in much different spots. This shouldnt take more than an hour or 2. I bought a shift boot for a 2nd gen to make mine pretty.

As an FYI, the clutch assemblies used in 2nd gen dodge cummins are cheap, and dont hold enough torqe for the motor to be turned up much at all. The first Gens came with a really cool clutch, with pleany of holding torque. I believe it is a SACHS brand. Super nice and really heavy. HD clutches for this thing are really expensive, like $500 or so. I would recommend taking your first gen origional clutch to a clutch rebuilder. I have heard this is cheap, and a good approach.

Dont forget to resurface the flywheel. That is only like $15.

I really dont like the getrags, I snapped 3rd gear in mine towing up a hill before i ever turned the motor up. They are just complete junk.

 

[MIDNIGHT RIDER]

I have the original SACHS >German I think< clutch and it impresses me much more than the later model ones I have seen.

Some have tried to put off a LUKS or somesuch on me; but, I said no thanks, I will stay with the SACHS.