Gm400 gearbox

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Jul 25, 2018 | 02:10 PM

#21

Steve M

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From: Wiltshire, UK

Mine has a slightly noisy first gear if I stick it in first and take off; if it kicks down into first it isn't noisy?
What's all that about then?

Jul 25, 2018 | 03:40 PM

#22

ronbros

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From: Austin tx and Daytona FL.

Quote:

Originally Posted by motorcarman

Too bad you are not local to me in Texas USA. I have a NEW-IN-BOX THM400 (3L80) that I would sell for the price of a rebuilt unit.
It is still in the wood ship crate with steel bands. I think it was made in the early 1990s for all 5.3 XJ-S from 1989 onward.
Part number EBC3654N. I would guess shipping to Europe would end up costing more than you could get a reman locally.

I have a 1988 C2500 Chevy Pick-Up that has a THM400 and thought about stripping the Jaguar internals and putting them in the Chevy case but the truck is working fine so no point I guess. It would be a waste of a good Jaguar gearbox to fix a common Chevy truck.

bob

bob most of the trucks Chevy/GMC had heavy duty parts in them anyway!

Jul 25, 2018 | 07:00 PM

#23

Jagboi64

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From: Calgary, Canada

Quote:

Originally Posted by ronbros

my suburban 4L80 has no noise from any gear

The 4L80 starts in second gear unless in sport mode, so you avoid the typical first gear whine most of the time. Sort of sounds like the moss box first gear whine in 1950's and 60's Jaguars until they went to the all syncro gearbox.

Jul 28, 2018 | 11:45 AM

#24

ronbros

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From: Austin tx and Daytona FL.

Quote:

Originally Posted by Jagboi64

,, the 4L80E in trucks and HD equipment starts in 1st when in drive position, they dont have sport mode, that position is for passenger cars!

Jul 28, 2018 | 11:55 AM

#25

ronbros

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From: Austin tx and Daytona FL.

quick history about GM auto boxes, when 1st engineered it was a military problem , the 1st generation TANKS were standard shift ,NO syncromesh so young men trying to drive them tore up gears and often left stranded , also burned clutches out by the dozens, revin to get moving in top gears!

so Allison gear company GM helped design some Hydraulic shift trans, the OLD 4speed cast iron box, also put into Oldsmobile cars 1939, i owned some!

well as engines got bigger with more torque, GM designed the incredeble 3speed 400 for both light tanks and road cars.

WIKI got info about them.

ron

Jul 28, 2018 | 04:50 PM

#26

motorcarman

Joined: Dec 2009

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From: Wise County,TX

I work on a bunch of Rolls Royce and Bentleys that use the HYDRAMATIC gearboxes. I think they were first used in the Silver Dawn and Bentley 'R'.
Then the Silver Clouds (Bentley 'S') used them. The GM 400 (3L80) was introduced in the Silver Shadow (Bentley 'T').

Different clutches? and valving to shift SMOOOOOOTH but otherwise the same.

Trans rebuild shops always quoted a price for the THM 400 until we brought the Jaguar or Rolls Royce trans and they looked at the bell housing and asked "what is that out of?"
We told them and then they wanted to 'up-the-price'.

bob

Jul 28, 2018 | 07:12 PM

#27

Daim

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From: Bremen, Germany

Bob, you notice that everywhere. I was looking for a new transmission selector shaft. There are 3 or 4 different lengths. The Jaguar Version is the same as some Chevy or AMC shaft. Can't remember the length. Anyhow, looking through suppliers:

SAME manufacturer parts number on the SAME size revealed 3 prices:

Chevy: cheap
AMC: 2x Chevy price
Jaguar: 3-4x the Chevy price

All for the same shaft... Just because Jaguar seems to cause the $_$ face...