shift kit pro's and cons

J

joe williams

New member
Oct 31, 2016
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the GMC I'm looking at buying has a shift kit installed , is this a good thing or bad ?
have read a few previous posts stating that Manny doesn't recommend them. but why?
and how complicated is it to remove and can it be done fairly easily ( by me )without doing harm to tranny?
thanks to all for info
Joe
--
jwilly
 
> the GMC I'm looking at buying has a shift kit installed , is this a good thing or bad ?
> have read a few previous posts stating that Manny doesn't recommend them. but why?
> and how complicated is it to remove and can it be done fairly easily ( by me )without doing harm to tranny?
> thanks to all for info
> Joe

Joe,

If Manny thought it was a good idea, he would do it. As to is it worth removing or killing the deal, you will have to ask Manny. He will answer both
and you can take his answers to the bank.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Still Loving OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
> ...Manny doesn't recommend them. but why?...

Don't know. Don't care. If Manny takes them out and throws them away, that is all I need to know. It doesn't belong in the transmission.
--
73 23' Sequoia 4 Sale
73 23' CanyonLands Parts Unit 4 Sale
Upper Alabama
"Every day I become more convinced that I am the only person left on the planet that recognizes nonsense for what it is."
 
Don't do it or you could damage your engine. It cost me 2 engines. First one over reved in low gear when I accidentally pulled it into low thinking
it was super. You can't pull the trans into low if the rpm is too high with the stock trans but with a shift kit it will go into low. 2nd one damaged
the thrust bearing from extremely hard upshufts. After this I had Manny remove the kit and redo the trans. If you are a flatlander you may never have
a problem but living in a mountain state is hard on drive trains cause you are always working it hard climbing steep grades while towing.
--
Roy Keen
Minden,NV
76 X Glenbrook
 
the guy who built the trans for my vette said that shift kits are designed to shift hard so the driver thinks it is better, but it's not a good shift and is hard on the transmission.

To do it right he changed some internal programming in the trans.

The vettes trans will go into whatever gear you tell it to, It also does shift very hard on WOT, but putting around it shifts nice.

I would not put a shift kit in anything, much less a motorhome.

I would let Manny update it however.

________________________________
From: Gmclist on behalf of roy keen
Sent: Thursday, May 18, 2017 11:07:14 AM
To: gmclist
Subject: Re: [GMCnet] shift kit pro's and cons

Don't do it or you could damage your engine. It cost me 2 engines. First one over reved in low gear when I accidentally pulled it into low thinking
it was super. You can't pull the trans into low if the rpm is too high with the stock trans but with a shift kit it will go into low. 2nd one damaged
the thrust bearing from extremely hard upshufts. After this I had Manny remove the kit and redo the trans. If you are a flatlander you may never have
a problem but living in a mountain state is hard on drive trains cause you are always working it hard climbing steep grades while towing.
--
Roy Keen
Minden,NV
76 X Glenbrook

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Agreed. If Manny says no shift kit then no shift kit it is.

Sully
77 eleganza 2
Seattle

> the guy who built the trans for my vette said that shift kits are designed
> to shift hard so the driver thinks it is better, but it's not a good shift
> and is hard on the transmission.
>
> To do it right he changed some internal programming in the trans.
>
> The vettes trans will go into whatever gear you tell it to, It also does
> shift very hard on WOT, but putting around it shifts nice.
>
>
> I would not put a shift kit in anything, much less a motorhome.
>
> I would let Manny update it however.
>
> ________________________________
> From: Gmclist on behalf of roy keen <
> roynpaula>
> Sent: Thursday, May 18, 2017 11:07:14 AM
> To: gmclist
> Subject: Re: [GMCnet] shift kit pro's and cons
>
> Don't do it or you could damage your engine. It cost me 2 engines. First
> one over reved in low gear when I accidentally pulled it into low thinking
> it was super. You can't pull the trans into low if the rpm is too high
> with the stock trans but with a shift kit it will go into low. 2nd one
> damaged
> the thrust bearing from extremely hard upshufts. After this I had Manny
> remove the kit and redo the trans. If you are a flatlander you may never
> have
> a problem but living in a mountain state is hard on drive trains cause you
> are always working it hard climbing steep grades while towing.
> --
> Roy Keen
> Minden,NV
> 76 X Glenbrook
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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The idea behind Transgo and other kits was to speed up the shift event and have less overlap. This in theory minimized the time the clutch packs were
slipping in a sacrificial manner. However this increases stresses elsewhere as the stored RPM energy had to be rapidly disipated. The guys at
Hydramatic were the best in the business at programing-- balancing comfort, drivability, durability and performance. That is 4 vectors kind of like
trying to have the old "balancing eggs on eggs" task work out. They were designed to shift seamlessly imperceptible under light throttle and firm as
loads increased. If you think about it in an 11k vehicle the loads are always high as if towing. Also going to harder shifts is a bad idea with FWD
where uneven traction surfaces can jerk you into another lane with hard shifts.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
Joe,
Don't be discouraged by the shift kit. Our '78 Eleganza, with the 403, had a Danny Dunn transmission installed in 2003, and it has a shift kit. I do
not intend to start an argument, but some think the shift kit is OK. I posted some information about it here:

http://www.gmcmhphotos.com/photos/g7043-danny-dunn-transmission-information.html

Our GMC has been actively used by its previous owners, with no other transmission repairs recorded by them. We have only owned it since August of
2016, but use it frequently. We just drove it 700 miles round trip to the Florida Keys for the GMC Sunshine Statesmen Rally with no trouble at all.
(By the way, I highly recommend joining your local GMC club; the information and help you'll receive from them is priceless!) I did put in a rebuilt
governor assembly, and a new vacuum line on the modulator; but other than that, the transmission works great!! It does have a firm shift, and I drive
it conservatively, but the transmission works just fine. I live in Florida, and I haven't driven it in the Mountains since we drove it home from New
York, where we bought it. I get a consistent 10 mpg.

I say go for it! Buy it. Use it. Enjoy it. If the transmission fails, fix it. I know a guy. *wink*

If my tranny ever fails, I'll probably call Manny for a 'new' one.
Russell
--
Russell Keith

1978 Eleganza II

Dunedin, Florida
 
Yes "Shift Kit" is a blanket statement. Some are mild, some are extreme, some are finicky. Most manufacturers had them in different flavors so you
can't paint with a wide brush and expect to be accurate.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
The big problem with user installed shift kits is they cant address int he internal changes needed ( as I remember from my transmission guy ) they can only change the valve body programming.

Stock transmission use clutch overlap to smooth out the shifting, but that means two gears are applied at the same time for a while.

A performance transmission does not do that. It's easier on the transmission, but a bit harder on the rest of the driveline, esp on high performance cars pushing the limits of the components.

________________________________
From: Gmclist on behalf of John R.Lebetski
Sent: Friday, May 19, 2017 7:50:59 AM
To: gmclist
Subject: Re: [GMCnet] shift kit pro's and cons

The idea behind Transgo and other kits was to speed up the shift event and have less overlap. This in theory minimized the time the clutch packs were
slipping in a sacrificial manner. However this increases stresses elsewhere as the stored RPM energy had to be rapidly disipated. The guys at
Hydramatic were the best in the business at programing-- balancing comfort, drivability, durability and performance. That is 4 vectors kind of like
trying to have the old "balancing eggs on eggs" task work out. They were designed to shift seamlessly imperceptible under light throttle and firm as
loads increased. If you think about it in an 11k vehicle the loads are always high as if towing. Also going to harder shifts is a bad idea with FWD
where uneven traction surfaces can jerk you into another lane with hard shifts.
--
John Lebetski
Woodstock, IL
77 Eleganza II

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I've rebuilt many T400s, and a few T425s. As others have said. A very durable transmission. As an example. I just changed the trans in Barb's 73 GMC. That trans had never had any repairs made to it by the service records. And the extreme amount of grim built up on it. 220,000 mile, and pulling a toad. The key was timely fluid, and filter changes. Thus getting the junk out at each change. ( As a note. It never had synthetic put in it. ) So how could synthetics do better? GM's shift programming is excellent for our application. I've put shift kits in some of my trans at rebuild time. But to me. Our GMC's aren't the place to install one. Want mileage out of your T425. Let up a little at it's shift times. Change fluid, and filter at every 25,000 miles. Synthetic or not. I'm always pulling something. Much of the time my 403 is pulling up to 21,000 lbs GVW. And I have the 3:70 FD. Bob Dunahugh
 
thanks for info, I'm going to give the owner another call and find out more about it,
he told me that Ken Frey did the work so I think it's installed correctly ,I may have to give Ken a call to find out more.
Joe
--
jwilly
 
Just curious..is Danny Dunn still doing transmissions??
Tks

Mike in NS

> thanks for info, I'm going to give the owner another call and find out
> more about it,
> he told me that Ken Frey did the work so I think it's installed correctly
> ,I may have to give Ken a call to find out more.
> Joe
> --
> jwilly
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS

Life is too short to hold a grudge; slash some tires and call it even !
 
No not for a long time!

JR

>
> Just curious..is Danny Dunn still doing transmissions??
> Tks
>
> Mike in NS
>

>
>> thanks for info, I'm going to give the owner another call and find out
>> more about it,
>> he told me that Ken Frey did the work so I think it's installed correctly
>> ,I may have to give Ken a call to find out more.
>> Joe
>> --
>> jwilly
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
>
> --
> Michael Beaton
> 1977 Kingsley 26-11
> 1977 Eleganza II 26-3
> Antigonish, NS
>
> Life is too short to hold a grudge; slash some tires and call it even !
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Put in a number of 'shift kits' on SOBs years ago. These were Transgo brand as I recall, and were very mild- specificly for towing and RVs. THey only
slightly firmed the shifts and required very little modification.

But you will definitly have issues if you put a high performance or race kit in heavy vehicle. It will increase the shock load, and although the 425
is a strong trans you will probably find the weak link.

That being said, ultra smooth barely perceptable Cadilac shifts come at the cost of slippage, and in a heavy high load vehicle would cause wear. I
would imagine GM took settings into account for our applications

On a high powered light weight car, they do make a difference in durability.and performance. However, most trans guys I know do their own mods rather
than a kit per se. Ill wager Manny boosts the line pressure a bit or tweaks something in the valve body a little without making the shits harder.

--
76 Glenbrook
 
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