Author Topic: Compact Gforce G101A Transmission  (Read 11276 times)

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Offline awelker

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Compact Gforce G101A Transmission
« on: August 03, 2015, 10:53:40 PM »
Thought I would share part of my upgrades from this year incase anyone is looking for a similar solution.

I originally built my bellytank with a early Ford side shift transmission and only used 2nd and 3rd gears. This was two much of an rpm drop and was nervous about breaking it as I plan for more power. My trans was direct coupled to the quickchange and very space limited. After a lot of research and a trip to Gforce (luckily they are only an hour from me) I came up with this solution.

The g101a 4 speed uses the same 32 spline for the output shaft and the reverse gear. So simply the tailshaft can be cut off and any output coupler can be used. A new rear seal plate is made to cover up what the tail housing normally did. To couple to the rear I found the Mark Williams gear coupler to be the most compact that can assembled blind.

End result is trans case plus mid & rear plate at 11 1/8" long plus about 2" for the gear coupler.  To save space on the front end used an original Flathead big truck hogs head which housed my throw out bearing the same as before and had the input shaft machined to match the early ford trans.




Offline SPARKY

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Re: Compact Gforce G101A Transmission
« Reply #1 on: August 03, 2015, 11:09:54 PM »
look at it---look at it--- pretty, pretty,---- pretty slick I'd say  :-D

« Last Edit: August 04, 2015, 01:17:44 AM by SPARKY »
Miss LIBERTY,  changing T.K.I.  to noise, dust, rust, BLUE HATS & hopefully not scrap!!

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Offline wheelrdealer

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Re: Compact Gforce G101A Transmission
« Reply #2 on: August 03, 2015, 11:10:19 PM »
Nice.

BR
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Offline 4-barrel Mike

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Re: Compact Gforce G101A Transmission
« Reply #3 on: August 04, 2015, 12:10:16 AM »
Cool stuff, including the KRW engine stand.   :cheers:

Mike
Mike Kelly - PROUD owner of the V4F that powered the #1931 VGC to a 82.803 mph record in 2008!

Offline tauruck

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Re: Compact Gforce G101A Transmission
« Reply #4 on: August 04, 2015, 01:11:17 AM »
This is one NEAT build.
Shocking attention to detail.  :cheers: :cheers: :cheers:

Offline gray63

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Re: Compact Gforce G101A Transmission
« Reply #5 on: August 04, 2015, 08:26:34 AM »
Great job Andy.
Now if we can get some solid salt to run on.

Dave
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BGMS

Offline Rex Schimmer

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Re: Compact Gforce G101A Transmission
« Reply #6 on: August 04, 2015, 03:55:35 PM »
That is some nice engineering and fabrication. Also like your headers and the fabricated blast shield. Very nicely done!!!

Rex
Rex

Not much matters and the rest doesn't matter at all.

Offline mike f

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Re: Compact Gforce G101A Transmission
« Reply #7 on: August 04, 2015, 08:03:26 PM »
Hi to all:  for general information short style transmissions have been done for years.  You can get a shorty Jerico  from any dealer, Roltek has a shorty style, which is a 3/4  T101A.  No need to reinvent the wheel when the engineering and work is already done.  Mike

Offline awelker

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Re: Compact Gforce G101A Transmission
« Reply #8 on: August 04, 2015, 11:06:35 PM »
Thanks for the comments. Always intended to do a build diary but never had the time. Maybe now that the salt and all my money have disappeared I can do a build recap.

As for other shorty transmission, yep I know they are out there. The jerico main case is at least an inch longer than what I ended up with since reverse is in the main case.  Roltek, never heard of them but guessing they didn't have an off the shelf solution for '48 flathead to Halibrand quickchange.  But maybe they did.

Offline Sumner

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Re: Compact Gforce G101A Transmission
« Reply #9 on: August 05, 2015, 12:55:41 PM »


Very nice work!!  :cheers: :cheers:

So did you make the plate that mounts where the tailshaft was or is that something someone is selling?  Any pictures you have of that would be appreciated when you find time.  



Also interested in how you engineered the shift linkage.  Anymore pictures on that?  And finally what rear gear ratio are you starting with and tire size?

Sumner
« Last Edit: August 05, 2015, 01:00:44 PM by Sumner »

Offline awelker

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Re: Compact Gforce G101A Transmission
« Reply #10 on: August 05, 2015, 03:25:45 PM »
Yes I made the plate that takes place of the tail shaft housing.  I drew it in Solidworks and we CNC milled it where I work, easily could make another if you are interested.  The dark gray ring on the back holds a seal and also locates the transmission alignment to the rear axle.  If you were doing a short driveshaft this could just be a seal holder.  I will look for more pictures but this was at the height of scramble time and they are limited.

For shifting I used two cables with 3/8" threaded ends (which are quite substantial).  In the cockpit I got a box of shifter parts from Gforce for their 1000 series rail shifter.  Normally this has 3 shifter rails, so i cut it apart and narrowed it to only have 2 (if you had the space this would not be necessary).  The shifter assembly hangs upside down between my knees and worked out to a standard 4 speed H pattern.  Will look for some pics of this as well. 

Andy

Offline awelker

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Re: Compact Gforce G101A Transmission
« Reply #11 on: August 05, 2015, 03:33:27 PM »
Cables not connected yet at shifter end in this pic. Will take another pic tonight.


Rear axle boss that locates to trans.

Offline Sumner

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Re: Compact Gforce G101A Transmission
« Reply #12 on: August 05, 2015, 09:11:37 PM »
....So simply the tailshaft can be cut off and any output coupler can be used. ...

Thanks for the added pictures.  The quality of all the work is outstanding.  It has been 2 years since we had one of these apart so my memory isn't good.  Refresh me please. 

The mainshaft goes all the way through and out the back of the tailshaft in the stock configuration??  The reverse gear has 32 tooth splines and is on the mainshaft's 32 tooth inner splines?  You cut the mainshaft at the back end of the splines that reverse normally is on and the splines will now stick out the backside of the new back plate that you made and the coupler or u-joint yoke can slide on what is now the output shaft??

Thanks,

Sum

Offline awelker

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Re: Compact Gforce G101A Transmission
« Reply #13 on: August 06, 2015, 09:19:55 AM »
Sumner,

There is separate input and output (or tail) shaft.  The transmission case is made up of main case, mid plate, and the tail housing.  The main case and mid plate can be used as is, I machined some extra material off just for clearance.

Yes the normal tail shaft has 32 spline output, which is exactly the same as the reverse gear splines which start just behind the bearing in the mid plate.  The tail shaft was cut off and threaded in the end for a bolt to hold on the coupler, otherwise yes these splines now become your output shaft.

« Last Edit: August 06, 2015, 09:23:24 AM by awelker »

Offline Sumner

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Re: Compact Gforce G101A Transmission
« Reply #14 on: August 06, 2015, 10:28:33 AM »
Thanks for that and I think I had it all pictured right.  I'm going to lengthen the lakester switching to a car motor and the 101 and looking again yesterday at the 101 feel I will have the car length to work with the transmission as is but who knows about the future when it might be nice to cut the driveline length back for packaging.  

I already have had a short driveshaft made up and would want to stay with that so would need a new back plate like you made with just a seal in it.  This is something that could be made say this next winter or later.  If it is something you might be able to do PM me a price for one and I'll get back to you and thanks again.

On a different note the following ....

.....There is separate input and output (or tail) shaft......

..... reminded me of something you might or might not know about.  There is a needle bearing up front where the output shaft rides inside of the back of the input shaft.  G-Force told me recently that if we flat tow the cars for some distance on the salt and that bearing isn't getting lubed that it could fail.  They went through a couple possible ways to do that.  

I'm guessing that if the input shaft is turning and the drive gears are turning they are picking up oil and slinging it up into the area where the needle bearing is and if you are towing then the output shaft is turning in the bearing but maybe no oil is getting up to that area.  One thing that I think helps in our case is that with the 2.47 rear gears and towing the car under 40 mph the output shaft isn't turning that fast.  If we get to go this year we might try and tow a little slower.

We have towed the car a lot on the salt and it has never been a problem, at least we think the bearing hasn't been hurt but we will probably address this over the winter.  Not sure how you are going to move your lakester on the salt but you might want to talk to them about it.  I'll do something about it for the 101 that I have for the lakester.  The 101 Hooley bought for the Stude has provisions for an external pump for lube and we might be able to use that with his.  We won't know until we can get to the transmission and take some pictures of it and send them to G-Force as they had different versions of the ones setup for the external pump and I guess some lube the needle bearing area and some don't.

Sumner
« Last Edit: August 06, 2015, 10:30:37 AM by Sumner »