Jezza355

Hi everyone ,
new member here. Currently rebuilding my 94 4l60e for my holden commodore (aussie ).
trans was removed for a freshen up and some upgrades as the car it runs in is making 640hp at the motor compared to 500ish it had before .
I've been looking at forums and reading as much info as possible to help guide this build and give the trans a chance at living a long healthy life .
car is going to be mainly strip, max of 8000rpm
5500rpm converter
car weighs 3600lbs
looking at the internals after the teardown ,
I was thinking of machining out the splines of the input housing and substituting the seal for a roller bearing for the output shaft to fit inside and act as an extra support.
has anyone ever done this ?
thoughts ?
cheers
Jeremy

MaroonMonsterLS1

There is already a thrust bearing there between the drum and input sun gear.
The output shaft comes through the sun gear and sits in the pocket of the input drum/shaft and seals there. The input sun gear has two bushings that ride on the output and keep it centered just fine.

What is your goal or thought here? This trans doesn't have any huge glaring issues with runout or thrust...so I'm not sure what you're trying to correct.

Jezza355

Not really trying to correct anything , more so improving .
looking to see if anyone has ever done it and if any benefit.

bbond105

I don't know of anyone who has tried that or even why you would want to install a bearing there. If you do try it, I would use a stock drum first, just in case it doesn't work. How are you going to seal the output shaft to the input drum? The weak link in my 4L60E is the input sprag and overrun clutch hub.

MaroonMonsterLS1

Ok...if you're not trying to correct...then what do you think you're improving? What do you think the benefit will be? And do you mean bushing...because there is already a thrust bearing in that location.

I don't see what benefit you are looking for...maybe if we know what you're looking to benefit...we can recommend ways to get there.

Jezza355

it would obviously help with radial loading and support of the output shaft , this can only be a good thing. It wouldn't be helping for thrust .

MaroonMonsterLS1

And do you see serious problems with radial loading in this transmission? Do you see any signs of excessive runout from unsupported radial loading? Do you see massive bushing wear somewhere in the trans that warrants needing a fix? Do you see components interfering with each other and rubbing or showing signs of accelerated wear or chances of failure?

I guess what I'm asking is...do you see a need to improve something? or does it just sound like a fun idea?

Jezza355

http://4l79.com/?product=input-to-ou...al-support-kit

Has been done before , a different way than machining the input drum to fit a roller bearing .
I lprefer this method.
also has a clear description as to why its benneficial and not just a "fun" idea .

MaroonMonsterLS1

That's a part made by Mason. He makes some good stuff.

It's a cool concept, but far from necessary. I ask again...what are YOU trying to accomplish? Are you having issues with bushings getting wiped out? Are you spinning crazy rpm where you think something like this will be needed? Are you seeing multiple planet failures caused by something not running on center?

There are WAY more failures caused by leaks at that little seal that bleed off lube oil to the back half of the trans. I hope that your design has a very positive seal or you can say goodbye to all of the rear bushings...even if they are running perfectly true

I know that I personally have not seen enough issue to warrant anything like this. I know lots of guys that aren't either.
Everything from 250k mile trucks to 700hp camaros (yes with a 4l60e) don't run that part and they are just fine...the bushings live. The planets live. etc...so in my opinion, Clearly it's not a critical area that needs attention.

And, side note...if you already know of a part out there on the market that does exactly what you want...why bother trying to reinvent the wheel. Spend the $100 and get the part.

Jezza355

No I've had no issues with any of that , this trans lived for 9 years without most of the fancy stuff inside at a power level of around 500hp .
all that was In it was a hd2 kit , pump rev kit , b/w HE friction pack and a bw 29 element sprag.
that setup only ever saw around 6800rpm .

new engine has 640hp and will be revving to 8000rpm , maybe 8250.
I was thinking that supporting the shaft and helping keep a true centerline while turning the box to those rpms would only help that little bit more to keep things in check .

I had thought of the idea and was merely looking to see if others may have done it , known of it or could point me in the direction to a place that sells the setup.

Thankfully for me I received some great advice from a very well known trans builder in the USA on another forum , knowing exactly what I was talking about and he does this mod to all his high power 4l60/65e boxes and especially high revving applications as it helps with harmonics through the unit.

he even sent me pics and measurements and supplied the number of the bearing and the best way to install.

he also gave me the part number for the unit from 4l79.com to have a look at .

one thing you have to accept is there's many ways to skin a cat , just because you didn't know of this doesn't mean you get to question and say its not necessary , if it helps to keep my box alive and run smoother then I'll be giving it a go .

MaroonMonsterLS1

I never said I didn't know about it. The whole point of this forum is to have some intelligent conversation. I could have dropped a link in the first comment and been done there...but nobody would have learned anything. The whole point was to get some critical thinking and make sure you thought about the mod before you went and started machining things.

I also missed your comment about butthurt. Not a great way to get any help...maybe next time look into post history and find that I'm pretty active in the trans section of the forum and plenty willing to help. I guess I just don't always spoon feed and maybe that's what you wanted.

Fact of the matter is...its a mod that doesn't necessarily hurt anything and can maybe make the trans run more true to the center...but this isn't a trans that has any serious issues with that. Even at 7500+ rpm. So it's not something that is needed or strongly recommended by many builders.

If you want to wear the engineer hat and start spinning things in a lathe...you'll be much better suited trying to figure out how to cure the line rise issues at high rpm...curing internal circuit leaks...fixing the VB...and correcting the inherent weak points in the 3/4 clutch circuit. Lucky for you (just like with Mason's 4l79 part) most of the engineering in these areas has already been done and you can buy the parts you need. But for anything else...design it and sell it...maybe I'll buy it

Jezza355

anything thats revving over 7k is going to need attention to detail internally .
this ain't my first box .

I will say again , I was asking for people that have used the idea before or know of it. I now have good information on this modification, one that's so popular Mason at 4l79.com is out of stock .

sjsingle1

iTrader: (1)

I dont know much about that part......but his mod for the 3/4 clutch pack looks very interesting

Jezza355

hes got some really trick stuff , glad I was given the link to his site .

98CayenneT/A

True story.
Very helpful.

Im a big fan of MaroonMonsterLS1, definitely puts in time here that's appreciated.

PBA

This is very similar to the TH350 when it was using a bronze bushing to keep the output shaft centered. It didn't keep it centered and was a disaster. GM finally went to a plastic seal to keep the lube circuit functioning, and it did very well. So keeping it centered was not necessary. The planetaries have a tendency to center themselves. Ford C4's were a perfect example. Unless you are wearing bushings out at a fast rate, then you would have to find out what is going on.

Jezza355

thanks for the reply , what was the disaster with the th350 and the bushing? Was was the end result .

MaroonMonsterLS1

The th350 had a small OD "tip" protruding from the input shaft and a counterbore in the output shaft that the "tip" fit into. There was a bronze (or later plastic) bushing between the two. It was only that bushings clearance tolerance that sealed the lube oil flowing through the input to the output. It kept the shafts running on center together...but any vibration, or runout would eventually wear out the bearing and then all that lube oil would leak past it...causing a chain reaction that wiped out the rest of the bushings.

This is why th350's are notorious for needing every bushing replaced during an overhaul.

The 700r4 was an example of GM learning from their mistakes in this area...which is why they went with the rubber seal. It could handle slight runout and vibration issues and still seal lube oil. They determined (and I agree with Gm on this one) that the there would be little to no issue with not having those shafts centered on each other. The track record of the trans proves this to be true...they don't have serious bushing wear...you don't have drums hitting each other and wearing out...you don't see any real problems that would require a design change.

Jezza355

thanks for that reply , think we started off on the wrong foot.
cheers again

PBA

In between the bronze bushing (first design) in the output shaft of the TH350. There was a second design before the plastic insert. The input shaft had a ring groove in it for a Teflon ring that sealed against the bore in the output shaft. I have seen these, however they were very rare. And the third design ended up with the plastic insert that worked out well. In the 700R4 the first design used a plastic seal that sat in the input drum and the seal hugged the output shaft. Worked well until the plastic seal started to wear. This started a decline in oil reaching the rear area of the transmission, mainly the rear planetary. The early 700R4's were notorious for burning up the rear planetary. TransGo had you grind the land on the pressure regulator valve which controls lube to the rear and this modification greatly increased the flow to the back half of the transmission, even when the seal was shot, and this greatly helped planetary life till the final solution, was GM's introduction of the Viton rubber seal which was introduced in late 1991. The odd thing is that when you buy the 700R4 paper and rubber kit or overhaul kit from any parts supplier, you will never get the Viton seal with it, just the early plastic seal. So you have had to buy the Viton seal separately. I have put them in all 700R4's that I build or rebuild kits since I found out about this Viton seal back in the early 1990's. The Viton seals greatly improved the durability of these units.