Any helpfut hints for those of us stuck with the dreaded 4L60 suburban tranny?

[Larry]

That actually sounds like the best advice. I have really been interested in this avenue. How much total weight (sub, and any towing weight can it handle, and how about when trying to start from from going uphill, can the clutch handle it? does it mate as is to the engine, mounts, and transfer case?

What? Really? Due to your question it sounds like you may not have much manual transmission experience? Well, absolutely a NV4500 manual trans and 12” clutch can handle the GCWR of any Suburban but I guess it all depends on the driver too….especially with respect to the clutch performance. In fact, back in the day when these old Burbs and trucks were roaming the earth manual transmissions were the towing transmission of choice as 700R4’s and 4L60’s were known to be grenades although TH400’s weren’t bad (At least that is the way it was in this part of the country). It wasn’t until later years (say, mid-90’s) when automatics started becoming more durable where they took the towing transmission of choice by many.

To answer the second round of questions, yes…a NV4500 would bolt up to the engine with the proper bellhousing…but no…your existing transfercase will not fit on a NV4500 as you have a 27 spline transfercase now whereas you would need a 32 spline from behind a TH400 or SM465 4 speed manual. The biggest difference between my Burb and yours is the fact mine started off life as a manual trans, albeit only a 4 speed, so the NV4500 5 speed swap was a bit easier since the pedals were already there and the tcase had the correct spline count. Regardless of which trans (700R4/4L60 or SM465) the trans crossmember will remain in the same location when swapping to a NV4500 5 speed. See my Polar Bear thread for more details.

 

[Rockhounder]

What? Really? Due to your question it sounds like you may not have much manual transmission experience? Well, absolutely a NV4500 manual trans and 12” clutch can handle the GCWR of any Suburban but I guess it all depends on the driver too….especially with respect to the clutch performance. In fact, back in the day when these old Burbs and trucks were roaming the earth manual transmissions were the towing transmission of choice as 700R4's and 4L60's were known to be grenades although TH400's weren't bad (At least that is the way it was in this part of the country). It wasn't until later years (say, mid-90's) when automatics started becoming more durable where they took the towing transmission of choice by many.

To answer the second round of questions, yes…a NV4500 would bolt up to the engine with the proper bellhousing…but no…your existing transfercase will not fit on a NV4500 as you have a 27 spline transfercase now whereas you would need a 32 spline from behind a TH400 or SM465 4 speed manual. The biggest difference between my Burb and yours is the fact mine started off life as a manual trans, albeit only a 4 speed, so the NV4500 5 speed swap was a bit easier since the pedals were already there and the tcase had the correct spline count. Regardless of which trans (700R4/4L60 or SM465) the trans crossmember will remain in the same location when swapping to a NV4500 5 speed. See my Polar Bear thread for more details.

No problem with the shifting, I have Lotus Esprits which are manual, and learned to drive on a 76 toyota Celica gt, manual....biggest thing I drove manual was a WW2 vintage Coleman Road Grader.... that was one of the reasons I was asking about the clutch performance, to be more specific, when under load, does it grab with a bang, jitter, or slowly slide-engage when trying to haul a heavy tow load? I'm imagining that it is perhaps a 13-15 inch disc/single disc with typical spline finger spring?

As to the diffferent T-case, and bell housing, thanks for the info. I would also have to install a clutch pedal, perhaps an aftermarket hydraulic if original is unobtanium. Will also of course have to do bodyfab to make the shifter work as well. Just for the bell housing, tranny, clutch disc, and new T-case, how much do you think that might run, and are there any outlets to find these for sale?

 

[hidesertwheelin]

No problem with the shifting, I have Lotus Esprits which are manual, and learned to drive on a 76 toyota Celica gt, manual....biggest thing I drove manual was a WW2 vintage Coleman Road Grader.... that was one of the reasons I was asking about the clutch performance, to be more specific, when under load, does it grab with a bang, jitter, or slowly slide-engage when trying to haul a heavy tow load? I'm imagining that it is perhaps a 13-15 inch disc/single disc with typical spline finger spring?

As to the diffferent T-case, and bell housing, thanks for the info. I would also have to install a clutch pedal, perhaps an aftermarket hydraulic if original is unobtanium. Will also of course have to do bodyfab to make the shifter work as well. Just for the bell housing, tranny, clutch disc, and new T-case, how much do you think that might run, and are there any outlets to find these for sale?

Here is a guy selling a complete set up for $2k :Wow1: And you would still have to get the proper tail shaft and t-case adapter installed (at least, maybe even more. Larry would know).

http://orangecounty.craigslist.org/pts/4836314393.html

 

[Larry]

No problem with the shifting, I have Lotus Esprits which are manual, and learned to drive on a 76 toyota Celica gt, manual....biggest thing I drove manual was a WW2 vintage Coleman Road Grader.... that was one of the reasons I was asking about the clutch performance, to be more specific, when under load, does it grab with a bang, jitter, or slowly slide-engage when trying to haul a heavy tow load? I'm imagining that it is perhaps a 13-15 inch disc/single disc with typical spline finger spring?

As to the diffferent T-case, and bell housing, thanks for the info. I would also have to install a clutch pedal, perhaps an aftermarket hydraulic if original is unobtanium. Will also of course have to do bodyfab to make the shifter work as well. Just for the bell housing, tranny, clutch disc, and new T-case, how much do you think that might run, and are there any outlets to find these for sale?

If you read through my Polar Bear thread there is quite a bit of info there on NV4500 swaps. As far as cost, that is a moving target depending how detailed you want to go with a swap like that. You might expect to pay $500 to $1500 for the NV4500 itself, $300 for a durable but soft-easy to drive clutch like a DF024909 12” Centerforce dual friction, $350 for the 712576 Advance Adapter bellhousing that will accommodate manual or hydraulic clutch engagement (add $40 for the 715535 hydro bracket if desired), anywhere from $50 to $300 for a 32 spline 208 or 241 tcase (or just replace your current input for less), shifter, flywheel, flywheel bolts, and all the little detail things and unforeseen BS pops up that really add up. In the end it would probably cost a couple thousand to do it right, and by doing it right means not using any aftermarket hydraulic junk that can go wrong when your out in the back country. You would be doing yourself a service to find the OEM pedals from an 85-91 square body style truck, K5, or Suburban and use the corresponding master cylinder, hose and slave. It sure makes it nice to walk in to any parts store and buy factory designed parts when your out in the bush with a break down rather than deal with figuring out how to repair some halfass ill fitting aftermarket stuff. I’ve seen some real hack job NV4500 swaps that cost a fortune and some really nice clean swaps that were done small budget. I have under $1000 in my Polar Bear NV4500 swap but it was a manual trans truck to start with so that saved a bundle but cost me a bundle too as I had to replace the carpet due to the shifter hole changing locations. There are tons of write ups around the internet on NV4500 swaps into old square body rigs to pick ideas from.

Here is a guy selling a complete set up for $2k :Wow1: And you would still have to get the proper tail shaft and t-case adapter installed (at least, maybe even more. Larry would know).

http://orangecounty.craigslist.org/pts/4836314393.html

That trans would work, but the bellhousing on it would not be ideal as that one would have the integrated slave/release bearing assembly. The earlier NV4500’s (93-94) are more desirable due to their much lower granny gear while the later ones have much cleaner shift gates and just shift much nicer all around. Both my K10 (2006 trans) and Suburban (1998 trans) have the later NV4500’s with the less than sterling granny gear but they sure shift nice but leave me constantly wishing for a deeper granny gear.

 

[1stDeuce]

If your trans is blowing smoke above 230, you likely have it overfilled... it really shouldn't do that until the temp is 300+. And if it is overfilled, that will generate a lot of heat too! I think you just need to look into the lockup, and as someone else pointed out, ditch the three coolers and go to one big one. If it isn't enough, then time to cash in on that wonderful AAMCO warranty... But smoking at that low a temp means you're pushing fluid out, which an overfilled trans will do. If you are filling it to the "Full" mark when it's warm, try draining some out until it's at the "Add" mark and take it for a drive that way. It's not going to hurt it at all, and hopefully you'll see it stop smoking.

And it sounds like you're downshifting it based on speed, so as you slow... I"m saying force it to rev a little more by downshifting during the climb. Install a tach and you'll be able to see the converter unlock, and when you see that, drag it down a gear so it locks back up.

And finally, for Rot Box, 4th gear is NOT 1:1, it's .7:1, as in overdrive. I think the OP is saying he tows in 3rd though, which is 1:1, so your numbers apply for trailer towing, and seem very good to me.

OP, if you're reading temp coming out of the pan, you're not getting the trans that hot... Try the fluid level thing and see if that helps.
Or put a NV4500 in it.
C

TV cable adjustment is pretty important. We used to reset them, then ratchet them via WOT for a rough setting. Sometimes I adjust them a little from there to raise the line pressure a bit, but on your trans that shouldn't be necessary.

 

[Rot Box]

And finally, for Rot Box, 4th gear is NOT 1:1, it's .7:1, as in overdrive. I think the OP is saying he tows in 3rd though, which is 1:1, so your numbers apply for trailer towing, and seem very good to me.
y.

Yeah I meant to say 3rd gear 1:1. Sorry..

 

[rayra]

Another vote for taking out three coolers and replacing with one large / dense one. All that extra plumbing reduces flow. Every extra turn reduces flow. Three coolers might actually be making your heating problem worse, as odd as that sounds.
And you didn't say how they were plumbed, hopefully in series. If they're in parallel, two might not be doing much at all.

And too, part of plumbing it into the radiator tank is so you'll stop doing what you are doing when the radiator pressure cap lets loose. Put the plumbing back into the radiator loop and plumb the return line out of the radiator to the oil cooler, then on to the trans. Put the cooler somewhere it doesn't share airflow / heat with the radiator.

Part of the issue is these vehicles typically have a 195F thermostat. Great for emissions. Crap for running in hot climes or towing uphill. So you are running 'hot' from the get-go. Not a lot of margin there. Add a grade like Cajon or the Grapevine and you're running 205F+ running empty. Add a 4k pound tow and you just better slow down.

And make sure your electric fans (if any) are working properly at temp.


Speaking of thermostats, anyone ever seen anything about putting in say a 180F thermostat and having the vehicle comp 're-learn' with it? Difference in mileage? emissions? performance?
The missus commutes on L.A. freeways in her Tahoe and damned if the heat doesn't roil out of that thing for an hour after she gets home. And it's 'normal'.

 

[nick325i]

I really think with one large cooler and Always towing in 3rd and not OD that you would be fine. That is unless the rebuild job wasn't great. It's tough even for a good shop to do a good rebuild on a 700r4 for some reason. The only one I've been around that was rebuild that impressed me. it was built by Jet Performance in CA.

In my part of the world it's always been known and communicated down to always pull a trailer in 3rd in a GM.

 

[Sooper Camper]

personally, i've tried the whole lower t-stat thing on many trucks (GM TBI, Ford EEC and carb). I've found it best to just run with the factory spec'd one, as long as you don't have a block or radiator full of sludge, and fresh coolant. warmer engines burn fuel better, especially with the crappy heads that TBI trucks have. If you are over heating, its not the thermostat's fault...

And yes, it's pretty important IMO to maintain the factory radiator cooling circuit for the trans. liquid to liquid heat exchangers are much more efficient than liquid to air (the add on coolers), and you don't want to over cool the oil back down below 150 as you will be outside the operating temps for the fluid. Rayra is correct, plumb it through the rad cooler, then into 1 large external air cooler, then back to the trans. I pulled this off a V10 Super Duty, apparently the 6.0 Diesel Super Dutys have one twice the size:

on that old burb, you should have no problem fitting a huge cooler off a newer HD truck in there somewhere. Also of note is the different style of coolers you will find...that is a "stacked plate" cooler which is generally the most efficient and most desired (look at nearly every OE trans cooler and they are that style), tube and fin coolers (below) are not as efficient but generally have a lower pressure drop and are the preferred method for power steering fluid coolers (low pressure drop prevents pump starvation). for engine oil, I believe it is best to use a liquid to liquid heat exchanger, so the engine oil is roughly consistent in temperature with the coolant.

i'd like to see where these 3 coolers are mounted and plumbed personally...sounds cramped!

 

[barefoot boy]

+1 what Sooper Camper said.

 

[100acrehuphalump]

Boat anchor?:snorkel: