i think my tranny is gone

blacktahoez71 · June 12, 2004

i have a 1995 2 door tahoe. it has a 3 inch body lift and 33 inch thornbirds with the torsion bars slightly cranked. my tranny has started slipping sometimes it wont even go in gear and its making an unusually loud noise. today it sounded like it was dying when i put it in gear. sometimes if i turn it off it will go in gear but it will barely go it slips in and out of gear. could someone please help me before i go to the shop, thanks.

snoman · June 12, 2004

You most likely did not regear truck when you installed oversized tires and did not install a aux cooler for tranny either. Big Tires + Stock Gears + No Aux Cooling = eventual tranny failure.. Sorry. Those be tires might look "cool" but they are very hard on tranny if you do not regear propely for the load.

blacktahoez71 · June 12, 2004

i bought the truck with the lift and big tires on it. and if i have to rebuild or replace the tranny i will be going with a heavy duty tranny. with an external tranny cooler and it will have all the bells and whistles in case i go to bigger tires or do some towing. will that be all i need or will i need to change the rear end,too?

snoman · June 12, 2004

i bought the truck with the lift and big tires on it. and if i have to rebuild or replace the tranny i will be going with a heavy duty tranny. with an external tranny cooler and it will have all the bells and whistles in case i go to bigger tires or do some towing. will that be all i need or will i need to change the rear end,too?

If you plan to tow, if you install 4.56's with a tranny cooler and rebuild current one, you will not have any further problems. People slap them big tires on them trucks without regearing or even adding extra cooling and then blame "cheap" tranny for failure. A big tranny is not the answer, better gears and a cooler is plus it will make truck a lot zippier too. Also, bear in mind that if you are thinking of upgrading from a 4L60 (or a 700R4) to a 4L80 you will loose low end performance (hole shot) because the 4L60/700R4 has a 3.06 first gear and the 4L80 has only a 2.48.

Frank S · June 12, 2004

You should actually be fine running 33" tires with around 3.73-4.10 gears on that vehicle.I believe that you should have 3.73's as it is but you definitely should run a transmission cooler.

That's basically the first thing I do to any auto tranny vehicle I buy and I've never had a problem with any of them.My last vehicle,the 2000 ZR2 with 33" BFG MT km's,had a cooler on it and 3.73's with no trouble.Yes,I could have used somewhat lower gears but 4.56's would have been way too low for what I needed.

Depending on the amount and type of towing you'll be doing,4.10's would be ideal for your set up.If you only tow sporadically and it's around the size of a jet ski or a small boat/utility trailer,4.56's will be overkill.

snoman · June 12, 2004

You should actually be fine running 33" tires with around 3.73-4.10 gears on that vehicle.I believe that you should have 3.73's as it is but you definitely should run a transmission cooler.

That's basically the first thing I do to any auto tranny vehicle I buy and I've never had a problem with any of them.My last vehicle,the 2000 ZR2 with 33" BFG MT km's,had a cooler on it and 3.73's with no trouble.Yes,I could have used somewhat lower gears but 4.56's would have been way too low for what I needed.

Depending on the amount and type of towing you'll be doing,4.10's would be ideal for your set up.If you only tow sporadically and it's around the size of a jet ski or a small boat/utility trailer,4.56's will be overkill.

3.73 x 33's SUCKS anyway you measure it in a truck! 4.10 is border line and 4.56 is quite doable. Remember we are talking a 5000lb truck with OD and oversize tires, not a 3500lbs car. Even with 4.56's and 33's in OD you are looking at about 2000 rpm at 60mph which is a good combo in a heavy vehical. I remeber when trucks used to come with 4.10 without OD and still get 13 to 15mpg on highway stock. With a 3.73 and 33's you do not have a 4 speed tranny, you have a 3 and one half speed one because you can only use OD when things are just right (basically level ground and no big headwind either) and that is a real waste! and 4.10 would be ideal if you did not tow with 33's not for towing anything other than a few thousand pounds.

Frank S · June 12, 2004

I beg to differ but with 33's and 3.73's in my '00 Z I was running 70 mph at 2200 RPM's and that was with the speedomoeter correction.

I've noticed that most of your posts about pulling have instantly turned into you recommend 4.56 gears and that's absurd.I understand that the truck weighs 5000 pounds but it also came with 265/75/16 tires which are basically the same as a 31x10.50,give or take a little depending on the manufacturer.To think that you have to go to 4.56's from 3.73's on tire upping of 2 sizes is nothing less than laughable.I wouldn't run 4.56's on a fullsized Vortec 350 powered rig unless I was going larger than 35's (possibly on 35's but only because I generally use my vehicles off roading quite often) because it ruins any kind of normal driveability you have for every day useage.

But what the hell do I know?I've only been around this crap since I was 9 years old.

snoman · June 12, 2004

I beg to differ but with 33's and 3.73's in my '00 Z I was running 70 mph at 2200 RPM's and that was with the speedomoeter correction.

I've noticed that most of your posts about pulling have instantly turned into you recommend 4.56 gears and that's absurd.I understand that the truck weighs 5000 pounds but it also came with 265/75/16 tires which are basically the same as a 31x10.50,give or take a little depending on the manufacturer.To think that you have to go to 4.56's from 3.73's on tire upping of 2 sizes is nothing less than laughable.I wouldn't run 4.56's on a fullsized Vortec 350 powered rig unless I was going larger than 35's (possibly on 35's but only because I generally use my vehicles off roading quite often) because it ruins any kind of normal driveability you have for every day useage.

But what the hell do I know?I've only been around this crap since I was 9 years old.

It is absurd only to those that do not understand the true impact of larger tires on heavy trucks and the extra drag they cause. My K3500 with 245 and 4.10 does a like over 2300 at 70 (verified buy a GPS) and it only has a .75 od and the 60 and 700R4 has a .7 OD. I do not gear a truck so that is hunts gears all the time on hills and that OD is worthless with a load but maybe you like your that way because you do not know any better and, you do not know what a real truck is!

Frank S · June 12, 2004

No it is absurd to those who do understand tire sizes and gears.

Let me make this real simple and maybe you can understand:

Using this vehicles stock configuration as an example (3.73's and 265/75's stock)

3.73 gears with 33" tires=3.50 gearing.Very acceptable

4.10 gears with 33" tires=3.85 gearing.Pretty much perfect

4.56 gears with 33" tires=4.28 gears.Way too low for what most people want in an every day driver such as a '97 K5.

The only thing I don't understand here is what you're problem is with seeing that not just everyone will want to be geared that freaking low while seeing no benefits.It takes away from driveability,especially on the freeway.You talk about running 2000 RPM's at 60mph with 33's and 4.56's like it's acceptable for most cases.There is no way in hell that most people who uses their vehicle for a commuter would be happy with that kind of performance.

Maybe it's for you but I know it is definitely not for most people.You need to keep in mind that some may take your advice and do this only to be unhappy later and that's where message board problems start.Just because you'd be happy with that doesn't equate to the best options that others have and like I have demonstrated with factual numbers in this post.

blacktahoez71 · June 12, 2004

so, FRANK S, if my tranny is tore up do i need to get it rebuilt in a heavy duty way and add a cooler and leave the gears alone?

Frank S · June 12, 2004

Definitely have a cooler added.

Take it to a reputeable shop and let them build it.Make sure they have a good guarantee as they ar5e more apt to use good parts and do it right.Ask around and see who people you know suggest and hopefully more than a few ill give the same shop as their answer.

Gears,basically see above.You would be back at about stock by running 4.10's and you would be really low running 4.56's,which is fine if you tow a lot and don't do much highway driving plus off road quite often.If you run the freeways very much I highly doubt you'll like what the 4.56's do for you.You can also add performance bolt ons to regain some power lost by the larger tires.You can stick with your 3.73's as that equates to a 3.50-1 ratio when corrected and your Tahoe should be ok.I know alot of the 4 door 2wds came with 3.42's and did well so you should be ok even though you are 4x4 as long as you don't tow large loads.

It really just depends on what you'd prefer but I'd definitely go with a cooler after the rebuild.The shop you have the build done at would probably cut you a pretty good deal on installing one when they do your transmission so ask them about it.

snoman · June 13, 2004

Definitely have a cooler added.

Take it to a reputeable shop and let them build it.Make sure they have a good guarantee as they ar5e more apt to use good parts and do it right.Ask around and see who people you know suggest and hopefully more than a few ill give the same shop as their answer.

Gears,basically see above.You would be back at about stock by running 4.10's and you would be really low running 4.56's,which is fine if you tow a lot and don't do much highway driving plus off road quite often.If you run the freeways very much I highly doubt you'll like what the 4.56's do for you.You can also add performance bolt ons to regain some power lost by the larger tires.You can stick with your 3.73's as that equates to a 3.50-1 ratio when corrected and your Tahoe should be ok.I know alot of the 4 door 2wds came with 3.42's and did well so you should be ok even though you are 4x4 as long as you don't tow large loads.

It really just depends on what you'd prefer but I'd definitely go with a cooler after the rebuild.The shop you have the build done at would probably cut you a pretty good deal on installing one when they do your transmission so ask them about it.

4.56 is only 10% lower than 4.10 so it is not really low. (4.88 would be getting there and 5.13 would be) I remember running those gear on the street without OD 30 years ago!!! I wish we would have had OD back then because with would have ran 5.13 or deeper back then on the street. You can follow Franks advise and have a truck that is a bit of a slug or take the step and make that baby jump when you want it to and have everyone else wondering why. With OD and 33's it will cruise real sweet too with 4.56's and actuall pull OD on most hills too! BTW 4.56 in drive at 60 will turn about 2800rpm with 33's and put engine in a good speed range to step right out when you jump it and drop out of OD. It should cruise at about 2000 to 2100 at 60 in OD which is just about ideal for trucks mass and drag.

Frank S · June 13, 2004

Well anyway,I've said my piece on this.The numbers don't lie.

Following my opinions,you'll be back to about your performance when you were stock.I am assuming that most people with 33's aren't exactly concerned with how fast their trucks are and if you happen to be then there's no need in worrying about a tranny cooler because you'll be eating u joints and axles left and right if and when you get the vehicle to hook up.

Following snomans advice,you'll have a vehicle that jumps off the line,eats gas like candy and makes some pretty nice rpm noise at 70 mph.

Seem like pretty tough choices to me.

Shotgun · June 13, 2004

When I put 33" tires on my truck with the factory 3.73's it pretty much killed it. Yea it would cruise on the interstate fine,until you came to a nice sized bridge or overpass then it would have to friggen downshift to hold speed on cruise. The 4.56's cured all that and it feels great. It was pretty much a must for me cause I tow a pretty heavy 5th wheel.

You will gain 500 RPM @ 70 MPH by going to 4.56's if you have 3.73's You will gain about 300 RPM by going to 4.10's.

3.73's with 33"tires 2000 RPM @70MPH

4.56''s with 33" tires 2500 RPM @ 70 MPH

snoman · June 13, 2004

Well anyway,I've said my piece on this.The numbers don't lie.

Following my opinions,you'll be back to about your performance when you were stock.I am assuming that most people with 33's aren't exactly concerned with how fast their trucks are and if you happen to be then there's no need in worrying about a tranny cooler because you'll be eating u joints and axles left and right if and when you get the vehicle to hook up.

Following snomans advice,you'll have a vehicle that jumps off the line,eats gas like candy and makes some pretty nice rpm noise at 70 mph.

Seem like pretty tough choices to me.

Pure BS Frank, you do not have a CLUE what you are talking about. I have run 4.56's with OD and it works FINE with good mileage. I will bet you have never had a properly geared "truck" in your life that can really use all four gears on a auto loaded or not. You gear a truck too tall and it will eat more gas than one geared too short too.