4T60E interchangeability

[spoiledred94]

My transmission in my 94 SE is a 4T60 E and has been slipping more more lately. When the car is cold it slips pretty frequently. I have seen some adds for reasonably priced 4T60 E's and am getting the money together now. So what I want to know is are all 4T60E's interchangeable? You know, are 4T60 E's from different years and cars the same? I am aware that there are different FDR's so that would have to be addressed but I would have the correct gears from my old trans to swap in for the new. Also do you know if the 4T60 HD will swap in for my 4T60E?

[00Beast]

The HD will fit, it's just the differential. You will need a new axle, but it all should fit.

[spoiledred94]

The HD will fit, it's just the differential. You will need a new axle, but it all should fit.

Simple sweet and just what the Dr. ordered. Thanks

[sandrock]

The HD will fit, it's just the differential. You will need a new axle, but it all should fit.

Your partially correct. It's been tossed around that the case is also different in that a different metallurgy was used for HD transmissions, but that's not so important anymore. What IS important stems from your statement. True, the major differences lie in the diff and axle, but you can't just swap them UNLESS you stay year specific. Some years had a forward cut pitch, others a reverse cut pitch, in either course or fine cut. You CAN'T mix and match them, and it's impossible to anyways. The only way to change between cuts and years is to change BOTH the diff and the ring gear, and the ONLY way to change the ring gear is to completely dismantle the trans. And if you are that far into it, it's best to rebuild it.

This is why we say unless you know what you are doing, just get the HD trans and save yourself the headache.

Now then, stay away from the 92-93 transmissions. You can use 94-97 transmissions and be electronically compatible. As far as gear ratio is concerned, and you using your current gears in the new trans, stick with only 1994.

[willwren]

The only way to SAFELY use an HD trans in your car is to get both the trans AND both axles from the donor car, and swap diffs. The EASIEST way is to run your stock right axle and diff in the HD, and the HD axle on the left, but that's over-simplifying the problem. As Sandrock has pointed out, there are many other differences and you can end up over your head very quickly. I agree 100% that it's much better to rebuild or use a non-HD trans. Your car doesn't need an HD trans for any reason.

[spoiledred94]

Yeah, I am confused. The reason I want to go with the HD is that I want to eventually put in the L67 motor and continue to enhance the car's performance. The stronger motor would be limited by my E series transmission.

From what I can gather above if I go with the rebuilt HD trans I must replace both of my axles with axles from 1994 HD trans equipped Bonneville and swap the differentials from one trans to the other. That should be no problem: $70 to $80 apiece. The HD trans itself needs to be a 1994 as well. And I would need to swap the differentials ( I would like to go up to a 3.06 FDR). Can I swap the differentials with out tearing apart the trans case?

One thing I can think of that would make this easier is if I had more options regarding the year of the HD transmission.

Thanks. I hope I didn't miss the point.

[willwren]

After you swap diffs, the right side axle won't be able to be HD. It won't mate to the 3.06, as it's spline count is higher, and will only mate with a 3.33 HD diff which gives an overall final drive of 2.97.

The LEFT side will need to be an HD axle as you won't be replacing the reaction drum that axle locks into, and it has to mate to an HD trans. Change the diff FIRST. Do not have it out when you try to install the left side axle, or the reaction drum can tip on you. This assembly was intended to be put together with the transmission in an upright, not horizontal position.

You don't have to butcher the trans to get to the diff, but it's not easy, either:

viewtopic.php?f=12&t=9823&hilit=busted

Remove:
RF wheel
Fender splash guard
Hub
Axle
Strut
Rotate the junk out of the way.
Jack and support the engine/trans
Remove dogbone mount

.....You get the picture, but this is with the trans in the car.

To do it out of the car, just remove the tailshaft housing. Keep in mind you MUST check final drive endplay as dictated in my link above or you'll frag something. If you can't, then have someone do it that knows what they're doing. This is a MUST when swapping diffs of even the same variety.

Were you planning to swap the trans yourself or have it done?

[spoiledred94]

The post about the axles and the differentials is not getting through to me right: Only the left side needs an HD axle, and the differential has to be installed first, right. The right side must be the non HD axle. Does all this vary with the specific FDR of the new transmission? My current FDR is 2.86 (35/35).

I read the first page of that post. It seems very complicated and definetley out of my skill range. I do intend to replace my transmission myself. So I hope that it isn't as complicated as all those performance mods and failures. Some of the specific info on installing the trans and checking final drive end play, etc I assume will show up as I read more. I have the Chilton and FSM's to go a long with this board. I read the chilton and I assume I can do it. I will be reading the FSM's tonight.

The money came in today for this project. I have to get quotes for each part and tool needed. I could sure use some help with that list. I also want to go with an LSD and a shift kit. Where do I look for posts or info on those and about how much are they?

[Jrs3800]

Your current Final drive is 2.84 not 2.86...

You have a 70 Tooth ring gear Regular Pitch, so you have a 2.84 Regular Pitch... You will have to have the Regualr Pitch HD diff.. Keep in ind that some of the 95 Diffs will not interchange with what you have.. None of the 96-97 4T60E's final drives will interchange with yours either.. Unless you completely rebuild the trans and use the correct parts to upgrade to the 96+ components( several parts and too much work.. ) If you want a 3.33 Final drive you'll need to look for the 92-95 cars with F79, your 35/35 DRIVE & DRIVEN will make this a 3.33 overall.. And as well if you are doing that you'll want the 1897 Stall converter as opposed to the 1450 stall you currently have

[spoiledred94]

I think I am getting close to pissing you guys off. This is a big job for me. I've pulled motors but not a trans. Though I am just pulling one and putting another in and swapping the differentials. Which appears to be the biggest problem. I don't know what regular pitch means and I don't know how to find out if the differential in the HD trans is regular pitch. Jay at the wreckers said he had a 2.97 listing for " a gear ratio " for the HD trans I intend to buy (this is the only one I could locate for a reasonable price). Does that number mean FDR or some other ratio? Basically, I am near my funding limit. If the differential swap can be done without buying gears or parts (other than the trans case to extension case seal) then I'll swap the differentials to raise my FDR. If not maybe I should just go with the differential that is already in place on the HD trans if possible. Also, the apparatus for measuring and adjusting end play looks expensive. Can it be rented?


This all looks doable, but again I am still unclear on the differential swap. If I want to skip this can I just leave the original HD differential in place unmodified? (repeat question for clarity) If so how does that effect which axles I need in order to swap the trans'?

Should I see if I can get the VIN for the donor car and then get a printout of the RPO's so I have a better Idea what it's going to take to swap the differentials or what it would take to stay with same diff?

You guys sure know you Bonnevilles. It's soaking in. Just give me time.

[slug]

Chris:

I think you're doing just fine.

You know, I was about to ask in one of the forums if there was interchangeability between 4T60e and 4T65e transmissions. It's hard to find information like that, looked all over the internet (I finally found the answer right in this forum (Sandrock I think) that the answer is a very, very limited yes for close years, and only if you change computer units).

I never dreamed that just a swap from standard to HD trans could be this complicated.

Knowing you a little bit, my advice to you is not to try this.

I very highly respect all the gearheads and admins that have responded (all have helped me out one way or another), but it is clear that even they would have problems doing this. You just can't anticipate all the snags. It's one of those jobs that would require a high level of pain tolerance, a lot of money, and a lot of running around looking for the right parts. You don't even think about doing it unless you're a gearhead.

Maybe I'm reading between the lines too much, but that's how it looks to me.

If in fact it were me, and I really really was set on doing it, I would buy an SSEi parts car (like Bennito's '94 SSEi with the bad transmission), swap out the entire power train right to the hubs, with my fresh HD transmission put in along the way. That way I would have killed two birds with one stone. I could rebuild the L67 at the time or do it later. Depends on how good it's running.

Anyway, this is a little perspective from the pain angle vs the technical angle. Hope it helps!

slug

(edited: I am basically reiterating more or less what willwren said in his first post--either swap a whole bunch of stuff, or (probably better) don't try the HD route in the first place).

[Jrs3800]

Time for some pictures for the better of the 4T60-E knowledge..


#1) This is the 3.33 Diff( this diff is used for the 2.97 Overall ratio and uses a 70 Tooth ring gear )....


#2) This is a 3.29 Diff Reverse Cut Fine pitch( this diff is used for the 2.93 Overall ratio and also uses a 78 tooth ring gear ) This diff will not swap with what you have... Look at this diff and the above Diff and notice the difference and direction in cut on the Pinions..


#3) Looking at the Pic below, if you look at the gear on the right, this is the drive gear, on the left under the steels Overdrive clutch pack is the driven gear...


#4) what you currently have in your 2.84 Trans is a regular cut 2.84 Diff, and that means you have the 35 Tooth Drive and 35 Tooth Driven gears making it a 2.84 Overall ratio..

#5) If you install the 2.97 Transmission Diff what you will actually have is a 3.33 Overall ratio as the 2.97 Trans actually uses the 3.33 diff, but its Overdriven to be a 2.97 Overall.. The Drive gear is 37 Tooth, and the driven is a 33 tooth and that makes it a 2.97 Overall..

#6) 1991-1995 Regular cut pitch should work for you, but if you want the 2.97 Overall you are better off using an SC Trans from a 94-95 unless you want to rip into the trans to replace the drive and driven gears.. Otherwise you'll have to live with a 3.33...

#7) There are axle differences, and at the current I don't have time to research whats what.. There are a couple of years where the 3.06 and the 2.97 SC Trans used the same axles... 94 supposedly was not one of them, and I believe that 2.84 used a different axle.. All in the research here...


Just for note, I was building a 3.29 Trans for my Van... But with the direction I am going I may want to swap out to a 3.05 ratio if I feel that the 3.29 was overkill.. But the problem is the trans I am building was only built for one year and in a few cars... Hard to come by parts for this trans...

What I am going to do is stick with the second unit we built that I set up with a 2.97 Overall( 3.33 diff, 37 Drive and 33 Driven )... I am going to swap the drive and driven gears to 35 drive and 35 driven to attain the 3.33 overall ratio.. I am going to use this trans as it will leave me the possibility to swap to a 3.06 ratio, and finding one from 91-95 Regular cut should not be too hard... If I was to use a 96-97 4T60E Diff I would yet again have to rip the trans apart as the ring gear would have to be changed to accommodate the Regular cut fine pitch Diff..


91-95 Regular Cut, 70 Tooth ring gear

95 Opposite of regular cut fine pitch, 78 tooth ring gear( 95 only in very few cars )

1996-1997 Regular cut fine pitch, 78 tooth ring gear


With both the 3.33 and the 3.06 is you use one of them with the correct axle... You will bang the fuel cut off before you hit the shift...


When you get deep enough into these, you'll end up with this.. Sooner or later my 3.29 will be assembled and ready for use in something else...


Not sure if this helps or not....

[slug]

These pics and this type of information from Don (jr's3800) are invaluable and cannot be found anywhere else on the internet, I know, I've tried. The circle invariably comes back to "pontiacbonnevilleclub.com". This is true also of the rest of the technical information that has been provided in this thread. I'm not just kissing butt , it's true (maybe this thread would be a good basis for a "differential" article in TechInfo).

Anyway, Chris, it occurs to me you have to rate yourself as a mechanic now. Check out Bill Buttermore's TechInfo article on "dropping the trans pan" (under "care and feeding") for a good rating system. Personally, I would rate your project as a solid nine or better. You just have to see what number you give yourself as a "wrench" and go from there.

[spoiledred94]

It helped. You make me think I can do this despite Slug's very reasonable advice. Slug I know that safer is usually better. You have to go with your gut feeling sometimes even if it's not as safe as logic. And I doubt you'd be the type to tell me "I told you so".

Sandrock said earlier that if I stayed year specific (i.e., 1994 original trans and 1994 donor SC trans) I would be fine, including swapping the differentials without internal differential changes. It's clear that I need an HD axle on the left, but Willwren said it would be safest if I used an HD axle on the right also. I think he meant it would be safer, but that to do it I would need to swap out the drum as the original drum and the HD axle cannot be made compatible. Swapping out the drum, I take it, is not something I can do or afford easily.
The 3.33 resulting overall ratio is higher than what I think Willwren said last year when he posted that I wouldn't want to go over 3.06 with my 94 SE (L27). I may have to let that go by me .


This leaves me needing to find out how much it costs to get an endplay measurement and adj. Any suggestions?

I'd like to get the checks cut tomorrow if I can tie down the last of the loose ends.

You are great guys here as most mechanics generally are. I hope this swap will be successfully done by WCBF09.

[Jrs3800]

You really do not want to go over 3.06.... Anything past that on an L27 is overkill for a series I.. Heck the 3.33 may even be overkill for my 3800 III that will be in the van soon.. This is the reason I am leaving my self an open door so that I can swap back to the 3.06 if needed..

You have a 35/35 drive and driven... You can swap to the 3.06 with the HD diff cover.. But because of your 35/35 gear set you options are 2.84, 3.06 or 3.33 .... You have to change the drive and driven to get the 2.97, no way around that at all..

[spoiledred94]

You really do not want to go over 3.06.... Anything past that on an L27 is overkill for a series I.. Heck the 3.33 may even be overkill for my 3800 III that will be in the van soon.. This is the reason I am leaving my self an open door so that I can swap back to the 3.06 if needed..

You have a 35/35 drive and driven... You can swap to the 3.06 with the HD diff cover.. But because of your 35/35 gear set you options are 2.84, 3.06 or 3.33 .... You have to change the drive and driven to get the 2.97, no way around that at all..

To my understanding from above I will end up with a 2.97 FDR as my Drive to Driven is 35/35 now, but with the non HD diff on the HD trans(37/33) I'll get the 2.97. This a little better than my 2.84 and I'd be happy with that for now.

[sandrock]

You're not going to notice that slight of a change, but your computer will. You will have to get your chip flashed for that ratio.

Trust me...I changed my ratios ever so slightly when I did my '93, and it was enough to confuse the computer.

[spoiledred94]

You're not going to notice that slight of a change, but your computer will. You will have to get your chip flashed for that ratio.

Trust me...I changed my ratios ever so slightly when I did my '93, and it was enough to confuse the computer.

I thought I would have to do that from the discussion from last year about this. Can I drive my car after the swap with my stock chip while I get my performance chip upgraded by Ryan? If I remember there was confusion over this. 1: I only get a bad speedo reading or 2: that plus messed up shift points.

[Jrs3800]

If the reluctor wheel on the Diff for the Vehicle Speed Sensor is the same, You should have a 31 Tooth reluctor for the VSS.. If the new diff you have is a 31 tooth your speedo will be right.. But your shift points will be off, as well as TCC Lock and kickdown...

[spoiledred94]

Would just leaving the HD differential on the HD transmission make things easier? Like eliminating the need for an endplay adj ( I would not have the extra $150 cost for the adj and I wouldn't need to rent a truck to take it in for the adj)? Would it also avoid chip/trans incompatibilies? If I went with the HD diff what would my final FDR be (3.33?)

All the parts are purchased and I am ready to except for the hoist. I bought one at Baxters here in PDX, but got my money back because I can't move it with my car.

I need your guy's help with this and thanks for so far.