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3.33 ratio 440T4 transmission needed


OrangeCat
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What vehicle came with a 4T60 in the 3.33 ratio? Not saying it doesn't exist, just that I have not ever heard of one. I know the ratio can be changed by swapping sprockets around for the chain drive and that multiple possibilities exist. 

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All '88-90 Reattas came with 2.97 final drive ratio.......there were no options.

In 1991 Buick made the Reatta final drive ratio 3.33 and it was the electronic version of the 4T60 transmission.

I know very little about automatic transmissions except they sometime seem fragile and expensive to repair.

Because it is a FWD transmission it operates differently than a rear drive cars differential which contains the final ratio.

In the 4T60 there is a chain drive that connects the engine output to the transmission guts....it appears this can be changed to

alter the final ratio.....which makes me scratch my head because it is actually changing the engine output speed before going into the guts,

not after which to me "final drive" would be the actual definition.

There is a differential assembly and that too can be changed to alter the final ratio but it is not clear how many parts make up the gear set

for the actual final drive.   A good transmission repair person could probably explain and make up a transmission with the 3.33 final ratio you desire.

Unfortunately,  I do not know of another GM car that used that final ratio.... Buick Riviera had a 3.06 that may have been used on the T-type

By changing tire size you can get about the same overall ration difference.... going from 215 x 65r15 to 215 x 50 r 15 is just under a 10% change in overall ratio

 

Edited by Barney Eaton (see edit history)
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13 hours ago, Barney Eaton said:

All '88-90 Reattas came with 2.97 final drive ratio.......there were no options.

In 1991 Buick made the Reatta final drive ratio 3.33 and it was the electronic version of the 4T60 transmission.

I know very little about automatic transmissions except they sometime seem fragile and expensive to repair.

Because it is a FWD transmission it operates differently than a rear drive cars differential which contains the final ratio.

In the 4T60 there is a chain drive that connects the engine output to the transmission guts....it appears this can be changed to

alter the final ratio.....which makes me scratch my head because it is actually changing the engine output speed before going into the guts,

not after which to me "final drive" would be the actual definition.

There is a differential assembly and that too can be changed to alter the final ratio but it is not clear how many parts make up the gear set

for the actual final drive.   A good transmission repair person could probably explain and make up a transmission with the 3.33 final ratio you desire.

Unfortunately,  I do not know of another GM car that used that final ratio.... Buick Riviera had a 3.06 that may have been used on the T-type

By changing tire size you can get about the same overall ration difference.... going from 215 x 65r15 to 215 x 50 r 15 is just under a 10% change in overall ratio

 

Well I actually have a '90 Bonneville SSE, so I think a Reatta transmission would probably preserve the "sport" feeling. I have the GX3 axle which is 3.33 final drive ratio.

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14 hours ago, 2seater said:

What vehicle came with a 4T60 in the 3.33 ratio? Not saying it doesn't exist, just that I have not ever heard of one. I know the ratio can be changed by swapping sprockets around for the chain drive and that multiple possibilities exist. 

Mine is a Bonneville SSE.

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30 minutes ago, OrangeCat said:

Mine is a Bonneville SSE.

Interesting. I guess it would make sense the Bonnie would have such a thing if anything did. I wonder if the LeSabre T-Type from 89 may have as well? I have seen on the Fiero forums those people do a lot of engine and transaxle switching, focused on performance for the most part. Our friend Ryan from GM Tuners may have some ideas.

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Looking at a 1989 Buick Product manual,  the Riviera had a MX0 code transmission as well as the Reatta, LeSabre, Electra, & Regal.

The Regal had a 2.8 V6 so I don't know if it is actually the same transmission but the gear ratios are the same as the transmission on the other.

The Regal had a 3.33 final ratio

LeSabre had 2.84 standard.... Ttype = 2.97

Electra had 2.97 no options

Riviera had 2.84 standard,  2.97 optional with Grand Touring option

I do not know if there is one source that gives this information for all year Buicks and other GM cars with the 3800 engine.

Orange cat has said above that his Bonneville SSE (what about an SSEI?) has 3.33 

Did Cadillace use the 4T60 transmission behind it front drive cars?   Probably no performance rations there unless on Touring models.

Pontiac GP might be another place to look.

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