Anyone use B&M Shift Improver??

nhproxr · December 6, 2004

Just wondering if anyone has used a B&M shift improver on their trucks. It has 3 settings, stock, firm, and firmer shifts. I towed a couple of sleds through the mountains of NH yesterday in my 16' enclosed trailer (only about 2600 lbs. total) with my '98 Yukon and after about an hour on the road I could faintly smell trans fluid. Truck ran fine and fluid is still red with no burnt smell, but it makes me very nervous. I kept the tranny in 3rd all the time except when rolling down the backside of big hills I'd throw it in OD.

Being a SUV it shifts extremely softly, so I was hoping that running this shift improver would firm up shifts and cool things down a little.

My truck does have HD tranny with deep pan and filter and trailering package with tranny cooler, so I'm surprised I even had a problem at all. Guess its those d**n 3.42 gears killing me!!!

Shaners · December 6, 2004

I put one on my '97 F250 and it worked great. It's very easy to install...

Rookie · December 6, 2004

I also have an 98 Yukon with The towing package, but the D**M 342. I put it on and it seems to work good. The only down fall is you cant not change the settings on the fly. You need to turn the motor off, set it to where you want then restart. Not sure why but i talked to bill out at BMM and he stated that was how it worked on the 4l60e Trans. It tricks the computer to hold higher line pressure. This then firms up the shifts and holds the gears longer. Summit sells them for 39.95 Part number BMM-70380. It takes about 15 minutes total to install.

nhproxr · December 6, 2004

rookie, so it made a nice improvement with towing? What do you tow and what does it weigh? You'd think the HD trans would be heavy duty enough to handle a few thosand pounds.

In addition to the 3.42 gears, I noticed your running 265s on your truck. I too stepped up to the 265s and I'm sure it doesn't help considering it raises the gearing even more.

Rookie · December 6, 2004

I did'nt notice that much with the tire. I was fearing putting them on from all the talk on this forum. I tow a 19 Foot Four Winns open Bow. I'm not sure of exact weight but if i remember correctly boat and trailer are 52 or 5,500 pounds. I dont have a tranny gauge hooked up so i could'tn tell you if it dropped the tranny temp. I did notice the engine is running on an average about 10 degrees cooler on the same strech of road. on;ly thing i can think is the tranny cooler and the rad work together. I also get a kick out of driving it around with it on. The shifts are much firmer it make it fun. For the price you also cant beat it. I would get it.