Hard shifting 4 speed

[bill76]

My 76 blazer with 4 speed is hard to shift out of 1st gear to second,I have to get back in the gas and speed up and then it will pull out of 1 and shift to second---and no I not talking about granny gear or L as gm calls it--
I'am thinking the clutch or pressure plate.
I changed the trans lube and its full.I have been waiting to put a fresh 350 in the truck to do the clutch(at my age its easer to pull engine then that huge 4 speed)---Well the fresh engine is here and I'am ready to go.
Are these tranys known to have this problem,I sure don't feel like tearing into the trans.Thanks in advance for any ideas----Bill

 

[scottsdale86]

My 76 blazer with 4 speed is hard to shift out of 1st gear to second,I have to get back in the gas and speed up and then it will pull out of 1 and shift to second---and no I not talking about granny gear or L as gm calls it--
I'am thinking the clutch or pressure plate.
I changed the trans lube and its full.I have been waiting to put a fresh 350 in the truck to do the clutch(at my age its easer to pull engine then that huge 4 speed)---Well the fresh engine is here and I'am ready to go.
Are these tranys known to have this problem,I sure don't feel like tearing into the trans.Thanks in advance for any ideas----Bill

What makes you think clutch? Is it slipping or shuddering badly? I would be more inclined to suspect a 1-2 gear syncro then the clutch if I was having the issues and you described. How many miles on both the trans and clutch?

 

[diesel4me]

I've found it a bit easier to do clutches by removing the crossmember and bolting it to a transmission jack or floor jack with the adapter plate,and then pull the driveshaft,speedo cable and t-case shift linkages ,and slide the whole assembly back far enough to get the bell housing off...

I've also used a engine hoist & chain or a strap to hold the transmission up by putting the boom in the passenger side door (I took the door off to simplify things,but I've seen it done thru the window or with the door propped open too)..but you'll probably have to remove the transfer case or support it with a floor jack...the other method above is easier if your working alone..

I agree its probably a synchro thats causing the hard shifting,if the clutch was dragging it would likely be hard to shift into all the gears...the second to third gear synchro probably gets the most wear out of all of them,and will be the first to show symptoms...
If the clutch has too much free play it could be contributing to the problem...

 

[bill76]

I guese that I was hoping it would be the clutch,In engages fairly good but is a bit funky sometimes disingageing.God only knows how many miles are on this thing and he's not sure.Just want to get everything in order for a smooth engine swap.
Crud I hate to think about lugging that tranny out and it's been 30 years since I took one of them apart,forgot what they look like inside.
Can the synchro assm be replaced from the front of trans or do I have to tear it down to do it?Any short cuts to doing it?
I guese a trip to brake,clutch and gear are in order to price a synchro assm.
I can shift it but I would like to make it easer for my grandson to drive.
Thanks in advance for any help.-----------Bill

 

[diesel4me]

It might be the clutch,if the pressure plate isn't letting the disc release fully,it'll be hard to upshift and downshift...

The trans will have to come right out to be taken apart to put new synchro's in,the mainshaft has to come out...it might not be a job a novice could do,I personally have just replaced the transmissions myself,never tried to "rebuild" one...though its not rocket science,it is something you should at least have experienced guidance on doing...probably cheaper to just swap another "good used" one in its place...

The SM465's never were a fast shifting transmission,if you "rush" it going from 2nd to 3rd,it might balk at going in easily or clash,especially after high miles or some synchro wear...you might try altering your shifting technique,maybe its not as bad as you think...

If the synchro's are worn,adding some Lucas or STP gear treatment to thicken up the lube might help it too,but when I did that,I had trouble in cold weather shifting my SM465...had to drain it out in the winter and put 80W-90 back in it..mine never was a smooth shifter either,I had to baby it into each gear,it used to clash if I tried shifting into third too "speedily" sometimes..

 

[bill76]

Ya ,I looked in the gm shop manual and it looks like a lotta work,I rebuilt manual boxes before but not one of these guys--my back hurts just thinking of lifting it on the bench--I'll see what the clutch looks like when I pull the engine and then figure what my next plan is.
I can live with it if need be and the granson will just have to deal with it.
And your right about it not being a fast shifting trans,I found that out many many years ago with an old ford f250,Just shift em slow but postive.What the heck its a truck,I'll just drive it like one. Thanks Bill