Can someone tell me if I can install a 4 speed top loader from a 3600 into my 3100 replacing my three speed column shift? Thanks
Yes you can but it's not a straight bolt in swap. You will need the humped trans cover from the 4sp truck, the driveshaft, the hanger bearing crossmember, and an open rear end. The 3600 should have a driveshaft that is half torque tube and half open. The open driveshaft transmissions are easy to find, cheap, and does away with the two piece shaft. We recommend this swap to customers a lot. The 4sp with it's deep first gear works really well with a 2.75 ratio rear end and you now start using the "Grandma" first gear that was seldom used before. It's much easier than the S10 swap that is the rage now, is at least a two times stronger transmission, and there is no machining or adaptors. You end up with the same or better highway cruising gear and yet still can use as a truck all at a fraction of the cost and much stronger than the S10. You do have to be at a dead stop to use first gear unless your an old timey truck driver who can put any transmission into any gear at any speed and NOT USE THE CLUTCH.
3 speed to 4 speed Coilover, thanks for the response and information. I'm not sure I understand part of your information. "You say the open drive line transmissions are easy to find" I have all the parts except the humped trans cover from the 3600 but are you saying I need to find an open drive line transmission instead? Or do I modify half of the 3600 drive shaft (torque tube end) to match the open drive line rear end? Without pictures I need information in fluent dumb stuff Take pity and be kind. Thanks again
No, you don't need an open transmission as the 3/4T alread has an open rear end but the rear is geared very deep, a 4.56 IIRC. Using the trans you now have will require an added crosmember to hold the hanger bearing (which your 3600 has) and if your 3100 is a short bed the shaft will have to be shortened. Both the 3sp and 4sp are 1:1 in high gear so you will turn the engine at the same RPM with the 4sp as you did with the 3sp and that's why we go to a much shallower gear and begin using 1st gear to start from a dead stop. It's a much easier job in your case since the 3600 already gives you an open rear end driveshaft set up. Both GM and Ford had rear ends with ratios in the 2.70 range but the Ford pickup has a 5 on 5.5 bolt pattern which gives a big enough axle mounting flange to drill the the Chevy pickup 6 on 5.5 bolt pattern onto. Of course this last tid bit is for long range cruising and if you're using it as a truck hook it up to the 3600 rear end and drive the snot out of it.
4 speed for me coilover thanks for the clarification. Now that I can do open driveline I will look for an upgrade rear end. I assume the same goes for this setup as for the other options and most go for a 3:55 gear ratio. If you have a better recommendation please advise! I really appreciate the help on this one.
The 3/4 ton trans. will bolt into your 1/2 ton with no problems. Except.... The 3/4 ton enclosed U-joint is different from the 1/2 ton U-joint .... as most have different splines. You may be looking at adapting parts from both U-joints or having to fabricate U-joint parts to get everything lined up. The addition of a 4 speed trans. along with the 3:55 ring & pinion conversion will make you think you are driving a different vehicle when compared to the 3 on the tree & 4:11 gearing you now have.
4 Speed for me! Thanks Deadzone, I didn't think about the u-joint issue but I will check it out. I was concerned that the 4 speed input shaft was the same spline or if I had to change the clutch plate out to match so it's nice to know it will bolt right up to the 235. I appreciate your chiming in and the information.
