Rice n Beans Garage Posted June 23, 2017 Report Share Posted June 23, 2017 Getting back into Ratsuns, had a few 620's, looking at 521's now, which 5 speed fits, and will it make it a little more bearable on the freeway ? Thanks in Advance, Scott 1 Quote Link to comment
flatcat19 Posted June 23, 2017 Report Share Posted June 23, 2017 Have you even attempted to search? 1 Quote Link to comment
Rice n Beans Garage Posted June 23, 2017 Author Report Share Posted June 23, 2017 I will, just trying to get some quick info 1 Quote Link to comment
datzenmike Posted June 23, 2017 Report Share Posted June 23, 2017 Fit to the L series engine.... FS5W63A, FS5W71B, FS5C71A or B, FS5R90A Fit the vehicle? Closest is the FS5W63A but you will need to change/modify (see ]2eDeYe for ready made ones) the trans mount and press a 40mm engine core plug into the end of your bolt on driveshaft spline. You will also have to get used to the retarded reverse above first gear shift pattern... R 2 4 1 3 5 Five speed use... The L16 will never be driven fast enough to harm it. Red line is well over 8K and a stock engine lacks carb, head and cam to seriously get there. You might like a little quiet and/or a very small increase in mileage if you do drive long distances out on the highway. If around town a 5 speed never gets used. A 5 speed will not make the truck any faster. The FS5W63A has a 0.854 or 14.6% over drive fifth gear. If your tire is, say, 26" diameter and you are going 60 MPH the RPMs would be a hair under 3,400. With this five speed it would be about 2930 RPMs. That's a drop of 470 RPMs. How much mileage increase will you get? Who knows. Keep in mind that the engine is very small so tooo much overdrive will drop the RPMs to a point where it isn't making enough power to push through the air or climb hills. Differential use... You can get the same thing by replacing the rear differential and lowering from 4.375 to a 3.90 ratio. This would give you a 12% reduction in RPM in every gear. A 3.70 ratio would reduce them by 18%. If you don't haul any loads and do a lot of highway driving this would be much cheaper and easier to do. (I was bored and waiting for my coffee to 'mature' in the French Press. One of the few great contributions to civilization by the French) 2 Quote Link to comment
Tucson620 Posted June 23, 2017 Report Share Posted June 23, 2017 Pity bump: I found these threads helpful - not all the pics are still there. I put a FS5W71B from a Z into mine, L20B at same time. http://community.ratsun.net/topic/38871-521-transmission-swap/ http://community.ratsun.net/topic/35311-jons-521-l20b-5-speeed/ http://community.ratsun.net/topic/14696-hessianbens-521-l16-to-l20b-swapperoooo/ Bit of a project - you got your transmission fitment issues with shifter/length, tranny mount, and driveshaft/carrier. Big time help on highways though. 1 Quote Link to comment
flatcat19 Posted June 23, 2017 Report Share Posted June 23, 2017 I will, just trying to get spoon fed. 1 Quote Link to comment
Tucson620 Posted June 23, 2017 Report Share Posted June 23, 2017 I will, just trying to get spoon fed. Alright then. I'm gonna change 2 characters in each link. Make it a challenge. :) 1 Quote Link to comment
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