Thats right I will be documenting the full DIY around getting a Subaru 5 speed to work with my Bostig swap.
So the hardest thing to think about at least for me was the gear ratios to use. Here are some thoughts on how I got there.
You guys may find this helpful in your decision process for which R&P to go with as well as the correct 1-5 gearing. Within the link below is a xls spreadsheet which will allow you to compare 3 different transmission setups against each other. You will need some basic information such as tire info and what your current VW transmission is but from that you can plug away and get rpm and mph data. Column A has rows 16 and 29 which are setup for custom gearing.
What this does not consider is the motors ability to turn the gear. That is why using your current VW gearing is important so you can have a mental baseline on what your engine does today vs the data presented. Some things to keep in mind is what type of motor you have such as being high reving vs more tq based. Just because you put in a tall 5th gear doesn’t mean the motor can do much with it. I focused on the above mentioned as well as creating even spacing of my gears as not to create large gaps such as what I currently have with my 3rd to 4th (.82) VW transmission. There is a 24 mph difference between 3rd & 4th at 3800 rpm which means any rpms I do have in 3rd are quickly lost going to 4th. 4th sure cruises nice on flat land but kills in the mountains or big hills and 3rd gear just cant give the mph the motor could support with correct gearing.
I am going with the following shown on table 2 after considering the above
R&P – 4.44 1st – 3.55 2nd – 2.11 3rd – 1.45 4th – 1.09 5th – 0.87
I am not the original author of the sheet as Shawn Wright was but I enhanced it ALOT to support 3 transmissions compared and expanded the RPM tables to get really detailed.
Hope this helps as it made my decisions much easier on which gearing to go with.
Click here is the link to the spreadsheet for download