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3:88 transmission? ???

FM Former Member
Sorry, to ask a dumb question, but I went thru the topics and didn't find any info on the 3:88 transmission.

I noticed this gearing is offered as a performance upgrade by some builders. What sort of performance does it provide? Does it provide a closer ratio gearing like in the 83-84 Vw Gti's? Is it mostly for quick 0-60 performance, and is really buzzy at freeway speeds?

I just bought a wide body speedster with a leaking rear seal so I'm going to be dropping the engine soon and thought I might kill two birds with one stone. The engine according to the previous owner puts out about 130hp. The current tires are 225/15/50 on the back and 205/15/50 on the front.

Any info would be great.
Thanks.
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FM Former Member
Sorry, to ask a dumb question, but I went thru the topics and didn't find any info on the 3:88 transmission.

I noticed this gearing is offered as a performance upgrade by some builders. What sort of performance does it provide? Does it provide a closer ratio gearing like in the 83-84 Vw Gti's? Is it mostly for quick 0-60 performance, and is really buzzy at freeway speeds?

I just bought a wide body speedster with a leaking rear seal so I'm going to be dropping the engine soon and thought I might kill two birds with one stone. The engine according to the previous owner puts out about 130hp. The current tires are 225/15/50 on the back and 205/15/50 on the front.

Any info would be great.
Thanks.
HossHoss
Paul,
The 3.88 ring and pinion combination actually is a higher (numerically lower) final drive ratio which is often installed to keep the RPM's down at highway speed. Due to the relatively good power to weight ratio of most of these cars, it gives a good combination of acceleration and cruising speed. Some of the guys even use 3.44 r&p's.
FM Former Member
Paul: You may already have a 3:88 ring and pinion. They came stock in some transmissions. What rpm are you turning at 60 mph? With those small tires if it is under 4k you probable have a 3:88.

The way to confirm it is to jack one rear wheel off the ground and see how many revolutions of the engine for one revolution of the wheel. You need to be reasonably accurate. I think second gear was only offered in one ratio (mines a 2.06) so that
FM Former Member
I live in Massachusetts. My car gets very little highway use. Most of my driving is on winding hill roads and around town. I would prefer the stock 4.12 gearing for quick shifts and low speed thrill seeking.

The 3.88 is definitely the way to go for highway driving. 3rd gear can run to 50 mph comfortably.
FM Former Member
I have a nifty little Excell spread sheet with all the formulas embedded. You enter your tire size, trans gear ratios and final axle ratio and it calculates the overall gearing and MPH for any RPM you want. You can even go through the gears and see where your road speed is a each upshift. By comparing proposed changes to your current tires or gearing, you can easily see if you have more or less overall gear reduction.
Don't know how to attach it to this email, but send me a private inquiry at deklipfe@bechtel.com and I will forward.

FM Former Member
I'm currently considering a change in ratios and noted on cbperformance.com web site, on the right side of the home page under the "extras" title, there is a gear ratio calculator that allows you to plot the gear numbers, tire height etc. Until we pull the transaxle I can only guess on ratios based on 4th gear/mph/rpm but based on a .88 fourth gear and 4:12 r&p plus tire dimension, I can get a reasonably close idea of what I would like and that calculator really lets you run the numbers.
Rick
FM Former Member
Rick: If you are looking for a bit of help with your transmission Bruce Tweddle in Burnaby is very particular and quite thorough at a very reasonable price. He has a few used OEM ratios, ZF diff and such so is a good source for parts and knowledge. I have contact info for him somewhere let me know if you want it and I will dig it out. He changed a ratio in mine just before Christmas.
FM Former Member
Bruce, thanks for the info. Actually, I have the same builder that changed 4th gear in Ron O's Roadster working with me on this project. He lives right here in Chilliwack so very convenient plus he drag races a 10 second Beetle which he built and he knows what's up. Thanks for the tip though.
Rick
FM Former Member
Ron, I have a seminar on Sunday and Dave is in Van today. I'm off to LA next Sunday but want get over to your place ASAP.
I'm pulling the transaxle today, planning on a .77 gear for 4th if existing gears are as anticipated with the 4:12 staying in. We'll see when Dave opens it up.
Bruce, what brand gauge and sensor are you using and who supplied it? I've got to build a new exhaust setup to hook up to a new header I got from Henry and this would be the time to plumb one in.
Rick
FM Former Member
Rick: I got my Autometer gauge at Mopac about $80. Heated O2 sensor $45 and bung $3 both from Magnum Engines. For a few bucks more you could probably get it all a Mopac. You will need a fuse for the heater circuit on the O2 sensor and one for the gauge power. You can buy a nonheated O2 sensor ($30) but they are harder to get a good reading from at idle because they cool down and display a richer reading.
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