View Full Version : Series IIA tranny question

11-25-2006, 08:10 PM
Hi all,
I'm looking at either a tranny replace or adding an overdrive to a 1970 IIA. I need to get a top speed around 70mph as it will be daily driven and sometimes on the highway. I would like all input. Thanks

11-25-2006, 09:47 PM
The easiest way is to install an overdrive unit. The Roverdrive unit has the best reviews, but I run an old Fairy in my SIII. 70 mph is about the fastest I would want to go, considering the capability of the suspension and brakes. Another option is to fit a high ratio transfer case, which allows for a better high speed option but does not affect the original transfer case low range gearing. 5 speed transmission options will require chassis alterations, like repositioning crossmembers and custom length driveshafts. The transfer cases on the later transmissions are designed for full time 4 wheel drive and are to be used with CV joints on the front axles, not with U-joints as on the Series axles. The LT-77 is supposed to be an easier conversion into a Series chassis compared to the R-380, but I have not messed around with one yet.

I'm just finishing a 3.9 V8 and R-380 into an SIIA 109, which required both crossmember work and custom driveshafts.


12-08-2006, 09:25 PM
i've a fairy od in my '64 iia 88 and top end is 60, 70 on a good desent

12-09-2006, 09:09 PM
I second that 70 mph with a 2.25 is a bit ambitious and most likely not worth all the upgrades, puttering along @ 55 mph means you usually get there within 5 minutes of the 70 mph crowd specially commuting or in dense traffic. Now hills you will be be slow anyway, so just my 2cts this might be more complicated then just an O/D

12-10-2006, 12:57 AM
Is this with a stock 2.25? How flat is this highway? the LR will be a lot more comfortable at 55-65, as will you.

Matt Nelson