3.15 to 3.36 review - Riviera (with a wild twist at the end)

[85 Riviera]

First, this is not a turbo car. This is a stardard rivi that has been modified. It is powered by a 403 cubic inch oldsmobile with a 214/224 camshaft, 2400 stall, edelbrock intake, ported everything, modified trans, and a bunch of other junk but anyway who cares...

Since alot of people are always asking if the 3.15 to 3.36 ratio swap is worth it...

onward with my review (with a wild twist at the end)...

I installed the 3.36, took me 4 hours total in the florida heat to get this thing in. The 3.36 is not that much shorter (ratio wise) than the 3.15 but it is indeed shorter. With the 3.15 I would cruise at 67.5 MPH at 2000 RPM's, with the 3.36 I am at 2200 RPM's at 67.5 MPH. With the 3.15 I would go into 3rd at 70 MPH under WOT, with the 3.36 I see 3rd at 64 MPH (shifting at 5200 RPM's)

Traction.... I have modified the front end to hook as well as possible and the car has 235/55/16 tires (stock wheels would never hook)!. The 3.36 is harder to hook than the 3.15, even though I can get it to hook through 1st gear, it is on a fine line and any bump on the road can cause the wheels to break loose. I guess that means the 3.36 was a improvement, as the 3.15 was more tractable.

The nice thing about the 3.36 is when you upshift, with the 3.36 is closes in the gaps between the gears, so going to the next gear doesnt feel like it is having to reach too far or pull from too low of RPM's.

I would say its faster, maybe not by much. Although the 3.15 was pretty solid and fast, I think the 3.36 just has an extra edge. I wouldnt be afraid to use the 3.15 if I built so much power that traction became a big problem, but for now the 3.36 is working for me. Nice thing about the 3.36 is I can build the engine up even more without worring about loosing torque (from larger cams, intake and so on).

Now heres the funny of the day...

I was testing my car out on a very wide city street late last night to see how it would pull out of a red light. I looked beside me and this guy in a little honda was looking like he wanted to test me (people see a big blue Riviera as a easy target). Although I didnt care about him as I knew he wasnt even going to be able to hang, I was really only testing and didnt care about the car next to me. Light turned green and I feed into it as fast as traction would allow. The Honda beside me tried but was not even a issue. as I was going through my gears WOT I looked in the rear view and seen the lights of a F body just 3 car lenths behind me. I was like "ok maybe he's into this like its a race".
I backed off the throttle at 70 MPH (no need in going to fast on a city street). The minute I let off, the F body behind me turned on its LIGHTS!. That car was a state trooper (great). He was behind me at the light and followed me all the way through my little wide open blast.
He pulled me over, walked up, he said "what were you doing back there".
I responded "I just installed a new final drive and was just testing to see how it would pull out of the hole".
He said "well I could take you".
So I said "you think so?"
He said "Im in a camero"
I said "yeah thier pretty fast"
Then he said " No really though, I had to go wide open just to barely keep up with you, but you wasnt gonna leave me"
Then he said "I dont feel like writing a ticket today, I'd say your final drive is doing fine so drive safely from here out"
I said " Yes Sir!"

Thats such a wild story that my wife thinks I made it up, but it sure enough it did happen. I know that trooper enjoyed the race LoL!

 

[turbofish38]

I did a lot of experimenting with my final drive too. I think the only reason Buick went back to a 3.15 in 85 on the turbo cars was because of traction. Maybe I just drive with a heavy foot but the 3.36 cars do spin the tires earlier and longer than the 3.15. Also I went to a shorter tire on the front to up the ratio a little more. The last tire I went to the strip with was a 225/50 on a 4WD S-10 15X7 rally wheel which is 24" in diameter. If I figure it out right that is almost a 3.70 final drive. When I get done rebuilding the motor in my current project T-Type I plan on trying some of those slicks made for the imports. I get a little tire hop when the street tires dont hook. I've made a few of those 5-8 pound launches and when the tires hook these cars fly. A little torque steer but easily manageable.

My favorite kill stories envolve those little imports but the ones I really like to get into with are those guys in the RWD Impala SS's.

 

[85 Riviera]

Yeah them 4WD rims do fit. The rims I bought are aftermarket American racing rims that where originally installed on a 4WD blazer. They measure 16x7.5 with a 5.75 backspacing. They fit perfectly, no rub at all anywere!

Using a gear calc if you originally used 205 70 15 tires then your 225 50 15 would be like having a 3.745 ratio.

If you originally had 205 75 15 then you rratio would be like having 3.816

If you dont mind me asking, what have you run on the 1/4 mile. And also, how did the gearing changes effect your MPH? I been told better gearing would lower your MPH but give you a better time. What has been your lcuk with that?

 

[Turbo Riviera]

Love those F-bodies...

When I drove my Riviera on the street daily, I spanked an LT1 convertible f-body one day. He had quite a hottie of a girlfriend/wife with him and you should have seen the look on her face when I looked over at them at the next stop light... She was so embarrassed!

 

[TRiv]

Reposting reply after the 18th hacking, anyway,glad to hear that diff is working good, too bad for the trooper trouble, but it happens at least he let you go! While were talking Rivieras here, just letting you guys know that there is a front brake upgrade we can do to our cars using the later 98-03 Camaro/firebird front dual piston calipers and 12 inch rotors.

I just recieved a kit sold on ebay to Typhoon/Cyclone and 4x4 S10 owners (83 up) to convert steering knuckles ( same as E body) to use the Camaro/Firebird front brake set up. I want to be 100% sure this works, everything looks to be ok, there is some trimming of the steering knuckles required ( cutting off caliper mounts) and grinding after which the parts in kit bolt right up. The kit does not include the factory brake parts (calipers, pads, rotors) but has adaptor brackets, proper grade bolts, ss flexible lines, and misc. including detailed intructions with pics. looks to be well thought out, the only other thing required will be the use of 16" diameter or larger wheels. I was wondering if the 93-99 Pontiac Bonneville aluminum styled wheels (16x7) that look very similar to the GNX style wheel would fit our cars? I am thinking so as those Bonnevilles are fwd.

I bought this kit because my mid engine (turbo Buick) project uses Riviera suspension pieces front and rear, and needs the bigger brakes for the cars application, however the brake upgrade could be a good thing for the T Type Riviera or other hi-perf Rivieras. Again, I would like to be 100% sure to suggest, will have to get busy and do the upgrade, if anyone is interested, I'll post the results and auction, one of those ebay "store" sales.