I have a naturally aspirated AP1 trackcar with 100k miles on it. My problem at the 2 local tracks was having to downshift into 2nd gear several times a lap when similarly built and driven AP2 cars didnt have to due to the lower overall ratio. I decided to contact Puddymod to get a stage 1.5 rear diff built with a 4.57 gear ratio.

After exchanging multiple emails and discussing the issue together we agreed on the 4.57. This is a tough final drive ratio to find nowadays but I was not in a hurry and Ben did his best to locate one for me. I think he actually pulled it out of his personal car. The gears were cryotreated and micropolished and the diff was built stronger than stock. Im not sure what exactly Ben did to it but its supposed to be able to take much more "abuse". Ben took a core that he already had, built it and shipped it to me in a well packaged box without oil since this is against shipping regulations. He then emailed me detailed break in instructions.

There was an initial break in period and subsequent oil change.

Street impressions:
The 4.57 is known to whine. It does whine, a bit more so than the stock 4.1 but I can only notice it at certain cruising speeds and its mostly muffled by my exhaust sound so no biggie. Cruising with the 4.57 on the freeway is definitely not something you want to do every day unless you are going 60mph. My yellow box is not working so I really dont know what the actual speeds are wrt rpm but you can calculate it. Driving in the city is actually more fun. You can actually take sharp turns in a higher gear due to the increased effective torque. The diff is really smooth so Ben really did a good job setting the backlash and all.

Track impressions:
This would be track dependent but on TWS which is one of my local tracks I do less shifting which is good. Top speed and lap times have not changed but this is hard to say until I get new tires as Im running on heat cycled tires

Overall:
I would highly recommend puddymod for any differential build. He is knowledgeable, helpful and does a wonderful job

 

Running the exact same set up. I love it.

 

Did you find 6th at TWS then?

 

Nope, Im at 9000 rpm in 5th right before I have to brake for 1 and 2. My car is also kinda slow as its running a bit rich due to the iat tables being off on the aem ems. It has to go back for a re-tune after i fix those tables

 

Thank you for posting and giving your honest review I went to a 4.44 as it is nearly the same in performance and OEM quiet. I love the 4.57R it is a great ratio for our car and it is a strong stout gear

Good luck my friend with the car, be safe and enjoy

 

Sweet! I'll find out Friday how mine works out, same setup!