3.266 diff crown and pinion - fit ISF diff or not?
Moderator
Joined: Apr 2017
Posts: 3,069
Likes: 978
From: Indiana
It’ll have traction issues with summer tires. I spent a year drag racing with summer tires and had issues the entire time with the stock gear. It’ll be fine with drag radials. We don’t have launch control and roll out from the line. The gearing will help to make up for that.
I would avoid drag radials until you update all 4 diff. bushings. Stickier tires + luxury car bushings + more gear + well prepped track = wheel hop.
Yes I’m aware of this and all of the gear calculations, mph, and rpm range, I used the same chart. I knew traction was going to be an issue but I don’t think the performance on Friday is a fair indicator when guys with slicks were not hitting their average 60fts. 3 tenths+ off for that matter (did I mention literally everyone left?) .i can hook better on the street than a track that is supposed to be prepped with VHT. This Friday is bracket racing so they should prep the track fairly well. We shall see if the different gear’s juice is worth the squeeze. If it gets me a better time, i think it’s worth the modification, if I have to get a drag radial than idk because it’s an unfair comparison because I never raced with a drag radial. Daily driving on the gs350 diff is not a PITA and completely bearable. I feel little to no difference when daily driving but a good difference in acceleration.
Driver
Joined: Mar 2019
Posts: 107
Likes: 28
From: NC
Yeah I was planning on doing them. When I got the diff out, it was a sad day when I realized I should have done my bushings at the same time
Moderator
Joined: Apr 2017
Posts: 3,069
Likes: 978
From: Indiana
Moderator
Joined: Apr 2017
Posts: 3,069
Likes: 978
From: Indiana
Driver
Joined: Mar 2019
Posts: 107
Likes: 28
From: NC
What are your comparisons of your 60s, 1/4 time and mph? (Street vs DR). Also, mods? I’ve been looking toward r888rs (I’m on 19s) if I can sell these 13 gs350 f sport rims, i want to buy 18s for a dedicated set. There is a very limited selection of DRs at 19.
Moderator
Joined: Apr 2017
Posts: 3,069
Likes: 978
From: Indiana
I run with an average DA of 2200 or so, so my times are slow. I also haven’t had much track time this year with evening classes. I think my car has better times in it. I need to play with tire pressures and go when the weather is better. With gears I feel confident I could hit high 11s at my current DA. I have only gotten in 6 runs on my current set up. I had probably 60 on my last setup... so driver mod is pending.
I don’t correct my times. I just post what I run in humid Indiana.
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Driver
Joined: Mar 2019
Posts: 107
Likes: 28
From: NC
Off my memory, my best 60 ft with street tires was 1.9. Most of the time it was 2-2.1. Now every run it’s 1.9. I dropped from averaging 12.7-12.8 (best of 12.65) down to an average of 12.30 (best 12.28). My trap is now 119. It used to be 117 at best I think, but would vary down to 113. It really just depended on how I could hook. My car was wildly inconsistent on street tires. I also added intake, tune, and lighter wheels though.
I run with an average DA of 2200 or so, so my times are slow. I also haven’t had much track time this year with evening classes. I think my car has better times in it. I need to play with tire pressures and go when the weather is better. With gears I feel confident I could hit high 11s at my current DA. I have only gotten in 6 runs on my current set up. I had probably 60 on my last setup... so driver mod is pending.
I don’t correct my times. I just post what I run in humid Indiana.
I run with an average DA of 2200 or so, so my times are slow. I also haven’t had much track time this year with evening classes. I think my car has better times in it. I need to play with tire pressures and go when the weather is better. With gears I feel confident I could hit high 11s at my current DA. I have only gotten in 6 runs on my current set up. I had probably 60 on my last setup... so driver mod is pending.
I don’t correct my times. I just post what I run in humid Indiana.
Moderator
Joined: Apr 2017
Posts: 3,069
Likes: 978
From: Indiana
Does the 17-19 Gs350 have the same pattern and bolt in? I am currently looking for a torsion optioned one. They are not cheap, so I’m hoping to confirm it’ll fit. That’ll save me the time in finding someone to set gears in my current diff.
Driver
Joined: Mar 2019
Posts: 107
Likes: 28
From: NC
I cannot speak on that. I didn’t research those years
A Torsen diff isn't a great choice for drag racing. Supra guys blew them up pretty regularly. You'd be better off buying a clutch type - Cusco or OS Giken - they'll hook much better.
Check post #2 in the linked thread for the ugly pics of the inside.
Check post #2 in the linked thread for the ugly pics of the inside.
Manual transmission vehicle with power beyond capability of even the most modified Isf done turned his spool from a torsen to a torsion.
A Torsen diff isn't a great choice for drag racing. Supra guys blew them up pretty regularly. You'd be better off buying a clutch type - Cusco or OS Giken - they'll hook much better.
Check post #2 in the linked thread for the ugly pics of the inside.
Check post #2 in the linked thread for the ugly pics of the inside.
Last edited by tas02; Jun 5, 2019 at 01:46 PM.
Driver
Joined: Mar 2019
Posts: 107
Likes: 28
From: NC
Hey all, I’m thinking about changing back to the stock diff. With the mods that I have (Vr Tune, HPS elbow, aFe filter, xForce Exhaust) I am dying at the back end of the 1/4 mile. Just by comparing similar ETs. The acceleration is there but kinda just slows down up top. I ran today on 275/35/19 R888Rs, 1/2” above OD and puts my FD at 3.6~. So today, I did 12.49 @ 112.18, 60ft 1.9289. My fastest on stock diff with A/S tires is 12.5297 @ 113.66, 60ft @1.984. Now to compare similar 12.54s. Stock diff: 12.5449@113.88,2.01. GS350 diff: 12.5408@111.89,1.9139. The acceleration differences are at 1/8th mile, stock 8.2218@89.82 gs 8.1599@88.77. Identical DAs for each. KCLV on stock was 22.8 and KCLV today was 20.3. Will KCLV make that much of a difference? Should I try again after getting my KCLV back up? what do y’all think? I remember spinning on the stock diff, the R888Rs will hook it no doubt.
I had a long argument with a long time friend about putting a lower gear in the diff. He said "no real difference with 8 gears." Sad to see your numbers supporting his conclusion.