What Low Ratio Diff's Avail For 79 930 4 Spd?

[PAUL RODELO]

All,

I am looking into low ratio diff's for a 79 930 4 Spd.
I understand there was a popular one back in the 80's.
It made the top speed drop from 165 to 145mph or so.
It also made 2nd gear more useful at street corners
I would not mind a ratio low enough to bring the top speed down to 135mph or so.
What do these cost?.
Does anyone have a good one in their garage.

Thanks,

Paul

[gumba]

Andial use to make a 8:39 but is nla. There are a few other companies making them. I bought a new Andial one for $1450 last year and occasionally see used ones around $1000 and up.

[onboost]

I thought the 8:31 was supposed to be real popular back then.

BTW.. Congrats on the Excellence article! Nice write-up and the car looks hot!

Paul

[Fast82930]

I've been running the Andial 8:39 for 5 years now and think they also had an 8:41.

The factory 4-speed at 6500 rpm in 4th gear is good for 189mph if you have the HP. With the 8:39 R&P it drops to 164mph.

[rg500930]

ive also been running the 8:39.i find 1st a little to short.but the rest of the gears i like.

[PAUL RODELO]

I was considering the upgrade.
Boy the car would be really quick

Onboost, thanks for the Congrats!
Ya, it's my 1st Porsche in Excellence.
Imagine..it's in the September issue
and we are in mid July.
Glad you enjoyed the article.

Hope to see everyone at the German Auto Fest.

Paul

[rlh930]

You might consider changing the gear ratios rather than the diff. This runs around $750/gear. I lowered the 1st/2nd/3rd gear ratios around 20% and it made a big difference. I left 4th alone to have a highway cruising gear.