speed vs. RPM
 

Just got a 'new' pearl SVX as a stablemate to my silver one. The new one has 44K and the silver 111k. At 75 mph the new one turns 3200RPM and the old one turns 2750 RPM. Silver tranny replaced at about 90K and pearls tranny "done' just before I purchased. Both 92 LSL's with pearl being a couple hundred numbers earlier than silver. What gives?
I was surprised and pleased that silver drives just as well as pearl. one or the other is for sale. Thanks, steve

2750 @ 75 is about right; I'd guess that the one you just bought has had its transmission swapped for one with different gearing.

dcb

Hi Steve, sounds like a nice purchase.:D

Steve, your old one doing 75 at 2750 sounds about right for the OEM or original US final drive, which is a stratospherically high 3.54:1 final drive ratio.

As all US cars were sold with the same final drive [unless the FWD ones from 94 are lower and I don't think that's the case] then in theory both your cars should turn the same speed for the same rpms.

What it looks like is a previous owner may have altered the final drive in the newer car. A favoured conversion is to lower the final drive to 4.44:1. Although it revs a bit higher and uses more fuel, lots of people like this conversion. If you find that the 44k miles car feels much faster than the old one, probably your new one has had the FD lowered.

Joe

I much prefer the 'original' 3.54. Is the final drive integral to the tranny or is it separate and how difficult to convert back? Thanks, Steve

Good on you Steve,

A man of with his own logical choices. Will there be flack to follow. :confused:

Unfortunately undoing that done, will be expensive. :eek:

That is exactly the RPM/Speed ratio of 4.44's


reverting is a matter of finding a stock front/rear differential and putting it in. Selling the 4.44 setup here should help offset the cost.


-Patrick

maybe tc isn't locking up?

it's tempting to offer to trade my 3.545 for your 4.44s. Did you say that your is FWD, though? Nevermind, back to eBay!

I rechecked the figures in light of Patrick's comment above.

All else being equal [rolling diametres and so on :rolleyes:] the actual figure for 75 mph in a US car should be around 2,600, while I based my calculation above on 2750 which was an incorrect basis.

With that in mind Patrick is correct, likely it is a 4.44 conversion.

Joe:)

Nowhere did he say FWD.

He in fact said both are '92 Lsls, so must be AWD.

:confused: