Just to mess up your numbers Harlan,
Later 1500 Midgets had a 3.75 rear axle. (helped them meet the Fed's
emission and MPG regs)
The 4.22 rear axle ratio was used on the earliest Midgets (Mk 1's) with
948 and early 1098 engines. It was later replaced with the 3.90 ratio (if
memory serves, at the same time as the introduction of semi elliptic
springs). This diff was the std. until about 1976 (77?) when the 3.75 was
installed for the above reasons.
The three "factory" third members are virtually identical except for the
ring and pinion, and for all practical purposes are interchangable.
Rick Morrison (who just had to get his $.02 worth in)
72 MGBGT
74 Midget
On Mon, 8 Jun 1998 17:21:24 -0500 "Harlan Jillson"
<hjillson@argolink.net> writes:
>Hi all,
> This discussion of midget top speed has been going on for a couple
>of
>days now, so I thought I'd throw in my $0.02 worth.
>
> The clarify ( or muddy) the waters a little, I looked up the rear
>axle
>ratio
>for the midget and found numbers like 3.90x1 and 4.22x1 depending on
>year, motor, etc. If you assume a tire size of 165HR70x13 (I don't
>know
>midget tire sizes, so I took a guess for 13 inch rims), and calculate
>the
>circumference of the tire, you get about 69.412 inches or 5.7843 feet.
>Take 1000 rpm x 60 = 60000 revs per hour / 3.9 = 15384.6 revs at the
>axle (3.90 gears) x 5.7843 = 88989.2 feet/hr /5280 = 16.85 mile per
>hour
>per 1000 rpm engine speed ( 15.57 mph / 1krpm for 4.22 gears).
> Therefore with these tires, your midget should do 77.8 mph with the
>4.22
>gears and 84.25 mph with the 3.90 gears. Other tires sizes in this
>range
>should yeild close to the same results. (All these number assume that
>there is no clutch slippage, etc...)
> To boil it all down, if your only getting 50 mph at 4 or 5
>thousand rpm,
>then you've either got 10 inch wheels, or something is bad broke.
>
>My $0.02...
>Harlan
>'70 BGT
>
>-----Original Message-----
>From: Orjan Lovoll (BEST Consulting) <a-orjanl@microsoft.com>
>To: 'robert weeks' <robert@woozy.com>; mgrazian@ltcm.com
><mgrazian@ltcm.com>; mgs@autox.team.net <mgs@autox.team.net>
>Date: Monday, June 08, 1998 1:11 PM
>Subject: RE: Midget Top Speed
>
>
>>Consider yourself lucky.
>>
>>My 67 Midget can barely hit 60 without redlining. At least I think
>it is
>>sixty. I just kinda take an average of the low and high points the
>needle
>>tends to bounce between.
>>Any faster and my spoke wheels give me the speed wobbles anyway. :)
>>
>>Gotta love it.. built in saftey features.
>>
>>
>>
>>-----Original Message-----
>>From: robert weeks [mailto:robert@woozy.com]
>>Sent: Saturday, June 06, 1998 6:16 PM
>>To: mgrazian@ltcm.com; mgs@autox.team.net
>>Subject: Re: Midget Top Speed
>>
>>
>>Hi,
>>
>>That's definately not correct. I had the Midget out this a.m. and
>looked at
>>what speed I was getting at what rpm: I hit 50mph @ 4000rpm in second
>gear,
>>70 @ 4000 in 3rd gear, and the fastest I've had it in 4th gear was
>95mph
>>and I wasn't looking at the tach that time ;-)
>>
>>Sounds like either your spedo is way off or your clutch is slipping
>pretty
>>badly, I'd vote for the slipping clutch.
>>
>>Good luck,
>>
>>Robert Weeks
>>Durham NC
>>1969 Midget
>>1968-70 Abitza
>>http://www.woozy.com/midget/
>>
>>At 9:19 AM -0400 6/5/98, Michael Graziano wrote:
>>>Hey all.
>>>
>>>I drove my 1500 Midget to work today on the highway (for the 1st
>time).
>>It's
>>>top speed was around 50mph @ 4500RPM. Is this correct or is there
>>>something else the matter?
>>>
>>>Mike
>>>
>>>'78 MIdget
>>>'87 300zx
>>
>>
>>
>
>
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