Re: [AMC-list] 151 4cyl trans to 258-6 interchange question

[Ken Ames <ameskg@xxxxxxxxx>]

I'd have to check the references but I THINK this is the only year that the 4
and 6 SR4s had different ratios. Later ones all had the 4:1 1st. (?)
With a 2something:1 differential I prefer the 4:1.

Ken 


Quoting Frank Swygert <farna@xxxxxxx>:

> Both the 151 and the 258 used the SR4 transmission in 1980 according to the
> TSM. The gear ratios, however, are different. 
> 
> Gear  4cyl.  6cyl.
> 1st   4.07   3.50
> 2nd   2.57   2.21
> 3rd   1.66   1.43
> 4th   1.00   1.00
> R     3.95   3.39
> 
> This shouldn't be a problem, but the torque rating of the transmission is
> usually dependent on the physical diameter of the gear, with a larger
> diameter gear (and higher ratio) capable of taking more torque. 
> 
> I would go ahead with it, but not "pound" on the car. When driven hard, the
> SR-4 is just adequate behind a six. I have a worn out one from a 79 Spirit
> that had 90K on it. 3-4 synchro is gone, had to hold it in 4th when driving,
> and most of the bearings were noisy also. I'm sure the thing was driven
> pretty hard by some kid just before I bought it for parts, but it WAS running
> and driving when I bought... just barely! If you're going to drive more
> normally you should be fine, but do a lot of burn-outs and other hard driving
> and it won't last long. 
> 
> A Mustang T-5 will bolt up to the SR-4 bell housing. You'll have to do a
> little research to find out which model (they have different input shaft
> lengths), but that's not hard. Got to www.theamcforum.com and search for "T-5
> swap" and I think you'll find all the info you need. That would be the best
> bet, but can wait until the SR-4 gives problems. 
> 
> As far as I know the input shaft on the four and six cylinder AMC SR-4 are
> the same. You will want to get a six cylinder clutch -- it's stronger than
> the four cylinder version. The four cylinder uses a hydraulic clutch, the six
> the old style linkage in 1980. You can use the hydraulic setup on the six
> though. You might need to get a different slave cylinder or make a bracket
> for the existing one. The clutch arm will need to be changed too. 
> 
> I'm assuming you have a four cylinder car you're wanting to put the six in or
> have found a four cylinder four speed parts car. If the later, you need the
> clutch pedal as well as the master cylinder to use the hydraulic clutch, and
> I definitely recommend going that route over the mechanical linkage, but
> either will work fine. The four cylinder bell housing WILL NOT bolt to the
> six, you must have a six cylinder bell!
> 
> -------------
> Date: Wed, 24 Feb 2010 11:08:33 -0600
> From: "Eddie Stakes" <eddiestakes@xxxxxxxxxxxxxxxxxxxx>
> 
> Claire below is wondering whether a 4sped trannie behind is 151 4cyl will
> stand up to a 258-6. I personally think it would those are indestructible
> little trannies, I believe a Chevy 350 will bolt up to it also. Regardless,
> if anyone here wishes to comment or advise, please feel free to and thanks in
> advance to all who might, be sure to copy your reply to Claire down below
> also who would appreciate it. 
> Eddie Stakes
> 713.464.8825
> eddiestakes@xxxxxxxxxxxxxxxxxxxx
> www.planethoustonamx.com
> 
> 
> 
> From: Clair Maughan  heymaun@xxxxxxxxxxxxx   
> 
>       Hello,  Thanks for the visit about the 77 AMX Hornet drivers door and
> front fender.  Here's my e-mail address.  Could you also check on the 4
> speed, if the AMX is heavier duty than the one behind the 4 cyl.  
> 
> -- 
> Frank Swygert
> Publisher, "American Motors Cars" 
> Magazine (AMC)
> For all AMC enthusiasts
> http://farna.home.att.net/AMC.html
> (free download available!)
> 
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> 


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