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> Jensen Healey & Jensen GT Tech > Engine & Transmission > Differential- 4 speed & 5 speed difference |
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> Jensen Healey & Jensen GT Tech > Engine & Transmission > Differential- 4 speed & 5 speed difference |
| Moderated by: Greg Fletcher |
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| Differential- 4 speed & 5 speed difference | Rate Topic |
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| Posted: 12-27-2005 02:24 pm |
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1st Post |
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nvandal Member
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Can anyone tell me how the rear end gear ratios were different between the four and five speed? Also, how would I know which I have. I pulled a five speed Getrag tranny and rear axle off a 75. I'd like to be certain which differential I have Thanks muchly, norm Vandal
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| Posted: 12-27-2005 06:38 pm |
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2nd Post |
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Judson Manning Member 
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Norm, The 5-sp cars have a 3.45:1 ratio while the 4sp cars have a 3.73:1 ratio, both look VERY similar. Confusing matters is the early 4sp cars had different brakes (Girling/Lockheed) and a different sized input flange. The 'extra' 5sp gear is really a lower first gear to give the impression of an overdrive at top is still 1:1. The Supra 1st gear is lower than the 4sp trans, but almost identical in 2nd, 3rd & 4th. 3.45:1 is a bit tall for a high revving 2.0 car. The hot ticket is a 3.73 RE in a car with either 5sp transmission.
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| Posted: 12-28-2005 02:04 am |
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3rd Post |
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Jensen Healey Super Moderator 
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The "hot ticket" for driving on the freeway with either stock transmission is the 3.45:1. Can you imagine driving across the country at 4200 rpm with a 1:1 diff and only making 70 mph? Forget it, I'll fly.
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| Posted: 12-28-2005 02:25 pm |
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4th Post |
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Judson Manning Member
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Exactly... Who in their right mind would want to be in a car that doesn't meet 1975 roll-over requirements, has no side-impact protection, no crush zones, no air-bags, and could easily drive under an 18-wheeler? On top of that who wants to be in a car long distance that has no sound deadening, no lumbar support, no cruise control, a marginal sound system, and no climate control? I guess we're all a bit insane.... 360miles one-way is my record going to Jacksonville, FL loaded up for a race. I have no idea how Aaron Gross drove from Atlanta to NY for Nationals without going insane, but he did it. With the lack of torque supplied by our beloved 907, there is a real limit to how 'tall' we can make the gears. I'm afraid our LBC will never be much of a highway crusier. Perhaps we should all have a JH and an Interceptor?
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| Posted: 04-11-2009 08:20 pm |
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5th Post |
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Gary Martin JH 15371 Member
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I have a question about the early and late 4 speed differentials. I have two 74 Mark 2 cars. Both have the larger driveline flange on the differential. My 2nd car is John Kimborough's damaged car, and the rear differential housing is bent. I want to replace the diff so it will roll and drive. I know where there are several 73 mark 1 parts cars in the area but I'm sure they have the smaller diff flange. Can the flange be interchanged between the two? I know about the crush pinion sleeve, and that doing this swap might, or wouuld require the gear mesh to be re-adjusted. Is this possible for a reasonably talented home mechanic? Or should I just look for a later 4 speed diff? I know I could just swap the drive line as well, but I would rather keep the later one with the larger U joints. Anyone know where I might find one in Oregon, Washington area? Gary Last edited on 04-11-2009 08:23 pm by Gary Martin JH 15371 |
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| Posted: 04-12-2009 06:03 am |
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6th Post |
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Jensen Healey Super Moderator
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I have a spare diff from a '74 4 speed. I think the flange diameter is 3 3/4" but I'll check tomorrow. Come and get it, free. I have no idea of the condition but it has been living outside for at least 4 years. Kurt
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| Posted: 05-09-2009 05:39 pm |
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7th Post |
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Jim DeClerck Member 
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Just read these posts and I guess I'd be classified "insane". In '82, when I bought 14482, I was transferred from the San Francisco area to Chicago. I drove her all the way, passing through Rocky Mountain N. P. in June. It snowed up there over 12,000 ft. Then the sun came out and it was fine. No mechanical issues except a failing U-joint on the prop shaft in Minnesota. Just drove on through and had it repaired in Chicago. A few years later I drove her on to Rochester, NY for another transfer. Had the body worked on, new paint, seats, radio, carpet, water pump, etc. The kids learned stick shift in her. Then had her shipped back to CA in '91 for the final transfer. Still own her, occasionally drive her and enjoy her.
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| Posted: 07-07-2009 05:59 pm |
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8th Post |
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sjensen24 Member
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I found 15092 in Fresno, CA about five years ago and drove it home to Minneapolis. It was actually a fairly comfy ride. Alternator problems on the way had me driving through North Dakota without headlights and laying up overnight to charge batteries.
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| Posted: 06-24-2010 03:26 pm |
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9th Post |
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thesnyder Member
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San Diego to Portland in August. Car turned over 100,000 miles on that trip, no trouble anywhere. Put the top down in Ashland and drove the last 5 hours enjoying the zen of the Jensen-Healey at a comfortable 70 mph. Stock four speed 74 vin 15390. Must of been a good week at the plant.
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