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#1 3 Speed auto
Posted: Sun Jun 02, 2019 5:24 pm
by dooley1414
Hi all.... not asked a question for a while so here goes.... (hope someone can help) no doubt someone can....
I'm not sure if my 3 speed auto. box is going in to top gear?
What would anybody think the revs. should be at 60mph? my rev. counter at 60mph. is about 2500rpm. is this about right?
Des.... Series 3 V12 1971 auto.
#2 Re: 3 Speed auto
Posted: Sun Jun 02, 2019 5:37 pm
by Heuer
Does it have a 3.31 or 3.07 rear axle ratio? If it is a USA car then I presume it is 3.31 which means it would be 2600 rpm at 60mph in top (1.00:1). The V12 is red-lined at 6,000 rpm and that would give a top speed of about 140mph which is about right.
#3 Re: 3 Speed auto
Posted: Sun Jun 02, 2019 5:56 pm
by dooley1414
Hi.... that I'm not sure? Is there a. easy way to tell? Def. Ex. U.S. Car.
#4 Re: 3 Speed auto
Posted: Sun Jun 02, 2019 6:15 pm
by mgcjag
Hi Des.....to tell what ratio diff u have look at the rear cover plate on the diff...at about the 6 o/c position a small lable/metal tag with the ratio stamped on it.....or jack up rear and count how many turns of prop to turn road wheel once......however.....look at the service manual auto gearbox section......drive under light acceleration...1-2nd gear change at about 8-16 mph.....2nd - 3rd about 20-31 mph......watch the rev counter you will see it dip as you change up.......have you tried changing gear manually...Steve
#5 Re: 3 Speed auto
Posted: Sun Jun 02, 2019 6:24 pm
by driver
Hi, that sounds about right ,I have a 3 speed auto.
#6 Re: 3 Speed auto
Posted: Sun Jun 02, 2019 6:46 pm
by dooley1414
mgcjag wrote: ↑Sun Jun 02, 2019 6:15 pm
Hi Des.....to tell what ratio diff u have look at the rear cover plate on the diff...at about the 6 o/c position a small lable/metal tag with the ratio stamped on it.....or jack up rear and count how many turns of prop to turn road wheel once......however.....look at the service manual auto gearbox section......drive under light acceleration...1-2nd gear change at about 8-16 mph.....2nd - 3rd about 20-31 mph......watch the rev counter you will see it dip as you change up.......have you tried changing gear manually...Steve
Hi Steve.... I may be sounding stupid but how would I do it manually? Des.
#7 Re: 3 Speed auto
Posted: Sun Jun 02, 2019 6:53 pm
by mgcjag
How many positions do u have on your gear lever...D for auto gear change or you can select a gear and drive it like a manual car....1 to start...2 to change up to 2nd.....D to change up to 3rd
#8 Re: 3 Speed auto
Posted: Sun Jun 02, 2019 7:40 pm
by dooley1414
mgcjag wrote: ↑Sun Jun 02, 2019 6:53 pm
How many positions do u have on your gear lever...D for auto gear change or you can select a gear and drive it like a manual car....1 to start...2 to change up to 2nd.....D to change up to 3rd
Hi Steve.... sorry yes I have D.... 1 and 2..... I'll try that in 1 and 2 then see if there is a rev. counter and a significant change when I go in to D....
Thanks.
#9 Re: 3 Speed auto
Posted: Mon Jun 03, 2019 10:46 am
by dooley1414
Hi Steve thanks for your help last night I've tried the manual version of changing gear and I've definitely got first second and third and then I stopped again I thought I'd try in the drive position again and it seemed to have woken up doing it manually.... now the automatic (D position) way I've definitely got the first second and third significant changes in the running of the gearbox. Now to re sort out my leak on the gear box sump.... again....
Thanks again Everyone and Steve.
#10 Re: 3 Speed auto
Posted: Mon Jun 03, 2019 10:49 am
by mgcjag
Hi Des...if you had mentioned a gearbox leak i would have sugested check the oil level as this can affect gear change..Steve
#11 Re: 3 Speed auto
Posted: Mon Jun 03, 2019 11:02 am
by dooley1414
Hi Steve.... I did think that but always checked and topped up if necessary? It's only a drip now and again.... I have already changed the sump gasket once but didn't put any sealant on it didn't really think it would be necessary but wish I had now (belt and braces) got to do all over again now. Des.