MR2 Owners Club

gavsdavs wrote: ↑03/08/21 21:42 Also, play with this.

https://mr2.phpwerx.net/turbocalc/gearratios.php

Had a go with it, I don't know how 2 calculators can be slightly different when the input values are the same
Your calculator provided the attached image results. A few mph less on each gear than the one I previously linked

Fuppylodders wrote: ↑03/08/21 22:30

gavsdavs wrote: ↑03/08/21 21:37 FWIW, stock MR2 rear tyre sizes are 225/50/15
or more often seen these days: 245/40/17

I run a 245/40/17 and it's within 1% of GPS speed (but then i no longer use an E153 so it may be irrelevant)

You are running 225/45/17, i'm not sure if that's a smaller rolling circumference to a 225/50/15

24.97 is the tire diameter of 225/45/17
23.86 is the diameter of 225/50/15
So the 15 sliiiiiightly smaller.

Also, I do believe the e153 5th gear can be swapped out easily. I've been told by a few people already it can (I'm only talking from what I've been told, I don't want to say you're wrong, but what I've been told and shown in a video does lead me to believe it can be done)
Video of an e154f (I know, not an E153 but essentially the same, just with a transfer case on it)
5:11 to 6:55

Nothing else needs to be removed. At that point, 5th gear can be swapped out with another. I'd previously had inklings there may be an e53 5th gear in mine, as it matches the ratio to speed to the assumed rev limit of 6250 almost perfectly.

Ask yourself how likely it is that you have a gearbox with a modified 5th that you've been given silently (a change is usually expressed as an upgrade, isn't it)

I've always been told (by paul W and Gouky) that the way you extend ratios in an E153 is to change the final drive (and oil pump gear and ring gear), as there are 3 different variants, where the turbo mr2 variant uses the shortest ratios (and the E51 from a manual camry uses the tallest).

I had an E153 with a 4.125 set and a 3.933 set. Andy Ayres sought out the 3.6 set and uses that.

I'm not categorically stating you can't change the 5th on an E153, I've just never heard of it. I'm also saying that it's pretty common to have people change 5ths in an S54 (the N/A gearbox) and it's often done in v6 converted MR2s.

Up to you what you believe/can work out.

If you really want taller ratios, change your final drive, use taller tyres.

gavsdavs wrote: ↑04/08/21 12:08

Ask yourself how likely it is that you have a gearbox with a modified 5th that you've been given silently (a change is usually expressed as an upgrade, isn't it)

I've always been told (by paul W and Gouky) that the way you extend ratios in an E153 is to change the final drive (and oil pump gear and ring gear), as there are 3 different variants, where the turbo mr2 variant uses the shortest ratios (and the E51 from a manual camry uses the tallest).

I had an E153 with a 4.125 set and a 3.933 set. Andy Ayres sought out the 3.6 set and uses that.

I'm not categorically stating you can't change the 5th on an E153, I've just never heard of it. I'm also saying that it's pretty common to have people change 5ths in an S54 (the N/A gearbox) and it's often done in v6 converted MR2s.

Up to you what you believe/can work out.

If you really want taller ratios, change your final drive, use taller tyres.

I'd say its entirely a possibility, given I know nothing of its history, given how limiting it is on my top speed when there are no issues between 1-4 and whatever its revving to, is the same in all gears.
I know full well I can change the FD, being in the uk, makes it difficult to get hold of a different final drive.

For me and my uses, its certainly not an upgrade, its like having two 4th gears. No one wants two 4th gears unless they want it on a track where they're less likely to hit 150 but know they can make it to 130 kinda thing. I don't know, I have no idea why. I just know it feels wrong.

I'd sooo love to get my hands on a 3.9 set, but, given how sought after they are, and my lack of contacts (and luck) it won't be happening anytime soon.
It also still doesn't answer my original question posed at the start as its that info that'd be the final nail in the coffin for my thoughts/educated assumptions

There's really only one way to be sure, take it out and count the teeth. Given you don't know what rpm your doing, any other method is basically guesswork.

I picked up a 3.9FD set from Gouky, they were still available in the US (this was 2013, mind you)

Alternatively scour the scrap yards for manual camrys. Not sure where Andy got his from.

If your 4th and 5th are almost identical I don't know what's happened.

You do kind of need to know your RPM, everything is speculation

jimi wrote: ↑04/08/21 14:48 There's really only one way to be sure, take it out and count the teeth. Given you don't know what rpm your doing, any other method is basically guesswork.

I understand the ratios... But how do I determine how many teeth its meant to have?
I'll certainly be doing that anyway, will be easy enough once the tyranny is out to pop the end case off.

Why not use an OBD reader for the RPM. Did Paul wire up the obd port ?

gavsdavs wrote: ↑04/08/21 15:52 I picked up a 3.9FD set from Gouky, they were still available in the US (this was 2013, mind you)

Alternatively scour the scrap yards for manual camrys. Not sure where Andy got his from.

If your 4th and 5th are almost identical I don't know what's happened.

You do kind of need to know your RPM, everything is speculation

Camry's weren't available in the uk at that point, I got more chance of finding unicorn poo at a scrappy

Not quite everything, but I get your point

gavsdavs wrote: ↑04/08/21 17:43 Why not use an OBD reader for the RPM. Did Paul wire up the obd port ?

Not entirely sure tbh. I'm not even sure where it was if I'm honest because celica ones never worked-fault codes were always done by bridging a wire across two connector points in thr engine bay.
I'll need to look into it. I think I may know where it could be, it does only have 4 wires connected to it though (even though there's space for about 3 times as many)

Here's the plug-it was under the steering wheel.
Does anyone recognise it? Can it be the obd2 with only 4 wires?
https://flic.kr/p/2mfto5n
2021-08-05_07-56-00

OK, so, doing a little research, it is it, and it reads canbus (the grey is canbus high and one below that is canbus low-not sure what that means just yet, but I'ma look into it).

yeah obd2 in its basic form is a serial protocol, doesn't need too many wires. Stick a reader on it.

gavsdavs wrote: ↑06/08/21 22:58 yeah obd2 in its basic form is a serial protocol, doesn't need too many wires. Stick a reader on it.

Reader ordered

I bought an ELM327 reader out of China years ago now on Ebay it was as cheap as chips. Software like Torque lite is free on your mobile but I bought a licensed copy of Scan Master for a Windows PC.

https://www.ebay.com/itm/272884217107

Works great with Toyota and Subaru doesn't work on BMW but nothing ends up working on a BMW never worked on such junk.