Technical Gearbox Mk2A and mk2B

[deafmazter]

Hi guys,

Is there a difference between those gearboxes? People are saying that the mk2a gearbox has a longer first gear. Does someone have the ratio of the 188a6000 gearbox?

 

[varesecrazy]

Hi,
What engine..?
1242 8 valve..??

 

[deafmazter]

Hi,
What engine..?
1242 8 valve..??

It’s about the punto hgt 1.8 16v. The mk2a has the 183a1000 engine and the pre facelift (mk2B) has the 188a6000 engine.

A friend of mine has a mk2b and his car runs at 50kmh +- 3200 rpm and mine (mk2a) runs at 50kmh +- 2700 rpm. They also say the mk2a gearbox pulls away faster. He would like a mk2a gearbox under his mk2b. So we want to know if anyone has the gearbox ratios. We already have my mk2a gearbox ratios. So we can confirm those differences in rpm’s

 

[HgtBill]

The HGT box has a shorter 1st gear than the Alfa twin spark equivalents (the internals swap straight over, apparently the Alfa boxes were stronger but I couldn't see a difference, you wouldn't visually be able to tell from the outside).

The Alfa Romeo boxes are generally cheaper & easier to find for essentially the same thing (except 1st gear).

Are you both running the same wheels/tyre sizes?

 

[judderbar]

It’s about the punto hgt 1.8 16v. The mk2a has the 183a1000 engine and the pre facelift (mk2B) has the 188a6000 engine.

A friend of mine has a mk2b and his car runs at 50kmh +- 3200 rpm and mine (mk2a) runs at 50kmh +- 2700 rpm. They also say the mk2a gearbox pulls away faster. He would like a mk2a gearbox under his mk2b. So we want to know if anyone has the gearbox ratios. We already have my mk2a gearbox ratios. So we can confirm those differences in rpm’s

The diesel engine produces more power at lower rpm. The gears between petrol and diesel will not be compatible. You have to rev the hell out of a petrol engine to pull away in low gears. Diesel just goes clunk clunk fowards even if engine hardly turns.

 

[deafmazter]

The HGT box has a shorter 1st gear than the Alfa twin spark equivalents (the internals swap straight over, apparently the Alfa boxes were stronger but I couldn't see a difference, you wouldn't visually be able to tell from the outside).

The Alfa Romeo boxes are generally cheaper & easier to find for essentially the same thing (except 1st gear).

Are you both running the same wheels/tyre sizes?

Yes, both sizes are 195/45/r16 and 7 j, so it’s pretty weird tho..

 

[deafmazter]

The diesel engine produces more power at lower rpm. The gears between petrol and diesel will not be compatible. You have to rev the hell out of a petrol engine to pull away in low gears. Diesel just goes clunk clunk fowards even if engine hardly turns.

Yes, but a 1.9 JTD gearbox will fit on a HGT, but that was not my question. The MK2A and MK2B has a difference of 500/700 rpm each gear, so the mk2b gearbox is absolutely different than the mk2a. But I can’t find the ratio’s of the mk2B..

The ratios I found from the different c.510.5 gearboxes are the alfa 147, GT, fiat bravo/bravo and the brachetta..
the c.510.5.17 from the barchetta has the same ratios als the c.510.5 (punto hgt mk2a) but won’t fit because the outer sizes are different. Thats where the .17 is standing for.

 

[HgtBill]

The Barchetta gearbox internals are the same size as a HGT (1.8 Stilo etc) & all of the Alfa Twin Spark gearboxes (the casings are different). The .17 on the Barchetta refers to the different crown to pinion ratio.

The HGT ratios are the same for all models, regardless of age.

1 - 3.909
2 - 2.238
3 - 1.520
4 - 1.156
5 - 0.872

I'd say one of your boxes has different internals from a different model. I've got the internals of a 2.0 Twinspark in mine (an £80 box versus £300-£400 at the time).

Short of stripping it down, you'd never know looking at the outside of it.

 

[deafmazter]

The Barchetta gearbox internals are the same size as a HGT (1.8 Stilo etc) & all of the Alfa Twin Spark gearboxes (the casings are different). The .17 on the Barchetta refers to the different crown to pinion ratio.

The HGT ratios are the same for all models, regardless of age.

1 - 3.909
2 - 2.238
3 - 1.520
4 - 1.156
5 - 0.872

I'd say one of your boxes has different internals from a different model. I've got the internals of a 2.0 Twinspark in mine (an £80 box versus £300-£400 at the time).

Short of stripping it down, you'd never know looking at the outside of it.

So that's how it is, but it's still strange that there is a difference in RPM. Must be something other than the gearbox or a combination of the two. Thanks for thinking along, it's a lot clearer now.

 

[Mike1alike]

So that's how it is, but it's still strange that there is a difference in RPM. Must be something other than the gearbox or a combination of the two. Thanks for thinking along, it's a lot clearer now.

Don't you have turbo on your car? That might be what's making the difference.

 

[deafmazter]

Don't you have turbo on your car? That might be what's making the difference.

No I haven’t..

 

[Mike1alike]

Then... is your friend hitting 50 km/h on a lower gear than you are?

 

[HgtBill]

The power doesn't affect the speed in gear, that's set by the ratios. You'd just hit a certain speed quicker.

 

[Mike1alike]

Yeah, but... For example, on my Punto I can hit 50 km/h in the 3rd gear on about 2200 RPM or in the 2nd gear on 3000+ RPM.

 

[HgtBill]

Their comparing like for like though.

 

[deafmazter]

Then... is your friend hitting 50 km/h on a lower gear than you are?

I did not say anything about a lower gear. Both were in the same gear and both were at the same speed with the same size tyres and rims.

The mk2b had about (3200 rpm) and mine mk2a (2750 rpm)

I do notice that with a new variator the rpm's have dropped even more, I now drive at 2450 rpm instead of 2750 rpm. So it all stays different.